libATA Developer's Guide Jeff Garzik 2003-2006 Jeff Garzik The contents of this file are subject to the Open Software License version 1.1 that can be found at http://fedoraproject.org/wiki/Licensing:OSL1.1 and is included herein by reference. Alternatively, the contents of this file may be used under the terms of the GNU General Public License version 2 (the "GPL") as distributed in the kernel source COPYING file, in which case the provisions of the GPL are applicable instead of the above. If you wish to allow the use of your version of this file only under the terms of the GPL and not to allow others to use your version of this file under the OSL, indicate your decision by deleting the provisions above and replace them with the notice and other provisions required by the GPL. If you do not delete the provisions above, a recipient may use your version of this file under either the OSL or the GPL. Introduction libATA is a library used inside the Linux kernel to support ATA host controllers and devices. libATA provides an ATA driver API, class transports for ATA and ATAPI devices, and SCSI<->ATA translation for ATA devices according to the T10 SAT specification. This Guide documents the libATA driver API, library functions, library internals, and a couple sample ATA low-level drivers. libata Driver API struct ata_port_operations is defined for every low-level libata hardware driver, and it controls how the low-level driver interfaces with the ATA and SCSI layers. FIS-based drivers will hook into the system with ->qc_prep() and ->qc_issue() high-level hooks. Hardware which behaves in a manner similar to PCI IDE hardware may utilize several generic helpers, defining at a bare minimum the bus I/O addresses of the ATA shadow register blocks. struct ata_port_operations Disable ATA port void (*port_disable) (struct ata_port *); Called from ata_bus_probe() error path, as well as when unregistering from the SCSI module (rmmod, hot unplug). This function should do whatever needs to be done to take the port out of use. In most cases, ata_port_disable() can be used as this hook. Called from ata_bus_probe() on a failed probe. Called from ata_scsi_release(). Post-IDENTIFY device configuration void (*dev_config) (struct ata_port *, struct ata_device *); Called after IDENTIFY [PACKET] DEVICE is issued to each device found. Typically used to apply device-specific fixups prior to issue of SET FEATURES - XFER MODE, and prior to operation. This entry may be specified as NULL in ata_port_operations. Set PIO/DMA mode void (*set_piomode) (struct ata_port *, struct ata_device *); void (*set_dmamode) (struct ata_port *, struct ata_device *); void (*post_set_mode) (struct ata_port *); unsigned int (*mode_filter) (struct ata_port *, struct ata_device *, unsigned int); Hooks called prior to the issue of SET FEATURES - XFER MODE command. The optional ->mode_filter() hook is called when libata has built a mask of the possible modes. This is passed to the ->mode_filter() function which should return a mask of valid modes after filtering those unsuitable due to hardware limits. It is not valid to use this interface to add modes. dev->pio_mode and dev->dma_mode are guaranteed to be valid when ->set_piomode() and when ->set_dmamode() is called. The timings for any other drive sharing the cable will also be valid at this point. That is the library records the decisions for the modes of each drive on a channel before it attempts to set any of them. ->post_set_mode() is called unconditionally, after the SET FEATURES - XFER MODE command completes successfully. ->set_piomode() is always called (if present), but ->set_dma_mode() is only called if DMA is possible. Taskfile read/write void (*sff_tf_load) (struct ata_port *ap, struct ata_taskfile *tf); void (*sff_tf_read) (struct ata_port *ap, struct ata_taskfile *tf); ->tf_load() is called to load the given taskfile into hardware registers / DMA buffers. ->tf_read() is called to read the hardware registers / DMA buffers, to obtain the current set of taskfile register values. Most drivers for taskfile-based hardware (PIO or MMIO) use ata_sff_tf_load() and ata_sff_tf_read() for these hooks. PIO data read/write void (*sff_data_xfer) (struct ata_device *, unsigned char *, unsigned int, int); All bmdma-style drivers must implement this hook. This is the low-level operation that actually copies the data bytes during a PIO data transfer. Typically the driver will choose one of ata_sff_data_xfer_noirq(), ata_sff_data_xfer(), or ata_sff_data_xfer32(). ATA command execute void (*sff_exec_command)(struct ata_port *ap, struct ata_taskfile *tf); causes an ATA command, previously loaded with ->tf_load(), to be initiated in hardware. Most drivers for taskfile-based hardware use ata_sff_exec_command() for this hook. Per-cmd ATAPI DMA capabilities filter int (*check_atapi_dma) (struct ata_queued_cmd *qc); Allow low-level driver to filter ATA PACKET commands, returning a status indicating whether or not it is OK to use DMA for the supplied PACKET command. This hook may be specified as NULL, in which case libata will assume that atapi dma can be supported. Read specific ATA shadow registers u8 (*sff_check_status)(struct ata_port *ap); u8 (*sff_check_altstatus)(struct ata_port *ap); Reads the Status/AltStatus ATA shadow register from hardware. On some hardware, reading the Status register has the side effect of clearing the interrupt condition. Most drivers for taskfile-based hardware use ata_sff_check_status() for this hook. Write specific ATA shadow register void (*sff_set_devctl)(struct ata_port *ap, u8 ctl); Write the device control ATA shadow register to the hardware. Most drivers don't need to define this. Select ATA device on bus void (*sff_dev_select)(struct ata_port *ap, unsigned int device); Issues the low-level hardware command(s) that causes one of N hardware devices to be considered 'selected' (active and available for use) on the ATA bus. This generally has no meaning on FIS-based devices. Most drivers for taskfile-based hardware use ata_sff_dev_select() for this hook. Private tuning method void (*set_mode) (struct ata_port *ap); By default libata performs drive and controller tuning in accordance with the ATA timing rules and also applies blacklists and cable limits. Some controllers need special handling and have custom tuning rules, typically raid controllers that use ATA commands but do not actually do drive timing. This hook should not be used to replace the standard controller tuning logic when a controller has quirks. Replacing the default tuning logic in that case would bypass handling for drive and bridge quirks that may be important to data reliability. If a controller needs to filter the mode selection it should use the mode_filter hook instead. Control PCI IDE BMDMA engine void (*bmdma_setup) (struct ata_queued_cmd *qc); void (*bmdma_start) (struct ata_queued_cmd *qc); void (*bmdma_stop) (struct ata_port *ap); u8 (*bmdma_status) (struct ata_port *ap); When setting up an IDE BMDMA transaction, these hooks arm (->bmdma_setup), fire (->bmdma_start), and halt (->bmdma_stop) the hardware's DMA engine. ->bmdma_status is used to read the standard PCI IDE DMA Status register. These hooks are typically either no-ops, or simply not implemented, in FIS-based drivers. Most legacy IDE drivers use ata_bmdma_setup() for the bmdma_setup() hook. ata_bmdma_setup() will write the pointer to the PRD table to the IDE PRD Table Address register, enable DMA in the DMA Command register, and call exec_command() to begin the transfer. Most legacy IDE drivers use ata_bmdma_start() for the bmdma_start() hook. ata_bmdma_start() will write the ATA_DMA_START flag to the DMA Command register. Many legacy IDE drivers use ata_bmdma_stop() for the bmdma_stop() hook. ata_bmdma_stop() clears the ATA_DMA_START flag in the DMA command register. Many legacy IDE drivers use ata_bmdma_status() as the bmdma_status() hook. High-level taskfile hooks void (*qc_prep) (struct ata_queued_cmd *qc); int (*qc_issue) (struct ata_queued_cmd *qc); Higher-level hooks, these two hooks can potentially supercede several of the above taskfile/DMA engine hooks. ->qc_prep is called after the buffers have been DMA-mapped, and is typically used to populate the hardware's DMA scatter-gather table. Most drivers use the standard ata_qc_prep() helper function, but more advanced drivers roll their own. ->qc_issue is used to make a command active, once the hardware and S/G tables have been prepared. IDE BMDMA drivers use the helper function ata_qc_issue_prot() for taskfile protocol-based dispatch. More advanced drivers implement their own ->qc_issue. ata_qc_issue_prot() calls ->tf_load(), ->bmdma_setup(), and ->bmdma_start() as necessary to initiate a transfer. Exception and probe handling (EH) void (*eng_timeout) (struct ata_port *ap); void (*phy_reset) (struct ata_port *ap); Deprecated. Use ->error_handler() instead. void (*freeze) (struct ata_port *ap); void (*thaw) (struct ata_port *ap); ata_port_freeze() is called when HSM violations or some other condition disrupts normal operation of the port. A frozen port is not allowed to perform any operation until the port is thawed, which usually follows a successful reset. The optional ->freeze() callback can be used for freezing the port hardware-wise (e.g. mask interrupt and stop DMA engine). If a port cannot be frozen hardware-wise, the interrupt handler must ack and clear interrupts unconditionally while the port is frozen. The optional ->thaw() callback is called to perform the opposite of ->freeze(): prepare the port for normal operation once again. Unmask interrupts, start DMA engine, etc. void (*error_handler) (struct ata_port *ap); ->error_handler() is a driver's hook into probe, hotplug, and recovery and other exceptional conditions. The primary responsibility of an implementation is to call ata_do_eh() or ata_bmdma_drive_eh() with a set of EH hooks as arguments: 'prereset' hook (may be NULL) is called during an EH reset, before any other actions are taken. 'postreset' hook (may be NULL) is called after the EH reset is performed. Based on existing conditions, severity of the problem, and hardware capabilities, Either 'softreset' (may be NULL) or 'hardreset' (may be NULL) will be called to perform the low-level EH reset. void (*post_internal_cmd) (struct ata_queued_cmd *qc); Perform any hardware-specific actions necessary to finish processing after executing a probe-time or EH-time command via ata_exec_internal(). Hardware interrupt handling irqreturn_t (*irq_handler)(int, void *, struct pt_regs *); void (*irq_clear) (struct ata_port *); ->irq_handler is the interrupt handling routine registered with the system, by libata. ->irq_clear is called during probe just before the interrupt handler is registered, to be sure hardware is quiet. The second argument, dev_instance, should be cast to a pointer to struct ata_host_set. Most legacy IDE drivers use ata_sff_interrupt() for the irq_handler hook, which scans all ports in the host_set, determines which queued command was active (if any), and calls ata_sff_host_intr(ap,qc). Most legacy IDE drivers use ata_sff_irq_clear() for the irq_clear() hook, which simply clears the interrupt and error flags in the DMA status register. SATA phy read/write int (*scr_read) (struct ata_port *ap, unsigned int sc_reg, u32 *val); int (*scr_write) (struct ata_port *ap, unsigned int sc_reg, u32 val); Read and write standard SATA phy registers. Currently only used if ->phy_reset hook called the sata_phy_reset() helper function. sc_reg is one of SCR_STATUS, SCR_CONTROL, SCR_ERROR, or SCR_ACTIVE. Init and shutdown int (*port_start) (struct ata_port *ap); void (*port_stop) (struct ata_port *ap); void (*host_stop) (struct ata_host_set *host_set); ->port_start() is called just after the data structures for each port are initialized. Typically this is used to alloc per-port DMA buffers / tables / rings, enable DMA engines, and similar tasks. Some drivers also use this entry point as a chance to allocate driver-private memory for ap->private_data. Many drivers use ata_port_start() as this hook or call it from their own port_start() hooks. ata_port_start() allocates space for a legacy IDE PRD table and returns. ->port_stop() is called after ->host_stop(). Its sole function is to release DMA/memory resources, now that they are no longer actively being used. Many drivers also free driver-private data from port at this time. ->host_stop() is called after all ->port_stop() calls have completed. The hook must finalize hardware shutdown, release DMA and other resources, etc. This hook may be specified as NULL, in which case it is not called. Error handling This chapter describes how errors are handled under libata. Readers are advised to read SCSI EH (Documentation/scsi/scsi_eh.txt) and ATA exceptions doc first. Origins of commands In libata, a command is represented with struct ata_queued_cmd or qc. qc's are preallocated during port initialization and repetitively used for command executions. Currently only one qc is allocated per port but yet-to-be-merged NCQ branch allocates one for each tag and maps each qc to NCQ tag 1-to-1. libata commands can originate from two sources - libata itself and SCSI midlayer. libata internal commands are used for initialization and error handling. All normal blk requests and commands for SCSI emulation are passed as SCSI commands through queuecommand callback of SCSI host template. How commands are issued Internal commands First, qc is allocated and initialized using ata_qc_new_init(). Although ata_qc_new_init() doesn't implement any wait or retry mechanism when qc is not available, internal commands are currently issued only during initialization and error recovery, so no other command is active and allocation is guaranteed to succeed. Once allocated qc's taskfile is initialized for the command to be executed. qc currently has two mechanisms to notify completion. One is via qc->complete_fn() callback and the other is completion qc->waiting. qc->complete_fn() callback is the asynchronous path used by normal SCSI translated commands and qc->waiting is the synchronous (issuer sleeps in process context) path used by internal commands. Once initialization is complete, host_set lock is acquired and the qc is issued. SCSI commands All libata drivers use ata_scsi_queuecmd() as hostt->queuecommand callback. scmds can either be simulated or translated. No qc is involved in processing a simulated scmd. The result is computed right away and the scmd is completed. For a translated scmd, ata_qc_new_init() is invoked to allocate a qc and the scmd is translated into the qc. SCSI midlayer's completion notification function pointer is stored into qc->scsidone. qc->complete_fn() callback is used for completion notification. ATA commands use ata_scsi_qc_complete() while ATAPI commands use atapi_qc_complete(). Both functions end up calling qc->scsidone to notify upper layer when the qc is finished. After translation is completed, the qc is issued with ata_qc_issue(). Note that SCSI midlayer invokes hostt->queuecommand while holding host_set lock, so all above occur while holding host_set lock. How commands are processed Depending on which protocol and which controller are used, commands are processed differently. For the purpose of discussion, a controller which uses taskfile interface and all standard callbacks is assumed. Currently 6 ATA command protocols are used. They can be sorted into the following four categories according to how they are processed. ATA NO DATA or DMA ATA_PROT_NODATA and ATA_PROT_DMA fall into this category. These types of commands don't require any software intervention once issued. Device will raise interrupt on completion. ATA PIO ATA_PROT_PIO is in this category. libata currently implements PIO with polling. ATA_NIEN bit is set to turn off interrupt and pio_task on ata_wq performs polling and IO. ATAPI NODATA or DMA ATA_PROT_ATAPI_NODATA and ATA_PROT_ATAPI_DMA are in this category. packet_task is used to poll BSY bit after issuing PACKET command. Once BSY is turned off by the device, packet_task transfers CDB and hands off processing to interrupt handler. ATAPI PIO ATA_PROT_ATAPI is in this category. ATA_NIEN bit is set and, as in ATAPI NODATA or DMA, packet_task submits cdb. However, after submitting cdb, further processing (data transfer) is handed off to pio_task. How commands are completed Once issued, all qc's are either completed with ata_qc_complete() or time out. For commands which are handled by interrupts, ata_host_intr() invokes ata_qc_complete(), and, for PIO tasks, pio_task invokes ata_qc_complete(). In error cases, packet_task may also complete commands. ata_qc_complete() does the following. DMA memory is unmapped. ATA_QCFLAG_ACTIVE is cleared from qc->flags. qc->complete_fn() callback is invoked. If the return value of the callback is not zero. Completion is short circuited and ata_qc_complete() returns. __ata_qc_complete() is called, which does qc->flags is cleared to zero. ap->active_tag and qc->tag are poisoned. qc->waiting is cleared & completed (in that order). qc is deallocated by clearing appropriate bit in ap->qactive. So, it basically notifies upper layer and deallocates qc. One exception is short-circuit path in #3 which is used by atapi_qc_complete(). For all non-ATAPI commands, whether it fails or not, almost the same code path is taken and very little error handling takes place. A qc is completed with success status if it succeeded, with failed status otherwise. However, failed ATAPI commands require more handling as REQUEST SENSE is needed to acquire sense data. If an ATAPI command fails, ata_qc_complete() is invoked with error status, which in turn invokes atapi_qc_complete() via qc->complete_fn() callback. This makes atapi_qc_complete() set scmd->result to SAM_STAT_CHECK_CONDITION, complete the scmd and return 1. As the sense data is empty but scmd->result is CHECK CONDITION, SCSI midlayer will invoke EH for the scmd, and returning 1 makes ata_qc_complete() to return without deallocating the qc. This leads us to ata_scsi_error() with partially completed qc. ata_scsi_error() ata_scsi_error() is the current transportt->eh_strategy_handler() for libata. As discussed above, this will be entered in two cases - timeout and ATAPI error completion. This function calls low level libata driver's eng_timeout() callback, the standard callback for which is ata_eng_timeout(). It checks if a qc is active and calls ata_qc_timeout() on the qc if so. Actual error handling occurs in ata_qc_timeout(). If EH is invoked for timeout, ata_qc_timeout() stops BMDMA and completes the qc. Note that as we're currently in EH, we cannot call scsi_done. As described in SCSI EH doc, a recovered scmd should be either retried with scsi_queue_insert() or finished with scsi_finish_command(). Here, we override qc->scsidone with scsi_finish_command() and calls ata_qc_complete(). If EH is invoked due to a failed ATAPI qc, the qc here is completed but not deallocated. The purpose of this half-completion is to use the qc as place holder to make EH code reach this place. This is a bit hackish, but it works. Once control reaches here, the qc is deallocated by invoking __ata_qc_complete() explicitly. Then, internal qc for REQUEST SENSE is issued. Once sense data is acquired, scmd is finished by directly invoking scsi_finish_command() on the scmd. Note that as we already have completed and deallocated the qc which was associated with the scmd, we don't need to/cannot call ata_qc_complete() again. Problems with the current EH Error representation is too crude. Currently any and all error conditions are represented with ATA STATUS and ERROR registers. Errors which aren't ATA device errors are treated as ATA device errors by setting ATA_ERR bit. Better error descriptor which can properly represent ATA and other errors/exceptions is needed. When handling timeouts, no action is taken to make device forget about the timed out command and ready for new commands. EH handling via ata_scsi_error() is not properly protected from usual command processing. On EH entrance, the device is not in quiescent state. Timed out commands may succeed or fail any time. pio_task and atapi_task may still be running. Too weak error recovery. Devices / controllers causing HSM mismatch errors and other errors quite often require reset to return to known state. Also, advanced error handling is necessary to support features like NCQ and hotplug. ATA errors are directly handled in the interrupt handler and PIO errors in pio_task. This is problematic for advanced error handling for the following reasons. First, advanced error handling often requires context and internal qc execution. Second, even a simple failure (say, CRC error) needs information gathering and could trigger complex error handling (say, resetting & reconfiguring). Having multiple code paths to gather information, enter EH and trigger actions makes life painful. Third, scattered EH code makes implementing low level drivers difficult. Low level drivers override libata callbacks. If EH is scattered over several places, each affected callbacks should perform its part of error handling. This can be error prone and painful. libata Library LINUX Kernel Hackers Manual July 2017 ata_link_next 9 4.1.27 ata_link_next link iteration helper Synopsis struct ata_link * ata_link_next struct ata_link * link struct ata_port * ap enum ata_link_iter_mode mode Arguments link the previous link, NULL to start ap ATA port containing links to iterate mode iteration mode, one of ATA_LITER_* LOCKING Host lock or EH context. RETURNS Pointer to the next link. LINUX Kernel Hackers Manual July 2017 ata_dev_next 9 4.1.27 ata_dev_next device iteration helper Synopsis struct ata_device * ata_dev_next struct ata_device * dev struct ata_link * link enum ata_dev_iter_mode mode Arguments dev the previous device, NULL to start link ATA link containing devices to iterate mode iteration mode, one of ATA_DITER_* LOCKING Host lock or EH context. RETURNS Pointer to the next device. LINUX Kernel Hackers Manual July 2017 atapi_cmd_type 9 4.1.27 atapi_cmd_type Determine ATAPI command type from SCSI opcode Synopsis int atapi_cmd_type u8 opcode Arguments opcode SCSI opcode Description Determine ATAPI command type from opcode. LOCKING None. RETURNS ATAPI_{READ|WRITE|READ_CD|PASS_THRU|MISC} LINUX Kernel Hackers Manual July 2017 ata_tf_to_fis 9 4.1.27 ata_tf_to_fis Convert ATA taskfile to SATA FIS structure Synopsis void ata_tf_to_fis const struct ata_taskfile * tf u8 pmp int is_cmd u8 * fis Arguments tf Taskfile to convert pmp Port multiplier port is_cmd This FIS is for command fis Buffer into which data will output Description Converts a standard ATA taskfile to a Serial ATA FIS structure (Register - Host to Device). LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_tf_from_fis 9 4.1.27 ata_tf_from_fis Convert SATA FIS to ATA taskfile Synopsis void ata_tf_from_fis const u8 * fis struct ata_taskfile * tf Arguments fis Buffer from which data will be input tf Taskfile to output Description Converts a serial ATA FIS structure to a standard ATA taskfile. LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_pack_xfermask 9 4.1.27 ata_pack_xfermask Pack pio, mwdma and udma masks into xfer_mask Synopsis unsigned long ata_pack_xfermask unsigned long pio_mask unsigned long mwdma_mask unsigned long udma_mask Arguments pio_mask pio_mask mwdma_mask mwdma_mask udma_mask udma_mask Description Pack pio_mask, mwdma_mask and udma_mask into a single unsigned int xfer_mask. LOCKING None. RETURNS Packed xfer_mask. LINUX Kernel Hackers Manual July 2017 ata_unpack_xfermask 9 4.1.27 ata_unpack_xfermask Unpack xfer_mask into pio, mwdma and udma masks Synopsis void ata_unpack_xfermask unsigned long xfer_mask unsigned long * pio_mask unsigned long * mwdma_mask unsigned long * udma_mask Arguments xfer_mask xfer_mask to unpack pio_mask resulting pio_mask mwdma_mask resulting mwdma_mask udma_mask resulting udma_mask Description Unpack xfer_mask into pio_mask, mwdma_mask and udma_mask. Any NULL distination masks will be ignored. LINUX Kernel Hackers Manual July 2017 ata_xfer_mask2mode 9 4.1.27 ata_xfer_mask2mode Find matching XFER_* for the given xfer_mask Synopsis u8 ata_xfer_mask2mode unsigned long xfer_mask Arguments xfer_mask xfer_mask of interest Description Return matching XFER_* value for xfer_mask. Only the highest bit of xfer_mask is considered. LOCKING None. RETURNS Matching XFER_* value, 0xff if no match found. LINUX Kernel Hackers Manual July 2017 ata_xfer_mode2mask 9 4.1.27 ata_xfer_mode2mask Find matching xfer_mask for XFER_* Synopsis unsigned long ata_xfer_mode2mask u8 xfer_mode Arguments xfer_mode XFER_* of interest Description Return matching xfer_mask for xfer_mode. LOCKING None. RETURNS Matching xfer_mask, 0 if no match found. LINUX Kernel Hackers Manual July 2017 ata_xfer_mode2shift 9 4.1.27 ata_xfer_mode2shift Find matching xfer_shift for XFER_* Synopsis int ata_xfer_mode2shift unsigned long xfer_mode Arguments xfer_mode XFER_* of interest Description Return matching xfer_shift for xfer_mode. LOCKING None. RETURNS Matching xfer_shift, -1 if no match found. LINUX Kernel Hackers Manual July 2017 ata_mode_string 9 4.1.27 ata_mode_string convert xfer_mask to string Synopsis const char * ata_mode_string unsigned long xfer_mask Arguments xfer_mask mask of bits supported; only highest bit counts. Description Determine string which represents the highest speed (highest bit in modemask). LOCKING None. RETURNS Constant C string representing highest speed listed in mode_mask, or the constant C string <n/a>. LINUX Kernel Hackers Manual July 2017 ata_dev_classify 9 4.1.27 ata_dev_classify determine device type based on ATA-spec signature Synopsis unsigned int ata_dev_classify const struct ata_taskfile * tf Arguments tf ATA taskfile register set for device to be identified Description Determine from taskfile register contents whether a device is ATA or ATAPI, as per Signature and persistence section of ATA/PI spec (volume 1, sect 5.14). LOCKING None. RETURNS Device type, ATA_DEV_ATA, ATA_DEV_ATAPI, ATA_DEV_PMP, ATA_DEV_ZAC, or ATA_DEV_UNKNOWN the event of failure. LINUX Kernel Hackers Manual July 2017 ata_id_string 9 4.1.27 ata_id_string Convert IDENTIFY DEVICE page into string Synopsis void ata_id_string const u16 * id unsigned char * s unsigned int ofs unsigned int len Arguments id IDENTIFY DEVICE results we will examine s string into which data is output ofs offset into identify device page len length of string to return. must be an even number. Description The strings in the IDENTIFY DEVICE page are broken up into 16-bit chunks. Run through the string, and output each 8-bit chunk linearly, regardless of platform. LOCKING caller. LINUX Kernel Hackers Manual July 2017 ata_id_c_string 9 4.1.27 ata_id_c_string Convert IDENTIFY DEVICE page into C string Synopsis void ata_id_c_string const u16 * id unsigned char * s unsigned int ofs unsigned int len Arguments id IDENTIFY DEVICE results we will examine s string into which data is output ofs offset into identify device page len length of string to return. must be an odd number. Description This function is identical to ata_id_string except that it trims trailing spaces and terminates the resulting string with null. len must be actual maximum length (even number) + 1. LOCKING caller. LINUX Kernel Hackers Manual July 2017 ata_id_xfermask 9 4.1.27 ata_id_xfermask Compute xfermask from the given IDENTIFY data Synopsis unsigned long ata_id_xfermask const u16 * id Arguments id IDENTIFY data to compute xfer mask from Description Compute the xfermask for this device. This is not as trivial as it seems if we must consider early devices correctly. FIXME pre IDE drive timing (do we care ?). LOCKING None. RETURNS Computed xfermask LINUX Kernel Hackers Manual July 2017 ata_pio_need_iordy 9 4.1.27 ata_pio_need_iordy check if iordy needed Synopsis unsigned int ata_pio_need_iordy const struct ata_device * adev Arguments adev ATA device Description Check if the current speed of the device requires IORDY. Used by various controllers for chip configuration. LINUX Kernel Hackers Manual July 2017 ata_do_dev_read_id 9 4.1.27 ata_do_dev_read_id default ID read method Synopsis unsigned int ata_do_dev_read_id struct ata_device * dev struct ata_taskfile * tf u16 * id Arguments dev device tf proposed taskfile id data buffer Description Issue the identify taskfile and hand back the buffer containing identify data. For some RAID controllers and for pre ATA devices this function is wrapped or replaced by the driver LINUX Kernel Hackers Manual July 2017 ata_cable_40wire 9 4.1.27 ata_cable_40wire return 40 wire cable type Synopsis int ata_cable_40wire struct ata_port * ap Arguments ap port Description Helper method for drivers which want to hardwire 40 wire cable detection. LINUX Kernel Hackers Manual July 2017 ata_cable_80wire 9 4.1.27 ata_cable_80wire return 80 wire cable type Synopsis int ata_cable_80wire struct ata_port * ap Arguments ap port Description Helper method for drivers which want to hardwire 80 wire cable detection. LINUX Kernel Hackers Manual July 2017 ata_cable_unknown 9 4.1.27 ata_cable_unknown return unknown PATA cable. Synopsis int ata_cable_unknown struct ata_port * ap Arguments ap port Description Helper method for drivers which have no PATA cable detection. LINUX Kernel Hackers Manual July 2017 ata_cable_ignore 9 4.1.27 ata_cable_ignore return ignored PATA cable. Synopsis int ata_cable_ignore struct ata_port * ap Arguments ap port Description Helper method for drivers which don't use cable type to limit transfer mode. LINUX Kernel Hackers Manual July 2017 ata_cable_sata 9 4.1.27 ata_cable_sata return SATA cable type Synopsis int ata_cable_sata struct ata_port * ap Arguments ap port Description Helper method for drivers which have SATA cables LINUX Kernel Hackers Manual July 2017 ata_dev_pair 9 4.1.27 ata_dev_pair return other device on cable Synopsis struct ata_device * ata_dev_pair struct ata_device * adev Arguments adev device Description Obtain the other device on the same cable, or if none is present NULL is returned LINUX Kernel Hackers Manual July 2017 sata_set_spd 9 4.1.27 sata_set_spd set SATA spd according to spd limit Synopsis int sata_set_spd struct ata_link * link Arguments link Link to set SATA spd for Description Set SATA spd of link according to sata_spd_limit. LOCKING Inherited from caller. RETURNS 0 if spd doesn't need to be changed, 1 if spd has been changed. Negative errno if SCR registers are inaccessible. LINUX Kernel Hackers Manual July 2017 ata_timing_cycle2mode 9 4.1.27 ata_timing_cycle2mode find xfer mode for the specified cycle duration Synopsis u8 ata_timing_cycle2mode unsigned int xfer_shift int cycle Arguments xfer_shift ATA_SHIFT_* value for transfer type to examine. cycle cycle duration in ns Description Return matching xfer mode for cycle. The returned mode is of the transfer type specified by xfer_shift. If cycle is too slow for xfer_shift, 0xff is returned. If cycle is faster than the fastest known mode, the fasted mode is returned. LOCKING None. RETURNS Matching xfer_mode, 0xff if no match found. LINUX Kernel Hackers Manual July 2017 ata_do_set_mode 9 4.1.27 ata_do_set_mode Program timings and issue SET FEATURES - XFER Synopsis int ata_do_set_mode struct ata_link * link struct ata_device ** r_failed_dev Arguments link link on which timings will be programmed r_failed_dev out parameter for failed device Description Standard implementation of the function used to tune and set ATA device disk transfer mode (PIO3, UDMA6, etc.). If ata_dev_set_mode fails, pointer to the failing device is returned in r_failed_dev. LOCKING PCI/etc. bus probe sem. RETURNS 0 on success, negative errno otherwise LINUX Kernel Hackers Manual July 2017 ata_wait_after_reset 9 4.1.27 ata_wait_after_reset wait for link to become ready after reset Synopsis int ata_wait_after_reset struct ata_link * link unsigned long deadline int (*check_ready) struct ata_link *link Arguments link link to be waited on deadline deadline jiffies for the operation check_ready callback to check link readiness Description Wait for link to become ready after reset. LOCKING EH context. RETURNS 0 if linke is ready before deadline; otherwise, -errno. LINUX Kernel Hackers Manual July 2017 sata_link_debounce 9 4.1.27 sata_link_debounce debounce SATA phy status Synopsis int sata_link_debounce struct ata_link * link const unsigned long * params unsigned long deadline Arguments link ATA link to debounce SATA phy status for params timing parameters { interval, duratinon, timeout } in msec deadline deadline jiffies for the operation Description Make sure SStatus of link reaches stable state, determined by holding the same value where DET is not 1 for duration polled every interval, before timeout. Timeout constraints the beginning of the stable state. Because DET gets stuck at 1 on some controllers after hot unplugging, this functions waits until timeout then returns 0 if DET is stable at 1. timeout is further limited by deadline. The sooner of the two is used. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno on failure. LINUX Kernel Hackers Manual July 2017 sata_link_resume 9 4.1.27 sata_link_resume resume SATA link Synopsis int sata_link_resume struct ata_link * link const unsigned long * params unsigned long deadline Arguments link ATA link to resume SATA params timing parameters { interval, duratinon, timeout } in msec deadline deadline jiffies for the operation Description Resume SATA phy link and debounce it. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno on failure. LINUX Kernel Hackers Manual July 2017 sata_link_scr_lpm 9 4.1.27 sata_link_scr_lpm manipulate SControl IPM and SPM fields Synopsis int sata_link_scr_lpm struct ata_link * link enum ata_lpm_policy policy bool spm_wakeup Arguments link ATA link to manipulate SControl for policy LPM policy to configure spm_wakeup initiate LPM transition to active state Description Manipulate the IPM field of the SControl register of link according to policy. If policy is ATA_LPM_MAX_POWER and spm_wakeup is true, the SPM field is manipulated to wake up the link. This function also clears PHYRDY_CHG before returning. LOCKING EH context. RETURNS 0 on succes, -errno otherwise. LINUX Kernel Hackers Manual July 2017 ata_std_prereset 9 4.1.27 ata_std_prereset prepare for reset Synopsis int ata_std_prereset struct ata_link * link unsigned long deadline Arguments link ATA link to be reset deadline deadline jiffies for the operation Description link is about to be reset. Initialize it. Failure from prereset makes libata abort whole reset sequence and give up that port, so prereset should be best-effort. It does its best to prepare for reset sequence but if things go wrong, it should just whine, not fail. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 sata_link_hardreset 9 4.1.27 sata_link_hardreset reset link via SATA phy reset Synopsis int sata_link_hardreset struct ata_link * link const unsigned long * timing unsigned long deadline bool * online int (*check_ready) struct ata_link * Arguments link link to reset timing timing parameters { interval, duratinon, timeout } in msec deadline deadline jiffies for the operation online optional out parameter indicating link onlineness check_ready optional callback to check link readiness Description SATA phy-reset link using DET bits of SControl register. After hardreset, link readiness is waited upon using ata_wait_ready if check_ready is specified. LLDs are allowed to not specify check_ready and wait itself after this function returns. Device classification is LLD's responsibility. *online is set to one iff reset succeeded and link is online after reset. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 sata_std_hardreset 9 4.1.27 sata_std_hardreset COMRESET w/o waiting or classification Synopsis int sata_std_hardreset struct ata_link * link unsigned int * class unsigned long deadline Arguments link link to reset class resulting class of attached device deadline deadline jiffies for the operation Description Standard SATA COMRESET w/o waiting or classification. LOCKING Kernel thread context (may sleep) RETURNS 0 if link offline, -EAGAIN if link online, -errno on errors. LINUX Kernel Hackers Manual July 2017 ata_std_postreset 9 4.1.27 ata_std_postreset standard postreset callback Synopsis void ata_std_postreset struct ata_link * link unsigned int * classes Arguments link the target ata_link classes classes of attached devices Description This function is invoked after a successful reset. Note that the device might have been reset more than once using different reset methods before postreset is invoked. LOCKING Kernel thread context (may sleep) LINUX Kernel Hackers Manual July 2017 ata_dev_set_feature 9 4.1.27 ata_dev_set_feature Issue SET FEATURES - SATA FEATURES Synopsis unsigned int ata_dev_set_feature struct ata_device * dev u8 enable u8 feature Arguments dev Device to which command will be sent enable Whether to enable or disable the feature feature The sector count represents the feature to set Description Issue SET FEATURES - SATA FEATURES command to device dev on port ap with sector count LOCKING PCI/etc. bus probe sem. RETURNS 0 on success, AC_ERR_* mask otherwise. LINUX Kernel Hackers Manual July 2017 ata_std_qc_defer 9 4.1.27 ata_std_qc_defer Check whether a qc needs to be deferred Synopsis int ata_std_qc_defer struct ata_queued_cmd * qc Arguments qc ATA command in question Description Non-NCQ commands cannot run with any other command, NCQ or not. As upper layer only knows the queue depth, we are responsible for maintaining exclusion. This function checks whether a new command qc can be issued. LOCKING spin_lock_irqsave(host lock) RETURNS ATA_DEFER_* if deferring is needed, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_sg_init 9 4.1.27 ata_sg_init Associate command with scatter-gather table. Synopsis void ata_sg_init struct ata_queued_cmd * qc struct scatterlist * sg unsigned int n_elem Arguments qc Command to be associated sg Scatter-gather table. n_elem Number of elements in s/g table. Description Initialize the data-related elements of queued_cmd qc to point to a scatter-gather table sg, containing n_elem elements. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_qc_complete 9 4.1.27 ata_qc_complete Complete an active ATA command Synopsis void ata_qc_complete struct ata_queued_cmd * qc Arguments qc Command to complete Description Indicate to the mid and upper layers that an ATA command has completed, with either an ok or not-ok status. Refrain from calling this function multiple times when successfully completing multiple NCQ commands. ata_qc_complete_multiple should be used instead, which will properly update IRQ expect state. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_qc_complete_multiple 9 4.1.27 ata_qc_complete_multiple Complete multiple qcs successfully Synopsis int ata_qc_complete_multiple struct ata_port * ap u32 qc_active Arguments ap port in question qc_active new qc_active mask Description Complete in-flight commands. This functions is meant to be called from low-level driver's interrupt routine to complete requests normally. ap->qc_active and qc_active is compared and commands are completed accordingly. Always use this function when completing multiple NCQ commands from IRQ handlers instead of calling ata_qc_complete multiple times to keep IRQ expect status properly in sync. LOCKING spin_lock_irqsave(host lock) RETURNS Number of completed commands on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 sata_scr_valid 9 4.1.27 sata_scr_valid test whether SCRs are accessible Synopsis int sata_scr_valid struct ata_link * link Arguments link ATA link to test SCR accessibility for Description Test whether SCRs are accessible for link. LOCKING None. RETURNS 1 if SCRs are accessible, 0 otherwise. LINUX Kernel Hackers Manual July 2017 sata_scr_read 9 4.1.27 sata_scr_read read SCR register of the specified port Synopsis int sata_scr_read struct ata_link * link int reg u32 * val Arguments link ATA link to read SCR for reg SCR to read val Place to store read value Description Read SCR register reg of link into *val. This function is guaranteed to succeed if link is ap->link, the cable type of the port is SATA and the port implements ->scr_read. LOCKING None if link is ap->link. Kernel thread context otherwise. RETURNS 0 on success, negative errno on failure. LINUX Kernel Hackers Manual July 2017 sata_scr_write 9 4.1.27 sata_scr_write write SCR register of the specified port Synopsis int sata_scr_write struct ata_link * link int reg u32 val Arguments link ATA link to write SCR for reg SCR to write val value to write Description Write val to SCR register reg of link. This function is guaranteed to succeed if link is ap->link, the cable type of the port is SATA and the port implements ->scr_read. LOCKING None if link is ap->link. Kernel thread context otherwise. RETURNS 0 on success, negative errno on failure. LINUX Kernel Hackers Manual July 2017 sata_scr_write_flush 9 4.1.27 sata_scr_write_flush write SCR register of the specified port and flush Synopsis int sata_scr_write_flush struct ata_link * link int reg u32 val Arguments link ATA link to write SCR for reg SCR to write val value to write Description This function is identical to sata_scr_write except that this function performs flush after writing to the register. LOCKING None if link is ap->link. Kernel thread context otherwise. RETURNS 0 on success, negative errno on failure. LINUX Kernel Hackers Manual July 2017 ata_link_online 9 4.1.27 ata_link_online test whether the given link is online Synopsis bool ata_link_online struct ata_link * link Arguments link ATA link to test Description Test whether link is online. This is identical to ata_phys_link_online when there's no slave link. When there's a slave link, this function should only be called on the master link and will return true if any of M/S links is online. LOCKING None. RETURNS True if the port online status is available and online. LINUX Kernel Hackers Manual July 2017 ata_link_offline 9 4.1.27 ata_link_offline test whether the given link is offline Synopsis bool ata_link_offline struct ata_link * link Arguments link ATA link to test Description Test whether link is offline. This is identical to ata_phys_link_offline when there's no slave link. When there's a slave link, this function should only be called on the master link and will return true if both M/S links are offline. LOCKING None. RETURNS True if the port offline status is available and offline. LINUX Kernel Hackers Manual July 2017 ata_host_suspend 9 4.1.27 ata_host_suspend suspend host Synopsis int ata_host_suspend struct ata_host * host pm_message_t mesg Arguments host host to suspend mesg PM message Description Suspend host. Actual operation is performed by port suspend. LINUX Kernel Hackers Manual July 2017 ata_host_resume 9 4.1.27 ata_host_resume resume host Synopsis void ata_host_resume struct ata_host * host Arguments host host to resume Description Resume host. Actual operation is performed by port resume. LINUX Kernel Hackers Manual July 2017 ata_host_alloc 9 4.1.27 ata_host_alloc allocate and init basic ATA host resources Synopsis struct ata_host * ata_host_alloc struct device * dev int max_ports Arguments dev generic device this host is associated with max_ports maximum number of ATA ports associated with this host Description Allocate and initialize basic ATA host resources. LLD calls this function to allocate a host, initializes it fully and attaches it using ata_host_register. max_ports ports are allocated and host->n_ports is initialized to max_ports. The caller is allowed to decrease host->n_ports before calling ata_host_register. The unused ports will be automatically freed on registration. RETURNS Allocate ATA host on success, NULL on failure. LOCKING Inherited from calling layer (may sleep). LINUX Kernel Hackers Manual July 2017 ata_host_alloc_pinfo 9 4.1.27 ata_host_alloc_pinfo alloc host and init with port_info array Synopsis struct ata_host * ata_host_alloc_pinfo struct device * dev const struct ata_port_info *const * ppi int n_ports Arguments dev generic device this host is associated with ppi array of ATA port_info to initialize host with n_ports number of ATA ports attached to this host Description Allocate ATA host and initialize with info from ppi. If NULL terminated, ppi may contain fewer entries than n_ports. The last entry will be used for the remaining ports. RETURNS Allocate ATA host on success, NULL on failure. LOCKING Inherited from calling layer (may sleep). LINUX Kernel Hackers Manual July 2017 ata_slave_link_init 9 4.1.27 ata_slave_link_init initialize slave link Synopsis int ata_slave_link_init struct ata_port * ap Arguments ap port to initialize slave link for Description Create and initialize slave link for ap. This enables slave link handling on the port. In libata, a port contains links and a link contains devices. There is single host link but if a PMP is attached to it, there can be multiple fan-out links. On SATA, there's usually a single device connected to a link but PATA and SATA controllers emulating TF based interface can have two - master and slave. However, there are a few controllers which don't fit into this abstraction too well - SATA controllers which emulate TF interface with both master and slave devices but also have separate SCR register sets for each device. These controllers need separate links for physical link handling (e.g. onlineness, link speed) but should be treated like a traditional M/S controller for everything else (e.g. command issue, softreset). slave_link is libata's way of handling this class of controllers without impacting core layer too much. For anything other than physical link handling, the default host link is used for both master and slave. For physical link handling, separate ap->slave_link is used. All dirty details are implemented inside libata core layer. From LLD's POV, the only difference is that prereset, hardreset and postreset are called once more for the slave link, so the reset sequence looks like the following. prereset(M) -> prereset(S) -> hardreset(M) -> hardreset(S) -> softreset(M) -> postreset(M) -> postreset(S) Note that softreset is called only for the master. Softreset resets both M/S by definition, so SRST on master should handle both (the standard method will work just fine). LOCKING Should be called before host is registered. RETURNS 0 on success, -errno on failure. LINUX Kernel Hackers Manual July 2017 ata_host_start 9 4.1.27 ata_host_start start and freeze ports of an ATA host Synopsis int ata_host_start struct ata_host * host Arguments host ATA host to start ports for Description Start and then freeze ports of host. Started status is recorded in host->flags, so this function can be called multiple times. Ports are guaranteed to get started only once. If host->ops isn't initialized yet, its set to the first non-dummy port ops. LOCKING Inherited from calling layer (may sleep). RETURNS 0 if all ports are started successfully, -errno otherwise. LINUX Kernel Hackers Manual July 2017 ata_host_init 9 4.1.27 ata_host_init Initialize a host struct for sas (ipr, libsas) Synopsis void ata_host_init struct ata_host * host struct device * dev struct ata_port_operations * ops Arguments host host to initialize dev device host is attached to ops port_ops LINUX Kernel Hackers Manual July 2017 ata_host_register 9 4.1.27 ata_host_register register initialized ATA host Synopsis int ata_host_register struct ata_host * host struct scsi_host_template * sht Arguments host ATA host to register sht template for SCSI host Description Register initialized ATA host. host is allocated using ata_host_alloc and fully initialized by LLD. This function starts ports, registers host with ATA and SCSI layers and probe registered devices. LOCKING Inherited from calling layer (may sleep). RETURNS 0 on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 ata_host_activate 9 4.1.27 ata_host_activate start host, request IRQ and register it Synopsis int ata_host_activate struct ata_host * host int irq irq_handler_t irq_handler unsigned long irq_flags struct scsi_host_template * sht Arguments host target ATA host irq IRQ to request irq_handler irq_handler used when requesting IRQ irq_flags irq_flags used when requesting IRQ sht scsi_host_template to use when registering the host Description After allocating an ATA host and initializing it, most libata LLDs perform three steps to activate the host - start host, request IRQ and register it. This helper takes necessasry arguments and performs the three steps in one go. An invalid IRQ skips the IRQ registration and expects the host to have set polling mode on the port. In this case, irq_handler should be NULL. LOCKING Inherited from calling layer (may sleep). RETURNS 0 on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 ata_host_detach 9 4.1.27 ata_host_detach Detach all ports of an ATA host Synopsis void ata_host_detach struct ata_host * host Arguments host Host to detach Description Detach all ports of host. LOCKING Kernel thread context (may sleep). LINUX Kernel Hackers Manual July 2017 ata_pci_remove_one 9 4.1.27 ata_pci_remove_one PCI layer callback for device removal Synopsis void ata_pci_remove_one struct pci_dev * pdev Arguments pdev PCI device that was removed Description PCI layer indicates to libata via this hook that hot-unplug or module unload event has occurred. Detach all ports. Resource release is handled via devres. LOCKING Inherited from PCI layer (may sleep). LINUX Kernel Hackers Manual July 2017 ata_platform_remove_one 9 4.1.27 ata_platform_remove_one Platform layer callback for device removal Synopsis int ata_platform_remove_one struct platform_device * pdev Arguments pdev Platform device that was removed Description Platform layer indicates to libata via this hook that hot-unplug or module unload event has occurred. Detach all ports. Resource release is handled via devres. LOCKING Inherited from platform layer (may sleep). LINUX Kernel Hackers Manual July 2017 ata_msleep 9 4.1.27 ata_msleep ATA EH owner aware msleep Synopsis void ata_msleep struct ata_port * ap unsigned int msecs Arguments ap ATA port to attribute the sleep to msecs duration to sleep in milliseconds Description Sleeps msecs. If the current task is owner of ap's EH, the ownership is released before going to sleep and reacquired after the sleep is complete. IOW, other ports sharing the ap->host will be allowed to own the EH while this task is sleeping. LOCKING Might sleep. LINUX Kernel Hackers Manual July 2017 ata_wait_register 9 4.1.27 ata_wait_register wait until register value changes Synopsis u32 ata_wait_register struct ata_port * ap void __iomem * reg u32 mask u32 val unsigned long interval unsigned long timeout Arguments ap ATA port to wait register for, can be NULL reg IO-mapped register mask Mask to apply to read register value val Wait condition interval polling interval in milliseconds timeout timeout in milliseconds Description Waiting for some bits of register to change is a common operation for ATA controllers. This function reads 32bit LE IO-mapped register reg and tests for the following condition. (*reg & mask) != val If the condition is met, it returns; otherwise, the process is repeated after interval_msec until timeout. LOCKING Kernel thread context (may sleep) RETURNS The final register value. LINUX Kernel Hackers Manual July 2017 sata_lpm_ignore_phy_events 9 4.1.27 sata_lpm_ignore_phy_events test if PHY event should be ignored Synopsis bool sata_lpm_ignore_phy_events struct ata_link * link Arguments link Link receiving the event Description Test whether the received PHY event has to be ignored or not. RETURNS True if the event has to be ignored. libata Core Internals LINUX Kernel Hackers Manual July 2017 ata_dev_phys_link 9 4.1.27 ata_dev_phys_link find physical link for a device Synopsis struct ata_link * ata_dev_phys_link struct ata_device * dev Arguments dev ATA device to look up physical link for Description Look up physical link which dev is attached to. Note that this is different from dev->link only when dev is on slave link. For all other cases, it's the same as dev->link. LOCKING Don't care. RETURNS Pointer to the found physical link. LINUX Kernel Hackers Manual July 2017 ata_force_cbl 9 4.1.27 ata_force_cbl force cable type according to libata.force Synopsis void ata_force_cbl struct ata_port * ap Arguments ap ATA port of interest Description Force cable type according to libata.force and whine about it. The last entry which has matching port number is used, so it can be specified as part of device force parameters. For example, both a:40c,1.00:udma4 and 1.00:40c,udma4 have the same effect. LOCKING EH context. LINUX Kernel Hackers Manual July 2017 ata_force_link_limits 9 4.1.27 ata_force_link_limits force link limits according to libata.force Synopsis void ata_force_link_limits struct ata_link * link Arguments link ATA link of interest Description Force link flags and SATA spd limit according to libata.force and whine about it. When only the port part is specified (e.g. 1:), the limit applies to all links connected to both the host link and all fan-out ports connected via PMP. If the device part is specified as 0 (e.g. 1.00:), it specifies the first fan-out link not the host link. Device number 15 always points to the host link whether PMP is attached or not. If the controller has slave link, device number 16 points to it. LOCKING EH context. LINUX Kernel Hackers Manual July 2017 ata_force_xfermask 9 4.1.27 ata_force_xfermask force xfermask according to libata.force Synopsis void ata_force_xfermask struct ata_device * dev Arguments dev ATA device of interest Description Force xfer_mask according to libata.force and whine about it. For consistency with link selection, device number 15 selects the first device connected to the host link. LOCKING EH context. LINUX Kernel Hackers Manual July 2017 ata_force_horkage 9 4.1.27 ata_force_horkage force horkage according to libata.force Synopsis void ata_force_horkage struct ata_device * dev Arguments dev ATA device of interest Description Force horkage according to libata.force and whine about it. For consistency with link selection, device number 15 selects the first device connected to the host link. LOCKING EH context. LINUX Kernel Hackers Manual July 2017 ata_rwcmd_protocol 9 4.1.27 ata_rwcmd_protocol set taskfile r/w commands and protocol Synopsis int ata_rwcmd_protocol struct ata_taskfile * tf struct ata_device * dev Arguments tf command to examine and configure dev device tf belongs to Description Examine the device configuration and tf->flags to calculate the proper read/write commands and protocol to use. LOCKING caller. LINUX Kernel Hackers Manual July 2017 ata_tf_read_block 9 4.1.27 ata_tf_read_block Read block address from ATA taskfile Synopsis u64 ata_tf_read_block struct ata_taskfile * tf struct ata_device * dev Arguments tf ATA taskfile of interest dev ATA device tf belongs to LOCKING None. Read block address from tf. This function can handle all three address formats - LBA, LBA48 and CHS. tf->protocol and flags select the address format to use. RETURNS Block address read from tf. LINUX Kernel Hackers Manual July 2017 ata_build_rw_tf 9 4.1.27 ata_build_rw_tf Build ATA taskfile for given read/write request Synopsis int ata_build_rw_tf struct ata_taskfile * tf struct ata_device * dev u64 block u32 n_block unsigned int tf_flags unsigned int tag Arguments tf Target ATA taskfile dev ATA device tf belongs to block Block address n_block Number of blocks tf_flags RW/FUA etc... tag tag LOCKING None. Build ATA taskfile tf for read/write request described by block, n_block, tf_flags and tag on dev. RETURNS 0 on success, -ERANGE if the request is too large for dev, -EINVAL if the request is invalid. LINUX Kernel Hackers Manual July 2017 ata_read_native_max_address 9 4.1.27 ata_read_native_max_address Read native max address Synopsis int ata_read_native_max_address struct ata_device * dev u64 * max_sectors Arguments dev target device max_sectors out parameter for the result native max address Description Perform an LBA48 or LBA28 native size query upon the device in question. RETURNS 0 on success, -EACCES if command is aborted by the drive. -EIO on other errors. LINUX Kernel Hackers Manual July 2017 ata_set_max_sectors 9 4.1.27 ata_set_max_sectors Set max sectors Synopsis int ata_set_max_sectors struct ata_device * dev u64 new_sectors Arguments dev target device new_sectors new max sectors value to set for the device Description Set max sectors of dev to new_sectors. RETURNS 0 on success, -EACCES if command is aborted or denied (due to previous non-volatile SET_MAX) by the drive. -EIO on other errors. LINUX Kernel Hackers Manual July 2017 ata_hpa_resize 9 4.1.27 ata_hpa_resize Resize a device with an HPA set Synopsis int ata_hpa_resize struct ata_device * dev Arguments dev Device to resize Description Read the size of an LBA28 or LBA48 disk with HPA features and resize it if required to the full size of the media. The caller must check the drive has the HPA feature set enabled. RETURNS 0 on success, -errno on failure. LINUX Kernel Hackers Manual July 2017 ata_dump_id 9 4.1.27 ata_dump_id IDENTIFY DEVICE info debugging output Synopsis void ata_dump_id const u16 * id Arguments id IDENTIFY DEVICE page to dump Description Dump selected 16-bit words from the given IDENTIFY DEVICE page. LOCKING caller. LINUX Kernel Hackers Manual July 2017 ata_exec_internal_sg 9 4.1.27 ata_exec_internal_sg execute libata internal command Synopsis unsigned ata_exec_internal_sg struct ata_device * dev struct ata_taskfile * tf const u8 * cdb int dma_dir struct scatterlist * sgl unsigned int n_elem unsigned long timeout Arguments dev Device to which the command is sent tf Taskfile registers for the command and the result cdb CDB for packet command dma_dir Data transfer direction of the command sgl sg list for the data buffer of the command n_elem Number of sg entries timeout Timeout in msecs (0 for default) Description Executes libata internal command with timeout. tf contains command on entry and result on return. Timeout and error conditions are reported via return value. No recovery action is taken after a command times out. It's caller's duty to clean up after timeout. LOCKING None. Should be called with kernel context, might sleep. RETURNS Zero on success, AC_ERR_* mask on failure LINUX Kernel Hackers Manual July 2017 ata_exec_internal 9 4.1.27 ata_exec_internal execute libata internal command Synopsis unsigned ata_exec_internal struct ata_device * dev struct ata_taskfile * tf const u8 * cdb int dma_dir void * buf unsigned int buflen unsigned long timeout Arguments dev Device to which the command is sent tf Taskfile registers for the command and the result cdb CDB for packet command dma_dir Data transfer direction of the command buf Data buffer of the command buflen Length of data buffer timeout Timeout in msecs (0 for default) Description Wrapper around ata_exec_internal_sg which takes simple buffer instead of sg list. LOCKING None. Should be called with kernel context, might sleep. RETURNS Zero on success, AC_ERR_* mask on failure LINUX Kernel Hackers Manual July 2017 ata_pio_mask_no_iordy 9 4.1.27 ata_pio_mask_no_iordy Return the non IORDY mask Synopsis u32 ata_pio_mask_no_iordy const struct ata_device * adev Arguments adev ATA device Description Compute the highest mode possible if we are not using iordy. Return -1 if no iordy mode is available. LINUX Kernel Hackers Manual July 2017 ata_dev_read_id 9 4.1.27 ata_dev_read_id Read ID data from the specified device Synopsis int ata_dev_read_id struct ata_device * dev unsigned int * p_class unsigned int flags u16 * id Arguments dev target device p_class pointer to class of the target device (may be changed) flags ATA_READID_* flags id buffer to read IDENTIFY data into Description Read ID data from the specified device. ATA_CMD_ID_ATA is performed on ATA devices and ATA_CMD_ID_ATAPI on ATAPI devices. This function also issues ATA_CMD_INIT_DEV_PARAMS for pre-ATA4 drives. FIXME ATA_CMD_ID_ATA is optional for early drives and right now we abort if we hit that case. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno otherwise. LINUX Kernel Hackers Manual July 2017 ata_dev_configure 9 4.1.27 ata_dev_configure Configure the specified ATA/ATAPI device Synopsis int ata_dev_configure struct ata_device * dev Arguments dev Target device to configure Description Configure dev according to dev->id. Generic and low-level driver specific fixups are also applied. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, -errno otherwise LINUX Kernel Hackers Manual July 2017 ata_bus_probe 9 4.1.27 ata_bus_probe Reset and probe ATA bus Synopsis int ata_bus_probe struct ata_port * ap Arguments ap Bus to probe Description Master ATA bus probing function. Initiates a hardware-dependent bus reset, then attempts to identify any devices found on the bus. LOCKING PCI/etc. bus probe sem. RETURNS Zero on success, negative errno otherwise. LINUX Kernel Hackers Manual July 2017 sata_print_link_status 9 4.1.27 sata_print_link_status Print SATA link status Synopsis void sata_print_link_status struct ata_link * link Arguments link SATA link to printk link status about Description This function prints link speed and status of a SATA link. LOCKING None. LINUX Kernel Hackers Manual July 2017 sata_down_spd_limit 9 4.1.27 sata_down_spd_limit adjust SATA spd limit downward Synopsis int sata_down_spd_limit struct ata_link * link u32 spd_limit Arguments link Link to adjust SATA spd limit for spd_limit Additional limit Description Adjust SATA spd limit of link downward. Note that this function only adjusts the limit. The change must be applied using sata_set_spd. If spd_limit is non-zero, the speed is limited to equal to or lower than spd_limit if such speed is supported. If spd_limit is slower than any supported speed, only the lowest supported speed is allowed. LOCKING Inherited from caller. RETURNS 0 on success, negative errno on failure LINUX Kernel Hackers Manual July 2017 sata_set_spd_needed 9 4.1.27 sata_set_spd_needed is SATA spd configuration needed Synopsis int sata_set_spd_needed struct ata_link * link Arguments link Link in question Description Test whether the spd limit in SControl matches link->sata_spd_limit. This function is used to determine whether hardreset is necessary to apply SATA spd configuration. LOCKING Inherited from caller. RETURNS 1 if SATA spd configuration is needed, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_down_xfermask_limit 9 4.1.27 ata_down_xfermask_limit adjust dev xfer masks downward Synopsis int ata_down_xfermask_limit struct ata_device * dev unsigned int sel Arguments dev Device to adjust xfer masks sel ATA_DNXFER_* selector Description Adjust xfer masks of dev downward. Note that this function does not apply the change. Invoking ata_set_mode afterwards will apply the limit. LOCKING Inherited from caller. RETURNS 0 on success, negative errno on failure LINUX Kernel Hackers Manual July 2017 ata_wait_ready 9 4.1.27 ata_wait_ready wait for link to become ready Synopsis int ata_wait_ready struct ata_link * link unsigned long deadline int (*check_ready) struct ata_link *link Arguments link link to be waited on deadline deadline jiffies for the operation check_ready callback to check link readiness Description Wait for link to become ready. check_ready should return positive number if link is ready, 0 if it isn't, -ENODEV if link doesn't seem to be occupied, other errno for other error conditions. Transient -ENODEV conditions are allowed for ATA_TMOUT_FF_WAIT. LOCKING EH context. RETURNS 0 if linke is ready before deadline; otherwise, -errno. LINUX Kernel Hackers Manual July 2017 ata_dev_same_device 9 4.1.27 ata_dev_same_device Determine whether new ID matches configured device Synopsis int ata_dev_same_device struct ata_device * dev unsigned int new_class const u16 * new_id Arguments dev device to compare against new_class class of the new device new_id IDENTIFY page of the new device Description Compare new_class and new_id against dev and determine whether dev is the device indicated by new_class and new_id. LOCKING None. RETURNS 1 if dev matches new_class and new_id, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_dev_reread_id 9 4.1.27 ata_dev_reread_id Re-read IDENTIFY data Synopsis int ata_dev_reread_id struct ata_device * dev unsigned int readid_flags Arguments dev target ATA device readid_flags read ID flags Description Re-read IDENTIFY page and make sure dev is still attached to the port. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, negative errno otherwise LINUX Kernel Hackers Manual July 2017 ata_dev_revalidate 9 4.1.27 ata_dev_revalidate Revalidate ATA device Synopsis int ata_dev_revalidate struct ata_device * dev unsigned int new_class unsigned int readid_flags Arguments dev device to revalidate new_class new class code readid_flags read ID flags Description Re-read IDENTIFY page, make sure dev is still attached to the port and reconfigure it according to the new IDENTIFY page. LOCKING Kernel thread context (may sleep) RETURNS 0 on success, negative errno otherwise LINUX Kernel Hackers Manual July 2017 ata_is_40wire 9 4.1.27 ata_is_40wire check drive side detection Synopsis int ata_is_40wire struct ata_device * dev Arguments dev device Description Perform drive side detection decoding, allowing for device vendors who can't follow the documentation. LINUX Kernel Hackers Manual July 2017 cable_is_40wire 9 4.1.27 cable_is_40wire 40/80/SATA decider Synopsis int cable_is_40wire struct ata_port * ap Arguments ap port to consider Description This function encapsulates the policy for speed management in one place. At the moment we don't cache the result but there is a good case for setting ap->cbl to the result when we are called with unknown cables (and figuring out if it impacts hotplug at all). Return 1 if the cable appears to be 40 wire. LINUX Kernel Hackers Manual July 2017 ata_dev_xfermask 9 4.1.27 ata_dev_xfermask Compute supported xfermask of the given device Synopsis void ata_dev_xfermask struct ata_device * dev Arguments dev Device to compute xfermask for Description Compute supported xfermask of dev and store it in dev->*_mask. This function is responsible for applying all known limits including host controller limits, device blacklist, etc... LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_dev_set_xfermode 9 4.1.27 ata_dev_set_xfermode Issue SET FEATURES - XFER MODE command Synopsis unsigned int ata_dev_set_xfermode struct ata_device * dev Arguments dev Device to which command will be sent Description Issue SET FEATURES - XFER MODE command to device dev on port ap. LOCKING PCI/etc. bus probe sem. RETURNS 0 on success, AC_ERR_* mask otherwise. LINUX Kernel Hackers Manual July 2017 ata_dev_init_params 9 4.1.27 ata_dev_init_params Issue INIT DEV PARAMS command Synopsis unsigned int ata_dev_init_params struct ata_device * dev u16 heads u16 sectors Arguments dev Device to which command will be sent heads Number of heads (taskfile parameter) sectors Number of sectors (taskfile parameter) LOCKING Kernel thread context (may sleep) RETURNS 0 on success, AC_ERR_* mask otherwise. LINUX Kernel Hackers Manual July 2017 ata_sg_clean 9 4.1.27 ata_sg_clean Unmap DMA memory associated with command Synopsis void ata_sg_clean struct ata_queued_cmd * qc Arguments qc Command containing DMA memory to be released Description Unmap all mapped DMA memory associated with this command. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 atapi_check_dma 9 4.1.27 atapi_check_dma Check whether ATAPI DMA can be supported Synopsis int atapi_check_dma struct ata_queued_cmd * qc Arguments qc Metadata associated with taskfile to check Description Allow low-level driver to filter ATA PACKET commands, returning a status indicating whether or not it is OK to use DMA for the supplied PACKET command. LOCKING spin_lock_irqsave(host lock) RETURNS 0 when ATAPI DMA can be used nonzero otherwise LINUX Kernel Hackers Manual July 2017 ata_sg_setup 9 4.1.27 ata_sg_setup DMA-map the scatter-gather table associated with a command. Synopsis int ata_sg_setup struct ata_queued_cmd * qc Arguments qc Command with scatter-gather table to be mapped. Description DMA-map the scatter-gather table associated with queued_cmd qc. LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, negative on error. LINUX Kernel Hackers Manual July 2017 swap_buf_le16 9 4.1.27 swap_buf_le16 swap halves of 16-bit words in place Synopsis void swap_buf_le16 u16 * buf unsigned int buf_words Arguments buf Buffer to swap buf_words Number of 16-bit words in buffer. Description Swap halves of 16-bit words if needed to convert from little-endian byte order to native cpu byte order, or vice-versa. LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_qc_new_init 9 4.1.27 ata_qc_new_init Request an available ATA command, and initialize it Synopsis struct ata_queued_cmd * ata_qc_new_init struct ata_device * dev int tag Arguments dev Device from whom we request an available command structure tag -- undescribed -- LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_qc_free 9 4.1.27 ata_qc_free free unused ata_queued_cmd Synopsis void ata_qc_free struct ata_queued_cmd * qc Arguments qc Command to complete Description Designed to free unused ata_queued_cmd object in case something prevents using it. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_qc_issue 9 4.1.27 ata_qc_issue issue taskfile to device Synopsis void ata_qc_issue struct ata_queued_cmd * qc Arguments qc command to issue to device Description Prepare an ATA command to submission to device. This includes mapping the data into a DMA-able area, filling in the S/G table, and finally writing the taskfile to hardware, starting the command. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_phys_link_online 9 4.1.27 ata_phys_link_online test whether the given link is online Synopsis bool ata_phys_link_online struct ata_link * link Arguments link ATA link to test Description Test whether link is online. Note that this function returns 0 if online status of link cannot be obtained, so ata_link_online(link) != !ata_link_offline(link). LOCKING None. RETURNS True if the port online status is available and online. LINUX Kernel Hackers Manual July 2017 ata_phys_link_offline 9 4.1.27 ata_phys_link_offline test whether the given link is offline Synopsis bool ata_phys_link_offline struct ata_link * link Arguments link ATA link to test Description Test whether link is offline. Note that this function returns 0 if offline status of link cannot be obtained, so ata_link_online(link) != !ata_link_offline(link). LOCKING None. RETURNS True if the port offline status is available and offline. LINUX Kernel Hackers Manual July 2017 ata_dev_init 9 4.1.27 ata_dev_init Initialize an ata_device structure Synopsis void ata_dev_init struct ata_device * dev Arguments dev Device structure to initialize Description Initialize dev in preparation for probing. LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_link_init 9 4.1.27 ata_link_init Initialize an ata_link structure Synopsis void ata_link_init struct ata_port * ap struct ata_link * link int pmp Arguments ap ATA port link is attached to link Link structure to initialize pmp Port multiplier port number Description Initialize link. LOCKING Kernel thread context (may sleep) LINUX Kernel Hackers Manual July 2017 sata_link_init_spd 9 4.1.27 sata_link_init_spd Initialize link->sata_spd_limit Synopsis int sata_link_init_spd struct ata_link * link Arguments link Link to configure sata_spd_limit for Description Initialize link->[hw_]sata_spd_limit to the currently configured value. LOCKING Kernel thread context (may sleep). RETURNS 0 on success, -errno on failure. LINUX Kernel Hackers Manual July 2017 ata_port_alloc 9 4.1.27 ata_port_alloc allocate and initialize basic ATA port resources Synopsis struct ata_port * ata_port_alloc struct ata_host * host Arguments host ATA host this allocated port belongs to Description Allocate and initialize basic ATA port resources. RETURNS Allocate ATA port on success, NULL on failure. LOCKING Inherited from calling layer (may sleep). LINUX Kernel Hackers Manual July 2017 ata_finalize_port_ops 9 4.1.27 ata_finalize_port_ops finalize ata_port_operations Synopsis void ata_finalize_port_ops struct ata_port_operations * ops Arguments ops ata_port_operations to finalize Description An ata_port_operations can inherit from another ops and that ops can again inherit from another. This can go on as many times as necessary as long as there is no loop in the inheritance chain. Ops tables are finalized when the host is started. NULL or unspecified entries are inherited from the closet ancestor which has the method and the entry is populated with it. After finalization, the ops table directly points to all the methods and ->inherits is no longer necessary and cleared. Using ATA_OP_NULL, inheriting ops can force a method to NULL. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_port_detach 9 4.1.27 ata_port_detach Detach ATA port in prepration of device removal Synopsis void ata_port_detach struct ata_port * ap Arguments ap ATA port to be detached Description Detach all ATA devices and the associated SCSI devices of ap; then, remove the associated SCSI host. ap is guaranteed to be quiescent on return from this function. LOCKING Kernel thread context (may sleep). libata SCSI translation/emulation LINUX Kernel Hackers Manual July 2017 ata_std_bios_param 9 4.1.27 ata_std_bios_param generic bios head/sector/cylinder calculator used by sd. Synopsis int ata_std_bios_param struct scsi_device * sdev struct block_device * bdev sector_t capacity int geom[] Arguments sdev SCSI device for which BIOS geometry is to be determined bdev block device associated with sdev capacity capacity of SCSI device geom[] location to which geometry will be output Description Generic bios head/sector/cylinder calculator used by sd. Most BIOSes nowadays expect a XXX/255/16 (CHS) mapping. Some situations may arise where the disk is not bootable if this is not used. LOCKING Defined by the SCSI layer. We don't really care. RETURNS Zero. LINUX Kernel Hackers Manual July 2017 ata_scsi_unlock_native_capacity 9 4.1.27 ata_scsi_unlock_native_capacity unlock native capacity Synopsis void ata_scsi_unlock_native_capacity struct scsi_device * sdev Arguments sdev SCSI device to adjust device capacity for Description This function is called if a partition on sdev extends beyond the end of the device. It requests EH to unlock HPA. LOCKING Defined by the SCSI layer. Might sleep. LINUX Kernel Hackers Manual July 2017 ata_scsi_slave_config 9 4.1.27 ata_scsi_slave_config Set SCSI device attributes Synopsis int ata_scsi_slave_config struct scsi_device * sdev Arguments sdev SCSI device to examine Description This is called before we actually start reading and writing to the device, to configure certain SCSI mid-layer behaviors. LOCKING Defined by SCSI layer. We don't really care. LINUX Kernel Hackers Manual July 2017 ata_scsi_slave_destroy 9 4.1.27 ata_scsi_slave_destroy SCSI device is about to be destroyed Synopsis void ata_scsi_slave_destroy struct scsi_device * sdev Arguments sdev SCSI device to be destroyed Description sdev is about to be destroyed for hot/warm unplugging. If this unplugging was initiated by libata as indicated by NULL dev->sdev, this function doesn't have to do anything. Otherwise, SCSI layer initiated warm-unplug is in progress. Clear dev->sdev, schedule the device for ATA detach and invoke EH. LOCKING Defined by SCSI layer. We don't really care. LINUX Kernel Hackers Manual July 2017 __ata_change_queue_depth 9 4.1.27 __ata_change_queue_depth helper for ata_scsi_change_queue_depth Synopsis int __ata_change_queue_depth struct ata_port * ap struct scsi_device * sdev int queue_depth Arguments ap ATA port to which the device change the queue depth sdev SCSI device to configure queue depth for queue_depth new queue depth Description libsas and libata have different approaches for associating a sdev to its ata_port. LINUX Kernel Hackers Manual July 2017 ata_scsi_change_queue_depth 9 4.1.27 ata_scsi_change_queue_depth SCSI callback for queue depth config Synopsis int ata_scsi_change_queue_depth struct scsi_device * sdev int queue_depth Arguments sdev SCSI device to configure queue depth for queue_depth new queue depth Description This is libata standard hostt->change_queue_depth callback. SCSI will call into this callback when user tries to set queue depth via sysfs. LOCKING SCSI layer (we don't care) RETURNS Newly configured queue depth. LINUX Kernel Hackers Manual July 2017 ata_scsi_queuecmd 9 4.1.27 ata_scsi_queuecmd Issue SCSI cdb to libata-managed device Synopsis int ata_scsi_queuecmd struct Scsi_Host * shost struct scsi_cmnd * cmd Arguments shost SCSI host of command to be sent cmd SCSI command to be sent Description In some cases, this function translates SCSI commands into ATA taskfiles, and queues the taskfiles to be sent to hardware. In other cases, this function simulates a SCSI device by evaluating and responding to certain SCSI commands. This creates the overall effect of ATA and ATAPI devices appearing as SCSI devices. LOCKING ATA host lock RETURNS Return value from __ata_scsi_queuecmd if cmd can be queued, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_scsi_simulate 9 4.1.27 ata_scsi_simulate simulate SCSI command on ATA device Synopsis void ata_scsi_simulate struct ata_device * dev struct scsi_cmnd * cmd Arguments dev the target device cmd SCSI command being sent to device. Description Interprets and directly executes a select list of SCSI commands that can be handled internally. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_sas_port_alloc 9 4.1.27 ata_sas_port_alloc Allocate port for a SAS attached SATA device Synopsis struct ata_port * ata_sas_port_alloc struct ata_host * host struct ata_port_info * port_info struct Scsi_Host * shost Arguments host ATA host container for all SAS ports port_info Information from low-level host driver shost SCSI host that the scsi device is attached to LOCKING PCI/etc. bus probe sem. RETURNS ata_port pointer on success / NULL on failure. LINUX Kernel Hackers Manual July 2017 ata_sas_port_start 9 4.1.27 ata_sas_port_start Set port up for dma. Synopsis int ata_sas_port_start struct ata_port * ap Arguments ap Port to initialize Description Called just after data structures for each port are initialized. May be used as the port_start entry in ata_port_operations. LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_sas_port_stop 9 4.1.27 ata_sas_port_stop Undo ata_sas_port_start Synopsis void ata_sas_port_stop struct ata_port * ap Arguments ap Port to shut down Description May be used as the port_stop entry in ata_port_operations. LOCKING Inherited from caller. LINUX Kernel Hackers Manual July 2017 ata_sas_async_probe 9 4.1.27 ata_sas_async_probe simply schedule probing and return Synopsis void ata_sas_async_probe struct ata_port * ap Arguments ap Port to probe Description For batch scheduling of probe for sas attached ata devices, assumes the port has already been through ata_sas_port_init LINUX Kernel Hackers Manual July 2017 ata_sas_port_init 9 4.1.27 ata_sas_port_init Initialize a SATA device Synopsis int ata_sas_port_init struct ata_port * ap Arguments ap SATA port to initialize LOCKING PCI/etc. bus probe sem. RETURNS Zero on success, non-zero on error. LINUX Kernel Hackers Manual July 2017 ata_sas_port_destroy 9 4.1.27 ata_sas_port_destroy Destroy a SATA port allocated by ata_sas_port_alloc Synopsis void ata_sas_port_destroy struct ata_port * ap Arguments ap SATA port to destroy LINUX Kernel Hackers Manual July 2017 ata_sas_slave_configure 9 4.1.27 ata_sas_slave_configure Default slave_config routine for libata devices Synopsis int ata_sas_slave_configure struct scsi_device * sdev struct ata_port * ap Arguments sdev SCSI device to configure ap ATA port to which SCSI device is attached RETURNS Zero. LINUX Kernel Hackers Manual July 2017 ata_sas_queuecmd 9 4.1.27 ata_sas_queuecmd Issue SCSI cdb to libata-managed device Synopsis int ata_sas_queuecmd struct scsi_cmnd * cmd struct ata_port * ap Arguments cmd SCSI command to be sent ap ATA port to which the command is being sent RETURNS Return value from __ata_scsi_queuecmd if cmd can be queued, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_get_identity 9 4.1.27 ata_get_identity Handler for HDIO_GET_IDENTITY ioctl Synopsis int ata_get_identity struct ata_port * ap struct scsi_device * sdev void __user * arg Arguments ap target port sdev SCSI device to get identify data for arg User buffer area for identify data LOCKING Defined by the SCSI layer. We don't really care. RETURNS Zero on success, negative errno on error. LINUX Kernel Hackers Manual July 2017 ata_cmd_ioctl 9 4.1.27 ata_cmd_ioctl Handler for HDIO_DRIVE_CMD ioctl Synopsis int ata_cmd_ioctl struct scsi_device * scsidev void __user * arg Arguments scsidev Device to which we are issuing command arg User provided data for issuing command LOCKING Defined by the SCSI layer. We don't really care. RETURNS Zero on success, negative errno on error. LINUX Kernel Hackers Manual July 2017 ata_task_ioctl 9 4.1.27 ata_task_ioctl Handler for HDIO_DRIVE_TASK ioctl Synopsis int ata_task_ioctl struct scsi_device * scsidev void __user * arg Arguments scsidev Device to which we are issuing command arg User provided data for issuing command LOCKING Defined by the SCSI layer. We don't really care. RETURNS Zero on success, negative errno on error. LINUX Kernel Hackers Manual July 2017 ata_scsi_qc_new 9 4.1.27 ata_scsi_qc_new acquire new ata_queued_cmd reference Synopsis struct ata_queued_cmd * ata_scsi_qc_new struct ata_device * dev struct scsi_cmnd * cmd Arguments dev ATA device to which the new command is attached cmd SCSI command that originated this ATA command Description Obtain a reference to an unused ata_queued_cmd structure, which is the basic libata structure representing a single ATA command sent to the hardware. If a command was available, fill in the SCSI-specific portions of the structure with information on the current command. LOCKING spin_lock_irqsave(host lock) RETURNS Command allocated, or NULL if none available. LINUX Kernel Hackers Manual July 2017 ata_dump_status 9 4.1.27 ata_dump_status user friendly display of error info Synopsis void ata_dump_status unsigned id struct ata_taskfile * tf Arguments id id of the port in question tf ptr to filled out taskfile Description Decode and dump the ATA error/status registers for the user so that they have some idea what really happened at the non make-believe layer. LOCKING inherited from caller LINUX Kernel Hackers Manual July 2017 ata_to_sense_error 9 4.1.27 ata_to_sense_error convert ATA error to SCSI error Synopsis void ata_to_sense_error unsigned id u8 drv_stat u8 drv_err u8 * sk u8 * asc u8 * ascq int verbose Arguments id ATA device number drv_stat value contained in ATA status register drv_err value contained in ATA error register sk the sense key we'll fill out asc the additional sense code we'll fill out ascq the additional sense code qualifier we'll fill out verbose be verbose Description Converts an ATA error into a SCSI error. Fill out pointers to SK, ASC, and ASCQ bytes for later use in fixed or descriptor format sense blocks. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_gen_ata_sense 9 4.1.27 ata_gen_ata_sense generate a SCSI fixed sense block Synopsis void ata_gen_ata_sense struct ata_queued_cmd * qc Arguments qc Command that we are erroring out Description Generate sense block for a failed ATA command qc. Descriptor format is used to accommodate LBA48 block address. LOCKING None. LINUX Kernel Hackers Manual July 2017 atapi_drain_needed 9 4.1.27 atapi_drain_needed Check whether data transfer may overflow Synopsis int atapi_drain_needed struct request * rq Arguments rq request to be checked Description ATAPI commands which transfer variable length data to host might overflow due to application error or hardare bug. This function checks whether overflow should be drained and ignored for request. LOCKING None. RETURNS 1 if ; otherwise, 0. LINUX Kernel Hackers Manual July 2017 ata_scsi_start_stop_xlat 9 4.1.27 ata_scsi_start_stop_xlat Translate SCSI START STOP UNIT command Synopsis unsigned int ata_scsi_start_stop_xlat struct ata_queued_cmd * qc Arguments qc Storage for translated ATA taskfile Description Sets up an ATA taskfile to issue STANDBY (to stop) or READ VERIFY (to start). Perhaps these commands should be preceded by CHECK POWER MODE to see what power mode the device is already in. [See SAT revision 5 at www.t10.org] LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, non-zero on error. LINUX Kernel Hackers Manual July 2017 ata_scsi_flush_xlat 9 4.1.27 ata_scsi_flush_xlat Translate SCSI SYNCHRONIZE CACHE command Synopsis unsigned int ata_scsi_flush_xlat struct ata_queued_cmd * qc Arguments qc Storage for translated ATA taskfile Description Sets up an ATA taskfile to issue FLUSH CACHE or FLUSH CACHE EXT. LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, non-zero on error. LINUX Kernel Hackers Manual July 2017 scsi_6_lba_len 9 4.1.27 scsi_6_lba_len Get LBA and transfer length Synopsis void scsi_6_lba_len const u8 * cdb u64 * plba u32 * plen Arguments cdb SCSI command to translate plba the LBA plen the transfer length Description Calculate LBA and transfer length for 6-byte commands. LINUX Kernel Hackers Manual July 2017 scsi_10_lba_len 9 4.1.27 scsi_10_lba_len Get LBA and transfer length Synopsis void scsi_10_lba_len const u8 * cdb u64 * plba u32 * plen Arguments cdb SCSI command to translate plba the LBA plen the transfer length Description Calculate LBA and transfer length for 10-byte commands. LINUX Kernel Hackers Manual July 2017 scsi_16_lba_len 9 4.1.27 scsi_16_lba_len Get LBA and transfer length Synopsis void scsi_16_lba_len const u8 * cdb u64 * plba u32 * plen Arguments cdb SCSI command to translate plba the LBA plen the transfer length Description Calculate LBA and transfer length for 16-byte commands. LINUX Kernel Hackers Manual July 2017 ata_scsi_verify_xlat 9 4.1.27 ata_scsi_verify_xlat Translate SCSI VERIFY command into an ATA one Synopsis unsigned int ata_scsi_verify_xlat struct ata_queued_cmd * qc Arguments qc Storage for translated ATA taskfile Description Converts SCSI VERIFY command to an ATA READ VERIFY command. LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, non-zero on error. LINUX Kernel Hackers Manual July 2017 ata_scsi_rw_xlat 9 4.1.27 ata_scsi_rw_xlat Translate SCSI r/w command into an ATA one Synopsis unsigned int ata_scsi_rw_xlat struct ata_queued_cmd * qc Arguments qc Storage for translated ATA taskfile Description Converts any of six SCSI read/write commands into the ATA counterpart, including starting sector (LBA), sector count, and taking into account the device's LBA48 support. Commands READ_6, READ_10, READ_16, WRITE_6, WRITE_10, and WRITE_16 are currently supported. LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, non-zero on error. LINUX Kernel Hackers Manual July 2017 ata_scsi_translate 9 4.1.27 ata_scsi_translate Translate then issue SCSI command to ATA device Synopsis int ata_scsi_translate struct ata_device * dev struct scsi_cmnd * cmd ata_xlat_func_t xlat_func Arguments dev ATA device to which the command is addressed cmd SCSI command to execute xlat_func Actor which translates cmd to an ATA taskfile Description Our ->queuecommand function has decided that the SCSI command issued can be directly translated into an ATA command, rather than handled internally. This function sets up an ata_queued_cmd structure for the SCSI command, and sends that ata_queued_cmd to the hardware. The xlat_func argument (actor) returns 0 if ready to execute ATA command, else 1 to finish translation. If 1 is returned then cmd->result (and possibly cmd->sense_buffer) are assumed to be set reflecting an error condition or clean (early) termination. LOCKING spin_lock_irqsave(host lock) RETURNS 0 on success, SCSI_ML_QUEUE_DEVICE_BUSY if the command needs to be deferred. LINUX Kernel Hackers Manual July 2017 ata_scsi_rbuf_get 9 4.1.27 ata_scsi_rbuf_get Map response buffer. Synopsis void * ata_scsi_rbuf_get struct scsi_cmnd * cmd bool copy_in unsigned long * flags Arguments cmd SCSI command containing buffer to be mapped. copy_in copy in from user buffer flags unsigned long variable to store irq enable status Description Prepare buffer for simulated SCSI commands. LOCKING spin_lock_irqsave(ata_scsi_rbuf_lock) on success RETURNS Pointer to response buffer. LINUX Kernel Hackers Manual July 2017 ata_scsi_rbuf_put 9 4.1.27 ata_scsi_rbuf_put Unmap response buffer. Synopsis void ata_scsi_rbuf_put struct scsi_cmnd * cmd bool copy_out unsigned long * flags Arguments cmd SCSI command containing buffer to be unmapped. copy_out copy out result flags flags passed to ata_scsi_rbuf_get Description Returns rbuf buffer. The result is copied to cmd's buffer if copy_back is true. LOCKING Unlocks ata_scsi_rbuf_lock. LINUX Kernel Hackers Manual July 2017 ata_scsi_rbuf_fill 9 4.1.27 ata_scsi_rbuf_fill wrapper for SCSI command simulators Synopsis void ata_scsi_rbuf_fill struct ata_scsi_args * args unsigned int (*actor) struct ata_scsi_args *args, u8 *rbuf Arguments args device IDENTIFY data / SCSI command of interest. actor Callback hook for desired SCSI command simulator Description Takes care of the hard work of simulating a SCSI command... Mapping the response buffer, calling the command's handler, and handling the handler's return value. This return value indicates whether the handler wishes the SCSI command to be completed successfully (0), or not (in which case cmd->result and sense buffer are assumed to be set). LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_inq_std 9 4.1.27 ata_scsiop_inq_std Simulate INQUIRY command Synopsis unsigned int ata_scsiop_inq_std struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Returns standard device identification data associated with non-VPD INQUIRY command output. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_inq_00 9 4.1.27 ata_scsiop_inq_00 Simulate INQUIRY VPD page 0, list of pages Synopsis unsigned int ata_scsiop_inq_00 struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Returns list of inquiry VPD pages available. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_inq_80 9 4.1.27 ata_scsiop_inq_80 Simulate INQUIRY VPD page 80, device serial number Synopsis unsigned int ata_scsiop_inq_80 struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Returns ATA device serial number. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_inq_83 9 4.1.27 ata_scsiop_inq_83 Simulate INQUIRY VPD page 83, device identity Synopsis unsigned int ata_scsiop_inq_83 struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Yields two logical unit device identification designators - vendor specific ASCII containing the ATA serial number - SAT defined t10 vendor id based containing ASCII vendor name (ATA ), model and serial numbers. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_inq_89 9 4.1.27 ata_scsiop_inq_89 Simulate INQUIRY VPD page 89, ATA info Synopsis unsigned int ata_scsiop_inq_89 struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Yields SAT-specified ATA VPD page. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_noop 9 4.1.27 ata_scsiop_noop Command handler that simply returns success. Synopsis unsigned int ata_scsiop_noop struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description No operation. Simply returns success to caller, to indicate that the caller should successfully complete this SCSI command. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 modecpy 9 4.1.27 modecpy Prepare response for MODE SENSE Synopsis void modecpy u8 * dest const u8 * src int n bool changeable Arguments dest output buffer src data being copied n length of mode page changeable whether changeable parameters are requested Description Generate a generic MODE SENSE page for either current or changeable parameters. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_msense_caching 9 4.1.27 ata_msense_caching Simulate MODE SENSE caching info page Synopsis unsigned int ata_msense_caching u16 * id u8 * buf bool changeable Arguments id device IDENTIFY data buf output buffer changeable whether changeable parameters are requested Description Generate a caching info page, which conditionally indicates write caching to the SCSI layer, depending on device capabilities. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_msense_ctl_mode 9 4.1.27 ata_msense_ctl_mode Simulate MODE SENSE control mode page Synopsis unsigned int ata_msense_ctl_mode u8 * buf bool changeable Arguments buf output buffer changeable whether changeable parameters are requested Description Generate a generic MODE SENSE control mode page. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_msense_rw_recovery 9 4.1.27 ata_msense_rw_recovery Simulate MODE SENSE r/w error recovery page Synopsis unsigned int ata_msense_rw_recovery u8 * buf bool changeable Arguments buf output buffer changeable whether changeable parameters are requested Description Generate a generic MODE SENSE r/w error recovery page. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_scsiop_mode_sense 9 4.1.27 ata_scsiop_mode_sense Simulate MODE SENSE 6, 10 commands Synopsis unsigned int ata_scsiop_mode_sense struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Simulate MODE SENSE commands. Assume this is invoked for direct access devices (e.g. disks) only. There should be no block descriptor for other device types. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsiop_read_cap 9 4.1.27 ata_scsiop_read_cap Simulate READ CAPACITY[ 16] commands Synopsis unsigned int ata_scsiop_read_cap struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Simulate READ CAPACITY commands. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_scsiop_report_luns 9 4.1.27 ata_scsiop_report_luns Simulate REPORT LUNS command Synopsis unsigned int ata_scsiop_report_luns struct ata_scsi_args * args u8 * rbuf Arguments args device IDENTIFY data / SCSI command of interest. rbuf Response buffer, to which simulated SCSI cmd output is sent. Description Simulate REPORT LUNS command. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 atapi_xlat 9 4.1.27 atapi_xlat Initialize PACKET taskfile Synopsis unsigned int atapi_xlat struct ata_queued_cmd * qc Arguments qc command structure to be initialized LOCKING spin_lock_irqsave(host lock) RETURNS Zero on success, non-zero on failure. LINUX Kernel Hackers Manual July 2017 ata_scsi_find_dev 9 4.1.27 ata_scsi_find_dev lookup ata_device from scsi_cmnd Synopsis struct ata_device * ata_scsi_find_dev struct ata_port * ap const struct scsi_device * scsidev Arguments ap ATA port to which the device is attached scsidev SCSI device from which we derive the ATA device Description Given various information provided in struct scsi_cmnd, map that onto an ATA bus, and using that mapping determine which ata_device is associated with the SCSI command to be sent. LOCKING spin_lock_irqsave(host lock) RETURNS Associated ATA device, or NULL if not found. LINUX Kernel Hackers Manual July 2017 ata_scsi_pass_thru 9 4.1.27 ata_scsi_pass_thru convert ATA pass-thru CDB to taskfile Synopsis unsigned int ata_scsi_pass_thru struct ata_queued_cmd * qc Arguments qc command structure to be initialized Description Handles either 12 or 16-byte versions of the CDB. RETURNS Zero on success, non-zero on failure. LINUX Kernel Hackers Manual July 2017 ata_mselect_caching 9 4.1.27 ata_mselect_caching Simulate MODE SELECT for caching info page Synopsis int ata_mselect_caching struct ata_queued_cmd * qc const u8 * buf int len Arguments qc Storage for translated ATA taskfile buf input buffer len number of valid bytes in the input buffer Description Prepare a taskfile to modify caching information for the device. LOCKING None. LINUX Kernel Hackers Manual July 2017 ata_scsi_mode_select_xlat 9 4.1.27 ata_scsi_mode_select_xlat Simulate MODE SELECT 6, 10 commands Synopsis unsigned int ata_scsi_mode_select_xlat struct ata_queued_cmd * qc Arguments qc Storage for translated ATA taskfile Description Converts a MODE SELECT command to an ATA SET FEATURES taskfile. Assume this is invoked for direct access devices (e.g. disks) only. There should be no block descriptor for other device types. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_get_xlat_func 9 4.1.27 ata_get_xlat_func check if SCSI to ATA translation is possible Synopsis ata_xlat_func_t ata_get_xlat_func struct ata_device * dev u8 cmd Arguments dev ATA device cmd SCSI command opcode to consider Description Look up the SCSI command given, and determine whether the SCSI command is to be translated or simulated. RETURNS Pointer to translation function if possible, NULL if not. LINUX Kernel Hackers Manual July 2017 ata_scsi_dump_cdb 9 4.1.27 ata_scsi_dump_cdb dump SCSI command contents to dmesg Synopsis void ata_scsi_dump_cdb struct ata_port * ap struct scsi_cmnd * cmd Arguments ap ATA port to which the command was being sent cmd SCSI command to dump Description Prints the contents of a SCSI command via printk. LINUX Kernel Hackers Manual July 2017 ata_scsi_offline_dev 9 4.1.27 ata_scsi_offline_dev offline attached SCSI device Synopsis int ata_scsi_offline_dev struct ata_device * dev Arguments dev ATA device to offline attached SCSI device for Description This function is called from ata_eh_hotplug and responsible for taking the SCSI device attached to dev offline. This function is called with host lock which protects dev->sdev against clearing. LOCKING spin_lock_irqsave(host lock) RETURNS 1 if attached SCSI device exists, 0 otherwise. LINUX Kernel Hackers Manual July 2017 ata_scsi_remove_dev 9 4.1.27 ata_scsi_remove_dev remove attached SCSI device Synopsis void ata_scsi_remove_dev struct ata_device * dev Arguments dev ATA device to remove attached SCSI device for Description This function is called from ata_eh_scsi_hotplug and responsible for removing the SCSI device attached to dev. LOCKING Kernel thread context (may sleep). LINUX Kernel Hackers Manual July 2017 ata_scsi_media_change_notify 9 4.1.27 ata_scsi_media_change_notify send media change event Synopsis void ata_scsi_media_change_notify struct ata_device * dev Arguments dev Pointer to the disk device with media change event Description Tell the block layer to send a media change notification event. LOCKING spin_lock_irqsave(host lock) LINUX Kernel Hackers Manual July 2017 ata_scsi_hotplug 9 4.1.27 ata_scsi_hotplug SCSI part of hotplug Synopsis void ata_scsi_hotplug struct work_struct * work Arguments work Pointer to ATA port to perform SCSI hotplug on Description Perform SCSI part of hotplug. It's executed from a separate workqueue after EH completes. This is necessary because SCSI hot plugging requires working EH and hot unplugging is synchronized with hot plugging with a mutex. LOCKING Kernel thread context (may sleep). LINUX Kernel Hackers Manual July 2017 ata_scsi_user_scan 9 4.1.27 ata_scsi_user_scan indication for user-initiated bus scan Synopsis int ata_scsi_user_scan struct Scsi_Host * shost unsigned int channel unsigned int id u64 lun Arguments shost SCSI host to scan channel Channel to scan id ID to scan lun LUN to scan Description This function is called when user explicitly requests bus scan. Set probe pending flag and invoke EH. LOCKING SCSI layer (we don't care) RETURNS Zero. LINUX Kernel Hackers Manual July 2017 ata_scsi_dev_rescan 9 4.1.27 ata_scsi_dev_rescan initiate scsi_rescan_device Synopsis void ata_scsi_dev_rescan struct work_struct * work Arguments work Pointer to ATA port to perform scsi_rescan_device Description After ATA pass thru (SAT) commands are executed successfully, libata need to propagate the changes to SCSI layer. LOCKING Kernel thread context (may sleep). ATA errors and exceptions This chapter tries to identify what error/exception conditions exist for ATA/ATAPI devices and describe how they should be handled in implementation-neutral way. The term 'error' is used to describe conditions where either an explicit error condition is reported from device or a command has timed out. The term 'exception' is either used to describe exceptional conditions which are not errors (say, power or hotplug events), or to describe both errors and non-error exceptional conditions. Where explicit distinction between error and exception is necessary, the term 'non-error exception' is used. Exception categories Exceptions are described primarily with respect to legacy taskfile + bus master IDE interface. If a controller provides other better mechanism for error reporting, mapping those into categories described below shouldn't be difficult. In the following sections, two recovery actions - reset and reconfiguring transport - are mentioned. These are described further in . HSM violation This error is indicated when STATUS value doesn't match HSM requirement during issuing or execution any ATA/ATAPI command. Examples ATA_STATUS doesn't contain !BSY && DRDY && !DRQ while trying to issue a command. !BSY && !DRQ during PIO data transfer. DRQ on command completion. !BSY && ERR after CDB transfer starts but before the last byte of CDB is transferred. ATA/ATAPI standard states that "The device shall not terminate the PACKET command with an error before the last byte of the command packet has been written" in the error outputs description of PACKET command and the state diagram doesn't include such transitions. In these cases, HSM is violated and not much information regarding the error can be acquired from STATUS or ERROR register. IOW, this error can be anything - driver bug, faulty device, controller and/or cable. As HSM is violated, reset is necessary to restore known state. Reconfiguring transport for lower speed might be helpful too as transmission errors sometimes cause this kind of errors. ATA/ATAPI device error (non-NCQ / non-CHECK CONDITION) These are errors detected and reported by ATA/ATAPI devices indicating device problems. For this type of errors, STATUS and ERROR register values are valid and describe error condition. Note that some of ATA bus errors are detected by ATA/ATAPI devices and reported using the same mechanism as device errors. Those cases are described later in this section. For ATA commands, this type of errors are indicated by !BSY && ERR during command execution and on completion. For ATAPI commands, !BSY && ERR && ABRT right after issuing PACKET indicates that PACKET command is not supported and falls in this category. !BSY && ERR(==CHK) && !ABRT after the last byte of CDB is transferred indicates CHECK CONDITION and doesn't fall in this category. !BSY && ERR(==CHK) && ABRT after the last byte of CDB is transferred *probably* indicates CHECK CONDITION and doesn't fall in this category. Of errors detected as above, the followings are not ATA/ATAPI device errors but ATA bus errors and should be handled according to . CRC error during data transfer This is indicated by ICRC bit in the ERROR register and means that corruption occurred during data transfer. Up to ATA/ATAPI-7, the standard specifies that this bit is only applicable to UDMA transfers but ATA/ATAPI-8 draft revision 1f says that the bit may be applicable to multiword DMA and PIO. ABRT error during data transfer or on completion Up to ATA/ATAPI-7, the standard specifies that ABRT could be set on ICRC errors and on cases where a device is not able to complete a command. Combined with the fact that MWDMA and PIO transfer errors aren't allowed to use ICRC bit up to ATA/ATAPI-7, it seems to imply that ABRT bit alone could indicate transfer errors. However, ATA/ATAPI-8 draft revision 1f removes the part that ICRC errors can turn on ABRT. So, this is kind of gray area. Some heuristics are needed here. ATA/ATAPI device errors can be further categorized as follows. Media errors This is indicated by UNC bit in the ERROR register. ATA devices reports UNC error only after certain number of retries cannot recover the data, so there's nothing much else to do other than notifying upper layer. READ and WRITE commands report CHS or LBA of the first failed sector but ATA/ATAPI standard specifies that the amount of transferred data on error completion is indeterminate, so we cannot assume that sectors preceding the failed sector have been transferred and thus cannot complete those sectors successfully as SCSI does. Media changed / media change requested error <<TODO: fill here>> Address error This is indicated by IDNF bit in the ERROR register. Report to upper layer. Other errors This can be invalid command or parameter indicated by ABRT ERROR bit or some other error condition. Note that ABRT bit can indicate a lot of things including ICRC and Address errors. Heuristics needed. Depending on commands, not all STATUS/ERROR bits are applicable. These non-applicable bits are marked with "na" in the output descriptions but up to ATA/ATAPI-7 no definition of "na" can be found. However, ATA/ATAPI-8 draft revision 1f describes "N/A" as follows.
3.2.3.3a N/A A keyword the indicates a field has no defined value in this standard and should not be checked by the host or device. N/A fields should be cleared to zero.
So, it seems reasonable to assume that "na" bits are cleared to zero by devices and thus need no explicit masking. ATAPI device CHECK CONDITION ATAPI device CHECK CONDITION error is indicated by set CHK bit (ERR bit) in the STATUS register after the last byte of CDB is transferred for a PACKET command. For this kind of errors, sense data should be acquired to gather information regarding the errors. REQUEST SENSE packet command should be used to acquire sense data. Once sense data is acquired, this type of errors can be handled similarly to other SCSI errors. Note that sense data may indicate ATA bus error (e.g. Sense Key 04h HARDWARE ERROR && ASC/ASCQ 47h/00h SCSI PARITY ERROR). In such cases, the error should be considered as an ATA bus error and handled according to . ATA device error (NCQ) NCQ command error is indicated by cleared BSY and set ERR bit during NCQ command phase (one or more NCQ commands outstanding). Although STATUS and ERROR registers will contain valid values describing the error, READ LOG EXT is required to clear the error condition, determine which command has failed and acquire more information. READ LOG EXT Log Page 10h reports which tag has failed and taskfile register values describing the error. With this information the failed command can be handled as a normal ATA command error as in and all other in-flight commands must be retried. Note that this retry should not be counted - it's likely that commands retried this way would have completed normally if it were not for the failed command. Note that ATA bus errors can be reported as ATA device NCQ errors. This should be handled as described in . If READ LOG EXT Log Page 10h fails or reports NQ, we're thoroughly screwed. This condition should be treated according to . ATA bus error ATA bus error means that data corruption occurred during transmission over ATA bus (SATA or PATA). This type of errors can be indicated by ICRC or ABRT error as described in . Controller-specific error completion with error information indicating transmission error. On some controllers, command timeout. In this case, there may be a mechanism to determine that the timeout is due to transmission error. Unknown/random errors, timeouts and all sorts of weirdities. As described above, transmission errors can cause wide variety of symptoms ranging from device ICRC error to random device lockup, and, for many cases, there is no way to tell if an error condition is due to transmission error or not; therefore, it's necessary to employ some kind of heuristic when dealing with errors and timeouts. For example, encountering repetitive ABRT errors for known supported command is likely to indicate ATA bus error. Once it's determined that ATA bus errors have possibly occurred, lowering ATA bus transmission speed is one of actions which may alleviate the problem. See for more information. PCI bus error Data corruption or other failures during transmission over PCI (or other system bus). For standard BMDMA, this is indicated by Error bit in the BMDMA Status register. This type of errors must be logged as it indicates something is very wrong with the system. Resetting host controller is recommended. Late completion This occurs when timeout occurs and the timeout handler finds out that the timed out command has completed successfully or with error. This is usually caused by lost interrupts. This type of errors must be logged. Resetting host controller is recommended. Unknown error (timeout) This is when timeout occurs and the command is still processing or the host and device are in unknown state. When this occurs, HSM could be in any valid or invalid state. To bring the device to known state and make it forget about the timed out command, resetting is necessary. The timed out command may be retried. Timeouts can also be caused by transmission errors. Refer to for more details. Hotplug and power management exceptions <<TODO: fill here>> EH recovery actions This section discusses several important recovery actions. Clearing error condition Many controllers require its error registers to be cleared by error handler. Different controllers may have different requirements. For SATA, it's strongly recommended to clear at least SError register during error handling. Reset During EH, resetting is necessary in the following cases. HSM is in unknown or invalid state HBA is in unknown or invalid state EH needs to make HBA/device forget about in-flight commands HBA/device behaves weirdly Resetting during EH might be a good idea regardless of error condition to improve EH robustness. Whether to reset both or either one of HBA and device depends on situation but the following scheme is recommended. When it's known that HBA is in ready state but ATA/ATAPI device is in unknown state, reset only device. If HBA is in unknown state, reset both HBA and device. HBA resetting is implementation specific. For a controller complying to taskfile/BMDMA PCI IDE, stopping active DMA transaction may be sufficient iff BMDMA state is the only HBA context. But even mostly taskfile/BMDMA PCI IDE complying controllers may have implementation specific requirements and mechanism to reset themselves. This must be addressed by specific drivers. OTOH, ATA/ATAPI standard describes in detail ways to reset ATA/ATAPI devices. PATA hardware reset This is hardware initiated device reset signalled with asserted PATA RESET- signal. There is no standard way to initiate hardware reset from software although some hardware provides registers that allow driver to directly tweak the RESET- signal. Software reset This is achieved by turning CONTROL SRST bit on for at least 5us. Both PATA and SATA support it but, in case of SATA, this may require controller-specific support as the second Register FIS to clear SRST should be transmitted while BSY bit is still set. Note that on PATA, this resets both master and slave devices on a channel. EXECUTE DEVICE DIAGNOSTIC command Although ATA/ATAPI standard doesn't describe exactly, EDD implies some level of resetting, possibly similar level with software reset. Host-side EDD protocol can be handled with normal command processing and most SATA controllers should be able to handle EDD's just like other commands. As in software reset, EDD affects both devices on a PATA bus. Although EDD does reset devices, this doesn't suit error handling as EDD cannot be issued while BSY is set and it's unclear how it will act when device is in unknown/weird state. ATAPI DEVICE RESET command This is very similar to software reset except that reset can be restricted to the selected device without affecting the other device sharing the cable. SATA phy reset This is the preferred way of resetting a SATA device. In effect, it's identical to PATA hardware reset. Note that this can be done with the standard SCR Control register. As such, it's usually easier to implement than software reset. One more thing to consider when resetting devices is that resetting clears certain configuration parameters and they need to be set to their previous or newly adjusted values after reset. Parameters affected are. CHS set up with INITIALIZE DEVICE PARAMETERS (seldom used) Parameters set with SET FEATURES including transfer mode setting Block count set with SET MULTIPLE MODE Other parameters (SET MAX, MEDIA LOCK...) ATA/ATAPI standard specifies that some parameters must be maintained across hardware or software reset, but doesn't strictly specify all of them. Always reconfiguring needed parameters after reset is required for robustness. Note that this also applies when resuming from deep sleep (power-off). Also, ATA/ATAPI standard requires that IDENTIFY DEVICE / IDENTIFY PACKET DEVICE is issued after any configuration parameter is updated or a hardware reset and the result used for further operation. OS driver is required to implement revalidation mechanism to support this. Reconfigure transport For both PATA and SATA, a lot of corners are cut for cheap connectors, cables or controllers and it's quite common to see high transmission error rate. This can be mitigated by lowering transmission speed. The following is a possible scheme Jeff Garzik suggested.
If more than $N (3?) transmission errors happen in 15 minutes, if SATA, decrease SATA PHY speed. if speed cannot be decreased, decrease UDMA xfer speed. if at UDMA0, switch to PIO4, decrease PIO xfer speed. if at PIO3, complain, but continue
ata_piix Internals LINUX Kernel Hackers Manual July 2017 ich_pata_cable_detect 9 4.1.27 ich_pata_cable_detect Probe host controller cable detect info Synopsis int ich_pata_cable_detect struct ata_port * ap Arguments ap Port for which cable detect info is desired Description Read 80c cable indicator from ATA PCI device's PCI config register. This register is normally set by firmware (BIOS). LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 piix_pata_prereset 9 4.1.27 piix_pata_prereset prereset for PATA host controller Synopsis int piix_pata_prereset struct ata_link * link unsigned long deadline Arguments link Target link deadline deadline jiffies for the operation LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 piix_set_piomode 9 4.1.27 piix_set_piomode Initialize host controller PATA PIO timings Synopsis void piix_set_piomode struct ata_port * ap struct ata_device * adev Arguments ap Port whose timings we are configuring adev Drive in question Description Set PIO mode for device, in host controller PCI config space. LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 do_pata_set_dmamode 9 4.1.27 do_pata_set_dmamode Initialize host controller PATA PIO timings Synopsis void do_pata_set_dmamode struct ata_port * ap struct ata_device * adev int isich Arguments ap Port whose timings we are configuring adev Drive in question isich set if the chip is an ICH device Description Set UDMA mode for device, in host controller PCI config space. LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 piix_set_dmamode 9 4.1.27 piix_set_dmamode Initialize host controller PATA DMA timings Synopsis void piix_set_dmamode struct ata_port * ap struct ata_device * adev Arguments ap Port whose timings we are configuring adev um Description Set MW/UDMA mode for device, in host controller PCI config space. LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 ich_set_dmamode 9 4.1.27 ich_set_dmamode Initialize host controller PATA DMA timings Synopsis void ich_set_dmamode struct ata_port * ap struct ata_device * adev Arguments ap Port whose timings we are configuring adev um Description Set MW/UDMA mode for device, in host controller PCI config space. LOCKING None (inherited from caller). LINUX Kernel Hackers Manual July 2017 piix_check_450nx_errata 9 4.1.27 piix_check_450nx_errata Check for problem 450NX setup Synopsis int piix_check_450nx_errata struct pci_dev * ata_dev Arguments ata_dev the PCI device to check Description Check for the present of 450NX errata #19 and errata #25. If they are found return an error code so we can turn off DMA LINUX Kernel Hackers Manual July 2017 piix_init_one 9 4.1.27 piix_init_one Register PIIX ATA PCI device with kernel services Synopsis int piix_init_one struct pci_dev * pdev const struct pci_device_id * ent Arguments pdev PCI device to register ent Entry in piix_pci_tbl matching with pdev Description Called from kernel PCI layer. We probe for combined mode (sigh), and then hand over control to libata, for it to do the rest. LOCKING Inherited from PCI layer (may sleep). RETURNS Zero on success, or -ERRNO value. sata_sil Internals LINUX Kernel Hackers Manual July 2017 sil_set_mode 9 4.1.27 sil_set_mode wrap set_mode functions Synopsis int sil_set_mode struct ata_link * link struct ata_device ** r_failed Arguments link link to set up r_failed returned device when we fail Description Wrap the libata method for device setup as after the setup we need to inspect the results and do some configuration work LINUX Kernel Hackers Manual July 2017 sil_dev_config 9 4.1.27 sil_dev_config Apply device/host-specific errata fixups Synopsis void sil_dev_config struct ata_device * dev Arguments dev Device to be examined Description After the IDENTIFY [PACKET] DEVICE step is complete, and a device is known to be present, this function is called. We apply two errata fixups which are specific to Silicon Image, a Seagate and a Maxtor fixup. For certain Seagate devices, we must limit the maximum sectors to under 8K. For certain Maxtor devices, we must not program the drive beyond udma5. Both fixups are unfairly pessimistic. As soon as I get more information on these errata, I will create a more exhaustive list, and apply the fixups to only the specific devices/hosts/firmwares that need it. 20040111 - Seagate drives affected by the Mod15Write bug are blacklisted The Maxtor quirk is in the blacklist, but I'm keeping the original pessimistic fix for the following reasons... - There seems to be less info on it, only one device gleaned off the Windows driver, maybe only one is affected. More info would be greatly appreciated. - But then again UDMA5 is hardly anything to complain about Thanks The bulk of the ATA knowledge comes thanks to long conversations with Andre Hedrick (www.linux-ide.org), and long hours pondering the ATA and SCSI specifications. Thanks to Alan Cox for pointing out similarities between SATA and SCSI, and in general for motivation to hack on libata. libata's device detection method, ata_pio_devchk, and in general all the early probing was based on extensive study of Hale Landis's probe/reset code in his ATADRVR driver (www.ata-atapi.com).