David Fries

David@Fries.net

2013 This documentation is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License version 2. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. For more details see the file COPYING in the source distribution of Linux. W1 core functions. Kernel Hackers Manual July 2017 struct w1_reg_num 9 4.1.27 struct w1_reg_num broken out slave device id struct w1_reg_num { #if defined(__LITTLE_ENDIAN_BITFIELD) __u64 family:8; __u64 id:48; __u64 crc:8; #elif defined(__BIG_ENDIAN_BITFIELD) __u64 crc:8; __u64 id:48; __u64 family:8; #else #error "Please fix <asm/byteorder.h>" #endif }; family identifies the type of device id along with family is the unique device id crc checksum of the other bytes crc checksum of the other bytes id along with family is the unique device id family identifies the type of device Kernel Hackers Manual July 2017 struct w1_slave 9 4.1.27 struct w1_slave holds a single slave device on the bus struct w1_slave { struct module * owner; unsigned char name[W1_MAXNAMELEN]; struct list_head w1_slave_entry; struct w1_reg_num reg_num; atomic_t refcnt; int ttl; unsigned long flags; struct w1_master * master; struct w1_family * family; void * family_data; struct device dev; }; owner Points to the one wire wire kernel module. name[W1_MAXNAMELEN] Device id is ascii. w1_slave_entry data for the linked list reg_num the slave id in binary refcnt reference count, delete when 0 ttl decrement per search this slave isn't found, deatch at 0 flags bit flags for W1_SLAVE_ACTIVE W1_SLAVE_DETACH master bus which this slave is on family module for device family type family_data pointer for use by the family module dev kernel device identifier Kernel Hackers Manual July 2017 struct w1_bus_master 9 4.1.27 struct w1_bus_master operations available on a bus master struct w1_bus_master { void * data; u8 (* read_bit) (void *); void (* write_bit) (void *, u8); u8 (* touch_bit) (void *, u8); u8 (* read_byte) (void *); void (* write_byte) (void *, u8); u8 (* read_block) (void *, u8 *, int); void (* write_block) (void *, const u8 *, int); u8 (* triplet) (void *, u8); u8 (* reset_bus) (void *); u8 (* set_pullup) (void *, int); void (* search) (void *, struct w1_master *,u8, w1_slave_found_callback); }; data the first parameter in all the functions below read_bit Sample the line level return the level read (0 or 1) write_bit Sets the line level touch_bit the lowest-level function for devices that really support the 1-wire protocol. touch_bit(0) = write-0 cycle touch_bit(1) = write-1 / read cycle return the bit read (0 or 1) read_byte Reads a bytes. Same as 8 touch_bit(1) calls. return the byte read write_byte Writes a byte. Same as 8 touch_bit(x) calls. read_block Same as a series of read_byte calls return the number of bytes read write_block Same as a series of write_byte calls triplet Combines two reads and a smart write for ROM searches return bit0=Id bit1=comp_id bit2=dir_taken reset_bus long write-0 with a read for the presence pulse detection return -1=Error, 0=Device present, 1=No device present set_pullup Put out a strong pull-up pulse of the specified duration. return -1=Error, 0=completed search Really nice hardware can handles the different types of ROM search w1_master* is passed to the slave found callback. u8 is search_type, W1_SEARCH or W1_ALARM_SEARCH read_bit and write_bit are very low level functions and should only be used with hardware that doesn't really support 1-wire operations, like a parallel/serial port. Either define read_bit and write_bit OR define, at minimum, touch_bit and reset_bus. Kernel Hackers Manual July 2017 enum w1_master_flags 9 4.1.27 enum w1_master_flags bitfields used in w1_master.flags enum w1_master_flags { W1_ABORT_SEARCH, W1_WARN_MAX_COUNT }; W1_ABORT_SEARCH abort searching early on shutdown W1_WARN_MAX_COUNT limit warning when the maximum count is reached Kernel Hackers Manual July 2017 struct w1_master 9 4.1.27 struct w1_master one per bus master struct w1_master { struct list_head w1_master_entry; struct module * owner; unsigned char name[W1_MAXNAMELEN]; struct mutex list_mutex; struct list_head slist; struct list_head async_list; int max_slave_count; int slave_count; unsigned long attempts; int slave_ttl; int initialized; u32 id; int search_count; u64 search_id; atomic_t refcnt; void * priv; int enable_pullup; int pullup_duration; long flags; struct task_struct * thread; struct mutex mutex; struct mutex bus_mutex; struct device_driver * driver; struct device dev; struct w1_bus_master * bus_master; u32 seq; }; w1_master_entry master linked list owner module owner name[W1_MAXNAMELEN] dynamically allocate bus name list_mutex protect slist and async_list slist linked list of slaves async_list linked list of netlink commands to execute max_slave_count maximum number of slaves to search for at a time slave_count current number of slaves known attempts number of searches ran slave_ttl number of searches before a slave is timed out initialized prevent init/removal race conditions id w1 bus number search_count number of automatic searches to run, -1 unlimited search_id allows continuing a search refcnt reference count priv private data storage enable_pullup allows a strong pullup pullup_duration time for the next strong pullup flags one of w1_master_flags thread thread for bus search and netlink commands mutex protect most of w1_master bus_mutex pretect concurrent bus access driver sysfs driver dev sysfs device bus_master io operations available seq sequence number used for netlink broadcasts Kernel Hackers Manual July 2017 struct w1_async_cmd 9 4.1.27 struct w1_async_cmd execute callback from the w1_process kthread struct w1_async_cmd { struct list_head async_entry; void (* cb) (struct w1_master *dev, struct w1_async_cmd *async_cmd); }; async_entry link entry cb callback function, must list_del and destroy this list before returning When inserted into the w1_master async_list, w1_process will execute the callback. Embed this into the structure with the command details. W1 core functions. Kernel Hackers Manual July 2017 w1_search 9 4.1.27 w1_search Performs a ROM Search & registers any devices found. void w1_search struct w1_master * dev u8 search_type w1_slave_found_callback cb dev The master device to search search_type W1_SEARCH to search all devices, or W1_ALARM_SEARCH to return only devices in the alarmed state cb Function to call when a device is found The 1-wire search is a simple binary tree search. For each bit of the address, we read two bits and write one bit. The bit written will put to sleep all devies that don't match that bit. When the two reads differ, the direction choice is obvious. When both bits are 0, we must choose a path to take. When we can scan all 64 bits without having to choose a path, we are done. See Application note 187 1-wire search algorithm at www.maxim-ic.com Kernel Hackers Manual July 2017 w1_process_callbacks 9 4.1.27 w1_process_callbacks execute each dev->async_list callback entry int w1_process_callbacks struct w1_master * dev dev w1_master device The w1 master list_mutex must be held. 1 if there were commands to executed 0 otherwise Allows registering device family operations. Kernel Hackers Manual July 2017 struct w1_family_ops 9 4.1.27 struct w1_family_ops operations for a family type struct w1_family_ops { int (* add_slave) (struct w1_slave *); void (* remove_slave) (struct w1_slave *); const struct attribute_group ** groups; }; add_slave add_slave remove_slave remove_slave groups sysfs group Kernel Hackers Manual July 2017 struct w1_family 9 4.1.27 struct w1_family reference counted family structure. struct w1_family { struct list_head family_entry; u8 fid; struct w1_family_ops * fops; atomic_t refcnt; }; family_entry family linked list fid 8 bit family identifier fops operations for this family refcnt reference counter Allows registering device family operations. Kernel Hackers Manual July 2017 w1_register_family 9 4.1.27 w1_register_family register a device family driver int w1_register_family struct w1_family * newf newf family to register Kernel Hackers Manual July 2017 w1_unregister_family 9 4.1.27 w1_unregister_family unregister a device family driver void w1_unregister_family struct w1_family * fent fent family to unregister W1 internal initialization for master devices. Kernel Hackers Manual July 2017 w1_add_master_device 9 4.1.27 w1_add_master_device registers a new master device int w1_add_master_device struct w1_bus_master * master master master bus device to register Kernel Hackers Manual July 2017 w1_remove_master_device 9 4.1.27 w1_remove_master_device unregister a master device void w1_remove_master_device struct w1_bus_master * bm bm master bus device to remove W1 external netlink API structures and commands. Kernel Hackers Manual July 2017 enum w1_cn_msg_flags 9 4.1.27 enum w1_cn_msg_flags bitfield flags for struct cn_msg.flags enum w1_cn_msg_flags { W1_CN_BUNDLE }; W1_CN_BUNDLE Request bundling replies into fewer messagse. Be prepared to handle multiple struct cn_msg, struct w1_netlink_msg, and struct w1_netlink_cmd in one packet. Kernel Hackers Manual July 2017 enum w1_netlink_message_types 9 4.1.27 enum w1_netlink_message_types message type enum w1_netlink_message_types { W1_SLAVE_ADD, W1_SLAVE_REMOVE, W1_MASTER_ADD, W1_MASTER_REMOVE, W1_MASTER_CMD, W1_SLAVE_CMD, W1_LIST_MASTERS }; W1_SLAVE_ADD notification that a slave device was added W1_SLAVE_REMOVE notification that a slave device was removed W1_MASTER_ADD notification that a new bus master was added W1_MASTER_REMOVE notification that a bus masterwas removed W1_MASTER_CMD initiate operations on a specific master W1_SLAVE_CMD sends reset, selects the slave, then does a read/write/touch operation W1_LIST_MASTERS used to determine the bus master identifiers Kernel Hackers Manual July 2017 struct w1_netlink_msg 9 4.1.27 struct w1_netlink_msg holds w1 message type, id, and result struct w1_netlink_msg { __u8 type; __u8 status; __u16 len; union id; __u8 data[0]; }; type one of enum w1_netlink_message_types status kernel feedback for success 0 or errno failure value len length of data following w1_netlink_msg id union holding master bus id (msg.id) and slave device id (id[8]). data[0] start address of any following data The base message structure for w1 messages over netlink. The netlink connector data sequence is, struct nlmsghdr, struct cn_msg, then one or more struct w1_netlink_msg (each with optional data). Kernel Hackers Manual July 2017 enum w1_commands 9 4.1.27 enum w1_commands commands available for master or slave operations enum w1_commands { W1_CMD_READ, W1_CMD_WRITE, W1_CMD_SEARCH, W1_CMD_ALARM_SEARCH, W1_CMD_TOUCH, W1_CMD_RESET, W1_CMD_SLAVE_ADD, W1_CMD_SLAVE_REMOVE, W1_CMD_LIST_SLAVES, W1_CMD_MAX }; W1_CMD_READ read len bytes W1_CMD_WRITE write len bytes W1_CMD_SEARCH initiate a standard search, returns only the slave devices found during that search W1_CMD_ALARM_SEARCH search for devices that are currently alarming W1_CMD_TOUCH Touches a series of bytes. W1_CMD_RESET sends a bus reset on the given master W1_CMD_SLAVE_ADD adds a slave to the given master, 8 byte slave id at data[0] W1_CMD_SLAVE_REMOVE removes a slave to the given master, 8 byte slave id at data[0] W1_CMD_LIST_SLAVES list of slaves registered on this master W1_CMD_MAX number of available commands Kernel Hackers Manual July 2017 struct w1_netlink_cmd 9 4.1.27 struct w1_netlink_cmd holds the command and data struct w1_netlink_cmd { __u8 cmd; __u8 res; __u16 len; __u8 data[0]; }; cmd one of enum w1_commands res reserved len length of data following w1_netlink_cmd data[0] start address of any following data One or more struct w1_netlink_cmd is placed starting at w1_netlink_msg.data each with optional data. W1 input/output. Kernel Hackers Manual July 2017 w1_write_8 9 4.1.27 w1_write_8 Writes 8 bits. void w1_write_8 struct w1_master * dev u8 byte dev the master device byte the byte to write Kernel Hackers Manual July 2017 w1_read_8 9 4.1.27 w1_read_8 Reads 8 bits. u8 w1_read_8 struct w1_master * dev dev the master device the byte read Kernel Hackers Manual July 2017 w1_write_block 9 4.1.27 w1_write_block Writes a series of bytes. void w1_write_block struct w1_master * dev const u8 * buf int len dev the master device buf pointer to the data to write len the number of bytes to write Kernel Hackers Manual July 2017 w1_touch_block 9 4.1.27 w1_touch_block Touches a series of bytes. void w1_touch_block struct w1_master * dev u8 * buf int len dev the master device buf pointer to the data to write len the number of bytes to write Kernel Hackers Manual July 2017 w1_read_block 9 4.1.27 w1_read_block Reads a series of bytes. u8 w1_read_block struct w1_master * dev u8 * buf int len dev the master device buf pointer to the buffer to fill len the number of bytes to read the number of bytes read Kernel Hackers Manual July 2017 w1_reset_bus 9 4.1.27 w1_reset_bus Issues a reset bus sequence. int w1_reset_bus struct w1_master * dev dev the master device 0=Device present, 1=No device present or error Kernel Hackers Manual July 2017 w1_reset_select_slave 9 4.1.27 w1_reset_select_slave reset and select a slave int w1_reset_select_slave struct w1_slave * sl sl the slave to select Resets the bus and then selects the slave by sending either a skip rom or a rom match. A skip rom is issued if there is only one device registered on the bus. The w1 master lock must be held. 0=success, anything else=error Kernel Hackers Manual July 2017 w1_reset_resume_command 9 4.1.27 w1_reset_resume_command resume instead of another match ROM int w1_reset_resume_command struct w1_master * dev dev the master device When the workflow with a slave amongst many requires several successive commands a reset between each, this function is similar to doing a reset then a match ROM for the last matched ROM. The advantage being that the matched ROM step is skipped in favor of the resume command. The slave must support the command of course. If the bus has only one slave, traditionnaly the match ROM is skipped and a SKIP ROM is done for efficiency. On multi-slave busses, this doesn't work of course, but the resume command is the next best thing. The w1 master lock must be held. Kernel Hackers Manual July 2017 w1_next_pullup 9 4.1.27 w1_next_pullup register for a strong pullup void w1_next_pullup struct w1_master * dev int delay dev the master device delay time in milliseconds Put out a strong pull-up of the specified duration after the next write operation. Not all hardware supports strong pullups. Hardware that doesn't support strong pullups will sleep for the given time after the write operation without a strong pullup. This is a one shot request for the next write, specifying zero will clear a previous request. The w1 master lock must be held. 0=success, anything else=error Kernel Hackers Manual July 2017 w1_touch_bit 9 4.1.27 w1_touch_bit Generates a write-0 or write-1 cycle and samples the level. u8 w1_touch_bit struct w1_master * dev int bit dev the master device bit 0 - write a 0, 1 - write a 0 read the level Kernel Hackers Manual July 2017 w1_write_bit 9 4.1.27 w1_write_bit Generates a write-0 or write-1 cycle. void w1_write_bit struct w1_master * dev int bit dev the master device bit bit to write Only call if dev->bus_master->touch_bit is NULL Kernel Hackers Manual July 2017 w1_pre_write 9 4.1.27 w1_pre_write pre-write operations void w1_pre_write struct w1_master * dev dev the master device Pre-write operation, currently only supporting strong pullups. Program the hardware for a strong pullup, if one has been requested and the hardware supports it. Kernel Hackers Manual July 2017 w1_post_write 9 4.1.27 w1_post_write post-write options void w1_post_write struct w1_master * dev dev the master device Post-write operation, currently only supporting strong pullups. If a strong pullup was requested, clear it if the hardware supports them, or execute the delay otherwise, in either case clear the request. Kernel Hackers Manual July 2017 w1_read_bit 9 4.1.27 w1_read_bit Generates a write-1 cycle and samples the level. u8 w1_read_bit struct w1_master * dev dev the master device Only call if dev->bus_master->touch_bit is NULL Kernel Hackers Manual July 2017 w1_triplet 9 4.1.27 w1_triplet * Does a triplet - used for searching ROM addresses. u8 w1_triplet struct w1_master * dev int bdir dev the master device bdir the bit to write if both id_bit and comp_bit are 0 bit 0 = id_bit bit 1 = comp_bit bit 2 = dir_taken If both bits 0 & 1 are set, the search should be restarted. bit fields - see above