drivers/tty/hvc/hvcs.c

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This source file includes following definitions.
from_vio_dev
hvcs_partner_vtys_show
hvcs_partner_clcs_show
hvcs_current_vty_store
hvcs_current_vty_show
hvcs_vterm_state_store
hvcs_vterm_state_show
hvcs_index_show
rescan_show
rescan_store
hvcs_kick
hvcs_unthrottle
hvcs_throttle
hvcs_handle_interrupt
hvcs_try_write
hvcs_io
khvcsd
hvcs_return_index
hvcs_destruct_port
hvcs_get_index
hvcs_probe
hvcs_remove
hvcs_set_pi
hvcs_get_pi
hvcs_rescan_devices_list
hvcs_has_pi
hvcs_partner_connect
hvcs_partner_free
hvcs_enable_device
hvcs_get_by_index
hvcs_install
hvcs_open
hvcs_close
hvcs_cleanup
hvcs_hangup
hvcs_write
hvcs_write_room
hvcs_chars_in_buffer
hvcs_alloc_index_list
hvcs_free_index_list
hvcs_initialize
hvcs_module_init
hvcs_module_exit
   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * IBM eServer Hypervisor Virtual Console Server Device Driver
   4  * Copyright (C) 2003, 2004 IBM Corp.
   5  *  Ryan S. Arnold (rsa@us.ibm.com)
   6  *
   7  * Author(s) :  Ryan S. Arnold <rsa@us.ibm.com>
   8  *
   9  * This is the device driver for the IBM Hypervisor Virtual Console Server,
  10  * "hvcs".  The IBM hvcs provides a tty driver interface to allow Linux
  11  * user space applications access to the system consoles of logically
  12  * partitioned operating systems, e.g. Linux, running on the same partitioned
  13  * Power5 ppc64 system.  Physical hardware consoles per partition are not
  14  * practical on this hardware so system consoles are accessed by this driver
  15  * using inter-partition firmware interfaces to virtual terminal devices.
  16  *
  17  * A vty is known to the HMC as a "virtual serial server adapter".  It is a
  18  * virtual terminal device that is created by firmware upon partition creation
  19  * to act as a partitioned OS's console device.
  20  *
  21  * Firmware dynamically (via hotplug) exposes vty-servers to a running ppc64
  22  * Linux system upon their creation by the HMC or their exposure during boot.
  23  * The non-user interactive backend of this driver is implemented as a vio
  24  * device driver so that it can receive notification of vty-server lifetimes
  25  * after it registers with the vio bus to handle vty-server probe and remove
  26  * callbacks.
  27  *
  28  * Many vty-servers can be configured to connect to one vty, but a vty can
  29  * only be actively connected to by a single vty-server, in any manner, at one
  30  * time.  If the HMC is currently hosting the console for a target Linux
  31  * partition; attempts to open the tty device to the partition's console using
  32  * the hvcs on any partition will return -EBUSY with every open attempt until
  33  * the HMC frees the connection between its vty-server and the desired
  34  * partition's vty device.  Conversely, a vty-server may only be connected to
  35  * a single vty at one time even though it may have several configured vty
  36  * partner possibilities.
  37  *
  38  * Firmware does not provide notification of vty partner changes to this
  39  * driver.  This means that an HMC Super Admin may add or remove partner vtys
  40  * from a vty-server's partner list but the changes will not be signaled to
  41  * the vty-server.  Firmware only notifies the driver when a vty-server is
  42  * added or removed from the system.  To compensate for this deficiency, this
  43  * driver implements a sysfs update attribute which provides a method for
  44  * rescanning partner information upon a user's request.
  45  *
  46  * Each vty-server, prior to being exposed to this driver is reference counted
  47  * using the 2.6 Linux kernel kref construct.
  48  *
  49  * For direction on installation and usage of this driver please reference
  50  * Documentation/powerpc/hvcs.rst.
  51  */
  52 
  53 #include <linux/device.h>
  54 #include <linux/init.h>
  55 #include <linux/interrupt.h>
  56 #include <linux/kernel.h>
  57 #include <linux/kref.h>
  58 #include <linux/kthread.h>
  59 #include <linux/list.h>
  60 #include <linux/major.h>
  61 #include <linux/module.h>
  62 #include <linux/moduleparam.h>
  63 #include <linux/sched.h>
  64 #include <linux/slab.h>
  65 #include <linux/spinlock.h>
  66 #include <linux/stat.h>
  67 #include <linux/tty.h>
  68 #include <linux/tty_flip.h>
  69 #include <asm/hvconsole.h>
  70 #include <asm/hvcserver.h>
  71 #include <linux/uaccess.h>
  72 #include <asm/vio.h>
  73 
  74 /*
  75  * 1.3.0 -> 1.3.1 In hvcs_open memset(..,0x00,..) instead of memset(..,0x3F,00).
  76  * Removed braces around single statements following conditionals.  Removed '=
  77  * 0' after static int declarations since these default to zero.  Removed
  78  * list_for_each_safe() and replaced with list_for_each_entry() in
  79  * hvcs_get_by_index().  The 'safe' version is un-needed now that the driver is
  80  * using spinlocks.  Changed spin_lock_irqsave() to spin_lock() when locking
  81  * hvcs_structs_lock and hvcs_pi_lock since these are not touched in an int
  82  * handler.  Initialized hvcs_structs_lock and hvcs_pi_lock to
  83  * SPIN_LOCK_UNLOCKED at declaration time rather than in hvcs_module_init().
  84  * Added spin_lock around list_del() in destroy_hvcs_struct() to protect the
  85  * list traversals from a deletion.  Removed '= NULL' from pointer declaration
  86  * statements since they are initialized NULL by default.  Removed wmb()
  87  * instances from hvcs_try_write().  They probably aren't needed with locking in
  88  * place.  Added check and cleanup for hvcs_pi_buff = kmalloc() in
  89  * hvcs_module_init().  Exposed hvcs_struct.index via a sysfs attribute so that
  90  * the coupling between /dev/hvcs* and a vty-server can be automatically
  91  * determined.  Moved kobject_put() in hvcs_open outside of the
  92  * spin_unlock_irqrestore().
  93  *
  94  * 1.3.1 -> 1.3.2 Changed method for determining hvcs_struct->index and had it
  95  * align with how the tty layer always assigns the lowest index available.  This
  96  * change resulted in a list of ints that denotes which indexes are available.
  97  * Device additions and removals use the new hvcs_get_index() and
  98  * hvcs_return_index() helper functions.  The list is created with
  99  * hvsc_alloc_index_list() and it is destroyed with hvcs_free_index_list().
 100  * Without these fixes hotplug vty-server adapter support goes crazy with this
 101  * driver if the user removes a vty-server adapter.  Moved free_irq() outside of
 102  * the hvcs_final_close() function in order to get it out of the spinlock.
 103  * Rearranged hvcs_close().  Cleaned up some printks and did some housekeeping
 104  * on the changelog.  Removed local CLC_LENGTH and used HVCS_CLC_LENGTH from
 105  * arch/powerepc/include/asm/hvcserver.h
 106  *
 107  * 1.3.2 -> 1.3.3 Replaced yield() in hvcs_close() with tty_wait_until_sent() to
 108  * prevent possible lockup with realtime scheduling as similarly pointed out by
 109  * akpm in hvc_console.  Changed resulted in the removal of hvcs_final_close()
 110  * to reorder cleanup operations and prevent discarding of pending data during
 111  * an hvcs_close().  Removed spinlock protection of hvcs_struct data members in
 112  * hvcs_write_room() and hvcs_chars_in_buffer() because they aren't needed.
 113  */
 114 
 115 #define HVCS_DRIVER_VERSION "1.3.3"
 116 
 117 MODULE_AUTHOR("Ryan S. Arnold <rsa@us.ibm.com>");
 118 MODULE_DESCRIPTION("IBM hvcs (Hypervisor Virtual Console Server) Driver");
 119 MODULE_LICENSE("GPL");
 120 MODULE_VERSION(HVCS_DRIVER_VERSION);
 121 
 122 /*
 123  * Wait this long per iteration while trying to push buffered data to the
 124  * hypervisor before allowing the tty to complete a close operation.
 125  */
 126 #define HVCS_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
 127 
 128 /*
 129  * Since the Linux TTY code does not currently (2-04-2004) support dynamic
 130  * addition of tty derived devices and we shouldn't allocate thousands of
 131  * tty_device pointers when the number of vty-server & vty partner connections
 132  * will most often be much lower than this, we'll arbitrarily allocate
 133  * HVCS_DEFAULT_SERVER_ADAPTERS tty_structs and cdev's by default when we
 134  * register the tty_driver. This can be overridden using an insmod parameter.
 135  */
 136 #define HVCS_DEFAULT_SERVER_ADAPTERS    64
 137 
 138 /*
 139  * The user can't insmod with more than HVCS_MAX_SERVER_ADAPTERS hvcs device
 140  * nodes as a sanity check.  Theoretically there can be over 1 Billion
 141  * vty-server & vty partner connections.
 142  */
 143 #define HVCS_MAX_SERVER_ADAPTERS        1024
 144 
 145 /*
 146  * We let Linux assign us a major number and we start the minors at zero.  There
 147  * is no intuitive mapping between minor number and the target vty-server
 148  * adapter except that each new vty-server adapter is always assigned to the
 149  * smallest minor number available.
 150  */
 151 #define HVCS_MINOR_START        0
 152 
 153 /*
 154  * The hcall interface involves putting 8 chars into each of two registers.
 155  * We load up those 2 registers (in arch/powerpc/platforms/pseries/hvconsole.c)
 156  * by casting char[16] to long[2].  It would work without __ALIGNED__, but a 
 157  * little (tiny) bit slower because an unaligned load is slower than aligned 
 158  * load.
 159  */
 160 #define __ALIGNED__     __attribute__((__aligned__(8)))
 161 
 162 /*
 163  * How much data can firmware send with each hvc_put_chars()?  Maybe this
 164  * should be moved into an architecture specific area.
 165  */
 166 #define HVCS_BUFF_LEN   16
 167 
 168 /*
 169  * This is the maximum amount of data we'll let the user send us (hvcs_write) at
 170  * once in a chunk as a sanity check.
 171  */
 172 #define HVCS_MAX_FROM_USER      4096
 173 
 174 /*
 175  * Be careful when adding flags to this line discipline.  Don't add anything
 176  * that will cause echoing or we'll go into recursive loop echoing chars back
 177  * and forth with the console drivers.
 178  */
 179 static const struct ktermios hvcs_tty_termios = {
 180         .c_iflag = IGNBRK | IGNPAR,
 181         .c_oflag = OPOST,
 182         .c_cflag = B38400 | CS8 | CREAD | HUPCL,
 183         .c_cc = INIT_C_CC,
 184         .c_ispeed = 38400,
 185         .c_ospeed = 38400
 186 };
 187 
 188 /*
 189  * This value is used to take the place of a command line parameter when the
 190  * module is inserted.  It starts as -1 and stays as such if the user doesn't
 191  * specify a module insmod parameter.  If they DO specify one then it is set to
 192  * the value of the integer passed in.
 193  */
 194 static int hvcs_parm_num_devs = -1;
 195 module_param(hvcs_parm_num_devs, int, 0);
 196 
 197 static const char hvcs_driver_name[] = "hvcs";
 198 static const char hvcs_device_node[] = "hvcs";
 199 static const char hvcs_driver_string[]
 200         = "IBM hvcs (Hypervisor Virtual Console Server) Driver";
 201 
 202 /* Status of partner info rescan triggered via sysfs. */
 203 static int hvcs_rescan_status;
 204 
 205 static struct tty_driver *hvcs_tty_driver;
 206 
 207 /*
 208  * In order to be somewhat sane this driver always associates the hvcs_struct
 209  * index element with the numerically equal tty->index.  This means that a
 210  * hotplugged vty-server adapter will always map to the lowest index valued
 211  * device node.  If vty-servers were hotplug removed from the system and then
 212  * new ones added the new vty-server may have the largest slot number of all
 213  * the vty-server adapters in the partition but it may have the lowest dev node
 214  * index of all the adapters due to the hole left by the hotplug removed
 215  * adapter.  There are a set of functions provided to get the lowest index for
 216  * a new device as well as return the index to the list.  This list is allocated
 217  * with a number of elements equal to the number of device nodes requested when
 218  * the module was inserted.
 219  */
 220 static int *hvcs_index_list;
 221 
 222 /*
 223  * How large is the list?  This is kept for traversal since the list is
 224  * dynamically created.
 225  */
 226 static int hvcs_index_count;
 227 
 228 /*
 229  * Used by the khvcsd to pick up I/O operations when the kernel_thread is
 230  * already awake but potentially shifted to TASK_INTERRUPTIBLE state.
 231  */
 232 static int hvcs_kicked;
 233 
 234 /*
 235  * Use by the kthread construct for task operations like waking the sleeping
 236  * thread and stopping the kthread.
 237  */
 238 static struct task_struct *hvcs_task;
 239 
 240 /*
 241  * We allocate this for the use of all of the hvcs_structs when they fetch
 242  * partner info.
 243  */
 244 static unsigned long *hvcs_pi_buff;
 245 
 246 /* Only allow one hvcs_struct to use the hvcs_pi_buff at a time. */
 247 static DEFINE_SPINLOCK(hvcs_pi_lock);
 248 
 249 /* One vty-server per hvcs_struct */
 250 struct hvcs_struct {
 251         struct tty_port port;
 252         spinlock_t lock;
 253 
 254         /*
 255          * This index identifies this hvcs device as the complement to a
 256          * specific tty index.
 257          */
 258         unsigned int index;
 259 
 260         /*
 261          * Used to tell the driver kernel_thread what operations need to take
 262          * place upon this hvcs_struct instance.
 263          */
 264         int todo_mask;
 265 
 266         /*
 267          * This buffer is required so that when hvcs_write_room() reports that
 268          * it can send HVCS_BUFF_LEN characters that it will buffer the full
 269          * HVCS_BUFF_LEN characters if need be.  This is essential for opost
 270          * writes since they do not do high level buffering and expect to be
 271          * able to send what the driver commits to sending buffering
 272          * [e.g. tab to space conversions in n_tty.c opost()].
 273          */
 274         char buffer[HVCS_BUFF_LEN];
 275         int chars_in_buffer;
 276 
 277         /*
 278          * Any variable below is valid before a tty is connected and
 279          * stays valid after the tty is disconnected.  These shouldn't be
 280          * whacked until the kobject refcount reaches zero though some entries
 281          * may be changed via sysfs initiatives.
 282          */
 283         int connected; /* is the vty-server currently connected to a vty? */
 284         uint32_t p_unit_address; /* partner unit address */
 285         uint32_t p_partition_ID; /* partner partition ID */
 286         char p_location_code[HVCS_CLC_LENGTH + 1]; /* CLC + Null Term */
 287         struct list_head next; /* list management */
 288         struct vio_dev *vdev;
 289 };
 290 
 291 static LIST_HEAD(hvcs_structs);
 292 static DEFINE_SPINLOCK(hvcs_structs_lock);
 293 static DEFINE_MUTEX(hvcs_init_mutex);
 294 
 295 static void hvcs_unthrottle(struct tty_struct *tty);
 296 static void hvcs_throttle(struct tty_struct *tty);
 297 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance);
 298 
 299 static int hvcs_write(struct tty_struct *tty,
 300                 const unsigned char *buf, int count);
 301 static int hvcs_write_room(struct tty_struct *tty);
 302 static int hvcs_chars_in_buffer(struct tty_struct *tty);
 303 
 304 static int hvcs_has_pi(struct hvcs_struct *hvcsd);
 305 static void hvcs_set_pi(struct hvcs_partner_info *pi,
 306                 struct hvcs_struct *hvcsd);
 307 static int hvcs_get_pi(struct hvcs_struct *hvcsd);
 308 static int hvcs_rescan_devices_list(void);
 309 
 310 static int hvcs_partner_connect(struct hvcs_struct *hvcsd);
 311 static void hvcs_partner_free(struct hvcs_struct *hvcsd);
 312 
 313 static int hvcs_enable_device(struct hvcs_struct *hvcsd,
 314                 uint32_t unit_address, unsigned int irq, struct vio_dev *dev);
 315 
 316 static int hvcs_open(struct tty_struct *tty, struct file *filp);
 317 static void hvcs_close(struct tty_struct *tty, struct file *filp);
 318 static void hvcs_hangup(struct tty_struct * tty);
 319 
 320 static int hvcs_probe(struct vio_dev *dev,
 321                 const struct vio_device_id *id);
 322 static int hvcs_remove(struct vio_dev *dev);
 323 static int __init hvcs_module_init(void);
 324 static void __exit hvcs_module_exit(void);
 325 static int hvcs_initialize(void);
 326 
 327 #define HVCS_SCHED_READ 0x00000001
 328 #define HVCS_QUICK_READ 0x00000002
 329 #define HVCS_TRY_WRITE  0x00000004
 330 #define HVCS_READ_MASK  (HVCS_SCHED_READ | HVCS_QUICK_READ)
 331 
 332 static inline struct hvcs_struct *from_vio_dev(struct vio_dev *viod)
 333 {
 334         return dev_get_drvdata(&viod->dev);
 335 }
 336 /* The sysfs interface for the driver and devices */
 337 
 338 static ssize_t hvcs_partner_vtys_show(struct device *dev, struct device_attribute *attr, char *buf)
 339 {
 340         struct vio_dev *viod = to_vio_dev(dev);
 341         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 342         unsigned long flags;
 343         int retval;
 344 
 345         spin_lock_irqsave(&hvcsd->lock, flags);
 346         retval = sprintf(buf, "%X\n", hvcsd->p_unit_address);
 347         spin_unlock_irqrestore(&hvcsd->lock, flags);
 348         return retval;
 349 }
 350 static DEVICE_ATTR(partner_vtys, S_IRUGO, hvcs_partner_vtys_show, NULL);
 351 
 352 static ssize_t hvcs_partner_clcs_show(struct device *dev, struct device_attribute *attr, char *buf)
 353 {
 354         struct vio_dev *viod = to_vio_dev(dev);
 355         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 356         unsigned long flags;
 357         int retval;
 358 
 359         spin_lock_irqsave(&hvcsd->lock, flags);
 360         retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 361         spin_unlock_irqrestore(&hvcsd->lock, flags);
 362         return retval;
 363 }
 364 static DEVICE_ATTR(partner_clcs, S_IRUGO, hvcs_partner_clcs_show, NULL);
 365 
 366 static ssize_t hvcs_current_vty_store(struct device *dev, struct device_attribute *attr, const char * buf,
 367                 size_t count)
 368 {
 369         /*
 370          * Don't need this feature at the present time because firmware doesn't
 371          * yet support multiple partners.
 372          */
 373         printk(KERN_INFO "HVCS: Denied current_vty change: -EPERM.\n");
 374         return -EPERM;
 375 }
 376 
 377 static ssize_t hvcs_current_vty_show(struct device *dev, struct device_attribute *attr, char *buf)
 378 {
 379         struct vio_dev *viod = to_vio_dev(dev);
 380         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 381         unsigned long flags;
 382         int retval;
 383 
 384         spin_lock_irqsave(&hvcsd->lock, flags);
 385         retval = sprintf(buf, "%s\n", &hvcsd->p_location_code[0]);
 386         spin_unlock_irqrestore(&hvcsd->lock, flags);
 387         return retval;
 388 }
 389 
 390 static DEVICE_ATTR(current_vty,
 391         S_IRUGO | S_IWUSR, hvcs_current_vty_show, hvcs_current_vty_store);
 392 
 393 static ssize_t hvcs_vterm_state_store(struct device *dev, struct device_attribute *attr, const char *buf,
 394                 size_t count)
 395 {
 396         struct vio_dev *viod = to_vio_dev(dev);
 397         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 398         unsigned long flags;
 399 
 400         /* writing a '0' to this sysfs entry will result in the disconnect. */
 401         if (simple_strtol(buf, NULL, 0) != 0)
 402                 return -EINVAL;
 403 
 404         spin_lock_irqsave(&hvcsd->lock, flags);
 405 
 406         if (hvcsd->port.count > 0) {
 407                 spin_unlock_irqrestore(&hvcsd->lock, flags);
 408                 printk(KERN_INFO "HVCS: vterm state unchanged.  "
 409                                 "The hvcs device node is still in use.\n");
 410                 return -EPERM;
 411         }
 412 
 413         if (hvcsd->connected == 0) {
 414                 spin_unlock_irqrestore(&hvcsd->lock, flags);
 415                 printk(KERN_INFO "HVCS: vterm state unchanged. The"
 416                                 " vty-server is not connected to a vty.\n");
 417                 return -EPERM;
 418         }
 419 
 420         hvcs_partner_free(hvcsd);
 421         printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 422                         " partner vty@%X:%d connection.\n",
 423                         hvcsd->vdev->unit_address,
 424                         hvcsd->p_unit_address,
 425                         (uint32_t)hvcsd->p_partition_ID);
 426 
 427         spin_unlock_irqrestore(&hvcsd->lock, flags);
 428         return count;
 429 }
 430 
 431 static ssize_t hvcs_vterm_state_show(struct device *dev, struct device_attribute *attr, char *buf)
 432 {
 433         struct vio_dev *viod = to_vio_dev(dev);
 434         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 435         unsigned long flags;
 436         int retval;
 437 
 438         spin_lock_irqsave(&hvcsd->lock, flags);
 439         retval = sprintf(buf, "%d\n", hvcsd->connected);
 440         spin_unlock_irqrestore(&hvcsd->lock, flags);
 441         return retval;
 442 }
 443 static DEVICE_ATTR(vterm_state, S_IRUGO | S_IWUSR,
 444                 hvcs_vterm_state_show, hvcs_vterm_state_store);
 445 
 446 static ssize_t hvcs_index_show(struct device *dev, struct device_attribute *attr, char *buf)
 447 {
 448         struct vio_dev *viod = to_vio_dev(dev);
 449         struct hvcs_struct *hvcsd = from_vio_dev(viod);
 450         unsigned long flags;
 451         int retval;
 452 
 453         spin_lock_irqsave(&hvcsd->lock, flags);
 454         retval = sprintf(buf, "%d\n", hvcsd->index);
 455         spin_unlock_irqrestore(&hvcsd->lock, flags);
 456         return retval;
 457 }
 458 
 459 static DEVICE_ATTR(index, S_IRUGO, hvcs_index_show, NULL);
 460 
 461 static struct attribute *hvcs_attrs[] = {
 462         &dev_attr_partner_vtys.attr,
 463         &dev_attr_partner_clcs.attr,
 464         &dev_attr_current_vty.attr,
 465         &dev_attr_vterm_state.attr,
 466         &dev_attr_index.attr,
 467         NULL,
 468 };
 469 
 470 static struct attribute_group hvcs_attr_group = {
 471         .attrs = hvcs_attrs,
 472 };
 473 
 474 static ssize_t rescan_show(struct device_driver *ddp, char *buf)
 475 {
 476         /* A 1 means it is updating, a 0 means it is done updating */
 477         return snprintf(buf, PAGE_SIZE, "%d\n", hvcs_rescan_status);
 478 }
 479 
 480 static ssize_t rescan_store(struct device_driver *ddp, const char * buf,
 481                 size_t count)
 482 {
 483         if ((simple_strtol(buf, NULL, 0) != 1)
 484                 && (hvcs_rescan_status != 0))
 485                 return -EINVAL;
 486 
 487         hvcs_rescan_status = 1;
 488         printk(KERN_INFO "HVCS: rescanning partner info for all"
 489                 " vty-servers.\n");
 490         hvcs_rescan_devices_list();
 491         hvcs_rescan_status = 0;
 492         return count;
 493 }
 494 
 495 static DRIVER_ATTR_RW(rescan);
 496 
 497 static void hvcs_kick(void)
 498 {
 499         hvcs_kicked = 1;
 500         wmb();
 501         wake_up_process(hvcs_task);
 502 }
 503 
 504 static void hvcs_unthrottle(struct tty_struct *tty)
 505 {
 506         struct hvcs_struct *hvcsd = tty->driver_data;
 507         unsigned long flags;
 508 
 509         spin_lock_irqsave(&hvcsd->lock, flags);
 510         hvcsd->todo_mask |= HVCS_SCHED_READ;
 511         spin_unlock_irqrestore(&hvcsd->lock, flags);
 512         hvcs_kick();
 513 }
 514 
 515 static void hvcs_throttle(struct tty_struct *tty)
 516 {
 517         struct hvcs_struct *hvcsd = tty->driver_data;
 518         unsigned long flags;
 519 
 520         spin_lock_irqsave(&hvcsd->lock, flags);
 521         vio_disable_interrupts(hvcsd->vdev);
 522         spin_unlock_irqrestore(&hvcsd->lock, flags);
 523 }
 524 
 525 /*
 526  * If the device is being removed we don't have to worry about this interrupt
 527  * handler taking any further interrupts because they are disabled which means
 528  * the hvcs_struct will always be valid in this handler.
 529  */
 530 static irqreturn_t hvcs_handle_interrupt(int irq, void *dev_instance)
 531 {
 532         struct hvcs_struct *hvcsd = dev_instance;
 533 
 534         spin_lock(&hvcsd->lock);
 535         vio_disable_interrupts(hvcsd->vdev);
 536         hvcsd->todo_mask |= HVCS_SCHED_READ;
 537         spin_unlock(&hvcsd->lock);
 538         hvcs_kick();
 539 
 540         return IRQ_HANDLED;
 541 }
 542 
 543 /* This function must be called with the hvcsd->lock held */
 544 static void hvcs_try_write(struct hvcs_struct *hvcsd)
 545 {
 546         uint32_t unit_address = hvcsd->vdev->unit_address;
 547         struct tty_struct *tty = hvcsd->port.tty;
 548         int sent;
 549 
 550         if (hvcsd->todo_mask & HVCS_TRY_WRITE) {
 551                 /* won't send partial writes */
 552                 sent = hvc_put_chars(unit_address,
 553                                 &hvcsd->buffer[0],
 554                                 hvcsd->chars_in_buffer );
 555                 if (sent > 0) {
 556                         hvcsd->chars_in_buffer = 0;
 557                         /* wmb(); */
 558                         hvcsd->todo_mask &= ~(HVCS_TRY_WRITE);
 559                         /* wmb(); */
 560 
 561                         /*
 562                          * We are still obligated to deliver the data to the
 563                          * hypervisor even if the tty has been closed because
 564                          * we committed to delivering it.  But don't try to wake
 565                          * a non-existent tty.
 566                          */
 567                         if (tty) {
 568                                 tty_wakeup(tty);
 569                         }
 570                 }
 571         }
 572 }
 573 
 574 static int hvcs_io(struct hvcs_struct *hvcsd)
 575 {
 576         uint32_t unit_address;
 577         struct tty_struct *tty;
 578         char buf[HVCS_BUFF_LEN] __ALIGNED__;
 579         unsigned long flags;
 580         int got = 0;
 581 
 582         spin_lock_irqsave(&hvcsd->lock, flags);
 583 
 584         unit_address = hvcsd->vdev->unit_address;
 585         tty = hvcsd->port.tty;
 586 
 587         hvcs_try_write(hvcsd);
 588 
 589         if (!tty || tty_throttled(tty)) {
 590                 hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 591                 goto bail;
 592         } else if (!(hvcsd->todo_mask & (HVCS_READ_MASK)))
 593                 goto bail;
 594 
 595         /* remove the read masks */
 596         hvcsd->todo_mask &= ~(HVCS_READ_MASK);
 597 
 598         if (tty_buffer_request_room(&hvcsd->port, HVCS_BUFF_LEN) >= HVCS_BUFF_LEN) {
 599                 got = hvc_get_chars(unit_address,
 600                                 &buf[0],
 601                                 HVCS_BUFF_LEN);
 602                 tty_insert_flip_string(&hvcsd->port, buf, got);
 603         }
 604 
 605         /* Give the TTY time to process the data we just sent. */
 606         if (got)
 607                 hvcsd->todo_mask |= HVCS_QUICK_READ;
 608 
 609         spin_unlock_irqrestore(&hvcsd->lock, flags);
 610         /* This is synch because tty->low_latency == 1 */
 611         if(got)
 612                 tty_flip_buffer_push(&hvcsd->port);
 613 
 614         if (!got) {
 615                 /* Do this _after_ the flip_buffer_push */
 616                 spin_lock_irqsave(&hvcsd->lock, flags);
 617                 vio_enable_interrupts(hvcsd->vdev);
 618                 spin_unlock_irqrestore(&hvcsd->lock, flags);
 619         }
 620 
 621         return hvcsd->todo_mask;
 622 
 623  bail:
 624         spin_unlock_irqrestore(&hvcsd->lock, flags);
 625         return hvcsd->todo_mask;
 626 }
 627 
 628 static int khvcsd(void *unused)
 629 {
 630         struct hvcs_struct *hvcsd;
 631         int hvcs_todo_mask;
 632 
 633         __set_current_state(TASK_RUNNING);
 634 
 635         do {
 636                 hvcs_todo_mask = 0;
 637                 hvcs_kicked = 0;
 638                 wmb();
 639 
 640                 spin_lock(&hvcs_structs_lock);
 641                 list_for_each_entry(hvcsd, &hvcs_structs, next) {
 642                         hvcs_todo_mask |= hvcs_io(hvcsd);
 643                 }
 644                 spin_unlock(&hvcs_structs_lock);
 645 
 646                 /*
 647                  * If any of the hvcs adapters want to try a write or quick read
 648                  * don't schedule(), yield a smidgen then execute the hvcs_io
 649                  * thread again for those that want the write.
 650                  */
 651                  if (hvcs_todo_mask & (HVCS_TRY_WRITE | HVCS_QUICK_READ)) {
 652                         yield();
 653                         continue;
 654                 }
 655 
 656                 set_current_state(TASK_INTERRUPTIBLE);
 657                 if (!hvcs_kicked)
 658                         schedule();
 659                 __set_current_state(TASK_RUNNING);
 660         } while (!kthread_should_stop());
 661 
 662         return 0;
 663 }
 664 
 665 static const struct vio_device_id hvcs_driver_table[] = {
 666         {"serial-server", "hvterm2"},
 667         { "", "" }
 668 };
 669 MODULE_DEVICE_TABLE(vio, hvcs_driver_table);
 670 
 671 static void hvcs_return_index(int index)
 672 {
 673         /* Paranoia check */
 674         if (!hvcs_index_list)
 675                 return;
 676         if (index < 0 || index >= hvcs_index_count)
 677                 return;
 678         if (hvcs_index_list[index] == -1)
 679                 return;
 680         else
 681                 hvcs_index_list[index] = -1;
 682 }
 683 
 684 static void hvcs_destruct_port(struct tty_port *p)
 685 {
 686         struct hvcs_struct *hvcsd = container_of(p, struct hvcs_struct, port);
 687         struct vio_dev *vdev;
 688         unsigned long flags;
 689 
 690         spin_lock(&hvcs_structs_lock);
 691         spin_lock_irqsave(&hvcsd->lock, flags);
 692 
 693         /* the list_del poisons the pointers */
 694         list_del(&(hvcsd->next));
 695 
 696         if (hvcsd->connected == 1) {
 697                 hvcs_partner_free(hvcsd);
 698                 printk(KERN_INFO "HVCS: Closed vty-server@%X and"
 699                                 " partner vty@%X:%d connection.\n",
 700                                 hvcsd->vdev->unit_address,
 701                                 hvcsd->p_unit_address,
 702                                 (uint32_t)hvcsd->p_partition_ID);
 703         }
 704         printk(KERN_INFO "HVCS: Destroyed hvcs_struct for vty-server@%X.\n",
 705                         hvcsd->vdev->unit_address);
 706 
 707         vdev = hvcsd->vdev;
 708         hvcsd->vdev = NULL;
 709 
 710         hvcsd->p_unit_address = 0;
 711         hvcsd->p_partition_ID = 0;
 712         hvcs_return_index(hvcsd->index);
 713         memset(&hvcsd->p_location_code[0], 0x00, HVCS_CLC_LENGTH + 1);
 714 
 715         spin_unlock_irqrestore(&hvcsd->lock, flags);
 716         spin_unlock(&hvcs_structs_lock);
 717 
 718         sysfs_remove_group(&vdev->dev.kobj, &hvcs_attr_group);
 719 
 720         kfree(hvcsd);
 721 }
 722 
 723 static const struct tty_port_operations hvcs_port_ops = {
 724         .destruct = hvcs_destruct_port,
 725 };
 726 
 727 static int hvcs_get_index(void)
 728 {
 729         int i;
 730         /* Paranoia check */
 731         if (!hvcs_index_list) {
 732                 printk(KERN_ERR "HVCS: hvcs_index_list NOT valid!.\n");
 733                 return -EFAULT;
 734         }
 735         /* Find the numerically lowest first free index. */
 736         for(i = 0; i < hvcs_index_count; i++) {
 737                 if (hvcs_index_list[i] == -1) {
 738                         hvcs_index_list[i] = 0;
 739                         return i;
 740                 }
 741         }
 742         return -1;
 743 }
 744 
 745 static int hvcs_probe(
 746         struct vio_dev *dev,
 747         const struct vio_device_id *id)
 748 {
 749         struct hvcs_struct *hvcsd;
 750         int index, rc;
 751         int retval;
 752 
 753         if (!dev || !id) {
 754                 printk(KERN_ERR "HVCS: probed with invalid parameter.\n");
 755                 return -EPERM;
 756         }
 757 
 758         /* Make sure we are properly initialized */
 759         rc = hvcs_initialize();
 760         if (rc) {
 761                 pr_err("HVCS: Failed to initialize core driver.\n");
 762                 return rc;
 763         }
 764 
 765         /* early to avoid cleanup on failure */
 766         index = hvcs_get_index();
 767         if (index < 0) {
 768                 return -EFAULT;
 769         }
 770 
 771         hvcsd = kzalloc(sizeof(*hvcsd), GFP_KERNEL);
 772         if (!hvcsd)
 773                 return -ENODEV;
 774 
 775         tty_port_init(&hvcsd->port);
 776         hvcsd->port.ops = &hvcs_port_ops;
 777         spin_lock_init(&hvcsd->lock);
 778 
 779         hvcsd->vdev = dev;
 780         dev_set_drvdata(&dev->dev, hvcsd);
 781 
 782         hvcsd->index = index;
 783 
 784         /* hvcsd->index = ++hvcs_struct_count; */
 785         hvcsd->chars_in_buffer = 0;
 786         hvcsd->todo_mask = 0;
 787         hvcsd->connected = 0;
 788 
 789         /*
 790          * This will populate the hvcs_struct's partner info fields for the
 791          * first time.
 792          */
 793         if (hvcs_get_pi(hvcsd)) {
 794                 printk(KERN_ERR "HVCS: Failed to fetch partner"
 795                         " info for vty-server@%X on device probe.\n",
 796                         hvcsd->vdev->unit_address);
 797         }
 798 
 799         /*
 800          * If a user app opens a tty that corresponds to this vty-server before
 801          * the hvcs_struct has been added to the devices list then the user app
 802          * will get -ENODEV.
 803          */
 804         spin_lock(&hvcs_structs_lock);
 805         list_add_tail(&(hvcsd->next), &hvcs_structs);
 806         spin_unlock(&hvcs_structs_lock);
 807 
 808         retval = sysfs_create_group(&dev->dev.kobj, &hvcs_attr_group);
 809         if (retval) {
 810                 printk(KERN_ERR "HVCS: Can't create sysfs attrs for vty-server@%X\n",
 811                        hvcsd->vdev->unit_address);
 812                 return retval;
 813         }
 814 
 815         printk(KERN_INFO "HVCS: vty-server@%X added to the vio bus.\n", dev->unit_address);
 816 
 817         /*
 818          * DON'T enable interrupts here because there is no user to receive the
 819          * data.
 820          */
 821         return 0;
 822 }
 823 
 824 static int hvcs_remove(struct vio_dev *dev)
 825 {
 826         struct hvcs_struct *hvcsd = dev_get_drvdata(&dev->dev);
 827         unsigned long flags;
 828         struct tty_struct *tty;
 829 
 830         if (!hvcsd)
 831                 return -ENODEV;
 832 
 833         /* By this time the vty-server won't be getting any more interrupts */
 834 
 835         spin_lock_irqsave(&hvcsd->lock, flags);
 836 
 837         tty = hvcsd->port.tty;
 838 
 839         spin_unlock_irqrestore(&hvcsd->lock, flags);
 840 
 841         /*
 842          * Let the last holder of this object cause it to be removed, which
 843          * would probably be tty_hangup below.
 844          */
 845         tty_port_put(&hvcsd->port);
 846 
 847         /*
 848          * The hangup is a scheduled function which will auto chain call
 849          * hvcs_hangup.  The tty should always be valid at this time unless a
 850          * simultaneous tty close already cleaned up the hvcs_struct.
 851          */
 852         if (tty)
 853                 tty_hangup(tty);
 854 
 855         printk(KERN_INFO "HVCS: vty-server@%X removed from the"
 856                         " vio bus.\n", dev->unit_address);
 857         return 0;
 858 };
 859 
 860 static struct vio_driver hvcs_vio_driver = {
 861         .id_table       = hvcs_driver_table,
 862         .probe          = hvcs_probe,
 863         .remove         = hvcs_remove,
 864         .name           = hvcs_driver_name,
 865 };
 866 
 867 /* Only called from hvcs_get_pi please */
 868 static void hvcs_set_pi(struct hvcs_partner_info *pi, struct hvcs_struct *hvcsd)
 869 {
 870         hvcsd->p_unit_address = pi->unit_address;
 871         hvcsd->p_partition_ID  = pi->partition_ID;
 872 
 873         /* copy the null-term char too */
 874         strlcpy(hvcsd->p_location_code, pi->location_code,
 875                 sizeof(hvcsd->p_location_code));
 876 }
 877 
 878 /*
 879  * Traverse the list and add the partner info that is found to the hvcs_struct
 880  * struct entry. NOTE: At this time I know that partner info will return a
 881  * single entry but in the future there may be multiple partner info entries per
 882  * vty-server and you'll want to zero out that list and reset it.  If for some
 883  * reason you have an old version of this driver but there IS more than one
 884  * partner info then hvcsd->p_* will hold the last partner info data from the
 885  * firmware query.  A good way to update this code would be to replace the three
 886  * partner info fields in hvcs_struct with a list of hvcs_partner_info
 887  * instances.
 888  *
 889  * This function must be called with the hvcsd->lock held.
 890  */
 891 static int hvcs_get_pi(struct hvcs_struct *hvcsd)
 892 {
 893         struct hvcs_partner_info *pi;
 894         uint32_t unit_address = hvcsd->vdev->unit_address;
 895         struct list_head head;
 896         int retval;
 897 
 898         spin_lock(&hvcs_pi_lock);
 899         if (!hvcs_pi_buff) {
 900                 spin_unlock(&hvcs_pi_lock);
 901                 return -EFAULT;
 902         }
 903         retval = hvcs_get_partner_info(unit_address, &head, hvcs_pi_buff);
 904         spin_unlock(&hvcs_pi_lock);
 905         if (retval) {
 906                 printk(KERN_ERR "HVCS: Failed to fetch partner"
 907                         " info for vty-server@%x.\n", unit_address);
 908                 return retval;
 909         }
 910 
 911         /* nixes the values if the partner vty went away */
 912         hvcsd->p_unit_address = 0;
 913         hvcsd->p_partition_ID = 0;
 914 
 915         list_for_each_entry(pi, &head, node)
 916                 hvcs_set_pi(pi, hvcsd);
 917 
 918         hvcs_free_partner_info(&head);
 919         return 0;
 920 }
 921 
 922 /*
 923  * This function is executed by the driver "rescan" sysfs entry.  It shouldn't
 924  * be executed elsewhere, in order to prevent deadlock issues.
 925  */
 926 static int hvcs_rescan_devices_list(void)
 927 {
 928         struct hvcs_struct *hvcsd;
 929         unsigned long flags;
 930 
 931         spin_lock(&hvcs_structs_lock);
 932 
 933         list_for_each_entry(hvcsd, &hvcs_structs, next) {
 934                 spin_lock_irqsave(&hvcsd->lock, flags);
 935                 hvcs_get_pi(hvcsd);
 936                 spin_unlock_irqrestore(&hvcsd->lock, flags);
 937         }
 938 
 939         spin_unlock(&hvcs_structs_lock);
 940 
 941         return 0;
 942 }
 943 
 944 /*
 945  * Farm this off into its own function because it could be more complex once
 946  * multiple partners support is added. This function should be called with
 947  * the hvcsd->lock held.
 948  */
 949 static int hvcs_has_pi(struct hvcs_struct *hvcsd)
 950 {
 951         if ((!hvcsd->p_unit_address) || (!hvcsd->p_partition_ID))
 952                 return 0;
 953         return 1;
 954 }
 955 
 956 /*
 957  * NOTE: It is possible that the super admin removed a partner vty and then
 958  * added a different vty as the new partner.
 959  *
 960  * This function must be called with the hvcsd->lock held.
 961  */
 962 static int hvcs_partner_connect(struct hvcs_struct *hvcsd)
 963 {
 964         int retval;
 965         unsigned int unit_address = hvcsd->vdev->unit_address;
 966 
 967         /*
 968          * If there wasn't any pi when the device was added it doesn't meant
 969          * there isn't any now.  This driver isn't notified when a new partner
 970          * vty is added to a vty-server so we discover changes on our own.
 971          * Please see comments in hvcs_register_connection() for justification
 972          * of this bizarre code.
 973          */
 974         retval = hvcs_register_connection(unit_address,
 975                         hvcsd->p_partition_ID,
 976                         hvcsd->p_unit_address);
 977         if (!retval) {
 978                 hvcsd->connected = 1;
 979                 return 0;
 980         } else if (retval != -EINVAL)
 981                 return retval;
 982 
 983         /*
 984          * As per the spec re-get the pi and try again if -EINVAL after the
 985          * first connection attempt.
 986          */
 987         if (hvcs_get_pi(hvcsd))
 988                 return -ENOMEM;
 989 
 990         if (!hvcs_has_pi(hvcsd))
 991                 return -ENODEV;
 992 
 993         retval = hvcs_register_connection(unit_address,
 994                         hvcsd->p_partition_ID,
 995                         hvcsd->p_unit_address);
 996         if (retval != -EINVAL) {
 997                 hvcsd->connected = 1;
 998                 return retval;
 999         }
1000 
1001         /*
1002          * EBUSY is the most likely scenario though the vty could have been
1003          * removed or there really could be an hcall error due to the parameter
1004          * data but thanks to ambiguous firmware return codes we can't really
1005          * tell.
1006          */
1007         printk(KERN_INFO "HVCS: vty-server or partner"
1008                         " vty is busy.  Try again later.\n");
1009         return -EBUSY;
1010 }
1011 
1012 /* This function must be called with the hvcsd->lock held */
1013 static void hvcs_partner_free(struct hvcs_struct *hvcsd)
1014 {
1015         int retval;
1016         do {
1017                 retval = hvcs_free_connection(hvcsd->vdev->unit_address);
1018         } while (retval == -EBUSY);
1019         hvcsd->connected = 0;
1020 }
1021 
1022 /* This helper function must be called WITHOUT the hvcsd->lock held */
1023 static int hvcs_enable_device(struct hvcs_struct *hvcsd, uint32_t unit_address,
1024                 unsigned int irq, struct vio_dev *vdev)
1025 {
1026         unsigned long flags;
1027         int rc;
1028 
1029         /*
1030          * It is possible that the vty-server was removed between the time that
1031          * the conn was registered and now.
1032          */
1033         rc = request_irq(irq, &hvcs_handle_interrupt, 0, "ibmhvcs", hvcsd);
1034         if (!rc) {
1035                 /*
1036                  * It is possible the vty-server was removed after the irq was
1037                  * requested but before we have time to enable interrupts.
1038                  */
1039                 if (vio_enable_interrupts(vdev) == H_SUCCESS)
1040                         return 0;
1041                 else {
1042                         printk(KERN_ERR "HVCS: int enable failed for"
1043                                         " vty-server@%X.\n", unit_address);
1044                         free_irq(irq, hvcsd);
1045                 }
1046         } else
1047                 printk(KERN_ERR "HVCS: irq req failed for"
1048                                 " vty-server@%X.\n", unit_address);
1049 
1050         spin_lock_irqsave(&hvcsd->lock, flags);
1051         hvcs_partner_free(hvcsd);
1052         spin_unlock_irqrestore(&hvcsd->lock, flags);
1053 
1054         return rc;
1055 
1056 }
1057 
1058 /*
1059  * This always increments the kref ref count if the call is successful.
1060  * Please remember to dec when you are done with the instance.
1061  *
1062  * NOTICE: Do NOT hold either the hvcs_struct.lock or hvcs_structs_lock when
1063  * calling this function or you will get deadlock.
1064  */
1065 static struct hvcs_struct *hvcs_get_by_index(int index)
1066 {
1067         struct hvcs_struct *hvcsd;
1068         unsigned long flags;
1069 
1070         spin_lock(&hvcs_structs_lock);
1071         list_for_each_entry(hvcsd, &hvcs_structs, next) {
1072                 spin_lock_irqsave(&hvcsd->lock, flags);
1073                 if (hvcsd->index == index) {
1074                         tty_port_get(&hvcsd->port);
1075                         spin_unlock_irqrestore(&hvcsd->lock, flags);
1076                         spin_unlock(&hvcs_structs_lock);
1077                         return hvcsd;
1078                 }
1079                 spin_unlock_irqrestore(&hvcsd->lock, flags);
1080         }
1081         spin_unlock(&hvcs_structs_lock);
1082 
1083         return NULL;
1084 }
1085 
1086 static int hvcs_install(struct tty_driver *driver, struct tty_struct *tty)
1087 {
1088         struct hvcs_struct *hvcsd;
1089         struct vio_dev *vdev;
1090         unsigned long unit_address, flags;
1091         unsigned int irq;
1092         int retval;
1093 
1094         /*
1095          * Is there a vty-server that shares the same index?
1096          * This function increments the kref index.
1097          */
1098         hvcsd = hvcs_get_by_index(tty->index);
1099         if (!hvcsd) {
1100                 printk(KERN_WARNING "HVCS: open failed, no device associated"
1101                                 " with tty->index %d.\n", tty->index);
1102                 return -ENODEV;
1103         }
1104 
1105         spin_lock_irqsave(&hvcsd->lock, flags);
1106 
1107         if (hvcsd->connected == 0) {
1108                 retval = hvcs_partner_connect(hvcsd);
1109                 if (retval) {
1110                         spin_unlock_irqrestore(&hvcsd->lock, flags);
1111                         printk(KERN_WARNING "HVCS: partner connect failed.\n");
1112                         goto err_put;
1113                 }
1114         }
1115 
1116         hvcsd->port.count = 0;
1117         hvcsd->port.tty = tty;
1118         tty->driver_data = hvcsd;
1119 
1120         memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1121 
1122         /*
1123          * Save these in the spinlock for the enable operations that need them
1124          * outside of the spinlock.
1125          */
1126         irq = hvcsd->vdev->irq;
1127         vdev = hvcsd->vdev;
1128         unit_address = hvcsd->vdev->unit_address;
1129 
1130         hvcsd->todo_mask |= HVCS_SCHED_READ;
1131         spin_unlock_irqrestore(&hvcsd->lock, flags);
1132 
1133         /*
1134          * This must be done outside of the spinlock because it requests irqs
1135          * and will grab the spinlock and free the connection if it fails.
1136          */
1137         retval = hvcs_enable_device(hvcsd, unit_address, irq, vdev);
1138         if (retval) {
1139                 printk(KERN_WARNING "HVCS: enable device failed.\n");
1140                 goto err_put;
1141         }
1142 
1143         retval = tty_port_install(&hvcsd->port, driver, tty);
1144         if (retval)
1145                 goto err_irq;
1146 
1147         return 0;
1148 err_irq:
1149         spin_lock_irqsave(&hvcsd->lock, flags);
1150         vio_disable_interrupts(hvcsd->vdev);
1151         spin_unlock_irqrestore(&hvcsd->lock, flags);
1152         free_irq(irq, hvcsd);
1153 err_put:
1154         tty_port_put(&hvcsd->port);
1155 
1156         return retval;
1157 }
1158 
1159 /*
1160  * This is invoked via the tty_open interface when a user app connects to the
1161  * /dev node.
1162  */
1163 static int hvcs_open(struct tty_struct *tty, struct file *filp)
1164 {
1165         struct hvcs_struct *hvcsd = tty->driver_data;
1166         unsigned long flags;
1167 
1168         spin_lock_irqsave(&hvcsd->lock, flags);
1169         hvcsd->port.count++;
1170         hvcsd->todo_mask |= HVCS_SCHED_READ;
1171         spin_unlock_irqrestore(&hvcsd->lock, flags);
1172 
1173         hvcs_kick();
1174 
1175         printk(KERN_INFO "HVCS: vty-server@%X connection opened.\n",
1176                 hvcsd->vdev->unit_address );
1177 
1178         return 0;
1179 }
1180 
1181 static void hvcs_close(struct tty_struct *tty, struct file *filp)
1182 {
1183         struct hvcs_struct *hvcsd;
1184         unsigned long flags;
1185         int irq;
1186 
1187         /*
1188          * Is someone trying to close the file associated with this device after
1189          * we have hung up?  If so tty->driver_data wouldn't be valid.
1190          */
1191         if (tty_hung_up_p(filp))
1192                 return;
1193 
1194         /*
1195          * No driver_data means that this close was probably issued after a
1196          * failed hvcs_open by the tty layer's release_dev() api and we can just
1197          * exit cleanly.
1198          */
1199         if (!tty->driver_data)
1200                 return;
1201 
1202         hvcsd = tty->driver_data;
1203 
1204         spin_lock_irqsave(&hvcsd->lock, flags);
1205         if (--hvcsd->port.count == 0) {
1206 
1207                 vio_disable_interrupts(hvcsd->vdev);
1208 
1209                 /*
1210                  * NULL this early so that the kernel_thread doesn't try to
1211                  * execute any operations on the TTY even though it is obligated
1212                  * to deliver any pending I/O to the hypervisor.
1213                  */
1214                 hvcsd->port.tty = NULL;
1215 
1216                 irq = hvcsd->vdev->irq;
1217                 spin_unlock_irqrestore(&hvcsd->lock, flags);
1218 
1219                 tty_wait_until_sent(tty, HVCS_CLOSE_WAIT);
1220 
1221                 /*
1222                  * This line is important because it tells hvcs_open that this
1223                  * device needs to be re-configured the next time hvcs_open is
1224                  * called.
1225                  */
1226                 tty->driver_data = NULL;
1227 
1228                 free_irq(irq, hvcsd);
1229                 return;
1230         } else if (hvcsd->port.count < 0) {
1231                 printk(KERN_ERR "HVCS: vty-server@%X open_count: %d is mismanaged.\n",
1232                 hvcsd->vdev->unit_address, hvcsd->port.count);
1233         }
1234 
1235         spin_unlock_irqrestore(&hvcsd->lock, flags);
1236 }
1237 
1238 static void hvcs_cleanup(struct tty_struct * tty)
1239 {
1240         struct hvcs_struct *hvcsd = tty->driver_data;
1241 
1242         tty_port_put(&hvcsd->port);
1243 }
1244 
1245 static void hvcs_hangup(struct tty_struct * tty)
1246 {
1247         struct hvcs_struct *hvcsd = tty->driver_data;
1248         unsigned long flags;
1249         int temp_open_count;
1250         int irq;
1251 
1252         spin_lock_irqsave(&hvcsd->lock, flags);
1253         /* Preserve this so that we know how many kref refs to put */
1254         temp_open_count = hvcsd->port.count;
1255 
1256         /*
1257          * Don't kref put inside the spinlock because the destruction
1258          * callback may use the spinlock and it may get called before the
1259          * spinlock has been released.
1260          */
1261         vio_disable_interrupts(hvcsd->vdev);
1262 
1263         hvcsd->todo_mask = 0;
1264 
1265         /* I don't think the tty needs the hvcs_struct pointer after a hangup */
1266         tty->driver_data = NULL;
1267         hvcsd->port.tty = NULL;
1268 
1269         hvcsd->port.count = 0;
1270 
1271         /* This will drop any buffered data on the floor which is OK in a hangup
1272          * scenario. */
1273         memset(&hvcsd->buffer[0], 0x00, HVCS_BUFF_LEN);
1274         hvcsd->chars_in_buffer = 0;
1275 
1276         irq = hvcsd->vdev->irq;
1277 
1278         spin_unlock_irqrestore(&hvcsd->lock, flags);
1279 
1280         free_irq(irq, hvcsd);
1281 
1282         /*
1283          * We need to kref_put() for every open_count we have since the
1284          * tty_hangup() function doesn't invoke a close per open connection on a
1285          * non-console device.
1286          */
1287         while(temp_open_count) {
1288                 --temp_open_count;
1289                 /*
1290                  * The final put will trigger destruction of the hvcs_struct.
1291                  * NOTE:  If this hangup was signaled from user space then the
1292                  * final put will never happen.
1293                  */
1294                 tty_port_put(&hvcsd->port);
1295         }
1296 }
1297 
1298 /*
1299  * NOTE: This is almost always from_user since user level apps interact with the
1300  * /dev nodes. I'm trusting that if hvcs_write gets called and interrupted by
1301  * hvcs_remove (which removes the target device and executes tty_hangup()) that
1302  * tty_hangup will allow hvcs_write time to complete execution before it
1303  * terminates our device.
1304  */
1305 static int hvcs_write(struct tty_struct *tty,
1306                 const unsigned char *buf, int count)
1307 {
1308         struct hvcs_struct *hvcsd = tty->driver_data;
1309         unsigned int unit_address;
1310         const unsigned char *charbuf;
1311         unsigned long flags;
1312         int total_sent = 0;
1313         int tosend = 0;
1314         int result = 0;
1315 
1316         /*
1317          * If they don't check the return code off of their open they may
1318          * attempt this even if there is no connected device.
1319          */
1320         if (!hvcsd)
1321                 return -ENODEV;
1322 
1323         /* Reasonable size to prevent user level flooding */
1324         if (count > HVCS_MAX_FROM_USER) {
1325                 printk(KERN_WARNING "HVCS write: count being truncated to"
1326                                 " HVCS_MAX_FROM_USER.\n");
1327                 count = HVCS_MAX_FROM_USER;
1328         }
1329 
1330         charbuf = buf;
1331 
1332         spin_lock_irqsave(&hvcsd->lock, flags);
1333 
1334         /*
1335          * Somehow an open succeeded but the device was removed or the
1336          * connection terminated between the vty-server and partner vty during
1337          * the middle of a write operation?  This is a crummy place to do this
1338          * but we want to keep it all in the spinlock.
1339          */
1340         if (hvcsd->port.count <= 0) {
1341                 spin_unlock_irqrestore(&hvcsd->lock, flags);
1342                 return -ENODEV;
1343         }
1344 
1345         unit_address = hvcsd->vdev->unit_address;
1346 
1347         while (count > 0) {
1348                 tosend = min(count, (HVCS_BUFF_LEN - hvcsd->chars_in_buffer));
1349                 /*
1350                  * No more space, this probably means that the last call to
1351                  * hvcs_write() didn't succeed and the buffer was filled up.
1352                  */
1353                 if (!tosend)
1354                         break;
1355 
1356                 memcpy(&hvcsd->buffer[hvcsd->chars_in_buffer],
1357                                 &charbuf[total_sent],
1358                                 tosend);
1359 
1360                 hvcsd->chars_in_buffer += tosend;
1361 
1362                 result = 0;
1363 
1364                 /*
1365                  * If this is true then we don't want to try writing to the
1366                  * hypervisor because that is the kernel_threads job now.  We'll
1367                  * just add to the buffer.
1368                  */
1369                 if (!(hvcsd->todo_mask & HVCS_TRY_WRITE))
1370                         /* won't send partial writes */
1371                         result = hvc_put_chars(unit_address,
1372                                         &hvcsd->buffer[0],
1373                                         hvcsd->chars_in_buffer);
1374 
1375                 /*
1376                  * Since we know we have enough room in hvcsd->buffer for
1377                  * tosend we record that it was sent regardless of whether the
1378                  * hypervisor actually took it because we have it buffered.
1379                  */
1380                 total_sent+=tosend;
1381                 count-=tosend;
1382                 if (result == 0) {
1383                         hvcsd->todo_mask |= HVCS_TRY_WRITE;
1384                         hvcs_kick();
1385                         break;
1386                 }
1387 
1388                 hvcsd->chars_in_buffer = 0;
1389                 /*
1390                  * Test after the chars_in_buffer reset otherwise this could
1391                  * deadlock our writes if hvc_put_chars fails.
1392                  */
1393                 if (result < 0)
1394                         break;
1395         }
1396 
1397         spin_unlock_irqrestore(&hvcsd->lock, flags);
1398 
1399         if (result == -1)
1400                 return -EIO;
1401         else
1402                 return total_sent;
1403 }
1404 
1405 /*
1406  * This is really asking how much can we guarantee that we can send or that we
1407  * absolutely WILL BUFFER if we can't send it.  This driver MUST honor the
1408  * return value, hence the reason for hvcs_struct buffering.
1409  */
1410 static int hvcs_write_room(struct tty_struct *tty)
1411 {
1412         struct hvcs_struct *hvcsd = tty->driver_data;
1413 
1414         if (!hvcsd || hvcsd->port.count <= 0)
1415                 return 0;
1416 
1417         return HVCS_BUFF_LEN - hvcsd->chars_in_buffer;
1418 }
1419 
1420 static int hvcs_chars_in_buffer(struct tty_struct *tty)
1421 {
1422         struct hvcs_struct *hvcsd = tty->driver_data;
1423 
1424         return hvcsd->chars_in_buffer;
1425 }
1426 
1427 static const struct tty_operations hvcs_ops = {
1428         .install = hvcs_install,
1429         .open = hvcs_open,
1430         .close = hvcs_close,
1431         .cleanup = hvcs_cleanup,
1432         .hangup = hvcs_hangup,
1433         .write = hvcs_write,
1434         .write_room = hvcs_write_room,
1435         .chars_in_buffer = hvcs_chars_in_buffer,
1436         .unthrottle = hvcs_unthrottle,
1437         .throttle = hvcs_throttle,
1438 };
1439 
1440 static int hvcs_alloc_index_list(int n)
1441 {
1442         int i;
1443 
1444         hvcs_index_list = kmalloc_array(n, sizeof(hvcs_index_count),
1445                                         GFP_KERNEL);
1446         if (!hvcs_index_list)
1447                 return -ENOMEM;
1448         hvcs_index_count = n;
1449         for (i = 0; i < hvcs_index_count; i++)
1450                 hvcs_index_list[i] = -1;
1451         return 0;
1452 }
1453 
1454 static void hvcs_free_index_list(void)
1455 {
1456         /* Paranoia check to be thorough. */
1457         kfree(hvcs_index_list);
1458         hvcs_index_list = NULL;
1459         hvcs_index_count = 0;
1460 }
1461 
1462 static int hvcs_initialize(void)
1463 {
1464         int rc, num_ttys_to_alloc;
1465 
1466         mutex_lock(&hvcs_init_mutex);
1467         if (hvcs_task) {
1468                 mutex_unlock(&hvcs_init_mutex);
1469                 return 0;
1470         }
1471 
1472         /* Has the user specified an overload with an insmod param? */
1473         if (hvcs_parm_num_devs <= 0 ||
1474                 (hvcs_parm_num_devs > HVCS_MAX_SERVER_ADAPTERS)) {
1475                 num_ttys_to_alloc = HVCS_DEFAULT_SERVER_ADAPTERS;
1476         } else
1477                 num_ttys_to_alloc = hvcs_parm_num_devs;
1478 
1479         hvcs_tty_driver = alloc_tty_driver(num_ttys_to_alloc);
1480         if (!hvcs_tty_driver) {
1481                 mutex_unlock(&hvcs_init_mutex);
1482                 return -ENOMEM;
1483         }
1484 
1485         if (hvcs_alloc_index_list(num_ttys_to_alloc)) {
1486                 rc = -ENOMEM;
1487                 goto index_fail;
1488         }
1489 
1490         hvcs_tty_driver->driver_name = hvcs_driver_name;
1491         hvcs_tty_driver->name = hvcs_device_node;
1492 
1493         /*
1494          * We'll let the system assign us a major number, indicated by leaving
1495          * it blank.
1496          */
1497 
1498         hvcs_tty_driver->minor_start = HVCS_MINOR_START;
1499         hvcs_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
1500 
1501         /*
1502          * We role our own so that we DONT ECHO.  We can't echo because the
1503          * device we are connecting to already echoes by default and this would
1504          * throw us into a horrible recursive echo-echo-echo loop.
1505          */
1506         hvcs_tty_driver->init_termios = hvcs_tty_termios;
1507         hvcs_tty_driver->flags = TTY_DRIVER_REAL_RAW;
1508 
1509         tty_set_operations(hvcs_tty_driver, &hvcs_ops);
1510 
1511         /*
1512          * The following call will result in sysfs entries that denote the
1513          * dynamically assigned major and minor numbers for our devices.
1514          */
1515         if (tty_register_driver(hvcs_tty_driver)) {
1516                 printk(KERN_ERR "HVCS: registration as a tty driver failed.\n");
1517                 rc = -EIO;
1518                 goto register_fail;
1519         }
1520 
1521         hvcs_pi_buff = (unsigned long *) __get_free_page(GFP_KERNEL);
1522         if (!hvcs_pi_buff) {
1523                 rc = -ENOMEM;
1524                 goto buff_alloc_fail;
1525         }
1526 
1527         hvcs_task = kthread_run(khvcsd, NULL, "khvcsd");
1528         if (IS_ERR(hvcs_task)) {
1529                 printk(KERN_ERR "HVCS: khvcsd creation failed.\n");
1530                 rc = -EIO;
1531                 goto kthread_fail;
1532         }
1533         mutex_unlock(&hvcs_init_mutex);
1534         return 0;
1535 
1536 kthread_fail:
1537         free_page((unsigned long)hvcs_pi_buff);
1538 buff_alloc_fail:
1539         tty_unregister_driver(hvcs_tty_driver);
1540 register_fail:
1541         hvcs_free_index_list();
1542 index_fail:
1543         put_tty_driver(hvcs_tty_driver);
1544         hvcs_tty_driver = NULL;
1545         mutex_unlock(&hvcs_init_mutex);
1546         return rc;
1547 }
1548 
1549 static int __init hvcs_module_init(void)
1550 {
1551         int rc = vio_register_driver(&hvcs_vio_driver);
1552         if (rc) {
1553                 printk(KERN_ERR "HVCS: can't register vio driver\n");
1554                 return rc;
1555         }
1556 
1557         pr_info("HVCS: Driver registered.\n");
1558 
1559         /* This needs to be done AFTER the vio_register_driver() call or else
1560          * the kobjects won't be initialized properly.
1561          */
1562         rc = driver_create_file(&(hvcs_vio_driver.driver), &driver_attr_rescan);
1563         if (rc)
1564                 pr_warn("HVCS: Failed to create rescan file (err %d)\n", rc);
1565 
1566         return 0;
1567 }
1568 
1569 static void __exit hvcs_module_exit(void)
1570 {
1571         /*
1572          * This driver receives hvcs_remove callbacks for each device upon
1573          * module removal.
1574          */
1575         vio_unregister_driver(&hvcs_vio_driver);
1576         if (!hvcs_task)
1577                 return;
1578 
1579         /*
1580          * This synchronous operation  will wake the khvcsd kthread if it is
1581          * asleep and will return when khvcsd has terminated.
1582          */
1583         kthread_stop(hvcs_task);
1584 
1585         spin_lock(&hvcs_pi_lock);
1586         free_page((unsigned long)hvcs_pi_buff);
1587         hvcs_pi_buff = NULL;
1588         spin_unlock(&hvcs_pi_lock);
1589 
1590         driver_remove_file(&hvcs_vio_driver.driver, &driver_attr_rescan);
1591 
1592         tty_unregister_driver(hvcs_tty_driver);
1593 
1594         hvcs_free_index_list();
1595 
1596         put_tty_driver(hvcs_tty_driver);
1597 
1598         printk(KERN_INFO "HVCS: driver module removed.\n");
1599 }
1600 
1601 module_init(hvcs_module_init);
1602 module_exit(hvcs_module_exit);
/* [<][>][^][v][top][bottom][index][help] */
root/drivers/tty/hvc/hvcs.c

DEFINITIONS
