arch/sh/kernel/apm.c

   1 /*
   2  * bios-less APM driver for hp680
   3  *
   4  * Copyright 2005 (c) Andriy Skulysh <askulysh@gmail.com>
   5  *
   6  * based on ARM APM driver by
   7  *  Jamey Hicks <jamey@crl.dec.com>
   8  *
   9  * adapted from the APM BIOS driver for Linux by
  10  *  Stephen Rothwell (sfr@linuxcare.com)
  11  *
  12  * APM 1.2 Reference:
  13  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
  14  *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
  15  *
  16  * [This document is available from Microsoft at:
  17  *    http://www.microsoft.com/hwdev/busbios/amp_12.htm]
  18  */
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/poll.h>
  22 #include <linux/timer.h>
  23 #include <linux/slab.h>
  24 #include <linux/proc_fs.h>
  25 #include <linux/miscdevice.h>
  26 #include <linux/apm_bios.h>
  27 #include <linux/pm.h>
  28 #include <linux/pm_legacy.h>
  29 #include <asm/apm.h>
  30
  31 #define MODNAME "apm"
  32
  33 /*
  34  * The apm_bios device is one of the misc char devices.
  35  * This is its minor number.
  36  */
  37 #define APM_MINOR_DEV                   134
  38
  39 /*
  40  * Maximum number of events stored
  41  */
  42 #define APM_MAX_EVENTS                  16
  43
  44 struct apm_queue {
  45         unsigned int            event_head;
  46         unsigned int            event_tail;
  47         apm_event_t             events[APM_MAX_EVENTS];
  48 };
  49
  50 /*
  51  * The per-file APM data
  52  */
  53 struct apm_user {
  54         struct list_head        list;
  55
  56         unsigned int            suser: 1;
  57         unsigned int            writer: 1;
  58         unsigned int            reader: 1;
  59
  60         int                     suspend_result;
  61         unsigned int            suspend_state;
  62 #define SUSPEND_NONE    0               /* no suspend pending */
  63 #define SUSPEND_PENDING 1               /* suspend pending read */
  64 #define SUSPEND_READ    2               /* suspend read, pending ack */
  65 #define SUSPEND_ACKED   3               /* suspend acked */
  66 #define SUSPEND_DONE    4               /* suspend completed */
  67
  68         struct apm_queue        queue;
  69 };
  70
  71 /*
  72  * Local variables
  73  */
  74 static int suspends_pending;
  75
  76 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
  77 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
  78
  79 /*
  80  * This is a list of everyone who has opened /dev/apm_bios
  81  */
  82 static DECLARE_RWSEM(user_list_lock);
  83 static LIST_HEAD(apm_user_list);
  84
  85 /*
  86  * kapmd info.  kapmd provides us a process context to handle
  87  * "APM" events within - specifically necessary if we're going
  88  * to be suspending the system.
  89  */
  90 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
  91 static DECLARE_COMPLETION(kapmd_exit);
  92 static DEFINE_SPINLOCK(kapmd_queue_lock);
  93 static struct apm_queue kapmd_queue;
  94
  95 int apm_suspended;
  96 EXPORT_SYMBOL(apm_suspended);
  97
  98 /* Platform-specific apm_read_proc(). */
  99 int (*apm_get_info)(char *buf, char **start, off_t fpos, int length);
 100 EXPORT_SYMBOL(apm_get_info);
 101
 102 /*
 103  * APM event queue management.
 104  */
 105 static inline int queue_empty(struct apm_queue *q)
 106 {
 107         return q->event_head == q->event_tail;
 108 }
 109
 110 static inline apm_event_t queue_get_event(struct apm_queue *q)
 111 {
 112         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 113         return q->events[q->event_tail];
 114 }
 115
 116 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 117 {
 118         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 119         if (q->event_head == q->event_tail) {
 120                 static int notified;
 121
 122                 if (notified++ == 0)
 123                         printk(KERN_ERR "apm: an event queue overflowed\n");
 124
 125                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 126         }
 127         q->events[q->event_head] = event;
 128 }
 129
 130 static void queue_event_one_user(struct apm_user *as, apm_event_t event)
 131 {
 132         if (as->suser && as->writer) {
 133                 switch (event) {
 134                 case APM_SYS_SUSPEND:
 135                 case APM_USER_SUSPEND:
 136                         /*
 137                          * If this user already has a suspend pending,
 138                          * don't queue another one.
 139                          */
 140                         if (as->suspend_state != SUSPEND_NONE)
 141                                 return;
 142
 143                         as->suspend_state = SUSPEND_PENDING;
 144                         suspends_pending++;
 145                         break;
 146                 }
 147         }
 148         queue_add_event(&as->queue, event);
 149 }
 150
 151 static void queue_event(apm_event_t event, struct apm_user *sender)
 152 {
 153         struct apm_user *as;
 154
 155         down_read(&user_list_lock);
 156
 157         list_for_each_entry(as, &apm_user_list, list)
 158                 if (as != sender && as->reader)
 159                         queue_event_one_user(as, event);
 160
 161         up_read(&user_list_lock);
 162         wake_up_interruptible(&apm_waitqueue);
 163 }
 164
 165 /**
 166  * apm_queue_event - queue an APM event for kapmd
 167  * @event: APM event
 168  *
 169  * Queue an APM event for kapmd to process and ultimately take the
 170  * appropriate action.  Only a subset of events are handled:
 171  *   %APM_LOW_BATTERY
 172  *   %APM_POWER_STATUS_CHANGE
 173  *   %APM_USER_SUSPEND
 174  *   %APM_SYS_SUSPEND
 175  *   %APM_CRITICAL_SUSPEND
 176  */
 177 void apm_queue_event(apm_event_t event)
 178 {
 179         spin_lock_irq(&kapmd_queue_lock);
 180         queue_add_event(&kapmd_queue, event);
 181         spin_unlock_irq(&kapmd_queue_lock);
 182
 183         wake_up_interruptible(&kapmd_wait);
 184 }
 185 EXPORT_SYMBOL(apm_queue_event);
 186
 187 static void apm_suspend(void)
 188 {
 189         struct apm_user *as;
 190         int err;
 191
 192         apm_suspended = 1;
 193         err = pm_suspend(PM_SUSPEND_MEM);
 194
 195         /*
 196          * Anyone on the APM queues will think we're still suspended.
 197          * Send a message so everyone knows we're now awake again.
 198          */
 199         queue_event(APM_NORMAL_RESUME, NULL);
 200
 201         /*
 202          * Finally, wake up anyone who is sleeping on the suspend.
 203          */
 204         down_read(&user_list_lock);
 205         list_for_each_entry(as, &apm_user_list, list) {
 206                 as->suspend_result = err;
 207                 as->suspend_state = SUSPEND_DONE;
 208         }
 209         up_read(&user_list_lock);
 210
 211         wake_up(&apm_suspend_waitqueue);
 212         apm_suspended = 0;
 213 }
 214
 215 static ssize_t apm_read(struct file *fp, char __user *buf,
 216                         size_t count, loff_t *ppos)
 217 {
 218         struct apm_user *as = fp->private_data;
 219         apm_event_t event;
 220         int i = count, ret = 0;
 221
 222         if (count < sizeof(apm_event_t))
 223                 return -EINVAL;
 224
 225         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 226                 return -EAGAIN;
 227
 228         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 229
 230         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 231                 event = queue_get_event(&as->queue);
 232
 233                 ret = -EFAULT;
 234                 if (copy_to_user(buf, &event, sizeof(event)))
 235                         break;
 236
 237                 if (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)
 238                         as->suspend_state = SUSPEND_READ;
 239
 240                 buf += sizeof(event);
 241                 i -= sizeof(event);
 242         }
 243
 244         if (i < count)
 245                 ret = count - i;
 246
 247         return ret;
 248 }
 249
 250 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 251 {
 252         struct apm_user *as = fp->private_data;
 253
 254         poll_wait(fp, &apm_waitqueue, wait);
 255         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 256 }
 257
 258 /*
 259  * apm_ioctl - handle APM ioctl
 260  *
 261  * APM_IOC_SUSPEND
 262  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 263  *     - initiate a suspend
 264  *     - acknowledge a suspend read from /dev/apm_bios.
 265  *   Only when everyone who has opened /dev/apm_bios with write permission
 266  *   has acknowledge does the actual suspend happen.
 267  */
 268 static int
 269 apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
 270 {
 271         struct apm_user *as = filp->private_data;
 272         unsigned long flags;
 273         int err = -EINVAL;
 274
 275         if (!as->suser || !as->writer)
 276                 return -EPERM;
 277
 278         switch (cmd) {
 279         case APM_IOC_SUSPEND:
 280                 as->suspend_result = -EINTR;
 281
 282                 if (as->suspend_state == SUSPEND_READ) {
 283                         /*
 284                          * If we read a suspend command from /dev/apm_bios,
 285                          * then the corresponding APM_IOC_SUSPEND ioctl is
 286                          * interpreted as an acknowledge.
 287                          */
 288                         as->suspend_state = SUSPEND_ACKED;
 289                         suspends_pending--;
 290                 } else {
 291                         /*
 292                          * Otherwise it is a request to suspend the system.
 293                          * Queue an event for all readers, and expect an
 294                          * acknowledge from all writers who haven't already
 295                          * acknowledged.
 296                          */
 297                         queue_event(APM_USER_SUSPEND, as);
 298                 }
 299
 300                 /*
 301                  * If there are no further acknowledges required, suspend
 302                  * the system.
 303                  */
 304                 if (suspends_pending == 0)
 305                         apm_suspend();
 306
 307                 /*
 308                  * Wait for the suspend/resume to complete.  If there are
 309                  * pending acknowledges, we wait here for them.
 310                  *
 311                  * Note that we need to ensure that the PM subsystem does
 312                  * not kick us out of the wait when it suspends the threads.
 313                  */
 314                 flags = current->flags;
 315                 current->flags |= PF_NOFREEZE;
 316
 317                 /*
 318                  * Note: do not allow a thread which is acking the suspend
 319                  * to escape until the resume is complete.
 320                  */
 321                 if (as->suspend_state == SUSPEND_ACKED)
 322                         wait_event(apm_suspend_waitqueue,
 323                                          as->suspend_state == SUSPEND_DONE);
 324                 else
 325                         wait_event_interruptible(apm_suspend_waitqueue,
 326                                          as->suspend_state == SUSPEND_DONE);
 327
 328                 current->flags = flags;
 329                 err = as->suspend_result;
 330                 as->suspend_state = SUSPEND_NONE;
 331                 break;
 332         }
 333
 334         return err;
 335 }
 336
 337 static int apm_release(struct inode * inode, struct file * filp)
 338 {
 339         struct apm_user *as = filp->private_data;
 340         filp->private_data = NULL;
 341
 342         down_write(&user_list_lock);
 343         list_del(&as->list);
 344         up_write(&user_list_lock);
 345
 346         /*
 347          * We are now unhooked from the chain.  As far as new
 348          * events are concerned, we no longer exist.  However, we
 349          * need to balance suspends_pending, which means the
 350          * possibility of sleeping.
 351          */
 352         if (as->suspend_state != SUSPEND_NONE) {
 353                 suspends_pending -= 1;
 354                 if (suspends_pending == 0)
 355                         apm_suspend();
 356         }
 357
 358         kfree(as);
 359         return 0;
 360 }
 361
 362 static int apm_open(struct inode * inode, struct file * filp)
 363 {
 364         struct apm_user *as;
 365
 366         as = kzalloc(sizeof(*as), GFP_KERNEL);
 367         if (as) {
 368                 /*
 369                  * XXX - this is a tiny bit broken, when we consider BSD
 370                  * process accounting. If the device is opened by root, we
 371                  * instantly flag that we used superuser privs. Who knows,
 372                  * we might close the device immediately without doing a
 373                  * privileged operation -- cevans
 374                  */
 375                 as->suser = capable(CAP_SYS_ADMIN);
 376                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 377                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 378
 379                 down_write(&user_list_lock);
 380                 list_add(&as->list, &apm_user_list);
 381                 up_write(&user_list_lock);
 382
 383                 filp->private_data = as;
 384         }
 385
 386         return as ? 0 : -ENOMEM;
 387 }
 388
 389 static struct file_operations apm_bios_fops = {
 390         .owner          = THIS_MODULE,
 391         .read           = apm_read,
 392         .poll           = apm_poll,
 393         .ioctl          = apm_ioctl,
 394         .open           = apm_open,
 395         .release        = apm_release,
 396 };
 397
 398 static struct miscdevice apm_device = {
 399         .minor          = APM_MINOR_DEV,
 400         .name           = "apm_bios",
 401         .fops           = &apm_bios_fops
 402 };
 403
 404
 405 #ifdef CONFIG_PROC_FS
 406 /*
 407  * Arguments, with symbols from linux/apm_bios.h.
 408  *
 409  *   0) Linux driver version (this will change if format changes)
 410  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 411  *   2) APM flags from APM Installation Check (0x00):
 412  *      bit 0: APM_16_BIT_SUPPORT
 413  *      bit 1: APM_32_BIT_SUPPORT
 414  *      bit 2: APM_IDLE_SLOWS_CLOCK
 415  *      bit 3: APM_BIOS_DISABLED
 416  *      bit 4: APM_BIOS_DISENGAGED
 417  *   3) AC line status
 418  *      0x00: Off-line
 419  *      0x01: On-line
 420  *      0x02: On backup power (BIOS >= 1.1 only)
 421  *      0xff: Unknown
 422  *   4) Battery status
 423  *      0x00: High
 424  *      0x01: Low
 425  *      0x02: Critical
 426  *      0x03: Charging
 427  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 428  *      0xff: Unknown
 429  *   5) Battery flag
 430  *      bit 0: High
 431  *      bit 1: Low
 432  *      bit 2: Critical
 433  *      bit 3: Charging
 434  *      bit 7: No system battery
 435  *      0xff: Unknown
 436  *   6) Remaining battery life (percentage of charge):
 437  *      0-100: valid
 438  *      -1: Unknown
 439  *   7) Remaining battery life (time units):
 440  *      Number of remaining minutes or seconds
 441  *      -1: Unknown
 442  *   8) min = minutes; sec = seconds
 443  */
 444 static int apm_read_proc(char *buf, char **start, off_t fpos, int length)
 445 {
 446         if (likely(apm_get_info))
 447                 return apm_get_info(buf, start, fpos, length);
 448
 449         return -EINVAL;
 450 }
 451 #endif
 452
 453 static int kapmd(void *arg)
 454 {
 455         daemonize("kapmd");
 456         current->flags |= PF_NOFREEZE;
 457
 458         do {
 459                 apm_event_t event;
 460
 461                 wait_event_interruptible(kapmd_wait,
 462                                 !queue_empty(&kapmd_queue) || !pm_active);
 463
 464                 if (!pm_active)
 465                         break;
 466
 467                 spin_lock_irq(&kapmd_queue_lock);
 468                 event = 0;
 469                 if (!queue_empty(&kapmd_queue))
 470                         event = queue_get_event(&kapmd_queue);
 471                 spin_unlock_irq(&kapmd_queue_lock);
 472
 473                 switch (event) {
 474                 case 0:
 475                         break;
 476
 477                 case APM_LOW_BATTERY:
 478                 case APM_POWER_STATUS_CHANGE:
 479                         queue_event(event, NULL);
 480                         break;
 481
 482                 case APM_USER_SUSPEND:
 483                 case APM_SYS_SUSPEND:
 484                         queue_event(event, NULL);
 485                         if (suspends_pending == 0)
 486                                 apm_suspend();
 487                         break;
 488
 489                 case APM_CRITICAL_SUSPEND:
 490                         apm_suspend();
 491                         break;
 492                 }
 493         } while (1);
 494
 495         complete_and_exit(&kapmd_exit, 0);
 496 }
 497
 498 static int __init apm_init(void)
 499 {
 500         int ret;
 501
 502         pm_active = 1;
 503
 504         ret = kernel_thread(kapmd, NULL, CLONE_KERNEL);
 505         if (unlikely(ret < 0)) {
 506                 pm_active = 0;
 507                 return ret;
 508         }
 509
 510         create_proc_info_entry("apm", 0, NULL, apm_read_proc);
 511
 512         ret = misc_register(&apm_device);
 513         if (unlikely(ret != 0)) {
 514                 remove_proc_entry("apm", NULL);
 515
 516                 pm_active = 0;
 517                 wake_up(&kapmd_wait);
 518                 wait_for_completion(&kapmd_exit);
 519         }
 520
 521         return ret;
 522 }
 523
 524 static void __exit apm_exit(void)
 525 {
 526         misc_deregister(&apm_device);
 527         remove_proc_entry("apm", NULL);
 528
 529         pm_active = 0;
 530         wake_up(&kapmd_wait);
 531         wait_for_completion(&kapmd_exit);
 532 }
 533
 534 module_init(apm_init);
 535 module_exit(apm_exit);
 536
 537 MODULE_AUTHOR("Stephen Rothwell, Andriy Skulysh");
 538 MODULE_DESCRIPTION("Advanced Power Management");
 539 MODULE_LICENSE("GPL");