drivers/char/apm-emulation.c

   1 /*
   2  * bios-less APM driver for ARM Linux
   3  *  Jamey Hicks <jamey@crl.dec.com>
   4  *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
   5  *
   6  * APM 1.2 Reference:
   7  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
   8  *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
   9  *
  10  * This document is available from Microsoft at:
  11  *    http://www.microsoft.com/whdc/archive/amp_12.mspx
  12  */
  13 #include <linux/module.h>
  14 #include <linux/poll.h>
  15 #include <linux/slab.h>
  16 #include <linux/mutex.h>
  17 #include <linux/proc_fs.h>
  18 #include <linux/seq_file.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/apm_bios.h>
  21 #include <linux/capability.h>
  22 #include <linux/sched.h>
  23 #include <linux/suspend.h>
  24 #include <linux/apm-emulation.h>
  25 #include <linux/freezer.h>
  26 #include <linux/device.h>
  27 #include <linux/kernel.h>
  28 #include <linux/list.h>
  29 #include <linux/init.h>
  30 #include <linux/completion.h>
  31 #include <linux/kthread.h>
  32 #include <linux/delay.h>
  33
  34
  35 /*
  36  * The apm_bios device is one of the misc char devices.
  37  * This is its minor number.
  38  */
  39 #define APM_MINOR_DEV   134
  40
  41 /*
  42  * One option can be changed at boot time as follows:
  43  *      apm=on/off                      enable/disable APM
  44  */
  45
  46 /*
  47  * Maximum number of events stored
  48  */
  49 #define APM_MAX_EVENTS          16
  50
  51 struct apm_queue {
  52         unsigned int            event_head;
  53         unsigned int            event_tail;
  54         apm_event_t             events[APM_MAX_EVENTS];
  55 };
  56
  57 /*
  58  * thread states (for threads using a writable /dev/apm_bios fd):
  59  *
  60  * SUSPEND_NONE:        nothing happening
  61  * SUSPEND_PENDING:     suspend event queued for thread and pending to be read
  62  * SUSPEND_READ:        suspend event read, pending acknowledgement
  63  * SUSPEND_ACKED:       acknowledgement received from thread (via ioctl),
  64  *                      waiting for resume
  65  * SUSPEND_ACKTO:       acknowledgement timeout
  66  * SUSPEND_DONE:        thread had acked suspend and is now notified of
  67  *                      resume
  68  *
  69  * SUSPEND_WAIT:        this thread invoked suspend and is waiting for resume
  70  *
  71  * A thread migrates in one of three paths:
  72  *      NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
  73  *                                  -6-> ACKTO -7-> NONE
  74  *      NONE -8-> WAIT -9-> NONE
  75  *
  76  * While in PENDING or READ, the thread is accounted for in the
  77  * suspend_acks_pending counter.
  78  *
  79  * The transitions are invoked as follows:
  80  *      1: suspend event is signalled from the core PM code
  81  *      2: the suspend event is read from the fd by the userspace thread
  82  *      3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
  83  *      4: core PM code signals that we have resumed
  84  *      5: APM_IOC_SUSPEND ioctl returns
  85  *
  86  *      6: the notifier invoked from the core PM code timed out waiting
  87  *         for all relevant threds to enter ACKED state and puts those
  88  *         that haven't into ACKTO
  89  *      7: those threads issue APM_IOC_SUSPEND ioctl too late,
  90  *         get an error
  91  *
  92  *      8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
  93  *         ioctl code invokes pm_suspend()
  94  *      9: pm_suspend() returns indicating resume
  95  */
  96 enum apm_suspend_state {
  97         SUSPEND_NONE,
  98         SUSPEND_PENDING,
  99         SUSPEND_READ,
 100         SUSPEND_ACKED,
 101         SUSPEND_ACKTO,
 102         SUSPEND_WAIT,
 103         SUSPEND_DONE,
 104 };
 105
 106 /*
 107  * The per-file APM data
 108  */
 109 struct apm_user {
 110         struct list_head        list;
 111
 112         unsigned int            suser: 1;
 113         unsigned int            writer: 1;
 114         unsigned int            reader: 1;
 115
 116         int                     suspend_result;
 117         enum apm_suspend_state  suspend_state;
 118
 119         struct apm_queue        queue;
 120 };
 121
 122 /*
 123  * Local variables
 124  */
 125 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
 126 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
 127 static int apm_disabled;
 128 static struct task_struct *kapmd_tsk;
 129
 130 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
 131 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
 132
 133 /*
 134  * This is a list of everyone who has opened /dev/apm_bios
 135  */
 136 static DECLARE_RWSEM(user_list_lock);
 137 static LIST_HEAD(apm_user_list);
 138
 139 /*
 140  * kapmd info.  kapmd provides us a process context to handle
 141  * "APM" events within - specifically necessary if we're going
 142  * to be suspending the system.
 143  */
 144 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 145 static DEFINE_SPINLOCK(kapmd_queue_lock);
 146 static struct apm_queue kapmd_queue;
 147
 148 static DEFINE_MUTEX(state_lock);
 149
 150 static const char driver_version[] = "1.13";    /* no spaces */
 151
 152
 153
 154 /*
 155  * Compatibility cruft until the IPAQ people move over to the new
 156  * interface.
 157  */
 158 static void __apm_get_power_status(struct apm_power_info *info)
 159 {
 160 }
 161
 162 /*
 163  * This allows machines to provide their own "apm get power status" function.
 164  */
 165 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 166 EXPORT_SYMBOL(apm_get_power_status);
 167
 168
 169 /*
 170  * APM event queue management.
 171  */
 172 static inline int queue_empty(struct apm_queue *q)
 173 {
 174         return q->event_head == q->event_tail;
 175 }
 176
 177 static inline apm_event_t queue_get_event(struct apm_queue *q)
 178 {
 179         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 180         return q->events[q->event_tail];
 181 }
 182
 183 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 184 {
 185         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 186         if (q->event_head == q->event_tail) {
 187                 static int notified;
 188
 189                 if (notified++ == 0)
 190                     printk(KERN_ERR "apm: an event queue overflowed\n");
 191                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 192         }
 193         q->events[q->event_head] = event;
 194 }
 195
 196 static void queue_event(apm_event_t event)
 197 {
 198         struct apm_user *as;
 199
 200         down_read(&user_list_lock);
 201         list_for_each_entry(as, &apm_user_list, list) {
 202                 if (as->reader)
 203                         queue_add_event(&as->queue, event);
 204         }
 205         up_read(&user_list_lock);
 206         wake_up_interruptible(&apm_waitqueue);
 207 }
 208
 209 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 210 {
 211         struct apm_user *as = fp->private_data;
 212         apm_event_t event;
 213         int i = count, ret = 0;
 214
 215         if (count < sizeof(apm_event_t))
 216                 return -EINVAL;
 217
 218         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 219                 return -EAGAIN;
 220
 221         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 222
 223         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 224                 event = queue_get_event(&as->queue);
 225
 226                 ret = -EFAULT;
 227                 if (copy_to_user(buf, &event, sizeof(event)))
 228                         break;
 229
 230                 mutex_lock(&state_lock);
 231                 if (as->suspend_state == SUSPEND_PENDING &&
 232                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
 233                         as->suspend_state = SUSPEND_READ;
 234                 mutex_unlock(&state_lock);
 235
 236                 buf += sizeof(event);
 237                 i -= sizeof(event);
 238         }
 239
 240         if (i < count)
 241                 ret = count - i;
 242
 243         return ret;
 244 }
 245
 246 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 247 {
 248         struct apm_user *as = fp->private_data;
 249
 250         poll_wait(fp, &apm_waitqueue, wait);
 251         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 252 }
 253
 254 /*
 255  * apm_ioctl - handle APM ioctl
 256  *
 257  * APM_IOC_SUSPEND
 258  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 259  *     - initiate a suspend
 260  *     - acknowledge a suspend read from /dev/apm_bios.
 261  *   Only when everyone who has opened /dev/apm_bios with write permission
 262  *   has acknowledge does the actual suspend happen.
 263  */
 264 static long
 265 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
 266 {
 267         struct apm_user *as = filp->private_data;
 268         int err = -EINVAL;
 269
 270         if (!as->suser || !as->writer)
 271                 return -EPERM;
 272
 273         switch (cmd) {
 274         case APM_IOC_SUSPEND:
 275                 mutex_lock(&state_lock);
 276
 277                 as->suspend_result = -EINTR;
 278
 279                 switch (as->suspend_state) {
 280                 case SUSPEND_READ:
 281                         /*
 282                          * If we read a suspend command from /dev/apm_bios,
 283                          * then the corresponding APM_IOC_SUSPEND ioctl is
 284                          * interpreted as an acknowledge.
 285                          */
 286                         as->suspend_state = SUSPEND_ACKED;
 287                         atomic_dec(&suspend_acks_pending);
 288                         mutex_unlock(&state_lock);
 289
 290                         /*
 291                          * suspend_acks_pending changed, the notifier needs to
 292                          * be woken up for this
 293                          */
 294                         wake_up(&apm_suspend_waitqueue);
 295
 296                         /*
 297                          * Wait for the suspend/resume to complete.  If there
 298                          * are pending acknowledges, we wait here for them.
 299                          * wait_event_freezable() is interruptible and pending
 300                          * signal can cause busy looping.  We aren't doing
 301                          * anything critical, chill a bit on each iteration.
 302                          */
 303                         while (wait_event_freezable(apm_suspend_waitqueue,
 304                                         as->suspend_state != SUSPEND_ACKED))
 305                                 msleep(10);
 306                         break;
 307                 case SUSPEND_ACKTO:
 308                         as->suspend_result = -ETIMEDOUT;
 309                         mutex_unlock(&state_lock);
 310                         break;
 311                 default:
 312                         as->suspend_state = SUSPEND_WAIT;
 313                         mutex_unlock(&state_lock);
 314
 315                         /*
 316                          * Otherwise it is a request to suspend the system.
 317                          * Just invoke pm_suspend(), we'll handle it from
 318                          * there via the notifier.
 319                          */
 320                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
 321                 }
 322
 323                 mutex_lock(&state_lock);
 324                 err = as->suspend_result;
 325                 as->suspend_state = SUSPEND_NONE;
 326                 mutex_unlock(&state_lock);
 327                 break;
 328         }
 329
 330         return err;
 331 }
 332
 333 static int apm_release(struct inode * inode, struct file * filp)
 334 {
 335         struct apm_user *as = filp->private_data;
 336
 337         filp->private_data = NULL;
 338
 339         down_write(&user_list_lock);
 340         list_del(&as->list);
 341         up_write(&user_list_lock);
 342
 343         /*
 344          * We are now unhooked from the chain.  As far as new
 345          * events are concerned, we no longer exist.
 346          */
 347         mutex_lock(&state_lock);
 348         if (as->suspend_state == SUSPEND_PENDING ||
 349             as->suspend_state == SUSPEND_READ)
 350                 atomic_dec(&suspend_acks_pending);
 351         mutex_unlock(&state_lock);
 352
 353         wake_up(&apm_suspend_waitqueue);
 354
 355         kfree(as);
 356         return 0;
 357 }
 358
 359 static int apm_open(struct inode * inode, struct file * filp)
 360 {
 361         struct apm_user *as;
 362
 363         as = kzalloc(sizeof(*as), GFP_KERNEL);
 364         if (as) {
 365                 /*
 366                  * XXX - this is a tiny bit broken, when we consider BSD
 367                  * process accounting. If the device is opened by root, we
 368                  * instantly flag that we used superuser privs. Who knows,
 369                  * we might close the device immediately without doing a
 370                  * privileged operation -- cevans
 371                  */
 372                 as->suser = capable(CAP_SYS_ADMIN);
 373                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 374                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 375
 376                 down_write(&user_list_lock);
 377                 list_add(&as->list, &apm_user_list);
 378                 up_write(&user_list_lock);
 379
 380                 filp->private_data = as;
 381         }
 382
 383         return as ? 0 : -ENOMEM;
 384 }
 385
 386 static const struct file_operations apm_bios_fops = {
 387         .owner          = THIS_MODULE,
 388         .read           = apm_read,
 389         .poll           = apm_poll,
 390         .unlocked_ioctl = apm_ioctl,
 391         .open           = apm_open,
 392         .release        = apm_release,
 393         .llseek         = noop_llseek,
 394 };
 395
 396 static struct miscdevice apm_device = {
 397         .minor          = APM_MINOR_DEV,
 398         .name           = "apm_bios",
 399         .fops           = &apm_bios_fops
 400 };
 401
 402
 403 #ifdef CONFIG_PROC_FS
 404 /*
 405  * Arguments, with symbols from linux/apm_bios.h.
 406  *
 407  *   0) Linux driver version (this will change if format changes)
 408  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 409  *   2) APM flags from APM Installation Check (0x00):
 410  *      bit 0: APM_16_BIT_SUPPORT
 411  *      bit 1: APM_32_BIT_SUPPORT
 412  *      bit 2: APM_IDLE_SLOWS_CLOCK
 413  *      bit 3: APM_BIOS_DISABLED
 414  *      bit 4: APM_BIOS_DISENGAGED
 415  *   3) AC line status
 416  *      0x00: Off-line
 417  *      0x01: On-line
 418  *      0x02: On backup power (BIOS >= 1.1 only)
 419  *      0xff: Unknown
 420  *   4) Battery status
 421  *      0x00: High
 422  *      0x01: Low
 423  *      0x02: Critical
 424  *      0x03: Charging
 425  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 426  *      0xff: Unknown
 427  *   5) Battery flag
 428  *      bit 0: High
 429  *      bit 1: Low
 430  *      bit 2: Critical
 431  *      bit 3: Charging
 432  *      bit 7: No system battery
 433  *      0xff: Unknown
 434  *   6) Remaining battery life (percentage of charge):
 435  *      0-100: valid
 436  *      -1: Unknown
 437  *   7) Remaining battery life (time units):
 438  *      Number of remaining minutes or seconds
 439  *      -1: Unknown
 440  *   8) min = minutes; sec = seconds
 441  */
 442 static int proc_apm_show(struct seq_file *m, void *v)
 443 {
 444         struct apm_power_info info;
 445         char *units;
 446
 447         info.ac_line_status = 0xff;
 448         info.battery_status = 0xff;
 449         info.battery_flag   = 0xff;
 450         info.battery_life   = -1;
 451         info.time           = -1;
 452         info.units          = -1;
 453
 454         if (apm_get_power_status)
 455                 apm_get_power_status(&info);
 456
 457         switch (info.units) {
 458         default:        units = "?";    break;
 459         case 0:         units = "min";  break;
 460         case 1:         units = "sec";  break;
 461         }
 462
 463         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 464                      driver_version, APM_32_BIT_SUPPORT,
 465                      info.ac_line_status, info.battery_status,
 466                      info.battery_flag, info.battery_life,
 467                      info.time, units);
 468
 469         return 0;
 470 }
 471
 472 static int proc_apm_open(struct inode *inode, struct file *file)
 473 {
 474         return single_open(file, proc_apm_show, NULL);
 475 }
 476
 477 static const struct file_operations apm_proc_fops = {
 478         .owner          = THIS_MODULE,
 479         .open           = proc_apm_open,
 480         .read           = seq_read,
 481         .llseek         = seq_lseek,
 482         .release        = single_release,
 483 };
 484 #endif
 485
 486 static int kapmd(void *arg)
 487 {
 488         do {
 489                 apm_event_t event;
 490
 491                 wait_event_interruptible(kapmd_wait,
 492                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
 493
 494                 if (kthread_should_stop())
 495                         break;
 496
 497                 spin_lock_irq(&kapmd_queue_lock);
 498                 event = 0;
 499                 if (!queue_empty(&kapmd_queue))
 500                         event = queue_get_event(&kapmd_queue);
 501                 spin_unlock_irq(&kapmd_queue_lock);
 502
 503                 switch (event) {
 504                 case 0:
 505                         break;
 506
 507                 case APM_LOW_BATTERY:
 508                 case APM_POWER_STATUS_CHANGE:
 509                         queue_event(event);
 510                         break;
 511
 512                 case APM_USER_SUSPEND:
 513                 case APM_SYS_SUSPEND:
 514                         pm_suspend(PM_SUSPEND_MEM);
 515                         break;
 516
 517                 case APM_CRITICAL_SUSPEND:
 518                         atomic_inc(&userspace_notification_inhibit);
 519                         pm_suspend(PM_SUSPEND_MEM);
 520                         atomic_dec(&userspace_notification_inhibit);
 521                         break;
 522                 }
 523         } while (1);
 524
 525         return 0;
 526 }
 527
 528 static int apm_suspend_notifier(struct notifier_block *nb,
 529                                 unsigned long event,
 530                                 void *dummy)
 531 {
 532         struct apm_user *as;
 533         int err;
 534
 535         /* short-cut emergency suspends */
 536         if (atomic_read(&userspace_notification_inhibit))
 537                 return NOTIFY_DONE;
 538
 539         switch (event) {
 540         case PM_SUSPEND_PREPARE:
 541                 /*
 542                  * Queue an event to all "writer" users that we want
 543                  * to suspend and need their ack.
 544                  */
 545                 mutex_lock(&state_lock);
 546                 down_read(&user_list_lock);
 547
 548                 list_for_each_entry(as, &apm_user_list, list) {
 549                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
 550                             as->writer && as->suser) {
 551                                 as->suspend_state = SUSPEND_PENDING;
 552                                 atomic_inc(&suspend_acks_pending);
 553                                 queue_add_event(&as->queue, APM_USER_SUSPEND);
 554                         }
 555                 }
 556
 557                 up_read(&user_list_lock);
 558                 mutex_unlock(&state_lock);
 559                 wake_up_interruptible(&apm_waitqueue);
 560
 561                 /*
 562                  * Wait for the the suspend_acks_pending variable to drop to
 563                  * zero, meaning everybody acked the suspend event (or the
 564                  * process was killed.)
 565                  *
 566                  * If the app won't answer within a short while we assume it
 567                  * locked up and ignore it.
 568                  */
 569                 err = wait_event_interruptible_timeout(
 570                         apm_suspend_waitqueue,
 571                         atomic_read(&suspend_acks_pending) == 0,
 572                         5*HZ);
 573
 574                 /* timed out */
 575                 if (err == 0) {
 576                         /*
 577                          * Move anybody who timed out to "ack timeout" state.
 578                          *
 579                          * We could time out and the userspace does the ACK
 580                          * right after we time out but before we enter the
 581                          * locked section here, but that's fine.
 582                          */
 583                         mutex_lock(&state_lock);
 584                         down_read(&user_list_lock);
 585                         list_for_each_entry(as, &apm_user_list, list) {
 586                                 if (as->suspend_state == SUSPEND_PENDING ||
 587                                     as->suspend_state == SUSPEND_READ) {
 588                                         as->suspend_state = SUSPEND_ACKTO;
 589                                         atomic_dec(&suspend_acks_pending);
 590                                 }
 591                         }
 592                         up_read(&user_list_lock);
 593                         mutex_unlock(&state_lock);
 594                 }
 595
 596                 /* let suspend proceed */
 597                 if (err >= 0)
 598                         return NOTIFY_OK;
 599
 600                 /* interrupted by signal */
 601                 return notifier_from_errno(err);
 602
 603         case PM_POST_SUSPEND:
 604                 /*
 605                  * Anyone on the APM queues will think we're still suspended.
 606                  * Send a message so everyone knows we're now awake again.
 607                  */
 608                 queue_event(APM_NORMAL_RESUME);
 609
 610                 /*
 611                  * Finally, wake up anyone who is sleeping on the suspend.
 612                  */
 613                 mutex_lock(&state_lock);
 614                 down_read(&user_list_lock);
 615                 list_for_each_entry(as, &apm_user_list, list) {
 616                         if (as->suspend_state == SUSPEND_ACKED) {
 617                                 /*
 618                                  * TODO: maybe grab error code, needs core
 619                                  * changes to push the error to the notifier
 620                                  * chain (could use the second parameter if
 621                                  * implemented)
 622                                  */
 623                                 as->suspend_result = 0;
 624                                 as->suspend_state = SUSPEND_DONE;
 625                         }
 626                 }
 627                 up_read(&user_list_lock);
 628                 mutex_unlock(&state_lock);
 629
 630                 wake_up(&apm_suspend_waitqueue);
 631                 return NOTIFY_OK;
 632
 633         default:
 634                 return NOTIFY_DONE;
 635         }
 636 }
 637
 638 static struct notifier_block apm_notif_block = {
 639         .notifier_call = apm_suspend_notifier,
 640 };
 641
 642 static int __init apm_init(void)
 643 {
 644         int ret;
 645
 646         if (apm_disabled) {
 647                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 648                 return -ENODEV;
 649         }
 650
 651         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
 652         if (IS_ERR(kapmd_tsk)) {
 653                 ret = PTR_ERR(kapmd_tsk);
 654                 kapmd_tsk = NULL;
 655                 goto out;
 656         }
 657         wake_up_process(kapmd_tsk);
 658
 659 #ifdef CONFIG_PROC_FS
 660         proc_create("apm", 0, NULL, &apm_proc_fops);
 661 #endif
 662
 663         ret = misc_register(&apm_device);
 664         if (ret)
 665                 goto out_stop;
 666
 667         ret = register_pm_notifier(&apm_notif_block);
 668         if (ret)
 669                 goto out_unregister;
 670
 671         return 0;
 672
 673  out_unregister:
 674         misc_deregister(&apm_device);
 675  out_stop:
 676         remove_proc_entry("apm", NULL);
 677         kthread_stop(kapmd_tsk);
 678  out:
 679         return ret;
 680 }
 681
 682 static void __exit apm_exit(void)
 683 {
 684         unregister_pm_notifier(&apm_notif_block);
 685         misc_deregister(&apm_device);
 686         remove_proc_entry("apm", NULL);
 687
 688         kthread_stop(kapmd_tsk);
 689 }
 690
 691 module_init(apm_init);
 692 module_exit(apm_exit);
 693
 694 MODULE_AUTHOR("Stephen Rothwell");
 695 MODULE_DESCRIPTION("Advanced Power Management");
 696 MODULE_LICENSE("GPL");
 697
 698 #ifndef MODULE
 699 static int __init apm_setup(char *str)
 700 {
 701         while ((str != NULL) && (*str != '\0')) {
 702                 if (strncmp(str, "off", 3) == 0)
 703                         apm_disabled = 1;
 704                 if (strncmp(str, "on", 2) == 0)
 705                         apm_disabled = 0;
 706                 str = strchr(str, ',');
 707                 if (str != NULL)
 708                         str += strspn(str, ", \t");
 709         }
 710         return 1;
 711 }
 712
 713 __setup("apm=", apm_setup);
 714 #endif
 715
 716 /**
 717  * apm_queue_event - queue an APM event for kapmd
 718  * @event: APM event
 719  *
 720  * Queue an APM event for kapmd to process and ultimately take the
 721  * appropriate action.  Only a subset of events are handled:
 722  *   %APM_LOW_BATTERY
 723  *   %APM_POWER_STATUS_CHANGE
 724  *   %APM_USER_SUSPEND
 725  *   %APM_SYS_SUSPEND
 726  *   %APM_CRITICAL_SUSPEND
 727  */
 728 void apm_queue_event(apm_event_t event)
 729 {
 730         unsigned long flags;
 731
 732         spin_lock_irqsave(&kapmd_queue_lock, flags);
 733         queue_add_event(&kapmd_queue, event);
 734         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 735
 736         wake_up_interruptible(&kapmd_wait);
 737 }
 738 EXPORT_SYMBOL(apm_queue_event);