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 #include <asm/system.h>
  35
  36 /*
  37  * The apm_bios device is one of the misc char devices.
  38  * This is its minor number.
  39  */
  40 #define APM_MINOR_DEV   134
  41
  42 /*
  43  * See Documentation/Config.help for the configuration options.
  44  *
  45  * Various options can be changed at boot time as follows:
  46  * (We allow underscores for compatibility with the modules code)
  47  *      apm=on/off                      enable/disable APM
  48  */
  49
  50 /*
  51  * Maximum number of events stored
  52  */
  53 #define APM_MAX_EVENTS          16
  54
  55 struct apm_queue {
  56         unsigned int            event_head;
  57         unsigned int            event_tail;
  58         apm_event_t             events[APM_MAX_EVENTS];
  59 };
  60
  61 /*
  62  * thread states (for threads using a writable /dev/apm_bios fd):
  63  *
  64  * SUSPEND_NONE:        nothing happening
  65  * SUSPEND_PENDING:     suspend event queued for thread and pending to be read
  66  * SUSPEND_READ:        suspend event read, pending acknowledgement
  67  * SUSPEND_ACKED:       acknowledgement received from thread (via ioctl),
  68  *                      waiting for resume
  69  * SUSPEND_ACKTO:       acknowledgement timeout
  70  * SUSPEND_DONE:        thread had acked suspend and is now notified of
  71  *                      resume
  72  *
  73  * SUSPEND_WAIT:        this thread invoked suspend and is waiting for resume
  74  *
  75  * A thread migrates in one of three paths:
  76  *      NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
  77  *                                  -6-> ACKTO -7-> NONE
  78  *      NONE -8-> WAIT -9-> NONE
  79  *
  80  * While in PENDING or READ, the thread is accounted for in the
  81  * suspend_acks_pending counter.
  82  *
  83  * The transitions are invoked as follows:
  84  *      1: suspend event is signalled from the core PM code
  85  *      2: the suspend event is read from the fd by the userspace thread
  86  *      3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
  87  *      4: core PM code signals that we have resumed
  88  *      5: APM_IOC_SUSPEND ioctl returns
  89  *
  90  *      6: the notifier invoked from the core PM code timed out waiting
  91  *         for all relevant threds to enter ACKED state and puts those
  92  *         that haven't into ACKTO
  93  *      7: those threads issue APM_IOC_SUSPEND ioctl too late,
  94  *         get an error
  95  *
  96  *      8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
  97  *         ioctl code invokes pm_suspend()
  98  *      9: pm_suspend() returns indicating resume
  99  */
 100 enum apm_suspend_state {
 101         SUSPEND_NONE,
 102         SUSPEND_PENDING,
 103         SUSPEND_READ,
 104         SUSPEND_ACKED,
 105         SUSPEND_ACKTO,
 106         SUSPEND_WAIT,
 107         SUSPEND_DONE,
 108 };
 109
 110 /*
 111  * The per-file APM data
 112  */
 113 struct apm_user {
 114         struct list_head        list;
 115
 116         unsigned int            suser: 1;
 117         unsigned int            writer: 1;
 118         unsigned int            reader: 1;
 119
 120         int                     suspend_result;
 121         enum apm_suspend_state  suspend_state;
 122
 123         struct apm_queue        queue;
 124 };
 125
 126 /*
 127  * Local variables
 128  */
 129 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
 130 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
 131 static int apm_disabled;
 132 static struct task_struct *kapmd_tsk;
 133
 134 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
 135 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
 136
 137 /*
 138  * This is a list of everyone who has opened /dev/apm_bios
 139  */
 140 static DECLARE_RWSEM(user_list_lock);
 141 static LIST_HEAD(apm_user_list);
 142
 143 /*
 144  * kapmd info.  kapmd provides us a process context to handle
 145  * "APM" events within - specifically necessary if we're going
 146  * to be suspending the system.
 147  */
 148 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 149 static DEFINE_SPINLOCK(kapmd_queue_lock);
 150 static struct apm_queue kapmd_queue;
 151
 152 static DEFINE_MUTEX(state_lock);
 153
 154 static const char driver_version[] = "1.13";    /* no spaces */
 155
 156
 157
 158 /*
 159  * Compatibility cruft until the IPAQ people move over to the new
 160  * interface.
 161  */
 162 static void __apm_get_power_status(struct apm_power_info *info)
 163 {
 164 }
 165
 166 /*
 167  * This allows machines to provide their own "apm get power status" function.
 168  */
 169 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 170 EXPORT_SYMBOL(apm_get_power_status);
 171
 172
 173 /*
 174  * APM event queue management.
 175  */
 176 static inline int queue_empty(struct apm_queue *q)
 177 {
 178         return q->event_head == q->event_tail;
 179 }
 180
 181 static inline apm_event_t queue_get_event(struct apm_queue *q)
 182 {
 183         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 184         return q->events[q->event_tail];
 185 }
 186
 187 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 188 {
 189         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 190         if (q->event_head == q->event_tail) {
 191                 static int notified;
 192
 193                 if (notified++ == 0)
 194                     printk(KERN_ERR "apm: an event queue overflowed\n");
 195                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 196         }
 197         q->events[q->event_head] = event;
 198 }
 199
 200 static void queue_event(apm_event_t event)
 201 {
 202         struct apm_user *as;
 203
 204         down_read(&user_list_lock);
 205         list_for_each_entry(as, &apm_user_list, list) {
 206                 if (as->reader)
 207                         queue_add_event(&as->queue, event);
 208         }
 209         up_read(&user_list_lock);
 210         wake_up_interruptible(&apm_waitqueue);
 211 }
 212
 213 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 214 {
 215         struct apm_user *as = fp->private_data;
 216         apm_event_t event;
 217         int i = count, ret = 0;
 218
 219         if (count < sizeof(apm_event_t))
 220                 return -EINVAL;
 221
 222         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 223                 return -EAGAIN;
 224
 225         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 226
 227         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 228                 event = queue_get_event(&as->queue);
 229
 230                 ret = -EFAULT;
 231                 if (copy_to_user(buf, &event, sizeof(event)))
 232                         break;
 233
 234                 mutex_lock(&state_lock);
 235                 if (as->suspend_state == SUSPEND_PENDING &&
 236                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
 237                         as->suspend_state = SUSPEND_READ;
 238                 mutex_unlock(&state_lock);
 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 long
 269 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
 270 {
 271         struct apm_user *as = filp->private_data;
 272         int err = -EINVAL;
 273
 274         if (!as->suser || !as->writer)
 275                 return -EPERM;
 276
 277         switch (cmd) {
 278         case APM_IOC_SUSPEND:
 279                 mutex_lock(&state_lock);
 280
 281                 as->suspend_result = -EINTR;
 282
 283                 switch (as->suspend_state) {
 284                 case SUSPEND_READ:
 285                         /*
 286                          * If we read a suspend command from /dev/apm_bios,
 287                          * then the corresponding APM_IOC_SUSPEND ioctl is
 288                          * interpreted as an acknowledge.
 289                          */
 290                         as->suspend_state = SUSPEND_ACKED;
 291                         atomic_dec(&suspend_acks_pending);
 292                         mutex_unlock(&state_lock);
 293
 294                         /*
 295                          * suspend_acks_pending changed, the notifier needs to
 296                          * be woken up for this
 297                          */
 298                         wake_up(&apm_suspend_waitqueue);
 299
 300                         /*
 301                          * Wait for the suspend/resume to complete.  If there
 302                          * are pending acknowledges, we wait here for them.
 303                          */
 304                         freezer_do_not_count();
 305
 306                         wait_event(apm_suspend_waitqueue,
 307                                    as->suspend_state == SUSPEND_DONE);
 308
 309                         /*
 310                          * Since we are waiting until the suspend is done, the
 311                          * try_to_freeze() in freezer_count() will not trigger
 312                          */
 313                         freezer_count();
 314                         break;
 315                 case SUSPEND_ACKTO:
 316                         as->suspend_result = -ETIMEDOUT;
 317                         mutex_unlock(&state_lock);
 318                         break;
 319                 default:
 320                         as->suspend_state = SUSPEND_WAIT;
 321                         mutex_unlock(&state_lock);
 322
 323                         /*
 324                          * Otherwise it is a request to suspend the system.
 325                          * Just invoke pm_suspend(), we'll handle it from
 326                          * there via the notifier.
 327                          */
 328                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
 329                 }
 330
 331                 mutex_lock(&state_lock);
 332                 err = as->suspend_result;
 333                 as->suspend_state = SUSPEND_NONE;
 334                 mutex_unlock(&state_lock);
 335                 break;
 336         }
 337
 338         return err;
 339 }
 340
 341 static int apm_release(struct inode * inode, struct file * filp)
 342 {
 343         struct apm_user *as = filp->private_data;
 344
 345         filp->private_data = NULL;
 346
 347         down_write(&user_list_lock);
 348         list_del(&as->list);
 349         up_write(&user_list_lock);
 350
 351         /*
 352          * We are now unhooked from the chain.  As far as new
 353          * events are concerned, we no longer exist.
 354          */
 355         mutex_lock(&state_lock);
 356         if (as->suspend_state == SUSPEND_PENDING ||
 357             as->suspend_state == SUSPEND_READ)
 358                 atomic_dec(&suspend_acks_pending);
 359         mutex_unlock(&state_lock);
 360
 361         wake_up(&apm_suspend_waitqueue);
 362
 363         kfree(as);
 364         return 0;
 365 }
 366
 367 static int apm_open(struct inode * inode, struct file * filp)
 368 {
 369         struct apm_user *as;
 370
 371         as = kzalloc(sizeof(*as), GFP_KERNEL);
 372         if (as) {
 373                 /*
 374                  * XXX - this is a tiny bit broken, when we consider BSD
 375                  * process accounting. If the device is opened by root, we
 376                  * instantly flag that we used superuser privs. Who knows,
 377                  * we might close the device immediately without doing a
 378                  * privileged operation -- cevans
 379                  */
 380                 as->suser = capable(CAP_SYS_ADMIN);
 381                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 382                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 383
 384                 down_write(&user_list_lock);
 385                 list_add(&as->list, &apm_user_list);
 386                 up_write(&user_list_lock);
 387
 388                 filp->private_data = as;
 389         }
 390
 391         return as ? 0 : -ENOMEM;
 392 }
 393
 394 static const struct file_operations apm_bios_fops = {
 395         .owner          = THIS_MODULE,
 396         .read           = apm_read,
 397         .poll           = apm_poll,
 398         .unlocked_ioctl = apm_ioctl,
 399         .open           = apm_open,
 400         .release        = apm_release,
 401         .llseek         = noop_llseek,
 402 };
 403
 404 static struct miscdevice apm_device = {
 405         .minor          = APM_MINOR_DEV,
 406         .name           = "apm_bios",
 407         .fops           = &apm_bios_fops
 408 };
 409
 410
 411 #ifdef CONFIG_PROC_FS
 412 /*
 413  * Arguments, with symbols from linux/apm_bios.h.
 414  *
 415  *   0) Linux driver version (this will change if format changes)
 416  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 417  *   2) APM flags from APM Installation Check (0x00):
 418  *      bit 0: APM_16_BIT_SUPPORT
 419  *      bit 1: APM_32_BIT_SUPPORT
 420  *      bit 2: APM_IDLE_SLOWS_CLOCK
 421  *      bit 3: APM_BIOS_DISABLED
 422  *      bit 4: APM_BIOS_DISENGAGED
 423  *   3) AC line status
 424  *      0x00: Off-line
 425  *      0x01: On-line
 426  *      0x02: On backup power (BIOS >= 1.1 only)
 427  *      0xff: Unknown
 428  *   4) Battery status
 429  *      0x00: High
 430  *      0x01: Low
 431  *      0x02: Critical
 432  *      0x03: Charging
 433  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 434  *      0xff: Unknown
 435  *   5) Battery flag
 436  *      bit 0: High
 437  *      bit 1: Low
 438  *      bit 2: Critical
 439  *      bit 3: Charging
 440  *      bit 7: No system battery
 441  *      0xff: Unknown
 442  *   6) Remaining battery life (percentage of charge):
 443  *      0-100: valid
 444  *      -1: Unknown
 445  *   7) Remaining battery life (time units):
 446  *      Number of remaining minutes or seconds
 447  *      -1: Unknown
 448  *   8) min = minutes; sec = seconds
 449  */
 450 static int proc_apm_show(struct seq_file *m, void *v)
 451 {
 452         struct apm_power_info info;
 453         char *units;
 454
 455         info.ac_line_status = 0xff;
 456         info.battery_status = 0xff;
 457         info.battery_flag   = 0xff;
 458         info.battery_life   = -1;
 459         info.time           = -1;
 460         info.units          = -1;
 461
 462         if (apm_get_power_status)
 463                 apm_get_power_status(&info);
 464
 465         switch (info.units) {
 466         default:        units = "?";    break;
 467         case 0:         units = "min";  break;
 468         case 1:         units = "sec";  break;
 469         }
 470
 471         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 472                      driver_version, APM_32_BIT_SUPPORT,
 473                      info.ac_line_status, info.battery_status,
 474                      info.battery_flag, info.battery_life,
 475                      info.time, units);
 476
 477         return 0;
 478 }
 479
 480 static int proc_apm_open(struct inode *inode, struct file *file)
 481 {
 482         return single_open(file, proc_apm_show, NULL);
 483 }
 484
 485 static const struct file_operations apm_proc_fops = {
 486         .owner          = THIS_MODULE,
 487         .open           = proc_apm_open,
 488         .read           = seq_read,
 489         .llseek         = seq_lseek,
 490         .release        = single_release,
 491 };
 492 #endif
 493
 494 static int kapmd(void *arg)
 495 {
 496         do {
 497                 apm_event_t event;
 498
 499                 wait_event_interruptible(kapmd_wait,
 500                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
 501
 502                 if (kthread_should_stop())
 503                         break;
 504
 505                 spin_lock_irq(&kapmd_queue_lock);
 506                 event = 0;
 507                 if (!queue_empty(&kapmd_queue))
 508                         event = queue_get_event(&kapmd_queue);
 509                 spin_unlock_irq(&kapmd_queue_lock);
 510
 511                 switch (event) {
 512                 case 0:
 513                         break;
 514
 515                 case APM_LOW_BATTERY:
 516                 case APM_POWER_STATUS_CHANGE:
 517                         queue_event(event);
 518                         break;
 519
 520                 case APM_USER_SUSPEND:
 521                 case APM_SYS_SUSPEND:
 522                         pm_suspend(PM_SUSPEND_MEM);
 523                         break;
 524
 525                 case APM_CRITICAL_SUSPEND:
 526                         atomic_inc(&userspace_notification_inhibit);
 527                         pm_suspend(PM_SUSPEND_MEM);
 528                         atomic_dec(&userspace_notification_inhibit);
 529                         break;
 530                 }
 531         } while (1);
 532
 533         return 0;
 534 }
 535
 536 static int apm_suspend_notifier(struct notifier_block *nb,
 537                                 unsigned long event,
 538                                 void *dummy)
 539 {
 540         struct apm_user *as;
 541         int err;
 542
 543         /* short-cut emergency suspends */
 544         if (atomic_read(&userspace_notification_inhibit))
 545                 return NOTIFY_DONE;
 546
 547         switch (event) {
 548         case PM_SUSPEND_PREPARE:
 549                 /*
 550                  * Queue an event to all "writer" users that we want
 551                  * to suspend and need their ack.
 552                  */
 553                 mutex_lock(&state_lock);
 554                 down_read(&user_list_lock);
 555
 556                 list_for_each_entry(as, &apm_user_list, list) {
 557                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
 558                             as->writer && as->suser) {
 559                                 as->suspend_state = SUSPEND_PENDING;
 560                                 atomic_inc(&suspend_acks_pending);
 561                                 queue_add_event(&as->queue, APM_USER_SUSPEND);
 562                         }
 563                 }
 564
 565                 up_read(&user_list_lock);
 566                 mutex_unlock(&state_lock);
 567                 wake_up_interruptible(&apm_waitqueue);
 568
 569                 /*
 570                  * Wait for the the suspend_acks_pending variable to drop to
 571                  * zero, meaning everybody acked the suspend event (or the
 572                  * process was killed.)
 573                  *
 574                  * If the app won't answer within a short while we assume it
 575                  * locked up and ignore it.
 576                  */
 577                 err = wait_event_interruptible_timeout(
 578                         apm_suspend_waitqueue,
 579                         atomic_read(&suspend_acks_pending) == 0,
 580                         5*HZ);
 581
 582                 /* timed out */
 583                 if (err == 0) {
 584                         /*
 585                          * Move anybody who timed out to "ack timeout" state.
 586                          *
 587                          * We could time out and the userspace does the ACK
 588                          * right after we time out but before we enter the
 589                          * locked section here, but that's fine.
 590                          */
 591                         mutex_lock(&state_lock);
 592                         down_read(&user_list_lock);
 593                         list_for_each_entry(as, &apm_user_list, list) {
 594                                 if (as->suspend_state == SUSPEND_PENDING ||
 595                                     as->suspend_state == SUSPEND_READ) {
 596                                         as->suspend_state = SUSPEND_ACKTO;
 597                                         atomic_dec(&suspend_acks_pending);
 598                                 }
 599                         }
 600                         up_read(&user_list_lock);
 601                         mutex_unlock(&state_lock);
 602                 }
 603
 604                 /* let suspend proceed */
 605                 if (err >= 0)
 606                         return NOTIFY_OK;
 607
 608                 /* interrupted by signal */
 609                 return NOTIFY_BAD;
 610
 611         case PM_POST_SUSPEND:
 612                 /*
 613                  * Anyone on the APM queues will think we're still suspended.
 614                  * Send a message so everyone knows we're now awake again.
 615                  */
 616                 queue_event(APM_NORMAL_RESUME);
 617
 618                 /*
 619                  * Finally, wake up anyone who is sleeping on the suspend.
 620                  */
 621                 mutex_lock(&state_lock);
 622                 down_read(&user_list_lock);
 623                 list_for_each_entry(as, &apm_user_list, list) {
 624                         if (as->suspend_state == SUSPEND_ACKED) {
 625                                 /*
 626                                  * TODO: maybe grab error code, needs core
 627                                  * changes to push the error to the notifier
 628                                  * chain (could use the second parameter if
 629                                  * implemented)
 630                                  */
 631                                 as->suspend_result = 0;
 632                                 as->suspend_state = SUSPEND_DONE;
 633                         }
 634                 }
 635                 up_read(&user_list_lock);
 636                 mutex_unlock(&state_lock);
 637
 638                 wake_up(&apm_suspend_waitqueue);
 639                 return NOTIFY_OK;
 640
 641         default:
 642                 return NOTIFY_DONE;
 643         }
 644 }
 645
 646 static struct notifier_block apm_notif_block = {
 647         .notifier_call = apm_suspend_notifier,
 648 };
 649
 650 static int __init apm_init(void)
 651 {
 652         int ret;
 653
 654         if (apm_disabled) {
 655                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 656                 return -ENODEV;
 657         }
 658
 659         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
 660         if (IS_ERR(kapmd_tsk)) {
 661                 ret = PTR_ERR(kapmd_tsk);
 662                 kapmd_tsk = NULL;
 663                 goto out;
 664         }
 665         wake_up_process(kapmd_tsk);
 666
 667 #ifdef CONFIG_PROC_FS
 668         proc_create("apm", 0, NULL, &apm_proc_fops);
 669 #endif
 670
 671         ret = misc_register(&apm_device);
 672         if (ret)
 673                 goto out_stop;
 674
 675         ret = register_pm_notifier(&apm_notif_block);
 676         if (ret)
 677                 goto out_unregister;
 678
 679         return 0;
 680
 681  out_unregister:
 682         misc_deregister(&apm_device);
 683  out_stop:
 684         remove_proc_entry("apm", NULL);
 685         kthread_stop(kapmd_tsk);
 686  out:
 687         return ret;
 688 }
 689
 690 static void __exit apm_exit(void)
 691 {
 692         unregister_pm_notifier(&apm_notif_block);
 693         misc_deregister(&apm_device);
 694         remove_proc_entry("apm", NULL);
 695
 696         kthread_stop(kapmd_tsk);
 697 }
 698
 699 module_init(apm_init);
 700 module_exit(apm_exit);
 701
 702 MODULE_AUTHOR("Stephen Rothwell");
 703 MODULE_DESCRIPTION("Advanced Power Management");
 704 MODULE_LICENSE("GPL");
 705
 706 #ifndef MODULE
 707 static int __init apm_setup(char *str)
 708 {
 709         while ((str != NULL) && (*str != '\0')) {
 710                 if (strncmp(str, "off", 3) == 0)
 711                         apm_disabled = 1;
 712                 if (strncmp(str, "on", 2) == 0)
 713                         apm_disabled = 0;
 714                 str = strchr(str, ',');
 715                 if (str != NULL)
 716                         str += strspn(str, ", \t");
 717         }
 718         return 1;
 719 }
 720
 721 __setup("apm=", apm_setup);
 722 #endif
 723
 724 /**
 725  * apm_queue_event - queue an APM event for kapmd
 726  * @event: APM event
 727  *
 728  * Queue an APM event for kapmd to process and ultimately take the
 729  * appropriate action.  Only a subset of events are handled:
 730  *   %APM_LOW_BATTERY
 731  *   %APM_POWER_STATUS_CHANGE
 732  *   %APM_USER_SUSPEND
 733  *   %APM_SYS_SUSPEND
 734  *   %APM_CRITICAL_SUSPEND
 735  */
 736 void apm_queue_event(apm_event_t event)
 737 {
 738         unsigned long flags;
 739
 740         spin_lock_irqsave(&kapmd_queue_lock, flags);
 741         queue_add_event(&kapmd_queue, event);
 742         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 743
 744         wake_up_interruptible(&kapmd_wait);
 745 }
 746 EXPORT_SYMBOL(apm_queue_event);