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