drivers/char/apm-emulation.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * bios-less APM driver for ARM Linux
   4  *  Jamey Hicks <jamey@crl.dec.com>
   5  *  adapted from the APM BIOS driver for Linux by Stephen Rothwell (sfr@linuxcare.com)
   6  *
   7  * APM 1.2 Reference:
   8  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
   9  *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
  10  *
  11  * This document is available from Microsoft at:
  12  *    http://www.microsoft.com/whdc/archive/amp_12.mspx
  13  */
  14 #include <linux/module.h>
  15 #include <linux/poll.h>
  16 #include <linux/slab.h>
  17 #include <linux/mutex.h>
  18 #include <linux/proc_fs.h>
  19 #include <linux/seq_file.h>
  20 #include <linux/miscdevice.h>
  21 #include <linux/apm_bios.h>
  22 #include <linux/capability.h>
  23 #include <linux/sched.h>
  24 #include <linux/suspend.h>
  25 #include <linux/apm-emulation.h>
  26 #include <linux/freezer.h>
  27 #include <linux/device.h>
  28 #include <linux/kernel.h>
  29 #include <linux/list.h>
  30 #include <linux/init.h>
  31 #include <linux/completion.h>
  32 #include <linux/kthread.h>
  33 #include <linux/delay.h>
  34
  35 /*
  36  * One option can be changed at boot time as follows:
  37  *      apm=on/off                      enable/disable APM
  38  */
  39
  40 /*
  41  * Maximum number of events stored
  42  */
  43 #define APM_MAX_EVENTS          16
  44
  45 struct apm_queue {
  46         unsigned int            event_head;
  47         unsigned int            event_tail;
  48         apm_event_t             events[APM_MAX_EVENTS];
  49 };
  50
  51 /*
  52  * thread states (for threads using a writable /dev/apm_bios fd):
  53  *
  54  * SUSPEND_NONE:        nothing happening
  55  * SUSPEND_PENDING:     suspend event queued for thread and pending to be read
  56  * SUSPEND_READ:        suspend event read, pending acknowledgement
  57  * SUSPEND_ACKED:       acknowledgement received from thread (via ioctl),
  58  *                      waiting for resume
  59  * SUSPEND_ACKTO:       acknowledgement timeout
  60  * SUSPEND_DONE:        thread had acked suspend and is now notified of
  61  *                      resume
  62  *
  63  * SUSPEND_WAIT:        this thread invoked suspend and is waiting for resume
  64  *
  65  * A thread migrates in one of three paths:
  66  *      NONE -1-> PENDING -2-> READ -3-> ACKED -4-> DONE -5-> NONE
  67  *                                  -6-> ACKTO -7-> NONE
  68  *      NONE -8-> WAIT -9-> NONE
  69  *
  70  * While in PENDING or READ, the thread is accounted for in the
  71  * suspend_acks_pending counter.
  72  *
  73  * The transitions are invoked as follows:
  74  *      1: suspend event is signalled from the core PM code
  75  *      2: the suspend event is read from the fd by the userspace thread
  76  *      3: userspace thread issues the APM_IOC_SUSPEND ioctl (as ack)
  77  *      4: core PM code signals that we have resumed
  78  *      5: APM_IOC_SUSPEND ioctl returns
  79  *
  80  *      6: the notifier invoked from the core PM code timed out waiting
  81  *         for all relevant threds to enter ACKED state and puts those
  82  *         that haven't into ACKTO
  83  *      7: those threads issue APM_IOC_SUSPEND ioctl too late,
  84  *         get an error
  85  *
  86  *      8: userspace thread issues the APM_IOC_SUSPEND ioctl (to suspend),
  87  *         ioctl code invokes pm_suspend()
  88  *      9: pm_suspend() returns indicating resume
  89  */
  90 enum apm_suspend_state {
  91         SUSPEND_NONE,
  92         SUSPEND_PENDING,
  93         SUSPEND_READ,
  94         SUSPEND_ACKED,
  95         SUSPEND_ACKTO,
  96         SUSPEND_WAIT,
  97         SUSPEND_DONE,
  98 };
  99
 100 /*
 101  * The per-file APM data
 102  */
 103 struct apm_user {
 104         struct list_head        list;
 105
 106         unsigned int            suser: 1;
 107         unsigned int            writer: 1;
 108         unsigned int            reader: 1;
 109
 110         int                     suspend_result;
 111         enum apm_suspend_state  suspend_state;
 112
 113         struct apm_queue        queue;
 114 };
 115
 116 /*
 117  * Local variables
 118  */
 119 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
 120 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
 121 static int apm_disabled;
 122 static struct task_struct *kapmd_tsk;
 123
 124 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
 125 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
 126
 127 /*
 128  * This is a list of everyone who has opened /dev/apm_bios
 129  */
 130 static DECLARE_RWSEM(user_list_lock);
 131 static LIST_HEAD(apm_user_list);
 132
 133 /*
 134  * kapmd info.  kapmd provides us a process context to handle
 135  * "APM" events within - specifically necessary if we're going
 136  * to be suspending the system.
 137  */
 138 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 139 static DEFINE_SPINLOCK(kapmd_queue_lock);
 140 static struct apm_queue kapmd_queue;
 141
 142 static DEFINE_MUTEX(state_lock);
 143
 144 static const char driver_version[] = "1.13";    /* no spaces */
 145
 146
 147
 148 /*
 149  * Compatibility cruft until the IPAQ people move over to the new
 150  * interface.
 151  */
 152 static void __apm_get_power_status(struct apm_power_info *info)
 153 {
 154 }
 155
 156 /*
 157  * This allows machines to provide their own "apm get power status" function.
 158  */
 159 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 160 EXPORT_SYMBOL(apm_get_power_status);
 161
 162
 163 /*
 164  * APM event queue management.
 165  */
 166 static inline int queue_empty(struct apm_queue *q)
 167 {
 168         return q->event_head == q->event_tail;
 169 }
 170
 171 static inline apm_event_t queue_get_event(struct apm_queue *q)
 172 {
 173         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 174         return q->events[q->event_tail];
 175 }
 176
 177 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 178 {
 179         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 180         if (q->event_head == q->event_tail) {
 181                 static int notified;
 182
 183                 if (notified++ == 0)
 184                     printk(KERN_ERR "apm: an event queue overflowed\n");
 185                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 186         }
 187         q->events[q->event_head] = event;
 188 }
 189
 190 static void queue_event(apm_event_t event)
 191 {
 192         struct apm_user *as;
 193
 194         down_read(&user_list_lock);
 195         list_for_each_entry(as, &apm_user_list, list) {
 196                 if (as->reader)
 197                         queue_add_event(&as->queue, event);
 198         }
 199         up_read(&user_list_lock);
 200         wake_up_interruptible(&apm_waitqueue);
 201 }
 202
 203 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 204 {
 205         struct apm_user *as = fp->private_data;
 206         apm_event_t event;
 207         int i = count, ret = 0;
 208
 209         if (count < sizeof(apm_event_t))
 210                 return -EINVAL;
 211
 212         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 213                 return -EAGAIN;
 214
 215         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 216
 217         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 218                 event = queue_get_event(&as->queue);
 219
 220                 ret = -EFAULT;
 221                 if (copy_to_user(buf, &event, sizeof(event)))
 222                         break;
 223
 224                 mutex_lock(&state_lock);
 225                 if (as->suspend_state == SUSPEND_PENDING &&
 226                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
 227                         as->suspend_state = SUSPEND_READ;
 228                 mutex_unlock(&state_lock);
 229
 230                 buf += sizeof(event);
 231                 i -= sizeof(event);
 232         }
 233
 234         if (i < count)
 235                 ret = count - i;
 236
 237         return ret;
 238 }
 239
 240 static __poll_t apm_poll(struct file *fp, poll_table * wait)
 241 {
 242         struct apm_user *as = fp->private_data;
 243
 244         poll_wait(fp, &apm_waitqueue, wait);
 245         return queue_empty(&as->queue) ? 0 : EPOLLIN | EPOLLRDNORM;
 246 }
 247
 248 /*
 249  * apm_ioctl - handle APM ioctl
 250  *
 251  * APM_IOC_SUSPEND
 252  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 253  *     - initiate a suspend
 254  *     - acknowledge a suspend read from /dev/apm_bios.
 255  *   Only when everyone who has opened /dev/apm_bios with write permission
 256  *   has acknowledge does the actual suspend happen.
 257  */
 258 static long
 259 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
 260 {
 261         struct apm_user *as = filp->private_data;
 262         int err = -EINVAL;
 263
 264         if (!as->suser || !as->writer)
 265                 return -EPERM;
 266
 267         switch (cmd) {
 268         case APM_IOC_SUSPEND:
 269                 mutex_lock(&state_lock);
 270
 271                 as->suspend_result = -EINTR;
 272
 273                 switch (as->suspend_state) {
 274                 case SUSPEND_READ:
 275                         /*
 276                          * If we read a suspend command from /dev/apm_bios,
 277                          * then the corresponding APM_IOC_SUSPEND ioctl is
 278                          * interpreted as an acknowledge.
 279                          */
 280                         as->suspend_state = SUSPEND_ACKED;
 281                         atomic_dec(&suspend_acks_pending);
 282                         mutex_unlock(&state_lock);
 283
 284                         /*
 285                          * suspend_acks_pending changed, the notifier needs to
 286                          * be woken up for this
 287                          */
 288                         wake_up(&apm_suspend_waitqueue);
 289
 290                         /*
 291                          * Wait for the suspend/resume to complete.  If there
 292                          * are pending acknowledges, we wait here for them.
 293                          * wait_event_freezable() is interruptible and pending
 294                          * signal can cause busy looping.  We aren't doing
 295                          * anything critical, chill a bit on each iteration.
 296                          */
 297                         while (wait_event_freezable(apm_suspend_waitqueue,
 298                                         as->suspend_state != SUSPEND_ACKED))
 299                                 msleep(10);
 300                         break;
 301                 case SUSPEND_ACKTO:
 302                         as->suspend_result = -ETIMEDOUT;
 303                         mutex_unlock(&state_lock);
 304                         break;
 305                 default:
 306                         as->suspend_state = SUSPEND_WAIT;
 307                         mutex_unlock(&state_lock);
 308
 309                         /*
 310                          * Otherwise it is a request to suspend the system.
 311                          * Just invoke pm_suspend(), we'll handle it from
 312                          * there via the notifier.
 313                          */
 314                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
 315                 }
 316
 317                 mutex_lock(&state_lock);
 318                 err = as->suspend_result;
 319                 as->suspend_state = SUSPEND_NONE;
 320                 mutex_unlock(&state_lock);
 321                 break;
 322         }
 323
 324         return err;
 325 }
 326
 327 static int apm_release(struct inode * inode, struct file * filp)
 328 {
 329         struct apm_user *as = filp->private_data;
 330
 331         filp->private_data = NULL;
 332
 333         down_write(&user_list_lock);
 334         list_del(&as->list);
 335         up_write(&user_list_lock);
 336
 337         /*
 338          * We are now unhooked from the chain.  As far as new
 339          * events are concerned, we no longer exist.
 340          */
 341         mutex_lock(&state_lock);
 342         if (as->suspend_state == SUSPEND_PENDING ||
 343             as->suspend_state == SUSPEND_READ)
 344                 atomic_dec(&suspend_acks_pending);
 345         mutex_unlock(&state_lock);
 346
 347         wake_up(&apm_suspend_waitqueue);
 348
 349         kfree(as);
 350         return 0;
 351 }
 352
 353 static int apm_open(struct inode * inode, struct file * filp)
 354 {
 355         struct apm_user *as;
 356
 357         as = kzalloc(sizeof(*as), GFP_KERNEL);
 358         if (as) {
 359                 /*
 360                  * XXX - this is a tiny bit broken, when we consider BSD
 361                  * process accounting. If the device is opened by root, we
 362                  * instantly flag that we used superuser privs. Who knows,
 363                  * we might close the device immediately without doing a
 364                  * privileged operation -- cevans
 365                  */
 366                 as->suser = capable(CAP_SYS_ADMIN);
 367                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 368                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 369
 370                 down_write(&user_list_lock);
 371                 list_add(&as->list, &apm_user_list);
 372                 up_write(&user_list_lock);
 373
 374                 filp->private_data = as;
 375         }
 376
 377         return as ? 0 : -ENOMEM;
 378 }
 379
 380 static const struct file_operations apm_bios_fops = {
 381         .owner          = THIS_MODULE,
 382         .read           = apm_read,
 383         .poll           = apm_poll,
 384         .unlocked_ioctl = apm_ioctl,
 385         .open           = apm_open,
 386         .release        = apm_release,
 387         .llseek         = noop_llseek,
 388 };
 389
 390 static struct miscdevice apm_device = {
 391         .minor          = APM_MINOR_DEV,
 392         .name           = "apm_bios",
 393         .fops           = &apm_bios_fops
 394 };
 395
 396
 397 #ifdef CONFIG_PROC_FS
 398 /*
 399  * Arguments, with symbols from linux/apm_bios.h.
 400  *
 401  *   0) Linux driver version (this will change if format changes)
 402  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 403  *   2) APM flags from APM Installation Check (0x00):
 404  *      bit 0: APM_16_BIT_SUPPORT
 405  *      bit 1: APM_32_BIT_SUPPORT
 406  *      bit 2: APM_IDLE_SLOWS_CLOCK
 407  *      bit 3: APM_BIOS_DISABLED
 408  *      bit 4: APM_BIOS_DISENGAGED
 409  *   3) AC line status
 410  *      0x00: Off-line
 411  *      0x01: On-line
 412  *      0x02: On backup power (BIOS >= 1.1 only)
 413  *      0xff: Unknown
 414  *   4) Battery status
 415  *      0x00: High
 416  *      0x01: Low
 417  *      0x02: Critical
 418  *      0x03: Charging
 419  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 420  *      0xff: Unknown
 421  *   5) Battery flag
 422  *      bit 0: High
 423  *      bit 1: Low
 424  *      bit 2: Critical
 425  *      bit 3: Charging
 426  *      bit 7: No system battery
 427  *      0xff: Unknown
 428  *   6) Remaining battery life (percentage of charge):
 429  *      0-100: valid
 430  *      -1: Unknown
 431  *   7) Remaining battery life (time units):
 432  *      Number of remaining minutes or seconds
 433  *      -1: Unknown
 434  *   8) min = minutes; sec = seconds
 435  */
 436 static int proc_apm_show(struct seq_file *m, void *v)
 437 {
 438         struct apm_power_info info;
 439         char *units;
 440
 441         info.ac_line_status = 0xff;
 442         info.battery_status = 0xff;
 443         info.battery_flag   = 0xff;
 444         info.battery_life   = -1;
 445         info.time           = -1;
 446         info.units          = -1;
 447
 448         if (apm_get_power_status)
 449                 apm_get_power_status(&info);
 450
 451         switch (info.units) {
 452         default:        units = "?";    break;
 453         case 0:         units = "min";  break;
 454         case 1:         units = "sec";  break;
 455         }
 456
 457         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 458                      driver_version, APM_32_BIT_SUPPORT,
 459                      info.ac_line_status, info.battery_status,
 460                      info.battery_flag, info.battery_life,
 461                      info.time, units);
 462
 463         return 0;
 464 }
 465 #endif
 466
 467 static int kapmd(void *arg)
 468 {
 469         do {
 470                 apm_event_t event;
 471
 472                 wait_event_interruptible(kapmd_wait,
 473                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
 474
 475                 if (kthread_should_stop())
 476                         break;
 477
 478                 spin_lock_irq(&kapmd_queue_lock);
 479                 event = 0;
 480                 if (!queue_empty(&kapmd_queue))
 481                         event = queue_get_event(&kapmd_queue);
 482                 spin_unlock_irq(&kapmd_queue_lock);
 483
 484                 switch (event) {
 485                 case 0:
 486                         break;
 487
 488                 case APM_LOW_BATTERY:
 489                 case APM_POWER_STATUS_CHANGE:
 490                         queue_event(event);
 491                         break;
 492
 493                 case APM_USER_SUSPEND:
 494                 case APM_SYS_SUSPEND:
 495                         pm_suspend(PM_SUSPEND_MEM);
 496                         break;
 497
 498                 case APM_CRITICAL_SUSPEND:
 499                         atomic_inc(&userspace_notification_inhibit);
 500                         pm_suspend(PM_SUSPEND_MEM);
 501                         atomic_dec(&userspace_notification_inhibit);
 502                         break;
 503                 }
 504         } while (1);
 505
 506         return 0;
 507 }
 508
 509 static int apm_suspend_notifier(struct notifier_block *nb,
 510                                 unsigned long event,
 511                                 void *dummy)
 512 {
 513         struct apm_user *as;
 514         int err;
 515         unsigned long apm_event;
 516
 517         /* short-cut emergency suspends */
 518         if (atomic_read(&userspace_notification_inhibit))
 519                 return NOTIFY_DONE;
 520
 521         switch (event) {
 522         case PM_SUSPEND_PREPARE:
 523         case PM_HIBERNATION_PREPARE:
 524                 apm_event = (event == PM_SUSPEND_PREPARE) ?
 525                         APM_USER_SUSPEND : APM_USER_HIBERNATION;
 526                 /*
 527                  * Queue an event to all "writer" users that we want
 528                  * to suspend and need their ack.
 529                  */
 530                 mutex_lock(&state_lock);
 531                 down_read(&user_list_lock);
 532
 533                 list_for_each_entry(as, &apm_user_list, list) {
 534                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
 535                             as->writer && as->suser) {
 536                                 as->suspend_state = SUSPEND_PENDING;
 537                                 atomic_inc(&suspend_acks_pending);
 538                                 queue_add_event(&as->queue, apm_event);
 539                         }
 540                 }
 541
 542                 up_read(&user_list_lock);
 543                 mutex_unlock(&state_lock);
 544                 wake_up_interruptible(&apm_waitqueue);
 545
 546                 /*
 547                  * Wait for the the suspend_acks_pending variable to drop to
 548                  * zero, meaning everybody acked the suspend event (or the
 549                  * process was killed.)
 550                  *
 551                  * If the app won't answer within a short while we assume it
 552                  * locked up and ignore it.
 553                  */
 554                 err = wait_event_interruptible_timeout(
 555                         apm_suspend_waitqueue,
 556                         atomic_read(&suspend_acks_pending) == 0,
 557                         5*HZ);
 558
 559                 /* timed out */
 560                 if (err == 0) {
 561                         /*
 562                          * Move anybody who timed out to "ack timeout" state.
 563                          *
 564                          * We could time out and the userspace does the ACK
 565                          * right after we time out but before we enter the
 566                          * locked section here, but that's fine.
 567                          */
 568                         mutex_lock(&state_lock);
 569                         down_read(&user_list_lock);
 570                         list_for_each_entry(as, &apm_user_list, list) {
 571                                 if (as->suspend_state == SUSPEND_PENDING ||
 572                                     as->suspend_state == SUSPEND_READ) {
 573                                         as->suspend_state = SUSPEND_ACKTO;
 574                                         atomic_dec(&suspend_acks_pending);
 575                                 }
 576                         }
 577                         up_read(&user_list_lock);
 578                         mutex_unlock(&state_lock);
 579                 }
 580
 581                 /* let suspend proceed */
 582                 if (err >= 0)
 583                         return NOTIFY_OK;
 584
 585                 /* interrupted by signal */
 586                 return notifier_from_errno(err);
 587
 588         case PM_POST_SUSPEND:
 589         case PM_POST_HIBERNATION:
 590                 apm_event = (event == PM_POST_SUSPEND) ?
 591                         APM_NORMAL_RESUME : APM_HIBERNATION_RESUME;
 592                 /*
 593                  * Anyone on the APM queues will think we're still suspended.
 594                  * Send a message so everyone knows we're now awake again.
 595                  */
 596                 queue_event(apm_event);
 597
 598                 /*
 599                  * Finally, wake up anyone who is sleeping on the suspend.
 600                  */
 601                 mutex_lock(&state_lock);
 602                 down_read(&user_list_lock);
 603                 list_for_each_entry(as, &apm_user_list, list) {
 604                         if (as->suspend_state == SUSPEND_ACKED) {
 605                                 /*
 606                                  * TODO: maybe grab error code, needs core
 607                                  * changes to push the error to the notifier
 608                                  * chain (could use the second parameter if
 609                                  * implemented)
 610                                  */
 611                                 as->suspend_result = 0;
 612                                 as->suspend_state = SUSPEND_DONE;
 613                         }
 614                 }
 615                 up_read(&user_list_lock);
 616                 mutex_unlock(&state_lock);
 617
 618                 wake_up(&apm_suspend_waitqueue);
 619                 return NOTIFY_OK;
 620
 621         default:
 622                 return NOTIFY_DONE;
 623         }
 624 }
 625
 626 static struct notifier_block apm_notif_block = {
 627         .notifier_call = apm_suspend_notifier,
 628 };
 629
 630 static int __init apm_init(void)
 631 {
 632         int ret;
 633
 634         if (apm_disabled) {
 635                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 636                 return -ENODEV;
 637         }
 638
 639         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
 640         if (IS_ERR(kapmd_tsk)) {
 641                 ret = PTR_ERR(kapmd_tsk);
 642                 kapmd_tsk = NULL;
 643                 goto out;
 644         }
 645         wake_up_process(kapmd_tsk);
 646
 647 #ifdef CONFIG_PROC_FS
 648         proc_create_single("apm", 0, NULL, proc_apm_show);
 649 #endif
 650
 651         ret = misc_register(&apm_device);
 652         if (ret)
 653                 goto out_stop;
 654
 655         ret = register_pm_notifier(&apm_notif_block);
 656         if (ret)
 657                 goto out_unregister;
 658
 659         return 0;
 660
 661  out_unregister:
 662         misc_deregister(&apm_device);
 663  out_stop:
 664         remove_proc_entry("apm", NULL);
 665         kthread_stop(kapmd_tsk);
 666  out:
 667         return ret;
 668 }
 669
 670 static void __exit apm_exit(void)
 671 {
 672         unregister_pm_notifier(&apm_notif_block);
 673         misc_deregister(&apm_device);
 674         remove_proc_entry("apm", NULL);
 675
 676         kthread_stop(kapmd_tsk);
 677 }
 678
 679 module_init(apm_init);
 680 module_exit(apm_exit);
 681
 682 MODULE_AUTHOR("Stephen Rothwell");
 683 MODULE_DESCRIPTION("Advanced Power Management");
 684 MODULE_LICENSE("GPL");
 685
 686 #ifndef MODULE
 687 static int __init apm_setup(char *str)
 688 {
 689         while ((str != NULL) && (*str != '\0')) {
 690                 if (strncmp(str, "off", 3) == 0)
 691                         apm_disabled = 1;
 692                 if (strncmp(str, "on", 2) == 0)
 693                         apm_disabled = 0;
 694                 str = strchr(str, ',');
 695                 if (str != NULL)
 696                         str += strspn(str, ", \t");
 697         }
 698         return 1;
 699 }
 700
 701 __setup("apm=", apm_setup);
 702 #endif
 703
 704 /**
 705  * apm_queue_event - queue an APM event for kapmd
 706  * @event: APM event
 707  *
 708  * Queue an APM event for kapmd to process and ultimately take the
 709  * appropriate action.  Only a subset of events are handled:
 710  *   %APM_LOW_BATTERY
 711  *   %APM_POWER_STATUS_CHANGE
 712  *   %APM_USER_SUSPEND
 713  *   %APM_SYS_SUSPEND
 714  *   %APM_CRITICAL_SUSPEND
 715  */
 716 void apm_queue_event(apm_event_t event)
 717 {
 718         unsigned long flags;
 719
 720         spin_lock_irqsave(&kapmd_queue_lock, flags);
 721         queue_add_event(&kapmd_queue, event);
 722         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 723
 724         wake_up_interruptible(&kapmd_wait);
 725 }
 726 EXPORT_SYMBOL(apm_queue_event);