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