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 DEFINE_MUTEX(apm_mutex);
 130 static atomic_t suspend_acks_pending = ATOMIC_INIT(0);
 131 static atomic_t userspace_notification_inhibit = ATOMIC_INIT(0);
 132 static int apm_disabled;
 133 static struct task_struct *kapmd_tsk;
 134
 135 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
 136 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
 137
 138 /*
 139  * This is a list of everyone who has opened /dev/apm_bios
 140  */
 141 static DECLARE_RWSEM(user_list_lock);
 142 static LIST_HEAD(apm_user_list);
 143
 144 /*
 145  * kapmd info.  kapmd provides us a process context to handle
 146  * "APM" events within - specifically necessary if we're going
 147  * to be suspending the system.
 148  */
 149 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 150 static DEFINE_SPINLOCK(kapmd_queue_lock);
 151 static struct apm_queue kapmd_queue;
 152
 153 static DEFINE_MUTEX(state_lock);
 154
 155 static const char driver_version[] = "1.13";    /* no spaces */
 156
 157
 158
 159 /*
 160  * Compatibility cruft until the IPAQ people move over to the new
 161  * interface.
 162  */
 163 static void __apm_get_power_status(struct apm_power_info *info)
 164 {
 165 }
 166
 167 /*
 168  * This allows machines to provide their own "apm get power status" function.
 169  */
 170 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 171 EXPORT_SYMBOL(apm_get_power_status);
 172
 173
 174 /*
 175  * APM event queue management.
 176  */
 177 static inline int queue_empty(struct apm_queue *q)
 178 {
 179         return q->event_head == q->event_tail;
 180 }
 181
 182 static inline apm_event_t queue_get_event(struct apm_queue *q)
 183 {
 184         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 185         return q->events[q->event_tail];
 186 }
 187
 188 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 189 {
 190         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 191         if (q->event_head == q->event_tail) {
 192                 static int notified;
 193
 194                 if (notified++ == 0)
 195                     printk(KERN_ERR "apm: an event queue overflowed\n");
 196                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 197         }
 198         q->events[q->event_head] = event;
 199 }
 200
 201 static void queue_event(apm_event_t event)
 202 {
 203         struct apm_user *as;
 204
 205         down_read(&user_list_lock);
 206         list_for_each_entry(as, &apm_user_list, list) {
 207                 if (as->reader)
 208                         queue_add_event(&as->queue, event);
 209         }
 210         up_read(&user_list_lock);
 211         wake_up_interruptible(&apm_waitqueue);
 212 }
 213
 214 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 215 {
 216         struct apm_user *as = fp->private_data;
 217         apm_event_t event;
 218         int i = count, ret = 0;
 219
 220         if (count < sizeof(apm_event_t))
 221                 return -EINVAL;
 222
 223         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 224                 return -EAGAIN;
 225
 226         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 227
 228         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 229                 event = queue_get_event(&as->queue);
 230
 231                 ret = -EFAULT;
 232                 if (copy_to_user(buf, &event, sizeof(event)))
 233                         break;
 234
 235                 mutex_lock(&state_lock);
 236                 if (as->suspend_state == SUSPEND_PENDING &&
 237                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
 238                         as->suspend_state = SUSPEND_READ;
 239                 mutex_unlock(&state_lock);
 240
 241                 buf += sizeof(event);
 242                 i -= sizeof(event);
 243         }
 244
 245         if (i < count)
 246                 ret = count - i;
 247
 248         return ret;
 249 }
 250
 251 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 252 {
 253         struct apm_user *as = fp->private_data;
 254
 255         poll_wait(fp, &apm_waitqueue, wait);
 256         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 257 }
 258
 259 /*
 260  * apm_ioctl - handle APM ioctl
 261  *
 262  * APM_IOC_SUSPEND
 263  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 264  *     - initiate a suspend
 265  *     - acknowledge a suspend read from /dev/apm_bios.
 266  *   Only when everyone who has opened /dev/apm_bios with write permission
 267  *   has acknowledge does the actual suspend happen.
 268  */
 269 static long
 270 apm_ioctl(struct file *filp, u_int cmd, u_long arg)
 271 {
 272         struct apm_user *as = filp->private_data;
 273         int err = -EINVAL;
 274
 275         if (!as->suser || !as->writer)
 276                 return -EPERM;
 277
 278         mutex_lock(&apm_mutex);
 279         switch (cmd) {
 280         case APM_IOC_SUSPEND:
 281                 mutex_lock(&state_lock);
 282
 283                 as->suspend_result = -EINTR;
 284
 285                 switch (as->suspend_state) {
 286                 case SUSPEND_READ:
 287                         /*
 288                          * If we read a suspend command from /dev/apm_bios,
 289                          * then the corresponding APM_IOC_SUSPEND ioctl is
 290                          * interpreted as an acknowledge.
 291                          */
 292                         as->suspend_state = SUSPEND_ACKED;
 293                         atomic_dec(&suspend_acks_pending);
 294                         mutex_unlock(&state_lock);
 295
 296                         /*
 297                          * suspend_acks_pending changed, the notifier needs to
 298                          * be woken up for this
 299                          */
 300                         wake_up(&apm_suspend_waitqueue);
 301
 302                         /*
 303                          * Wait for the suspend/resume to complete.  If there
 304                          * are pending acknowledges, we wait here for them.
 305                          */
 306                         freezer_do_not_count();
 307
 308                         wait_event(apm_suspend_waitqueue,
 309                                    as->suspend_state == SUSPEND_DONE);
 310
 311                         /*
 312                          * Since we are waiting until the suspend is done, the
 313                          * try_to_freeze() in freezer_count() will not trigger
 314                          */
 315                         freezer_count();
 316                         break;
 317                 case SUSPEND_ACKTO:
 318                         as->suspend_result = -ETIMEDOUT;
 319                         mutex_unlock(&state_lock);
 320                         break;
 321                 default:
 322                         as->suspend_state = SUSPEND_WAIT;
 323                         mutex_unlock(&state_lock);
 324
 325                         /*
 326                          * Otherwise it is a request to suspend the system.
 327                          * Just invoke pm_suspend(), we'll handle it from
 328                          * there via the notifier.
 329                          */
 330                         as->suspend_result = pm_suspend(PM_SUSPEND_MEM);
 331                 }
 332
 333                 mutex_lock(&state_lock);
 334                 err = as->suspend_result;
 335                 as->suspend_state = SUSPEND_NONE;
 336                 mutex_unlock(&state_lock);
 337                 break;
 338         }
 339         mutex_unlock(&apm_mutex);
 340
 341         return err;
 342 }
 343
 344 static int apm_release(struct inode * inode, struct file * filp)
 345 {
 346         struct apm_user *as = filp->private_data;
 347
 348         filp->private_data = NULL;
 349
 350         down_write(&user_list_lock);
 351         list_del(&as->list);
 352         up_write(&user_list_lock);
 353
 354         /*
 355          * We are now unhooked from the chain.  As far as new
 356          * events are concerned, we no longer exist.
 357          */
 358         mutex_lock(&state_lock);
 359         if (as->suspend_state == SUSPEND_PENDING ||
 360             as->suspend_state == SUSPEND_READ)
 361                 atomic_dec(&suspend_acks_pending);
 362         mutex_unlock(&state_lock);
 363
 364         wake_up(&apm_suspend_waitqueue);
 365
 366         kfree(as);
 367         return 0;
 368 }
 369
 370 static int apm_open(struct inode * inode, struct file * filp)
 371 {
 372         struct apm_user *as;
 373
 374         mutex_lock(&apm_mutex);
 375         as = kzalloc(sizeof(*as), GFP_KERNEL);
 376         if (as) {
 377                 /*
 378                  * XXX - this is a tiny bit broken, when we consider BSD
 379                  * process accounting. If the device is opened by root, we
 380                  * instantly flag that we used superuser privs. Who knows,
 381                  * we might close the device immediately without doing a
 382                  * privileged operation -- cevans
 383                  */
 384                 as->suser = capable(CAP_SYS_ADMIN);
 385                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 386                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 387
 388                 down_write(&user_list_lock);
 389                 list_add(&as->list, &apm_user_list);
 390                 up_write(&user_list_lock);
 391
 392                 filp->private_data = as;
 393         }
 394         mutex_unlock(&apm_mutex);
 395
 396         return as ? 0 : -ENOMEM;
 397 }
 398
 399 static const struct file_operations apm_bios_fops = {
 400         .owner          = THIS_MODULE,
 401         .read           = apm_read,
 402         .poll           = apm_poll,
 403         .unlocked_ioctl = apm_ioctl,
 404         .open           = apm_open,
 405         .release        = apm_release,
 406         .llseek         = noop_llseek,
 407 };
 408
 409 static struct miscdevice apm_device = {
 410         .minor          = APM_MINOR_DEV,
 411         .name           = "apm_bios",
 412         .fops           = &apm_bios_fops
 413 };
 414
 415
 416 #ifdef CONFIG_PROC_FS
 417 /*
 418  * Arguments, with symbols from linux/apm_bios.h.
 419  *
 420  *   0) Linux driver version (this will change if format changes)
 421  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 422  *   2) APM flags from APM Installation Check (0x00):
 423  *      bit 0: APM_16_BIT_SUPPORT
 424  *      bit 1: APM_32_BIT_SUPPORT
 425  *      bit 2: APM_IDLE_SLOWS_CLOCK
 426  *      bit 3: APM_BIOS_DISABLED
 427  *      bit 4: APM_BIOS_DISENGAGED
 428  *   3) AC line status
 429  *      0x00: Off-line
 430  *      0x01: On-line
 431  *      0x02: On backup power (BIOS >= 1.1 only)
 432  *      0xff: Unknown
 433  *   4) Battery status
 434  *      0x00: High
 435  *      0x01: Low
 436  *      0x02: Critical
 437  *      0x03: Charging
 438  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 439  *      0xff: Unknown
 440  *   5) Battery flag
 441  *      bit 0: High
 442  *      bit 1: Low
 443  *      bit 2: Critical
 444  *      bit 3: Charging
 445  *      bit 7: No system battery
 446  *      0xff: Unknown
 447  *   6) Remaining battery life (percentage of charge):
 448  *      0-100: valid
 449  *      -1: Unknown
 450  *   7) Remaining battery life (time units):
 451  *      Number of remaining minutes or seconds
 452  *      -1: Unknown
 453  *   8) min = minutes; sec = seconds
 454  */
 455 static int proc_apm_show(struct seq_file *m, void *v)
 456 {
 457         struct apm_power_info info;
 458         char *units;
 459
 460         info.ac_line_status = 0xff;
 461         info.battery_status = 0xff;
 462         info.battery_flag   = 0xff;
 463         info.battery_life   = -1;
 464         info.time           = -1;
 465         info.units          = -1;
 466
 467         if (apm_get_power_status)
 468                 apm_get_power_status(&info);
 469
 470         switch (info.units) {
 471         default:        units = "?";    break;
 472         case 0:         units = "min";  break;
 473         case 1:         units = "sec";  break;
 474         }
 475
 476         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 477                      driver_version, APM_32_BIT_SUPPORT,
 478                      info.ac_line_status, info.battery_status,
 479                      info.battery_flag, info.battery_life,
 480                      info.time, units);
 481
 482         return 0;
 483 }
 484
 485 static int proc_apm_open(struct inode *inode, struct file *file)
 486 {
 487         return single_open(file, proc_apm_show, NULL);
 488 }
 489
 490 static const struct file_operations apm_proc_fops = {
 491         .owner          = THIS_MODULE,
 492         .open           = proc_apm_open,
 493         .read           = seq_read,
 494         .llseek         = seq_lseek,
 495         .release        = single_release,
 496 };
 497 #endif
 498
 499 static int kapmd(void *arg)
 500 {
 501         do {
 502                 apm_event_t event;
 503
 504                 wait_event_interruptible(kapmd_wait,
 505                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
 506
 507                 if (kthread_should_stop())
 508                         break;
 509
 510                 spin_lock_irq(&kapmd_queue_lock);
 511                 event = 0;
 512                 if (!queue_empty(&kapmd_queue))
 513                         event = queue_get_event(&kapmd_queue);
 514                 spin_unlock_irq(&kapmd_queue_lock);
 515
 516                 switch (event) {
 517                 case 0:
 518                         break;
 519
 520                 case APM_LOW_BATTERY:
 521                 case APM_POWER_STATUS_CHANGE:
 522                         queue_event(event);
 523                         break;
 524
 525                 case APM_USER_SUSPEND:
 526                 case APM_SYS_SUSPEND:
 527                         pm_suspend(PM_SUSPEND_MEM);
 528                         break;
 529
 530                 case APM_CRITICAL_SUSPEND:
 531                         atomic_inc(&userspace_notification_inhibit);
 532                         pm_suspend(PM_SUSPEND_MEM);
 533                         atomic_dec(&userspace_notification_inhibit);
 534                         break;
 535                 }
 536         } while (1);
 537
 538         return 0;
 539 }
 540
 541 static int apm_suspend_notifier(struct notifier_block *nb,
 542                                 unsigned long event,
 543                                 void *dummy)
 544 {
 545         struct apm_user *as;
 546         int err;
 547
 548         /* short-cut emergency suspends */
 549         if (atomic_read(&userspace_notification_inhibit))
 550                 return NOTIFY_DONE;
 551
 552         switch (event) {
 553         case PM_SUSPEND_PREPARE:
 554                 /*
 555                  * Queue an event to all "writer" users that we want
 556                  * to suspend and need their ack.
 557                  */
 558                 mutex_lock(&state_lock);
 559                 down_read(&user_list_lock);
 560
 561                 list_for_each_entry(as, &apm_user_list, list) {
 562                         if (as->suspend_state != SUSPEND_WAIT && as->reader &&
 563                             as->writer && as->suser) {
 564                                 as->suspend_state = SUSPEND_PENDING;
 565                                 atomic_inc(&suspend_acks_pending);
 566                                 queue_add_event(&as->queue, APM_USER_SUSPEND);
 567                         }
 568                 }
 569
 570                 up_read(&user_list_lock);
 571                 mutex_unlock(&state_lock);
 572                 wake_up_interruptible(&apm_waitqueue);
 573
 574                 /*
 575                  * Wait for the the suspend_acks_pending variable to drop to
 576                  * zero, meaning everybody acked the suspend event (or the
 577                  * process was killed.)
 578                  *
 579                  * If the app won't answer within a short while we assume it
 580                  * locked up and ignore it.
 581                  */
 582                 err = wait_event_interruptible_timeout(
 583                         apm_suspend_waitqueue,
 584                         atomic_read(&suspend_acks_pending) == 0,
 585                         5*HZ);
 586
 587                 /* timed out */
 588                 if (err == 0) {
 589                         /*
 590                          * Move anybody who timed out to "ack timeout" state.
 591                          *
 592                          * We could time out and the userspace does the ACK
 593                          * right after we time out but before we enter the
 594                          * locked section here, but that's fine.
 595                          */
 596                         mutex_lock(&state_lock);
 597                         down_read(&user_list_lock);
 598                         list_for_each_entry(as, &apm_user_list, list) {
 599                                 if (as->suspend_state == SUSPEND_PENDING ||
 600                                     as->suspend_state == SUSPEND_READ) {
 601                                         as->suspend_state = SUSPEND_ACKTO;
 602                                         atomic_dec(&suspend_acks_pending);
 603                                 }
 604                         }
 605                         up_read(&user_list_lock);
 606                         mutex_unlock(&state_lock);
 607                 }
 608
 609                 /* let suspend proceed */
 610                 if (err >= 0)
 611                         return NOTIFY_OK;
 612
 613                 /* interrupted by signal */
 614                 return NOTIFY_BAD;
 615
 616         case PM_POST_SUSPEND:
 617                 /*
 618                  * Anyone on the APM queues will think we're still suspended.
 619                  * Send a message so everyone knows we're now awake again.
 620                  */
 621                 queue_event(APM_NORMAL_RESUME);
 622
 623                 /*
 624                  * Finally, wake up anyone who is sleeping on the suspend.
 625                  */
 626                 mutex_lock(&state_lock);
 627                 down_read(&user_list_lock);
 628                 list_for_each_entry(as, &apm_user_list, list) {
 629                         if (as->suspend_state == SUSPEND_ACKED) {
 630                                 /*
 631                                  * TODO: maybe grab error code, needs core
 632                                  * changes to push the error to the notifier
 633                                  * chain (could use the second parameter if
 634                                  * implemented)
 635                                  */
 636                                 as->suspend_result = 0;
 637                                 as->suspend_state = SUSPEND_DONE;
 638                         }
 639                 }
 640                 up_read(&user_list_lock);
 641                 mutex_unlock(&state_lock);
 642
 643                 wake_up(&apm_suspend_waitqueue);
 644                 return NOTIFY_OK;
 645
 646         default:
 647                 return NOTIFY_DONE;
 648         }
 649 }
 650
 651 static struct notifier_block apm_notif_block = {
 652         .notifier_call = apm_suspend_notifier,
 653 };
 654
 655 static int __init apm_init(void)
 656 {
 657         int ret;
 658
 659         if (apm_disabled) {
 660                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 661                 return -ENODEV;
 662         }
 663
 664         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
 665         if (IS_ERR(kapmd_tsk)) {
 666                 ret = PTR_ERR(kapmd_tsk);
 667                 kapmd_tsk = NULL;
 668                 goto out;
 669         }
 670         wake_up_process(kapmd_tsk);
 671
 672 #ifdef CONFIG_PROC_FS
 673         proc_create("apm", 0, NULL, &apm_proc_fops);
 674 #endif
 675
 676         ret = misc_register(&apm_device);
 677         if (ret)
 678                 goto out_stop;
 679
 680         ret = register_pm_notifier(&apm_notif_block);
 681         if (ret)
 682                 goto out_unregister;
 683
 684         return 0;
 685
 686  out_unregister:
 687         misc_deregister(&apm_device);
 688  out_stop:
 689         remove_proc_entry("apm", NULL);
 690         kthread_stop(kapmd_tsk);
 691  out:
 692         return ret;
 693 }
 694
 695 static void __exit apm_exit(void)
 696 {
 697         unregister_pm_notifier(&apm_notif_block);
 698         misc_deregister(&apm_device);
 699         remove_proc_entry("apm", NULL);
 700
 701         kthread_stop(kapmd_tsk);
 702 }
 703
 704 module_init(apm_init);
 705 module_exit(apm_exit);
 706
 707 MODULE_AUTHOR("Stephen Rothwell");
 708 MODULE_DESCRIPTION("Advanced Power Management");
 709 MODULE_LICENSE("GPL");
 710
 711 #ifndef MODULE
 712 static int __init apm_setup(char *str)
 713 {
 714         while ((str != NULL) && (*str != '\0')) {
 715                 if (strncmp(str, "off", 3) == 0)
 716                         apm_disabled = 1;
 717                 if (strncmp(str, "on", 2) == 0)
 718                         apm_disabled = 0;
 719                 str = strchr(str, ',');
 720                 if (str != NULL)
 721                         str += strspn(str, ", \t");
 722         }
 723         return 1;
 724 }
 725
 726 __setup("apm=", apm_setup);
 727 #endif
 728
 729 /**
 730  * apm_queue_event - queue an APM event for kapmd
 731  * @event: APM event
 732  *
 733  * Queue an APM event for kapmd to process and ultimately take the
 734  * appropriate action.  Only a subset of events are handled:
 735  *   %APM_LOW_BATTERY
 736  *   %APM_POWER_STATUS_CHANGE
 737  *   %APM_USER_SUSPEND
 738  *   %APM_SYS_SUSPEND
 739  *   %APM_CRITICAL_SUSPEND
 740  */
 741 void apm_queue_event(apm_event_t event)
 742 {
 743         unsigned long flags;
 744
 745         spin_lock_irqsave(&kapmd_queue_lock, flags);
 746         queue_add_event(&kapmd_queue, event);
 747         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 748
 749         wake_up_interruptible(&kapmd_wait);
 750 }
 751 EXPORT_SYMBOL(apm_queue_event);