git.oblomov.eu Git - linux-2.6/blob - 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/hwdev/busbios/amp_12.htm]
  12  */
  13 #include <linux/module.h>
  14 #include <linux/poll.h>
  15 #include <linux/slab.h>
  16 #include <linux/proc_fs.h>
  17 #include <linux/seq_file.h>
  18 #include <linux/miscdevice.h>
  19 #include <linux/apm_bios.h>
  20 #include <linux/capability.h>
  21 #include <linux/sched.h>
  22 #include <linux/suspend.h>
  23 #include <linux/apm-emulation.h>
  24 #include <linux/freezer.h>
  25 #include <linux/device.h>
  26 #include <linux/kernel.h>
  27 #include <linux/list.h>
  28 #include <linux/init.h>
  29 #include <linux/completion.h>
  30 #include <linux/kthread.h>
  31 #include <linux/delay.h>
  32
  33 #include <asm/system.h>
  34
  35 /*
  36  * The apm_bios device is one of the misc char devices.
  37  * This is its minor number.
  38  */
  39 #define APM_MINOR_DEV   134
  40
  41 /*
  42  * See Documentation/Config.help for the configuration options.
  43  *
  44  * Various options can be changed at boot time as follows:
  45  * (We allow underscores for compatibility with the modules code)
  46  *      apm=on/off                      enable/disable APM
  47  */
  48
  49 /*
  50  * Maximum number of events stored
  51  */
  52 #define APM_MAX_EVENTS          16
  53
  54 struct apm_queue {
  55         unsigned int            event_head;
  56         unsigned int            event_tail;
  57         apm_event_t             events[APM_MAX_EVENTS];
  58 };
  59
  60 /*
  61  * The per-file APM data
  62  */
  63 struct apm_user {
  64         struct list_head        list;
  65
  66         unsigned int            suser: 1;
  67         unsigned int            writer: 1;
  68         unsigned int            reader: 1;
  69
  70         int                     suspend_result;
  71         unsigned int            suspend_state;
  72 #define SUSPEND_NONE    0               /* no suspend pending */
  73 #define SUSPEND_PENDING 1               /* suspend pending read */
  74 #define SUSPEND_READ    2               /* suspend read, pending ack */
  75 #define SUSPEND_ACKED   3               /* suspend acked */
  76 #define SUSPEND_WAIT    4               /* waiting for suspend */
  77 #define SUSPEND_DONE    5               /* suspend completed */
  78
  79         struct apm_queue        queue;
  80 };
  81
  82 /*
  83  * Local variables
  84  */
  85 static int suspends_pending;
  86 static int apm_disabled;
  87 static struct task_struct *kapmd_tsk;
  88
  89 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
  90 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
  91
  92 /*
  93  * This is a list of everyone who has opened /dev/apm_bios
  94  */
  95 static DECLARE_RWSEM(user_list_lock);
  96 static LIST_HEAD(apm_user_list);
  97
  98 /*
  99  * kapmd info.  kapmd provides us a process context to handle
 100  * "APM" events within - specifically necessary if we're going
 101  * to be suspending the system.
 102  */
 103 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
 104 static DEFINE_SPINLOCK(kapmd_queue_lock);
 105 static struct apm_queue kapmd_queue;
 106
 107 static DEFINE_MUTEX(state_lock);
 108
 109 static const char driver_version[] = "1.13";    /* no spaces */
 110
 111
 112
 113 /*
 114  * Compatibility cruft until the IPAQ people move over to the new
 115  * interface.
 116  */
 117 static void __apm_get_power_status(struct apm_power_info *info)
 118 {
 119 }
 120
 121 /*
 122  * This allows machines to provide their own "apm get power status" function.
 123  */
 124 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 125 EXPORT_SYMBOL(apm_get_power_status);
 126
 127
 128 /*
 129  * APM event queue management.
 130  */
 131 static inline int queue_empty(struct apm_queue *q)
 132 {
 133         return q->event_head == q->event_tail;
 134 }
 135
 136 static inline apm_event_t queue_get_event(struct apm_queue *q)
 137 {
 138         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 139         return q->events[q->event_tail];
 140 }
 141
 142 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 143 {
 144         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 145         if (q->event_head == q->event_tail) {
 146                 static int notified;
 147
 148                 if (notified++ == 0)
 149                     printk(KERN_ERR "apm: an event queue overflowed\n");
 150                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 151         }
 152         q->events[q->event_head] = event;
 153 }
 154
 155 static void queue_event(apm_event_t event)
 156 {
 157         struct apm_user *as;
 158
 159         down_read(&user_list_lock);
 160         list_for_each_entry(as, &apm_user_list, list) {
 161                 if (as->reader)
 162                         queue_add_event(&as->queue, event);
 163         }
 164         up_read(&user_list_lock);
 165         wake_up_interruptible(&apm_waitqueue);
 166 }
 167
 168 /*
 169  * queue_suspend_event - queue an APM suspend event.
 170  *
 171  * Check that we're in a state where we can suspend.  If not,
 172  * return -EBUSY.  Otherwise, queue an event to all "writer"
 173  * users.  If there are no "writer" users, return '1' to
 174  * indicate that we can immediately suspend.
 175  */
 176 static int queue_suspend_event(apm_event_t event, struct apm_user *sender)
 177 {
 178         struct apm_user *as;
 179         int ret = 1;
 180
 181         mutex_lock(&state_lock);
 182         down_read(&user_list_lock);
 183
 184         /*
 185          * If a thread is still processing, we can't suspend, so reject
 186          * the request.
 187          */
 188         list_for_each_entry(as, &apm_user_list, list) {
 189                 if (as != sender && as->reader && as->writer && as->suser &&
 190                     as->suspend_state != SUSPEND_NONE) {
 191                         ret = -EBUSY;
 192                         goto out;
 193                 }
 194         }
 195
 196         list_for_each_entry(as, &apm_user_list, list) {
 197                 if (as != sender && as->reader && as->writer && as->suser) {
 198                         as->suspend_state = SUSPEND_PENDING;
 199                         suspends_pending++;
 200                         queue_add_event(&as->queue, event);
 201                         ret = 0;
 202                 }
 203         }
 204  out:
 205         up_read(&user_list_lock);
 206         mutex_unlock(&state_lock);
 207         wake_up_interruptible(&apm_waitqueue);
 208         return ret;
 209 }
 210
 211 static void apm_suspend(void)
 212 {
 213         struct apm_user *as;
 214         int err = pm_suspend(PM_SUSPEND_MEM);
 215
 216         /*
 217          * Anyone on the APM queues will think we're still suspended.
 218          * Send a message so everyone knows we're now awake again.
 219          */
 220         queue_event(APM_NORMAL_RESUME);
 221
 222         /*
 223          * Finally, wake up anyone who is sleeping on the suspend.
 224          */
 225         mutex_lock(&state_lock);
 226         down_read(&user_list_lock);
 227         list_for_each_entry(as, &apm_user_list, list) {
 228                 if (as->suspend_state == SUSPEND_WAIT ||
 229                     as->suspend_state == SUSPEND_ACKED) {
 230                         as->suspend_result = err;
 231                         as->suspend_state = SUSPEND_DONE;
 232                 }
 233         }
 234         up_read(&user_list_lock);
 235         mutex_unlock(&state_lock);
 236
 237         wake_up(&apm_suspend_waitqueue);
 238 }
 239
 240 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 241 {
 242         struct apm_user *as = fp->private_data;
 243         apm_event_t event;
 244         int i = count, ret = 0;
 245
 246         if (count < sizeof(apm_event_t))
 247                 return -EINVAL;
 248
 249         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 250                 return -EAGAIN;
 251
 252         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 253
 254         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 255                 event = queue_get_event(&as->queue);
 256
 257                 ret = -EFAULT;
 258                 if (copy_to_user(buf, &event, sizeof(event)))
 259                         break;
 260
 261                 mutex_lock(&state_lock);
 262                 if (as->suspend_state == SUSPEND_PENDING &&
 263                     (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND))
 264                         as->suspend_state = SUSPEND_READ;
 265                 mutex_unlock(&state_lock);
 266
 267                 buf += sizeof(event);
 268                 i -= sizeof(event);
 269         }
 270
 271         if (i < count)
 272                 ret = count - i;
 273
 274         return ret;
 275 }
 276
 277 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 278 {
 279         struct apm_user *as = fp->private_data;
 280
 281         poll_wait(fp, &apm_waitqueue, wait);
 282         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 283 }
 284
 285 /*
 286  * apm_ioctl - handle APM ioctl
 287  *
 288  * APM_IOC_SUSPEND
 289  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 290  *     - initiate a suspend
 291  *     - acknowledge a suspend read from /dev/apm_bios.
 292  *   Only when everyone who has opened /dev/apm_bios with write permission
 293  *   has acknowledge does the actual suspend happen.
 294  */
 295 static int
 296 apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
 297 {
 298         struct apm_user *as = filp->private_data;
 299         int err = -EINVAL;
 300
 301         if (!as->suser || !as->writer)
 302                 return -EPERM;
 303
 304         switch (cmd) {
 305         case APM_IOC_SUSPEND:
 306                 mutex_lock(&state_lock);
 307
 308                 as->suspend_result = -EINTR;
 309
 310                 if (as->suspend_state == SUSPEND_READ) {
 311                         int pending;
 312
 313                         /*
 314                          * If we read a suspend command from /dev/apm_bios,
 315                          * then the corresponding APM_IOC_SUSPEND ioctl is
 316                          * interpreted as an acknowledge.
 317                          */
 318                         as->suspend_state = SUSPEND_ACKED;
 319                         suspends_pending--;
 320                         pending = suspends_pending == 0;
 321                         mutex_unlock(&state_lock);
 322
 323                         /*
 324                          * If there are no further acknowledges required,
 325                          * suspend the system.
 326                          */
 327                         if (pending)
 328                                 apm_suspend();
 329
 330                         /*
 331                          * Wait for the suspend/resume to complete.  If there
 332                          * are pending acknowledges, we wait here for them.
 333                          */
 334                         freezer_do_not_count();
 335
 336                         wait_event(apm_suspend_waitqueue,
 337                                    as->suspend_state == SUSPEND_DONE);
 338
 339                         /*
 340                          * Since we are waiting until the suspend is done, the
 341                          * try_to_freeze() in freezer_count() will not trigger
 342                          */
 343                         freezer_count();
 344                 } else {
 345                         as->suspend_state = SUSPEND_WAIT;
 346                         mutex_unlock(&state_lock);
 347
 348                         /*
 349                          * Otherwise it is a request to suspend the system.
 350                          * Queue an event for all readers, and expect an
 351                          * acknowledge from all writers who haven't already
 352                          * acknowledged.
 353                          */
 354                         err = queue_suspend_event(APM_USER_SUSPEND, as);
 355                         if (err < 0) {
 356                                 /*
 357                                  * Avoid taking the lock here - this
 358                                  * should be fine.
 359                                  */
 360                                 as->suspend_state = SUSPEND_NONE;
 361                                 break;
 362                         }
 363
 364                         if (err > 0)
 365                                 apm_suspend();
 366
 367                         /*
 368                          * Wait for the suspend/resume to complete.  If there
 369                          * are pending acknowledges, we wait here for them.
 370                          */
 371                         wait_event_freezable(apm_suspend_waitqueue,
 372                                          as->suspend_state == SUSPEND_DONE);
 373                 }
 374
 375                 mutex_lock(&state_lock);
 376                 err = as->suspend_result;
 377                 as->suspend_state = SUSPEND_NONE;
 378                 mutex_unlock(&state_lock);
 379                 break;
 380         }
 381
 382         return err;
 383 }
 384
 385 static int apm_release(struct inode * inode, struct file * filp)
 386 {
 387         struct apm_user *as = filp->private_data;
 388         int pending = 0;
 389
 390         filp->private_data = NULL;
 391
 392         down_write(&user_list_lock);
 393         list_del(&as->list);
 394         up_write(&user_list_lock);
 395
 396         /*
 397          * We are now unhooked from the chain.  As far as new
 398          * events are concerned, we no longer exist.  However, we
 399          * need to balance suspends_pending, which means the
 400          * possibility of sleeping.
 401          */
 402         mutex_lock(&state_lock);
 403         if (as->suspend_state != SUSPEND_NONE) {
 404                 suspends_pending -= 1;
 405                 pending = suspends_pending == 0;
 406         }
 407         mutex_unlock(&state_lock);
 408         if (pending)
 409                 apm_suspend();
 410
 411         kfree(as);
 412         return 0;
 413 }
 414
 415 static int apm_open(struct inode * inode, struct file * filp)
 416 {
 417         struct apm_user *as;
 418
 419         as = kzalloc(sizeof(*as), GFP_KERNEL);
 420         if (as) {
 421                 /*
 422                  * XXX - this is a tiny bit broken, when we consider BSD
 423                  * process accounting. If the device is opened by root, we
 424                  * instantly flag that we used superuser privs. Who knows,
 425                  * we might close the device immediately without doing a
 426                  * privileged operation -- cevans
 427                  */
 428                 as->suser = capable(CAP_SYS_ADMIN);
 429                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 430                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 431
 432                 down_write(&user_list_lock);
 433                 list_add(&as->list, &apm_user_list);
 434                 up_write(&user_list_lock);
 435
 436                 filp->private_data = as;
 437         }
 438
 439         return as ? 0 : -ENOMEM;
 440 }
 441
 442 static struct file_operations apm_bios_fops = {
 443         .owner          = THIS_MODULE,
 444         .read           = apm_read,
 445         .poll           = apm_poll,
 446         .ioctl          = apm_ioctl,
 447         .open           = apm_open,
 448         .release        = apm_release,
 449 };
 450
 451 static struct miscdevice apm_device = {
 452         .minor          = APM_MINOR_DEV,
 453         .name           = "apm_bios",
 454         .fops           = &apm_bios_fops
 455 };
 456
 457
 458 #ifdef CONFIG_PROC_FS
 459 /*
 460  * Arguments, with symbols from linux/apm_bios.h.
 461  *
 462  *   0) Linux driver version (this will change if format changes)
 463  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 464  *   2) APM flags from APM Installation Check (0x00):
 465  *      bit 0: APM_16_BIT_SUPPORT
 466  *      bit 1: APM_32_BIT_SUPPORT
 467  *      bit 2: APM_IDLE_SLOWS_CLOCK
 468  *      bit 3: APM_BIOS_DISABLED
 469  *      bit 4: APM_BIOS_DISENGAGED
 470  *   3) AC line status
 471  *      0x00: Off-line
 472  *      0x01: On-line
 473  *      0x02: On backup power (BIOS >= 1.1 only)
 474  *      0xff: Unknown
 475  *   4) Battery status
 476  *      0x00: High
 477  *      0x01: Low
 478  *      0x02: Critical
 479  *      0x03: Charging
 480  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 481  *      0xff: Unknown
 482  *   5) Battery flag
 483  *      bit 0: High
 484  *      bit 1: Low
 485  *      bit 2: Critical
 486  *      bit 3: Charging
 487  *      bit 7: No system battery
 488  *      0xff: Unknown
 489  *   6) Remaining battery life (percentage of charge):
 490  *      0-100: valid
 491  *      -1: Unknown
 492  *   7) Remaining battery life (time units):
 493  *      Number of remaining minutes or seconds
 494  *      -1: Unknown
 495  *   8) min = minutes; sec = seconds
 496  */
 497 static int proc_apm_show(struct seq_file *m, void *v)
 498 {
 499         struct apm_power_info info;
 500         char *units;
 501
 502         info.ac_line_status = 0xff;
 503         info.battery_status = 0xff;
 504         info.battery_flag   = 0xff;
 505         info.battery_life   = -1;
 506         info.time           = -1;
 507         info.units          = -1;
 508
 509         if (apm_get_power_status)
 510                 apm_get_power_status(&info);
 511
 512         switch (info.units) {
 513         default:        units = "?";    break;
 514         case 0:         units = "min";  break;
 515         case 1:         units = "sec";  break;
 516         }
 517
 518         seq_printf(m, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 519                      driver_version, APM_32_BIT_SUPPORT,
 520                      info.ac_line_status, info.battery_status,
 521                      info.battery_flag, info.battery_life,
 522                      info.time, units);
 523
 524         return 0;
 525 }
 526
 527 static int proc_apm_open(struct inode *inode, struct file *file)
 528 {
 529         return single_open(file, proc_apm_show, NULL);
 530 }
 531
 532 static const struct file_operations apm_proc_fops = {
 533         .owner          = THIS_MODULE,
 534         .open           = proc_apm_open,
 535         .read           = seq_read,
 536         .llseek         = seq_lseek,
 537         .release        = single_release,
 538 };
 539 #endif
 540
 541 static int kapmd(void *arg)
 542 {
 543         do {
 544                 apm_event_t event;
 545                 int ret;
 546
 547                 wait_event_interruptible(kapmd_wait,
 548                                 !queue_empty(&kapmd_queue) || kthread_should_stop());
 549
 550                 if (kthread_should_stop())
 551                         break;
 552
 553                 spin_lock_irq(&kapmd_queue_lock);
 554                 event = 0;
 555                 if (!queue_empty(&kapmd_queue))
 556                         event = queue_get_event(&kapmd_queue);
 557                 spin_unlock_irq(&kapmd_queue_lock);
 558
 559                 switch (event) {
 560                 case 0:
 561                         break;
 562
 563                 case APM_LOW_BATTERY:
 564                 case APM_POWER_STATUS_CHANGE:
 565                         queue_event(event);
 566                         break;
 567
 568                 case APM_USER_SUSPEND:
 569                 case APM_SYS_SUSPEND:
 570                         ret = queue_suspend_event(event, NULL);
 571                         if (ret < 0) {
 572                                 /*
 573                                  * We were busy.  Try again in 50ms.
 574                                  */
 575                                 queue_add_event(&kapmd_queue, event);
 576                                 msleep(50);
 577                         }
 578                         if (ret > 0)
 579                                 apm_suspend();
 580                         break;
 581
 582                 case APM_CRITICAL_SUSPEND:
 583                         apm_suspend();
 584                         break;
 585                 }
 586         } while (1);
 587
 588         return 0;
 589 }
 590
 591 static int __init apm_init(void)
 592 {
 593         int ret;
 594
 595         if (apm_disabled) {
 596                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 597                 return -ENODEV;
 598         }
 599
 600         kapmd_tsk = kthread_create(kapmd, NULL, "kapmd");
 601         if (IS_ERR(kapmd_tsk)) {
 602                 ret = PTR_ERR(kapmd_tsk);
 603                 kapmd_tsk = NULL;
 604                 return ret;
 605         }
 606         wake_up_process(kapmd_tsk);
 607
 608 #ifdef CONFIG_PROC_FS
 609         proc_create("apm", 0, NULL, &apm_proc_fops);
 610 #endif
 611
 612         ret = misc_register(&apm_device);
 613         if (ret != 0) {
 614                 remove_proc_entry("apm", NULL);
 615                 kthread_stop(kapmd_tsk);
 616         }
 617
 618         return ret;
 619 }
 620
 621 static void __exit apm_exit(void)
 622 {
 623         misc_deregister(&apm_device);
 624         remove_proc_entry("apm", NULL);
 625
 626         kthread_stop(kapmd_tsk);
 627 }
 628
 629 module_init(apm_init);
 630 module_exit(apm_exit);
 631
 632 MODULE_AUTHOR("Stephen Rothwell");
 633 MODULE_DESCRIPTION("Advanced Power Management");
 634 MODULE_LICENSE("GPL");
 635
 636 #ifndef MODULE
 637 static int __init apm_setup(char *str)
 638 {
 639         while ((str != NULL) && (*str != '\0')) {
 640                 if (strncmp(str, "off", 3) == 0)
 641                         apm_disabled = 1;
 642                 if (strncmp(str, "on", 2) == 0)
 643                         apm_disabled = 0;
 644                 str = strchr(str, ',');
 645                 if (str != NULL)
 646                         str += strspn(str, ", \t");
 647         }
 648         return 1;
 649 }
 650
 651 __setup("apm=", apm_setup);
 652 #endif
 653
 654 /**
 655  * apm_queue_event - queue an APM event for kapmd
 656  * @event: APM event
 657  *
 658  * Queue an APM event for kapmd to process and ultimately take the
 659  * appropriate action.  Only a subset of events are handled:
 660  *   %APM_LOW_BATTERY
 661  *   %APM_POWER_STATUS_CHANGE
 662  *   %APM_USER_SUSPEND
 663  *   %APM_SYS_SUSPEND
 664  *   %APM_CRITICAL_SUSPEND
 665  */
 666 void apm_queue_event(apm_event_t event)
 667 {
 668         unsigned long flags;
 669
 670         spin_lock_irqsave(&kapmd_queue_lock, flags);
 671         queue_add_event(&kapmd_queue, event);
 672         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 673
 674         wake_up_interruptible(&kapmd_wait);
 675 }
 676 EXPORT_SYMBOL(apm_queue_event);