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