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/config.h>
  14 #include <linux/module.h>
  15 #include <linux/poll.h>
  16 #include <linux/timer.h>
  17 #include <linux/slab.h>
  18 #include <linux/proc_fs.h>
  19 #include <linux/miscdevice.h>
  20 #include <linux/apm_bios.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
  84 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
  85 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
  86
  87 /*
  88  * This is a list of everyone who has opened /dev/apm_bios
  89  */
  90 static DECLARE_RWSEM(user_list_lock);
  91 static LIST_HEAD(apm_user_list);
  92
  93 /*
  94  * kapmd info.  kapmd provides us a process context to handle
  95  * "APM" events within - specifically necessary if we're going
  96  * to be suspending the system.
  97  */
  98 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
  99 static DECLARE_COMPLETION(kapmd_exit);
 100 static DEFINE_SPINLOCK(kapmd_queue_lock);
 101 static struct apm_queue kapmd_queue;
 102
 103
 104 static const char driver_version[] = "1.13";    /* no spaces */
 105
 106
 107
 108 /*
 109  * Compatibility cruft until the IPAQ people move over to the new
 110  * interface.
 111  */
 112 static void __apm_get_power_status(struct apm_power_info *info)
 113 {
 114 }
 115
 116 /*
 117  * This allows machines to provide their own "apm get power status" function.
 118  */
 119 void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
 120 EXPORT_SYMBOL(apm_get_power_status);
 121
 122
 123 /*
 124  * APM event queue management.
 125  */
 126 static inline int queue_empty(struct apm_queue *q)
 127 {
 128         return q->event_head == q->event_tail;
 129 }
 130
 131 static inline apm_event_t queue_get_event(struct apm_queue *q)
 132 {
 133         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 134         return q->events[q->event_tail];
 135 }
 136
 137 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 138 {
 139         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 140         if (q->event_head == q->event_tail) {
 141                 static int notified;
 142
 143                 if (notified++ == 0)
 144                     printk(KERN_ERR "apm: an event queue overflowed\n");
 145                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 146         }
 147         q->events[q->event_head] = event;
 148 }
 149
 150 static void queue_event_one_user(struct apm_user *as, apm_event_t event)
 151 {
 152         if (as->suser && as->writer) {
 153                 switch (event) {
 154                 case APM_SYS_SUSPEND:
 155                 case APM_USER_SUSPEND:
 156                         /*
 157                          * If this user already has a suspend pending,
 158                          * don't queue another one.
 159                          */
 160                         if (as->suspend_state != SUSPEND_NONE)
 161                                 return;
 162
 163                         as->suspend_state = SUSPEND_PENDING;
 164                         suspends_pending++;
 165                         break;
 166                 }
 167         }
 168         queue_add_event(&as->queue, event);
 169 }
 170
 171 static void queue_event(apm_event_t event, struct apm_user *sender)
 172 {
 173         struct apm_user *as;
 174
 175         down_read(&user_list_lock);
 176         list_for_each_entry(as, &apm_user_list, list) {
 177                 if (as != sender && as->reader)
 178                         queue_event_one_user(as, event);
 179         }
 180         up_read(&user_list_lock);
 181         wake_up_interruptible(&apm_waitqueue);
 182 }
 183
 184 static void apm_suspend(void)
 185 {
 186         struct apm_user *as;
 187         int err = pm_suspend(PM_SUSPEND_MEM);
 188
 189         /*
 190          * Anyone on the APM queues will think we're still suspended.
 191          * Send a message so everyone knows we're now awake again.
 192          */
 193         queue_event(APM_NORMAL_RESUME, NULL);
 194
 195         /*
 196          * Finally, wake up anyone who is sleeping on the suspend.
 197          */
 198         down_read(&user_list_lock);
 199         list_for_each_entry(as, &apm_user_list, list) {
 200                 as->suspend_result = err;
 201                 as->suspend_state = SUSPEND_DONE;
 202         }
 203         up_read(&user_list_lock);
 204
 205         wake_up(&apm_suspend_waitqueue);
 206 }
 207
 208 static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
 209 {
 210         struct apm_user *as = fp->private_data;
 211         apm_event_t event;
 212         int i = count, ret = 0;
 213
 214         if (count < sizeof(apm_event_t))
 215                 return -EINVAL;
 216
 217         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 218                 return -EAGAIN;
 219
 220         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 221
 222         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 223                 event = queue_get_event(&as->queue);
 224
 225                 ret = -EFAULT;
 226                 if (copy_to_user(buf, &event, sizeof(event)))
 227                         break;
 228
 229                 if (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)
 230                         as->suspend_state = SUSPEND_READ;
 231
 232                 buf += sizeof(event);
 233                 i -= sizeof(event);
 234         }
 235
 236         if (i < count)
 237                 ret = count - i;
 238
 239         return ret;
 240 }
 241
 242 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 243 {
 244         struct apm_user *as = fp->private_data;
 245
 246         poll_wait(fp, &apm_waitqueue, wait);
 247         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 248 }
 249
 250 /*
 251  * apm_ioctl - handle APM ioctl
 252  *
 253  * APM_IOC_SUSPEND
 254  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 255  *     - initiate a suspend
 256  *     - acknowledge a suspend read from /dev/apm_bios.
 257  *   Only when everyone who has opened /dev/apm_bios with write permission
 258  *   has acknowledge does the actual suspend happen.
 259  */
 260 static int
 261 apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
 262 {
 263         struct apm_user *as = filp->private_data;
 264         unsigned long flags;
 265         int err = -EINVAL;
 266
 267         if (!as->suser || !as->writer)
 268                 return -EPERM;
 269
 270         switch (cmd) {
 271         case APM_IOC_SUSPEND:
 272                 as->suspend_result = -EINTR;
 273
 274                 if (as->suspend_state == SUSPEND_READ) {
 275                         /*
 276                          * If we read a suspend command from /dev/apm_bios,
 277                          * then the corresponding APM_IOC_SUSPEND ioctl is
 278                          * interpreted as an acknowledge.
 279                          */
 280                         as->suspend_state = SUSPEND_ACKED;
 281                         suspends_pending--;
 282                 } else {
 283                         /*
 284                          * Otherwise it is a request to suspend the system.
 285                          * Queue an event for all readers, and expect an
 286                          * acknowledge from all writers who haven't already
 287                          * acknowledged.
 288                          */
 289                         queue_event(APM_USER_SUSPEND, as);
 290                 }
 291
 292                 /*
 293                  * If there are no further acknowledges required, suspend
 294                  * the system.
 295                  */
 296                 if (suspends_pending == 0)
 297                         apm_suspend();
 298
 299                 /*
 300                  * Wait for the suspend/resume to complete.  If there are
 301                  * pending acknowledges, we wait here for them.
 302                  *
 303                  * Note that we need to ensure that the PM subsystem does
 304                  * not kick us out of the wait when it suspends the threads.
 305                  */
 306                 flags = current->flags;
 307                 current->flags |= PF_NOFREEZE;
 308
 309                 /*
 310                  * Note: do not allow a thread which is acking the suspend
 311                  * to escape until the resume is complete.
 312                  */
 313                 if (as->suspend_state == SUSPEND_ACKED)
 314                         wait_event(apm_suspend_waitqueue,
 315                                          as->suspend_state == SUSPEND_DONE);
 316                 else
 317                         wait_event_interruptible(apm_suspend_waitqueue,
 318                                          as->suspend_state == SUSPEND_DONE);
 319
 320                 current->flags = flags;
 321                 err = as->suspend_result;
 322                 as->suspend_state = SUSPEND_NONE;
 323                 break;
 324         }
 325
 326         return err;
 327 }
 328
 329 static int apm_release(struct inode * inode, struct file * filp)
 330 {
 331         struct apm_user *as = filp->private_data;
 332         filp->private_data = NULL;
 333
 334         down_write(&user_list_lock);
 335         list_del(&as->list);
 336         up_write(&user_list_lock);
 337
 338         /*
 339          * We are now unhooked from the chain.  As far as new
 340          * events are concerned, we no longer exist.  However, we
 341          * need to balance suspends_pending, which means the
 342          * possibility of sleeping.
 343          */
 344         if (as->suspend_state != SUSPEND_NONE) {
 345                 suspends_pending -= 1;
 346                 if (suspends_pending == 0)
 347                         apm_suspend();
 348         }
 349
 350         kfree(as);
 351         return 0;
 352 }
 353
 354 static int apm_open(struct inode * inode, struct file * filp)
 355 {
 356         struct apm_user *as;
 357
 358         as = (struct apm_user *)kmalloc(sizeof(*as), GFP_KERNEL);
 359         if (as) {
 360                 memset(as, 0, sizeof(*as));
 361
 362                 /*
 363                  * XXX - this is a tiny bit broken, when we consider BSD
 364                  * process accounting. If the device is opened by root, we
 365                  * instantly flag that we used superuser privs. Who knows,
 366                  * we might close the device immediately without doing a
 367                  * privileged operation -- cevans
 368                  */
 369                 as->suser = capable(CAP_SYS_ADMIN);
 370                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 371                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 372
 373                 down_write(&user_list_lock);
 374                 list_add(&as->list, &apm_user_list);
 375                 up_write(&user_list_lock);
 376
 377                 filp->private_data = as;
 378         }
 379
 380         return as ? 0 : -ENOMEM;
 381 }
 382
 383 static struct file_operations apm_bios_fops = {
 384         .owner          = THIS_MODULE,
 385         .read           = apm_read,
 386         .poll           = apm_poll,
 387         .ioctl          = apm_ioctl,
 388         .open           = apm_open,
 389         .release        = apm_release,
 390 };
 391
 392 static struct miscdevice apm_device = {
 393         .minor          = APM_MINOR_DEV,
 394         .name           = "apm_bios",
 395         .fops           = &apm_bios_fops
 396 };
 397
 398
 399 #ifdef CONFIG_PROC_FS
 400 /*
 401  * Arguments, with symbols from linux/apm_bios.h.
 402  *
 403  *   0) Linux driver version (this will change if format changes)
 404  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 405  *   2) APM flags from APM Installation Check (0x00):
 406  *      bit 0: APM_16_BIT_SUPPORT
 407  *      bit 1: APM_32_BIT_SUPPORT
 408  *      bit 2: APM_IDLE_SLOWS_CLOCK
 409  *      bit 3: APM_BIOS_DISABLED
 410  *      bit 4: APM_BIOS_DISENGAGED
 411  *   3) AC line status
 412  *      0x00: Off-line
 413  *      0x01: On-line
 414  *      0x02: On backup power (BIOS >= 1.1 only)
 415  *      0xff: Unknown
 416  *   4) Battery status
 417  *      0x00: High
 418  *      0x01: Low
 419  *      0x02: Critical
 420  *      0x03: Charging
 421  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 422  *      0xff: Unknown
 423  *   5) Battery flag
 424  *      bit 0: High
 425  *      bit 1: Low
 426  *      bit 2: Critical
 427  *      bit 3: Charging
 428  *      bit 7: No system battery
 429  *      0xff: Unknown
 430  *   6) Remaining battery life (percentage of charge):
 431  *      0-100: valid
 432  *      -1: Unknown
 433  *   7) Remaining battery life (time units):
 434  *      Number of remaining minutes or seconds
 435  *      -1: Unknown
 436  *   8) min = minutes; sec = seconds
 437  */
 438 static int apm_get_info(char *buf, char **start, off_t fpos, int length)
 439 {
 440         struct apm_power_info info;
 441         char *units;
 442         int ret;
 443
 444         info.ac_line_status = 0xff;
 445         info.battery_status = 0xff;
 446         info.battery_flag   = 0xff;
 447         info.battery_life   = -1;
 448         info.time           = -1;
 449         info.units          = -1;
 450
 451         if (apm_get_power_status)
 452                 apm_get_power_status(&info);
 453
 454         switch (info.units) {
 455         default:        units = "?";    break;
 456         case 0:         units = "min";  break;
 457         case 1:         units = "sec";  break;
 458         }
 459
 460         ret = sprintf(buf, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
 461                      driver_version, APM_32_BIT_SUPPORT,
 462                      info.ac_line_status, info.battery_status,
 463                      info.battery_flag, info.battery_life,
 464                      info.time, units);
 465
 466         return ret;
 467 }
 468 #endif
 469
 470 static int kapmd(void *arg)
 471 {
 472         daemonize("kapmd");
 473         current->flags |= PF_NOFREEZE;
 474
 475         do {
 476                 apm_event_t event;
 477
 478                 wait_event_interruptible(kapmd_wait,
 479                                 !queue_empty(&kapmd_queue) || !pm_active);
 480
 481                 if (!pm_active)
 482                         break;
 483
 484                 spin_lock_irq(&kapmd_queue_lock);
 485                 event = 0;
 486                 if (!queue_empty(&kapmd_queue))
 487                         event = queue_get_event(&kapmd_queue);
 488                 spin_unlock_irq(&kapmd_queue_lock);
 489
 490                 switch (event) {
 491                 case 0:
 492                         break;
 493
 494                 case APM_LOW_BATTERY:
 495                 case APM_POWER_STATUS_CHANGE:
 496                         queue_event(event, NULL);
 497                         break;
 498
 499                 case APM_USER_SUSPEND:
 500                 case APM_SYS_SUSPEND:
 501                         queue_event(event, NULL);
 502                         if (suspends_pending == 0)
 503                                 apm_suspend();
 504                         break;
 505
 506                 case APM_CRITICAL_SUSPEND:
 507                         apm_suspend();
 508                         break;
 509                 }
 510         } while (1);
 511
 512         complete_and_exit(&kapmd_exit, 0);
 513 }
 514
 515 static int __init apm_init(void)
 516 {
 517         int ret;
 518
 519         if (apm_disabled) {
 520                 printk(KERN_NOTICE "apm: disabled on user request.\n");
 521                 return -ENODEV;
 522         }
 523
 524         if (PM_IS_ACTIVE()) {
 525                 printk(KERN_NOTICE "apm: overridden by ACPI.\n");
 526                 return -EINVAL;
 527         }
 528
 529         pm_active = 1;
 530
 531         ret = kernel_thread(kapmd, NULL, CLONE_KERNEL);
 532         if (ret < 0) {
 533                 pm_active = 0;
 534                 return ret;
 535         }
 536
 537 #ifdef CONFIG_PROC_FS
 538         create_proc_info_entry("apm", 0, NULL, apm_get_info);
 539 #endif
 540
 541         ret = misc_register(&apm_device);
 542         if (ret != 0) {
 543                 remove_proc_entry("apm", NULL);
 544
 545                 pm_active = 0;
 546                 wake_up(&kapmd_wait);
 547                 wait_for_completion(&kapmd_exit);
 548         }
 549
 550         return ret;
 551 }
 552
 553 static void __exit apm_exit(void)
 554 {
 555         misc_deregister(&apm_device);
 556         remove_proc_entry("apm", NULL);
 557
 558         pm_active = 0;
 559         wake_up(&kapmd_wait);
 560         wait_for_completion(&kapmd_exit);
 561 }
 562
 563 module_init(apm_init);
 564 module_exit(apm_exit);
 565
 566 MODULE_AUTHOR("Stephen Rothwell");
 567 MODULE_DESCRIPTION("Advanced Power Management");
 568 MODULE_LICENSE("GPL");
 569
 570 #ifndef MODULE
 571 static int __init apm_setup(char *str)
 572 {
 573         while ((str != NULL) && (*str != '\0')) {
 574                 if (strncmp(str, "off", 3) == 0)
 575                         apm_disabled = 1;
 576                 if (strncmp(str, "on", 2) == 0)
 577                         apm_disabled = 0;
 578                 str = strchr(str, ',');
 579                 if (str != NULL)
 580                         str += strspn(str, ", \t");
 581         }
 582         return 1;
 583 }
 584
 585 __setup("apm=", apm_setup);
 586 #endif
 587
 588 /**
 589  * apm_queue_event - queue an APM event for kapmd
 590  * @event: APM event
 591  *
 592  * Queue an APM event for kapmd to process and ultimately take the
 593  * appropriate action.  Only a subset of events are handled:
 594  *   %APM_LOW_BATTERY
 595  *   %APM_POWER_STATUS_CHANGE
 596  *   %APM_USER_SUSPEND
 597  *   %APM_SYS_SUSPEND
 598  *   %APM_CRITICAL_SUSPEND
 599  */
 600 void apm_queue_event(apm_event_t event)
 601 {
 602         unsigned long flags;
 603
 604         spin_lock_irqsave(&kapmd_queue_lock, flags);
 605         queue_add_event(&kapmd_queue, event);
 606         spin_unlock_irqrestore(&kapmd_queue_lock, flags);
 607
 608         wake_up_interruptible(&kapmd_wait);
 609 }
 610 EXPORT_SYMBOL(apm_queue_event);