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