arch/sh/kernel/apm.c

   1 /*
   2  * bios-less APM driver for hp680
   3  *
   4  * Copyright 2005 (c) Andriy Skulysh <askulysh@gmail.com>
   5  *
   6  * based on ARM APM driver by
   7  *  Jamey Hicks <jamey@crl.dec.com>
   8  *
   9  * adapted from the APM BIOS driver for Linux by
  10  *  Stephen Rothwell (sfr@linuxcare.com)
  11  *
  12  * APM 1.2 Reference:
  13  *   Intel Corporation, Microsoft Corporation. Advanced Power Management
  14  *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
  15  *
  16  * [This document is available from Microsoft at:
  17  *    http://www.microsoft.com/hwdev/busbios/amp_12.htm]
  18  */
  19 #include <linux/module.h>
  20 #include <linux/poll.h>
  21 #include <linux/timer.h>
  22 #include <linux/slab.h>
  23 #include <linux/proc_fs.h>
  24 #include <linux/miscdevice.h>
  25 #include <linux/apm_bios.h>
  26 #include <linux/pm.h>
  27 #include <linux/pm_legacy.h>
  28 #include <asm/apm.h>
  29
  30 #define MODNAME "apm"
  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  * Maximum number of events stored
  40  */
  41 #define APM_MAX_EVENTS                  16
  42
  43 struct apm_queue {
  44         unsigned int            event_head;
  45         unsigned int            event_tail;
  46         apm_event_t             events[APM_MAX_EVENTS];
  47 };
  48
  49 /*
  50  * The per-file APM data
  51  */
  52 struct apm_user {
  53         struct list_head        list;
  54
  55         unsigned int            suser: 1;
  56         unsigned int            writer: 1;
  57         unsigned int            reader: 1;
  58
  59         int                     suspend_result;
  60         unsigned int            suspend_state;
  61 #define SUSPEND_NONE    0               /* no suspend pending */
  62 #define SUSPEND_PENDING 1               /* suspend pending read */
  63 #define SUSPEND_READ    2               /* suspend read, pending ack */
  64 #define SUSPEND_ACKED   3               /* suspend acked */
  65 #define SUSPEND_DONE    4               /* suspend completed */
  66
  67         struct apm_queue        queue;
  68 };
  69
  70 /*
  71  * Local variables
  72  */
  73 static int suspends_pending;
  74
  75 static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
  76 static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
  77
  78 /*
  79  * This is a list of everyone who has opened /dev/apm_bios
  80  */
  81 static DECLARE_RWSEM(user_list_lock);
  82 static LIST_HEAD(apm_user_list);
  83
  84 /*
  85  * kapmd info.  kapmd provides us a process context to handle
  86  * "APM" events within - specifically necessary if we're going
  87  * to be suspending the system.
  88  */
  89 static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
  90 static DECLARE_COMPLETION(kapmd_exit);
  91 static DEFINE_SPINLOCK(kapmd_queue_lock);
  92 static struct apm_queue kapmd_queue;
  93
  94 int apm_suspended;
  95 EXPORT_SYMBOL(apm_suspended);
  96
  97 /* Platform-specific apm_read_proc(). */
  98 int (*apm_get_info)(char *buf, char **start, off_t fpos, int length);
  99 EXPORT_SYMBOL(apm_get_info);
 100
 101 /*
 102  * APM event queue management.
 103  */
 104 static inline int queue_empty(struct apm_queue *q)
 105 {
 106         return q->event_head == q->event_tail;
 107 }
 108
 109 static inline apm_event_t queue_get_event(struct apm_queue *q)
 110 {
 111         q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 112         return q->events[q->event_tail];
 113 }
 114
 115 static void queue_add_event(struct apm_queue *q, apm_event_t event)
 116 {
 117         q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
 118         if (q->event_head == q->event_tail) {
 119                 static int notified;
 120
 121                 if (notified++ == 0)
 122                         printk(KERN_ERR "apm: an event queue overflowed\n");
 123
 124                 q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
 125         }
 126         q->events[q->event_head] = event;
 127 }
 128
 129 static void queue_event_one_user(struct apm_user *as, apm_event_t event)
 130 {
 131         if (as->suser && as->writer) {
 132                 switch (event) {
 133                 case APM_SYS_SUSPEND:
 134                 case APM_USER_SUSPEND:
 135                         /*
 136                          * If this user already has a suspend pending,
 137                          * don't queue another one.
 138                          */
 139                         if (as->suspend_state != SUSPEND_NONE)
 140                                 return;
 141
 142                         as->suspend_state = SUSPEND_PENDING;
 143                         suspends_pending++;
 144                         break;
 145                 }
 146         }
 147         queue_add_event(&as->queue, event);
 148 }
 149
 150 static void queue_event(apm_event_t event, struct apm_user *sender)
 151 {
 152         struct apm_user *as;
 153
 154         down_read(&user_list_lock);
 155
 156         list_for_each_entry(as, &apm_user_list, list)
 157                 if (as != sender && as->reader)
 158                         queue_event_one_user(as, event);
 159
 160         up_read(&user_list_lock);
 161         wake_up_interruptible(&apm_waitqueue);
 162 }
 163
 164 /**
 165  * apm_queue_event - queue an APM event for kapmd
 166  * @event: APM event
 167  *
 168  * Queue an APM event for kapmd to process and ultimately take the
 169  * appropriate action.  Only a subset of events are handled:
 170  *   %APM_LOW_BATTERY
 171  *   %APM_POWER_STATUS_CHANGE
 172  *   %APM_USER_SUSPEND
 173  *   %APM_SYS_SUSPEND
 174  *   %APM_CRITICAL_SUSPEND
 175  */
 176 void apm_queue_event(apm_event_t event)
 177 {
 178         spin_lock_irq(&kapmd_queue_lock);
 179         queue_add_event(&kapmd_queue, event);
 180         spin_unlock_irq(&kapmd_queue_lock);
 181
 182         wake_up_interruptible(&kapmd_wait);
 183 }
 184 EXPORT_SYMBOL(apm_queue_event);
 185
 186 static void apm_suspend(void)
 187 {
 188         struct apm_user *as;
 189         int err;
 190
 191         apm_suspended = 1;
 192         err = pm_suspend(PM_SUSPEND_MEM);
 193
 194         /*
 195          * Anyone on the APM queues will think we're still suspended.
 196          * Send a message so everyone knows we're now awake again.
 197          */
 198         queue_event(APM_NORMAL_RESUME, NULL);
 199
 200         /*
 201          * Finally, wake up anyone who is sleeping on the suspend.
 202          */
 203         down_read(&user_list_lock);
 204         list_for_each_entry(as, &apm_user_list, list) {
 205                 as->suspend_result = err;
 206                 as->suspend_state = SUSPEND_DONE;
 207         }
 208         up_read(&user_list_lock);
 209
 210         wake_up(&apm_suspend_waitqueue);
 211         apm_suspended = 0;
 212 }
 213
 214 static ssize_t apm_read(struct file *fp, char __user *buf,
 215                         size_t count, loff_t *ppos)
 216 {
 217         struct apm_user *as = fp->private_data;
 218         apm_event_t event;
 219         int i = count, ret = 0;
 220
 221         if (count < sizeof(apm_event_t))
 222                 return -EINVAL;
 223
 224         if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
 225                 return -EAGAIN;
 226
 227         wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
 228
 229         while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
 230                 event = queue_get_event(&as->queue);
 231
 232                 ret = -EFAULT;
 233                 if (copy_to_user(buf, &event, sizeof(event)))
 234                         break;
 235
 236                 if (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)
 237                         as->suspend_state = SUSPEND_READ;
 238
 239                 buf += sizeof(event);
 240                 i -= sizeof(event);
 241         }
 242
 243         if (i < count)
 244                 ret = count - i;
 245
 246         return ret;
 247 }
 248
 249 static unsigned int apm_poll(struct file *fp, poll_table * wait)
 250 {
 251         struct apm_user *as = fp->private_data;
 252
 253         poll_wait(fp, &apm_waitqueue, wait);
 254         return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
 255 }
 256
 257 /*
 258  * apm_ioctl - handle APM ioctl
 259  *
 260  * APM_IOC_SUSPEND
 261  *   This IOCTL is overloaded, and performs two functions.  It is used to:
 262  *     - initiate a suspend
 263  *     - acknowledge a suspend read from /dev/apm_bios.
 264  *   Only when everyone who has opened /dev/apm_bios with write permission
 265  *   has acknowledge does the actual suspend happen.
 266  */
 267 static int
 268 apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
 269 {
 270         struct apm_user *as = filp->private_data;
 271         unsigned long flags;
 272         int err = -EINVAL;
 273
 274         if (!as->suser || !as->writer)
 275                 return -EPERM;
 276
 277         switch (cmd) {
 278         case APM_IOC_SUSPEND:
 279                 as->suspend_result = -EINTR;
 280
 281                 if (as->suspend_state == SUSPEND_READ) {
 282                         /*
 283                          * If we read a suspend command from /dev/apm_bios,
 284                          * then the corresponding APM_IOC_SUSPEND ioctl is
 285                          * interpreted as an acknowledge.
 286                          */
 287                         as->suspend_state = SUSPEND_ACKED;
 288                         suspends_pending--;
 289                 } else {
 290                         /*
 291                          * Otherwise it is a request to suspend the system.
 292                          * Queue an event for all readers, and expect an
 293                          * acknowledge from all writers who haven't already
 294                          * acknowledged.
 295                          */
 296                         queue_event(APM_USER_SUSPEND, as);
 297                 }
 298
 299                 /*
 300                  * If there are no further acknowledges required, suspend
 301                  * the system.
 302                  */
 303                 if (suspends_pending == 0)
 304                         apm_suspend();
 305
 306                 /*
 307                  * Wait for the suspend/resume to complete.  If there are
 308                  * pending acknowledges, we wait here for them.
 309                  *
 310                  * Note that we need to ensure that the PM subsystem does
 311                  * not kick us out of the wait when it suspends the threads.
 312                  */
 313                 flags = current->flags;
 314                 current->flags |= PF_NOFREEZE;
 315
 316                 /*
 317                  * Note: do not allow a thread which is acking the suspend
 318                  * to escape until the resume is complete.
 319                  */
 320                 if (as->suspend_state == SUSPEND_ACKED)
 321                         wait_event(apm_suspend_waitqueue,
 322                                          as->suspend_state == SUSPEND_DONE);
 323                 else
 324                         wait_event_interruptible(apm_suspend_waitqueue,
 325                                          as->suspend_state == SUSPEND_DONE);
 326
 327                 current->flags = flags;
 328                 err = as->suspend_result;
 329                 as->suspend_state = SUSPEND_NONE;
 330                 break;
 331         }
 332
 333         return err;
 334 }
 335
 336 static int apm_release(struct inode * inode, struct file * filp)
 337 {
 338         struct apm_user *as = filp->private_data;
 339         filp->private_data = NULL;
 340
 341         down_write(&user_list_lock);
 342         list_del(&as->list);
 343         up_write(&user_list_lock);
 344
 345         /*
 346          * We are now unhooked from the chain.  As far as new
 347          * events are concerned, we no longer exist.  However, we
 348          * need to balance suspends_pending, which means the
 349          * possibility of sleeping.
 350          */
 351         if (as->suspend_state != SUSPEND_NONE) {
 352                 suspends_pending -= 1;
 353                 if (suspends_pending == 0)
 354                         apm_suspend();
 355         }
 356
 357         kfree(as);
 358         return 0;
 359 }
 360
 361 static int apm_open(struct inode * inode, struct file * filp)
 362 {
 363         struct apm_user *as;
 364
 365         as = kzalloc(sizeof(*as), GFP_KERNEL);
 366         if (as) {
 367                 /*
 368                  * XXX - this is a tiny bit broken, when we consider BSD
 369                  * process accounting. If the device is opened by root, we
 370                  * instantly flag that we used superuser privs. Who knows,
 371                  * we might close the device immediately without doing a
 372                  * privileged operation -- cevans
 373                  */
 374                 as->suser = capable(CAP_SYS_ADMIN);
 375                 as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
 376                 as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
 377
 378                 down_write(&user_list_lock);
 379                 list_add(&as->list, &apm_user_list);
 380                 up_write(&user_list_lock);
 381
 382                 filp->private_data = as;
 383         }
 384
 385         return as ? 0 : -ENOMEM;
 386 }
 387
 388 static struct file_operations apm_bios_fops = {
 389         .owner          = THIS_MODULE,
 390         .read           = apm_read,
 391         .poll           = apm_poll,
 392         .ioctl          = apm_ioctl,
 393         .open           = apm_open,
 394         .release        = apm_release,
 395 };
 396
 397 static struct miscdevice apm_device = {
 398         .minor          = APM_MINOR_DEV,
 399         .name           = "apm_bios",
 400         .fops           = &apm_bios_fops
 401 };
 402
 403
 404 #ifdef CONFIG_PROC_FS
 405 /*
 406  * Arguments, with symbols from linux/apm_bios.h.
 407  *
 408  *   0) Linux driver version (this will change if format changes)
 409  *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
 410  *   2) APM flags from APM Installation Check (0x00):
 411  *      bit 0: APM_16_BIT_SUPPORT
 412  *      bit 1: APM_32_BIT_SUPPORT
 413  *      bit 2: APM_IDLE_SLOWS_CLOCK
 414  *      bit 3: APM_BIOS_DISABLED
 415  *      bit 4: APM_BIOS_DISENGAGED
 416  *   3) AC line status
 417  *      0x00: Off-line
 418  *      0x01: On-line
 419  *      0x02: On backup power (BIOS >= 1.1 only)
 420  *      0xff: Unknown
 421  *   4) Battery status
 422  *      0x00: High
 423  *      0x01: Low
 424  *      0x02: Critical
 425  *      0x03: Charging
 426  *      0x04: Selected battery not present (BIOS >= 1.2 only)
 427  *      0xff: Unknown
 428  *   5) Battery flag
 429  *      bit 0: High
 430  *      bit 1: Low
 431  *      bit 2: Critical
 432  *      bit 3: Charging
 433  *      bit 7: No system battery
 434  *      0xff: Unknown
 435  *   6) Remaining battery life (percentage of charge):
 436  *      0-100: valid
 437  *      -1: Unknown
 438  *   7) Remaining battery life (time units):
 439  *      Number of remaining minutes or seconds
 440  *      -1: Unknown
 441  *   8) min = minutes; sec = seconds
 442  */
 443 static int apm_read_proc(char *buf, char **start, off_t fpos, int length)
 444 {
 445         if (likely(apm_get_info))
 446                 return apm_get_info(buf, start, fpos, length);
 447
 448         return -EINVAL;
 449 }
 450 #endif
 451
 452 static int kapmd(void *arg)
 453 {
 454         daemonize("kapmd");
 455         current->flags |= PF_NOFREEZE;
 456
 457         do {
 458                 apm_event_t event;
 459
 460                 wait_event_interruptible(kapmd_wait,
 461                                 !queue_empty(&kapmd_queue) || !pm_active);
 462
 463                 if (!pm_active)
 464                         break;
 465
 466                 spin_lock_irq(&kapmd_queue_lock);
 467                 event = 0;
 468                 if (!queue_empty(&kapmd_queue))
 469                         event = queue_get_event(&kapmd_queue);
 470                 spin_unlock_irq(&kapmd_queue_lock);
 471
 472                 switch (event) {
 473                 case 0:
 474                         break;
 475
 476                 case APM_LOW_BATTERY:
 477                 case APM_POWER_STATUS_CHANGE:
 478                         queue_event(event, NULL);
 479                         break;
 480
 481                 case APM_USER_SUSPEND:
 482                 case APM_SYS_SUSPEND:
 483                         queue_event(event, NULL);
 484                         if (suspends_pending == 0)
 485                                 apm_suspend();
 486                         break;
 487
 488                 case APM_CRITICAL_SUSPEND:
 489                         apm_suspend();
 490                         break;
 491                 }
 492         } while (1);
 493
 494         complete_and_exit(&kapmd_exit, 0);
 495 }
 496
 497 static int __init apm_init(void)
 498 {
 499         int ret;
 500
 501         pm_active = 1;
 502
 503         ret = kernel_thread(kapmd, NULL, CLONE_KERNEL);
 504         if (unlikely(ret < 0)) {
 505                 pm_active = 0;
 506                 return ret;
 507         }
 508
 509         create_proc_info_entry("apm", 0, NULL, apm_read_proc);
 510
 511         ret = misc_register(&apm_device);
 512         if (unlikely(ret != 0)) {
 513                 remove_proc_entry("apm", NULL);
 514
 515                 pm_active = 0;
 516                 wake_up(&kapmd_wait);
 517                 wait_for_completion(&kapmd_exit);
 518         }
 519
 520         return ret;
 521 }
 522
 523 static void __exit apm_exit(void)
 524 {
 525         misc_deregister(&apm_device);
 526         remove_proc_entry("apm", NULL);
 527
 528         pm_active = 0;
 529         wake_up(&kapmd_wait);
 530         wait_for_completion(&kapmd_exit);
 531 }
 532
 533 module_init(apm_init);
 534 module_exit(apm_exit);
 535
 536 MODULE_AUTHOR("Stephen Rothwell, Andriy Skulysh");
 537 MODULE_DESCRIPTION("Advanced Power Management");
 538 MODULE_LICENSE("GPL");