drivers/acpi/sleep/main.c

   1 /*
   2  * sleep.c - ACPI sleep support.
   3  *
   4  * Copyright (c) 2005 Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
   5  * Copyright (c) 2004 David Shaohua Li <shaohua.li@intel.com>
   6  * Copyright (c) 2000-2003 Patrick Mochel
   7  * Copyright (c) 2003 Open Source Development Lab
   8  *
   9  * This file is released under the GPLv2.
  10  *
  11  */
  12
  13 #include <linux/delay.h>
  14 #include <linux/irq.h>
  15 #include <linux/dmi.h>
  16 #include <linux/device.h>
  17 #include <linux/suspend.h>
  18 #include <linux/reboot.h>
  19
  20 #include <asm/io.h>
  21
  22 #include <acpi/acpi_bus.h>
  23 #include <acpi/acpi_drivers.h>
  24 #include "sleep.h"
  25
  26 u8 sleep_states[ACPI_S_STATE_COUNT];
  27
  28 static void acpi_sleep_tts_switch(u32 acpi_state)
  29 {
  30         union acpi_object in_arg = { ACPI_TYPE_INTEGER };
  31         struct acpi_object_list arg_list = { 1, &in_arg };
  32         acpi_status status = AE_OK;
  33
  34         in_arg.integer.value = acpi_state;
  35         status = acpi_evaluate_object(NULL, "\\_TTS", &arg_list, NULL);
  36         if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
  37                 /*
  38                  * OS can't evaluate the _TTS object correctly. Some warning
  39                  * message will be printed. But it won't break anything.
  40                  */
  41                 printk(KERN_NOTICE "Failure in evaluating _TTS object\n");
  42         }
  43 }
  44
  45 static int tts_notify_reboot(struct notifier_block *this,
  46                         unsigned long code, void *x)
  47 {
  48         acpi_sleep_tts_switch(ACPI_STATE_S5);
  49         return NOTIFY_DONE;
  50 }
  51
  52 static struct notifier_block tts_notifier = {
  53         .notifier_call  = tts_notify_reboot,
  54         .next           = NULL,
  55         .priority       = 0,
  56 };
  57
  58 static int acpi_sleep_prepare(u32 acpi_state)
  59 {
  60 #ifdef CONFIG_ACPI_SLEEP
  61         /* do we have a wakeup address for S2 and S3? */
  62         if (acpi_state == ACPI_STATE_S3) {
  63                 if (!acpi_wakeup_address) {
  64                         return -EFAULT;
  65                 }
  66                 acpi_set_firmware_waking_vector(
  67                                 (acpi_physical_address)acpi_wakeup_address);
  68
  69         }
  70         ACPI_FLUSH_CPU_CACHE();
  71         acpi_enable_wakeup_device_prep(acpi_state);
  72 #endif
  73         printk(KERN_INFO PREFIX "Preparing to enter system sleep state S%d\n",
  74                 acpi_state);
  75         acpi_enter_sleep_state_prep(acpi_state);
  76         return 0;
  77 }
  78
  79 #ifdef CONFIG_ACPI_SLEEP
  80 static u32 acpi_target_sleep_state = ACPI_STATE_S0;
  81 /*
  82  * ACPI 1.0 wants us to execute _PTS before suspending devices, so we allow the
  83  * user to request that behavior by using the 'acpi_old_suspend_ordering'
  84  * kernel command line option that causes the following variable to be set.
  85  */
  86 static bool old_suspend_ordering;
  87
  88 void __init acpi_old_suspend_ordering(void)
  89 {
  90         old_suspend_ordering = true;
  91 }
  92
  93 /**
  94  *      acpi_pm_disable_gpes - Disable the GPEs.
  95  */
  96 static int acpi_pm_disable_gpes(void)
  97 {
  98         acpi_hw_disable_all_gpes();
  99         return 0;
 100 }
 101
 102 /**
 103  *      __acpi_pm_prepare - Prepare the platform to enter the target state.
 104  *
 105  *      If necessary, set the firmware waking vector and do arch-specific
 106  *      nastiness to get the wakeup code to the waking vector.
 107  */
 108 static int __acpi_pm_prepare(void)
 109 {
 110         int error = acpi_sleep_prepare(acpi_target_sleep_state);
 111
 112         if (error)
 113                 acpi_target_sleep_state = ACPI_STATE_S0;
 114         return error;
 115 }
 116
 117 /**
 118  *      acpi_pm_prepare - Prepare the platform to enter the target sleep
 119  *              state and disable the GPEs.
 120  */
 121 static int acpi_pm_prepare(void)
 122 {
 123         int error = __acpi_pm_prepare();
 124
 125         if (!error)
 126                 acpi_hw_disable_all_gpes();
 127         return error;
 128 }
 129
 130 /**
 131  *      acpi_pm_finish - Instruct the platform to leave a sleep state.
 132  *
 133  *      This is called after we wake back up (or if entering the sleep state
 134  *      failed).
 135  */
 136 static void acpi_pm_finish(void)
 137 {
 138         u32 acpi_state = acpi_target_sleep_state;
 139
 140         if (acpi_state == ACPI_STATE_S0)
 141                 return;
 142
 143         printk(KERN_INFO PREFIX "Waking up from system sleep state S%d\n",
 144                 acpi_state);
 145         acpi_disable_wakeup_device(acpi_state);
 146         acpi_leave_sleep_state(acpi_state);
 147
 148         /* reset firmware waking vector */
 149         acpi_set_firmware_waking_vector((acpi_physical_address) 0);
 150
 151         acpi_target_sleep_state = ACPI_STATE_S0;
 152 }
 153
 154 /**
 155  *      acpi_pm_end - Finish up suspend sequence.
 156  */
 157 static void acpi_pm_end(void)
 158 {
 159         /*
 160          * This is necessary in case acpi_pm_finish() is not called during a
 161          * failing transition to a sleep state.
 162          */
 163         acpi_target_sleep_state = ACPI_STATE_S0;
 164         acpi_sleep_tts_switch(acpi_target_sleep_state);
 165 }
 166 #else /* !CONFIG_ACPI_SLEEP */
 167 #define acpi_target_sleep_state ACPI_STATE_S0
 168 #endif /* CONFIG_ACPI_SLEEP */
 169
 170 #ifdef CONFIG_SUSPEND
 171 extern void do_suspend_lowlevel(void);
 172
 173 static u32 acpi_suspend_states[] = {
 174         [PM_SUSPEND_ON] = ACPI_STATE_S0,
 175         [PM_SUSPEND_STANDBY] = ACPI_STATE_S1,
 176         [PM_SUSPEND_MEM] = ACPI_STATE_S3,
 177         [PM_SUSPEND_MAX] = ACPI_STATE_S5
 178 };
 179
 180 /**
 181  *      acpi_suspend_begin - Set the target system sleep state to the state
 182  *              associated with given @pm_state, if supported.
 183  */
 184 static int acpi_suspend_begin(suspend_state_t pm_state)
 185 {
 186         u32 acpi_state = acpi_suspend_states[pm_state];
 187         int error = 0;
 188
 189         if (sleep_states[acpi_state]) {
 190                 acpi_target_sleep_state = acpi_state;
 191                 acpi_sleep_tts_switch(acpi_target_sleep_state);
 192         } else {
 193                 printk(KERN_ERR "ACPI does not support this state: %d\n",
 194                         pm_state);
 195                 error = -ENOSYS;
 196         }
 197         return error;
 198 }
 199
 200 /**
 201  *      acpi_suspend_enter - Actually enter a sleep state.
 202  *      @pm_state: ignored
 203  *
 204  *      Flush caches and go to sleep. For STR we have to call arch-specific
 205  *      assembly, which in turn call acpi_enter_sleep_state().
 206  *      It's unfortunate, but it works. Please fix if you're feeling frisky.
 207  */
 208 static int acpi_suspend_enter(suspend_state_t pm_state)
 209 {
 210         acpi_status status = AE_OK;
 211         unsigned long flags = 0;
 212         u32 acpi_state = acpi_target_sleep_state;
 213
 214         ACPI_FLUSH_CPU_CACHE();
 215
 216         /* Do arch specific saving of state. */
 217         if (acpi_state == ACPI_STATE_S3) {
 218                 int error = acpi_save_state_mem();
 219
 220                 if (error)
 221                         return error;
 222         }
 223
 224         local_irq_save(flags);
 225         acpi_enable_wakeup_device(acpi_state);
 226         switch (acpi_state) {
 227         case ACPI_STATE_S1:
 228                 barrier();
 229                 status = acpi_enter_sleep_state(acpi_state);
 230                 break;
 231
 232         case ACPI_STATE_S3:
 233                 do_suspend_lowlevel();
 234                 break;
 235         }
 236
 237         /* If ACPI is not enabled by the BIOS, we need to enable it here. */
 238         acpi_enable();
 239         /* Reprogram control registers and execute _BFS */
 240         acpi_leave_sleep_state_prep(acpi_state);
 241
 242         /* ACPI 3.0 specs (P62) says that it's the responsibility
 243          * of the OSPM to clear the status bit [ implying that the
 244          * POWER_BUTTON event should not reach userspace ]
 245          */
 246         if (ACPI_SUCCESS(status) && (acpi_state == ACPI_STATE_S3))
 247                 acpi_clear_event(ACPI_EVENT_POWER_BUTTON);
 248
 249         /*
 250          * Disable and clear GPE status before interrupt is enabled. Some GPEs
 251          * (like wakeup GPE) haven't handler, this can avoid such GPE misfire.
 252          * acpi_leave_sleep_state will reenable specific GPEs later
 253          */
 254         acpi_hw_disable_all_gpes();
 255
 256         local_irq_restore(flags);
 257         printk(KERN_DEBUG "Back to C!\n");
 258
 259         /* restore processor state */
 260         if (acpi_state == ACPI_STATE_S3)
 261                 acpi_restore_state_mem();
 262
 263         return ACPI_SUCCESS(status) ? 0 : -EFAULT;
 264 }
 265
 266 static int acpi_suspend_state_valid(suspend_state_t pm_state)
 267 {
 268         u32 acpi_state;
 269
 270         switch (pm_state) {
 271         case PM_SUSPEND_ON:
 272         case PM_SUSPEND_STANDBY:
 273         case PM_SUSPEND_MEM:
 274                 acpi_state = acpi_suspend_states[pm_state];
 275
 276                 return sleep_states[acpi_state];
 277         default:
 278                 return 0;
 279         }
 280 }
 281
 282 static struct platform_suspend_ops acpi_suspend_ops = {
 283         .valid = acpi_suspend_state_valid,
 284         .begin = acpi_suspend_begin,
 285         .prepare = acpi_pm_prepare,
 286         .enter = acpi_suspend_enter,
 287         .finish = acpi_pm_finish,
 288         .end = acpi_pm_end,
 289 };
 290
 291 /**
 292  *      acpi_suspend_begin_old - Set the target system sleep state to the
 293  *              state associated with given @pm_state, if supported, and
 294  *              execute the _PTS control method.  This function is used if the
 295  *              pre-ACPI 2.0 suspend ordering has been requested.
 296  */
 297 static int acpi_suspend_begin_old(suspend_state_t pm_state)
 298 {
 299         int error = acpi_suspend_begin(pm_state);
 300
 301         if (!error)
 302                 error = __acpi_pm_prepare();
 303         return error;
 304 }
 305
 306 /*
 307  * The following callbacks are used if the pre-ACPI 2.0 suspend ordering has
 308  * been requested.
 309  */
 310 static struct platform_suspend_ops acpi_suspend_ops_old = {
 311         .valid = acpi_suspend_state_valid,
 312         .begin = acpi_suspend_begin_old,
 313         .prepare = acpi_pm_disable_gpes,
 314         .enter = acpi_suspend_enter,
 315         .finish = acpi_pm_finish,
 316         .end = acpi_pm_end,
 317         .recover = acpi_pm_finish,
 318 };
 319
 320 static int __init init_old_suspend_ordering(const struct dmi_system_id *d)
 321 {
 322         old_suspend_ordering = true;
 323         return 0;
 324 }
 325
 326 static struct dmi_system_id __initdata acpisleep_dmi_table[] = {
 327         {
 328         .callback = init_old_suspend_ordering,
 329         .ident = "Abit KN9 (nForce4 variant)",
 330         .matches = {
 331                 DMI_MATCH(DMI_BOARD_VENDOR, "http://www.abit.com.tw/"),
 332                 DMI_MATCH(DMI_BOARD_NAME, "KN9 Series(NF-CK804)"),
 333                 },
 334         },
 335         {
 336         .callback = init_old_suspend_ordering,
 337         .ident = "HP xw4600 Workstation",
 338         .matches = {
 339                 DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 340                 DMI_MATCH(DMI_PRODUCT_NAME, "HP xw4600 Workstation"),
 341                 },
 342         },
 343         {},
 344 };
 345 #endif /* CONFIG_SUSPEND */
 346
 347 #ifdef CONFIG_HIBERNATION
 348 static unsigned long s4_hardware_signature;
 349 static struct acpi_table_facs *facs;
 350 static bool nosigcheck;
 351
 352 void __init acpi_no_s4_hw_signature(void)
 353 {
 354         nosigcheck = true;
 355 }
 356
 357 static int acpi_hibernation_begin(void)
 358 {
 359         acpi_target_sleep_state = ACPI_STATE_S4;
 360         acpi_sleep_tts_switch(acpi_target_sleep_state);
 361         return 0;
 362 }
 363
 364 static int acpi_hibernation_enter(void)
 365 {
 366         acpi_status status = AE_OK;
 367         unsigned long flags = 0;
 368
 369         ACPI_FLUSH_CPU_CACHE();
 370
 371         local_irq_save(flags);
 372         acpi_enable_wakeup_device(ACPI_STATE_S4);
 373         /* This shouldn't return.  If it returns, we have a problem */
 374         status = acpi_enter_sleep_state(ACPI_STATE_S4);
 375         /* Reprogram control registers and execute _BFS */
 376         acpi_leave_sleep_state_prep(ACPI_STATE_S4);
 377         local_irq_restore(flags);
 378
 379         return ACPI_SUCCESS(status) ? 0 : -EFAULT;
 380 }
 381
 382 static void acpi_hibernation_leave(void)
 383 {
 384         /*
 385          * If ACPI is not enabled by the BIOS and the boot kernel, we need to
 386          * enable it here.
 387          */
 388         acpi_enable();
 389         /* Reprogram control registers and execute _BFS */
 390         acpi_leave_sleep_state_prep(ACPI_STATE_S4);
 391         /* Check the hardware signature */
 392         if (facs && s4_hardware_signature != facs->hardware_signature) {
 393                 printk(KERN_EMERG "ACPI: Hardware changed while hibernated, "
 394                         "cannot resume!\n");
 395                 panic("ACPI S4 hardware signature mismatch");
 396         }
 397 }
 398
 399 static void acpi_pm_enable_gpes(void)
 400 {
 401         acpi_hw_enable_all_runtime_gpes();
 402 }
 403
 404 static struct platform_hibernation_ops acpi_hibernation_ops = {
 405         .begin = acpi_hibernation_begin,
 406         .end = acpi_pm_end,
 407         .pre_snapshot = acpi_pm_prepare,
 408         .finish = acpi_pm_finish,
 409         .prepare = acpi_pm_prepare,
 410         .enter = acpi_hibernation_enter,
 411         .leave = acpi_hibernation_leave,
 412         .pre_restore = acpi_pm_disable_gpes,
 413         .restore_cleanup = acpi_pm_enable_gpes,
 414 };
 415
 416 /**
 417  *      acpi_hibernation_begin_old - Set the target system sleep state to
 418  *              ACPI_STATE_S4 and execute the _PTS control method.  This
 419  *              function is used if the pre-ACPI 2.0 suspend ordering has been
 420  *              requested.
 421  */
 422 static int acpi_hibernation_begin_old(void)
 423 {
 424         int error;
 425         /*
 426          * The _TTS object should always be evaluated before the _PTS object.
 427          * When the old_suspended_ordering is true, the _PTS object is
 428          * evaluated in the acpi_sleep_prepare.
 429          */
 430         acpi_sleep_tts_switch(ACPI_STATE_S4);
 431
 432         error = acpi_sleep_prepare(ACPI_STATE_S4);
 433
 434         if (!error)
 435                 acpi_target_sleep_state = ACPI_STATE_S4;
 436         return error;
 437 }
 438
 439 /*
 440  * The following callbacks are used if the pre-ACPI 2.0 suspend ordering has
 441  * been requested.
 442  */
 443 static struct platform_hibernation_ops acpi_hibernation_ops_old = {
 444         .begin = acpi_hibernation_begin_old,
 445         .end = acpi_pm_end,
 446         .pre_snapshot = acpi_pm_disable_gpes,
 447         .finish = acpi_pm_finish,
 448         .prepare = acpi_pm_disable_gpes,
 449         .enter = acpi_hibernation_enter,
 450         .leave = acpi_hibernation_leave,
 451         .pre_restore = acpi_pm_disable_gpes,
 452         .restore_cleanup = acpi_pm_enable_gpes,
 453         .recover = acpi_pm_finish,
 454 };
 455 #endif /* CONFIG_HIBERNATION */
 456
 457 int acpi_suspend(u32 acpi_state)
 458 {
 459         suspend_state_t states[] = {
 460                 [1] = PM_SUSPEND_STANDBY,
 461                 [3] = PM_SUSPEND_MEM,
 462                 [5] = PM_SUSPEND_MAX
 463         };
 464
 465         if (acpi_state < 6 && states[acpi_state])
 466                 return pm_suspend(states[acpi_state]);
 467         if (acpi_state == 4)
 468                 return hibernate();
 469         return -EINVAL;
 470 }
 471
 472 #ifdef CONFIG_PM_SLEEP
 473 /**
 474  *      acpi_pm_device_sleep_state - return preferred power state of ACPI device
 475  *              in the system sleep state given by %acpi_target_sleep_state
 476  *      @dev: device to examine; its driver model wakeup flags control
 477  *              whether it should be able to wake up the system
 478  *      @d_min_p: used to store the upper limit of allowed states range
 479  *      Return value: preferred power state of the device on success, -ENODEV on
 480  *              failure (ie. if there's no 'struct acpi_device' for @dev)
 481  *
 482  *      Find the lowest power (highest number) ACPI device power state that
 483  *      device @dev can be in while the system is in the sleep state represented
 484  *      by %acpi_target_sleep_state.  If @wake is nonzero, the device should be
 485  *      able to wake up the system from this sleep state.  If @d_min_p is set,
 486  *      the highest power (lowest number) device power state of @dev allowed
 487  *      in this system sleep state is stored at the location pointed to by it.
 488  *
 489  *      The caller must ensure that @dev is valid before using this function.
 490  *      The caller is also responsible for figuring out if the device is
 491  *      supposed to be able to wake up the system and passing this information
 492  *      via @wake.
 493  */
 494
 495 int acpi_pm_device_sleep_state(struct device *dev, int *d_min_p)
 496 {
 497         acpi_handle handle = DEVICE_ACPI_HANDLE(dev);
 498         struct acpi_device *adev;
 499         char acpi_method[] = "_SxD";
 500         unsigned long long d_min, d_max;
 501
 502         if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
 503                 printk(KERN_DEBUG "ACPI handle has no context!\n");
 504                 return -ENODEV;
 505         }
 506
 507         acpi_method[2] = '0' + acpi_target_sleep_state;
 508         /*
 509          * If the sleep state is S0, we will return D3, but if the device has
 510          * _S0W, we will use the value from _S0W
 511          */
 512         d_min = ACPI_STATE_D0;
 513         d_max = ACPI_STATE_D3;
 514
 515         /*
 516          * If present, _SxD methods return the minimum D-state (highest power
 517          * state) we can use for the corresponding S-states.  Otherwise, the
 518          * minimum D-state is D0 (ACPI 3.x).
 519          *
 520          * NOTE: We rely on acpi_evaluate_integer() not clobbering the integer
 521          * provided -- that's our fault recovery, we ignore retval.
 522          */
 523         if (acpi_target_sleep_state > ACPI_STATE_S0)
 524                 acpi_evaluate_integer(handle, acpi_method, NULL, &d_min);
 525
 526         /*
 527          * If _PRW says we can wake up the system from the target sleep state,
 528          * the D-state returned by _SxD is sufficient for that (we assume a
 529          * wakeup-aware driver if wake is set).  Still, if _SxW exists
 530          * (ACPI 3.x), it should return the maximum (lowest power) D-state that
 531          * can wake the system.  _S0W may be valid, too.
 532          */
 533         if (acpi_target_sleep_state == ACPI_STATE_S0 ||
 534             (device_may_wakeup(dev) && adev->wakeup.state.enabled &&
 535              adev->wakeup.sleep_state <= acpi_target_sleep_state)) {
 536                 acpi_status status;
 537
 538                 acpi_method[3] = 'W';
 539                 status = acpi_evaluate_integer(handle, acpi_method, NULL,
 540                                                 &d_max);
 541                 if (ACPI_FAILURE(status)) {
 542                         d_max = d_min;
 543                 } else if (d_max < d_min) {
 544                         /* Warn the user of the broken DSDT */
 545                         printk(KERN_WARNING "ACPI: Wrong value from %s\n",
 546                                 acpi_method);
 547                         /* Sanitize it */
 548                         d_min = d_max;
 549                 }
 550         }
 551
 552         if (d_min_p)
 553                 *d_min_p = d_min;
 554         return d_max;
 555 }
 556
 557 /**
 558  *      acpi_pm_device_sleep_wake - enable or disable the system wake-up
 559  *                                  capability of given device
 560  *      @dev: device to handle
 561  *      @enable: 'true' - enable, 'false' - disable the wake-up capability
 562  */
 563 int acpi_pm_device_sleep_wake(struct device *dev, bool enable)
 564 {
 565         acpi_handle handle;
 566         struct acpi_device *adev;
 567
 568         if (!device_may_wakeup(dev))
 569                 return -EINVAL;
 570
 571         handle = DEVICE_ACPI_HANDLE(dev);
 572         if (!handle || ACPI_FAILURE(acpi_bus_get_device(handle, &adev))) {
 573                 printk(KERN_DEBUG "ACPI handle has no context!\n");
 574                 return -ENODEV;
 575         }
 576
 577         return enable ?
 578                 acpi_enable_wakeup_device_power(adev, acpi_target_sleep_state) :
 579                 acpi_disable_wakeup_device_power(adev);
 580 }
 581 #endif
 582
 583 static void acpi_power_off_prepare(void)
 584 {
 585         /* Prepare to power off the system */
 586         acpi_sleep_prepare(ACPI_STATE_S5);
 587         acpi_hw_disable_all_gpes();
 588 }
 589
 590 static void acpi_power_off(void)
 591 {
 592         /* acpi_sleep_prepare(ACPI_STATE_S5) should have already been called */
 593         printk("%s called\n", __func__);
 594         local_irq_disable();
 595         acpi_enable_wakeup_device(ACPI_STATE_S5);
 596         acpi_enter_sleep_state(ACPI_STATE_S5);
 597 }
 598
 599 int __init acpi_sleep_init(void)
 600 {
 601         acpi_status status;
 602         u8 type_a, type_b;
 603 #ifdef CONFIG_SUSPEND
 604         int i = 0;
 605
 606         dmi_check_system(acpisleep_dmi_table);
 607 #endif
 608
 609         if (acpi_disabled)
 610                 return 0;
 611
 612         sleep_states[ACPI_STATE_S0] = 1;
 613         printk(KERN_INFO PREFIX "(supports S0");
 614
 615 #ifdef CONFIG_SUSPEND
 616         for (i = ACPI_STATE_S1; i < ACPI_STATE_S4; i++) {
 617                 status = acpi_get_sleep_type_data(i, &type_a, &type_b);
 618                 if (ACPI_SUCCESS(status)) {
 619                         sleep_states[i] = 1;
 620                         printk(" S%d", i);
 621                 }
 622         }
 623
 624         suspend_set_ops(old_suspend_ordering ?
 625                 &acpi_suspend_ops_old : &acpi_suspend_ops);
 626 #endif
 627
 628 #ifdef CONFIG_HIBERNATION
 629         status = acpi_get_sleep_type_data(ACPI_STATE_S4, &type_a, &type_b);
 630         if (ACPI_SUCCESS(status)) {
 631                 hibernation_set_ops(old_suspend_ordering ?
 632                         &acpi_hibernation_ops_old : &acpi_hibernation_ops);
 633                 sleep_states[ACPI_STATE_S4] = 1;
 634                 printk(" S4");
 635                 if (!nosigcheck) {
 636                         acpi_get_table_by_index(ACPI_TABLE_INDEX_FACS,
 637                                 (struct acpi_table_header **)&facs);
 638                         if (facs)
 639                                 s4_hardware_signature =
 640                                         facs->hardware_signature;
 641                 }
 642         }
 643 #endif
 644         status = acpi_get_sleep_type_data(ACPI_STATE_S5, &type_a, &type_b);
 645         if (ACPI_SUCCESS(status)) {
 646                 sleep_states[ACPI_STATE_S5] = 1;
 647                 printk(" S5");
 648                 pm_power_off_prepare = acpi_power_off_prepare;
 649                 pm_power_off = acpi_power_off;
 650         }
 651         printk(")\n");
 652         /*
 653          * Register the tts_notifier to reboot notifier list so that the _TTS
 654          * object can also be evaluated when the system enters S5.
 655          */
 656         register_reboot_notifier(&tts_notifier);
 657         return 0;
 658 }