drivers/acpi/processor_idle.c

   1 /*
   2  * processor_idle - idle state submodule to the ACPI processor driver
   3  *
   4  *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
   5  *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
   6  *  Copyright (C) 2004, 2005 Dominik Brodowski <linux@brodo.de>
   7  *  Copyright (C) 2004  Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
   8  *                      - Added processor hotplug support
   9  *  Copyright (C) 2005  Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
  10  *                      - Added support for C3 on SMP
  11  *
  12  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  13  *
  14  *  This program is free software; you can redistribute it and/or modify
  15  *  it under the terms of the GNU General Public License as published by
  16  *  the Free Software Foundation; either version 2 of the License, or (at
  17  *  your option) any later version.
  18  *
  19  *  This program is distributed in the hope that it will be useful, but
  20  *  WITHOUT ANY WARRANTY; without even the implied warranty of
  21  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22  *  General Public License for more details.
  23  *
  24  *  You should have received a copy of the GNU General Public License along
  25  *  with this program; if not, write to the Free Software Foundation, Inc.,
  26  *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  27  *
  28  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  29  */
  30
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/init.h>
  34 #include <linux/cpufreq.h>
  35 #include <linux/proc_fs.h>
  36 #include <linux/seq_file.h>
  37 #include <linux/acpi.h>
  38 #include <linux/dmi.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/sched.h>        /* need_resched() */
  41 #include <linux/latency.h>
  42
  43 /*
  44  * Include the apic definitions for x86 to have the APIC timer related defines
  45  * available also for UP (on SMP it gets magically included via linux/smp.h).
  46  * asm/acpi.h is not an option, as it would require more include magic. Also
  47  * creating an empty asm-ia64/apic.h would just trade pest vs. cholera.
  48  */
  49 #ifdef CONFIG_X86
  50 #include <asm/apic.h>
  51 #endif
  52
  53 #include <asm/io.h>
  54 #include <asm/uaccess.h>
  55
  56 #include <acpi/acpi_bus.h>
  57 #include <acpi/processor.h>
  58
  59 #define ACPI_PROCESSOR_COMPONENT        0x01000000
  60 #define ACPI_PROCESSOR_CLASS            "processor"
  61 #define ACPI_PROCESSOR_DRIVER_NAME      "ACPI Processor Driver"
  62 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  63 ACPI_MODULE_NAME("acpi_processor")
  64 #define ACPI_PROCESSOR_FILE_POWER       "power"
  65 #define US_TO_PM_TIMER_TICKS(t)         ((t * (PM_TIMER_FREQUENCY/1000)) / 1000)
  66 #define C2_OVERHEAD                     4       /* 1us (3.579 ticks per us) */
  67 #define C3_OVERHEAD                     4       /* 1us (3.579 ticks per us) */
  68 static void (*pm_idle_save) (void) __read_mostly;
  69 module_param(max_cstate, uint, 0644);
  70
  71 static unsigned int nocst __read_mostly;
  72 module_param(nocst, uint, 0000);
  73
  74 /*
  75  * bm_history -- bit-mask with a bit per jiffy of bus-master activity
  76  * 1000 HZ: 0xFFFFFFFF: 32 jiffies = 32ms
  77  * 800 HZ: 0xFFFFFFFF: 32 jiffies = 40ms
  78  * 100 HZ: 0x0000000F: 4 jiffies = 40ms
  79  * reduce history for more aggressive entry into C3
  80  */
  81 static unsigned int bm_history __read_mostly =
  82     (HZ >= 800 ? 0xFFFFFFFF : ((1U << (HZ / 25)) - 1));
  83 module_param(bm_history, uint, 0644);
  84 /* --------------------------------------------------------------------------
  85                                 Power Management
  86    -------------------------------------------------------------------------- */
  87
  88 /*
  89  * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
  90  * For now disable this. Probably a bug somewhere else.
  91  *
  92  * To skip this limit, boot/load with a large max_cstate limit.
  93  */
  94 static int set_max_cstate(struct dmi_system_id *id)
  95 {
  96         if (max_cstate > ACPI_PROCESSOR_MAX_POWER)
  97                 return 0;
  98
  99         printk(KERN_NOTICE PREFIX "%s detected - limiting to C%ld max_cstate."
 100                " Override with \"processor.max_cstate=%d\"\n", id->ident,
 101                (long)id->driver_data, ACPI_PROCESSOR_MAX_POWER + 1);
 102
 103         max_cstate = (long)id->driver_data;
 104
 105         return 0;
 106 }
 107
 108 /* Actually this shouldn't be __cpuinitdata, would be better to fix the
 109    callers to only run once -AK */
 110 static struct dmi_system_id __cpuinitdata processor_power_dmi_table[] = {
 111         { set_max_cstate, "IBM ThinkPad R40e", {
 112           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 113           DMI_MATCH(DMI_BIOS_VERSION,"1SET70WW")}, (void *)1},
 114         { set_max_cstate, "IBM ThinkPad R40e", {
 115           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 116           DMI_MATCH(DMI_BIOS_VERSION,"1SET60WW")}, (void *)1},
 117         { set_max_cstate, "IBM ThinkPad R40e", {
 118           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 119           DMI_MATCH(DMI_BIOS_VERSION,"1SET43WW") }, (void*)1},
 120         { set_max_cstate, "IBM ThinkPad R40e", {
 121           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 122           DMI_MATCH(DMI_BIOS_VERSION,"1SET45WW") }, (void*)1},
 123         { set_max_cstate, "IBM ThinkPad R40e", {
 124           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 125           DMI_MATCH(DMI_BIOS_VERSION,"1SET47WW") }, (void*)1},
 126         { set_max_cstate, "IBM ThinkPad R40e", {
 127           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 128           DMI_MATCH(DMI_BIOS_VERSION,"1SET50WW") }, (void*)1},
 129         { set_max_cstate, "IBM ThinkPad R40e", {
 130           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 131           DMI_MATCH(DMI_BIOS_VERSION,"1SET52WW") }, (void*)1},
 132         { set_max_cstate, "IBM ThinkPad R40e", {
 133           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 134           DMI_MATCH(DMI_BIOS_VERSION,"1SET55WW") }, (void*)1},
 135         { set_max_cstate, "IBM ThinkPad R40e", {
 136           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 137           DMI_MATCH(DMI_BIOS_VERSION,"1SET56WW") }, (void*)1},
 138         { set_max_cstate, "IBM ThinkPad R40e", {
 139           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 140           DMI_MATCH(DMI_BIOS_VERSION,"1SET59WW") }, (void*)1},
 141         { set_max_cstate, "IBM ThinkPad R40e", {
 142           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 143           DMI_MATCH(DMI_BIOS_VERSION,"1SET60WW") }, (void*)1},
 144         { set_max_cstate, "IBM ThinkPad R40e", {
 145           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 146           DMI_MATCH(DMI_BIOS_VERSION,"1SET61WW") }, (void*)1},
 147         { set_max_cstate, "IBM ThinkPad R40e", {
 148           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 149           DMI_MATCH(DMI_BIOS_VERSION,"1SET62WW") }, (void*)1},
 150         { set_max_cstate, "IBM ThinkPad R40e", {
 151           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 152           DMI_MATCH(DMI_BIOS_VERSION,"1SET64WW") }, (void*)1},
 153         { set_max_cstate, "IBM ThinkPad R40e", {
 154           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 155           DMI_MATCH(DMI_BIOS_VERSION,"1SET65WW") }, (void*)1},
 156         { set_max_cstate, "IBM ThinkPad R40e", {
 157           DMI_MATCH(DMI_BIOS_VENDOR,"IBM"),
 158           DMI_MATCH(DMI_BIOS_VERSION,"1SET68WW") }, (void*)1},
 159         { set_max_cstate, "Medion 41700", {
 160           DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
 161           DMI_MATCH(DMI_BIOS_VERSION,"R01-A1J")}, (void *)1},
 162         { set_max_cstate, "Clevo 5600D", {
 163           DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
 164           DMI_MATCH(DMI_BIOS_VERSION,"SHE845M0.86C.0013.D.0302131307")},
 165          (void *)2},
 166         {},
 167 };
 168
 169 static inline u32 ticks_elapsed(u32 t1, u32 t2)
 170 {
 171         if (t2 >= t1)
 172                 return (t2 - t1);
 173         else if (!(acpi_gbl_FADT.flags & ACPI_FADT_32BIT_TIMER))
 174                 return (((0x00FFFFFF - t1) + t2) & 0x00FFFFFF);
 175         else
 176                 return ((0xFFFFFFFF - t1) + t2);
 177 }
 178
 179 static void
 180 acpi_processor_power_activate(struct acpi_processor *pr,
 181                               struct acpi_processor_cx *new)
 182 {
 183         struct acpi_processor_cx *old;
 184
 185         if (!pr || !new)
 186                 return;
 187
 188         old = pr->power.state;
 189
 190         if (old)
 191                 old->promotion.count = 0;
 192         new->demotion.count = 0;
 193
 194         /* Cleanup from old state. */
 195         if (old) {
 196                 switch (old->type) {
 197                 case ACPI_STATE_C3:
 198                         /* Disable bus master reload */
 199                         if (new->type != ACPI_STATE_C3 && pr->flags.bm_check)
 200                                 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
 201                         break;
 202                 }
 203         }
 204
 205         /* Prepare to use new state. */
 206         switch (new->type) {
 207         case ACPI_STATE_C3:
 208                 /* Enable bus master reload */
 209                 if (old->type != ACPI_STATE_C3 && pr->flags.bm_check)
 210                         acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
 211                 break;
 212         }
 213
 214         pr->power.state = new;
 215
 216         return;
 217 }
 218
 219 static void acpi_safe_halt(void)
 220 {
 221         current_thread_info()->status &= ~TS_POLLING;
 222         /*
 223          * TS_POLLING-cleared state must be visible before we
 224          * test NEED_RESCHED:
 225          */
 226         smp_mb();
 227         if (!need_resched())
 228                 safe_halt();
 229         current_thread_info()->status |= TS_POLLING;
 230 }
 231
 232 static atomic_t c3_cpu_count;
 233
 234 /* Common C-state entry for C2, C3, .. */
 235 static void acpi_cstate_enter(struct acpi_processor_cx *cstate)
 236 {
 237         if (cstate->space_id == ACPI_CSTATE_FFH) {
 238                 /* Call into architectural FFH based C-state */
 239                 acpi_processor_ffh_cstate_enter(cstate);
 240         } else {
 241                 int unused;
 242                 /* IO port based C-state */
 243                 inb(cstate->address);
 244                 /* Dummy wait op - must do something useless after P_LVL2 read
 245                    because chipsets cannot guarantee that STPCLK# signal
 246                    gets asserted in time to freeze execution properly. */
 247                 unused = inl(acpi_gbl_FADT.xpm_timer_block.address);
 248         }
 249 }
 250
 251 #ifdef ARCH_APICTIMER_STOPS_ON_C3
 252
 253 /*
 254  * Some BIOS implementations switch to C3 in the published C2 state.
 255  * This seems to be a common problem on AMD boxen, but other vendors
 256  * are affected too. We pick the most conservative approach: we assume
 257  * that the local APIC stops in both C2 and C3.
 258  */
 259 static void acpi_timer_check_state(int state, struct acpi_processor *pr,
 260                                    struct acpi_processor_cx *cx)
 261 {
 262         struct acpi_processor_power *pwr = &pr->power;
 263
 264         /*
 265          * Check, if one of the previous states already marked the lapic
 266          * unstable
 267          */
 268         if (pwr->timer_broadcast_on_state < state)
 269                 return;
 270
 271         if (cx->type >= ACPI_STATE_C2)
 272                 pr->power.timer_broadcast_on_state = state;
 273 }
 274
 275 static void acpi_propagate_timer_broadcast(struct acpi_processor *pr)
 276 {
 277         cpumask_t mask = cpumask_of_cpu(pr->id);
 278
 279         if (pr->power.timer_broadcast_on_state < INT_MAX)
 280                 on_each_cpu(switch_APIC_timer_to_ipi, &mask, 1, 1);
 281         else
 282                 on_each_cpu(switch_ipi_to_APIC_timer, &mask, 1, 1);
 283 }
 284
 285 #else
 286
 287 static void acpi_timer_check_state(int state, struct acpi_processor *pr,
 288                                    struct acpi_processor_cx *cstate) { }
 289 static void acpi_propagate_timer_broadcast(struct acpi_processor *pr) { }
 290
 291 #endif
 292
 293 static void acpi_processor_idle(void)
 294 {
 295         struct acpi_processor *pr = NULL;
 296         struct acpi_processor_cx *cx = NULL;
 297         struct acpi_processor_cx *next_state = NULL;
 298         int sleep_ticks = 0;
 299         u32 t1, t2 = 0;
 300
 301         pr = processors[smp_processor_id()];
 302         if (!pr)
 303                 return;
 304
 305         /*
 306          * Interrupts must be disabled during bus mastering calculations and
 307          * for C2/C3 transitions.
 308          */
 309         local_irq_disable();
 310
 311         /*
 312          * Check whether we truly need to go idle, or should
 313          * reschedule:
 314          */
 315         if (unlikely(need_resched())) {
 316                 local_irq_enable();
 317                 return;
 318         }
 319
 320         cx = pr->power.state;
 321         if (!cx) {
 322                 if (pm_idle_save)
 323                         pm_idle_save();
 324                 else
 325                         acpi_safe_halt();
 326                 return;
 327         }
 328
 329         /*
 330          * Check BM Activity
 331          * -----------------
 332          * Check for bus mastering activity (if required), record, and check
 333          * for demotion.
 334          */
 335         if (pr->flags.bm_check) {
 336                 u32 bm_status = 0;
 337                 unsigned long diff = jiffies - pr->power.bm_check_timestamp;
 338
 339                 if (diff > 31)
 340                         diff = 31;
 341
 342                 pr->power.bm_activity <<= diff;
 343
 344                 acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
 345                 if (bm_status) {
 346                         pr->power.bm_activity |= 0x1;
 347                         acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
 348                 }
 349                 /*
 350                  * PIIX4 Erratum #18: Note that BM_STS doesn't always reflect
 351                  * the true state of bus mastering activity; forcing us to
 352                  * manually check the BMIDEA bit of each IDE channel.
 353                  */
 354                 else if (errata.piix4.bmisx) {
 355                         if ((inb_p(errata.piix4.bmisx + 0x02) & 0x01)
 356                             || (inb_p(errata.piix4.bmisx + 0x0A) & 0x01))
 357                                 pr->power.bm_activity |= 0x1;
 358                 }
 359
 360                 pr->power.bm_check_timestamp = jiffies;
 361
 362                 /*
 363                  * If bus mastering is or was active this jiffy, demote
 364                  * to avoid a faulty transition.  Note that the processor
 365                  * won't enter a low-power state during this call (to this
 366                  * function) but should upon the next.
 367                  *
 368                  * TBD: A better policy might be to fallback to the demotion
 369                  *      state (use it for this quantum only) istead of
 370                  *      demoting -- and rely on duration as our sole demotion
 371                  *      qualification.  This may, however, introduce DMA
 372                  *      issues (e.g. floppy DMA transfer overrun/underrun).
 373                  */
 374                 if ((pr->power.bm_activity & 0x1) &&
 375                     cx->demotion.threshold.bm) {
 376                         local_irq_enable();
 377                         next_state = cx->demotion.state;
 378                         goto end;
 379                 }
 380         }
 381
 382 #ifdef CONFIG_HOTPLUG_CPU
 383         /*
 384          * Check for P_LVL2_UP flag before entering C2 and above on
 385          * an SMP system. We do it here instead of doing it at _CST/P_LVL
 386          * detection phase, to work cleanly with logical CPU hotplug.
 387          */
 388         if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
 389             !pr->flags.has_cst && !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
 390                 cx = &pr->power.states[ACPI_STATE_C1];
 391 #endif
 392
 393         /*
 394          * Sleep:
 395          * ------
 396          * Invoke the current Cx state to put the processor to sleep.
 397          */
 398         if (cx->type == ACPI_STATE_C2 || cx->type == ACPI_STATE_C3) {
 399                 current_thread_info()->status &= ~TS_POLLING;
 400                 /*
 401                  * TS_POLLING-cleared state must be visible before we
 402                  * test NEED_RESCHED:
 403                  */
 404                 smp_mb();
 405                 if (need_resched()) {
 406                         current_thread_info()->status |= TS_POLLING;
 407                         local_irq_enable();
 408                         return;
 409                 }
 410         }
 411
 412         switch (cx->type) {
 413
 414         case ACPI_STATE_C1:
 415                 /*
 416                  * Invoke C1.
 417                  * Use the appropriate idle routine, the one that would
 418                  * be used without acpi C-states.
 419                  */
 420                 if (pm_idle_save)
 421                         pm_idle_save();
 422                 else
 423                         acpi_safe_halt();
 424
 425                 /*
 426                  * TBD: Can't get time duration while in C1, as resumes
 427                  *      go to an ISR rather than here.  Need to instrument
 428                  *      base interrupt handler.
 429                  */
 430                 sleep_ticks = 0xFFFFFFFF;
 431                 break;
 432
 433         case ACPI_STATE_C2:
 434                 /* Get start time (ticks) */
 435                 t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 436                 /* Invoke C2 */
 437                 acpi_cstate_enter(cx);
 438                 /* Get end time (ticks) */
 439                 t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 440
 441 #ifdef CONFIG_GENERIC_TIME
 442                 /* TSC halts in C2, so notify users */
 443                 mark_tsc_unstable();
 444 #endif
 445                 /* Re-enable interrupts */
 446                 local_irq_enable();
 447                 current_thread_info()->status |= TS_POLLING;
 448                 /* Compute time (ticks) that we were actually asleep */
 449                 sleep_ticks =
 450                     ticks_elapsed(t1, t2) - cx->latency_ticks - C2_OVERHEAD;
 451                 break;
 452
 453         case ACPI_STATE_C3:
 454
 455                 if (pr->flags.bm_check) {
 456                         if (atomic_inc_return(&c3_cpu_count) ==
 457                             num_online_cpus()) {
 458                                 /*
 459                                  * All CPUs are trying to go to C3
 460                                  * Disable bus master arbitration
 461                                  */
 462                                 acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1);
 463                         }
 464                 } else {
 465                         /* SMP with no shared cache... Invalidate cache  */
 466                         ACPI_FLUSH_CPU_CACHE();
 467                 }
 468
 469                 /* Get start time (ticks) */
 470                 t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 471                 /* Invoke C3 */
 472                 acpi_cstate_enter(cx);
 473                 /* Get end time (ticks) */
 474                 t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 475                 if (pr->flags.bm_check) {
 476                         /* Enable bus master arbitration */
 477                         atomic_dec(&c3_cpu_count);
 478                         acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
 479                 }
 480
 481 #ifdef CONFIG_GENERIC_TIME
 482                 /* TSC halts in C3, so notify users */
 483                 mark_tsc_unstable();
 484 #endif
 485                 /* Re-enable interrupts */
 486                 local_irq_enable();
 487                 current_thread_info()->status |= TS_POLLING;
 488                 /* Compute time (ticks) that we were actually asleep */
 489                 sleep_ticks =
 490                     ticks_elapsed(t1, t2) - cx->latency_ticks - C3_OVERHEAD;
 491                 break;
 492
 493         default:
 494                 local_irq_enable();
 495                 return;
 496         }
 497         cx->usage++;
 498         if ((cx->type != ACPI_STATE_C1) && (sleep_ticks > 0))
 499                 cx->time += sleep_ticks;
 500
 501         next_state = pr->power.state;
 502
 503 #ifdef CONFIG_HOTPLUG_CPU
 504         /* Don't do promotion/demotion */
 505         if ((cx->type == ACPI_STATE_C1) && (num_online_cpus() > 1) &&
 506             !pr->flags.has_cst && !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED)) {
 507                 next_state = cx;
 508                 goto end;
 509         }
 510 #endif
 511
 512         /*
 513          * Promotion?
 514          * ----------
 515          * Track the number of longs (time asleep is greater than threshold)
 516          * and promote when the count threshold is reached.  Note that bus
 517          * mastering activity may prevent promotions.
 518          * Do not promote above max_cstate.
 519          */
 520         if (cx->promotion.state &&
 521             ((cx->promotion.state - pr->power.states) <= max_cstate)) {
 522                 if (sleep_ticks > cx->promotion.threshold.ticks &&
 523                   cx->promotion.state->latency <= system_latency_constraint()) {
 524                         cx->promotion.count++;
 525                         cx->demotion.count = 0;
 526                         if (cx->promotion.count >=
 527                             cx->promotion.threshold.count) {
 528                                 if (pr->flags.bm_check) {
 529                                         if (!
 530                                             (pr->power.bm_activity & cx->
 531                                              promotion.threshold.bm)) {
 532                                                 next_state =
 533                                                     cx->promotion.state;
 534                                                 goto end;
 535                                         }
 536                                 } else {
 537                                         next_state = cx->promotion.state;
 538                                         goto end;
 539                                 }
 540                         }
 541                 }
 542         }
 543
 544         /*
 545          * Demotion?
 546          * ---------
 547          * Track the number of shorts (time asleep is less than time threshold)
 548          * and demote when the usage threshold is reached.
 549          */
 550         if (cx->demotion.state) {
 551                 if (sleep_ticks < cx->demotion.threshold.ticks) {
 552                         cx->demotion.count++;
 553                         cx->promotion.count = 0;
 554                         if (cx->demotion.count >= cx->demotion.threshold.count) {
 555                                 next_state = cx->demotion.state;
 556                                 goto end;
 557                         }
 558                 }
 559         }
 560
 561       end:
 562         /*
 563          * Demote if current state exceeds max_cstate
 564          * or if the latency of the current state is unacceptable
 565          */
 566         if ((pr->power.state - pr->power.states) > max_cstate ||
 567                 pr->power.state->latency > system_latency_constraint()) {
 568                 if (cx->demotion.state)
 569                         next_state = cx->demotion.state;
 570         }
 571
 572         /*
 573          * New Cx State?
 574          * -------------
 575          * If we're going to start using a new Cx state we must clean up
 576          * from the previous and prepare to use the new.
 577          */
 578         if (next_state != pr->power.state)
 579                 acpi_processor_power_activate(pr, next_state);
 580 }
 581
 582 static int acpi_processor_set_power_policy(struct acpi_processor *pr)
 583 {
 584         unsigned int i;
 585         unsigned int state_is_set = 0;
 586         struct acpi_processor_cx *lower = NULL;
 587         struct acpi_processor_cx *higher = NULL;
 588         struct acpi_processor_cx *cx;
 589
 590
 591         if (!pr)
 592                 return -EINVAL;
 593
 594         /*
 595          * This function sets the default Cx state policy (OS idle handler).
 596          * Our scheme is to promote quickly to C2 but more conservatively
 597          * to C3.  We're favoring C2  for its characteristics of low latency
 598          * (quick response), good power savings, and ability to allow bus
 599          * mastering activity.  Note that the Cx state policy is completely
 600          * customizable and can be altered dynamically.
 601          */
 602
 603         /* startup state */
 604         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
 605                 cx = &pr->power.states[i];
 606                 if (!cx->valid)
 607                         continue;
 608
 609                 if (!state_is_set)
 610                         pr->power.state = cx;
 611                 state_is_set++;
 612                 break;
 613         }
 614
 615         if (!state_is_set)
 616                 return -ENODEV;
 617
 618         /* demotion */
 619         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
 620                 cx = &pr->power.states[i];
 621                 if (!cx->valid)
 622                         continue;
 623
 624                 if (lower) {
 625                         cx->demotion.state = lower;
 626                         cx->demotion.threshold.ticks = cx->latency_ticks;
 627                         cx->demotion.threshold.count = 1;
 628                         if (cx->type == ACPI_STATE_C3)
 629                                 cx->demotion.threshold.bm = bm_history;
 630                 }
 631
 632                 lower = cx;
 633         }
 634
 635         /* promotion */
 636         for (i = (ACPI_PROCESSOR_MAX_POWER - 1); i > 0; i--) {
 637                 cx = &pr->power.states[i];
 638                 if (!cx->valid)
 639                         continue;
 640
 641                 if (higher) {
 642                         cx->promotion.state = higher;
 643                         cx->promotion.threshold.ticks = cx->latency_ticks;
 644                         if (cx->type >= ACPI_STATE_C2)
 645                                 cx->promotion.threshold.count = 4;
 646                         else
 647                                 cx->promotion.threshold.count = 10;
 648                         if (higher->type == ACPI_STATE_C3)
 649                                 cx->promotion.threshold.bm = bm_history;
 650                 }
 651
 652                 higher = cx;
 653         }
 654
 655         return 0;
 656 }
 657
 658 static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 659 {
 660
 661         if (!pr)
 662                 return -EINVAL;
 663
 664         if (!pr->pblk)
 665                 return -ENODEV;
 666
 667         /* if info is obtained from pblk/fadt, type equals state */
 668         pr->power.states[ACPI_STATE_C2].type = ACPI_STATE_C2;
 669         pr->power.states[ACPI_STATE_C3].type = ACPI_STATE_C3;
 670
 671 #ifndef CONFIG_HOTPLUG_CPU
 672         /*
 673          * Check for P_LVL2_UP flag before entering C2 and above on
 674          * an SMP system.
 675          */
 676         if ((num_online_cpus() > 1) &&
 677             !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
 678                 return -ENODEV;
 679 #endif
 680
 681         /* determine C2 and C3 address from pblk */
 682         pr->power.states[ACPI_STATE_C2].address = pr->pblk + 4;
 683         pr->power.states[ACPI_STATE_C3].address = pr->pblk + 5;
 684
 685         /* determine latencies from FADT */
 686         pr->power.states[ACPI_STATE_C2].latency = acpi_gbl_FADT.C2latency;
 687         pr->power.states[ACPI_STATE_C3].latency = acpi_gbl_FADT.C3latency;
 688
 689         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 690                           "lvl2[0x%08x] lvl3[0x%08x]\n",
 691                           pr->power.states[ACPI_STATE_C2].address,
 692                           pr->power.states[ACPI_STATE_C3].address));
 693
 694         return 0;
 695 }
 696
 697 static int acpi_processor_get_power_info_default(struct acpi_processor *pr)
 698 {
 699         if (!pr->power.states[ACPI_STATE_C1].valid) {
 700                 /* set the first C-State to C1 */
 701                 /* all processors need to support C1 */
 702                 pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
 703                 pr->power.states[ACPI_STATE_C1].valid = 1;
 704         }
 705         /* the C0 state only exists as a filler in our array */
 706         pr->power.states[ACPI_STATE_C0].valid = 1;
 707         return 0;
 708 }
 709
 710 static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
 711 {
 712         acpi_status status = 0;
 713         acpi_integer count;
 714         int current_count;
 715         int i;
 716         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 717         union acpi_object *cst;
 718
 719
 720         if (nocst)
 721                 return -ENODEV;
 722
 723         current_count = 0;
 724
 725         status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
 726         if (ACPI_FAILURE(status)) {
 727                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n"));
 728                 return -ENODEV;
 729         }
 730
 731         cst = buffer.pointer;
 732
 733         /* There must be at least 2 elements */
 734         if (!cst || (cst->type != ACPI_TYPE_PACKAGE) || cst->package.count < 2) {
 735                 printk(KERN_ERR PREFIX "not enough elements in _CST\n");
 736                 status = -EFAULT;
 737                 goto end;
 738         }
 739
 740         count = cst->package.elements[0].integer.value;
 741
 742         /* Validate number of power states. */
 743         if (count < 1 || count != cst->package.count - 1) {
 744                 printk(KERN_ERR PREFIX "count given by _CST is not valid\n");
 745                 status = -EFAULT;
 746                 goto end;
 747         }
 748
 749         /* Tell driver that at least _CST is supported. */
 750         pr->flags.has_cst = 1;
 751
 752         for (i = 1; i <= count; i++) {
 753                 union acpi_object *element;
 754                 union acpi_object *obj;
 755                 struct acpi_power_register *reg;
 756                 struct acpi_processor_cx cx;
 757
 758                 memset(&cx, 0, sizeof(cx));
 759
 760                 element = &(cst->package.elements[i]);
 761                 if (element->type != ACPI_TYPE_PACKAGE)
 762                         continue;
 763
 764                 if (element->package.count != 4)
 765                         continue;
 766
 767                 obj = &(element->package.elements[0]);
 768
 769                 if (obj->type != ACPI_TYPE_BUFFER)
 770                         continue;
 771
 772                 reg = (struct acpi_power_register *)obj->buffer.pointer;
 773
 774                 if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
 775                     (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
 776                         continue;
 777
 778                 /* There should be an easy way to extract an integer... */
 779                 obj = &(element->package.elements[1]);
 780                 if (obj->type != ACPI_TYPE_INTEGER)
 781                         continue;
 782
 783                 cx.type = obj->integer.value;
 784                 /*
 785                  * Some buggy BIOSes won't list C1 in _CST -
 786                  * Let acpi_processor_get_power_info_default() handle them later
 787                  */
 788                 if (i == 1 && cx.type != ACPI_STATE_C1)
 789                         current_count++;
 790
 791                 cx.address = reg->address;
 792                 cx.index = current_count + 1;
 793
 794                 cx.space_id = ACPI_CSTATE_SYSTEMIO;
 795                 if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
 796                         if (acpi_processor_ffh_cstate_probe
 797                                         (pr->id, &cx, reg) == 0) {
 798                                 cx.space_id = ACPI_CSTATE_FFH;
 799                         } else if (cx.type != ACPI_STATE_C1) {
 800                                 /*
 801                                  * C1 is a special case where FIXED_HARDWARE
 802                                  * can be handled in non-MWAIT way as well.
 803                                  * In that case, save this _CST entry info.
 804                                  * That is, we retain space_id of SYSTEM_IO for
 805                                  * halt based C1.
 806                                  * Otherwise, ignore this info and continue.
 807                                  */
 808                                 continue;
 809                         }
 810                 }
 811
 812                 obj = &(element->package.elements[2]);
 813                 if (obj->type != ACPI_TYPE_INTEGER)
 814                         continue;
 815
 816                 cx.latency = obj->integer.value;
 817
 818                 obj = &(element->package.elements[3]);
 819                 if (obj->type != ACPI_TYPE_INTEGER)
 820                         continue;
 821
 822                 cx.power = obj->integer.value;
 823
 824                 current_count++;
 825                 memcpy(&(pr->power.states[current_count]), &cx, sizeof(cx));
 826
 827                 /*
 828                  * We support total ACPI_PROCESSOR_MAX_POWER - 1
 829                  * (From 1 through ACPI_PROCESSOR_MAX_POWER - 1)
 830                  */
 831                 if (current_count >= (ACPI_PROCESSOR_MAX_POWER - 1)) {
 832                         printk(KERN_WARNING
 833                                "Limiting number of power states to max (%d)\n",
 834                                ACPI_PROCESSOR_MAX_POWER);
 835                         printk(KERN_WARNING
 836                                "Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n");
 837                         break;
 838                 }
 839         }
 840
 841         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
 842                           current_count));
 843
 844         /* Validate number of power states discovered */
 845         if (current_count < 2)
 846                 status = -EFAULT;
 847
 848       end:
 849         kfree(buffer.pointer);
 850
 851         return status;
 852 }
 853
 854 static void acpi_processor_power_verify_c2(struct acpi_processor_cx *cx)
 855 {
 856
 857         if (!cx->address)
 858                 return;
 859
 860         /*
 861          * C2 latency must be less than or equal to 100
 862          * microseconds.
 863          */
 864         else if (cx->latency > ACPI_PROCESSOR_MAX_C2_LATENCY) {
 865                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 866                                   "latency too large [%d]\n", cx->latency));
 867                 return;
 868         }
 869
 870         /*
 871          * Otherwise we've met all of our C2 requirements.
 872          * Normalize the C2 latency to expidite policy
 873          */
 874         cx->valid = 1;
 875         cx->latency_ticks = US_TO_PM_TIMER_TICKS(cx->latency);
 876
 877         return;
 878 }
 879
 880 static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
 881                                            struct acpi_processor_cx *cx)
 882 {
 883         static int bm_check_flag;
 884
 885
 886         if (!cx->address)
 887                 return;
 888
 889         /*
 890          * C3 latency must be less than or equal to 1000
 891          * microseconds.
 892          */
 893         else if (cx->latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
 894                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 895                                   "latency too large [%d]\n", cx->latency));
 896                 return;
 897         }
 898
 899         /*
 900          * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
 901          * DMA transfers are used by any ISA device to avoid livelock.
 902          * Note that we could disable Type-F DMA (as recommended by
 903          * the erratum), but this is known to disrupt certain ISA
 904          * devices thus we take the conservative approach.
 905          */
 906         else if (errata.piix4.fdma) {
 907                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 908                                   "C3 not supported on PIIX4 with Type-F DMA\n"));
 909                 return;
 910         }
 911
 912         /* All the logic here assumes flags.bm_check is same across all CPUs */
 913         if (!bm_check_flag) {
 914                 /* Determine whether bm_check is needed based on CPU  */
 915                 acpi_processor_power_init_bm_check(&(pr->flags), pr->id);
 916                 bm_check_flag = pr->flags.bm_check;
 917         } else {
 918                 pr->flags.bm_check = bm_check_flag;
 919         }
 920
 921         if (pr->flags.bm_check) {
 922                 /* bus mastering control is necessary */
 923                 if (!pr->flags.bm_control) {
 924                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 925                                           "C3 support requires bus mastering control\n"));
 926                         return;
 927                 }
 928         } else {
 929                 /*
 930                  * WBINVD should be set in fadt, for C3 state to be
 931                  * supported on when bm_check is not required.
 932                  */
 933                 if (!(acpi_gbl_FADT.flags & ACPI_FADT_WBINVD)) {
 934                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 935                                           "Cache invalidation should work properly"
 936                                           " for C3 to be enabled on SMP systems\n"));
 937                         return;
 938                 }
 939                 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
 940         }
 941
 942         /*
 943          * Otherwise we've met all of our C3 requirements.
 944          * Normalize the C3 latency to expidite policy.  Enable
 945          * checking of bus mastering status (bm_check) so we can
 946          * use this in our C3 policy
 947          */
 948         cx->valid = 1;
 949         cx->latency_ticks = US_TO_PM_TIMER_TICKS(cx->latency);
 950
 951         return;
 952 }
 953
 954 static int acpi_processor_power_verify(struct acpi_processor *pr)
 955 {
 956         unsigned int i;
 957         unsigned int working = 0;
 958
 959         pr->power.timer_broadcast_on_state = INT_MAX;
 960
 961         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
 962                 struct acpi_processor_cx *cx = &pr->power.states[i];
 963
 964                 switch (cx->type) {
 965                 case ACPI_STATE_C1:
 966                         cx->valid = 1;
 967                         break;
 968
 969                 case ACPI_STATE_C2:
 970                         acpi_processor_power_verify_c2(cx);
 971                         if (cx->valid)
 972                                 acpi_timer_check_state(i, pr, cx);
 973                         break;
 974
 975                 case ACPI_STATE_C3:
 976                         acpi_processor_power_verify_c3(pr, cx);
 977                         if (cx->valid)
 978                                 acpi_timer_check_state(i, pr, cx);
 979                         break;
 980                 }
 981
 982                 if (cx->valid)
 983                         working++;
 984         }
 985
 986         acpi_propagate_timer_broadcast(pr);
 987
 988         return (working);
 989 }
 990
 991 static int acpi_processor_get_power_info(struct acpi_processor *pr)
 992 {
 993         unsigned int i;
 994         int result;
 995
 996
 997         /* NOTE: the idle thread may not be running while calling
 998          * this function */
 999
1000         /* Zero initialize all the C-states info. */
1001         memset(pr->power.states, 0, sizeof(pr->power.states));
1002
1003         result = acpi_processor_get_power_info_cst(pr);
1004         if (result == -ENODEV)
1005                 result = acpi_processor_get_power_info_fadt(pr);
1006
1007         if (result)
1008                 return result;
1009
1010         acpi_processor_get_power_info_default(pr);
1011
1012         pr->power.count = acpi_processor_power_verify(pr);
1013
1014         /*
1015          * Set Default Policy
1016          * ------------------
1017          * Now that we know which states are supported, set the default
1018          * policy.  Note that this policy can be changed dynamically
1019          * (e.g. encourage deeper sleeps to conserve battery life when
1020          * not on AC).
1021          */
1022         result = acpi_processor_set_power_policy(pr);
1023         if (result)
1024                 return result;
1025
1026         /*
1027          * if one state of type C2 or C3 is available, mark this
1028          * CPU as being "idle manageable"
1029          */
1030         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
1031                 if (pr->power.states[i].valid) {
1032                         pr->power.count = i;
1033                         if (pr->power.states[i].type >= ACPI_STATE_C2)
1034                                 pr->flags.power = 1;
1035                 }
1036         }
1037
1038         return 0;
1039 }
1040
1041 int acpi_processor_cst_has_changed(struct acpi_processor *pr)
1042 {
1043         int result = 0;
1044
1045
1046         if (!pr)
1047                 return -EINVAL;
1048
1049         if (nocst) {
1050                 return -ENODEV;
1051         }
1052
1053         if (!pr->flags.power_setup_done)
1054                 return -ENODEV;
1055
1056         /* Fall back to the default idle loop */
1057         pm_idle = pm_idle_save;
1058         synchronize_sched();    /* Relies on interrupts forcing exit from idle. */
1059
1060         pr->flags.power = 0;
1061         result = acpi_processor_get_power_info(pr);
1062         if ((pr->flags.power == 1) && (pr->flags.power_setup_done))
1063                 pm_idle = acpi_processor_idle;
1064
1065         return result;
1066 }
1067
1068 /* proc interface */
1069
1070 static int acpi_processor_power_seq_show(struct seq_file *seq, void *offset)
1071 {
1072         struct acpi_processor *pr = seq->private;
1073         unsigned int i;
1074
1075
1076         if (!pr)
1077                 goto end;
1078
1079         seq_printf(seq, "active state:            C%zd\n"
1080                    "max_cstate:              C%d\n"
1081                    "bus master activity:     %08x\n"
1082                    "maximum allowed latency: %d usec\n",
1083                    pr->power.state ? pr->power.state - pr->power.states : 0,
1084                    max_cstate, (unsigned)pr->power.bm_activity,
1085                    system_latency_constraint());
1086
1087         seq_puts(seq, "states:\n");
1088
1089         for (i = 1; i <= pr->power.count; i++) {
1090                 seq_printf(seq, "   %cC%d:                  ",
1091                            (&pr->power.states[i] ==
1092                             pr->power.state ? '*' : ' '), i);
1093
1094                 if (!pr->power.states[i].valid) {
1095                         seq_puts(seq, "<not supported>\n");
1096                         continue;
1097                 }
1098
1099                 switch (pr->power.states[i].type) {
1100                 case ACPI_STATE_C1:
1101                         seq_printf(seq, "type[C1] ");
1102                         break;
1103                 case ACPI_STATE_C2:
1104                         seq_printf(seq, "type[C2] ");
1105                         break;
1106                 case ACPI_STATE_C3:
1107                         seq_printf(seq, "type[C3] ");
1108                         break;
1109                 default:
1110                         seq_printf(seq, "type[--] ");
1111                         break;
1112                 }
1113
1114                 if (pr->power.states[i].promotion.state)
1115                         seq_printf(seq, "promotion[C%zd] ",
1116                                    (pr->power.states[i].promotion.state -
1117                                     pr->power.states));
1118                 else
1119                         seq_puts(seq, "promotion[--] ");
1120
1121                 if (pr->power.states[i].demotion.state)
1122                         seq_printf(seq, "demotion[C%zd] ",
1123                                    (pr->power.states[i].demotion.state -
1124                                     pr->power.states));
1125                 else
1126                         seq_puts(seq, "demotion[--] ");
1127
1128                 seq_printf(seq, "latency[%03d] usage[%08d] duration[%020llu]\n",
1129                            pr->power.states[i].latency,
1130                            pr->power.states[i].usage,
1131                            (unsigned long long)pr->power.states[i].time);
1132         }
1133
1134       end:
1135         return 0;
1136 }
1137
1138 static int acpi_processor_power_open_fs(struct inode *inode, struct file *file)
1139 {
1140         return single_open(file, acpi_processor_power_seq_show,
1141                            PDE(inode)->data);
1142 }
1143
1144 static const struct file_operations acpi_processor_power_fops = {
1145         .open = acpi_processor_power_open_fs,
1146         .read = seq_read,
1147         .llseek = seq_lseek,
1148         .release = single_release,
1149 };
1150
1151 #ifdef CONFIG_SMP
1152 static void smp_callback(void *v)
1153 {
1154         /* we already woke the CPU up, nothing more to do */
1155 }
1156
1157 /*
1158  * This function gets called when a part of the kernel has a new latency
1159  * requirement.  This means we need to get all processors out of their C-state,
1160  * and then recalculate a new suitable C-state. Just do a cross-cpu IPI; that
1161  * wakes them all right up.
1162  */
1163 static int acpi_processor_latency_notify(struct notifier_block *b,
1164                 unsigned long l, void *v)
1165 {
1166         smp_call_function(smp_callback, NULL, 0, 1);
1167         return NOTIFY_OK;
1168 }
1169
1170 static struct notifier_block acpi_processor_latency_notifier = {
1171         .notifier_call = acpi_processor_latency_notify,
1172 };
1173 #endif
1174
1175 int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
1176                               struct acpi_device *device)
1177 {
1178         acpi_status status = 0;
1179         static int first_run;
1180         struct proc_dir_entry *entry = NULL;
1181         unsigned int i;
1182
1183
1184         if (!first_run) {
1185                 dmi_check_system(processor_power_dmi_table);
1186                 if (max_cstate < ACPI_C_STATES_MAX)
1187                         printk(KERN_NOTICE
1188                                "ACPI: processor limited to max C-state %d\n",
1189                                max_cstate);
1190                 first_run++;
1191 #ifdef CONFIG_SMP
1192                 register_latency_notifier(&acpi_processor_latency_notifier);
1193 #endif
1194         }
1195
1196         if (!pr)
1197                 return -EINVAL;
1198
1199         if (acpi_gbl_FADT.cst_control && !nocst) {
1200                 status =
1201                     acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
1202                 if (ACPI_FAILURE(status)) {
1203                         ACPI_EXCEPTION((AE_INFO, status,
1204                                         "Notifying BIOS of _CST ability failed"));
1205                 }
1206         }
1207
1208         acpi_processor_get_power_info(pr);
1209
1210         /*
1211          * Install the idle handler if processor power management is supported.
1212          * Note that we use previously set idle handler will be used on
1213          * platforms that only support C1.
1214          */
1215         if ((pr->flags.power) && (!boot_option_idle_override)) {
1216                 printk(KERN_INFO PREFIX "CPU%d (power states:", pr->id);
1217                 for (i = 1; i <= pr->power.count; i++)
1218                         if (pr->power.states[i].valid)
1219                                 printk(" C%d[C%d]", i,
1220                                        pr->power.states[i].type);
1221                 printk(")\n");
1222
1223                 if (pr->id == 0) {
1224                         pm_idle_save = pm_idle;
1225                         pm_idle = acpi_processor_idle;
1226                 }
1227         }
1228
1229         /* 'power' [R] */
1230         entry = create_proc_entry(ACPI_PROCESSOR_FILE_POWER,
1231                                   S_IRUGO, acpi_device_dir(device));
1232         if (!entry)
1233                 return -EIO;
1234         else {
1235                 entry->proc_fops = &acpi_processor_power_fops;
1236                 entry->data = acpi_driver_data(device);
1237                 entry->owner = THIS_MODULE;
1238         }
1239
1240         pr->flags.power_setup_done = 1;
1241
1242         return 0;
1243 }
1244
1245 int acpi_processor_power_exit(struct acpi_processor *pr,
1246                               struct acpi_device *device)
1247 {
1248
1249         pr->flags.power_setup_done = 0;
1250
1251         if (acpi_device_dir(device))
1252                 remove_proc_entry(ACPI_PROCESSOR_FILE_POWER,
1253                                   acpi_device_dir(device));
1254
1255         /* Unregister the idle handler when processor #0 is removed. */
1256         if (pr->id == 0) {
1257                 pm_idle = pm_idle_save;
1258
1259                 /*
1260                  * We are about to unload the current idle thread pm callback
1261                  * (pm_idle), Wait for all processors to update cached/local
1262                  * copies of pm_idle before proceeding.
1263                  */
1264                 cpu_idle_wait();
1265 #ifdef CONFIG_SMP
1266                 unregister_latency_notifier(&acpi_processor_latency_notifier);
1267 #endif
1268         }
1269
1270         return 0;
1271 }