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/slab.h>
  36 #include <linux/acpi.h>
  37 #include <linux/dmi.h>
  38 #include <linux/moduleparam.h>
  39 #include <linux/sched.h>        /* need_resched() */
  40 #include <linux/pm_qos.h>
  41 #include <linux/clockchips.h>
  42 #include <linux/cpuidle.h>
  43 #include <linux/irqflags.h>
  44
  45 /*
  46  * Include the apic definitions for x86 to have the APIC timer related defines
  47  * available also for UP (on SMP it gets magically included via linux/smp.h).
  48  * asm/acpi.h is not an option, as it would require more include magic. Also
  49  * creating an empty asm-ia64/apic.h would just trade pest vs. cholera.
  50  */
  51 #ifdef CONFIG_X86
  52 #include <asm/apic.h>
  53 #endif
  54
  55 #include <asm/io.h>
  56 #include <asm/uaccess.h>
  57
  58 #include <acpi/acpi_bus.h>
  59 #include <acpi/processor.h>
  60 #include <asm/processor.h>
  61
  62 #define PREFIX "ACPI: "
  63
  64 #define ACPI_PROCESSOR_CLASS            "processor"
  65 #define _COMPONENT              ACPI_PROCESSOR_COMPONENT
  66 ACPI_MODULE_NAME("processor_idle");
  67 #define PM_TIMER_TICK_NS                (1000000000ULL/PM_TIMER_FREQUENCY)
  68 #define C2_OVERHEAD                     1       /* 1us */
  69 #define C3_OVERHEAD                     1       /* 1us */
  70 #define PM_TIMER_TICKS_TO_US(p)         (((p) * 1000)/(PM_TIMER_FREQUENCY/1000))
  71
  72 static unsigned int max_cstate __read_mostly = ACPI_PROCESSOR_MAX_POWER;
  73 module_param(max_cstate, uint, 0000);
  74 static unsigned int nocst __read_mostly;
  75 module_param(nocst, uint, 0000);
  76 static int bm_check_disable __read_mostly;
  77 module_param(bm_check_disable, uint, 0000);
  78
  79 static unsigned int latency_factor __read_mostly = 2;
  80 module_param(latency_factor, uint, 0644);
  81
  82 static int disabled_by_idle_boot_param(void)
  83 {
  84         return boot_option_idle_override == IDLE_POLL ||
  85                 boot_option_idle_override == IDLE_FORCE_MWAIT ||
  86                 boot_option_idle_override == IDLE_HALT;
  87 }
  88
  89 /*
  90  * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
  91  * For now disable this. Probably a bug somewhere else.
  92  *
  93  * To skip this limit, boot/load with a large max_cstate limit.
  94  */
  95 static int set_max_cstate(const struct dmi_system_id *id)
  96 {
  97         if (max_cstate > ACPI_PROCESSOR_MAX_POWER)
  98                 return 0;
  99
 100         printk(KERN_NOTICE PREFIX "%s detected - limiting to C%ld max_cstate."
 101                " Override with \"processor.max_cstate=%d\"\n", id->ident,
 102                (long)id->driver_data, ACPI_PROCESSOR_MAX_POWER + 1);
 103
 104         max_cstate = (long)id->driver_data;
 105
 106         return 0;
 107 }
 108
 109 /* Actually this shouldn't be __cpuinitdata, would be better to fix the
 110    callers to only run once -AK */
 111 static struct dmi_system_id __cpuinitdata processor_power_dmi_table[] = {
 112         { set_max_cstate, "Clevo 5600D", {
 113           DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
 114           DMI_MATCH(DMI_BIOS_VERSION,"SHE845M0.86C.0013.D.0302131307")},
 115          (void *)2},
 116         { set_max_cstate, "Pavilion zv5000", {
 117           DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
 118           DMI_MATCH(DMI_PRODUCT_NAME,"Pavilion zv5000 (DS502A#ABA)")},
 119          (void *)1},
 120         { set_max_cstate, "Asus L8400B", {
 121           DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
 122           DMI_MATCH(DMI_PRODUCT_NAME,"L8400B series Notebook PC")},
 123          (void *)1},
 124         {},
 125 };
 126
 127
 128 /*
 129  * Callers should disable interrupts before the call and enable
 130  * interrupts after return.
 131  */
 132 static void acpi_safe_halt(void)
 133 {
 134         current_thread_info()->status &= ~TS_POLLING;
 135         /*
 136          * TS_POLLING-cleared state must be visible before we
 137          * test NEED_RESCHED:
 138          */
 139         smp_mb();
 140         if (!need_resched()) {
 141                 safe_halt();
 142                 local_irq_disable();
 143         }
 144         current_thread_info()->status |= TS_POLLING;
 145 }
 146
 147 #ifdef ARCH_APICTIMER_STOPS_ON_C3
 148
 149 /*
 150  * Some BIOS implementations switch to C3 in the published C2 state.
 151  * This seems to be a common problem on AMD boxen, but other vendors
 152  * are affected too. We pick the most conservative approach: we assume
 153  * that the local APIC stops in both C2 and C3.
 154  */
 155 static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 156                                    struct acpi_processor_cx *cx)
 157 {
 158         struct acpi_processor_power *pwr = &pr->power;
 159         u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2;
 160
 161         if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
 162                 return;
 163
 164         if (amd_e400_c1e_detected)
 165                 type = ACPI_STATE_C1;
 166
 167         /*
 168          * Check, if one of the previous states already marked the lapic
 169          * unstable
 170          */
 171         if (pwr->timer_broadcast_on_state < state)
 172                 return;
 173
 174         if (cx->type >= type)
 175                 pr->power.timer_broadcast_on_state = state;
 176 }
 177
 178 static void __lapic_timer_propagate_broadcast(void *arg)
 179 {
 180         struct acpi_processor *pr = (struct acpi_processor *) arg;
 181         unsigned long reason;
 182
 183         reason = pr->power.timer_broadcast_on_state < INT_MAX ?
 184                 CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
 185
 186         clockevents_notify(reason, &pr->id);
 187 }
 188
 189 static void lapic_timer_propagate_broadcast(struct acpi_processor *pr)
 190 {
 191         smp_call_function_single(pr->id, __lapic_timer_propagate_broadcast,
 192                                  (void *)pr, 1);
 193 }
 194
 195 /* Power(C) State timer broadcast control */
 196 static void lapic_timer_state_broadcast(struct acpi_processor *pr,
 197                                        struct acpi_processor_cx *cx,
 198                                        int broadcast)
 199 {
 200         int state = cx - pr->power.states;
 201
 202         if (state >= pr->power.timer_broadcast_on_state) {
 203                 unsigned long reason;
 204
 205                 reason = broadcast ?  CLOCK_EVT_NOTIFY_BROADCAST_ENTER :
 206                         CLOCK_EVT_NOTIFY_BROADCAST_EXIT;
 207                 clockevents_notify(reason, &pr->id);
 208         }
 209 }
 210
 211 #else
 212
 213 static void lapic_timer_check_state(int state, struct acpi_processor *pr,
 214                                    struct acpi_processor_cx *cstate) { }
 215 static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }
 216 static void lapic_timer_state_broadcast(struct acpi_processor *pr,
 217                                        struct acpi_processor_cx *cx,
 218                                        int broadcast)
 219 {
 220 }
 221
 222 #endif
 223
 224 /*
 225  * Suspend / resume control
 226  */
 227 static int acpi_idle_suspend;
 228 static u32 saved_bm_rld;
 229
 230 static void acpi_idle_bm_rld_save(void)
 231 {
 232         acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &saved_bm_rld);
 233 }
 234 static void acpi_idle_bm_rld_restore(void)
 235 {
 236         u32 resumed_bm_rld;
 237
 238         acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &resumed_bm_rld);
 239
 240         if (resumed_bm_rld != saved_bm_rld)
 241                 acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, saved_bm_rld);
 242 }
 243
 244 int acpi_processor_suspend(struct acpi_device * device, pm_message_t state)
 245 {
 246         if (acpi_idle_suspend == 1)
 247                 return 0;
 248
 249         acpi_idle_bm_rld_save();
 250         acpi_idle_suspend = 1;
 251         return 0;
 252 }
 253
 254 int acpi_processor_resume(struct acpi_device * device)
 255 {
 256         if (acpi_idle_suspend == 0)
 257                 return 0;
 258
 259         acpi_idle_bm_rld_restore();
 260         acpi_idle_suspend = 0;
 261         return 0;
 262 }
 263
 264 #if defined(CONFIG_X86)
 265 static void tsc_check_state(int state)
 266 {
 267         switch (boot_cpu_data.x86_vendor) {
 268         case X86_VENDOR_AMD:
 269         case X86_VENDOR_INTEL:
 270                 /*
 271                  * AMD Fam10h TSC will tick in all
 272                  * C/P/S0/S1 states when this bit is set.
 273                  */
 274                 if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 275                         return;
 276
 277                 /*FALL THROUGH*/
 278         default:
 279                 /* TSC could halt in idle, so notify users */
 280                 if (state > ACPI_STATE_C1)
 281                         mark_tsc_unstable("TSC halts in idle");
 282         }
 283 }
 284 #else
 285 static void tsc_check_state(int state) { return; }
 286 #endif
 287
 288 static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
 289 {
 290
 291         if (!pr)
 292                 return -EINVAL;
 293
 294         if (!pr->pblk)
 295                 return -ENODEV;
 296
 297         /* if info is obtained from pblk/fadt, type equals state */
 298         pr->power.states[ACPI_STATE_C2].type = ACPI_STATE_C2;
 299         pr->power.states[ACPI_STATE_C3].type = ACPI_STATE_C3;
 300
 301 #ifndef CONFIG_HOTPLUG_CPU
 302         /*
 303          * Check for P_LVL2_UP flag before entering C2 and above on
 304          * an SMP system.
 305          */
 306         if ((num_online_cpus() > 1) &&
 307             !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
 308                 return -ENODEV;
 309 #endif
 310
 311         /* determine C2 and C3 address from pblk */
 312         pr->power.states[ACPI_STATE_C2].address = pr->pblk + 4;
 313         pr->power.states[ACPI_STATE_C3].address = pr->pblk + 5;
 314
 315         /* determine latencies from FADT */
 316         pr->power.states[ACPI_STATE_C2].latency = acpi_gbl_FADT.c2_latency;
 317         pr->power.states[ACPI_STATE_C3].latency = acpi_gbl_FADT.c3_latency;
 318
 319         /*
 320          * FADT specified C2 latency must be less than or equal to
 321          * 100 microseconds.
 322          */
 323         if (acpi_gbl_FADT.c2_latency > ACPI_PROCESSOR_MAX_C2_LATENCY) {
 324                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 325                         "C2 latency too large [%d]\n", acpi_gbl_FADT.c2_latency));
 326                 /* invalidate C2 */
 327                 pr->power.states[ACPI_STATE_C2].address = 0;
 328         }
 329
 330         /*
 331          * FADT supplied C3 latency must be less than or equal to
 332          * 1000 microseconds.
 333          */
 334         if (acpi_gbl_FADT.c3_latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
 335                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 336                         "C3 latency too large [%d]\n", acpi_gbl_FADT.c3_latency));
 337                 /* invalidate C3 */
 338                 pr->power.states[ACPI_STATE_C3].address = 0;
 339         }
 340
 341         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 342                           "lvl2[0x%08x] lvl3[0x%08x]\n",
 343                           pr->power.states[ACPI_STATE_C2].address,
 344                           pr->power.states[ACPI_STATE_C3].address));
 345
 346         return 0;
 347 }
 348
 349 static int acpi_processor_get_power_info_default(struct acpi_processor *pr)
 350 {
 351         if (!pr->power.states[ACPI_STATE_C1].valid) {
 352                 /* set the first C-State to C1 */
 353                 /* all processors need to support C1 */
 354                 pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
 355                 pr->power.states[ACPI_STATE_C1].valid = 1;
 356                 pr->power.states[ACPI_STATE_C1].entry_method = ACPI_CSTATE_HALT;
 357         }
 358         /* the C0 state only exists as a filler in our array */
 359         pr->power.states[ACPI_STATE_C0].valid = 1;
 360         return 0;
 361 }
 362
 363 static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
 364 {
 365         acpi_status status = 0;
 366         u64 count;
 367         int current_count;
 368         int i;
 369         struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
 370         union acpi_object *cst;
 371
 372
 373         if (nocst)
 374                 return -ENODEV;
 375
 376         current_count = 0;
 377
 378         status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
 379         if (ACPI_FAILURE(status)) {
 380                 ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n"));
 381                 return -ENODEV;
 382         }
 383
 384         cst = buffer.pointer;
 385
 386         /* There must be at least 2 elements */
 387         if (!cst || (cst->type != ACPI_TYPE_PACKAGE) || cst->package.count < 2) {
 388                 printk(KERN_ERR PREFIX "not enough elements in _CST\n");
 389                 status = -EFAULT;
 390                 goto end;
 391         }
 392
 393         count = cst->package.elements[0].integer.value;
 394
 395         /* Validate number of power states. */
 396         if (count < 1 || count != cst->package.count - 1) {
 397                 printk(KERN_ERR PREFIX "count given by _CST is not valid\n");
 398                 status = -EFAULT;
 399                 goto end;
 400         }
 401
 402         /* Tell driver that at least _CST is supported. */
 403         pr->flags.has_cst = 1;
 404
 405         for (i = 1; i <= count; i++) {
 406                 union acpi_object *element;
 407                 union acpi_object *obj;
 408                 struct acpi_power_register *reg;
 409                 struct acpi_processor_cx cx;
 410
 411                 memset(&cx, 0, sizeof(cx));
 412
 413                 element = &(cst->package.elements[i]);
 414                 if (element->type != ACPI_TYPE_PACKAGE)
 415                         continue;
 416
 417                 if (element->package.count != 4)
 418                         continue;
 419
 420                 obj = &(element->package.elements[0]);
 421
 422                 if (obj->type != ACPI_TYPE_BUFFER)
 423                         continue;
 424
 425                 reg = (struct acpi_power_register *)obj->buffer.pointer;
 426
 427                 if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
 428                     (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
 429                         continue;
 430
 431                 /* There should be an easy way to extract an integer... */
 432                 obj = &(element->package.elements[1]);
 433                 if (obj->type != ACPI_TYPE_INTEGER)
 434                         continue;
 435
 436                 cx.type = obj->integer.value;
 437                 /*
 438                  * Some buggy BIOSes won't list C1 in _CST -
 439                  * Let acpi_processor_get_power_info_default() handle them later
 440                  */
 441                 if (i == 1 && cx.type != ACPI_STATE_C1)
 442                         current_count++;
 443
 444                 cx.address = reg->address;
 445                 cx.index = current_count + 1;
 446
 447                 cx.entry_method = ACPI_CSTATE_SYSTEMIO;
 448                 if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
 449                         if (acpi_processor_ffh_cstate_probe
 450                                         (pr->id, &cx, reg) == 0) {
 451                                 cx.entry_method = ACPI_CSTATE_FFH;
 452                         } else if (cx.type == ACPI_STATE_C1) {
 453                                 /*
 454                                  * C1 is a special case where FIXED_HARDWARE
 455                                  * can be handled in non-MWAIT way as well.
 456                                  * In that case, save this _CST entry info.
 457                                  * Otherwise, ignore this info and continue.
 458                                  */
 459                                 cx.entry_method = ACPI_CSTATE_HALT;
 460                                 snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
 461                         } else {
 462                                 continue;
 463                         }
 464                         if (cx.type == ACPI_STATE_C1 &&
 465                             (boot_option_idle_override == IDLE_NOMWAIT)) {
 466                                 /*
 467                                  * In most cases the C1 space_id obtained from
 468                                  * _CST object is FIXED_HARDWARE access mode.
 469                                  * But when the option of idle=halt is added,
 470                                  * the entry_method type should be changed from
 471                                  * CSTATE_FFH to CSTATE_HALT.
 472                                  * When the option of idle=nomwait is added,
 473                                  * the C1 entry_method type should be
 474                                  * CSTATE_HALT.
 475                                  */
 476                                 cx.entry_method = ACPI_CSTATE_HALT;
 477                                 snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
 478                         }
 479                 } else {
 480                         snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
 481                                  cx.address);
 482                 }
 483
 484                 if (cx.type == ACPI_STATE_C1) {
 485                         cx.valid = 1;
 486                 }
 487
 488                 obj = &(element->package.elements[2]);
 489                 if (obj->type != ACPI_TYPE_INTEGER)
 490                         continue;
 491
 492                 cx.latency = obj->integer.value;
 493
 494                 obj = &(element->package.elements[3]);
 495                 if (obj->type != ACPI_TYPE_INTEGER)
 496                         continue;
 497
 498                 cx.power = obj->integer.value;
 499
 500                 current_count++;
 501                 memcpy(&(pr->power.states[current_count]), &cx, sizeof(cx));
 502
 503                 /*
 504                  * We support total ACPI_PROCESSOR_MAX_POWER - 1
 505                  * (From 1 through ACPI_PROCESSOR_MAX_POWER - 1)
 506                  */
 507                 if (current_count >= (ACPI_PROCESSOR_MAX_POWER - 1)) {
 508                         printk(KERN_WARNING
 509                                "Limiting number of power states to max (%d)\n",
 510                                ACPI_PROCESSOR_MAX_POWER);
 511                         printk(KERN_WARNING
 512                                "Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n");
 513                         break;
 514                 }
 515         }
 516
 517         ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
 518                           current_count));
 519
 520         /* Validate number of power states discovered */
 521         if (current_count < 2)
 522                 status = -EFAULT;
 523
 524       end:
 525         kfree(buffer.pointer);
 526
 527         return status;
 528 }
 529
 530 static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
 531                                            struct acpi_processor_cx *cx)
 532 {
 533         static int bm_check_flag = -1;
 534         static int bm_control_flag = -1;
 535
 536
 537         if (!cx->address)
 538                 return;
 539
 540         /*
 541          * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
 542          * DMA transfers are used by any ISA device to avoid livelock.
 543          * Note that we could disable Type-F DMA (as recommended by
 544          * the erratum), but this is known to disrupt certain ISA
 545          * devices thus we take the conservative approach.
 546          */
 547         else if (errata.piix4.fdma) {
 548                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 549                                   "C3 not supported on PIIX4 with Type-F DMA\n"));
 550                 return;
 551         }
 552
 553         /* All the logic here assumes flags.bm_check is same across all CPUs */
 554         if (bm_check_flag == -1) {
 555                 /* Determine whether bm_check is needed based on CPU  */
 556                 acpi_processor_power_init_bm_check(&(pr->flags), pr->id);
 557                 bm_check_flag = pr->flags.bm_check;
 558                 bm_control_flag = pr->flags.bm_control;
 559         } else {
 560                 pr->flags.bm_check = bm_check_flag;
 561                 pr->flags.bm_control = bm_control_flag;
 562         }
 563
 564         if (pr->flags.bm_check) {
 565                 if (!pr->flags.bm_control) {
 566                         if (pr->flags.has_cst != 1) {
 567                                 /* bus mastering control is necessary */
 568                                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 569                                         "C3 support requires BM control\n"));
 570                                 return;
 571                         } else {
 572                                 /* Here we enter C3 without bus mastering */
 573                                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 574                                         "C3 support without BM control\n"));
 575                         }
 576                 }
 577         } else {
 578                 /*
 579                  * WBINVD should be set in fadt, for C3 state to be
 580                  * supported on when bm_check is not required.
 581                  */
 582                 if (!(acpi_gbl_FADT.flags & ACPI_FADT_WBINVD)) {
 583                         ACPI_DEBUG_PRINT((ACPI_DB_INFO,
 584                                           "Cache invalidation should work properly"
 585                                           " for C3 to be enabled on SMP systems\n"));
 586                         return;
 587                 }
 588         }
 589
 590         /*
 591          * Otherwise we've met all of our C3 requirements.
 592          * Normalize the C3 latency to expidite policy.  Enable
 593          * checking of bus mastering status (bm_check) so we can
 594          * use this in our C3 policy
 595          */
 596         cx->valid = 1;
 597
 598         cx->latency_ticks = cx->latency;
 599         /*
 600          * On older chipsets, BM_RLD needs to be set
 601          * in order for Bus Master activity to wake the
 602          * system from C3.  Newer chipsets handle DMA
 603          * during C3 automatically and BM_RLD is a NOP.
 604          * In either case, the proper way to
 605          * handle BM_RLD is to set it and leave it set.
 606          */
 607         acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
 608
 609         return;
 610 }
 611
 612 static int acpi_processor_power_verify(struct acpi_processor *pr)
 613 {
 614         unsigned int i;
 615         unsigned int working = 0;
 616
 617         pr->power.timer_broadcast_on_state = INT_MAX;
 618
 619         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
 620                 struct acpi_processor_cx *cx = &pr->power.states[i];
 621
 622                 switch (cx->type) {
 623                 case ACPI_STATE_C1:
 624                         cx->valid = 1;
 625                         break;
 626
 627                 case ACPI_STATE_C2:
 628                         if (!cx->address)
 629                                 break;
 630                         cx->valid = 1;
 631                         cx->latency_ticks = cx->latency; /* Normalize latency */
 632                         break;
 633
 634                 case ACPI_STATE_C3:
 635                         acpi_processor_power_verify_c3(pr, cx);
 636                         break;
 637                 }
 638                 if (!cx->valid)
 639                         continue;
 640
 641                 lapic_timer_check_state(i, pr, cx);
 642                 tsc_check_state(cx->type);
 643                 working++;
 644         }
 645
 646         lapic_timer_propagate_broadcast(pr);
 647
 648         return (working);
 649 }
 650
 651 static int acpi_processor_get_power_info(struct acpi_processor *pr)
 652 {
 653         unsigned int i;
 654         int result;
 655
 656
 657         /* NOTE: the idle thread may not be running while calling
 658          * this function */
 659
 660         /* Zero initialize all the C-states info. */
 661         memset(pr->power.states, 0, sizeof(pr->power.states));
 662
 663         result = acpi_processor_get_power_info_cst(pr);
 664         if (result == -ENODEV)
 665                 result = acpi_processor_get_power_info_fadt(pr);
 666
 667         if (result)
 668                 return result;
 669
 670         acpi_processor_get_power_info_default(pr);
 671
 672         pr->power.count = acpi_processor_power_verify(pr);
 673
 674         /*
 675          * if one state of type C2 or C3 is available, mark this
 676          * CPU as being "idle manageable"
 677          */
 678         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
 679                 if (pr->power.states[i].valid) {
 680                         pr->power.count = i;
 681                         if (pr->power.states[i].type >= ACPI_STATE_C2)
 682                                 pr->flags.power = 1;
 683                 }
 684         }
 685
 686         return 0;
 687 }
 688
 689 /**
 690  * acpi_idle_bm_check - checks if bus master activity was detected
 691  */
 692 static int acpi_idle_bm_check(void)
 693 {
 694         u32 bm_status = 0;
 695
 696         if (bm_check_disable)
 697                 return 0;
 698
 699         acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
 700         if (bm_status)
 701                 acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
 702         /*
 703          * PIIX4 Erratum #18: Note that BM_STS doesn't always reflect
 704          * the true state of bus mastering activity; forcing us to
 705          * manually check the BMIDEA bit of each IDE channel.
 706          */
 707         else if (errata.piix4.bmisx) {
 708                 if ((inb_p(errata.piix4.bmisx + 0x02) & 0x01)
 709                     || (inb_p(errata.piix4.bmisx + 0x0A) & 0x01))
 710                         bm_status = 1;
 711         }
 712         return bm_status;
 713 }
 714
 715 /**
 716  * acpi_idle_do_entry - a helper function that does C2 and C3 type entry
 717  * @cx: cstate data
 718  *
 719  * Caller disables interrupt before call and enables interrupt after return.
 720  */
 721 static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
 722 {
 723         /* Don't trace irqs off for idle */
 724         stop_critical_timings();
 725         if (cx->entry_method == ACPI_CSTATE_FFH) {
 726                 /* Call into architectural FFH based C-state */
 727                 acpi_processor_ffh_cstate_enter(cx);
 728         } else if (cx->entry_method == ACPI_CSTATE_HALT) {
 729                 acpi_safe_halt();
 730         } else {
 731                 /* IO port based C-state */
 732                 inb(cx->address);
 733                 /* Dummy wait op - must do something useless after P_LVL2 read
 734                    because chipsets cannot guarantee that STPCLK# signal
 735                    gets asserted in time to freeze execution properly. */
 736                 inl(acpi_gbl_FADT.xpm_timer_block.address);
 737         }
 738         start_critical_timings();
 739 }
 740
 741 /**
 742  * acpi_idle_enter_c1 - enters an ACPI C1 state-type
 743  * @dev: the target CPU
 744  * @drv: cpuidle driver containing cpuidle state info
 745  * @index: index of target state
 746  *
 747  * This is equivalent to the HALT instruction.
 748  */
 749 static int acpi_idle_enter_c1(struct cpuidle_device *dev,
 750                 struct cpuidle_driver *drv, int index)
 751 {
 752         ktime_t  kt1, kt2;
 753         s64 idle_time;
 754         struct acpi_processor *pr;
 755         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 756         struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
 757
 758         pr = __this_cpu_read(processors);
 759         dev->last_residency = 0;
 760
 761         if (unlikely(!pr))
 762                 return -EINVAL;
 763
 764         local_irq_disable();
 765
 766         if (acpi_idle_suspend) {
 767                 local_irq_enable();
 768                 cpu_relax();
 769                 return -EBUSY;
 770         }
 771
 772         lapic_timer_state_broadcast(pr, cx, 1);
 773         kt1 = ktime_get_real();
 774         acpi_idle_do_entry(cx);
 775         kt2 = ktime_get_real();
 776         idle_time =  ktime_to_us(ktime_sub(kt2, kt1));
 777
 778         /* Update device last_residency*/
 779         dev->last_residency = (int)idle_time;
 780
 781         local_irq_enable();
 782         cx->usage++;
 783         lapic_timer_state_broadcast(pr, cx, 0);
 784
 785         return index;
 786 }
 787
 788
 789 /**
 790  * acpi_idle_play_dead - enters an ACPI state for long-term idle (i.e. off-lining)
 791  * @dev: the target CPU
 792  * @index: the index of suggested state
 793  */
 794 static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
 795 {
 796         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 797         struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
 798
 799         ACPI_FLUSH_CPU_CACHE();
 800
 801         while (1) {
 802
 803                 if (cx->entry_method == ACPI_CSTATE_HALT)
 804                         safe_halt();
 805                 else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
 806                         inb(cx->address);
 807                         /* See comment in acpi_idle_do_entry() */
 808                         inl(acpi_gbl_FADT.xpm_timer_block.address);
 809                 } else
 810                         return -ENODEV;
 811         }
 812
 813         /* Never reached */
 814         return 0;
 815 }
 816
 817 /**
 818  * acpi_idle_enter_simple - enters an ACPI state without BM handling
 819  * @dev: the target CPU
 820  * @drv: cpuidle driver with cpuidle state information
 821  * @index: the index of suggested state
 822  */
 823 static int acpi_idle_enter_simple(struct cpuidle_device *dev,
 824                 struct cpuidle_driver *drv, int index)
 825 {
 826         struct acpi_processor *pr;
 827         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 828         struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
 829         ktime_t  kt1, kt2;
 830         s64 idle_time_ns;
 831         s64 idle_time;
 832
 833         pr = __this_cpu_read(processors);
 834         dev->last_residency = 0;
 835
 836         if (unlikely(!pr))
 837                 return -EINVAL;
 838
 839         local_irq_disable();
 840
 841         if (acpi_idle_suspend) {
 842                 local_irq_enable();
 843                 cpu_relax();
 844                 return -EBUSY;
 845         }
 846
 847         if (cx->entry_method != ACPI_CSTATE_FFH) {
 848                 current_thread_info()->status &= ~TS_POLLING;
 849                 /*
 850                  * TS_POLLING-cleared state must be visible before we test
 851                  * NEED_RESCHED:
 852                  */
 853                 smp_mb();
 854
 855                 if (unlikely(need_resched())) {
 856                         current_thread_info()->status |= TS_POLLING;
 857                         local_irq_enable();
 858                         return -EINVAL;
 859                 }
 860         }
 861
 862         /*
 863          * Must be done before busmaster disable as we might need to
 864          * access HPET !
 865          */
 866         lapic_timer_state_broadcast(pr, cx, 1);
 867
 868         if (cx->type == ACPI_STATE_C3)
 869                 ACPI_FLUSH_CPU_CACHE();
 870
 871         kt1 = ktime_get_real();
 872         /* Tell the scheduler that we are going deep-idle: */
 873         sched_clock_idle_sleep_event();
 874         acpi_idle_do_entry(cx);
 875         kt2 = ktime_get_real();
 876         idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
 877         idle_time = idle_time_ns;
 878         do_div(idle_time, NSEC_PER_USEC);
 879
 880         /* Update device last_residency*/
 881         dev->last_residency = (int)idle_time;
 882
 883         /* Tell the scheduler how much we idled: */
 884         sched_clock_idle_wakeup_event(idle_time_ns);
 885
 886         local_irq_enable();
 887         if (cx->entry_method != ACPI_CSTATE_FFH)
 888                 current_thread_info()->status |= TS_POLLING;
 889
 890         cx->usage++;
 891
 892         lapic_timer_state_broadcast(pr, cx, 0);
 893         cx->time += idle_time;
 894         return index;
 895 }
 896
 897 static int c3_cpu_count;
 898 static DEFINE_RAW_SPINLOCK(c3_lock);
 899
 900 /**
 901  * acpi_idle_enter_bm - enters C3 with proper BM handling
 902  * @dev: the target CPU
 903  * @drv: cpuidle driver containing state data
 904  * @index: the index of suggested state
 905  *
 906  * If BM is detected, the deepest non-C3 idle state is entered instead.
 907  */
 908 static int acpi_idle_enter_bm(struct cpuidle_device *dev,
 909                 struct cpuidle_driver *drv, int index)
 910 {
 911         struct acpi_processor *pr;
 912         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 913         struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
 914         ktime_t  kt1, kt2;
 915         s64 idle_time_ns;
 916         s64 idle_time;
 917
 918
 919         pr = __this_cpu_read(processors);
 920         dev->last_residency = 0;
 921
 922         if (unlikely(!pr))
 923                 return -EINVAL;
 924
 925         if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
 926                 if (drv->safe_state_index >= 0) {
 927                         return drv->states[drv->safe_state_index].enter(dev,
 928                                                 drv, drv->safe_state_index);
 929                 } else {
 930                         local_irq_disable();
 931                         if (!acpi_idle_suspend)
 932                                 acpi_safe_halt();
 933                         local_irq_enable();
 934                         return -EBUSY;
 935                 }
 936         }
 937
 938         local_irq_disable();
 939
 940         if (acpi_idle_suspend) {
 941                 local_irq_enable();
 942                 cpu_relax();
 943                 return -EBUSY;
 944         }
 945
 946         if (cx->entry_method != ACPI_CSTATE_FFH) {
 947                 current_thread_info()->status &= ~TS_POLLING;
 948                 /*
 949                  * TS_POLLING-cleared state must be visible before we test
 950                  * NEED_RESCHED:
 951                  */
 952                 smp_mb();
 953
 954                 if (unlikely(need_resched())) {
 955                         current_thread_info()->status |= TS_POLLING;
 956                         local_irq_enable();
 957                         return -EINVAL;
 958                 }
 959         }
 960
 961         acpi_unlazy_tlb(smp_processor_id());
 962
 963         /* Tell the scheduler that we are going deep-idle: */
 964         sched_clock_idle_sleep_event();
 965         /*
 966          * Must be done before busmaster disable as we might need to
 967          * access HPET !
 968          */
 969         lapic_timer_state_broadcast(pr, cx, 1);
 970
 971         kt1 = ktime_get_real();
 972         /*
 973          * disable bus master
 974          * bm_check implies we need ARB_DIS
 975          * !bm_check implies we need cache flush
 976          * bm_control implies whether we can do ARB_DIS
 977          *
 978          * That leaves a case where bm_check is set and bm_control is
 979          * not set. In that case we cannot do much, we enter C3
 980          * without doing anything.
 981          */
 982         if (pr->flags.bm_check && pr->flags.bm_control) {
 983                 raw_spin_lock(&c3_lock);
 984                 c3_cpu_count++;
 985                 /* Disable bus master arbitration when all CPUs are in C3 */
 986                 if (c3_cpu_count == num_online_cpus())
 987                         acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
 988                 raw_spin_unlock(&c3_lock);
 989         } else if (!pr->flags.bm_check) {
 990                 ACPI_FLUSH_CPU_CACHE();
 991         }
 992
 993         acpi_idle_do_entry(cx);
 994
 995         /* Re-enable bus master arbitration */
 996         if (pr->flags.bm_check && pr->flags.bm_control) {
 997                 raw_spin_lock(&c3_lock);
 998                 acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
 999                 c3_cpu_count--;
1000                 raw_spin_unlock(&c3_lock);
1001         }
1002         kt2 = ktime_get_real();
1003         idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
1004         idle_time = idle_time_ns;
1005         do_div(idle_time, NSEC_PER_USEC);
1006
1007         /* Update device last_residency*/
1008         dev->last_residency = (int)idle_time;
1009
1010         /* Tell the scheduler how much we idled: */
1011         sched_clock_idle_wakeup_event(idle_time_ns);
1012
1013         local_irq_enable();
1014         if (cx->entry_method != ACPI_CSTATE_FFH)
1015                 current_thread_info()->status |= TS_POLLING;
1016
1017         cx->usage++;
1018
1019         lapic_timer_state_broadcast(pr, cx, 0);
1020         cx->time += idle_time;
1021         return index;
1022 }
1023
1024 struct cpuidle_driver acpi_idle_driver = {
1025         .name =         "acpi_idle",
1026         .owner =        THIS_MODULE,
1027 };
1028
1029 /**
1030  * acpi_processor_setup_cpuidle_cx - prepares and configures CPUIDLE
1031  * device i.e. per-cpu data
1032  *
1033  * @pr: the ACPI processor
1034  */
1035 static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr)
1036 {
1037         int i, count = CPUIDLE_DRIVER_STATE_START;
1038         struct acpi_processor_cx *cx;
1039         struct cpuidle_state_usage *state_usage;
1040         struct cpuidle_device *dev = &pr->power.dev;
1041
1042         if (!pr->flags.power_setup_done)
1043                 return -EINVAL;
1044
1045         if (pr->flags.power == 0) {
1046                 return -EINVAL;
1047         }
1048
1049         dev->cpu = pr->id;
1050
1051         if (max_cstate == 0)
1052                 max_cstate = 1;
1053
1054         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
1055                 cx = &pr->power.states[i];
1056                 state_usage = &dev->states_usage[count];
1057
1058                 if (!cx->valid)
1059                         continue;
1060
1061 #ifdef CONFIG_HOTPLUG_CPU
1062                 if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
1063                     !pr->flags.has_cst &&
1064                     !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
1065                         continue;
1066 #endif
1067
1068                 cpuidle_set_statedata(state_usage, cx);
1069
1070                 count++;
1071                 if (count == CPUIDLE_STATE_MAX)
1072                         break;
1073         }
1074
1075         dev->state_count = count;
1076
1077         if (!count)
1078                 return -EINVAL;
1079
1080         return 0;
1081 }
1082
1083 /**
1084  * acpi_processor_setup_cpuidle states- prepares and configures cpuidle
1085  * global state data i.e. idle routines
1086  *
1087  * @pr: the ACPI processor
1088  */
1089 static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
1090 {
1091         int i, count = CPUIDLE_DRIVER_STATE_START;
1092         struct acpi_processor_cx *cx;
1093         struct cpuidle_state *state;
1094         struct cpuidle_driver *drv = &acpi_idle_driver;
1095
1096         if (!pr->flags.power_setup_done)
1097                 return -EINVAL;
1098
1099         if (pr->flags.power == 0)
1100                 return -EINVAL;
1101
1102         drv->safe_state_index = -1;
1103         for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
1104                 drv->states[i].name[0] = '\0';
1105                 drv->states[i].desc[0] = '\0';
1106         }
1107
1108         if (max_cstate == 0)
1109                 max_cstate = 1;
1110
1111         for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
1112                 cx = &pr->power.states[i];
1113
1114                 if (!cx->valid)
1115                         continue;
1116
1117 #ifdef CONFIG_HOTPLUG_CPU
1118                 if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
1119                     !pr->flags.has_cst &&
1120                     !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
1121                         continue;
1122 #endif
1123
1124                 state = &drv->states[count];
1125                 snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
1126                 strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
1127                 state->exit_latency = cx->latency;
1128                 state->target_residency = cx->latency * latency_factor;
1129
1130                 state->flags = 0;
1131                 switch (cx->type) {
1132                         case ACPI_STATE_C1:
1133                         if (cx->entry_method == ACPI_CSTATE_FFH)
1134                                 state->flags |= CPUIDLE_FLAG_TIME_VALID;
1135
1136                         state->enter = acpi_idle_enter_c1;
1137                         state->enter_dead = acpi_idle_play_dead;
1138                         drv->safe_state_index = count;
1139                         break;
1140
1141                         case ACPI_STATE_C2:
1142                         state->flags |= CPUIDLE_FLAG_TIME_VALID;
1143                         state->enter = acpi_idle_enter_simple;
1144                         state->enter_dead = acpi_idle_play_dead;
1145                         drv->safe_state_index = count;
1146                         break;
1147
1148                         case ACPI_STATE_C3:
1149                         state->flags |= CPUIDLE_FLAG_TIME_VALID;
1150                         state->enter = pr->flags.bm_check ?
1151                                         acpi_idle_enter_bm :
1152                                         acpi_idle_enter_simple;
1153                         break;
1154                 }
1155
1156                 count++;
1157                 if (count == CPUIDLE_STATE_MAX)
1158                         break;
1159         }
1160
1161         drv->state_count = count;
1162
1163         if (!count)
1164                 return -EINVAL;
1165
1166         return 0;
1167 }
1168
1169 int acpi_processor_hotplug(struct acpi_processor *pr)
1170 {
1171         int ret = 0;
1172
1173         if (disabled_by_idle_boot_param())
1174                 return 0;
1175
1176         if (!pr)
1177                 return -EINVAL;
1178
1179         if (nocst) {
1180                 return -ENODEV;
1181         }
1182
1183         if (!pr->flags.power_setup_done)
1184                 return -ENODEV;
1185
1186         cpuidle_pause_and_lock();
1187         cpuidle_disable_device(&pr->power.dev);
1188         acpi_processor_get_power_info(pr);
1189         if (pr->flags.power) {
1190                 acpi_processor_setup_cpuidle_cx(pr);
1191                 ret = cpuidle_enable_device(&pr->power.dev);
1192         }
1193         cpuidle_resume_and_unlock();
1194
1195         return ret;
1196 }
1197
1198 int acpi_processor_cst_has_changed(struct acpi_processor *pr)
1199 {
1200         int cpu;
1201         struct acpi_processor *_pr;
1202
1203         if (disabled_by_idle_boot_param())
1204                 return 0;
1205
1206         if (!pr)
1207                 return -EINVAL;
1208
1209         if (nocst)
1210                 return -ENODEV;
1211
1212         if (!pr->flags.power_setup_done)
1213                 return -ENODEV;
1214
1215         /*
1216          * FIXME:  Design the ACPI notification to make it once per
1217          * system instead of once per-cpu.  This condition is a hack
1218          * to make the code that updates C-States be called once.
1219          */
1220
1221         if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) {
1222
1223                 cpuidle_pause_and_lock();
1224                 /* Protect against cpu-hotplug */
1225                 get_online_cpus();
1226
1227                 /* Disable all cpuidle devices */
1228                 for_each_online_cpu(cpu) {
1229                         _pr = per_cpu(processors, cpu);
1230                         if (!_pr || !_pr->flags.power_setup_done)
1231                                 continue;
1232                         cpuidle_disable_device(&_pr->power.dev);
1233                 }
1234
1235                 /* Populate Updated C-state information */
1236                 acpi_processor_setup_cpuidle_states(pr);
1237
1238                 /* Enable all cpuidle devices */
1239                 for_each_online_cpu(cpu) {
1240                         _pr = per_cpu(processors, cpu);
1241                         if (!_pr || !_pr->flags.power_setup_done)
1242                                 continue;
1243                         acpi_processor_get_power_info(_pr);
1244                         if (_pr->flags.power) {
1245                                 acpi_processor_setup_cpuidle_cx(_pr);
1246                                 cpuidle_enable_device(&_pr->power.dev);
1247                         }
1248                 }
1249                 put_online_cpus();
1250                 cpuidle_resume_and_unlock();
1251         }
1252
1253         return 0;
1254 }
1255
1256 static int acpi_processor_registered;
1257
1258 int __cpuinit acpi_processor_power_init(struct acpi_processor *pr,
1259                               struct acpi_device *device)
1260 {
1261         acpi_status status = 0;
1262         int retval;
1263         static int first_run;
1264
1265         if (disabled_by_idle_boot_param())
1266                 return 0;
1267
1268         if (!first_run) {
1269                 dmi_check_system(processor_power_dmi_table);
1270                 max_cstate = acpi_processor_cstate_check(max_cstate);
1271                 if (max_cstate < ACPI_C_STATES_MAX)
1272                         printk(KERN_NOTICE
1273                                "ACPI: processor limited to max C-state %d\n",
1274                                max_cstate);
1275                 first_run++;
1276         }
1277
1278         if (!pr)
1279                 return -EINVAL;
1280
1281         if (acpi_gbl_FADT.cst_control && !nocst) {
1282                 status =
1283                     acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
1284                 if (ACPI_FAILURE(status)) {
1285                         ACPI_EXCEPTION((AE_INFO, status,
1286                                         "Notifying BIOS of _CST ability failed"));
1287                 }
1288         }
1289
1290         acpi_processor_get_power_info(pr);
1291         pr->flags.power_setup_done = 1;
1292
1293         /*
1294          * Install the idle handler if processor power management is supported.
1295          * Note that we use previously set idle handler will be used on
1296          * platforms that only support C1.
1297          */
1298         if (pr->flags.power) {
1299                 /* Register acpi_idle_driver if not already registered */
1300                 if (!acpi_processor_registered) {
1301                         acpi_processor_setup_cpuidle_states(pr);
1302                         retval = cpuidle_register_driver(&acpi_idle_driver);
1303                         if (retval)
1304                                 return retval;
1305                         printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
1306                                         acpi_idle_driver.name);
1307                 }
1308                 /* Register per-cpu cpuidle_device. Cpuidle driver
1309                  * must already be registered before registering device
1310                  */
1311                 acpi_processor_setup_cpuidle_cx(pr);
1312                 retval = cpuidle_register_device(&pr->power.dev);
1313                 if (retval) {
1314                         if (acpi_processor_registered == 0)
1315                                 cpuidle_unregister_driver(&acpi_idle_driver);
1316                         return retval;
1317                 }
1318                 acpi_processor_registered++;
1319         }
1320         return 0;
1321 }
1322
1323 int acpi_processor_power_exit(struct acpi_processor *pr,
1324                               struct acpi_device *device)
1325 {
1326         if (disabled_by_idle_boot_param())
1327                 return 0;
1328
1329         if (pr->flags.power) {
1330                 cpuidle_unregister_device(&pr->power.dev);
1331                 acpi_processor_registered--;
1332                 if (acpi_processor_registered == 0)
1333                         cpuidle_unregister_driver(&acpi_idle_driver);
1334         }
1335
1336         pr->flags.power_setup_done = 0;
1337         return 0;
1338 }