linux/drivers/idle/intel_idle.c
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   1/*
   2 * intel_idle.c - native hardware idle loop for modern Intel processors
   3 *
   4 * Copyright (c) 2010, Intel Corporation.
   5 * Len Brown <len.brown@intel.com>
   6 *
   7 * This program is free software; you can redistribute it and/or modify it
   8 * under the terms and conditions of the GNU General Public License,
   9 * version 2, as published by the Free Software Foundation.
  10 *
  11 * This program is distributed in the hope it will be useful, but WITHOUT
  12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14 * more details.
  15 *
  16 * You should have received a copy of the GNU General Public License along with
  17 * this program; if not, write to the Free Software Foundation, Inc.,
  18 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
  19 */
  20
  21/*
  22 * intel_idle is a cpuidle driver that loads on specific Intel processors
  23 * in lieu of the legacy ACPI processor_idle driver.  The intent is to
  24 * make Linux more efficient on these processors, as intel_idle knows
  25 * more than ACPI, as well as make Linux more immune to ACPI BIOS bugs.
  26 */
  27
  28/*
  29 * Design Assumptions
  30 *
  31 * All CPUs have same idle states as boot CPU
  32 *
  33 * Chipset BM_STS (bus master status) bit is a NOP
  34 *      for preventing entry into deep C-stats
  35 */
  36
  37/*
  38 * Known limitations
  39 *
  40 * The driver currently initializes for_each_online_cpu() upon modprobe.
  41 * It it unaware of subsequent processors hot-added to the system.
  42 * This means that if you boot with maxcpus=n and later online
  43 * processors above n, those processors will use C1 only.
  44 *
  45 * ACPI has a .suspend hack to turn off deep c-statees during suspend
  46 * to avoid complications with the lapic timer workaround.
  47 * Have not seen issues with suspend, but may need same workaround here.
  48 *
  49 * There is currently no kernel-based automatic probing/loading mechanism
  50 * if the driver is built as a module.
  51 */
  52
  53/* un-comment DEBUG to enable pr_debug() statements */
  54#define DEBUG
  55
  56#include <linux/kernel.h>
  57#include <linux/cpuidle.h>
  58#include <linux/clockchips.h>
  59#include <trace/events/power.h>
  60#include <linux/sched.h>
  61#include <linux/notifier.h>
  62#include <linux/cpu.h>
  63#include <linux/module.h>
  64#include <asm/cpu_device_id.h>
  65#include <asm/mwait.h>
  66#include <asm/msr.h>
  67
  68#define INTEL_IDLE_VERSION "0.4"
  69#define PREFIX "intel_idle: "
  70
  71static struct cpuidle_driver intel_idle_driver = {
  72        .name = "intel_idle",
  73        .owner = THIS_MODULE,
  74        .en_core_tk_irqen = 1,
  75};
  76/* intel_idle.max_cstate=0 disables driver */
  77static int max_cstate = MWAIT_MAX_NUM_CSTATES - 1;
  78
  79static unsigned int mwait_substates;
  80
  81#define LAPIC_TIMER_ALWAYS_RELIABLE 0xFFFFFFFF
  82/* Reliable LAPIC Timer States, bit 1 for C1 etc.  */
  83static unsigned int lapic_timer_reliable_states = (1 << 1);      /* Default to only C1 */
  84
  85struct idle_cpu {
  86        struct cpuidle_state *state_table;
  87
  88        /*
  89         * Hardware C-state auto-demotion may not always be optimal.
  90         * Indicate which enable bits to clear here.
  91         */
  92        unsigned long auto_demotion_disable_flags;
  93};
  94
  95static const struct idle_cpu *icpu;
  96static struct cpuidle_device __percpu *intel_idle_cpuidle_devices;
  97static int intel_idle(struct cpuidle_device *dev,
  98                        struct cpuidle_driver *drv, int index);
  99static int intel_idle_cpu_init(int cpu);
 100
 101static struct cpuidle_state *cpuidle_state_table;
 102
 103/*
 104 * Set this flag for states where the HW flushes the TLB for us
 105 * and so we don't need cross-calls to keep it consistent.
 106 * If this flag is set, SW flushes the TLB, so even if the
 107 * HW doesn't do the flushing, this flag is safe to use.
 108 */
 109#define CPUIDLE_FLAG_TLB_FLUSHED        0x10000
 110
 111/*
 112 * States are indexed by the cstate number,
 113 * which is also the index into the MWAIT hint array.
 114 * Thus C0 is a dummy.
 115 */
 116static struct cpuidle_state nehalem_cstates[MWAIT_MAX_NUM_CSTATES] = {
 117        { /* MWAIT C0 */ },
 118        { /* MWAIT C1 */
 119                .name = "C1-NHM",
 120                .desc = "MWAIT 0x00",
 121                .flags = CPUIDLE_FLAG_TIME_VALID,
 122                .exit_latency = 3,
 123                .target_residency = 6,
 124                .enter = &intel_idle },
 125        { /* MWAIT C2 */
 126                .name = "C3-NHM",
 127                .desc = "MWAIT 0x10",
 128                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 129                .exit_latency = 20,
 130                .target_residency = 80,
 131                .enter = &intel_idle },
 132        { /* MWAIT C3 */
 133                .name = "C6-NHM",
 134                .desc = "MWAIT 0x20",
 135                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 136                .exit_latency = 200,
 137                .target_residency = 800,
 138                .enter = &intel_idle },
 139};
 140
 141static struct cpuidle_state snb_cstates[MWAIT_MAX_NUM_CSTATES] = {
 142        { /* MWAIT C0 */ },
 143        { /* MWAIT C1 */
 144                .name = "C1-SNB",
 145                .desc = "MWAIT 0x00",
 146                .flags = CPUIDLE_FLAG_TIME_VALID,
 147                .exit_latency = 1,
 148                .target_residency = 1,
 149                .enter = &intel_idle },
 150        { /* MWAIT C2 */
 151                .name = "C3-SNB",
 152                .desc = "MWAIT 0x10",
 153                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 154                .exit_latency = 80,
 155                .target_residency = 211,
 156                .enter = &intel_idle },
 157        { /* MWAIT C3 */
 158                .name = "C6-SNB",
 159                .desc = "MWAIT 0x20",
 160                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 161                .exit_latency = 104,
 162                .target_residency = 345,
 163                .enter = &intel_idle },
 164        { /* MWAIT C4 */
 165                .name = "C7-SNB",
 166                .desc = "MWAIT 0x30",
 167                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 168                .exit_latency = 109,
 169                .target_residency = 345,
 170                .enter = &intel_idle },
 171};
 172
 173static struct cpuidle_state ivb_cstates[MWAIT_MAX_NUM_CSTATES] = {
 174        { /* MWAIT C0 */ },
 175        { /* MWAIT C1 */
 176                .name = "C1-IVB",
 177                .desc = "MWAIT 0x00",
 178                .flags = CPUIDLE_FLAG_TIME_VALID,
 179                .exit_latency = 1,
 180                .target_residency = 1,
 181                .enter = &intel_idle },
 182        { /* MWAIT C2 */
 183                .name = "C3-IVB",
 184                .desc = "MWAIT 0x10",
 185                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 186                .exit_latency = 59,
 187                .target_residency = 156,
 188                .enter = &intel_idle },
 189        { /* MWAIT C3 */
 190                .name = "C6-IVB",
 191                .desc = "MWAIT 0x20",
 192                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 193                .exit_latency = 80,
 194                .target_residency = 300,
 195                .enter = &intel_idle },
 196        { /* MWAIT C4 */
 197                .name = "C7-IVB",
 198                .desc = "MWAIT 0x30",
 199                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 200                .exit_latency = 87,
 201                .target_residency = 300,
 202                .enter = &intel_idle },
 203};
 204
 205static struct cpuidle_state atom_cstates[MWAIT_MAX_NUM_CSTATES] = {
 206        { /* MWAIT C0 */ },
 207        { /* MWAIT C1 */
 208                .name = "C1-ATM",
 209                .desc = "MWAIT 0x00",
 210                .flags = CPUIDLE_FLAG_TIME_VALID,
 211                .exit_latency = 1,
 212                .target_residency = 4,
 213                .enter = &intel_idle },
 214        { /* MWAIT C2 */
 215                .name = "C2-ATM",
 216                .desc = "MWAIT 0x10",
 217                .flags = CPUIDLE_FLAG_TIME_VALID,
 218                .exit_latency = 20,
 219                .target_residency = 80,
 220                .enter = &intel_idle },
 221        { /* MWAIT C3 */ },
 222        { /* MWAIT C4 */
 223                .name = "C4-ATM",
 224                .desc = "MWAIT 0x30",
 225                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 226                .exit_latency = 100,
 227                .target_residency = 400,
 228                .enter = &intel_idle },
 229        { /* MWAIT C5 */ },
 230        { /* MWAIT C6 */
 231                .name = "C6-ATM",
 232                .desc = "MWAIT 0x52",
 233                .flags = CPUIDLE_FLAG_TIME_VALID | CPUIDLE_FLAG_TLB_FLUSHED,
 234                .exit_latency = 140,
 235                .target_residency = 560,
 236                .enter = &intel_idle },
 237};
 238
 239static long get_driver_data(int cstate)
 240{
 241        int driver_data;
 242        switch (cstate) {
 243
 244        case 1: /* MWAIT C1 */
 245                driver_data = 0x00;
 246                break;
 247        case 2: /* MWAIT C2 */
 248                driver_data = 0x10;
 249                break;
 250        case 3: /* MWAIT C3 */
 251                driver_data = 0x20;
 252                break;
 253        case 4: /* MWAIT C4 */
 254                driver_data = 0x30;
 255                break;
 256        case 5: /* MWAIT C5 */
 257                driver_data = 0x40;
 258                break;
 259        case 6: /* MWAIT C6 */
 260                driver_data = 0x52;
 261                break;
 262        default:
 263                driver_data = 0x00;
 264        }
 265        return driver_data;
 266}
 267
 268/**
 269 * intel_idle
 270 * @dev: cpuidle_device
 271 * @drv: cpuidle driver
 272 * @index: index of cpuidle state
 273 *
 274 * Must be called under local_irq_disable().
 275 */
 276static int intel_idle(struct cpuidle_device *dev,
 277                struct cpuidle_driver *drv, int index)
 278{
 279        unsigned long ecx = 1; /* break on interrupt flag */
 280        struct cpuidle_state *state = &drv->states[index];
 281        struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
 282        unsigned long eax = (unsigned long)cpuidle_get_statedata(state_usage);
 283        unsigned int cstate;
 284        int cpu = smp_processor_id();
 285
 286        cstate = (((eax) >> MWAIT_SUBSTATE_SIZE) & MWAIT_CSTATE_MASK) + 1;
 287
 288        /*
 289         * leave_mm() to avoid costly and often unnecessary wakeups
 290         * for flushing the user TLB's associated with the active mm.
 291         */
 292        if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
 293                leave_mm(cpu);
 294
 295        if (!(lapic_timer_reliable_states & (1 << (cstate))))
 296                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &cpu);
 297
 298        stop_critical_timings();
 299        if (!need_resched()) {
 300
 301                __monitor((void *)&current_thread_info()->flags, 0, 0);
 302                smp_mb();
 303                if (!need_resched())
 304                        __mwait(eax, ecx);
 305        }
 306
 307        start_critical_timings();
 308
 309        if (!(lapic_timer_reliable_states & (1 << (cstate))))
 310                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &cpu);
 311
 312        return index;
 313}
 314
 315static void __setup_broadcast_timer(void *arg)
 316{
 317        unsigned long reason = (unsigned long)arg;
 318        int cpu = smp_processor_id();
 319
 320        reason = reason ?
 321                CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;
 322
 323        clockevents_notify(reason, &cpu);
 324}
 325
 326static int cpu_hotplug_notify(struct notifier_block *n,
 327                              unsigned long action, void *hcpu)
 328{
 329        int hotcpu = (unsigned long)hcpu;
 330        struct cpuidle_device *dev;
 331
 332        switch (action & 0xf) {
 333        case CPU_ONLINE:
 334
 335                if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
 336                        smp_call_function_single(hotcpu, __setup_broadcast_timer,
 337                                                 (void *)true, 1);
 338
 339                /*
 340                 * Some systems can hotplug a cpu at runtime after
 341                 * the kernel has booted, we have to initialize the
 342                 * driver in this case
 343                 */
 344                dev = per_cpu_ptr(intel_idle_cpuidle_devices, hotcpu);
 345                if (!dev->registered)
 346                        intel_idle_cpu_init(hotcpu);
 347
 348                break;
 349        }
 350        return NOTIFY_OK;
 351}
 352
 353static struct notifier_block cpu_hotplug_notifier = {
 354        .notifier_call = cpu_hotplug_notify,
 355};
 356
 357static void auto_demotion_disable(void *dummy)
 358{
 359        unsigned long long msr_bits;
 360
 361        rdmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 362        msr_bits &= ~(icpu->auto_demotion_disable_flags);
 363        wrmsrl(MSR_NHM_SNB_PKG_CST_CFG_CTL, msr_bits);
 364}
 365
 366static const struct idle_cpu idle_cpu_nehalem = {
 367        .state_table = nehalem_cstates,
 368        .auto_demotion_disable_flags = NHM_C1_AUTO_DEMOTE | NHM_C3_AUTO_DEMOTE,
 369};
 370
 371static const struct idle_cpu idle_cpu_atom = {
 372        .state_table = atom_cstates,
 373};
 374
 375static const struct idle_cpu idle_cpu_lincroft = {
 376        .state_table = atom_cstates,
 377        .auto_demotion_disable_flags = ATM_LNC_C6_AUTO_DEMOTE,
 378};
 379
 380static const struct idle_cpu idle_cpu_snb = {
 381        .state_table = snb_cstates,
 382};
 383
 384static const struct idle_cpu idle_cpu_ivb = {
 385        .state_table = ivb_cstates,
 386};
 387
 388#define ICPU(model, cpu) \
 389        { X86_VENDOR_INTEL, 6, model, X86_FEATURE_MWAIT, (unsigned long)&cpu }
 390
 391static const struct x86_cpu_id intel_idle_ids[] = {
 392        ICPU(0x1a, idle_cpu_nehalem),
 393        ICPU(0x1e, idle_cpu_nehalem),
 394        ICPU(0x1f, idle_cpu_nehalem),
 395        ICPU(0x25, idle_cpu_nehalem),
 396        ICPU(0x2c, idle_cpu_nehalem),
 397        ICPU(0x2e, idle_cpu_nehalem),
 398        ICPU(0x1c, idle_cpu_atom),
 399        ICPU(0x26, idle_cpu_lincroft),
 400        ICPU(0x2f, idle_cpu_nehalem),
 401        ICPU(0x2a, idle_cpu_snb),
 402        ICPU(0x2d, idle_cpu_snb),
 403        ICPU(0x3a, idle_cpu_ivb),
 404        ICPU(0x3e, idle_cpu_ivb),
 405        {}
 406};
 407MODULE_DEVICE_TABLE(x86cpu, intel_idle_ids);
 408
 409/*
 410 * intel_idle_probe()
 411 */
 412static int intel_idle_probe(void)
 413{
 414        unsigned int eax, ebx, ecx;
 415        const struct x86_cpu_id *id;
 416
 417        if (max_cstate == 0) {
 418                pr_debug(PREFIX "disabled\n");
 419                return -EPERM;
 420        }
 421
 422        id = x86_match_cpu(intel_idle_ids);
 423        if (!id) {
 424                if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
 425                    boot_cpu_data.x86 == 6)
 426                        pr_debug(PREFIX "does not run on family %d model %d\n",
 427                                boot_cpu_data.x86, boot_cpu_data.x86_model);
 428                return -ENODEV;
 429        }
 430
 431        if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
 432                return -ENODEV;
 433
 434        cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
 435
 436        if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 437            !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
 438            !mwait_substates)
 439                        return -ENODEV;
 440
 441        pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
 442
 443        icpu = (const struct idle_cpu *)id->driver_data;
 444        cpuidle_state_table = icpu->state_table;
 445
 446        if (boot_cpu_has(X86_FEATURE_ARAT))     /* Always Reliable APIC Timer */
 447                lapic_timer_reliable_states = LAPIC_TIMER_ALWAYS_RELIABLE;
 448        else
 449                on_each_cpu(__setup_broadcast_timer, (void *)true, 1);
 450
 451        pr_debug(PREFIX "v" INTEL_IDLE_VERSION
 452                " model 0x%X\n", boot_cpu_data.x86_model);
 453
 454        pr_debug(PREFIX "lapic_timer_reliable_states 0x%x\n",
 455                lapic_timer_reliable_states);
 456        return 0;
 457}
 458
 459/*
 460 * intel_idle_cpuidle_devices_uninit()
 461 * unregister, free cpuidle_devices
 462 */
 463static void intel_idle_cpuidle_devices_uninit(void)
 464{
 465        int i;
 466        struct cpuidle_device *dev;
 467
 468        for_each_online_cpu(i) {
 469                dev = per_cpu_ptr(intel_idle_cpuidle_devices, i);
 470                cpuidle_unregister_device(dev);
 471        }
 472
 473        free_percpu(intel_idle_cpuidle_devices);
 474        return;
 475}
 476/*
 477 * intel_idle_cpuidle_driver_init()
 478 * allocate, initialize cpuidle_states
 479 */
 480static int intel_idle_cpuidle_driver_init(void)
 481{
 482        int cstate;
 483        struct cpuidle_driver *drv = &intel_idle_driver;
 484
 485        drv->state_count = 1;
 486
 487        for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 488                int num_substates;
 489
 490                if (cstate > max_cstate) {
 491                        printk(PREFIX "max_cstate %d reached\n",
 492                                max_cstate);
 493                        break;
 494                }
 495
 496                /* does the state exist in CPUID.MWAIT? */
 497                num_substates = (mwait_substates >> ((cstate) * 4))
 498                                        & MWAIT_SUBSTATE_MASK;
 499                if (num_substates == 0)
 500                        continue;
 501                /* is the state not enabled? */
 502                if (cpuidle_state_table[cstate].enter == NULL) {
 503                        /* does the driver not know about the state? */
 504                        if (*cpuidle_state_table[cstate].name == '\0')
 505                                pr_debug(PREFIX "unaware of model 0x%x"
 506                                        " MWAIT %d please"
 507                                        " contact lenb@kernel.org\n",
 508                                boot_cpu_data.x86_model, cstate);
 509                        continue;
 510                }
 511
 512                if ((cstate > 2) &&
 513                        !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
 514                        mark_tsc_unstable("TSC halts in idle"
 515                                        " states deeper than C2");
 516
 517                drv->states[drv->state_count] = /* structure copy */
 518                        cpuidle_state_table[cstate];
 519
 520                drv->state_count += 1;
 521        }
 522
 523        if (icpu->auto_demotion_disable_flags)
 524                on_each_cpu(auto_demotion_disable, NULL, 1);
 525
 526        return 0;
 527}
 528
 529
 530/*
 531 * intel_idle_cpu_init()
 532 * allocate, initialize, register cpuidle_devices
 533 * @cpu: cpu/core to initialize
 534 */
 535static int intel_idle_cpu_init(int cpu)
 536{
 537        int cstate;
 538        struct cpuidle_device *dev;
 539
 540        dev = per_cpu_ptr(intel_idle_cpuidle_devices, cpu);
 541
 542        dev->state_count = 1;
 543
 544        for (cstate = 1; cstate < MWAIT_MAX_NUM_CSTATES; ++cstate) {
 545                int num_substates;
 546
 547                if (cstate > max_cstate) {
 548                        printk(PREFIX "max_cstate %d reached\n", max_cstate);
 549                        break;
 550                }
 551
 552                /* does the state exist in CPUID.MWAIT? */
 553                num_substates = (mwait_substates >> ((cstate) * 4))
 554                        & MWAIT_SUBSTATE_MASK;
 555                if (num_substates == 0)
 556                        continue;
 557                /* is the state not enabled? */
 558                if (cpuidle_state_table[cstate].enter == NULL)
 559                        continue;
 560
 561                dev->states_usage[dev->state_count].driver_data =
 562                        (void *)get_driver_data(cstate);
 563
 564                dev->state_count += 1;
 565        }
 566
 567        dev->cpu = cpu;
 568
 569        if (cpuidle_register_device(dev)) {
 570                pr_debug(PREFIX "cpuidle_register_device %d failed!\n", cpu);
 571                intel_idle_cpuidle_devices_uninit();
 572                return -EIO;
 573        }
 574
 575        if (icpu->auto_demotion_disable_flags)
 576                smp_call_function_single(cpu, auto_demotion_disable, NULL, 1);
 577
 578        return 0;
 579}
 580
 581static int __init intel_idle_init(void)
 582{
 583        int retval, i;
 584
 585        /* Do not load intel_idle at all for now if idle= is passed */
 586        if (boot_option_idle_override != IDLE_NO_OVERRIDE)
 587                return -ENODEV;
 588
 589        retval = intel_idle_probe();
 590        if (retval)
 591                return retval;
 592
 593        intel_idle_cpuidle_driver_init();
 594        retval = cpuidle_register_driver(&intel_idle_driver);
 595        if (retval) {
 596                struct cpuidle_driver *drv = cpuidle_get_driver();
 597                printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
 598                        drv ? drv->name : "none");
 599                return retval;
 600        }
 601
 602        intel_idle_cpuidle_devices = alloc_percpu(struct cpuidle_device);
 603        if (intel_idle_cpuidle_devices == NULL)
 604                return -ENOMEM;
 605
 606        for_each_online_cpu(i) {
 607                retval = intel_idle_cpu_init(i);
 608                if (retval) {
 609                        cpuidle_unregister_driver(&intel_idle_driver);
 610                        return retval;
 611                }
 612        }
 613        register_cpu_notifier(&cpu_hotplug_notifier);
 614
 615        return 0;
 616}
 617
 618static void __exit intel_idle_exit(void)
 619{
 620        intel_idle_cpuidle_devices_uninit();
 621        cpuidle_unregister_driver(&intel_idle_driver);
 622
 623
 624        if (lapic_timer_reliable_states != LAPIC_TIMER_ALWAYS_RELIABLE)
 625                on_each_cpu(__setup_broadcast_timer, (void *)false, 1);
 626        unregister_cpu_notifier(&cpu_hotplug_notifier);
 627
 628        return;
 629}
 630
 631module_init(intel_idle_init);
 632module_exit(intel_idle_exit);
 633
 634module_param(max_cstate, int, 0444);
 635
 636MODULE_AUTHOR("Len Brown <len.brown@intel.com>");
 637MODULE_DESCRIPTION("Cpuidle driver for Intel Hardware v" INTEL_IDLE_VERSION);
 638MODULE_LICENSE("GPL");
 639
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