processor_idle.c

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/*
 * processor_idle - idle state submodule to the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
 *  Copyright (C) 2004, 2005 Dominik Brodowski <[email protected]>
 *  Copyright (C) 2004  Anil S Keshavamurthy <[email protected]>
 *              - Added processor hotplug support
 *  Copyright (C) 2005  Venkatesh Pallipadi <[email protected]>
 *              - Added support for C3 on SMP
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or (at
 *  your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful, but
 *  WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/slab.h>
#include <linux/acpi.h>
#include <linux/dmi.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>    /* need_resched() */
#include <linux/pm_qos.h>
#include <linux/clockchips.h>
#include <linux/cpuidle.h>
#include <linux/irqflags.h>

/*
 * Include the apic definitions for x86 to have the APIC timer related defines
 * available also for UP (on SMP it gets magically included via linux/smp.h).
 * asm/acpi.h is not an option, as it would require more include magic. Also
 * creating an empty asm-ia64/apic.h would just trade pest vs. cholera.
 */
#ifdef CONFIG_X86
#include <asm/apic.h>
#endif

#include <asm/io.h>
#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#include <asm/processor.h>

#define PREFIX "ACPI: "

#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_idle");
#define PM_TIMER_TICK_NS        (1000000000ULL/PM_TIMER_FREQUENCY)
#define C2_OVERHEAD         1   /* 1us */
#define C3_OVERHEAD         1   /* 1us */
#define PM_TIMER_TICKS_TO_US(p)     (((p) * 1000)/(PM_TIMER_FREQUENCY/1000))

static unsigned int max_cstate __read_mostly = ACPI_PROCESSOR_MAX_POWER;
module_param(max_cstate, uint, 0000);
static unsigned int nocst __read_mostly;
module_param(nocst, uint, 0000);
static int bm_check_disable __read_mostly;
module_param(bm_check_disable, uint, 0000);

static unsigned int latency_factor __read_mostly = 2;
module_param(latency_factor, uint, 0644);

static DEFINE_PER_CPU(struct cpuidle_device *, acpi_cpuidle_device);

static int disabled_by_idle_boot_param(void)
{
    return boot_option_idle_override == IDLE_POLL ||
        boot_option_idle_override == IDLE_FORCE_MWAIT ||
        boot_option_idle_override == IDLE_HALT;
}

/*
 * IBM ThinkPad R40e crashes mysteriously when going into C2 or C3.
 * For now disable this. Probably a bug somewhere else.
 *
 * To skip this limit, boot/load with a large max_cstate limit.
 */
static int set_max_cstate(const struct dmi_system_id *id)
{
    if (max_cstate > ACPI_PROCESSOR_MAX_POWER)
        return 0;

    printk(KERN_NOTICE PREFIX "%s detected - limiting to C%ld max_cstate."
           " Override with \"processor.max_cstate=%d\"\n", id->ident,
           (long)id->driver_data, ACPI_PROCESSOR_MAX_POWER + 1);

    max_cstate = (long)id->driver_data;

    return 0;
}

/* Actually this shouldn't be __cpuinitdata, would be better to fix the
   callers to only run once -AK */
static struct dmi_system_id __cpuinitdata processor_power_dmi_table[] = {
    { set_max_cstate, "Clevo 5600D", {
      DMI_MATCH(DMI_BIOS_VENDOR,"Phoenix Technologies LTD"),
      DMI_MATCH(DMI_BIOS_VERSION,"SHE845M0.86C.0013.D.0302131307")},
     (void *)2},
    { set_max_cstate, "Pavilion zv5000", {
      DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
      DMI_MATCH(DMI_PRODUCT_NAME,"Pavilion zv5000 (DS502A#ABA)")},
     (void *)1},
    { set_max_cstate, "Asus L8400B", {
      DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
      DMI_MATCH(DMI_PRODUCT_NAME,"L8400B series Notebook PC")},
     (void *)1},
    {},
};


/*
 * Callers should disable interrupts before the call and enable
 * interrupts after return.
 */
static void acpi_safe_halt(void)
{
    current_thread_info()->status &= ~TS_POLLING;
    /*
     * TS_POLLING-cleared state must be visible before we
     * test NEED_RESCHED:
     */
    smp_mb();
    if (!need_resched()) {
        safe_halt();
        local_irq_disable();
    }
    current_thread_info()->status |= TS_POLLING;
}

#ifdef ARCH_APICTIMER_STOPS_ON_C3

/*
 * Some BIOS implementations switch to C3 in the published C2 state.
 * This seems to be a common problem on AMD boxen, but other vendors
 * are affected too. We pick the most conservative approach: we assume
 * that the local APIC stops in both C2 and C3.
 */
static void lapic_timer_check_state(int state, struct acpi_processor *pr,
                   struct acpi_processor_cx *cx)
{
    struct acpi_processor_power *pwr = &pr->power;
    u8 type = local_apic_timer_c2_ok ? ACPI_STATE_C3 : ACPI_STATE_C2;

    if (cpu_has(&cpu_data(pr->id), X86_FEATURE_ARAT))
        return;

    if (amd_e400_c1e_detected)
        type = ACPI_STATE_C1;

    /*
     * Check, if one of the previous states already marked the lapic
     * unstable
     */
    if (pwr->timer_broadcast_on_state < state)
        return;

    if (cx->type >= type)
        pr->power.timer_broadcast_on_state = state;
}

static void __lapic_timer_propagate_broadcast(void *arg)
{
    struct acpi_processor *pr = (struct acpi_processor *) arg;
    unsigned long reason;

    reason = pr->power.timer_broadcast_on_state < INT_MAX ?
        CLOCK_EVT_NOTIFY_BROADCAST_ON : CLOCK_EVT_NOTIFY_BROADCAST_OFF;

    clockevents_notify(reason, &pr->id);
}

static void lapic_timer_propagate_broadcast(struct acpi_processor *pr)
{
    smp_call_function_single(pr->id, __lapic_timer_propagate_broadcast,
                 (void *)pr, 1);
}

/* Power(C) State timer broadcast control */
static void lapic_timer_state_broadcast(struct acpi_processor *pr,
                       struct acpi_processor_cx *cx,
                       int broadcast)
{
    int state = cx - pr->power.states;

    if (state >= pr->power.timer_broadcast_on_state) {
        unsigned long reason;

        reason = broadcast ?  CLOCK_EVT_NOTIFY_BROADCAST_ENTER :
            CLOCK_EVT_NOTIFY_BROADCAST_EXIT;
        clockevents_notify(reason, &pr->id);
    }
}

#else

static void lapic_timer_check_state(int state, struct acpi_processor *pr,
                   struct acpi_processor_cx *cstate) { }
static void lapic_timer_propagate_broadcast(struct acpi_processor *pr) { }
static void lapic_timer_state_broadcast(struct acpi_processor *pr,
                       struct acpi_processor_cx *cx,
                       int broadcast)
{
}

#endif

static u32 saved_bm_rld;

static void acpi_idle_bm_rld_save(void)
{
    acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &saved_bm_rld);
}
static void acpi_idle_bm_rld_restore(void)
{
    u32 resumed_bm_rld;

    acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_RLD, &resumed_bm_rld);

    if (resumed_bm_rld != saved_bm_rld)
        acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, saved_bm_rld);
}

int acpi_processor_suspend(struct device *dev)
{
    acpi_idle_bm_rld_save();
    return 0;
}

int acpi_processor_resume(struct device *dev)
{
    acpi_idle_bm_rld_restore();
    return 0;
}

#if defined(CONFIG_X86)
static void tsc_check_state(int state)
{
    switch (boot_cpu_data.x86_vendor) {
    case X86_VENDOR_AMD:
    case X86_VENDOR_INTEL:
        /*
         * AMD Fam10h TSC will tick in all
         * C/P/S0/S1 states when this bit is set.
         */
        if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
            return;

        /*FALL THROUGH*/
    default:
        /* TSC could halt in idle, so notify users */
        if (state > ACPI_STATE_C1)
            mark_tsc_unstable("TSC halts in idle");
    }
}
#else
static void tsc_check_state(int state) { return; }
#endif

static int acpi_processor_get_power_info_fadt(struct acpi_processor *pr)
{

    if (!pr)
        return -EINVAL;

    if (!pr->pblk)
        return -ENODEV;

    /* if info is obtained from pblk/fadt, type equals state */
    pr->power.states[ACPI_STATE_C2].type = ACPI_STATE_C2;
    pr->power.states[ACPI_STATE_C3].type = ACPI_STATE_C3;

#ifndef CONFIG_HOTPLUG_CPU
    /*
     * Check for P_LVL2_UP flag before entering C2 and above on
     * an SMP system.
     */
    if ((num_online_cpus() > 1) &&
        !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
        return -ENODEV;
#endif

    /* determine C2 and C3 address from pblk */
    pr->power.states[ACPI_STATE_C2].address = pr->pblk + 4;
    pr->power.states[ACPI_STATE_C3].address = pr->pblk + 5;

    /* determine latencies from FADT */
    pr->power.states[ACPI_STATE_C2].latency = acpi_gbl_FADT.c2_latency;
    pr->power.states[ACPI_STATE_C3].latency = acpi_gbl_FADT.c3_latency;

    /*
     * FADT specified C2 latency must be less than or equal to
     * 100 microseconds.
     */
    if (acpi_gbl_FADT.c2_latency > ACPI_PROCESSOR_MAX_C2_LATENCY) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
            "C2 latency too large [%d]\n", acpi_gbl_FADT.c2_latency));
        /* invalidate C2 */
        pr->power.states[ACPI_STATE_C2].address = 0;
    }

    /*
     * FADT supplied C3 latency must be less than or equal to
     * 1000 microseconds.
     */
    if (acpi_gbl_FADT.c3_latency > ACPI_PROCESSOR_MAX_C3_LATENCY) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
            "C3 latency too large [%d]\n", acpi_gbl_FADT.c3_latency));
        /* invalidate C3 */
        pr->power.states[ACPI_STATE_C3].address = 0;
    }

    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
              "lvl2[0x%08x] lvl3[0x%08x]\n",
              pr->power.states[ACPI_STATE_C2].address,
              pr->power.states[ACPI_STATE_C3].address));

    return 0;
}

static int acpi_processor_get_power_info_default(struct acpi_processor *pr)
{
    if (!pr->power.states[ACPI_STATE_C1].valid) {
        /* set the first C-State to C1 */
        /* all processors need to support C1 */
        pr->power.states[ACPI_STATE_C1].type = ACPI_STATE_C1;
        pr->power.states[ACPI_STATE_C1].valid = 1;
        pr->power.states[ACPI_STATE_C1].entry_method = ACPI_CSTATE_HALT;
    }
    /* the C0 state only exists as a filler in our array */
    pr->power.states[ACPI_STATE_C0].valid = 1;
    return 0;
}

static int acpi_processor_get_power_info_cst(struct acpi_processor *pr)
{
    acpi_status status = 0;
    u64 count;
    int current_count;
    int i;
    struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
    union acpi_object *cst;


    if (nocst)
        return -ENODEV;

    current_count = 0;

    status = acpi_evaluate_object(pr->handle, "_CST", NULL, &buffer);
    if (ACPI_FAILURE(status)) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n"));
        return -ENODEV;
    }

    cst = buffer.pointer;

    /* There must be at least 2 elements */
    if (!cst || (cst->type != ACPI_TYPE_PACKAGE) || cst->package.count < 2) {
        printk(KERN_ERR PREFIX "not enough elements in _CST\n");
        status = -EFAULT;
        goto end;
    }

    count = cst->package.elements[0].integer.value;

    /* Validate number of power states. */
    if (count < 1 || count != cst->package.count - 1) {
        printk(KERN_ERR PREFIX "count given by _CST is not valid\n");
        status = -EFAULT;
        goto end;
    }

    /* Tell driver that at least _CST is supported. */
    pr->flags.has_cst = 1;

    for (i = 1; i <= count; i++) {
        union acpi_object *element;
        union acpi_object *obj;
        struct acpi_power_register *reg;
        struct acpi_processor_cx cx;

        memset(&cx, 0, sizeof(cx));

        element = &(cst->package.elements[i]);
        if (element->type != ACPI_TYPE_PACKAGE)
            continue;

        if (element->package.count != 4)
            continue;

        obj = &(element->package.elements[0]);

        if (obj->type != ACPI_TYPE_BUFFER)
            continue;

        reg = (struct acpi_power_register *)obj->buffer.pointer;

        if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO &&
            (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE))
            continue;

        /* There should be an easy way to extract an integer... */
        obj = &(element->package.elements[1]);
        if (obj->type != ACPI_TYPE_INTEGER)
            continue;

        cx.type = obj->integer.value;
        /*
         * Some buggy BIOSes won't list C1 in _CST -
         * Let acpi_processor_get_power_info_default() handle them later
         */
        if (i == 1 && cx.type != ACPI_STATE_C1)
            current_count++;

        cx.address = reg->address;
        cx.index = current_count + 1;

        cx.entry_method = ACPI_CSTATE_SYSTEMIO;
        if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) {
            if (acpi_processor_ffh_cstate_probe
                    (pr->id, &cx, reg) == 0) {
                cx.entry_method = ACPI_CSTATE_FFH;
            } else if (cx.type == ACPI_STATE_C1) {
                /*
                 * C1 is a special case where FIXED_HARDWARE
                 * can be handled in non-MWAIT way as well.
                 * In that case, save this _CST entry info.
                 * Otherwise, ignore this info and continue.
                 */
                cx.entry_method = ACPI_CSTATE_HALT;
                snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
            } else {
                continue;
            }
            if (cx.type == ACPI_STATE_C1 &&
                (boot_option_idle_override == IDLE_NOMWAIT)) {
                /*
                 * In most cases the C1 space_id obtained from
                 * _CST object is FIXED_HARDWARE access mode.
                 * But when the option of idle=halt is added,
                 * the entry_method type should be changed from
                 * CSTATE_FFH to CSTATE_HALT.
                 * When the option of idle=nomwait is added,
                 * the C1 entry_method type should be
                 * CSTATE_HALT.
                 */
                cx.entry_method = ACPI_CSTATE_HALT;
                snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT");
            }
        } else {
            snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x",
                 cx.address);
        }

        if (cx.type == ACPI_STATE_C1) {
            cx.valid = 1;
        }

        obj = &(element->package.elements[2]);
        if (obj->type != ACPI_TYPE_INTEGER)
            continue;

        cx.latency = obj->integer.value;

        obj = &(element->package.elements[3]);
        if (obj->type != ACPI_TYPE_INTEGER)
            continue;

        current_count++;
        memcpy(&(pr->power.states[current_count]), &cx, sizeof(cx));

        /*
         * We support total ACPI_PROCESSOR_MAX_POWER - 1
         * (From 1 through ACPI_PROCESSOR_MAX_POWER - 1)
         */
        if (current_count >= (ACPI_PROCESSOR_MAX_POWER - 1)) {
            printk(KERN_WARNING
                   "Limiting number of power states to max (%d)\n",
                   ACPI_PROCESSOR_MAX_POWER);
            printk(KERN_WARNING
                   "Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n");
            break;
        }
    }

    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d power states\n",
              current_count));

    /* Validate number of power states discovered */
    if (current_count < 2)
        status = -EFAULT;

      end:
    kfree(buffer.pointer);

    return status;
}

static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
                       struct acpi_processor_cx *cx)
{
    static int bm_check_flag = -1;
    static int bm_control_flag = -1;


    if (!cx->address)
        return;

    /*
     * PIIX4 Erratum #18: We don't support C3 when Type-F (fast)
     * DMA transfers are used by any ISA device to avoid livelock.
     * Note that we could disable Type-F DMA (as recommended by
     * the erratum), but this is known to disrupt certain ISA
     * devices thus we take the conservative approach.
     */
    else if (errata.piix4.fdma) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "C3 not supported on PIIX4 with Type-F DMA\n"));
        return;
    }

    /* All the logic here assumes flags.bm_check is same across all CPUs */
    if (bm_check_flag == -1) {
        /* Determine whether bm_check is needed based on CPU  */
        acpi_processor_power_init_bm_check(&(pr->flags), pr->id);
        bm_check_flag = pr->flags.bm_check;
        bm_control_flag = pr->flags.bm_control;
    } else {
        pr->flags.bm_check = bm_check_flag;
        pr->flags.bm_control = bm_control_flag;
    }

    if (pr->flags.bm_check) {
        if (!pr->flags.bm_control) {
            if (pr->flags.has_cst != 1) {
                /* bus mastering control is necessary */
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                    "C3 support requires BM control\n"));
                return;
            } else {
                /* Here we enter C3 without bus mastering */
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                    "C3 support without BM control\n"));
            }
        }
    } else {
        /*
         * WBINVD should be set in fadt, for C3 state to be
         * supported on when bm_check is not required.
         */
        if (!(acpi_gbl_FADT.flags & ACPI_FADT_WBINVD)) {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                      "Cache invalidation should work properly"
                      " for C3 to be enabled on SMP systems\n"));
            return;
        }
    }

    /*
     * Otherwise we've met all of our C3 requirements.
     * Normalize the C3 latency to expidite policy.  Enable
     * checking of bus mastering status (bm_check) so we can
     * use this in our C3 policy
     */
    cx->valid = 1;

    /*
     * On older chipsets, BM_RLD needs to be set
     * in order for Bus Master activity to wake the
     * system from C3.  Newer chipsets handle DMA
     * during C3 automatically and BM_RLD is a NOP.
     * In either case, the proper way to
     * handle BM_RLD is to set it and leave it set.
     */
    acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_RLD, 1);

    return;
}

static int acpi_processor_power_verify(struct acpi_processor *pr)
{
    unsigned int i;
    unsigned int working = 0;

    pr->power.timer_broadcast_on_state = INT_MAX;

    for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
        struct acpi_processor_cx *cx = &pr->power.states[i];

        switch (cx->type) {
        case ACPI_STATE_C1:
            cx->valid = 1;
            break;

        case ACPI_STATE_C2:
            if (!cx->address)
                break;
            cx->valid = 1; 
            break;

        case ACPI_STATE_C3:
            acpi_processor_power_verify_c3(pr, cx);
            break;
        }
        if (!cx->valid)
            continue;

        lapic_timer_check_state(i, pr, cx);
        tsc_check_state(cx->type);
        working++;
    }

    lapic_timer_propagate_broadcast(pr);

    return (working);
}

static int acpi_processor_get_power_info(struct acpi_processor *pr)
{
    unsigned int i;
    int result;


    /* NOTE: the idle thread may not be running while calling
     * this function */

    /* Zero initialize all the C-states info. */
    memset(pr->power.states, 0, sizeof(pr->power.states));

    result = acpi_processor_get_power_info_cst(pr);
    if (result == -ENODEV)
        result = acpi_processor_get_power_info_fadt(pr);

    if (result)
        return result;

    acpi_processor_get_power_info_default(pr);

    pr->power.count = acpi_processor_power_verify(pr);

    /*
     * if one state of type C2 or C3 is available, mark this
     * CPU as being "idle manageable"
     */
    for (i = 1; i < ACPI_PROCESSOR_MAX_POWER; i++) {
        if (pr->power.states[i].valid) {
            pr->power.count = i;
            if (pr->power.states[i].type >= ACPI_STATE_C2)
                pr->flags.power = 1;
        }
    }

    return 0;
}

static int acpi_idle_bm_check(void)
{
    u32 bm_status = 0;

    if (bm_check_disable)
        return 0;

    acpi_read_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
    if (bm_status)
        acpi_write_bit_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
    /*
     * PIIX4 Erratum #18: Note that BM_STS doesn't always reflect
     * the true state of bus mastering activity; forcing us to
     * manually check the BMIDEA bit of each IDE channel.
     */
    else if (errata.piix4.bmisx) {
        if ((inb_p(errata.piix4.bmisx + 0x02) & 0x01)
            || (inb_p(errata.piix4.bmisx + 0x0A) & 0x01))
            bm_status = 1;
    }
    return bm_status;
}

static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
{
    /* Don't trace irqs off for idle */
    stop_critical_timings();
    if (cx->entry_method == ACPI_CSTATE_FFH) {
        /* Call into architectural FFH based C-state */
        acpi_processor_ffh_cstate_enter(cx);
    } else if (cx->entry_method == ACPI_CSTATE_HALT) {
        acpi_safe_halt();
    } else {
        /* IO port based C-state */
        inb(cx->address);
        /* Dummy wait op - must do something useless after P_LVL2 read
           because chipsets cannot guarantee that STPCLK# signal
           gets asserted in time to freeze execution properly. */
        inl(acpi_gbl_FADT.xpm_timer_block.address);
    }
    start_critical_timings();
}

static int acpi_idle_enter_c1(struct cpuidle_device *dev,
        struct cpuidle_driver *drv, int index)
{
    ktime_t  kt1, kt2;
    s64 idle_time;
    struct acpi_processor *pr;
    struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
    struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);

    pr = __this_cpu_read(processors);
    dev->last_residency = 0;

    if (unlikely(!pr))
        return -EINVAL;

    local_irq_disable();


    lapic_timer_state_broadcast(pr, cx, 1);
    kt1 = ktime_get_real();
    acpi_idle_do_entry(cx);
    kt2 = ktime_get_real();
    idle_time =  ktime_to_us(ktime_sub(kt2, kt1));

    /* Update device last_residency*/
    dev->last_residency = (int)idle_time;

    local_irq_enable();
    lapic_timer_state_broadcast(pr, cx, 0);

    return index;
}


static int acpi_idle_play_dead(struct cpuidle_device *dev, int index)
{
    struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
    struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);

    ACPI_FLUSH_CPU_CACHE();

    while (1) {

        if (cx->entry_method == ACPI_CSTATE_HALT)
            safe_halt();
        else if (cx->entry_method == ACPI_CSTATE_SYSTEMIO) {
            inb(cx->address);
            /* See comment in acpi_idle_do_entry() */
            inl(acpi_gbl_FADT.xpm_timer_block.address);
        } else
            return -ENODEV;
    }

    /* Never reached */
    return 0;
}

static int acpi_idle_enter_simple(struct cpuidle_device *dev,
        struct cpuidle_driver *drv, int index)
{
    struct acpi_processor *pr;
    struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
    struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
    ktime_t  kt1, kt2;
    s64 idle_time_ns;
    s64 idle_time;

    pr = __this_cpu_read(processors);
    dev->last_residency = 0;

    if (unlikely(!pr))
        return -EINVAL;

    local_irq_disable();


    if (cx->entry_method != ACPI_CSTATE_FFH) {
        current_thread_info()->status &= ~TS_POLLING;
        /*
         * TS_POLLING-cleared state must be visible before we test
         * NEED_RESCHED:
         */
        smp_mb();

        if (unlikely(need_resched())) {
            current_thread_info()->status |= TS_POLLING;
            local_irq_enable();
            return -EINVAL;
        }
    }

    /*
     * Must be done before busmaster disable as we might need to
     * access HPET !
     */
    lapic_timer_state_broadcast(pr, cx, 1);

    if (cx->type == ACPI_STATE_C3)
        ACPI_FLUSH_CPU_CACHE();

    kt1 = ktime_get_real();
    /* Tell the scheduler that we are going deep-idle: */
    sched_clock_idle_sleep_event();
    acpi_idle_do_entry(cx);
    kt2 = ktime_get_real();
    idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
    idle_time = idle_time_ns;
    do_div(idle_time, NSEC_PER_USEC);

    /* Update device last_residency*/
    dev->last_residency = (int)idle_time;

    /* Tell the scheduler how much we idled: */
    sched_clock_idle_wakeup_event(idle_time_ns);

    local_irq_enable();
    if (cx->entry_method != ACPI_CSTATE_FFH)
        current_thread_info()->status |= TS_POLLING;

    lapic_timer_state_broadcast(pr, cx, 0);
    return index;
}

static int c3_cpu_count;
static DEFINE_RAW_SPINLOCK(c3_lock);

static int acpi_idle_enter_bm(struct cpuidle_device *dev,
        struct cpuidle_driver *drv, int index)
{
    struct acpi_processor *pr;
    struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
    struct acpi_processor_cx *cx = cpuidle_get_statedata(state_usage);
    ktime_t  kt1, kt2;
    s64 idle_time_ns;
    s64 idle_time;


    pr = __this_cpu_read(processors);
    dev->last_residency = 0;

    if (unlikely(!pr))
        return -EINVAL;

    if (!cx->bm_sts_skip && acpi_idle_bm_check()) {
        if (drv->safe_state_index >= 0) {
            return drv->states[drv->safe_state_index].enter(dev,
                        drv, drv->safe_state_index);
        } else {
            local_irq_disable();
            acpi_safe_halt();
            local_irq_enable();
            return -EBUSY;
        }
    }

    local_irq_disable();


    if (cx->entry_method != ACPI_CSTATE_FFH) {
        current_thread_info()->status &= ~TS_POLLING;
        /*
         * TS_POLLING-cleared state must be visible before we test
         * NEED_RESCHED:
         */
        smp_mb();

        if (unlikely(need_resched())) {
            current_thread_info()->status |= TS_POLLING;
            local_irq_enable();
            return -EINVAL;
        }
    }

    acpi_unlazy_tlb(smp_processor_id());

    /* Tell the scheduler that we are going deep-idle: */
    sched_clock_idle_sleep_event();
    /*
     * Must be done before busmaster disable as we might need to
     * access HPET !
     */
    lapic_timer_state_broadcast(pr, cx, 1);

    kt1 = ktime_get_real();
    /*
     * disable bus master
     * bm_check implies we need ARB_DIS
     * !bm_check implies we need cache flush
     * bm_control implies whether we can do ARB_DIS
     *
     * That leaves a case where bm_check is set and bm_control is
     * not set. In that case we cannot do much, we enter C3
     * without doing anything.
     */
    if (pr->flags.bm_check && pr->flags.bm_control) {
        raw_spin_lock(&c3_lock);
        c3_cpu_count++;
        /* Disable bus master arbitration when all CPUs are in C3 */
        if (c3_cpu_count == num_online_cpus())
            acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 1);
        raw_spin_unlock(&c3_lock);
    } else if (!pr->flags.bm_check) {
        ACPI_FLUSH_CPU_CACHE();
    }

    acpi_idle_do_entry(cx);

    /* Re-enable bus master arbitration */
    if (pr->flags.bm_check && pr->flags.bm_control) {
        raw_spin_lock(&c3_lock);
        acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0);
        c3_cpu_count--;
        raw_spin_unlock(&c3_lock);
    }
    kt2 = ktime_get_real();
    idle_time_ns = ktime_to_ns(ktime_sub(kt2, kt1));
    idle_time = idle_time_ns;
    do_div(idle_time, NSEC_PER_USEC);

    /* Update device last_residency*/
    dev->last_residency = (int)idle_time;

    /* Tell the scheduler how much we idled: */
    sched_clock_idle_wakeup_event(idle_time_ns);

    local_irq_enable();
    if (cx->entry_method != ACPI_CSTATE_FFH)
        current_thread_info()->status |= TS_POLLING;

    lapic_timer_state_broadcast(pr, cx, 0);
    return index;
}

struct cpuidle_driver acpi_idle_driver = {
    .name =     "acpi_idle",
    .owner =    THIS_MODULE,
};

static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr)
{
    int i, count = CPUIDLE_DRIVER_STATE_START;
    struct acpi_processor_cx *cx;
    struct cpuidle_state_usage *state_usage;
    struct cpuidle_device *dev = per_cpu(acpi_cpuidle_device, pr->id);

    if (!pr->flags.power_setup_done)
        return -EINVAL;

    if (pr->flags.power == 0) {
        return -EINVAL;
    }

    dev->cpu = pr->id;

    if (max_cstate == 0)
        max_cstate = 1;

    for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
        cx = &pr->power.states[i];
        state_usage = &dev->states_usage[count];

        if (!cx->valid)
            continue;

#ifdef CONFIG_HOTPLUG_CPU
        if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
            !pr->flags.has_cst &&
            !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
            continue;
#endif

        cpuidle_set_statedata(state_usage, cx);

        count++;
        if (count == CPUIDLE_STATE_MAX)
            break;
    }

    dev->state_count = count;

    if (!count)
        return -EINVAL;

    return 0;
}

static int acpi_processor_setup_cpuidle_states(struct acpi_processor *pr)
{
    int i, count = CPUIDLE_DRIVER_STATE_START;
    struct acpi_processor_cx *cx;
    struct cpuidle_state *state;
    struct cpuidle_driver *drv = &acpi_idle_driver;

    if (!pr->flags.power_setup_done)
        return -EINVAL;

    if (pr->flags.power == 0)
        return -EINVAL;

    drv->safe_state_index = -1;
    for (i = 0; i < CPUIDLE_STATE_MAX; i++) {
        drv->states[i].name[0] = '\0';
        drv->states[i].desc[0] = '\0';
    }

    if (max_cstate == 0)
        max_cstate = 1;

    for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
        cx = &pr->power.states[i];

        if (!cx->valid)
            continue;

#ifdef CONFIG_HOTPLUG_CPU
        if ((cx->type != ACPI_STATE_C1) && (num_online_cpus() > 1) &&
            !pr->flags.has_cst &&
            !(acpi_gbl_FADT.flags & ACPI_FADT_C2_MP_SUPPORTED))
            continue;
#endif

        state = &drv->states[count];
        snprintf(state->name, CPUIDLE_NAME_LEN, "C%d", i);
        strncpy(state->desc, cx->desc, CPUIDLE_DESC_LEN);
        state->exit_latency = cx->latency;
        state->target_residency = cx->latency * latency_factor;

        state->flags = 0;
        switch (cx->type) {
            case ACPI_STATE_C1:
            if (cx->entry_method == ACPI_CSTATE_FFH)
                state->flags |= CPUIDLE_FLAG_TIME_VALID;

            state->enter = acpi_idle_enter_c1;
            state->enter_dead = acpi_idle_play_dead;
            drv->safe_state_index = count;
            break;

            case ACPI_STATE_C2:
            state->flags |= CPUIDLE_FLAG_TIME_VALID;
            state->enter = acpi_idle_enter_simple;
            state->enter_dead = acpi_idle_play_dead;
            drv->safe_state_index = count;
            break;

            case ACPI_STATE_C3:
            state->flags |= CPUIDLE_FLAG_TIME_VALID;
            state->enter = pr->flags.bm_check ?
                    acpi_idle_enter_bm :
                    acpi_idle_enter_simple;
            break;
        }

        count++;
        if (count == CPUIDLE_STATE_MAX)
            break;
    }

    drv->state_count = count;

    if (!count)
        return -EINVAL;

    return 0;
}

int acpi_processor_hotplug(struct acpi_processor *pr)
{
    int ret = 0;
    struct cpuidle_device *dev;

    if (disabled_by_idle_boot_param())
        return 0;

    if (!pr)
        return -EINVAL;

    if (nocst) {
        return -ENODEV;
    }

    if (!pr->flags.power_setup_done)
        return -ENODEV;

    dev = per_cpu(acpi_cpuidle_device, pr->id);
    cpuidle_pause_and_lock();
    cpuidle_disable_device(dev);
    acpi_processor_get_power_info(pr);
    if (pr->flags.power) {
        acpi_processor_setup_cpuidle_cx(pr);
        ret = cpuidle_enable_device(dev);
    }
    cpuidle_resume_and_unlock();

    return ret;
}

int acpi_processor_cst_has_changed(struct acpi_processor *pr)
{
    int cpu;
    struct acpi_processor *_pr;
    struct cpuidle_device *dev;

    if (disabled_by_idle_boot_param())
        return 0;

    if (!pr)
        return -EINVAL;

    if (nocst)
        return -ENODEV;

    if (!pr->flags.power_setup_done)
        return -ENODEV;

    /*
     * FIXME:  Design the ACPI notification to make it once per
     * system instead of once per-cpu.  This condition is a hack
     * to make the code that updates C-States be called once.
     */

    if (pr->id == 0 && cpuidle_get_driver() == &acpi_idle_driver) {

        cpuidle_pause_and_lock();
        /* Protect against cpu-hotplug */
        get_online_cpus();

        /* Disable all cpuidle devices */
        for_each_online_cpu(cpu) {
            _pr = per_cpu(processors, cpu);
            if (!_pr || !_pr->flags.power_setup_done)
                continue;
            dev = per_cpu(acpi_cpuidle_device, cpu);
            cpuidle_disable_device(dev);
        }

        /* Populate Updated C-state information */
        acpi_processor_setup_cpuidle_states(pr);

        /* Enable all cpuidle devices */
        for_each_online_cpu(cpu) {
            _pr = per_cpu(processors, cpu);
            if (!_pr || !_pr->flags.power_setup_done)
                continue;
            acpi_processor_get_power_info(_pr);
            if (_pr->flags.power) {
                acpi_processor_setup_cpuidle_cx(_pr);
                dev = per_cpu(acpi_cpuidle_device, cpu);
                cpuidle_enable_device(dev);
            }
        }
        put_online_cpus();
        cpuidle_resume_and_unlock();
    }

    return 0;
}

static int acpi_processor_registered;

int __cpuinit acpi_processor_power_init(struct acpi_processor *pr)
{
    acpi_status status = 0;
    int retval;
    struct cpuidle_device *dev;
    static int first_run;

    if (disabled_by_idle_boot_param())
        return 0;

    if (!first_run) {
        dmi_check_system(processor_power_dmi_table);
        max_cstate = acpi_processor_cstate_check(max_cstate);
        if (max_cstate < ACPI_C_STATES_MAX)
            printk(KERN_NOTICE
                   "ACPI: processor limited to max C-state %d\n",
                   max_cstate);
        first_run++;
    }

    if (!pr)
        return -EINVAL;

    if (acpi_gbl_FADT.cst_control && !nocst) {
        status =
            acpi_os_write_port(acpi_gbl_FADT.smi_command, acpi_gbl_FADT.cst_control, 8);
        if (ACPI_FAILURE(status)) {
            ACPI_EXCEPTION((AE_INFO, status,
                    "Notifying BIOS of _CST ability failed"));
        }
    }

    acpi_processor_get_power_info(pr);
    pr->flags.power_setup_done = 1;

    /*
     * Install the idle handler if processor power management is supported.
     * Note that we use previously set idle handler will be used on
     * platforms that only support C1.
     */
    if (pr->flags.power) {
        /* Register acpi_idle_driver if not already registered */
        if (!acpi_processor_registered) {
            acpi_processor_setup_cpuidle_states(pr);
            retval = cpuidle_register_driver(&acpi_idle_driver);
            if (retval)
                return retval;
            printk(KERN_DEBUG "ACPI: %s registered with cpuidle\n",
                    acpi_idle_driver.name);
        }

        dev = kzalloc(sizeof(*dev), GFP_KERNEL);
        if (!dev)
            return -ENOMEM;
        per_cpu(acpi_cpuidle_device, pr->id) = dev;

        acpi_processor_setup_cpuidle_cx(pr);

        /* Register per-cpu cpuidle_device. Cpuidle driver
         * must already be registered before registering device
         */
        retval = cpuidle_register_device(dev);
        if (retval) {
            if (acpi_processor_registered == 0)
                cpuidle_unregister_driver(&acpi_idle_driver);
            return retval;
        }
        acpi_processor_registered++;
    }
    return 0;
}

int acpi_processor_power_exit(struct acpi_processor *pr)
{
    struct cpuidle_device *dev = per_cpu(acpi_cpuidle_device, pr->id);

    if (disabled_by_idle_boot_param())
        return 0;

    if (pr->flags.power) {
        cpuidle_unregister_device(dev);
        acpi_processor_registered--;
        if (acpi_processor_registered == 0)
            cpuidle_unregister_driver(&acpi_idle_driver);
    }

    pr->flags.power_setup_done = 0;
    return 0;
}