processor_throttling.c

Go to the documentation of this file.

/*
 * processor_throttling.c - Throttling submodule of the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
 *  Copyright (C) 2004       Dominik Brodowski <[email protected]>
 *  Copyright (C) 2004  Anil S Keshavamurthy <[email protected]>
 *              - Added processor hotplug support
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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/slab.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>

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

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

#define PREFIX "ACPI: "

#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_throttling");

/* ignore_tpc:
 *  0 -> acpi processor driver doesn't ignore _TPC values
 *  1 -> acpi processor driver ignores _TPC values
 */
static int ignore_tpc;
module_param(ignore_tpc, int, 0644);
MODULE_PARM_DESC(ignore_tpc, "Disable broken BIOS _TPC throttling support");

struct throttling_tstate {
    unsigned int cpu;       /* cpu nr */
    int target_state;       /* target T-state */
};

#define THROTTLING_PRECHANGE       (1)
#define THROTTLING_POSTCHANGE      (2)

static int acpi_processor_get_throttling(struct acpi_processor *pr);
int acpi_processor_set_throttling(struct acpi_processor *pr,
                        int state, bool force);

static int acpi_processor_update_tsd_coord(void)
{
    int count, count_target;
    int retval = 0;
    unsigned int i, j;
    cpumask_var_t covered_cpus;
    struct acpi_processor *pr, *match_pr;
    struct acpi_tsd_package *pdomain, *match_pdomain;
    struct acpi_processor_throttling *pthrottling, *match_pthrottling;

    if (!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL))
        return -ENOMEM;

    /*
     * Now that we have _TSD data from all CPUs, lets setup T-state
     * coordination between all CPUs.
     */
    for_each_possible_cpu(i) {
        pr = per_cpu(processors, i);
        if (!pr)
            continue;

        /* Basic validity check for domain info */
        pthrottling = &(pr->throttling);

        /*
         * If tsd package for one cpu is invalid, the coordination
         * among all CPUs is thought as invalid.
         * Maybe it is ugly.
         */
        if (!pthrottling->tsd_valid_flag) {
            retval = -EINVAL;
            break;
        }
    }
    if (retval)
        goto err_ret;

    for_each_possible_cpu(i) {
        pr = per_cpu(processors, i);
        if (!pr)
            continue;

        if (cpumask_test_cpu(i, covered_cpus))
            continue;
        pthrottling = &pr->throttling;

        pdomain = &(pthrottling->domain_info);
        cpumask_set_cpu(i, pthrottling->shared_cpu_map);
        cpumask_set_cpu(i, covered_cpus);
        /*
         * If the number of processor in the TSD domain is 1, it is
         * unnecessary to parse the coordination for this CPU.
         */
        if (pdomain->num_processors <= 1)
            continue;

        /* Validate the Domain info */
        count_target = pdomain->num_processors;
        count = 1;

        for_each_possible_cpu(j) {
            if (i == j)
                continue;

            match_pr = per_cpu(processors, j);
            if (!match_pr)
                continue;

            match_pthrottling = &(match_pr->throttling);
            match_pdomain = &(match_pthrottling->domain_info);
            if (match_pdomain->domain != pdomain->domain)
                continue;

            /* Here i and j are in the same domain.
             * If two TSD packages have the same domain, they
             * should have the same num_porcessors and
             * coordination type. Otherwise it will be regarded
             * as illegal.
             */
            if (match_pdomain->num_processors != count_target) {
                retval = -EINVAL;
                goto err_ret;
            }

            if (pdomain->coord_type != match_pdomain->coord_type) {
                retval = -EINVAL;
                goto err_ret;
            }

            cpumask_set_cpu(j, covered_cpus);
            cpumask_set_cpu(j, pthrottling->shared_cpu_map);
            count++;
        }
        for_each_possible_cpu(j) {
            if (i == j)
                continue;

            match_pr = per_cpu(processors, j);
            if (!match_pr)
                continue;

            match_pthrottling = &(match_pr->throttling);
            match_pdomain = &(match_pthrottling->domain_info);
            if (match_pdomain->domain != pdomain->domain)
                continue;

            /*
             * If some CPUS have the same domain, they
             * will have the same shared_cpu_map.
             */
            cpumask_copy(match_pthrottling->shared_cpu_map,
                     pthrottling->shared_cpu_map);
        }
    }

err_ret:
    free_cpumask_var(covered_cpus);

    for_each_possible_cpu(i) {
        pr = per_cpu(processors, i);
        if (!pr)
            continue;

        /*
         * Assume no coordination on any error parsing domain info.
         * The coordination type will be forced as SW_ALL.
         */
        if (retval) {
            pthrottling = &(pr->throttling);
            cpumask_clear(pthrottling->shared_cpu_map);
            cpumask_set_cpu(i, pthrottling->shared_cpu_map);
            pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
        }
    }

    return retval;
}

/*
 * Update the T-state coordination after the _TSD
 * data for all cpus is obtained.
 */
void acpi_processor_throttling_init(void)
{
    if (acpi_processor_update_tsd_coord())
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
            "Assume no T-state coordination\n"));

    return;
}

static int acpi_processor_throttling_notifier(unsigned long event, void *data)
{
    struct throttling_tstate *p_tstate = data;
    struct acpi_processor *pr;
    unsigned int cpu ;
    int target_state;
    struct acpi_processor_limit *p_limit;
    struct acpi_processor_throttling *p_throttling;

    cpu = p_tstate->cpu;
    pr = per_cpu(processors, cpu);
    if (!pr) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Invalid pr pointer\n"));
        return 0;
    }
    if (!pr->flags.throttling) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Throttling control is "
                "unsupported on CPU %d\n", cpu));
        return 0;
    }
    target_state = p_tstate->target_state;
    p_throttling = &(pr->throttling);
    switch (event) {
    case THROTTLING_PRECHANGE:
        /*
         * Prechange event is used to choose one proper t-state,
         * which meets the limits of thermal, user and _TPC.
         */
        p_limit = &pr->limit;
        if (p_limit->thermal.tx > target_state)
            target_state = p_limit->thermal.tx;
        if (p_limit->user.tx > target_state)
            target_state = p_limit->user.tx;
        if (pr->throttling_platform_limit > target_state)
            target_state = pr->throttling_platform_limit;
        if (target_state >= p_throttling->state_count) {
            printk(KERN_WARNING
                "Exceed the limit of T-state \n");
            target_state = p_throttling->state_count - 1;
        }
        p_tstate->target_state = target_state;
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "PreChange Event:"
                "target T-state of CPU %d is T%d\n",
                cpu, target_state));
        break;
    case THROTTLING_POSTCHANGE:
        /*
         * Postchange event is only used to update the
         * T-state flag of acpi_processor_throttling.
         */
        p_throttling->state = target_state;
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "PostChange Event:"
                "CPU %d is switched to T%d\n",
                cpu, target_state));
        break;
    default:
        printk(KERN_WARNING
            "Unsupported Throttling notifier event\n");
        break;
    }

    return 0;
}

/*
 * _TPC - Throttling Present Capabilities
 */
static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
{
    acpi_status status = 0;
    unsigned long long tpc = 0;

    if (!pr)
        return -EINVAL;

    if (ignore_tpc)
        goto end;

    status = acpi_evaluate_integer(pr->handle, "_TPC", NULL, &tpc);
    if (ACPI_FAILURE(status)) {
        if (status != AE_NOT_FOUND) {
            ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TPC"));
        }
        return -ENODEV;
    }

end:
    pr->throttling_platform_limit = (int)tpc;
    return 0;
}

int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
{
    int result = 0;
    int throttling_limit;
    int current_state;
    struct acpi_processor_limit *limit;
    int target_state;

    if (ignore_tpc)
        return 0;

    result = acpi_processor_get_platform_limit(pr);
    if (result) {
        /* Throttling Limit is unsupported */
        return result;
    }

    throttling_limit = pr->throttling_platform_limit;
    if (throttling_limit >= pr->throttling.state_count) {
        /* Uncorrect Throttling Limit */
        return -EINVAL;
    }

    current_state = pr->throttling.state;
    if (current_state > throttling_limit) {
        /*
         * The current state can meet the requirement of
         * _TPC limit. But it is reasonable that OSPM changes
         * t-states from high to low for better performance.
         * Of course the limit condition of thermal
         * and user should be considered.
         */
        limit = &pr->limit;
        target_state = throttling_limit;
        if (limit->thermal.tx > target_state)
            target_state = limit->thermal.tx;
        if (limit->user.tx > target_state)
            target_state = limit->user.tx;
    } else if (current_state == throttling_limit) {
        /*
         * Unnecessary to change the throttling state
         */
        return 0;
    } else {
        /*
         * If the current state is lower than the limit of _TPC, it
         * will be forced to switch to the throttling state defined
         * by throttling_platfor_limit.
         * Because the previous state meets with the limit condition
         * of thermal and user, it is unnecessary to check it again.
         */
        target_state = throttling_limit;
    }
    return acpi_processor_set_throttling(pr, target_state, false);
}

/*
 * This function is used to reevaluate whether the T-state is valid
 * after one CPU is onlined/offlined.
 * It is noted that it won't reevaluate the following properties for
 * the T-state.
 *  1. Control method.
 *  2. the number of supported T-state
 *  3. TSD domain
 */
void acpi_processor_reevaluate_tstate(struct acpi_processor *pr,
                    unsigned long action)
{
    int result = 0;

    if (action == CPU_DEAD) {
        /* When one CPU is offline, the T-state throttling
         * will be invalidated.
         */
        pr->flags.throttling = 0;
        return;
    }
    /* the following is to recheck whether the T-state is valid for
     * the online CPU
     */
    if (!pr->throttling.state_count) {
        /* If the number of T-state is invalid, it is
         * invalidated.
         */
        pr->flags.throttling = 0;
        return;
    }
    pr->flags.throttling = 1;

    /* Disable throttling (if enabled).  We'll let subsequent
     * policy (e.g.thermal) decide to lower performance if it
     * so chooses, but for now we'll crank up the speed.
     */

    result = acpi_processor_get_throttling(pr);
    if (result)
        goto end;

    if (pr->throttling.state) {
        result = acpi_processor_set_throttling(pr, 0, false);
        if (result)
            goto end;
    }

end:
    if (result)
        pr->flags.throttling = 0;
}
/*
 * _PTC - Processor Throttling Control (and status) register location
 */
static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
{
    int result = 0;
    acpi_status status = 0;
    struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
    union acpi_object *ptc = NULL;
    union acpi_object obj = { 0 };
    struct acpi_processor_throttling *throttling;

    status = acpi_evaluate_object(pr->handle, "_PTC", NULL, &buffer);
    if (ACPI_FAILURE(status)) {
        if (status != AE_NOT_FOUND) {
            ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTC"));
        }
        return -ENODEV;
    }

    ptc = (union acpi_object *)buffer.pointer;
    if (!ptc || (ptc->type != ACPI_TYPE_PACKAGE)
        || (ptc->package.count != 2)) {
        printk(KERN_ERR PREFIX "Invalid _PTC data\n");
        result = -EFAULT;
        goto end;
    }

    /*
     * control_register
     */

    obj = ptc->package.elements[0];

    if ((obj.type != ACPI_TYPE_BUFFER)
        || (obj.buffer.length < sizeof(struct acpi_ptc_register))
        || (obj.buffer.pointer == NULL)) {
        printk(KERN_ERR PREFIX
               "Invalid _PTC data (control_register)\n");
        result = -EFAULT;
        goto end;
    }
    memcpy(&pr->throttling.control_register, obj.buffer.pointer,
           sizeof(struct acpi_ptc_register));

    /*
     * status_register
     */

    obj = ptc->package.elements[1];

    if ((obj.type != ACPI_TYPE_BUFFER)
        || (obj.buffer.length < sizeof(struct acpi_ptc_register))
        || (obj.buffer.pointer == NULL)) {
        printk(KERN_ERR PREFIX "Invalid _PTC data (status_register)\n");
        result = -EFAULT;
        goto end;
    }

    memcpy(&pr->throttling.status_register, obj.buffer.pointer,
           sizeof(struct acpi_ptc_register));

    throttling = &pr->throttling;

    if ((throttling->control_register.bit_width +
        throttling->control_register.bit_offset) > 32) {
        printk(KERN_ERR PREFIX "Invalid _PTC control register\n");
        result = -EFAULT;
        goto end;
    }

    if ((throttling->status_register.bit_width +
        throttling->status_register.bit_offset) > 32) {
        printk(KERN_ERR PREFIX "Invalid _PTC status register\n");
        result = -EFAULT;
        goto end;
    }

      end:
    kfree(buffer.pointer);

    return result;
}

/*
 * _TSS - Throttling Supported States
 */
static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
{
    int result = 0;
    acpi_status status = AE_OK;
    struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
    struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
    struct acpi_buffer state = { 0, NULL };
    union acpi_object *tss = NULL;
    int i;

    status = acpi_evaluate_object(pr->handle, "_TSS", NULL, &buffer);
    if (ACPI_FAILURE(status)) {
        if (status != AE_NOT_FOUND) {
            ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSS"));
        }
        return -ENODEV;
    }

    tss = buffer.pointer;
    if (!tss || (tss->type != ACPI_TYPE_PACKAGE)) {
        printk(KERN_ERR PREFIX "Invalid _TSS data\n");
        result = -EFAULT;
        goto end;
    }

    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
              tss->package.count));

    pr->throttling.state_count = tss->package.count;
    pr->throttling.states_tss =
        kmalloc(sizeof(struct acpi_processor_tx_tss) * tss->package.count,
            GFP_KERNEL);
    if (!pr->throttling.states_tss) {
        result = -ENOMEM;
        goto end;
    }

    for (i = 0; i < pr->throttling.state_count; i++) {

        struct acpi_processor_tx_tss *tx =
            (struct acpi_processor_tx_tss *)&(pr->throttling.
                              states_tss[i]);

        state.length = sizeof(struct acpi_processor_tx_tss);
        state.pointer = tx;

        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Extracting state %d\n", i));

        status = acpi_extract_package(&(tss->package.elements[i]),
                          &format, &state);
        if (ACPI_FAILURE(status)) {
            ACPI_EXCEPTION((AE_INFO, status, "Invalid _TSS data"));
            result = -EFAULT;
            kfree(pr->throttling.states_tss);
            goto end;
        }

        if (!tx->freqpercentage) {
            printk(KERN_ERR PREFIX
                   "Invalid _TSS data: freq is zero\n");
            result = -EFAULT;
            kfree(pr->throttling.states_tss);
            goto end;
        }
    }

      end:
    kfree(buffer.pointer);

    return result;
}

/*
 * _TSD - T-State Dependencies
 */
static int acpi_processor_get_tsd(struct acpi_processor *pr)
{
    int result = 0;
    acpi_status status = AE_OK;
    struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
    struct acpi_buffer format = { sizeof("NNNNN"), "NNNNN" };
    struct acpi_buffer state = { 0, NULL };
    union acpi_object *tsd = NULL;
    struct acpi_tsd_package *pdomain;
    struct acpi_processor_throttling *pthrottling;

    pthrottling = &pr->throttling;
    pthrottling->tsd_valid_flag = 0;

    status = acpi_evaluate_object(pr->handle, "_TSD", NULL, &buffer);
    if (ACPI_FAILURE(status)) {
        if (status != AE_NOT_FOUND) {
            ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSD"));
        }
        return -ENODEV;
    }

    tsd = buffer.pointer;
    if (!tsd || (tsd->type != ACPI_TYPE_PACKAGE)) {
        printk(KERN_ERR PREFIX "Invalid _TSD data\n");
        result = -EFAULT;
        goto end;
    }

    if (tsd->package.count != 1) {
        printk(KERN_ERR PREFIX "Invalid _TSD data\n");
        result = -EFAULT;
        goto end;
    }

    pdomain = &(pr->throttling.domain_info);

    state.length = sizeof(struct acpi_tsd_package);
    state.pointer = pdomain;

    status = acpi_extract_package(&(tsd->package.elements[0]),
                      &format, &state);
    if (ACPI_FAILURE(status)) {
        printk(KERN_ERR PREFIX "Invalid _TSD data\n");
        result = -EFAULT;
        goto end;
    }

    if (pdomain->num_entries != ACPI_TSD_REV0_ENTRIES) {
        printk(KERN_ERR PREFIX "Unknown _TSD:num_entries\n");
        result = -EFAULT;
        goto end;
    }

    if (pdomain->revision != ACPI_TSD_REV0_REVISION) {
        printk(KERN_ERR PREFIX "Unknown _TSD:revision\n");
        result = -EFAULT;
        goto end;
    }

    pthrottling = &pr->throttling;
    pthrottling->tsd_valid_flag = 1;
    pthrottling->shared_type = pdomain->coord_type;
    cpumask_set_cpu(pr->id, pthrottling->shared_cpu_map);
    /*
     * If the coordination type is not defined in ACPI spec,
     * the tsd_valid_flag will be clear and coordination type
     * will be forecd as DOMAIN_COORD_TYPE_SW_ALL.
     */
    if (pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ALL &&
        pdomain->coord_type != DOMAIN_COORD_TYPE_SW_ANY &&
        pdomain->coord_type != DOMAIN_COORD_TYPE_HW_ALL) {
        pthrottling->tsd_valid_flag = 0;
        pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
    }

      end:
    kfree(buffer.pointer);
    return result;
}

/* --------------------------------------------------------------------------
                              Throttling Control
   -------------------------------------------------------------------------- */
static int acpi_processor_get_throttling_fadt(struct acpi_processor *pr)
{
    int state = 0;
    u32 value = 0;
    u32 duty_mask = 0;
    u32 duty_value = 0;

    if (!pr)
        return -EINVAL;

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

    pr->throttling.state = 0;

    duty_mask = pr->throttling.state_count - 1;

    duty_mask <<= pr->throttling.duty_offset;

    local_irq_disable();

    value = inl(pr->throttling.address);

    /*
     * Compute the current throttling state when throttling is enabled
     * (bit 4 is on).
     */
    if (value & 0x10) {
        duty_value = value & duty_mask;
        duty_value >>= pr->throttling.duty_offset;

        if (duty_value)
            state = pr->throttling.state_count - duty_value;
    }

    pr->throttling.state = state;

    local_irq_enable();

    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
              "Throttling state is T%d (%d%% throttling applied)\n",
              state, pr->throttling.states[state].performance));

    return 0;
}

#ifdef CONFIG_X86
static int acpi_throttling_rdmsr(u64 *value)
{
    u64 msr_high, msr_low;
    u64 msr = 0;
    int ret = -1;

    if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
        !this_cpu_has(X86_FEATURE_ACPI)) {
        printk(KERN_ERR PREFIX
            "HARDWARE addr space,NOT supported yet\n");
    } else {
        msr_low = 0;
        msr_high = 0;
        rdmsr_safe(MSR_IA32_THERM_CONTROL,
            (u32 *)&msr_low , (u32 *) &msr_high);
        msr = (msr_high << 32) | msr_low;
        *value = (u64) msr;
        ret = 0;
    }
    return ret;
}

static int acpi_throttling_wrmsr(u64 value)
{
    int ret = -1;
    u64 msr;

    if ((this_cpu_read(cpu_info.x86_vendor) != X86_VENDOR_INTEL) ||
        !this_cpu_has(X86_FEATURE_ACPI)) {
        printk(KERN_ERR PREFIX
            "HARDWARE addr space,NOT supported yet\n");
    } else {
        msr = value;
        wrmsr_safe(MSR_IA32_THERM_CONTROL,
            msr & 0xffffffff, msr >> 32);
        ret = 0;
    }
    return ret;
}
#else
static int acpi_throttling_rdmsr(u64 *value)
{
    printk(KERN_ERR PREFIX
        "HARDWARE addr space,NOT supported yet\n");
    return -1;
}

static int acpi_throttling_wrmsr(u64 value)
{
    printk(KERN_ERR PREFIX
        "HARDWARE addr space,NOT supported yet\n");
    return -1;
}
#endif

static int acpi_read_throttling_status(struct acpi_processor *pr,
                    u64 *value)
{
    u32 bit_width, bit_offset;
    u32 ptc_value;
    u64 ptc_mask;
    struct acpi_processor_throttling *throttling;
    int ret = -1;

    throttling = &pr->throttling;
    switch (throttling->status_register.space_id) {
    case ACPI_ADR_SPACE_SYSTEM_IO:
        bit_width = throttling->status_register.bit_width;
        bit_offset = throttling->status_register.bit_offset;

        acpi_os_read_port((acpi_io_address) throttling->status_register.
                  address, &ptc_value,
                  (u32) (bit_width + bit_offset));
        ptc_mask = (1 << bit_width) - 1;
        *value = (u64) ((ptc_value >> bit_offset) & ptc_mask);
        ret = 0;
        break;
    case ACPI_ADR_SPACE_FIXED_HARDWARE:
        ret = acpi_throttling_rdmsr(value);
        break;
    default:
        printk(KERN_ERR PREFIX "Unknown addr space %d\n",
               (u32) (throttling->status_register.space_id));
    }
    return ret;
}

static int acpi_write_throttling_state(struct acpi_processor *pr,
                u64 value)
{
    u32 bit_width, bit_offset;
    u64 ptc_value;
    u64 ptc_mask;
    struct acpi_processor_throttling *throttling;
    int ret = -1;

    throttling = &pr->throttling;
    switch (throttling->control_register.space_id) {
    case ACPI_ADR_SPACE_SYSTEM_IO:
        bit_width = throttling->control_register.bit_width;
        bit_offset = throttling->control_register.bit_offset;
        ptc_mask = (1 << bit_width) - 1;
        ptc_value = value & ptc_mask;

        acpi_os_write_port((acpi_io_address) throttling->
                    control_register.address,
                    (u32) (ptc_value << bit_offset),
                    (u32) (bit_width + bit_offset));
        ret = 0;
        break;
    case ACPI_ADR_SPACE_FIXED_HARDWARE:
        ret = acpi_throttling_wrmsr(value);
        break;
    default:
        printk(KERN_ERR PREFIX "Unknown addr space %d\n",
               (u32) (throttling->control_register.space_id));
    }
    return ret;
}

static int acpi_get_throttling_state(struct acpi_processor *pr,
                u64 value)
{
    int i;

    for (i = 0; i < pr->throttling.state_count; i++) {
        struct acpi_processor_tx_tss *tx =
            (struct acpi_processor_tx_tss *)&(pr->throttling.
                              states_tss[i]);
        if (tx->control == value)
            return i;
    }
    return -1;
}

static int acpi_get_throttling_value(struct acpi_processor *pr,
            int state, u64 *value)
{
    int ret = -1;

    if (state >= 0 && state <= pr->throttling.state_count) {
        struct acpi_processor_tx_tss *tx =
            (struct acpi_processor_tx_tss *)&(pr->throttling.
                              states_tss[state]);
        *value = tx->control;
        ret = 0;
    }
    return ret;
}

static int acpi_processor_get_throttling_ptc(struct acpi_processor *pr)
{
    int state = 0;
    int ret;
    u64 value;

    if (!pr)
        return -EINVAL;

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

    pr->throttling.state = 0;

    value = 0;
    ret = acpi_read_throttling_status(pr, &value);
    if (ret >= 0) {
        state = acpi_get_throttling_state(pr, value);
        if (state == -1) {
            ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                "Invalid throttling state, reset\n"));
            state = 0;
            ret = acpi_processor_set_throttling(pr, state, true);
            if (ret)
                return ret;
        }
        pr->throttling.state = state;
    }

    return 0;
}

static int acpi_processor_get_throttling(struct acpi_processor *pr)
{
    cpumask_var_t saved_mask;
    int ret;

    if (!pr)
        return -EINVAL;

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

    if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
        return -ENOMEM;

    /*
     * Migrate task to the cpu pointed by pr.
     */
    cpumask_copy(saved_mask, &current->cpus_allowed);
    /* FIXME: use work_on_cpu() */
    if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
        /* Can't migrate to the target pr->id CPU. Exit */
        free_cpumask_var(saved_mask);
        return -ENODEV;
    }
    ret = pr->throttling.acpi_processor_get_throttling(pr);
    /* restore the previous state */
    set_cpus_allowed_ptr(current, saved_mask);
    free_cpumask_var(saved_mask);

    return ret;
}

static int acpi_processor_get_fadt_info(struct acpi_processor *pr)
{
    int i, step;

    if (!pr->throttling.address) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
        return -EINVAL;
    } else if (!pr->throttling.duty_width) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
        return -EINVAL;
    }
    /* TBD: Support duty_cycle values that span bit 4. */
    else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) {
        printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n");
        return -EINVAL;
    }

    pr->throttling.state_count = 1 << acpi_gbl_FADT.duty_width;

    /*
     * Compute state values. Note that throttling displays a linear power
     * performance relationship (at 50% performance the CPU will consume
     * 50% power).  Values are in 1/10th of a percent to preserve accuracy.
     */

    step = (1000 / pr->throttling.state_count);

    for (i = 0; i < pr->throttling.state_count; i++) {
        pr->throttling.states[i].performance = 1000 - step * i;
        pr->throttling.states[i].power = 1000 - step * i;
    }
    return 0;
}

static int acpi_processor_set_throttling_fadt(struct acpi_processor *pr,
                          int state, bool force)
{
    u32 value = 0;
    u32 duty_mask = 0;
    u32 duty_value = 0;

    if (!pr)
        return -EINVAL;

    if ((state < 0) || (state > (pr->throttling.state_count - 1)))
        return -EINVAL;

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

    if (!force && (state == pr->throttling.state))
        return 0;

    if (state < pr->throttling_platform_limit)
        return -EPERM;
    /*
     * Calculate the duty_value and duty_mask.
     */
    if (state) {
        duty_value = pr->throttling.state_count - state;

        duty_value <<= pr->throttling.duty_offset;

        /* Used to clear all duty_value bits */
        duty_mask = pr->throttling.state_count - 1;

        duty_mask <<= acpi_gbl_FADT.duty_offset;
        duty_mask = ~duty_mask;
    }

    local_irq_disable();

    /*
     * Disable throttling by writing a 0 to bit 4.  Note that we must
     * turn it off before you can change the duty_value.
     */
    value = inl(pr->throttling.address);
    if (value & 0x10) {
        value &= 0xFFFFFFEF;
        outl(value, pr->throttling.address);
    }

    /*
     * Write the new duty_value and then enable throttling.  Note
     * that a state value of 0 leaves throttling disabled.
     */
    if (state) {
        value &= duty_mask;
        value |= duty_value;
        outl(value, pr->throttling.address);

        value |= 0x00000010;
        outl(value, pr->throttling.address);
    }

    pr->throttling.state = state;

    local_irq_enable();

    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
              "Throttling state set to T%d (%d%%)\n", state,
              (pr->throttling.states[state].performance ? pr->
               throttling.states[state].performance / 10 : 0)));

    return 0;
}

static int acpi_processor_set_throttling_ptc(struct acpi_processor *pr,
                         int state, bool force)
{
    int ret;
    u64 value;

    if (!pr)
        return -EINVAL;

    if ((state < 0) || (state > (pr->throttling.state_count - 1)))
        return -EINVAL;

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

    if (!force && (state == pr->throttling.state))
        return 0;

    if (state < pr->throttling_platform_limit)
        return -EPERM;

    value = 0;
    ret = acpi_get_throttling_value(pr, state, &value);
    if (ret >= 0) {
        acpi_write_throttling_state(pr, value);
        pr->throttling.state = state;
    }

    return 0;
}

int acpi_processor_set_throttling(struct acpi_processor *pr,
                        int state, bool force)
{
    cpumask_var_t saved_mask;
    int ret = 0;
    unsigned int i;
    struct acpi_processor *match_pr;
    struct acpi_processor_throttling *p_throttling;
    struct throttling_tstate t_state;
    cpumask_var_t online_throttling_cpus;

    if (!pr)
        return -EINVAL;

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

    if ((state < 0) || (state > (pr->throttling.state_count - 1)))
        return -EINVAL;

    if (!alloc_cpumask_var(&saved_mask, GFP_KERNEL))
        return -ENOMEM;

    if (!alloc_cpumask_var(&online_throttling_cpus, GFP_KERNEL)) {
        free_cpumask_var(saved_mask);
        return -ENOMEM;
    }

    if (cpu_is_offline(pr->id)) {
        /*
         * the cpu pointed by pr->id is offline. Unnecessary to change
         * the throttling state any more.
         */
        return -ENODEV;
    }

    cpumask_copy(saved_mask, &current->cpus_allowed);
    t_state.target_state = state;
    p_throttling = &(pr->throttling);
    cpumask_and(online_throttling_cpus, cpu_online_mask,
            p_throttling->shared_cpu_map);
    /*
     * The throttling notifier will be called for every
     * affected cpu in order to get one proper T-state.
     * The notifier event is THROTTLING_PRECHANGE.
     */
    for_each_cpu(i, online_throttling_cpus) {
        t_state.cpu = i;
        acpi_processor_throttling_notifier(THROTTLING_PRECHANGE,
                            &t_state);
    }
    /*
     * The function of acpi_processor_set_throttling will be called
     * to switch T-state. If the coordination type is SW_ALL or HW_ALL,
     * it is necessary to call it for every affected cpu. Otherwise
     * it can be called only for the cpu pointed by pr.
     */
    if (p_throttling->shared_type == DOMAIN_COORD_TYPE_SW_ANY) {
        /* FIXME: use work_on_cpu() */
        if (set_cpus_allowed_ptr(current, cpumask_of(pr->id))) {
            /* Can't migrate to the pr->id CPU. Exit */
            ret = -ENODEV;
            goto exit;
        }
        ret = p_throttling->acpi_processor_set_throttling(pr,
                        t_state.target_state, force);
    } else {
        /*
         * When the T-state coordination is SW_ALL or HW_ALL,
         * it is necessary to set T-state for every affected
         * cpus.
         */
        for_each_cpu(i, online_throttling_cpus) {
            match_pr = per_cpu(processors, i);
            /*
             * If the pointer is invalid, we will report the
             * error message and continue.
             */
            if (!match_pr) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                    "Invalid Pointer for CPU %d\n", i));
                continue;
            }
            /*
             * If the throttling control is unsupported on CPU i,
             * we will report the error message and continue.
             */
            if (!match_pr->flags.throttling) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                    "Throttling Control is unsupported "
                    "on CPU %d\n", i));
                continue;
            }
            t_state.cpu = i;
            /* FIXME: use work_on_cpu() */
            if (set_cpus_allowed_ptr(current, cpumask_of(i)))
                continue;
            ret = match_pr->throttling.
                acpi_processor_set_throttling(
                match_pr, t_state.target_state, force);
        }
    }
    /*
     * After the set_throttling is called, the
     * throttling notifier is called for every
     * affected cpu to update the T-states.
     * The notifier event is THROTTLING_POSTCHANGE
     */
    for_each_cpu(i, online_throttling_cpus) {
        t_state.cpu = i;
        acpi_processor_throttling_notifier(THROTTLING_POSTCHANGE,
                            &t_state);
    }
    /* restore the previous state */
    /* FIXME: use work_on_cpu() */
    set_cpus_allowed_ptr(current, saved_mask);
exit:
    free_cpumask_var(online_throttling_cpus);
    free_cpumask_var(saved_mask);
    return ret;
}

int acpi_processor_get_throttling_info(struct acpi_processor *pr)
{
    int result = 0;
    struct acpi_processor_throttling *pthrottling;

    ACPI_DEBUG_PRINT((ACPI_DB_INFO,
              "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
              pr->throttling.address,
              pr->throttling.duty_offset,
              pr->throttling.duty_width));

    /*
     * Evaluate _PTC, _TSS and _TPC
     * They must all be present or none of them can be used.
     */
    if (acpi_processor_get_throttling_control(pr) ||
        acpi_processor_get_throttling_states(pr) ||
        acpi_processor_get_platform_limit(pr))
    {
        pr->throttling.acpi_processor_get_throttling =
            &acpi_processor_get_throttling_fadt;
        pr->throttling.acpi_processor_set_throttling =
            &acpi_processor_set_throttling_fadt;
        if (acpi_processor_get_fadt_info(pr))
            return 0;
    } else {
        pr->throttling.acpi_processor_get_throttling =
            &acpi_processor_get_throttling_ptc;
        pr->throttling.acpi_processor_set_throttling =
            &acpi_processor_set_throttling_ptc;
    }

    /*
     * If TSD package for one CPU can't be parsed successfully, it means
     * that this CPU will have no coordination with other CPUs.
     */
    if (acpi_processor_get_tsd(pr)) {
        pthrottling = &pr->throttling;
        pthrottling->tsd_valid_flag = 0;
        cpumask_set_cpu(pr->id, pthrottling->shared_cpu_map);
        pthrottling->shared_type = DOMAIN_COORD_TYPE_SW_ALL;
    }

    /*
     * PIIX4 Errata: We don't support throttling on the original PIIX4.
     * This shouldn't be an issue as few (if any) mobile systems ever
     * used this part.
     */
    if (errata.piix4.throttle) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Throttling not supported on PIIX4 A- or B-step\n"));
        return 0;
    }

    ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
              pr->throttling.state_count));

    pr->flags.throttling = 1;

    /*
     * Disable throttling (if enabled).  We'll let subsequent policy (e.g.
     * thermal) decide to lower performance if it so chooses, but for now
     * we'll crank up the speed.
     */

    result = acpi_processor_get_throttling(pr);
    if (result)
        goto end;

    if (pr->throttling.state) {
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                  "Disabling throttling (was T%d)\n",
                  pr->throttling.state));
        result = acpi_processor_set_throttling(pr, 0, false);
        if (result)
            goto end;
    }

      end:
    if (result)
        pr->flags.throttling = 0;

    return result;
}