acpi-cpufreq.c

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/*
 * acpi-cpufreq.c - ACPI Processor P-States Driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
 *  Copyright (C) 2002 - 2004 Dominik Brodowski <[email protected]>
 *  Copyright (C) 2006       Denis Sadykov <[email protected]>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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/smp.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/compiler.h>
#include <linux/dmi.h>
#include <linux/slab.h>

#include <linux/acpi.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <linux/uaccess.h>

#include <acpi/processor.h>

#include <asm/msr.h>
#include <asm/processor.h>
#include <asm/cpufeature.h>
#include "mperf.h"

MODULE_AUTHOR("Paul Diefenbaugh, Dominik Brodowski");
MODULE_DESCRIPTION("ACPI Processor P-States Driver");
MODULE_LICENSE("GPL");

#define PFX "acpi-cpufreq: "

enum {
    UNDEFINED_CAPABLE = 0,
    SYSTEM_INTEL_MSR_CAPABLE,
    SYSTEM_AMD_MSR_CAPABLE,
    SYSTEM_IO_CAPABLE,
};

#define INTEL_MSR_RANGE     (0xffff)
#define AMD_MSR_RANGE       (0x7)

#define MSR_K7_HWCR_CPB_DIS (1ULL << 25)

struct acpi_cpufreq_data {
    struct acpi_processor_performance *acpi_data;
    struct cpufreq_frequency_table *freq_table;
    unsigned int resume;
    unsigned int cpu_feature;
};

static DEFINE_PER_CPU(struct acpi_cpufreq_data *, acfreq_data);

/* acpi_perf_data is a pointer to percpu data. */
static struct acpi_processor_performance __percpu *acpi_perf_data;

static struct cpufreq_driver acpi_cpufreq_driver;

static unsigned int acpi_pstate_strict;
static bool boost_enabled, boost_supported;
static struct msr __percpu *msrs;

static bool boost_state(unsigned int cpu)
{
    u32 lo, hi;
    u64 msr;

    switch (boot_cpu_data.x86_vendor) {
    case X86_VENDOR_INTEL:
        rdmsr_on_cpu(cpu, MSR_IA32_MISC_ENABLE, &lo, &hi);
        msr = lo | ((u64)hi << 32);
        return !(msr & MSR_IA32_MISC_ENABLE_TURBO_DISABLE);
    case X86_VENDOR_AMD:
        rdmsr_on_cpu(cpu, MSR_K7_HWCR, &lo, &hi);
        msr = lo | ((u64)hi << 32);
        return !(msr & MSR_K7_HWCR_CPB_DIS);
    }
    return false;
}

static void boost_set_msrs(bool enable, const struct cpumask *cpumask)
{
    u32 cpu;
    u32 msr_addr;
    u64 msr_mask;

    switch (boot_cpu_data.x86_vendor) {
    case X86_VENDOR_INTEL:
        msr_addr = MSR_IA32_MISC_ENABLE;
        msr_mask = MSR_IA32_MISC_ENABLE_TURBO_DISABLE;
        break;
    case X86_VENDOR_AMD:
        msr_addr = MSR_K7_HWCR;
        msr_mask = MSR_K7_HWCR_CPB_DIS;
        break;
    default:
        return;
    }

    rdmsr_on_cpus(cpumask, msr_addr, msrs);

    for_each_cpu(cpu, cpumask) {
        struct msr *reg = per_cpu_ptr(msrs, cpu);
        if (enable)
            reg->q &= ~msr_mask;
        else
            reg->q |= msr_mask;
    }

    wrmsr_on_cpus(cpumask, msr_addr, msrs);
}

static ssize_t _store_boost(const char *buf, size_t count)
{
    int ret;
    unsigned long val = 0;

    if (!boost_supported)
        return -EINVAL;

    ret = kstrtoul(buf, 10, &val);
    if (ret || (val > 1))
        return -EINVAL;

    if ((val && boost_enabled) || (!val && !boost_enabled))
        return count;

    get_online_cpus();

    boost_set_msrs(val, cpu_online_mask);

    put_online_cpus();

    boost_enabled = val;
    pr_debug("Core Boosting %sabled.\n", val ? "en" : "dis");

    return count;
}

static ssize_t store_global_boost(struct kobject *kobj, struct attribute *attr,
                  const char *buf, size_t count)
{
    return _store_boost(buf, count);
}

static ssize_t show_global_boost(struct kobject *kobj,
                 struct attribute *attr, char *buf)
{
    return sprintf(buf, "%u\n", boost_enabled);
}

static struct global_attr global_boost = __ATTR(boost, 0644,
                        show_global_boost,
                        store_global_boost);

#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
             size_t count)
{
    return _store_boost(buf, count);
}

static ssize_t show_cpb(struct cpufreq_policy *policy, char *buf)
{
    return sprintf(buf, "%u\n", boost_enabled);
}

static struct freq_attr cpb = __ATTR(cpb, 0644, show_cpb, store_cpb);
#endif

static int check_est_cpu(unsigned int cpuid)
{
    struct cpuinfo_x86 *cpu = &cpu_data(cpuid);

    return cpu_has(cpu, X86_FEATURE_EST);
}

static int check_amd_hwpstate_cpu(unsigned int cpuid)
{
    struct cpuinfo_x86 *cpu = &cpu_data(cpuid);

    return cpu_has(cpu, X86_FEATURE_HW_PSTATE);
}

static unsigned extract_io(u32 value, struct acpi_cpufreq_data *data)
{
    struct acpi_processor_performance *perf;
    int i;

    perf = data->acpi_data;

    for (i = 0; i < perf->state_count; i++) {
        if (value == perf->states[i].status)
            return data->freq_table[i].frequency;
    }
    return 0;
}

static unsigned extract_msr(u32 msr, struct acpi_cpufreq_data *data)
{
    int i;
    struct acpi_processor_performance *perf;

    if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
        msr &= AMD_MSR_RANGE;
    else
        msr &= INTEL_MSR_RANGE;

    perf = data->acpi_data;

    for (i = 0; data->freq_table[i].frequency != CPUFREQ_TABLE_END; i++) {
        if (msr == perf->states[data->freq_table[i].index].status)
            return data->freq_table[i].frequency;
    }
    return data->freq_table[0].frequency;
}

static unsigned extract_freq(u32 val, struct acpi_cpufreq_data *data)
{
    switch (data->cpu_feature) {
    case SYSTEM_INTEL_MSR_CAPABLE:
    case SYSTEM_AMD_MSR_CAPABLE:
        return extract_msr(val, data);
    case SYSTEM_IO_CAPABLE:
        return extract_io(val, data);
    default:
        return 0;
    }
}

struct msr_addr {
    u32 reg;
};

struct io_addr {
    u16 port;
    u8 bit_width;
};

struct drv_cmd {
    unsigned int type;
    const struct cpumask *mask;
    union {
        struct msr_addr msr;
        struct io_addr io;
    } addr;
    u32 val;
};

/* Called via smp_call_function_single(), on the target CPU */
static void do_drv_read(void *_cmd)
{
    struct drv_cmd *cmd = _cmd;
    u32 h;

    switch (cmd->type) {
    case SYSTEM_INTEL_MSR_CAPABLE:
    case SYSTEM_AMD_MSR_CAPABLE:
        rdmsr(cmd->addr.msr.reg, cmd->val, h);
        break;
    case SYSTEM_IO_CAPABLE:
        acpi_os_read_port((acpi_io_address)cmd->addr.io.port,
                &cmd->val,
                (u32)cmd->addr.io.bit_width);
        break;
    default:
        break;
    }
}

/* Called via smp_call_function_many(), on the target CPUs */
static void do_drv_write(void *_cmd)
{
    struct drv_cmd *cmd = _cmd;
    u32 lo, hi;

    switch (cmd->type) {
    case SYSTEM_INTEL_MSR_CAPABLE:
        rdmsr(cmd->addr.msr.reg, lo, hi);
        lo = (lo & ~INTEL_MSR_RANGE) | (cmd->val & INTEL_MSR_RANGE);
        wrmsr(cmd->addr.msr.reg, lo, hi);
        break;
    case SYSTEM_AMD_MSR_CAPABLE:
        wrmsr(cmd->addr.msr.reg, cmd->val, 0);
        break;
    case SYSTEM_IO_CAPABLE:
        acpi_os_write_port((acpi_io_address)cmd->addr.io.port,
                cmd->val,
                (u32)cmd->addr.io.bit_width);
        break;
    default:
        break;
    }
}

static void drv_read(struct drv_cmd *cmd)
{
    int err;
    cmd->val = 0;

    err = smp_call_function_any(cmd->mask, do_drv_read, cmd, 1);
    WARN_ON_ONCE(err);  /* smp_call_function_any() was buggy? */
}

static void drv_write(struct drv_cmd *cmd)
{
    int this_cpu;

    this_cpu = get_cpu();
    if (cpumask_test_cpu(this_cpu, cmd->mask))
        do_drv_write(cmd);
    smp_call_function_many(cmd->mask, do_drv_write, cmd, 1);
    put_cpu();
}

static u32 get_cur_val(const struct cpumask *mask)
{
    struct acpi_processor_performance *perf;
    struct drv_cmd cmd;

    if (unlikely(cpumask_empty(mask)))
        return 0;

    switch (per_cpu(acfreq_data, cpumask_first(mask))->cpu_feature) {
    case SYSTEM_INTEL_MSR_CAPABLE:
        cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
        cmd.addr.msr.reg = MSR_IA32_PERF_STATUS;
        break;
    case SYSTEM_AMD_MSR_CAPABLE:
        cmd.type = SYSTEM_AMD_MSR_CAPABLE;
        cmd.addr.msr.reg = MSR_AMD_PERF_STATUS;
        break;
    case SYSTEM_IO_CAPABLE:
        cmd.type = SYSTEM_IO_CAPABLE;
        perf = per_cpu(acfreq_data, cpumask_first(mask))->acpi_data;
        cmd.addr.io.port = perf->control_register.address;
        cmd.addr.io.bit_width = perf->control_register.bit_width;
        break;
    default:
        return 0;
    }

    cmd.mask = mask;
    drv_read(&cmd);

    pr_debug("get_cur_val = %u\n", cmd.val);

    return cmd.val;
}

static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
{
    struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu);
    unsigned int freq;
    unsigned int cached_freq;

    pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);

    if (unlikely(data == NULL ||
             data->acpi_data == NULL || data->freq_table == NULL)) {
        return 0;
    }

    cached_freq = data->freq_table[data->acpi_data->state].frequency;
    freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
    if (freq != cached_freq) {
        /*
         * The dreaded BIOS frequency change behind our back.
         * Force set the frequency on next target call.
         */
        data->resume = 1;
    }

    pr_debug("cur freq = %u\n", freq);

    return freq;
}

static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq,
                struct acpi_cpufreq_data *data)
{
    unsigned int cur_freq;
    unsigned int i;

    for (i = 0; i < 100; i++) {
        cur_freq = extract_freq(get_cur_val(mask), data);
        if (cur_freq == freq)
            return 1;
        udelay(10);
    }
    return 0;
}

static int acpi_cpufreq_target(struct cpufreq_policy *policy,
                   unsigned int target_freq, unsigned int relation)
{
    struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
    struct acpi_processor_performance *perf;
    struct cpufreq_freqs freqs;
    struct drv_cmd cmd;
    unsigned int next_state = 0; /* Index into freq_table */
    unsigned int next_perf_state = 0; /* Index into perf table */
    unsigned int i;
    int result = 0;

    pr_debug("acpi_cpufreq_target %d (%d)\n", target_freq, policy->cpu);

    if (unlikely(data == NULL ||
         data->acpi_data == NULL || data->freq_table == NULL)) {
        return -ENODEV;
    }

    perf = data->acpi_data;
    result = cpufreq_frequency_table_target(policy,
                        data->freq_table,
                        target_freq,
                        relation, &next_state);
    if (unlikely(result)) {
        result = -ENODEV;
        goto out;
    }

    next_perf_state = data->freq_table[next_state].index;
    if (perf->state == next_perf_state) {
        if (unlikely(data->resume)) {
            pr_debug("Called after resume, resetting to P%d\n",
                next_perf_state);
            data->resume = 0;
        } else {
            pr_debug("Already at target state (P%d)\n",
                next_perf_state);
            goto out;
        }
    }

    switch (data->cpu_feature) {
    case SYSTEM_INTEL_MSR_CAPABLE:
        cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
        cmd.addr.msr.reg = MSR_IA32_PERF_CTL;
        cmd.val = (u32) perf->states[next_perf_state].control;
        break;
    case SYSTEM_AMD_MSR_CAPABLE:
        cmd.type = SYSTEM_AMD_MSR_CAPABLE;
        cmd.addr.msr.reg = MSR_AMD_PERF_CTL;
        cmd.val = (u32) perf->states[next_perf_state].control;
        break;
    case SYSTEM_IO_CAPABLE:
        cmd.type = SYSTEM_IO_CAPABLE;
        cmd.addr.io.port = perf->control_register.address;
        cmd.addr.io.bit_width = perf->control_register.bit_width;
        cmd.val = (u32) perf->states[next_perf_state].control;
        break;
    default:
        result = -ENODEV;
        goto out;
    }

    /* cpufreq holds the hotplug lock, so we are safe from here on */
    if (policy->shared_type != CPUFREQ_SHARED_TYPE_ANY)
        cmd.mask = policy->cpus;
    else
        cmd.mask = cpumask_of(policy->cpu);

    freqs.old = perf->states[perf->state].core_frequency * 1000;
    freqs.new = data->freq_table[next_state].frequency;
    for_each_cpu(i, policy->cpus) {
        freqs.cpu = i;
        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
    }

    drv_write(&cmd);

    if (acpi_pstate_strict) {
        if (!check_freqs(cmd.mask, freqs.new, data)) {
            pr_debug("acpi_cpufreq_target failed (%d)\n",
                policy->cpu);
            result = -EAGAIN;
            goto out;
        }
    }

    for_each_cpu(i, policy->cpus) {
        freqs.cpu = i;
        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
    }
    perf->state = next_perf_state;

out:
    return result;
}

static int acpi_cpufreq_verify(struct cpufreq_policy *policy)
{
    struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);

    pr_debug("acpi_cpufreq_verify\n");

    return cpufreq_frequency_table_verify(policy, data->freq_table);
}

static unsigned long
acpi_cpufreq_guess_freq(struct acpi_cpufreq_data *data, unsigned int cpu)
{
    struct acpi_processor_performance *perf = data->acpi_data;

    if (cpu_khz) {
        /* search the closest match to cpu_khz */
        unsigned int i;
        unsigned long freq;
        unsigned long freqn = perf->states[0].core_frequency * 1000;

        for (i = 0; i < (perf->state_count-1); i++) {
            freq = freqn;
            freqn = perf->states[i+1].core_frequency * 1000;
            if ((2 * cpu_khz) > (freqn + freq)) {
                perf->state = i;
                return freq;
            }
        }
        perf->state = perf->state_count-1;
        return freqn;
    } else {
        /* assume CPU is at P0... */
        perf->state = 0;
        return perf->states[0].core_frequency * 1000;
    }
}

static void free_acpi_perf_data(void)
{
    unsigned int i;

    /* Freeing a NULL pointer is OK, and alloc_percpu zeroes. */
    for_each_possible_cpu(i)
        free_cpumask_var(per_cpu_ptr(acpi_perf_data, i)
                 ->shared_cpu_map);
    free_percpu(acpi_perf_data);
}

static int boost_notify(struct notifier_block *nb, unsigned long action,
              void *hcpu)
{
    unsigned cpu = (long)hcpu;
    const struct cpumask *cpumask;

    cpumask = get_cpu_mask(cpu);

    /*
     * Clear the boost-disable bit on the CPU_DOWN path so that
     * this cpu cannot block the remaining ones from boosting. On
     * the CPU_UP path we simply keep the boost-disable flag in
     * sync with the current global state.
     */

    switch (action) {
    case CPU_UP_PREPARE:
    case CPU_UP_PREPARE_FROZEN:
        boost_set_msrs(boost_enabled, cpumask);
        break;

    case CPU_DOWN_PREPARE:
    case CPU_DOWN_PREPARE_FROZEN:
        boost_set_msrs(1, cpumask);
        break;

    default:
        break;
    }

    return NOTIFY_OK;
}


static struct notifier_block boost_nb = {
    .notifier_call          = boost_notify,
};

/*
 * acpi_cpufreq_early_init - initialize ACPI P-States library
 *
 * Initialize the ACPI P-States library (drivers/acpi/processor_perflib.c)
 * in order to determine correct frequency and voltage pairings. We can
 * do _PDC and _PSD and find out the processor dependency for the
 * actual init that will happen later...
 */
static int __init acpi_cpufreq_early_init(void)
{
    unsigned int i;
    pr_debug("acpi_cpufreq_early_init\n");

    acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
    if (!acpi_perf_data) {
        pr_debug("Memory allocation error for acpi_perf_data.\n");
        return -ENOMEM;
    }
    for_each_possible_cpu(i) {
        if (!zalloc_cpumask_var_node(
            &per_cpu_ptr(acpi_perf_data, i)->shared_cpu_map,
            GFP_KERNEL, cpu_to_node(i))) {

            /* Freeing a NULL pointer is OK: alloc_percpu zeroes. */
            free_acpi_perf_data();
            return -ENOMEM;
        }
    }

    /* Do initialization in ACPI core */
    acpi_processor_preregister_performance(acpi_perf_data);
    return 0;
}

#ifdef CONFIG_SMP
/*
 * Some BIOSes do SW_ANY coordination internally, either set it up in hw
 * or do it in BIOS firmware and won't inform about it to OS. If not
 * detected, this has a side effect of making CPU run at a different speed
 * than OS intended it to run at. Detect it and handle it cleanly.
 */
static int bios_with_sw_any_bug;

static int sw_any_bug_found(const struct dmi_system_id *d)
{
    bios_with_sw_any_bug = 1;
    return 0;
}

static const struct dmi_system_id sw_any_bug_dmi_table[] = {
    {
        .callback = sw_any_bug_found,
        .ident = "Supermicro Server X6DLP",
        .matches = {
            DMI_MATCH(DMI_SYS_VENDOR, "Supermicro"),
            DMI_MATCH(DMI_BIOS_VERSION, "080010"),
            DMI_MATCH(DMI_PRODUCT_NAME, "X6DLP"),
        },
    },
    { }
};

static int acpi_cpufreq_blacklist(struct cpuinfo_x86 *c)
{
    /* Intel Xeon Processor 7100 Series Specification Update
     * http://www.intel.com/Assets/PDF/specupdate/314554.pdf
     * AL30: A Machine Check Exception (MCE) Occurring during an
     * Enhanced Intel SpeedStep Technology Ratio Change May Cause
     * Both Processor Cores to Lock Up. */
    if (c->x86_vendor == X86_VENDOR_INTEL) {
        if ((c->x86 == 15) &&
            (c->x86_model == 6) &&
            (c->x86_mask == 8)) {
            printk(KERN_INFO "acpi-cpufreq: Intel(R) "
                "Xeon(R) 7100 Errata AL30, processors may "
                "lock up on frequency changes: disabling "
                "acpi-cpufreq.\n");
            return -ENODEV;
            }
        }
    return 0;
}
#endif

static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
    unsigned int i;
    unsigned int valid_states = 0;
    unsigned int cpu = policy->cpu;
    struct acpi_cpufreq_data *data;
    unsigned int result = 0;
    struct cpuinfo_x86 *c = &cpu_data(policy->cpu);
    struct acpi_processor_performance *perf;
#ifdef CONFIG_SMP
    static int blacklisted;
#endif

    pr_debug("acpi_cpufreq_cpu_init\n");

#ifdef CONFIG_SMP
    if (blacklisted)
        return blacklisted;
    blacklisted = acpi_cpufreq_blacklist(c);
    if (blacklisted)
        return blacklisted;
#endif

    data = kzalloc(sizeof(struct acpi_cpufreq_data), GFP_KERNEL);
    if (!data)
        return -ENOMEM;

    data->acpi_data = per_cpu_ptr(acpi_perf_data, cpu);
    per_cpu(acfreq_data, cpu) = data;

    if (cpu_has(c, X86_FEATURE_CONSTANT_TSC))
        acpi_cpufreq_driver.flags |= CPUFREQ_CONST_LOOPS;

    result = acpi_processor_register_performance(data->acpi_data, cpu);
    if (result)
        goto err_free;

    perf = data->acpi_data;
    policy->shared_type = perf->shared_type;

    /*
     * Will let policy->cpus know about dependency only when software
     * coordination is required.
     */
    if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL ||
        policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
        cpumask_copy(policy->cpus, perf->shared_cpu_map);
    }
    cpumask_copy(policy->related_cpus, perf->shared_cpu_map);

#ifdef CONFIG_SMP
    dmi_check_system(sw_any_bug_dmi_table);
    if (bios_with_sw_any_bug && cpumask_weight(policy->cpus) == 1) {
        policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
        cpumask_copy(policy->cpus, cpu_core_mask(cpu));
    }

    if (check_amd_hwpstate_cpu(cpu) && !acpi_pstate_strict) {
        cpumask_clear(policy->cpus);
        cpumask_set_cpu(cpu, policy->cpus);
        cpumask_copy(policy->related_cpus, cpu_sibling_mask(cpu));
        policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
        pr_info_once(PFX "overriding BIOS provided _PSD data\n");
    }
#endif

    /* capability check */
    if (perf->state_count <= 1) {
        pr_debug("No P-States\n");
        result = -ENODEV;
        goto err_unreg;
    }

    if (perf->control_register.space_id != perf->status_register.space_id) {
        result = -ENODEV;
        goto err_unreg;
    }

    switch (perf->control_register.space_id) {
    case ACPI_ADR_SPACE_SYSTEM_IO:
        pr_debug("SYSTEM IO addr space\n");
        data->cpu_feature = SYSTEM_IO_CAPABLE;
        break;
    case ACPI_ADR_SPACE_FIXED_HARDWARE:
        pr_debug("HARDWARE addr space\n");
        if (check_est_cpu(cpu)) {
            data->cpu_feature = SYSTEM_INTEL_MSR_CAPABLE;
            break;
        }
        if (check_amd_hwpstate_cpu(cpu)) {
            data->cpu_feature = SYSTEM_AMD_MSR_CAPABLE;
            break;
        }
        result = -ENODEV;
        goto err_unreg;
    default:
        pr_debug("Unknown addr space %d\n",
            (u32) (perf->control_register.space_id));
        result = -ENODEV;
        goto err_unreg;
    }

    data->freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) *
            (perf->state_count+1), GFP_KERNEL);
    if (!data->freq_table) {
        result = -ENOMEM;
        goto err_unreg;
    }

    /* detect transition latency */
    policy->cpuinfo.transition_latency = 0;
    for (i = 0; i < perf->state_count; i++) {
        if ((perf->states[i].transition_latency * 1000) >
            policy->cpuinfo.transition_latency)
            policy->cpuinfo.transition_latency =
                perf->states[i].transition_latency * 1000;
    }

    /* Check for high latency (>20uS) from buggy BIOSes, like on T42 */
    if (perf->control_register.space_id == ACPI_ADR_SPACE_FIXED_HARDWARE &&
        policy->cpuinfo.transition_latency > 20 * 1000) {
        policy->cpuinfo.transition_latency = 20 * 1000;
        printk_once(KERN_INFO
                "P-state transition latency capped at 20 uS\n");
    }

    /* table init */
    for (i = 0; i < perf->state_count; i++) {
        if (i > 0 && perf->states[i].core_frequency >=
            data->freq_table[valid_states-1].frequency / 1000)
            continue;

        data->freq_table[valid_states].index = i;
        data->freq_table[valid_states].frequency =
            perf->states[i].core_frequency * 1000;
        valid_states++;
    }
    data->freq_table[valid_states].frequency = CPUFREQ_TABLE_END;
    perf->state = 0;

    result = cpufreq_frequency_table_cpuinfo(policy, data->freq_table);
    if (result)
        goto err_freqfree;

    if (perf->states[0].core_frequency * 1000 != policy->cpuinfo.max_freq)
        printk(KERN_WARNING FW_WARN "P-state 0 is not max freq\n");

    switch (perf->control_register.space_id) {
    case ACPI_ADR_SPACE_SYSTEM_IO:
        /* Current speed is unknown and not detectable by IO port */
        policy->cur = acpi_cpufreq_guess_freq(data, policy->cpu);
        break;
    case ACPI_ADR_SPACE_FIXED_HARDWARE:
        acpi_cpufreq_driver.get = get_cur_freq_on_cpu;
        policy->cur = get_cur_freq_on_cpu(cpu);
        break;
    default:
        break;
    }

    /* notify BIOS that we exist */
    acpi_processor_notify_smm(THIS_MODULE);

    /* Check for APERF/MPERF support in hardware */
    if (boot_cpu_has(X86_FEATURE_APERFMPERF))
        acpi_cpufreq_driver.getavg = cpufreq_get_measured_perf;

    pr_debug("CPU%u - ACPI performance management activated.\n", cpu);
    for (i = 0; i < perf->state_count; i++)
        pr_debug("     %cP%d: %d MHz, %d mW, %d uS\n",
            (i == perf->state ? '*' : ' '), i,
            (u32) perf->states[i].core_frequency,
            (u32) perf->states[i].power,
            (u32) perf->states[i].transition_latency);

    cpufreq_frequency_table_get_attr(data->freq_table, policy->cpu);

    /*
     * the first call to ->target() should result in us actually
     * writing something to the appropriate registers.
     */
    data->resume = 1;

    return result;

err_freqfree:
    kfree(data->freq_table);
err_unreg:
    acpi_processor_unregister_performance(perf, cpu);
err_free:
    kfree(data);
    per_cpu(acfreq_data, cpu) = NULL;

    return result;
}

static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
    struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);

    pr_debug("acpi_cpufreq_cpu_exit\n");

    if (data) {
        cpufreq_frequency_table_put_attr(policy->cpu);
        per_cpu(acfreq_data, policy->cpu) = NULL;
        acpi_processor_unregister_performance(data->acpi_data,
                              policy->cpu);
        kfree(data->freq_table);
        kfree(data);
    }

    return 0;
}

static int acpi_cpufreq_resume(struct cpufreq_policy *policy)
{
    struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);

    pr_debug("acpi_cpufreq_resume\n");

    data->resume = 1;

    return 0;
}

static struct freq_attr *acpi_cpufreq_attr[] = {
    &cpufreq_freq_attr_scaling_available_freqs,
    NULL,   /* this is a placeholder for cpb, do not remove */
    NULL,
};

static struct cpufreq_driver acpi_cpufreq_driver = {
    .verify     = acpi_cpufreq_verify,
    .target     = acpi_cpufreq_target,
    .bios_limit = acpi_processor_get_bios_limit,
    .init       = acpi_cpufreq_cpu_init,
    .exit       = acpi_cpufreq_cpu_exit,
    .resume     = acpi_cpufreq_resume,
    .name       = "acpi-cpufreq",
    .owner      = THIS_MODULE,
    .attr       = acpi_cpufreq_attr,
};

static void __init acpi_cpufreq_boost_init(void)
{
    if (boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)) {
        msrs = msrs_alloc();

        if (!msrs)
            return;

        boost_supported = true;
        boost_enabled = boost_state(0);

        get_online_cpus();

        /* Force all MSRs to the same value */
        boost_set_msrs(boost_enabled, cpu_online_mask);

        register_cpu_notifier(&boost_nb);

        put_online_cpus();
    } else
        global_boost.attr.mode = 0444;

    /* We create the boost file in any case, though for systems without
     * hardware support it will be read-only and hardwired to return 0.
     */
    if (sysfs_create_file(cpufreq_global_kobject, &(global_boost.attr)))
        pr_warn(PFX "could not register global boost sysfs file\n");
    else
        pr_debug("registered global boost sysfs file\n");
}

static void __exit acpi_cpufreq_boost_exit(void)
{
    sysfs_remove_file(cpufreq_global_kobject, &(global_boost.attr));

    if (msrs) {
        unregister_cpu_notifier(&boost_nb);

        msrs_free(msrs);
        msrs = NULL;
    }
}

static int __init acpi_cpufreq_init(void)
{
    int ret;

    if (acpi_disabled)
        return 0;

    pr_debug("acpi_cpufreq_init\n");

    ret = acpi_cpufreq_early_init();
    if (ret)
        return ret;

#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
    /* this is a sysfs file with a strange name and an even stranger
     * semantic - per CPU instantiation, but system global effect.
     * Lets enable it only on AMD CPUs for compatibility reasons and
     * only if configured. This is considered legacy code, which
     * will probably be removed at some point in the future.
     */
    if (check_amd_hwpstate_cpu(0)) {
        struct freq_attr **iter;

        pr_debug("adding sysfs entry for cpb\n");

        for (iter = acpi_cpufreq_attr; *iter != NULL; iter++)
            ;

        /* make sure there is a terminator behind it */
        if (iter[1] == NULL)
            *iter = &cpb;
    }
#endif

    ret = cpufreq_register_driver(&acpi_cpufreq_driver);
    if (ret)
        free_acpi_perf_data();
    else
        acpi_cpufreq_boost_init();

    return ret;
}

static void __exit acpi_cpufreq_exit(void)
{
    pr_debug("acpi_cpufreq_exit\n");

    acpi_cpufreq_boost_exit();

    cpufreq_unregister_driver(&acpi_cpufreq_driver);

    free_acpi_perf_data();
}

module_param(acpi_pstate_strict, uint, 0644);
MODULE_PARM_DESC(acpi_pstate_strict,
    "value 0 or non-zero. non-zero -> strict ACPI checks are "
    "performed during frequency changes.");

late_initcall(acpi_cpufreq_init);
module_exit(acpi_cpufreq_exit);

MODULE_ALIAS("acpi");