tracing, perf: Convert the power tracer into an event tracer

[linux-2.6/verdex.git] / arch / x86 / kernel / cpu / cpufreq / acpi-cpufreq.c

/*
 * acpi-cpufreq.c - ACPI Processor P-States Driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
 *  Copyright (C) 2002 - 2004 Dominik Brodowski <linux@brodo.de>
 *  Copyright (C) 2006       Denis Sadykov <denis.m.sadykov@intel.com>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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 <trace/events/power.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>

#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, \
                "acpi-cpufreq", msg)

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

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

#define INTEL_MSR_RANGE         (0xffff)

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 *, drv_data);

static DEFINE_PER_CPU(struct aperfmperf, old_perf);

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

static struct cpufreq_driver acpi_cpufreq_driver;

static unsigned int acpi_pstate_strict;

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

        return cpu_has(cpu, X86_FEATURE_EST);
}

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;

        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:
                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:
                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_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)
{
        cmd->val = 0;

        smp_call_function_single(cpumask_any(cmd->mask), do_drv_read, cmd, 1);
}

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(drv_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_IO_CAPABLE:
                cmd.type = SYSTEM_IO_CAPABLE;
                perf = per_cpu(drv_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);

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

        return cmd.val;
}

/* Called via smp_call_function_single(), on the target CPU */
static void read_measured_perf_ctrs(void *_cur)
{
        struct aperfmperf *am = _cur;

        get_aperfmperf(am);
}

/*
 * Return the measured active (C0) frequency on this CPU since last call
 * to this function.
 * Input: cpu number
 * Return: Average CPU frequency in terms of max frequency (zero on error)
 *
 * We use IA32_MPERF and IA32_APERF MSRs to get the measured performance
 * over a period of time, while CPU is in C0 state.
 * IA32_MPERF counts at the rate of max advertised frequency
 * IA32_APERF counts at the rate of actual CPU frequency
 * Only IA32_APERF/IA32_MPERF ratio is architecturally defined and
 * no meaning should be associated with absolute values of these MSRs.
 */
static unsigned int get_measured_perf(struct cpufreq_policy *policy,
                                      unsigned int cpu)
{
        struct aperfmperf perf;
        unsigned long ratio;
        unsigned int retval;

        if (smp_call_function_single(cpu, read_measured_perf_ctrs, &perf, 1))
                return 0;

        ratio = calc_aperfmperf_ratio(&per_cpu(old_perf, cpu), &perf);
        per_cpu(old_perf, cpu) = perf;

        retval = (policy->cpuinfo.max_freq * ratio) >> APERFMPERF_SHIFT;

        return retval;
}

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

        dprintk("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;
        }

        dprintk("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(drv_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;

        dprintk("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)) {
                        dprintk("Called after resume, resetting to P%d\n",
                                next_perf_state);
                        data->resume = 0;
                } else {
                        dprintk("Already at target state (P%d)\n",
                                next_perf_state);
                        goto out;
                }
        }

        trace_power_frequency(POWER_PSTATE, data->freq_table[next_state].frequency);

        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_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, cmd.mask) {
                freqs.cpu = i;
                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
        }

        drv_write(&cmd);

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

        for_each_cpu(i, cmd.mask) {
                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(drv_data, policy->cpu);

        dprintk("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);
}

/*
 * 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;
        dprintk("acpi_cpufreq_early_init\n");

        acpi_perf_data = alloc_percpu(struct acpi_processor_performance);
        if (!acpi_perf_data) {
                dprintk("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"),
                },
        },
        { }
};
#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;

        dprintk("acpi_cpufreq_cpu_init\n");

        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(drv_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));
        }
#endif

        /* capability check */
        if (perf->state_count <= 1) {
                dprintk("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:
                dprintk("SYSTEM IO addr space\n");
                data->cpu_feature = SYSTEM_IO_CAPABLE;
                break;
        case ACPI_ADR_SPACE_FIXED_HARDWARE:
                dprintk("HARDWARE addr space\n");
                if (!check_est_cpu(cpu)) {
                        result = -ENODEV;
                        goto err_unreg;
                }
                data->cpu_feature = SYSTEM_INTEL_MSR_CAPABLE;
                break;
        default:
                dprintk("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 (cpu_has(c, X86_FEATURE_APERFMPERF))
                acpi_cpufreq_driver.getavg = get_measured_perf;

        dprintk("CPU%u - ACPI performance management activated.\n", cpu);
        for (i = 0; i < perf->state_count; i++)
                dprintk("     %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(drv_data, cpu) = NULL;

        return result;
}

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

        dprintk("acpi_cpufreq_cpu_exit\n");

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

        return 0;
}

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

        dprintk("acpi_cpufreq_resume\n");

        data->resume = 1;

        return 0;
}

static struct freq_attr *acpi_cpufreq_attr[] = {
        &cpufreq_freq_attr_scaling_available_freqs,
        NULL,
};

static struct cpufreq_driver acpi_cpufreq_driver = {
        .verify = acpi_cpufreq_verify,
        .target = acpi_cpufreq_target,
        .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 int __init acpi_cpufreq_init(void)
{
        int ret;

        if (acpi_disabled)
                return 0;

        dprintk("acpi_cpufreq_init\n");

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

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

        return ret;
}

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

        cpufreq_unregister_driver(&acpi_cpufreq_driver);

        free_percpu(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");