Merge branch 'stable' of git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux...

[mirror_ubuntu-zesty-kernel.git] / drivers / 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.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#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>

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_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 {
        unsigned int resume;
        unsigned int cpu_feature;
        unsigned int acpi_perf_cpu;
        cpumask_var_t freqdomain_cpus;
        void (*cpu_freq_write)(struct acpi_pct_register *reg, u32 val);
        u32 (*cpu_freq_read)(struct acpi_pct_register *reg);
};

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

static inline struct acpi_processor_performance *to_perf_data(struct acpi_cpufreq_data *data)
{
        return per_cpu_ptr(acpi_perf_data, data->acpi_perf_cpu);
}

static struct cpufreq_driver acpi_cpufreq_driver;

static unsigned int acpi_pstate_strict;

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 int boost_set_msr(bool enable)
{
        u32 msr_addr;
        u64 msr_mask, val;

        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 -EINVAL;
        }

        rdmsrl(msr_addr, val);

        if (enable)
                val &= ~msr_mask;
        else
                val |= msr_mask;

        wrmsrl(msr_addr, val);
        return 0;
}

static void boost_set_msr_each(void *p_en)
{
        bool enable = (bool) p_en;

        boost_set_msr(enable);
}

static int set_boost(int val)
{
        get_online_cpus();
        on_each_cpu(boost_set_msr_each, (void *)(long)val, 1);
        put_online_cpus();
        pr_debug("Core Boosting %sabled.\n", val ? "en" : "dis");

        return 0;
}

static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
{
        struct acpi_cpufreq_data *data = policy->driver_data;

        if (unlikely(!data))
                return -ENODEV;

        return cpufreq_show_cpus(data->freqdomain_cpus, buf);
}

cpufreq_freq_attr_ro(freqdomain_cpus);

#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
static ssize_t store_cpb(struct cpufreq_policy *policy, const char *buf,
                         size_t count)
{
        int ret;
        unsigned int val = 0;

        if (!acpi_cpufreq_driver.set_boost)
                return -EINVAL;

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

        set_boost(val);

        return count;
}

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

cpufreq_freq_attr_rw(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(struct cpufreq_policy *policy, u32 value)
{
        struct acpi_cpufreq_data *data = policy->driver_data;
        struct acpi_processor_performance *perf;
        int i;

        perf = to_perf_data(data);

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

static unsigned extract_msr(struct cpufreq_policy *policy, u32 msr)
{
        struct acpi_cpufreq_data *data = policy->driver_data;
        struct cpufreq_frequency_table *pos;
        struct acpi_processor_performance *perf;

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

        perf = to_perf_data(data);

        cpufreq_for_each_entry(pos, policy->freq_table)
                if (msr == perf->states[pos->driver_data].status)
                        return pos->frequency;
        return policy->freq_table[0].frequency;
}

static unsigned extract_freq(struct cpufreq_policy *policy, u32 val)
{
        struct acpi_cpufreq_data *data = policy->driver_data;

        switch (data->cpu_feature) {
        case SYSTEM_INTEL_MSR_CAPABLE:
        case SYSTEM_AMD_MSR_CAPABLE:
                return extract_msr(policy, val);
        case SYSTEM_IO_CAPABLE:
                return extract_io(policy, val);
        default:
                return 0;
        }
}

static u32 cpu_freq_read_intel(struct acpi_pct_register *not_used)
{
        u32 val, dummy;

        rdmsr(MSR_IA32_PERF_CTL, val, dummy);
        return val;
}

static void cpu_freq_write_intel(struct acpi_pct_register *not_used, u32 val)
{
        u32 lo, hi;

        rdmsr(MSR_IA32_PERF_CTL, lo, hi);
        lo = (lo & ~INTEL_MSR_RANGE) | (val & INTEL_MSR_RANGE);
        wrmsr(MSR_IA32_PERF_CTL, lo, hi);
}

static u32 cpu_freq_read_amd(struct acpi_pct_register *not_used)
{
        u32 val, dummy;

        rdmsr(MSR_AMD_PERF_CTL, val, dummy);
        return val;
}

static void cpu_freq_write_amd(struct acpi_pct_register *not_used, u32 val)
{
        wrmsr(MSR_AMD_PERF_CTL, val, 0);
}

static u32 cpu_freq_read_io(struct acpi_pct_register *reg)
{
        u32 val;

        acpi_os_read_port(reg->address, &val, reg->bit_width);
        return val;
}

static void cpu_freq_write_io(struct acpi_pct_register *reg, u32 val)
{
        acpi_os_write_port(reg->address, val, reg->bit_width);
}

struct drv_cmd {
        struct acpi_pct_register *reg;
        u32 val;
        union {
                void (*write)(struct acpi_pct_register *reg, u32 val);
                u32 (*read)(struct acpi_pct_register *reg);
        } func;
};

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

        cmd->val = cmd->func.read(cmd->reg);
}

static u32 drv_read(struct acpi_cpufreq_data *data, const struct cpumask *mask)
{
        struct acpi_processor_performance *perf = to_perf_data(data);
        struct drv_cmd cmd = {
                .reg = &perf->control_register,
                .func.read = data->cpu_freq_read,
        };
        int err;

        err = smp_call_function_any(mask, do_drv_read, &cmd, 1);
        WARN_ON_ONCE(err);      /* smp_call_function_any() was buggy? */
        return cmd.val;
}

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

        cmd->func.write(cmd->reg, cmd->val);
}

static void drv_write(struct acpi_cpufreq_data *data,
                      const struct cpumask *mask, u32 val)
{
        struct acpi_processor_performance *perf = to_perf_data(data);
        struct drv_cmd cmd = {
                .reg = &perf->control_register,
                .val = val,
                .func.write = data->cpu_freq_write,
        };
        int this_cpu;

        this_cpu = get_cpu();
        if (cpumask_test_cpu(this_cpu, mask))
                do_drv_write(&cmd);

        smp_call_function_many(mask, do_drv_write, &cmd, 1);
        put_cpu();
}

static u32 get_cur_val(const struct cpumask *mask, struct acpi_cpufreq_data *data)
{
        u32 val;

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

        val = drv_read(data, mask);

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

        return val;
}

static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
{
        struct acpi_cpufreq_data *data;
        struct cpufreq_policy *policy;
        unsigned int freq;
        unsigned int cached_freq;

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

        policy = cpufreq_cpu_get_raw(cpu);
        if (unlikely(!policy))
                return 0;

        data = policy->driver_data;
        if (unlikely(!data || !policy->freq_table))
                return 0;

        cached_freq = policy->freq_table[to_perf_data(data)->state].frequency;
        freq = extract_freq(policy, 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(struct cpufreq_policy *policy,
                                const struct cpumask *mask, unsigned int freq)
{
        struct acpi_cpufreq_data *data = policy->driver_data;
        unsigned int cur_freq;
        unsigned int i;

        for (i = 0; i < 100; i++) {
                cur_freq = extract_freq(policy, 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 index)
{
        struct acpi_cpufreq_data *data = policy->driver_data;
        struct acpi_processor_performance *perf;
        const struct cpumask *mask;
        unsigned int next_perf_state = 0; /* Index into perf table */
        int result = 0;

        if (unlikely(!data)) {
                return -ENODEV;
        }

        perf = to_perf_data(data);
        next_perf_state = policy->freq_table[index].driver_data;
        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);
                        return 0;
                }
        }

        /*
         * The core won't allow CPUs to go away until the governor has been
         * stopped, so we can rely on the stability of policy->cpus.
         */
        mask = policy->shared_type == CPUFREQ_SHARED_TYPE_ANY ?
                cpumask_of(policy->cpu) : policy->cpus;

        drv_write(data, mask, perf->states[next_perf_state].control);

        if (acpi_pstate_strict) {
                if (!check_freqs(policy, mask,
                                 policy->freq_table[index].frequency)) {
                        pr_debug("acpi_cpufreq_target failed (%d)\n",
                                policy->cpu);
                        result = -EAGAIN;
                }
        }

        if (!result)
                perf->state = next_perf_state;

        return result;
}

unsigned int acpi_cpufreq_fast_switch(struct cpufreq_policy *policy,
                                      unsigned int target_freq)
{
        struct acpi_cpufreq_data *data = policy->driver_data;
        struct acpi_processor_performance *perf;
        struct cpufreq_frequency_table *entry;
        unsigned int next_perf_state, next_freq, index;

        /*
         * Find the closest frequency above target_freq.
         */
        if (policy->cached_target_freq == target_freq)
                index = policy->cached_resolved_idx;
        else
                index = cpufreq_table_find_index_dl(policy, target_freq);

        entry = &policy->freq_table[index];
        next_freq = entry->frequency;
        next_perf_state = entry->driver_data;

        perf = to_perf_data(data);
        if (perf->state == next_perf_state) {
                if (unlikely(data->resume))
                        data->resume = 0;
                else
                        return next_freq;
        }

        data->cpu_freq_write(&perf->control_register,
                             perf->states[next_perf_state].control);
        perf->state = next_perf_state;
        return next_freq;
}

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

        perf = to_perf_data(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 cpufreq_boost_online(unsigned int cpu)
{
        /*
         * On the CPU_UP path we simply keep the boost-disable flag
         * in sync with the current global state.
         */
        return boost_set_msr(acpi_cpufreq_driver.boost_enabled);
}

static int cpufreq_boost_down_prep(unsigned int cpu)
{
        /*
         * Clear the boost-disable bit on the CPU_DOWN path so that
         * this cpu cannot block the remaining ones from boosting.
         */
        return boost_set_msr(1);
}

/*
 * 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)) {
                        pr_info("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;
        struct cpufreq_frequency_table *freq_table;
#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(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        if (!zalloc_cpumask_var(&data->freqdomain_cpus, GFP_KERNEL)) {
                result = -ENOMEM;
                goto err_free;
        }

        perf = per_cpu_ptr(acpi_perf_data, cpu);
        data->acpi_perf_cpu = cpu;
        policy->driver_data = data;

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

        result = acpi_processor_register_performance(perf, cpu);
        if (result)
                goto err_free_mask;

        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(data->freqdomain_cpus, perf->shared_cpu_map);

#ifdef CONFIG_SMP
        dmi_check_system(sw_any_bug_dmi_table);
        if (bios_with_sw_any_bug && !policy_is_shared(policy)) {
                policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
                cpumask_copy(policy->cpus, topology_core_cpumask(cpu));
        }

        if (check_amd_hwpstate_cpu(cpu) && !acpi_pstate_strict) {
                cpumask_clear(policy->cpus);
                cpumask_set_cpu(cpu, policy->cpus);
                cpumask_copy(data->freqdomain_cpus,
                             topology_sibling_cpumask(cpu));
                policy->shared_type = CPUFREQ_SHARED_TYPE_HW;
                pr_info_once("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:
                if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
                    boot_cpu_data.x86 == 0xf) {
                        pr_debug("AMD K8 systems must use native drivers.\n");
                        result = -ENODEV;
                        goto err_unreg;
                }
                pr_debug("SYSTEM IO addr space\n");
                data->cpu_feature = SYSTEM_IO_CAPABLE;
                data->cpu_freq_read = cpu_freq_read_io;
                data->cpu_freq_write = cpu_freq_write_io;
                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;
                        data->cpu_freq_read = cpu_freq_read_intel;
                        data->cpu_freq_write = cpu_freq_write_intel;
                        break;
                }
                if (check_amd_hwpstate_cpu(cpu)) {
                        data->cpu_feature = SYSTEM_AMD_MSR_CAPABLE;
                        data->cpu_freq_read = cpu_freq_read_amd;
                        data->cpu_freq_write = cpu_freq_write_amd;
                        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;
        }

        freq_table = kzalloc(sizeof(*freq_table) *
                    (perf->state_count+1), GFP_KERNEL);
        if (!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;
                pr_info_once("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 >=
                    freq_table[valid_states-1].frequency / 1000)
                        continue;

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

        result = cpufreq_table_validate_and_show(policy, freq_table);
        if (result)
                goto err_freqfree;

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

        switch (perf->control_register.space_id) {
        case ACPI_ADR_SPACE_SYSTEM_IO:
                /*
                 * The core will not set policy->cur, because
                 * cpufreq_driver->get is NULL, so we need to set it here.
                 * However, we have to guess it, because the current speed is
                 * unknown and not detectable via IO ports.
                 */
                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;
                break;
        default:
                break;
        }

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

        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);

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

        policy->fast_switch_possible = !acpi_pstate_strict &&
                !(policy_is_shared(policy) && policy->shared_type != CPUFREQ_SHARED_TYPE_ANY);

        return result;

err_freqfree:
        kfree(freq_table);
err_unreg:
        acpi_processor_unregister_performance(cpu);
err_free_mask:
        free_cpumask_var(data->freqdomain_cpus);
err_free:
        kfree(data);
        policy->driver_data = NULL;

        return result;
}

static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
        struct acpi_cpufreq_data *data = policy->driver_data;

        pr_debug("acpi_cpufreq_cpu_exit\n");

        policy->fast_switch_possible = false;
        policy->driver_data = NULL;
        acpi_processor_unregister_performance(data->acpi_perf_cpu);
        free_cpumask_var(data->freqdomain_cpus);
        kfree(policy->freq_table);
        kfree(data);

        return 0;
}

static int acpi_cpufreq_resume(struct cpufreq_policy *policy)
{
        struct acpi_cpufreq_data *data = policy->driver_data;

        pr_debug("acpi_cpufreq_resume\n");

        data->resume = 1;

        return 0;
}

static struct freq_attr *acpi_cpufreq_attr[] = {
        &cpufreq_freq_attr_scaling_available_freqs,
        &freqdomain_cpus,
#ifdef CONFIG_X86_ACPI_CPUFREQ_CPB
        &cpb,
#endif
        NULL,
};

static struct cpufreq_driver acpi_cpufreq_driver = {
        .verify         = cpufreq_generic_frequency_table_verify,
        .target_index   = acpi_cpufreq_target,
        .fast_switch    = acpi_cpufreq_fast_switch,
        .bios_limit     = acpi_processor_get_bios_limit,
        .init           = acpi_cpufreq_cpu_init,
        .exit           = acpi_cpufreq_cpu_exit,
        .resume         = acpi_cpufreq_resume,
        .name           = "acpi-cpufreq",
        .attr           = acpi_cpufreq_attr,
};

static enum cpuhp_state acpi_cpufreq_online;

static void __init acpi_cpufreq_boost_init(void)
{
        int ret;

        if (!(boot_cpu_has(X86_FEATURE_CPB) || boot_cpu_has(X86_FEATURE_IDA)))
                return;

        acpi_cpufreq_driver.set_boost = set_boost;
        acpi_cpufreq_driver.boost_enabled = boost_state(0);

        /*
         * This calls the online callback on all online cpu and forces all
         * MSRs to the same value.
         */
        ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "cpufreq/acpi:online",
                                cpufreq_boost_online, cpufreq_boost_down_prep);
        if (ret < 0) {
                pr_err("acpi_cpufreq: failed to register hotplug callbacks\n");
                return;
        }
        acpi_cpufreq_online = ret;
}

static void acpi_cpufreq_boost_exit(void)
{
        if (acpi_cpufreq_online > 0)
                cpuhp_remove_state_nocalls(acpi_cpufreq_online);
}

static int __init acpi_cpufreq_init(void)
{
        int ret;

        if (acpi_disabled)
                return -ENODEV;

        /* don't keep reloading if cpufreq_driver exists */
        if (cpufreq_get_current_driver())
                return -EEXIST;

        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 **attr;

                pr_debug("CPB unsupported, do not expose it\n");

                for (attr = acpi_cpufreq_attr; *attr; attr++)
                        if (*attr == &cpb) {
                                *attr = NULL;
                                break;
                        }
        }
#endif
        acpi_cpufreq_boost_init();

        ret = cpufreq_register_driver(&acpi_cpufreq_driver);
        if (ret) {
                free_acpi_perf_data();
                acpi_cpufreq_boost_exit();
        }
        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);

static const struct x86_cpu_id acpi_cpufreq_ids[] = {
        X86_FEATURE_MATCH(X86_FEATURE_ACPI),
        X86_FEATURE_MATCH(X86_FEATURE_HW_PSTATE),
        {}
};
MODULE_DEVICE_TABLE(x86cpu, acpi_cpufreq_ids);

static const struct acpi_device_id processor_device_ids[] = {
        {ACPI_PROCESSOR_OBJECT_HID, },
        {ACPI_PROCESSOR_DEVICE_HID, },
        {},
};
MODULE_DEVICE_TABLE(acpi, processor_device_ids);

MODULE_ALIAS("acpi");