[CPUFREQ] Move x86 drivers to drivers/cpufreq/

Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 773 insertions, 0 deletions

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
new file mode 100644
index 000000000000..4e04e1274388
--- /dev/null
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -0,0 +1,773 @@
+/*
+ * 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 <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");
+
+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 *, 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 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)
+{
+        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_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_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);
+}
+
+/*
+ * 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));
+        }
+#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)) {
+                        result = -ENODEV;
+                        goto err_unreg;
+                }
+                data->cpu_feature = SYSTEM_INTEL_MSR_CAPABLE;
+                break;
+        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 (cpu_has(c, 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,
+};
+
+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 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;
+
+        ret = cpufreq_register_driver(&acpi_cpufreq_driver);
+        if (ret)
+                free_acpi_perf_data();
+
+        return ret;
+}
+
+static void __exit acpi_cpufreq_exit(void)
+{
+        pr_debug("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");