acpi-cpufreq.c

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/*
 * arch/ia64/kernel/cpufreq/acpi-cpufreq.c
 * This file provides the ACPI based P-state support. This
 * module works with generic cpufreq infrastructure. Most of
 * the code is based on i386 version
 * (arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c)
 *
 * Copyright (C) 2005 Intel Corp
 *      Venkatesh Pallipadi <[email protected]>
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/pal.h>

#include <linux/acpi.h>
#include <acpi/processor.h>

MODULE_AUTHOR("Venkatesh Pallipadi");
MODULE_DESCRIPTION("ACPI Processor P-States Driver");
MODULE_LICENSE("GPL");


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

static struct cpufreq_acpi_io   *acpi_io_data[NR_CPUS];

static struct cpufreq_driver acpi_cpufreq_driver;


static int
processor_set_pstate (
    u32 value)
{
    s64 retval;

    pr_debug("processor_set_pstate\n");

    retval = ia64_pal_set_pstate((u64)value);

    if (retval) {
        pr_debug("Failed to set freq to 0x%x, with error 0x%lx\n",
                value, retval);
        return -ENODEV;
    }
    return (int)retval;
}


static int
processor_get_pstate (
    u32 *value)
{
    u64 pstate_index = 0;
    s64     retval;

    pr_debug("processor_get_pstate\n");

    retval = ia64_pal_get_pstate(&pstate_index,
                                 PAL_GET_PSTATE_TYPE_INSTANT);
    *value = (u32) pstate_index;

    if (retval)
        pr_debug("Failed to get current freq with "
            "error 0x%lx, idx 0x%x\n", retval, *value);

    return (int)retval;
}


/* To be used only after data->acpi_data is initialized */
static unsigned
extract_clock (
    struct cpufreq_acpi_io *data,
    unsigned value,
    unsigned int cpu)
{
    unsigned long i;

    pr_debug("extract_clock\n");

    for (i = 0; i < data->acpi_data.state_count; i++) {
        if (value == data->acpi_data.states[i].status)
            return data->acpi_data.states[i].core_frequency;
    }
    return data->acpi_data.states[i-1].core_frequency;
}


static unsigned int
processor_get_freq (
    struct cpufreq_acpi_io  *data,
    unsigned int        cpu)
{
    int         ret = 0;
    u32         value = 0;
    cpumask_t       saved_mask;
    unsigned long       clock_freq;

    pr_debug("processor_get_freq\n");

    saved_mask = current->cpus_allowed;
    set_cpus_allowed_ptr(current, cpumask_of(cpu));
    if (smp_processor_id() != cpu)
        goto migrate_end;

    /* processor_get_pstate gets the instantaneous frequency */
    ret = processor_get_pstate(&value);

    if (ret) {
        set_cpus_allowed_ptr(current, &saved_mask);
        printk(KERN_WARNING "get performance failed with error %d\n",
               ret);
        ret = 0;
        goto migrate_end;
    }
    clock_freq = extract_clock(data, value, cpu);
    ret = (clock_freq*1000);

migrate_end:
    set_cpus_allowed_ptr(current, &saved_mask);
    return ret;
}


static int
processor_set_freq (
    struct cpufreq_acpi_io  *data,
    unsigned int        cpu,
    int         state)
{
    int         ret = 0;
    u32         value = 0;
    struct cpufreq_freqs    cpufreq_freqs;
    cpumask_t       saved_mask;
    int         retval;

    pr_debug("processor_set_freq\n");

    saved_mask = current->cpus_allowed;
    set_cpus_allowed_ptr(current, cpumask_of(cpu));
    if (smp_processor_id() != cpu) {
        retval = -EAGAIN;
        goto migrate_end;
    }

    if (state == data->acpi_data.state) {
        if (unlikely(data->resume)) {
            pr_debug("Called after resume, resetting to P%d\n", state);
            data->resume = 0;
        } else {
            pr_debug("Already at target state (P%d)\n", state);
            retval = 0;
            goto migrate_end;
        }
    }

    pr_debug("Transitioning from P%d to P%d\n",
        data->acpi_data.state, state);

    /* cpufreq frequency struct */
    cpufreq_freqs.cpu = cpu;
    cpufreq_freqs.old = data->freq_table[data->acpi_data.state].frequency;
    cpufreq_freqs.new = data->freq_table[state].frequency;

    /* notify cpufreq */
    cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);

    /*
     * First we write the target state's 'control' value to the
     * control_register.
     */

    value = (u32) data->acpi_data.states[state].control;

    pr_debug("Transitioning to state: 0x%08x\n", value);

    ret = processor_set_pstate(value);
    if (ret) {
        unsigned int tmp = cpufreq_freqs.new;
        cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
        cpufreq_freqs.new = cpufreq_freqs.old;
        cpufreq_freqs.old = tmp;
        cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
        cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
        printk(KERN_WARNING "Transition failed with error %d\n", ret);
        retval = -ENODEV;
        goto migrate_end;
    }

    cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);

    data->acpi_data.state = state;

    retval = 0;

migrate_end:
    set_cpus_allowed_ptr(current, &saved_mask);
    return (retval);
}


static unsigned int
acpi_cpufreq_get (
    unsigned int        cpu)
{
    struct cpufreq_acpi_io *data = acpi_io_data[cpu];

    pr_debug("acpi_cpufreq_get\n");

    return processor_get_freq(data, cpu);
}


static int
acpi_cpufreq_target (
    struct cpufreq_policy   *policy,
    unsigned int target_freq,
    unsigned int relation)
{
    struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
    unsigned int next_state = 0;
    unsigned int result = 0;

    pr_debug("acpi_cpufreq_setpolicy\n");

    result = cpufreq_frequency_table_target(policy,
            data->freq_table, target_freq, relation, &next_state);
    if (result)
        return (result);

    result = processor_set_freq(data, policy->cpu, next_state);

    return (result);
}


static int
acpi_cpufreq_verify (
    struct cpufreq_policy   *policy)
{
    unsigned int result = 0;
    struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];

    pr_debug("acpi_cpufreq_verify\n");

    result = cpufreq_frequency_table_verify(policy,
            data->freq_table);

    return (result);
}


static int
acpi_cpufreq_cpu_init (
    struct cpufreq_policy   *policy)
{
    unsigned int        i;
    unsigned int        cpu = policy->cpu;
    struct cpufreq_acpi_io  *data;
    unsigned int        result = 0;

    pr_debug("acpi_cpufreq_cpu_init\n");

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

    acpi_io_data[cpu] = data;

    result = acpi_processor_register_performance(&data->acpi_data, cpu);

    if (result)
        goto err_free;

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

    if ((data->acpi_data.control_register.space_id !=
                    ACPI_ADR_SPACE_FIXED_HARDWARE) ||
        (data->acpi_data.status_register.space_id !=
                    ACPI_ADR_SPACE_FIXED_HARDWARE)) {
        pr_debug("Unsupported address space [%d, %d]\n",
            (u32) (data->acpi_data.control_register.space_id),
            (u32) (data->acpi_data.status_register.space_id));
        result = -ENODEV;
        goto err_unreg;
    }

    /* alloc freq_table */
    data->freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) *
                               (data->acpi_data.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<data->acpi_data.state_count; i++) {
        if ((data->acpi_data.states[i].transition_latency * 1000) >
            policy->cpuinfo.transition_latency) {
            policy->cpuinfo.transition_latency =
                data->acpi_data.states[i].transition_latency * 1000;
        }
    }
    policy->cur = processor_get_freq(data, policy->cpu);

    /* table init */
    for (i = 0; i <= data->acpi_data.state_count; i++)
    {
        data->freq_table[i].index = i;
        if (i < data->acpi_data.state_count) {
            data->freq_table[i].frequency =
                  data->acpi_data.states[i].core_frequency * 1000;
        } else {
            data->freq_table[i].frequency = CPUFREQ_TABLE_END;
        }
    }

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

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

    printk(KERN_INFO "acpi-cpufreq: CPU%u - ACPI performance management "
           "activated.\n", cpu);

    for (i = 0; i < data->acpi_data.state_count; i++)
        pr_debug("     %cP%d: %d MHz, %d mW, %d uS, %d uS, 0x%x 0x%x\n",
            (i == data->acpi_data.state?'*':' '), i,
            (u32) data->acpi_data.states[i].core_frequency,
            (u32) data->acpi_data.states[i].power,
            (u32) data->acpi_data.states[i].transition_latency,
            (u32) data->acpi_data.states[i].bus_master_latency,
            (u32) data->acpi_data.states[i].status,
            (u32) data->acpi_data.states[i].control);

    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(&data->acpi_data, cpu);
 err_free:
    kfree(data);
    acpi_io_data[cpu] = NULL;

    return (result);
}


static int
acpi_cpufreq_cpu_exit (
    struct cpufreq_policy   *policy)
{
    struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];

    pr_debug("acpi_cpufreq_cpu_exit\n");

    if (data) {
        cpufreq_frequency_table_put_attr(policy->cpu);
        acpi_io_data[policy->cpu] = NULL;
        acpi_processor_unregister_performance(&data->acpi_data,
                                              policy->cpu);
        kfree(data);
    }

    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,
    .get        = acpi_cpufreq_get,
    .init       = acpi_cpufreq_cpu_init,
    .exit       = acpi_cpufreq_cpu_exit,
    .name       = "acpi-cpufreq",
    .owner      = THIS_MODULE,
    .attr           = acpi_cpufreq_attr,
};


static int __init
acpi_cpufreq_init (void)
{
    pr_debug("acpi_cpufreq_init\n");

    return cpufreq_register_driver(&acpi_cpufreq_driver);
}


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

    cpufreq_unregister_driver(&acpi_cpufreq_driver);
    return;
}


late_initcall(acpi_cpufreq_init);
module_exit(acpi_cpufreq_exit);