processor_thermal.c

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/*
 * processor_thermal.c - Passive cooling submodule of the ACPI processor driver
 *
 *  Copyright (C) 2001, 2002 Andy Grover <[email protected]>
 *  Copyright (C) 2001, 2002 Paul Diefenbaugh <[email protected]>
 *  Copyright (C) 2004       Dominik Brodowski <[email protected]>
 *  Copyright (C) 2004  Anil S Keshavamurthy <[email protected]>
 *              - Added processor hotplug support
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 *
 *  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/cpufreq.h>

#include <asm/uaccess.h>

#include <acpi/acpi_bus.h>
#include <acpi/processor.h>
#include <acpi/acpi_drivers.h>

#define PREFIX "ACPI: "

#define ACPI_PROCESSOR_CLASS            "processor"
#define _COMPONENT              ACPI_PROCESSOR_COMPONENT
ACPI_MODULE_NAME("processor_thermal");

#ifdef CONFIG_CPU_FREQ

/* If a passive cooling situation is detected, primarily CPUfreq is used, as it
 * offers (in most cases) voltage scaling in addition to frequency scaling, and
 * thus a cubic (instead of linear) reduction of energy. Also, we allow for
 * _any_ cpufreq driver and not only the acpi-cpufreq driver.
 */

#define CPUFREQ_THERMAL_MIN_STEP 0
#define CPUFREQ_THERMAL_MAX_STEP 3

static DEFINE_PER_CPU(unsigned int, cpufreq_thermal_reduction_pctg);
static unsigned int acpi_thermal_cpufreq_is_init = 0;

#define reduction_pctg(cpu) \
    per_cpu(cpufreq_thermal_reduction_pctg, phys_package_first_cpu(cpu))

/*
 * Emulate "per package data" using per cpu data (which should really be
 * provided elsewhere)
 *
 * Note we can lose a CPU on cpu hotunplug, in this case we forget the state
 * temporarily. Fortunately that's not a big issue here (I hope)
 */
static int phys_package_first_cpu(int cpu)
{
    int i;
    int id = topology_physical_package_id(cpu);

    for_each_online_cpu(i)
        if (topology_physical_package_id(i) == id)
            return i;
    return 0;
}

static int cpu_has_cpufreq(unsigned int cpu)
{
    struct cpufreq_policy policy;
    if (!acpi_thermal_cpufreq_is_init || cpufreq_get_policy(&policy, cpu))
        return 0;
    return 1;
}

static int acpi_thermal_cpufreq_notifier(struct notifier_block *nb,
                     unsigned long event, void *data)
{
    struct cpufreq_policy *policy = data;
    unsigned long max_freq = 0;

    if (event != CPUFREQ_ADJUST)
        goto out;

    max_freq = (
        policy->cpuinfo.max_freq *
        (100 - reduction_pctg(policy->cpu) * 20)
    ) / 100;

    cpufreq_verify_within_limits(policy, 0, max_freq);

      out:
    return 0;
}

static struct notifier_block acpi_thermal_cpufreq_notifier_block = {
    .notifier_call = acpi_thermal_cpufreq_notifier,
};

static int cpufreq_get_max_state(unsigned int cpu)
{
    if (!cpu_has_cpufreq(cpu))
        return 0;

    return CPUFREQ_THERMAL_MAX_STEP;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
    if (!cpu_has_cpufreq(cpu))
        return 0;

    return reduction_pctg(cpu);
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
    int i;

    if (!cpu_has_cpufreq(cpu))
        return 0;

    reduction_pctg(cpu) = state;

    /*
     * Update all the CPUs in the same package because they all
     * contribute to the temperature and often share the same
     * frequency.
     */
    for_each_online_cpu(i) {
        if (topology_physical_package_id(i) ==
            topology_physical_package_id(cpu))
            cpufreq_update_policy(i);
    }
    return 0;
}

void acpi_thermal_cpufreq_init(void)
{
    int i;

    i = cpufreq_register_notifier(&acpi_thermal_cpufreq_notifier_block,
                      CPUFREQ_POLICY_NOTIFIER);
    if (!i)
        acpi_thermal_cpufreq_is_init = 1;
}

void acpi_thermal_cpufreq_exit(void)
{
    if (acpi_thermal_cpufreq_is_init)
        cpufreq_unregister_notifier
            (&acpi_thermal_cpufreq_notifier_block,
             CPUFREQ_POLICY_NOTIFIER);

    acpi_thermal_cpufreq_is_init = 0;
}

#else               /* ! CONFIG_CPU_FREQ */
static int cpufreq_get_max_state(unsigned int cpu)
{
    return 0;
}

static int cpufreq_get_cur_state(unsigned int cpu)
{
    return 0;
}

static int cpufreq_set_cur_state(unsigned int cpu, int state)
{
    return 0;
}

#endif

int acpi_processor_get_limit_info(struct acpi_processor *pr)
{

    if (!pr)
        return -EINVAL;

    if (pr->flags.throttling)
        pr->flags.limit = 1;

    return 0;
}

/* thermal coolign device callbacks */
static int acpi_processor_max_state(struct acpi_processor *pr)
{
    int max_state = 0;

    /*
     * There exists four states according to
     * cpufreq_thermal_reduction_ptg. 0, 1, 2, 3
     */
    max_state += cpufreq_get_max_state(pr->id);
    if (pr->flags.throttling)
        max_state += (pr->throttling.state_count -1);

    return max_state;
}
static int
processor_get_max_state(struct thermal_cooling_device *cdev,
            unsigned long *state)
{
    struct acpi_device *device = cdev->devdata;
    struct acpi_processor *pr = acpi_driver_data(device);

    if (!device || !pr)
        return -EINVAL;

    *state = acpi_processor_max_state(pr);
    return 0;
}

static int
processor_get_cur_state(struct thermal_cooling_device *cdev,
            unsigned long *cur_state)
{
    struct acpi_device *device = cdev->devdata;
    struct acpi_processor *pr = acpi_driver_data(device);

    if (!device || !pr)
        return -EINVAL;

    *cur_state = cpufreq_get_cur_state(pr->id);
    if (pr->flags.throttling)
        *cur_state += pr->throttling.state;
    return 0;
}

static int
processor_set_cur_state(struct thermal_cooling_device *cdev,
            unsigned long state)
{
    struct acpi_device *device = cdev->devdata;
    struct acpi_processor *pr = acpi_driver_data(device);
    int result = 0;
    int max_pstate;

    if (!device || !pr)
        return -EINVAL;

    max_pstate = cpufreq_get_max_state(pr->id);

    if (state > acpi_processor_max_state(pr))
        return -EINVAL;

    if (state <= max_pstate) {
        if (pr->flags.throttling && pr->throttling.state)
            result = acpi_processor_set_throttling(pr, 0, false);
        cpufreq_set_cur_state(pr->id, state);
    } else {
        cpufreq_set_cur_state(pr->id, max_pstate);
        result = acpi_processor_set_throttling(pr,
                state - max_pstate, false);
    }
    return result;
}

const struct thermal_cooling_device_ops processor_cooling_ops = {
    .get_max_state = processor_get_max_state,
    .get_cur_state = processor_get_cur_state,
    .set_cur_state = processor_set_cur_state,
};