cpufreq.c

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/*
 * arch/sh/kernel/cpufreq.c
 *
 * cpufreq driver for the SuperH processors.
 *
 * Copyright (C) 2002 - 2012 Paul Mundt
 * Copyright (C) 2002 M. R. Brown
 *
 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
 *
 *   Copyright (C) 2004-2007 Atmel Corporation
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#define pr_fmt(fmt) "cpufreq: " fmt

#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/sched.h>    /* set_cpus_allowed() */
#include <linux/clk.h>
#include <linux/percpu.h>
#include <linux/sh_clk.h>

static DEFINE_PER_CPU(struct clk, sh_cpuclk);

static unsigned int sh_cpufreq_get(unsigned int cpu)
{
    return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int sh_cpufreq_target(struct cpufreq_policy *policy,
                 unsigned int target_freq,
                 unsigned int relation)
{
    unsigned int cpu = policy->cpu;
    struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
    cpumask_t cpus_allowed;
    struct cpufreq_freqs freqs;
    struct device *dev;
    long freq;

    if (!cpu_online(cpu))
        return -ENODEV;

    cpus_allowed = current->cpus_allowed;
    set_cpus_allowed_ptr(current, cpumask_of(cpu));

    BUG_ON(smp_processor_id() != cpu);

    dev = get_cpu_device(cpu);

    /* Convert target_freq from kHz to Hz */
    freq = clk_round_rate(cpuclk, target_freq * 1000);

    if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
        return -EINVAL;

    dev_dbg(dev, "requested frequency %u Hz\n", target_freq * 1000);

    freqs.cpu   = cpu;
    freqs.old   = sh_cpufreq_get(cpu);
    freqs.new   = (freq + 500) / 1000;
    freqs.flags = 0;

    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
    set_cpus_allowed_ptr(current, &cpus_allowed);
    clk_set_rate(cpuclk, freq);
    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    dev_dbg(dev, "set frequency %lu Hz\n", freq);

    return 0;
}

static int sh_cpufreq_verify(struct cpufreq_policy *policy)
{
    struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);
    struct cpufreq_frequency_table *freq_table;

    freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
    if (freq_table)
        return cpufreq_frequency_table_verify(policy, freq_table);

    cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                     policy->cpuinfo.max_freq);

    policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
    policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;

    cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                     policy->cpuinfo.max_freq);

    return 0;
}

static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
    unsigned int cpu = policy->cpu;
    struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
    struct cpufreq_frequency_table *freq_table;
    struct device *dev;

    if (!cpu_online(cpu))
        return -ENODEV;

    dev = get_cpu_device(cpu);

    cpuclk = clk_get(dev, "cpu_clk");
    if (IS_ERR(cpuclk)) {
        dev_err(dev, "couldn't get CPU clk\n");
        return PTR_ERR(cpuclk);
    }

    policy->cur = policy->min = policy->max = sh_cpufreq_get(cpu);

    freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
    if (freq_table) {
        int result;

        result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
        if (!result)
            cpufreq_frequency_table_get_attr(freq_table, cpu);
    } else {
        dev_notice(dev, "no frequency table found, falling back "
               "to rate rounding.\n");

        policy->cpuinfo.min_freq =
            (clk_round_rate(cpuclk, 1) + 500) / 1000;
        policy->cpuinfo.max_freq =
            (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
    }

    policy->min = policy->cpuinfo.min_freq;
    policy->max = policy->cpuinfo.max_freq;

    policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

    dev_info(dev, "CPU Frequencies - Minimum %u.%03u MHz, "
           "Maximum %u.%03u MHz.\n",
           policy->min / 1000, policy->min % 1000,
           policy->max / 1000, policy->max % 1000);

    return 0;
}

static int sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
    unsigned int cpu = policy->cpu;
    struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);

    cpufreq_frequency_table_put_attr(cpu);
    clk_put(cpuclk);

    return 0;
}

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

static struct cpufreq_driver sh_cpufreq_driver = {
    .owner      = THIS_MODULE,
    .name       = "sh",
    .get        = sh_cpufreq_get,
    .target     = sh_cpufreq_target,
    .verify     = sh_cpufreq_verify,
    .init       = sh_cpufreq_cpu_init,
    .exit       = sh_cpufreq_cpu_exit,
    .attr       = sh_freq_attr,
};

static int __init sh_cpufreq_module_init(void)
{
    pr_notice("SuperH CPU frequency driver.\n");
    return cpufreq_register_driver(&sh_cpufreq_driver);
}

static void __exit sh_cpufreq_module_exit(void)
{
    cpufreq_unregister_driver(&sh_cpufreq_driver);
}

module_init(sh_cpufreq_module_init);
module_exit(sh_cpufreq_module_exit);

MODULE_AUTHOR("Paul Mundt <[email protected]>");
MODULE_DESCRIPTION("cpufreq driver for SuperH");
MODULE_LICENSE("GPL");