loongson2_cpufreq.c

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/*
 * Cpufreq driver for the loongson-2 processors
 *
 * The 2E revision of loongson processor not support this feature.
 *
 * Copyright (C) 2006 - 2008 Lemote Inc. & Insititute of Computing Technology
 * Author: Yanhua, [email protected]
 *
 * 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.
 */
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/sched.h>    /* set_cpus_allowed() */
#include <linux/delay.h>
#include <linux/platform_device.h>

#include <asm/clock.h>

#include <asm/mach-loongson/loongson.h>

static uint nowait;

static struct clk *cpuclk;

static void (*saved_cpu_wait) (void);

static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
                    unsigned long val, void *data);

static struct notifier_block loongson2_cpufreq_notifier_block = {
    .notifier_call = loongson2_cpu_freq_notifier
};

static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
                    unsigned long val, void *data)
{
    if (val == CPUFREQ_POSTCHANGE)
        current_cpu_data.udelay_val = loops_per_jiffy;

    return 0;
}

static unsigned int loongson2_cpufreq_get(unsigned int cpu)
{
    return clk_get_rate(cpuclk);
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
                     unsigned int target_freq,
                     unsigned int relation)
{
    unsigned int cpu = policy->cpu;
    unsigned int newstate = 0;
    cpumask_t cpus_allowed;
    struct cpufreq_freqs freqs;
    unsigned int freq;

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

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

    if (cpufreq_frequency_table_target
        (policy, &loongson2_clockmod_table[0], target_freq, relation,
         &newstate))
        return -EINVAL;

    freq =
        ((cpu_clock_freq / 1000) *
         loongson2_clockmod_table[newstate].index) / 8;
    if (freq < policy->min || freq > policy->max)
        return -EINVAL;

    pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000);

    freqs.cpu = cpu;
    freqs.old = loongson2_cpufreq_get(cpu);
    freqs.new = freq;
    freqs.flags = 0;

    if (freqs.new == freqs.old)
        return 0;

    /* notifiers */
    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

    set_cpus_allowed_ptr(current, &cpus_allowed);

    /* setting the cpu frequency */
    clk_set_rate(cpuclk, freq);

    /* notifiers */
    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    pr_debug("cpufreq: set frequency %u kHz\n", freq);

    return 0;
}

static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
    int i;

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

    cpuclk = clk_get(NULL, "cpu_clk");
    if (IS_ERR(cpuclk)) {
        printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
        return PTR_ERR(cpuclk);
    }

    cpuclk->rate = cpu_clock_freq / 1000;
    if (!cpuclk->rate)
        return -EINVAL;

    /* clock table init */
    for (i = 2;
         (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
         i++)
        loongson2_clockmod_table[i].frequency = (cpuclk->rate * i) / 8;

    policy->cur = loongson2_cpufreq_get(policy->cpu);

    cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0],
                     policy->cpu);

    return cpufreq_frequency_table_cpuinfo(policy,
                        &loongson2_clockmod_table[0]);
}

static int loongson2_cpufreq_verify(struct cpufreq_policy *policy)
{
    return cpufreq_frequency_table_verify(policy,
                          &loongson2_clockmod_table[0]);
}

static int loongson2_cpufreq_exit(struct cpufreq_policy *policy)
{
    clk_put(cpuclk);
    return 0;
}

static struct freq_attr *loongson2_table_attr[] = {
    &cpufreq_freq_attr_scaling_available_freqs,
    NULL,
};

static struct cpufreq_driver loongson2_cpufreq_driver = {
    .owner = THIS_MODULE,
    .name = "loongson2",
    .init = loongson2_cpufreq_cpu_init,
    .verify = loongson2_cpufreq_verify,
    .target = loongson2_cpufreq_target,
    .get = loongson2_cpufreq_get,
    .exit = loongson2_cpufreq_exit,
    .attr = loongson2_table_attr,
};

static struct platform_device_id platform_device_ids[] = {
    {
        .name = "loongson2_cpufreq",
    },
    {}
};

MODULE_DEVICE_TABLE(platform, platform_device_ids);

static struct platform_driver platform_driver = {
    .driver = {
        .name = "loongson2_cpufreq",
        .owner = THIS_MODULE,
    },
    .id_table = platform_device_ids,
};

/*
 * This is the simple version of Loongson-2 wait, Maybe we need do this in
 * interrupt disabled context.
 */

static DEFINE_SPINLOCK(loongson2_wait_lock);

static void loongson2_cpu_wait(void)
{
    unsigned long flags;
    u32 cpu_freq;

    spin_lock_irqsave(&loongson2_wait_lock, flags);
    cpu_freq = LOONGSON_CHIPCFG0;
    LOONGSON_CHIPCFG0 &= ~0x7;      /* Put CPU into wait mode */
    LOONGSON_CHIPCFG0 = cpu_freq;   /* Restore CPU state */
    spin_unlock_irqrestore(&loongson2_wait_lock, flags);
}

static int __init cpufreq_init(void)
{
    int ret;

    /* Register platform stuff */
    ret = platform_driver_register(&platform_driver);
    if (ret)
        return ret;

    pr_info("cpufreq: Loongson-2F CPU frequency driver.\n");

    cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
                  CPUFREQ_TRANSITION_NOTIFIER);

    ret = cpufreq_register_driver(&loongson2_cpufreq_driver);

    if (!ret && !nowait) {
        saved_cpu_wait = cpu_wait;
        cpu_wait = loongson2_cpu_wait;
    }

    return ret;
}

static void __exit cpufreq_exit(void)
{
    if (!nowait && saved_cpu_wait)
        cpu_wait = saved_cpu_wait;
    cpufreq_unregister_driver(&loongson2_cpufreq_driver);
    cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
                    CPUFREQ_TRANSITION_NOTIFIER);

    platform_driver_unregister(&platform_driver);
}

module_init(cpufreq_init);
module_exit(cpufreq_exit);

module_param(nowait, uint, 0644);
MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");

MODULE_AUTHOR("Yanhua <[email protected]>");
MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
MODULE_LICENSE("GPL");