cpu-ucv2.c

Go to the documentation of this file.

/*
 * linux/arch/unicore32/kernel/cpu-ucv2.c: clock scaling for the UniCore-II
 *
 * Code specific to PKUnity SoC and UniCore ISA
 *
 *  Maintained by GUAN Xue-tao <[email protected]>
 *  Copyright (C) 2001-2010 Guan Xuetao
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>

#include <mach/hardware.h>

static struct cpufreq_driver ucv2_driver;

/* make sure that only the "userspace" governor is run
 * -- anything else wouldn't make sense on this platform, anyway.
 */
int ucv2_verify_speed(struct cpufreq_policy *policy)
{
    if (policy->cpu)
        return -EINVAL;

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

    return 0;
}

static unsigned int ucv2_getspeed(unsigned int cpu)
{
    struct clk *mclk = clk_get(NULL, "MAIN_CLK");

    if (cpu)
        return 0;
    return clk_get_rate(mclk)/1000;
}

static int ucv2_target(struct cpufreq_policy *policy,
             unsigned int target_freq,
             unsigned int relation)
{
    unsigned int cur = ucv2_getspeed(0);
    struct cpufreq_freqs freqs;
    struct clk *mclk = clk_get(NULL, "MAIN_CLK");

    cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

    if (!clk_set_rate(mclk, target_freq * 1000)) {
        freqs.old = cur;
        freqs.new = target_freq;
        freqs.cpu = 0;
    }

    cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

    return 0;
}

static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
{
    if (policy->cpu != 0)
        return -EINVAL;
    policy->cur = ucv2_getspeed(0);
    policy->min = policy->cpuinfo.min_freq = 250000;
    policy->max = policy->cpuinfo.max_freq = 1000000;
    policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
    return 0;
}

static struct cpufreq_driver ucv2_driver = {
    .flags      = CPUFREQ_STICKY,
    .verify     = ucv2_verify_speed,
    .target     = ucv2_target,
    .get        = ucv2_getspeed,
    .init       = ucv2_cpu_init,
    .name       = "UniCore-II",
};

static int __init ucv2_cpufreq_init(void)
{
    return cpufreq_register_driver(&ucv2_driver);
}

arch_initcall(ucv2_cpufreq_init);