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kernel add
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/*
* clock scaling for the UniCore-II
*
* Code specific to PKUnity SoC and UniCore ISA
*
* Maintained by GUAN Xue-tao <gxt@mprc.pku.edu.cn>
* 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/err.h>
#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.
*/
static int ucv2_verify_speed(struct cpufreq_policy *policy)
{
if (policy->cpu)
return -EINVAL;
cpufreq_verify_within_cpu_limits(policy);
return 0;
}
static int ucv2_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct cpufreq_freqs freqs;
int ret;
freqs.old = policy->cur;
freqs.new = target_freq;
cpufreq_freq_transition_begin(policy, &freqs);
ret = clk_set_rate(policy->clk, target_freq * 1000);
cpufreq_freq_transition_end(policy, &freqs, ret);
return ret;
}
static int __init ucv2_cpu_init(struct cpufreq_policy *policy)
{
if (policy->cpu != 0)
return -EINVAL;
policy->min = policy->cpuinfo.min_freq = 250000;
policy->max = policy->cpuinfo.max_freq = 1000000;
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
policy->clk = clk_get(NULL, "MAIN_CLK");
return PTR_ERR_OR_ZERO(policy->clk);
}
static struct cpufreq_driver ucv2_driver = {
.flags = CPUFREQ_STICKY,
.verify = ucv2_verify_speed,
.target = ucv2_target,
.get = cpufreq_generic_get,
.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);
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