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/*
* 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 <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/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(policy, &freqs, CPUFREQ_PRECHANGE);
if (!clk_set_rate(mclk, target_freq * 1000)) {
freqs.old = cur;
freqs.new = target_freq;
}
cpufreq_notify_transition(policy, &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);
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