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/*
* linux/arch/arm/mach-mx2/cpufreq.c
*
* Copyright (C) 2009 Sascha Hauer, Pengutronix
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <mach/hardware.h>
static struct cpufreq_frequency_table mx27_freq_table[4 + 1];
static struct clk *clk_cpu, *clk_mpll;
static unsigned long mpll_rate;
static int mx27_verify_policy(struct cpufreq_policy *policy)
{ return cpufreq_frequency_table_verify(policy, mx27_freq_table);
}
static unsigned int mx27_cpufreq_get(unsigned int cpu)
{
return clk_get_rate(clk_cpu) / 1000;
}
static unsigned char cpu_dividers[] = {2, 3, 6};
static int mx27_set_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct cpufreq_freqs freqs;
unsigned int idx;
/* Lookup the next frequency */
if (cpufreq_frequency_table_target(policy, mx27_freq_table,
target_freq, relation, &idx))
return -EINVAL;
freqs.old = policy->cur;
freqs.new = mx27_freq_table[idx].frequency;
freqs.cpu = policy->cpu;
/*
* Tell everyone what we're about to do...
* you should add a notify client with any platform specific
* Vcc changing capability
*/
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
clk_set_rate(clk_cpu, mpll_rate * 2 / cpu_dividers[idx]);
/*
* Tell everyone what we've just done...
* you should add a notify client with any platform specific
* SDRAM refresh timer adjustments
*/
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return 0;
}
static __init int mx27_cpufreq_init(struct cpufreq_policy *policy)
{
int ret, i;
clk_cpu = clk_get(NULL, "cpu");
if (IS_ERR(clk_cpu))
return PTR_ERR(clk_cpu);
clk_mpll = clk_get(NULL, "mpll");
if (IS_ERR(clk_mpll)) {
ret = PTR_ERR(clk_mpll);
goto out;
}
mpll_rate = clk_get_rate(clk_mpll);
/* set default policy and cpuinfo */
policy->cpuinfo.transition_latency = 10;
policy->cur = clk_get_rate(clk_cpu) / 1000;
policy->min = mpll_rate / 3;
policy->max = mpll_rate;
for (i = 0; i < ARRAY_SIZE(cpu_dividers); i++) {
mx27_freq_table[i].index = i;
mx27_freq_table[i].frequency = mpll_rate * 2 / cpu_dividers[i] / 1000;
}
mx27_freq_table[i].frequency = CPUFREQ_TABLE_END;
cpufreq_frequency_table_cpuinfo(policy, mx27_freq_table);
printk(KERN_INFO "i.MX27 CPU frequency change support initialized %d %d\n",
policy->min, policy->max);
return 0;
out:
clk_put(clk_cpu);
return ret;
}
static struct cpufreq_driver mx27_cpufreq_driver = {
.verify = mx27_verify_policy,
.target = mx27_set_target,
.init = mx27_cpufreq_init,
.get = mx27_cpufreq_get,
.name = "i.MX27",
};
static int __init mx27_cpu_init(void)
{
if (!cpu_is_mx27())
return -ENODEV;
return cpufreq_register_driver(&mx27_cpufreq_driver);
}
static void __exit mx27_cpu_exit(void)
{
cpufreq_unregister_driver(&mx27_cpufreq_driver);
}
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
MODULE_DESCRIPTION("CPU frequency changing driver for the i.MX27");
MODULE_LICENSE("GPL");
module_init(mx27_cpu_init);
module_exit(mx27_cpu_exit);
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