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/* linux/arch/arm/plat-s3c64xx/cpufreq.c
*
* Copyright 2009 Wolfson Microelectronics plc
*
* S3C64XX CPUfreq Support
*
* 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/cpufreq.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <mach/cpu.h>
static struct clk *armclk;
static struct cpufreq_frequency_table s3c6410_freq_table[] = {
{ 0, 66000 },
{ 1, 133000 },
{ 2, 222000 },
{ 3, 266000 },
{ 4, 333000 },
{ 5, 400000 },
{ 6, 532000 },
{ 7, 533000 },
{ 8, 667000 },
{ 0, CPUFREQ_TABLE_END },
};
/* Data tables for current CPU and maximum index into it */
static struct cpufreq_frequency_table *s3c64xx_freq_table;
static int s3c64xx_cpufreq_verify_speed(struct cpufreq_policy *policy)
{
if (policy->cpu != 0)
return -EINVAL;
return cpufreq_frequency_table_verify(policy, s3c64xx_freq_table);
}
static unsigned int s3c64xx_cpufreq_get_speed(unsigned int cpu)
{
if (cpu != 0)
return 0;
return clk_get_rate(armclk) / 1000;
}
static int s3c64xx_cpufreq_set_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
int ret;
unsigned int index;
struct cpufreq_freqs freqs;
ret = cpufreq_frequency_table_target(policy, s3c64xx_freq_table,
target_freq, relation, &index);
if (ret != 0)
return ret;
freqs.cpu = 0;
freqs.old = clk_get_rate(armclk) / 1000;
freqs.new = s3c64xx_freq_table[index].frequency;
freqs.flags = 0;
if (freqs.old == freqs.new)
return 0;
pr_debug("cpufreq: Transition %d-%dkHz\n", freqs.old, freqs.new);
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
ret = clk_set_rate(armclk, freqs.new * 1000);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
if (ret < 0) {
pr_err("cpufreq: Failed to set rate %dkHz: %d\n",
freqs.new, ret);
return ret;
}
pr_debug("cpufreq: Set actual frequency %lukHz\n",
clk_get_rate(armclk) / 1000);
return 0;
}
static int __init s3c64xx_cpufreq_driver_init(struct cpufreq_policy *policy)
{
struct cpufreq_frequency_table *freq;;
if (policy->cpu != 0)
return -EINVAL;
if (cpu_is_s3c6410())
s3c64xx_freq_table = s3c6410_freq_table;
if (s3c64xx_freq_table == NULL) {
pr_err("cpufreq: No frequency information for this CPU\n");
return -ENODEV;
}
armclk = clk_get(NULL, "armclk");
if (IS_ERR(armclk)) {
pr_err("cpufreq: Unable to obtain ARMCLK: %ld\n",
PTR_ERR(armclk));
return PTR_ERR(armclk);
}
/* Check for frequencies we can generate */
freq = s3c64xx_freq_table;
while (freq->frequency != CPUFREQ_TABLE_END) {
unsigned long r;
r = clk_round_rate(armclk, freq->frequency * 1000);
r /= 1000;
if (r != freq->frequency)
freq->frequency = CPUFREQ_ENTRY_INVALID;
freq++;
}
policy->cur = clk_get_rate(armclk) / 1000;
policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
return cpufreq_frequency_table_cpuinfo(policy, s3c64xx_freq_table);
}
static struct cpufreq_driver s3c64xx_cpufreq_driver = {
.owner = THIS_MODULE,
.flags = 0,
.verify = s3c64xx_cpufreq_verify_speed,
.target = s3c64xx_cpufreq_set_target,
.get = s3c64xx_cpufreq_get_speed,
.init = s3c64xx_cpufreq_driver_init,
.name = "s3c64xx",
};
static int __init s3c64xx_cpufreq_init(void)
{
return cpufreq_register_driver(&s3c64xx_cpufreq_driver);
}
module_init(s3c64xx_cpufreq_init);
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