/*
* Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
*/
/*
* The code contained herein is licensed under the GNU General Public
* License. You may obtain a copy of the GNU General Public License
* Version 2 or later at the following locations:
*
* http://www.opensource.org/licenses/gpl-license.html
* http://www.gnu.org/copyleft/gpl.html
*/
/*
* A driver for the Freescale Semiconductor i.MXC CPUfreq module.
* The CPUFREQ driver is for controling CPU frequency. It allows you to change
* the CPU clock speed on the fly.
*/
#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <mach/hardware.h>
#include <mach/clock.h>
#define CLK32_FREQ 32768
#define NANOSECOND (1000 * 1000 * 1000)
struct cpu_op *(*get_cpu_op)(int *op);
static int cpu_freq_khz_min;
static int cpu_freq_khz_max;
static struct clk *cpu_clk;
static struct cpufreq_frequency_table *imx_freq_table;
static int cpu_op_nr;
static struct cpu_op *cpu_op_tbl;
static int set_cpu_freq(int freq)
{
int ret = 0;
int org_cpu_rate;
org_cpu_rate = clk_get_rate(cpu_clk);
if (org_cpu_rate == freq)
return ret;
ret = clk_set_rate(cpu_clk, freq);
if (ret != 0) {
printk(KERN_DEBUG "cannot set CPU clock rate\n");
return ret;
}
return ret;
}
static int mxc_verify_speed(struct cpufreq_policy *policy)
{
if (policy->cpu != 0)
return -EINVAL;
return cpufreq_frequency_table_verify(policy, imx_freq_table);
}
static unsigned int mxc_get_speed(unsigned int cpu)
{
if (cpu)
return 0;
return clk_get_rate(cpu_clk) / 1000;
}
static int mxc_set_target(struct cpufreq_policy *policy,
unsigned int target_freq, unsigned int relation)
{
struct cpufreq_freqs freqs;
int freq_Hz;
int ret = 0;
unsigned int index;
cpufreq_frequency_table_target(policy, imx_freq_table,
target_freq, relation, &index);
freq_Hz = imx_freq_table[index].frequency * 1000;
freqs.old = clk_get_rate(cpu_clk) / 1000;
freqs.new = freq_Hz / 1000;
freqs.cpu = 0;
freqs.flags = 0;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
ret = set_cpu_freq(freq_Hz);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return ret;
}
static int __init mxc_cpufreq_init(struct cpufreq_policy *policy)
{
int ret;
int i;
printk(KERN_INFO "i.MXC CPU frequency driver\n");
if (policy->cpu != 0)
return -EINVAL;
if (!get_cpu_op)
return -EINVAL;
cpu_clk = clk_get(NULL, "cpu_clk");
if (IS_ERR(cpu_clk)) {
printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);
return PTR_ERR(cpu_clk);
}
cpu_op_tbl = get_cpu_op(&cpu_op_nr);
cpu_freq_khz_min = cpu_op_tbl[0].cpu_rate / 1000;
cpu_freq_khz_max = cpu_op_tbl[0].cpu_rate / 1000;
imx_freq_table = kmalloc(
sizeof(struct cpufreq_frequency_table) * (cpu_op_nr + 1),
GFP_KERNEL);
if (!imx_freq_table) {
ret = -ENOMEM;
goto err1;
}
for (i = 0; i < cpu_op_nr; i++) {
imx_freq_table[i].index = i;
imx_freq_table[i].frequency = cpu_op_tbl[i].cpu_rate / 1000;
if ((cpu_op_tbl[i].cpu_rate / 1000) < cpu_freq_khz_min)
cpu_freq_khz_min = cpu_op_tbl[i].cpu_rate / 1000;
if ((cpu_op_tbl[i].cpu_rate / 1000) > cpu_freq_khz_max)
cpu_freq_khz_max = cpu_op_tbl[i].cpu_rate / 1000;
}
imx_freq_table[i].index = i;
imx_freq_table[i].frequency = CPUFREQ_TABLE_END;
policy->cur = clk_get_rate(cpu_clk) / 1000;
policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
/* Manual states, that PLL stabilizes in two CLK32 periods */
policy->cpuinfo.transition_latency = 2 * NANOSECOND / CLK32_FREQ;
ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);
if (ret < 0) {
printk(KERN_ERR "%s: failed to register i.MXC CPUfreq \
with error code %d\n", __func__, ret);
goto err;
}
cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
return 0;
err:
kfree(imx_freq_table);
err1:
clk_put(cpu_clk);
return ret;
}
static int mxc_cpufreq_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
set_cpu_freq(cpu_freq_khz_max * 1000);
clk_put(cpu_clk);
kfree(imx_freq_table);
return 0;
}
static struct cpufreq_driver mxc_driver = {
.flags = CPUFREQ_STICKY,
.verify = mxc_verify_speed,
.target = mxc_set_target,
.get = mxc_get_speed,
.init = mxc_cpufreq_init,
.exit = mxc_cpufreq_exit,
.name = "imx",
};
static int __devinit mxc_cpufreq_driver_init(void)
{
return cpufreq_register_driver(&mxc_driver);
}
static void mxc_cpufreq_driver_exit(void)
{
cpufreq_unregister_driver(&mxc_driver);
}
module_init(mxc_cpufreq_driver_init);
module_exit(mxc_cpufreq_driver_exit);
MODULE_AUTHOR("Freescale Semiconductor Inc. Yong Shen <yong.shen@linaro.org>");
MODULE_DESCRIPTION("CPUfreq driver for i.MX");
MODULE_LICENSE("GPL");
