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/*
* linux/arch/arm/plat-omap/cpu-omap.c
*
* CPU frequency scaling for OMAP
*
* Copyright (C) 2005 Nokia Corporation
* Written by Tony Lindgren <tony@atomide.com>
*
* Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
*
* 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/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <mach/hardware.h>
#include <plat/clock.h>
#include <asm/system.h>
#define VERY_HI_RATE 900000000
static struct cpufreq_frequency_table *freq_table;
#ifdef CONFIG_ARCH_OMAP1
#define MPU_CLK "mpu"
#else
#define MPU_CLK "virt_prcm_set"
#endif
static struct clk *mpu_clk;
/* TODO: Add support for SDRAM timing changes */
static int omap_verify_speed(struct cpufreq_policy *policy)
{
if (freq_table)
return cpufreq_frequency_table_verify(policy, freq_table);
if (policy->cpu)
return -EINVAL;
cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
policy->cpuinfo.max_freq);
policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
policy->cpuinfo.max_freq);
return 0;
}
static unsigned int omap_getspeed(unsigned int cpu)
{
unsigned long rate;
if (cpu)
return 0;
rate = clk_get_rate(mpu_clk) / 1000;
return rate;
}
static int omap_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
struct cpufreq_freqs freqs;
int ret = 0;
/* Ensure desired rate is within allowed range. Some govenors
* (ondemand) will just pass target_freq=0 to get the minimum. */
if (target_freq < policy->min)
target_freq = policy->min;
if (target_freq > policy->max)
target_freq = policy->max;
freqs.old = omap_getspeed(0);
freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
freqs.cpu = 0;
if (freqs.old == freqs.new)
return ret;
cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
#ifdef CONFIG_CPU_FREQ_DEBUG
printk(KERN_DEBUG "cpufreq-omap: transition: %u --> %u\n",
freqs.old, freqs.new);
#endif
ret = clk_set_rate(mpu_clk, freqs.new * 1000);
cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
return ret;
}
static int __init omap_cpu_init(struct cpufreq_policy *policy)
{
int result = 0;
mpu_clk = clk_get(NULL, MPU_CLK);
if (IS_ERR(mpu_clk))
return PTR_ERR(mpu_clk);
if (policy->cpu != 0)
return -EINVAL;
policy->cur = policy->min = policy->max = omap_getspeed(0);
clk_init_cpufreq_table(&freq_table);
if (freq_table) {
result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
if (!result)
cpufreq_frequency_table_get_attr(freq_table,
policy->cpu);
} else {
policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
policy->cpuinfo.max_freq = clk_round_rate(mpu_clk,
VERY_HI_RATE) / 1000;
}
/* FIXME: what's the actual transition time? */
policy->cpuinfo.transition_latency = 300 * 1000;
return 0;
}
static int omap_cpu_exit(struct cpufreq_policy *policy)
{
clk_exit_cpufreq_table(&freq_table);
clk_put(mpu_clk);
return 0;
}
static struct freq_attr *omap_cpufreq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver omap_driver = {
.flags = CPUFREQ_STICKY,
.verify = omap_verify_speed,
.target = omap_target,
.get = omap_getspeed,
.init = omap_cpu_init,
.exit = omap_cpu_exit,
.name = "omap",
.attr = omap_cpufreq_attr,
};
static int __init omap_cpufreq_init(void)
{
return cpufreq_register_driver(&omap_driver);
}
arch_initcall(omap_cpufreq_init);
/*
* if ever we want to remove this, upon cleanup call:
*
* cpufreq_unregister_driver()
* cpufreq_frequency_table_put_attr()
*/
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