cpufreq.c

来自「优龙2410linux2.6.8内核源代码」· C语言 代码 · 共 108 行

/*
 * linux/arch/arm/mach-imx/cpufreq.c
 *
 * Copyright (c) 2004 Sascha Hauer <[e-mail]>
 *
 * 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 <asm/hardware.h>

static int cur_freq = 200000;

static struct cpufreq_frequency_table imx_cpu_freqs[] = {
	{0x040e200e,	150000},
	{0x00321431,	200000},
	{0,	CPUFREQ_TABLE_END},
};

unsigned int imx_getspeed(void)
{
	return cur_freq;
}

static int imx_target(struct cpufreq_policy *policy,
			 unsigned int target_freq,
			 unsigned int relation)
{
	unsigned int cur = imx_getspeed();
	unsigned int index;

	struct cpufreq_freqs freqs;

	cpufreq_frequency_table_target(policy, imx_cpu_freqs,
                                   target_freq, relation, &index);
	switch(relation){
	case CPUFREQ_RELATION_L:
		break;
	case CPUFREQ_RELATION_H:
		break;
	}

	freqs.old = cur;
	freqs.new = imx_cpu_freqs[index].frequency;
	freqs.cpu = 0;

	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

	cur_freq = imx_cpu_freqs[index].frequency;
	MPCTL0 = imx_cpu_freqs[index].index;
	CSCR |= CSCR_MPLL_RESTART;

	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

	return 0;
}

static int __init imx_cpu_init(struct cpufreq_policy *policy)
{
	if (policy->cpu != 0)
		return -EINVAL;

	cpufreq_frequency_table_cpuinfo(policy,imx_cpu_freqs);

	policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
	policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
	cur_freq = 200000;
	return 0;
}

int imx_verify_speed(struct cpufreq_policy *policy)
{
	if (policy->cpu)
		return -EINVAL;

	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);

	/* make sure that at least one frequency is within the policy */
	cpufreq_frequency_table_verify(policy,imx_cpu_freqs);

	cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq);

	return 0;
}

static struct cpufreq_driver imx_driver = {
	.verify		= imx_verify_speed,
	.target		= imx_target,
	.init		= imx_cpu_init,
	.name		= "imx",
};

static int __init cpufreq_init(void)
{
	cpufreq_gov_userspace_init();
	/* FIXME implement checking for correct cpu */
	return cpufreq_register_driver(&imx_driver);
}

arch_initcall(cpufreq_init);