/*
 * Cpufreq driver for the loongson-2 processors
 *
 * The 2E revision of loongson processor not support this feature.
 *
 * Copyright (C) 2006 - 2008 Lemote Inc. & Insititute of Computing Technology
 * Author: Yanhua, yanh@lemote.com
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 */
#define DEBUG
#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/sched.h>	/* set_cpus_allowed() */
#include <linux/delay.h>
#include <linux/platform_device.h>

#include <asm/clock.h>

static struct clk *cpuclk;

/* Minimum CLK support */
enum {
        FREQ_ZERO = 0, FREQ_166M, FREQ_200M, FREQ_250M, FREQ_267M,
        FREQ_RESV
};

struct cpufreq_frequency_table gsc3280_cpufreq_table[] = {
        {FREQ_ZERO, CPUFREQ_ENTRY_INVALID},
        {FREQ_166M, 166500},
        {FREQ_200M, 200000},
        {FREQ_250M, 250000},
        {FREQ_267M, 267000},
        {FREQ_RESV, CPUFREQ_TABLE_END},
};

static int gsc3280_cpu_freq_notifier(struct notifier_block *nb,
                                        unsigned long val, void *data);

static struct notifier_block gsc3280_cpufreq_notifier_block = {
        .notifier_call = gsc3280_cpu_freq_notifier
};

static int gsc3280_cpu_freq_notifier(struct notifier_block *nb,
                                        unsigned long val, void *data)
{
        if (val == CPUFREQ_POSTCHANGE)
                current_cpu_data.udelay_val = loops_per_jiffy;

        return 0;
}

static unsigned int gsc3280_cpufreq_get(unsigned int cpu)
{
	return clk_get_rate(cpuclk)/1000;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int gsc3280_cpufreq_target(struct cpufreq_policy *policy,
				     unsigned int target_freq,
				     unsigned int relation)
{
	unsigned int cpu = policy->cpu;
	unsigned int newstate = 0;
	cpumask_t cpus_allowed;
	struct cpufreq_freqs freqs;
	unsigned int freq;

	if (!cpu_online(cpu))
		return -ENODEV;

	cpus_allowed = current->cpus_allowed;
	set_cpus_allowed_ptr(current, cpumask_of(cpu));

	if (cpufreq_frequency_table_target
	    (policy, &gsc3280_cpufreq_table[0], target_freq, relation,
	     &newstate))
		return -EINVAL;

	freq = gsc3280_cpufreq_table[newstate].frequency;
	if (freq < policy->min || freq > policy->max)
		return -EINVAL;

	freqs.cpu = cpu;
	freqs.old = gsc3280_cpufreq_get(cpu);
	freqs.new = freq;
	freqs.flags = 0;

	if (freqs.new == freqs.old)
		return 0;

	/* notifiers */
	cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

	set_cpus_allowed_ptr(current, &cpus_allowed);

	/* setting the cpu frequency */
	clk_set_rate(cpuclk, freq*1000);

	/* notifiers */
	cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

	pr_debug("cpufreq: set frequency %u kHz\n", freq);

	return 0;
}

static int gsc3280_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
	int i;

	if (!cpu_online(policy->cpu))
		return -ENODEV;

	cpuclk = clk_get(NULL, "cpu");
	if (IS_ERR(cpuclk)) {
		printk(KERN_ERR "cpufreq: couldn't get CPU clk\n");
		return PTR_ERR(cpuclk);
	}

	cpuclk->rate = clk_get_rate(cpuclk);
	if (!cpuclk->rate)
		return -EINVAL;

	policy->cur = cpuclk->rate/1000;

	cpufreq_frequency_table_get_attr(&gsc3280_cpufreq_table[0],
					 policy->cpu);

	return cpufreq_frequency_table_cpuinfo(policy,
					    &gsc3280_cpufreq_table[0]);
}

static int gsc3280_cpufreq_verify(struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy,
					      &gsc3280_cpufreq_table[0]);
}

static int gsc3280_cpufreq_exit(struct cpufreq_policy *policy)
{
	clk_put(cpuclk);
	return 0;
}

static struct freq_attr *gsc3280_table_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	NULL,
};

static struct cpufreq_driver gsc3280_cpufreq_driver = {
	.owner = THIS_MODULE,
	.name = "gsc3280-cpufreq",
	.init = gsc3280_cpufreq_cpu_init,
	.verify = gsc3280_cpufreq_verify,
	.target = gsc3280_cpufreq_target,
	.get = gsc3280_cpufreq_get,
	.exit = gsc3280_cpufreq_exit,
	.attr = gsc3280_table_attr,
};

static int __init cpufreq_init(void)
{
	int ret;

	pr_info("cpufreq: GSC3280 CPU frequency driver.\n");

	cpufreq_register_notifier(&gsc3280_cpufreq_notifier_block,
                                  CPUFREQ_TRANSITION_NOTIFIER);

	ret = cpufreq_register_driver(&gsc3280_cpufreq_driver);

	return ret;
}

static void __exit cpufreq_exit(void)
{
	
	cpufreq_unregister_driver(&gsc3280_cpufreq_driver);
	cpufreq_unregister_notifier(&gsc3280_cpufreq_notifier_block,
                                    CPUFREQ_TRANSITION_NOTIFIER);
}

module_init(cpufreq_init);
module_exit(cpufreq_exit);

MODULE_AUTHOR("Liu Jianhua <liujianhua@china-cpu.com>");
MODULE_DESCRIPTION("CPU frequency scaling driver for gsc3280");
MODULE_LICENSE("GPL");