/*
 * Copyright 2015 Sigma Designs
 *
 * 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/module.h>
#include <linux/cpufreq.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sigma Designs");
MODULE_DESCRIPTION("cpufreq driver for Tangox");

static struct cpufreq_frequency_table freq_table[] = {
	{ .driver_data = 1 },
	{ .driver_data = 2 },
	{ .driver_data = 3 },
	{ .driver_data = 5 },
	{ .driver_data = 9 },
	{ .driver_data = 54 },
	{ .frequency = CPUFREQ_TABLE_END }
};

static int tangox_target(struct cpufreq_policy *policy, unsigned int idx)
{
	// TODO: MUST CHECK FOR IDLE BEFORE CALLING clk_set_rate()
	return clk_set_rate(policy->clk, freq_table[idx].frequency * 1000);
}

#define FAST_RAMP_SPEED 15 /* in kHz per nanosecond */

static int tangox_cpu_init(struct cpufreq_policy *policy)
{
	struct cpufreq_frequency_table *p;
	unsigned int freq, transition_latency;

	policy->clk = clk_get_sys("cpu_clk", NULL);
	freq = clk_get_rate(policy->clk) / 1000;
	transition_latency = freq / FAST_RAMP_SPEED;

	for (p = freq_table; p->frequency != CPUFREQ_TABLE_END; ++p) {
		p->frequency = freq / p->driver_data;
	}

	return cpufreq_generic_init(policy, freq_table, transition_latency);
}

static struct cpufreq_driver tangox_cpufreq_driver = {
	.name		= "tangox-cpufreq",
	.init		= tangox_cpu_init,
	.verify		= cpufreq_generic_frequency_table_verify,
	.target_index	= tangox_target,
	.get		= cpufreq_generic_get,
	.exit		= cpufreq_generic_exit,
	.attr		= cpufreq_generic_attr,
};

static int __init tangox_cpufreq_init(void)
{
	return cpufreq_register_driver(&tangox_cpufreq_driver);
}

static void __exit tangox_cpufreq_exit(void)
{
	cpufreq_unregister_driver(&tangox_cpufreq_driver);
}

module_init(tangox_cpufreq_init);
module_exit(tangox_cpufreq_exit);