/*
 * Copyright (C) 2011 Freescale Semiconductor, Inc.
 */

/*
 * 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
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/cpufreq.h>
#include <linux/clk.h>
#include <linux/regulator/consumer.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/of.h>

static u32 *cpu_freqs; /* Hz */
static u32 *cpu_volts; /* uV */
static u32 trans_latency; /* ns */
static int cpu_op_nr;
static unsigned int cur_index;

static struct clk *cpu_clk;
static struct regulator *cpu_reg;
static struct cpufreq_frequency_table *freq_table;

static int set_cpu_freq(unsigned long freq, int index, int higher)
{
	int ret = 0;

	if (higher && cpu_reg) {
		ret = regulator_set_voltage(cpu_reg,
				cpu_volts[index * 2], cpu_volts[index * 2 + 1]);
		if (ret) {
			pr_err("set cpu voltage failed!\n");
			return ret;
		}
	}

	ret = clk_set_rate(cpu_clk, freq);
	if (ret) {
		if (cpu_reg)
			regulator_set_voltage(cpu_reg, cpu_volts[cur_index * 2],
						cpu_volts[cur_index * 2 + 1]);
		pr_err("cannot set CPU clock rate\n");
		return ret;
	}

	if (!higher && cpu_reg) {
		ret = regulator_set_voltage(cpu_reg,
				cpu_volts[index * 2], cpu_volts[index * 2 + 1]);
		if (ret)
			pr_warn("set cpu voltage failed, might run on"
				" higher voltage!\n");
		ret = 0;
	}

	return ret;
}

static int clk_reg_verify_speed(struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy, freq_table);
}

static unsigned int clk_reg_get_speed(unsigned int cpu)
{
	return clk_get_rate(cpu_clk) / 1000;
}

static int clk_reg_set_target(struct cpufreq_policy *policy,
			  unsigned int target_freq, unsigned int relation)
{
	struct cpufreq_freqs freqs;
	unsigned long freq_Hz;
	int cpu;
	int ret = 0;
	unsigned int index;

	cpufreq_frequency_table_target(policy, freq_table,
			target_freq, relation, &index);
	freq_Hz = clk_round_rate(cpu_clk, cpu_freqs[index]);
	freq_Hz = freq_Hz ? freq_Hz : cpu_freqs[index];
	freqs.old = clk_get_rate(cpu_clk) / 1000;
	freqs.new = freq_Hz / 1000;
	freqs.flags = 0;

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

	for_each_possible_cpu(cpu) {
		freqs.cpu = cpu;
		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
	}

	ret = set_cpu_freq(freq_Hz, index, (freqs.new > freqs.old));
	if (ret)
		freqs.new = clk_get_rate(cpu_clk) / 1000;
	else
		cur_index = index;

	for_each_possible_cpu(cpu) {
		freqs.cpu = cpu;
		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
	}

	return ret;
}

static int clk_reg_cpufreq_init(struct cpufreq_policy *policy)
{
	int ret;

	if (policy->cpu >= num_possible_cpus())
		return -EINVAL;

	policy->cur = clk_get_rate(cpu_clk) / 1000;
	policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
	cpumask_setall(policy->cpus);
	policy->cpuinfo.transition_latency = trans_latency;

	ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);

	if (ret < 0) {
		pr_err("invalid frequency table for cpu %d\n",
			policy->cpu);
		return ret;
	}

	cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
	cpufreq_frequency_table_target(policy, freq_table, policy->cur,
					CPUFREQ_RELATION_H, &cur_index);
	return 0;
}

static int clk_reg_cpufreq_exit(struct cpufreq_policy *policy)
{
	cpufreq_frequency_table_put_attr(policy->cpu);
	return 0;
}

static struct cpufreq_driver clk_reg_cpufreq_driver = {
	.flags = CPUFREQ_STICKY,
	.verify = clk_reg_verify_speed,
	.target = clk_reg_set_target,
	.get = clk_reg_get_speed,
	.init = clk_reg_cpufreq_init,
	.exit = clk_reg_cpufreq_exit,
	.name = "clk-reg",
};


static u32 max_freq = UINT_MAX / 1000; /* kHz */
module_param(max_freq, uint, 0);
MODULE_PARM_DESC(max_freq, "max cpu frequency in unit of kHz");

static int __devinit clk_reg_cpufreq_driver_init(void)
{
	struct device_node *cpu0;
	const struct property *pp;
	int i, ret;

	cpu0 = of_find_node_by_path("/cpus/cpu@0");
	if (!cpu0)
		return -ENODEV;

	pp = of_find_property(cpu0, "cpu-freqs", NULL);
	if (!pp) {
		ret = -ENODEV;
		goto put_node;
	}
	cpu_op_nr = pp->length / sizeof(u32);
	if (!cpu_op_nr) {
		ret = -ENODEV;
		goto put_node;
	}
	ret = -ENOMEM;
	cpu_freqs = kzalloc(sizeof(*cpu_freqs) * cpu_op_nr, GFP_KERNEL);
	if (!cpu_freqs)
		goto put_node;
	of_property_read_u32_array(cpu0, "cpu-freqs", cpu_freqs, cpu_op_nr);

	pp = of_find_property(cpu0, "cpu-volts", NULL);
	if (pp) {
		if (cpu_op_nr * 2 == pp->length / sizeof(u32)) {
			cpu_volts = kzalloc(sizeof(*cpu_volts) * cpu_op_nr * 2,
						GFP_KERNEL);
			if (!cpu_volts)
				goto free_cpu_freqs;
			of_property_read_u32_array(cpu0, "cpu-volts",
						cpu_volts, cpu_op_nr * 2);
		} else
			pr_warn("invalid cpu_volts!\n");
	}

	if (of_property_read_u32(cpu0, "trans-latency", &trans_latency))
		trans_latency = CPUFREQ_ETERNAL;

	cpu_clk = clk_get(NULL, "cpu");
	if (IS_ERR(cpu_clk)) {
		pr_err("failed to get cpu clock\n");
		ret = PTR_ERR(cpu_clk);
		goto free_cpu_volts;
	}

	if (cpu_volts) {
		cpu_reg = regulator_get(NULL, "cpu");
		if (IS_ERR(cpu_reg)) {
			pr_warn("regulator cpu get failed.\n");
			cpu_reg = NULL;
		}
	}

	freq_table = kmalloc(sizeof(struct cpufreq_frequency_table)
				* (cpu_op_nr + 1), GFP_KERNEL);
	if (!freq_table) {
		ret = -ENOMEM;
		goto reg_put;
	}

	for (i = 0; i < cpu_op_nr; i++) {
		freq_table[i].index = i;
		if (cpu_freqs[i] > max_freq * 1000) {
			freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
			continue;
		}

		if (cpu_reg) {
			ret = regulator_is_supported_voltage(cpu_reg,
					cpu_volts[i * 2], cpu_volts[i * 2 + 1]);
			if (ret <= 0) {
				freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
				continue;
			}
		}
		freq_table[i].frequency = cpu_freqs[i] / 1000;
	}

	freq_table[i].index = i;
	freq_table[i].frequency = CPUFREQ_TABLE_END;

	ret = cpufreq_register_driver(&clk_reg_cpufreq_driver);
	if (ret)
		goto free_freq_table;

	of_node_put(cpu0);

	return 0;

free_freq_table:
	kfree(freq_table);
reg_put:
	if (cpu_reg)
		regulator_put(cpu_reg);
	clk_put(cpu_clk);
free_cpu_volts:
	kfree(cpu_volts);
free_cpu_freqs:
	kfree(cpu_freqs);
put_node:
	of_node_put(cpu0);

	return ret;
}

static void clk_reg_cpufreq_driver_exit(void)
{
	cpufreq_unregister_driver(&clk_reg_cpufreq_driver);
	kfree(cpu_freqs);
	kfree(cpu_volts);
	clk_put(cpu_clk);
	if (cpu_reg)
		regulator_put(cpu_reg);
	kfree(freq_table);
}

module_init(clk_reg_cpufreq_driver_init);
module_exit(clk_reg_cpufreq_driver_exit);

MODULE_AUTHOR("Freescale Semiconductor Inc. Richard Zhao <richard.zhao@freescale.com>");
MODULE_DESCRIPTION("Generic CPUFreq driver based on clk and regulator APIs");
MODULE_LICENSE("GPL");