/*
 * cpufreq driver for the SuperH processors.
 *
 * Copyright (C) 2002 - 2012 Paul Mundt
 * Copyright (C) 2002 M. R. Brown
 *
 * Clock framework bits from arch/avr32/mach-at32ap/cpufreq.c
 *
 *   Copyright (C) 2004-2007 Atmel Corporation
 *
 * 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 pr_fmt(fmt) "cpufreq: " fmt

#include <linux/types.h>
#include <linux/cpufreq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/cpumask.h>
#include <linux/cpu.h>
#include <linux/smp.h>
#include <linux/clk.h>
#include <linux/percpu.h>
#include <linux/sh_clk.h>

static DEFINE_PER_CPU(struct clk, sh_cpuclk);

struct cpufreq_target {
        struct cpufreq_policy   *policy;
        unsigned int            freq;
};

static unsigned int sh_cpufreq_get(unsigned int cpu)
{
        return (clk_get_rate(&per_cpu(sh_cpuclk, cpu)) + 500) / 1000;
}

static long __sh_cpufreq_target(void *arg)
{
        struct cpufreq_target *target = arg;
        struct cpufreq_policy *policy = target->policy;
        int cpu = policy->cpu;
        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
        struct cpufreq_freqs freqs;
        struct device *dev;
        long freq;

        if (smp_processor_id() != cpu)
                return -ENODEV;

        dev = get_cpu_device(cpu);

        /* Convert target_freq from kHz to Hz */
        freq = clk_round_rate(cpuclk, target->freq * 1000);

        if (freq < (policy->min * 1000) || freq > (policy->max * 1000))
                return -EINVAL;

        dev_dbg(dev, "requested frequency %u Hz\n", target->freq * 1000);

        freqs.old       = sh_cpufreq_get(cpu);
        freqs.new       = (freq + 500) / 1000;
        freqs.flags     = 0;

        cpufreq_freq_transition_begin(target->policy, &freqs);
        clk_set_rate(cpuclk, freq);
        cpufreq_freq_transition_end(target->policy, &freqs, 0);

        dev_dbg(dev, "set frequency %lu Hz\n", freq);
        return 0;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int sh_cpufreq_target(struct cpufreq_policy *policy,
                             unsigned int target_freq,
                             unsigned int relation)
{
        struct cpufreq_target data = { .policy = policy, .freq = target_freq };

        return work_on_cpu(policy->cpu, __sh_cpufreq_target, &data);
}

static int sh_cpufreq_verify(struct cpufreq_policy_data *policy)
{
        struct clk *cpuclk = &per_cpu(sh_cpuclk, policy->cpu);

        if (policy->freq_table)
                return cpufreq_frequency_table_verify(policy);

        cpufreq_verify_within_cpu_limits(policy);

        policy->min = (clk_round_rate(cpuclk, 1) + 500) / 1000;
        policy->max = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;

        cpufreq_verify_within_cpu_limits(policy);
        return 0;
}

static int sh_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
        unsigned int cpu = policy->cpu;
        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);
        struct cpufreq_frequency_table *freq_table;
        struct device *dev;

        dev = get_cpu_device(cpu);

        cpuclk = clk_get(dev, "cpu_clk");
        if (IS_ERR(cpuclk)) {
                dev_err(dev, "couldn't get CPU clk\n");
                return PTR_ERR(cpuclk);
        }

        freq_table = cpuclk->nr_freqs ? cpuclk->freq_table : NULL;
        if (freq_table) {
                policy->freq_table = freq_table;
        } else {
                dev_notice(dev, "no frequency table found, falling back "
                           "to rate rounding.\n");

                policy->min = policy->cpuinfo.min_freq =
                        (clk_round_rate(cpuclk, 1) + 500) / 1000;
                policy->max = policy->cpuinfo.max_freq =
                        (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
        }

        return 0;
}

static void sh_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
        unsigned int cpu = policy->cpu;
        struct clk *cpuclk = &per_cpu(sh_cpuclk, cpu);

        clk_put(cpuclk);
}

static struct cpufreq_driver sh_cpufreq_driver = {
        .name           = "sh",
        .flags          = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
        .get            = sh_cpufreq_get,
        .target         = sh_cpufreq_target,
        .verify         = sh_cpufreq_verify,
        .init           = sh_cpufreq_cpu_init,
        .exit           = sh_cpufreq_cpu_exit,
};

static int __init sh_cpufreq_module_init(void)
{
        pr_notice("SuperH CPU frequency driver.\n");
        return cpufreq_register_driver(&sh_cpufreq_driver);
}

static void __exit sh_cpufreq_module_exit(void)
{
        cpufreq_unregister_driver(&sh_cpufreq_driver);
}

module_init(sh_cpufreq_module_init);
module_exit(sh_cpufreq_module_exit);

MODULE_AUTHOR("Paul Mundt <lethal@linux-sh.org>");
MODULE_DESCRIPTION("cpufreq driver for SuperH");
MODULE_LICENSE("GPL");