/*
 * Cpufreq driver for the loongson-2 processors
 *
 * The 2E revision of loongson processor not support this feature.
 *
 * Copyright (C) 2006 - 2008 Lemote Inc. & Institute 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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/cpufreq.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/platform_device.h>

#include <asm/idle.h>

#include <asm/mach-loongson2ef/loongson.h>

static uint nowait;

static void (*saved_cpu_wait) (void);

static int loongson2_cpu_freq_notifier(struct notifier_block *nb,
                                        unsigned long val, void *data);

static struct notifier_block loongson2_cpufreq_notifier_block = {
        .notifier_call = loongson2_cpu_freq_notifier
};

static int loongson2_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;
}

/*
 * Here we notify other drivers of the proposed change and the final change.
 */
static int loongson2_cpufreq_target(struct cpufreq_policy *policy,
                                     unsigned int index)
{
        unsigned int freq;

        freq =
            ((cpu_clock_freq / 1000) *
             loongson2_clockmod_table[index].driver_data) / 8;

        /* setting the cpu frequency */
        loongson2_cpu_set_rate(freq);

        return 0;
}

static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
        int i;
        unsigned long rate;
        int ret;

        rate = cpu_clock_freq / 1000;
        if (!rate)
                return -EINVAL;

        /* clock table init */
        for (i = 2;
             (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END);
             i++)
                loongson2_clockmod_table[i].frequency = (rate * i) / 8;

        ret = loongson2_cpu_set_rate(rate);
        if (ret)
                return ret;

        cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0);
        return 0;
}

static struct cpufreq_driver loongson2_cpufreq_driver = {
        .name = "loongson2",
        .init = loongson2_cpufreq_cpu_init,
        .verify = cpufreq_generic_frequency_table_verify,
        .target_index = loongson2_cpufreq_target,
        .get = cpufreq_generic_get,
};

static const struct platform_device_id platform_device_ids[] = {
        {
                .name = "loongson2_cpufreq",
        },
        {}
};

MODULE_DEVICE_TABLE(platform, platform_device_ids);

static struct platform_driver platform_driver = {
        .driver = {
                .name = "loongson2_cpufreq",
        },
        .id_table = platform_device_ids,
};

/*
 * This is the simple version of Loongson-2 wait, Maybe we need do this in
 * interrupt disabled context.
 */

static DEFINE_SPINLOCK(loongson2_wait_lock);

static void loongson2_cpu_wait(void)
{
        unsigned long flags;
        u32 cpu_freq;

        spin_lock_irqsave(&loongson2_wait_lock, flags);
        cpu_freq = readl(LOONGSON_CHIPCFG);
        /* Put CPU into wait mode */
        writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG);
        /* Restore CPU state */
        writel(cpu_freq, LOONGSON_CHIPCFG);
        spin_unlock_irqrestore(&loongson2_wait_lock, flags);
        local_irq_enable();
}

static int __init cpufreq_init(void)
{
        int ret;

        /* Register platform stuff */
        ret = platform_driver_register(&platform_driver);
        if (ret)
                return ret;

        pr_info("Loongson-2F CPU frequency driver\n");

        cpufreq_register_notifier(&loongson2_cpufreq_notifier_block,
                                  CPUFREQ_TRANSITION_NOTIFIER);

        ret = cpufreq_register_driver(&loongson2_cpufreq_driver);

        if (ret) {
                platform_driver_unregister(&platform_driver);
        } else if (!nowait) {
                saved_cpu_wait = cpu_wait;
                cpu_wait = loongson2_cpu_wait;
        }

        return ret;
}

static void __exit cpufreq_exit(void)
{
        if (!nowait && saved_cpu_wait)
                cpu_wait = saved_cpu_wait;
        cpufreq_unregister_driver(&loongson2_cpufreq_driver);
        cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block,
                                    CPUFREQ_TRANSITION_NOTIFIER);

        platform_driver_unregister(&platform_driver);
}

module_init(cpufreq_init);
module_exit(cpufreq_exit);

module_param(nowait, uint, 0644);
MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait");

MODULE_AUTHOR("Yanhua <yanh@lemote.com>");
MODULE_DESCRIPTION("cpufreq driver for Loongson2F");
MODULE_LICENSE("GPL");