/*
 * CPU frequency scaling for DaVinci
 *
 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
 *
 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
 *
 *  Copyright (C) 2005 Nokia Corporation
 *  Written by Tony Lindgren <tony@atomide.com>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 * Updated to support OMAP3
 * Rajendra Nayak <rnayak@ti.com>
 *
 * 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/types.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/platform_device.h>
#include <linux/export.h>

#include <mach/hardware.h>
#include <mach/cpufreq.h>
#include <mach/common.h>

struct davinci_cpufreq {
        struct device *dev;
        struct clk *armclk;
        struct clk *asyncclk;
        unsigned long asyncrate;
};
static struct davinci_cpufreq cpufreq;

static int davinci_verify_speed(struct cpufreq_policy *policy)
{
        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
        struct cpufreq_frequency_table *freq_table = pdata->freq_table;
        struct clk *armclk = cpufreq.armclk;

        if (freq_table)
                return cpufreq_frequency_table_verify(policy, freq_table);

        if (policy->cpu)
                return -EINVAL;

        cpufreq_verify_within_cpu_limits(policy);
        policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
        policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
                                                policy->cpuinfo.max_freq);
        return 0;
}

static unsigned int davinci_getspeed(unsigned int cpu)
{
        if (cpu)
                return 0;

        return clk_get_rate(cpufreq.armclk) / 1000;
}

static int davinci_target(struct cpufreq_policy *policy,
                                unsigned int target_freq, unsigned int relation)
{
        int ret = 0;
        unsigned int idx;
        struct cpufreq_freqs freqs;
        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
        struct clk *armclk = cpufreq.armclk;

        freqs.old = davinci_getspeed(0);
        freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;

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

        dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);

        ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
                                                freqs.new, relation, &idx);
        if (ret)
                return -EINVAL;

        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);

        /* if moving to higher frequency, up the voltage beforehand */
        if (pdata->set_voltage && freqs.new > freqs.old) {
                ret = pdata->set_voltage(idx);
                if (ret)
                        goto out;
        }

        ret = clk_set_rate(armclk, idx);
        if (ret)
                goto out;

        if (cpufreq.asyncclk) {
                ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
                if (ret)
                        goto out;
        }

        /* if moving to lower freq, lower the voltage after lowering freq */
        if (pdata->set_voltage && freqs.new < freqs.old)
                pdata->set_voltage(idx);

out:
        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);

        return ret;
}

static int davinci_cpu_init(struct cpufreq_policy *policy)
{
        int result = 0;
        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
        struct cpufreq_frequency_table *freq_table = pdata->freq_table;

        if (policy->cpu != 0)
                return -EINVAL;

        /* Finish platform specific initialization */
        if (pdata->init) {
                result = pdata->init();
                if (result)
                        return result;
        }

        policy->cur = davinci_getspeed(0);

        result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
        if (result) {
                pr_err("%s: cpufreq_frequency_table_cpuinfo() failed",
                                __func__);
                return result;
        }

        cpufreq_frequency_table_get_attr(freq_table, policy->cpu);

        /*
         * Time measurement across the target() function yields ~1500-1800us
         * time taken with no drivers on notification list.
         * Setting the latency to 2000 us to accommodate addition of drivers
         * to pre/post change notification list.
         */
        policy->cpuinfo.transition_latency = 2000 * 1000;
        return 0;
}

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

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

static struct cpufreq_driver davinci_driver = {
        .flags          = CPUFREQ_STICKY,
        .verify         = davinci_verify_speed,
        .target         = davinci_target,
        .get            = davinci_getspeed,
        .init           = davinci_cpu_init,
        .exit           = davinci_cpu_exit,
        .name           = "davinci",
        .attr           = davinci_cpufreq_attr,
};

static int __init davinci_cpufreq_probe(struct platform_device *pdev)
{
        struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
        struct clk *asyncclk;

        if (!pdata)
                return -EINVAL;
        if (!pdata->freq_table)
                return -EINVAL;

        cpufreq.dev = &pdev->dev;

        cpufreq.armclk = clk_get(NULL, "arm");
        if (IS_ERR(cpufreq.armclk)) {
                dev_err(cpufreq.dev, "Unable to get ARM clock\n");
                return PTR_ERR(cpufreq.armclk);
        }

        asyncclk = clk_get(cpufreq.dev, "async");
        if (!IS_ERR(asyncclk)) {
                cpufreq.asyncclk = asyncclk;
                cpufreq.asyncrate = clk_get_rate(asyncclk);
        }

        return cpufreq_register_driver(&davinci_driver);
}

static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
{
        clk_put(cpufreq.armclk);

        if (cpufreq.asyncclk)
                clk_put(cpufreq.asyncclk);

        return cpufreq_unregister_driver(&davinci_driver);
}

static struct platform_driver davinci_cpufreq_driver = {
        .driver = {
                .name    = "cpufreq-davinci",
                .owner   = THIS_MODULE,
        },
        .remove = __exit_p(davinci_cpufreq_remove),
};

int __init davinci_cpufreq_init(void)
{
        return platform_driver_probe(&davinci_cpufreq_driver,
                                                        davinci_cpufreq_probe);
}