cpufreq.c

Go to the documentation of this file.

/*
 * 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 <[email protected]>
 *
 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 *
 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 * Updated to support OMAP3
 * Rajendra Nayak <[email protected]>
 *
 * 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>

#include "clock.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_limits(policy, policy->cpuinfo.min_freq,
                     policy->cpuinfo.max_freq);

    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;

    /*
     * Ensure desired rate is within allowed range.  Some govenors
     * (ondemand) will just pass target_freq=0 to get the minimum.
     */
    if (target_freq < policy->cpuinfo.min_freq)
        target_freq = policy->cpuinfo.min_freq;
    if (target_freq > policy->cpuinfo.max_freq)
        target_freq = policy->cpuinfo.max_freq;

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

    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(&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(&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 = policy->min = policy->max = davinci_getspeed(0);

    if (freq_table) {
        result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
        if (!result)
            cpufreq_frequency_table_get_attr(freq_table,
                            policy->cpu);
    } else {
        policy->cpuinfo.min_freq = policy->min;
        policy->cpuinfo.max_freq = policy->max;
    }

    policy->min = policy->cpuinfo.min_freq;
    policy->max = policy->cpuinfo.max_freq;
    policy->cur = davinci_getspeed(0);

    /*
     * 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);
}