linux-imx

/*

 * 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_data/davinci-cpufreq.h>

#include <linux/platform_device.h>

#include <linux/export.h>

​

struct davinci_cpufreq {

    struct device *dev;

    struct clk *armclk;

    struct clk *asyncclk;

    unsigned long asyncrate;

};

static struct davinci_cpufreq cpufreq;

​

static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)

{

    struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;

    struct clk *armclk = cpufreq.armclk;

    unsigned int old_freq, new_freq;

    int ret = 0;

​

    old_freq = policy->cur;

    new_freq = pdata->freq_table[idx].frequency;

​

    /* if moving to higher frequency, up the voltage beforehand */

    if (pdata->set_voltage && new_freq > old_freq) {

        ret = pdata->set_voltage(idx);

        if (ret)

            return ret;

    }

​

    ret = clk_set_rate(armclk, new_freq * 1000);

    if (ret)

        return ret;

​

    if (cpufreq.asyncclk) {

        ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);

        if (ret)

            return ret;

    }

​

    /* if moving to lower freq, lower the voltage after lowering freq */

    if (pdata->set_voltage && new_freq < old_freq)

        pdata->set_voltage(idx);

​

    return 0;

}

​

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->clk = cpufreq.armclk;

​

    /*

     * Time measurement across the target() function yields ~1500-1800us

     * time taken with no drivers on notification list.