mach-osiris-dvs.c

Go to the documentation of this file.

/* linux/arch/arm/mach-s3c2440/mach-osiris-dvs.c
 *
 * Copyright (c) 2009 Simtec Electronics
 *  http://armlinux.simtec.co.uk/
 *  Ben Dooks <[email protected]>
 *
 * Simtec Osiris Dynamic Voltage Scaling support.
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/cpufreq.h>
#include <linux/gpio.h>

#include <linux/i2c/tps65010.h>

#include <plat/cpu-freq.h>

#define OSIRIS_GPIO_DVS S3C2410_GPB(5)

static bool dvs_en;

static void osiris_dvs_tps_setdvs(bool on)
{
    unsigned vregs1 = 0, vdcdc2 = 0;

    if (!on) {
        vdcdc2 = TPS_VCORE_DISCH | TPS_LP_COREOFF;
        vregs1 = TPS_LDO1_OFF;  /* turn off in low-power mode */
    }

    dvs_en = on;
    vdcdc2 |= TPS_VCORE_1_3V | TPS_VCORE_LP_1_0V;
    vregs1 |= TPS_LDO2_ENABLE | TPS_LDO1_ENABLE;

    tps65010_config_vregs1(vregs1);
    tps65010_config_vdcdc2(vdcdc2);
}

static bool is_dvs(struct s3c_freq *f)
{
    /* at the moment, we assume ARMCLK = HCLK => DVS */
    return f->armclk == f->hclk;
}

/* keep track of current state */
static bool cur_dvs = false;

static int osiris_dvs_notify(struct notifier_block *nb,
                  unsigned long val, void *data)
{
    struct cpufreq_freqs *cf = data;
    struct s3c_cpufreq_freqs *freqs = to_s3c_cpufreq(cf);
    bool old_dvs = is_dvs(&freqs->old);
    bool new_dvs = is_dvs(&freqs->new);
    int ret = 0;

    if (!dvs_en)
        return 0;

    printk(KERN_DEBUG "%s: old %ld,%ld new %ld,%ld\n", __func__,
           freqs->old.armclk, freqs->old.hclk,
           freqs->new.armclk, freqs->new.hclk);

    switch (val) {
    case CPUFREQ_PRECHANGE:
        if (old_dvs & !new_dvs ||
            cur_dvs & !new_dvs) {
            pr_debug("%s: exiting dvs\n", __func__);
            cur_dvs = false;
            gpio_set_value(OSIRIS_GPIO_DVS, 1);
        }
        break;
    case CPUFREQ_POSTCHANGE:
        if (!old_dvs & new_dvs ||
            !cur_dvs & new_dvs) {
            pr_debug("entering dvs\n");
            cur_dvs = true;
            gpio_set_value(OSIRIS_GPIO_DVS, 0);
        }
        break;
    }

    return ret;
}

static struct notifier_block osiris_dvs_nb = {
    .notifier_call  = osiris_dvs_notify,
};

static int __devinit osiris_dvs_probe(struct platform_device *pdev)
{
    int ret;

    dev_info(&pdev->dev, "initialising\n");

    ret = gpio_request(OSIRIS_GPIO_DVS, "osiris-dvs");
    if (ret) {
        dev_err(&pdev->dev, "cannot claim gpio\n");
        goto err_nogpio;
    }

    /* start with dvs disabled */
    gpio_direction_output(OSIRIS_GPIO_DVS, 1);

    ret = cpufreq_register_notifier(&osiris_dvs_nb,
                    CPUFREQ_TRANSITION_NOTIFIER);
    if (ret) {
        dev_err(&pdev->dev, "failed to register with cpufreq\n");
        goto err_nofreq;
    }

    osiris_dvs_tps_setdvs(true);

    return 0;

err_nofreq:
    gpio_free(OSIRIS_GPIO_DVS);

err_nogpio:
    return ret;
}

static int __devexit osiris_dvs_remove(struct platform_device *pdev)
{
    dev_info(&pdev->dev, "exiting\n");

    /* disable any current dvs */
    gpio_set_value(OSIRIS_GPIO_DVS, 1);
    osiris_dvs_tps_setdvs(false);

    cpufreq_unregister_notifier(&osiris_dvs_nb,
                    CPUFREQ_TRANSITION_NOTIFIER);

    gpio_free(OSIRIS_GPIO_DVS);

    return 0;
}

/* the CONFIG_PM block is so small, it isn't worth actaully compiling it
 * out if the configuration isn't set. */

static int osiris_dvs_suspend(struct device *dev)
{
    gpio_set_value(OSIRIS_GPIO_DVS, 1);
    osiris_dvs_tps_setdvs(false);
    cur_dvs = false;

    return 0;
}

static int osiris_dvs_resume(struct device *dev)
{
    osiris_dvs_tps_setdvs(true);
    return 0;
}

static const struct dev_pm_ops osiris_dvs_pm = {
    .suspend    = osiris_dvs_suspend,
    .resume     = osiris_dvs_resume,
};

static struct platform_driver osiris_dvs_driver = {
    .probe      = osiris_dvs_probe,
    .remove     = __devexit_p(osiris_dvs_remove),
    .driver     = {
        .name   = "osiris-dvs",
        .owner  = THIS_MODULE,
        .pm = &osiris_dvs_pm,
    },
};

module_platform_driver(osiris_dvs_driver);

MODULE_DESCRIPTION("Simtec OSIRIS DVS support");
MODULE_AUTHOR("Ben Dooks <[email protected]>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:osiris-dvs");