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mach-osiris-dvs.c

/* linux/arch/arm/mach-s3c2440/mach-osiris-dvs.c
 *
 * Copyright (c) 2009 Simtec Electronics
 *    http://armlinux.simtec.co.uk/
 *    Ben Dooks <ben@simtec.co.uk>
 *
 * 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,
      },
};

static int __init osiris_dvs_init(void)
{
      return platform_driver_register(&osiris_dvs_driver);
}

static void __exit osiris_dvs_exit(void)
{
      platform_driver_unregister(&osiris_dvs_driver);
}

module_init(osiris_dvs_init);
module_exit(osiris_dvs_exit);

MODULE_DESCRIPTION("Simtec OSIRIS DVS support");
MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:osiris-dvs");

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