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dpmc.c

/*
 * Copyright 2008 Analog Devices Inc.
 *
 * Licensed under the GPL-2 or later.
 */

#include <linux/cdev.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/cpufreq.h>

#include <asm/delay.h>
#include <asm/dpmc.h>

#define DRIVER_NAME "bfin dpmc"

#define dprintk(msg...) \
      cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, DRIVER_NAME, msg)

struct bfin_dpmc_platform_data *pdata;

/**
 *    bfin_set_vlev - Update VLEV field in VR_CTL Reg.
 *                Avoid BYPASS sequence
 */
static void bfin_set_vlev(unsigned int vlev)
{
      unsigned pll_lcnt;

      pll_lcnt = bfin_read_PLL_LOCKCNT();

      bfin_write_PLL_LOCKCNT(1);
      bfin_write_VR_CTL((bfin_read_VR_CTL() & ~VLEV) | vlev);
      bfin_write_PLL_LOCKCNT(pll_lcnt);
}

/**
 *    bfin_get_vlev - Get CPU specific VLEV from platform device data
 */
static unsigned int bfin_get_vlev(unsigned int freq)
{
      int i;

      if (!pdata)
            goto err_out;

      freq >>= 16;

      for (i = 0; i < pdata->tabsize; i++)
            if (freq <= (pdata->tuple_tab[i] & 0xFFFF))
                  return pdata->tuple_tab[i] >> 16;

err_out:
      printk(KERN_WARNING "DPMC: No suitable CCLK VDDINT voltage pair found\n");
      return VLEV_120;
}

#ifdef CONFIG_CPU_FREQ
static int
vreg_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
{
      struct cpufreq_freqs *freq = data;

      if (val == CPUFREQ_PRECHANGE && freq->old < freq->new) {
            bfin_set_vlev(bfin_get_vlev(freq->new));
            udelay(pdata->vr_settling_time); /* Wait until Volatge settled */

      } else if (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)
            bfin_set_vlev(bfin_get_vlev(freq->new));

      return 0;
}

static struct notifier_block vreg_cpufreq_notifier_block = {
      .notifier_call    = vreg_cpufreq_notifier
};
#endif /* CONFIG_CPU_FREQ */

/**
 *    bfin_dpmc_probe -
 *
 */
static int __devinit bfin_dpmc_probe(struct platform_device *pdev)
{
      if (pdev->dev.platform_data)
            pdata = pdev->dev.platform_data;
      else
            return -EINVAL;

      return cpufreq_register_notifier(&vreg_cpufreq_notifier_block,
                               CPUFREQ_TRANSITION_NOTIFIER);
}

/**
 *    bfin_dpmc_remove -
 */
static int __devexit bfin_dpmc_remove(struct platform_device *pdev)
{
      pdata = NULL;
      return cpufreq_unregister_notifier(&vreg_cpufreq_notifier_block,
                               CPUFREQ_TRANSITION_NOTIFIER);
}

struct platform_driver bfin_dpmc_device_driver = {
      .probe   = bfin_dpmc_probe,
      .remove  = __devexit_p(bfin_dpmc_remove),
      .driver  = {
            .name = DRIVER_NAME,
      }
};

/**
 *    bfin_dpmc_init - Init driver
 */
static int __init bfin_dpmc_init(void)
{
      return platform_driver_register(&bfin_dpmc_device_driver);
}
module_init(bfin_dpmc_init);

/**
 *    bfin_dpmc_exit - break down driver
 */
static void __exit bfin_dpmc_exit(void)
{
      platform_driver_unregister(&bfin_dpmc_device_driver);
}
module_exit(bfin_dpmc_exit);

MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
MODULE_DESCRIPTION("cpu power management driver for Blackfin");
MODULE_LICENSE("GPL");

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