linux/arch/blackfin/mach-common/dpmc.c
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   1/*
   2 * Copyright 2008 Analog Devices Inc.
   3 *
   4 * Licensed under the GPL-2 or later.
   5 */
   6
   7#include <linux/cdev.h>
   8#include <linux/device.h>
   9#include <linux/errno.h>
  10#include <linux/fs.h>
  11#include <linux/kernel.h>
  12#include <linux/module.h>
  13#include <linux/platform_device.h>
  14#include <linux/types.h>
  15#include <linux/cpufreq.h>
  16
  17#include <asm/delay.h>
  18#include <asm/dpmc.h>
  19
  20#define DRIVER_NAME "bfin dpmc"
  21
  22#define dprintk(msg...) \
  23        cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, DRIVER_NAME, msg)
  24
  25struct bfin_dpmc_platform_data *pdata;
  26
  27/**
  28 *      bfin_set_vlev - Update VLEV field in VR_CTL Reg.
  29 *                      Avoid BYPASS sequence
  30 */
  31static void bfin_set_vlev(unsigned int vlev)
  32{
  33        unsigned pll_lcnt;
  34
  35        pll_lcnt = bfin_read_PLL_LOCKCNT();
  36
  37        bfin_write_PLL_LOCKCNT(1);
  38        bfin_write_VR_CTL((bfin_read_VR_CTL() & ~VLEV) | vlev);
  39        bfin_write_PLL_LOCKCNT(pll_lcnt);
  40}
  41
  42/**
  43 *      bfin_get_vlev - Get CPU specific VLEV from platform device data
  44 */
  45static unsigned int bfin_get_vlev(unsigned int freq)
  46{
  47        int i;
  48
  49        if (!pdata)
  50                goto err_out;
  51
  52        freq >>= 16;
  53
  54        for (i = 0; i < pdata->tabsize; i++)
  55                if (freq <= (pdata->tuple_tab[i] & 0xFFFF))
  56                        return pdata->tuple_tab[i] >> 16;
  57
  58err_out:
  59        printk(KERN_WARNING "DPMC: No suitable CCLK VDDINT voltage pair found\n");
  60        return VLEV_120;
  61}
  62
  63#ifdef CONFIG_CPU_FREQ
  64static int
  65vreg_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
  66{
  67        struct cpufreq_freqs *freq = data;
  68
  69        if (val == CPUFREQ_PRECHANGE && freq->old < freq->new) {
  70                bfin_set_vlev(bfin_get_vlev(freq->new));
  71                udelay(pdata->vr_settling_time); /* Wait until Volatge settled */
  72
  73        } else if (val == CPUFREQ_POSTCHANGE && freq->old > freq->new)
  74                bfin_set_vlev(bfin_get_vlev(freq->new));
  75
  76        return 0;
  77}
  78
  79static struct notifier_block vreg_cpufreq_notifier_block = {
  80        .notifier_call  = vreg_cpufreq_notifier
  81};
  82#endif /* CONFIG_CPU_FREQ */
  83
  84/**
  85 *      bfin_dpmc_probe -
  86 *
  87 */
  88static int __devinit bfin_dpmc_probe(struct platform_device *pdev)
  89{
  90        if (pdev->dev.platform_data)
  91                pdata = pdev->dev.platform_data;
  92        else
  93                return -EINVAL;
  94
  95        return cpufreq_register_notifier(&vreg_cpufreq_notifier_block,
  96                                         CPUFREQ_TRANSITION_NOTIFIER);
  97}
  98
  99/**
 100 *      bfin_dpmc_remove -
 101 */
 102static int __devexit bfin_dpmc_remove(struct platform_device *pdev)
 103{
 104        pdata = NULL;
 105        return cpufreq_unregister_notifier(&vreg_cpufreq_notifier_block,
 106                                         CPUFREQ_TRANSITION_NOTIFIER);
 107}
 108
 109struct platform_driver bfin_dpmc_device_driver = {
 110        .probe   = bfin_dpmc_probe,
 111        .remove  = __devexit_p(bfin_dpmc_remove),
 112        .driver  = {
 113                .name = DRIVER_NAME,
 114        }
 115};
 116
 117/**
 118 *      bfin_dpmc_init - Init driver
 119 */
 120static int __init bfin_dpmc_init(void)
 121{
 122        return platform_driver_register(&bfin_dpmc_device_driver);
 123}
 124module_init(bfin_dpmc_init);
 125
 126/**
 127 *      bfin_dpmc_exit - break down driver
 128 */
 129static void __exit bfin_dpmc_exit(void)
 130{
 131        platform_driver_unregister(&bfin_dpmc_device_driver);
 132}
 133module_exit(bfin_dpmc_exit);
 134
 135MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 136MODULE_DESCRIPTION("cpu power management driver for Blackfin");
 137MODULE_LICENSE("GPL");
 138