arch/blackfin/mach-common/dpmc.c

   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
  25 struct bfin_dpmc_platform_data *pdata;
  26
  27 /**
  28  *      bfin_set_vlev - Update VLEV field in VR_CTL Reg.
  29  *                      Avoid BYPASS sequence
  30  */
  31 static 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  */
  45 static 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
  58 err_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
  64 static int
  65 vreg_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
  79 static 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  */
  88 static 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  */
 102 static 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
 109 struct 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  */
 120 static int __init bfin_dpmc_init(void)
 121 {
 122         return platform_driver_register(&bfin_dpmc_device_driver);
 123 }
 124 module_init(bfin_dpmc_init);
 125
 126 /**
 127  *      bfin_dpmc_exit - break down driver
 128  */
 129 static void __exit bfin_dpmc_exit(void)
 130 {
 131         platform_driver_unregister(&bfin_dpmc_device_driver);
 132 }
 133 module_exit(bfin_dpmc_exit);
 134
 135 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 136 MODULE_DESCRIPTION("cpu power management driver for Blackfin");
 137 MODULE_LICENSE("GPL");