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 struct bfin_dpmc_platform_data *pdata;
  23
  24 /**
  25  *      bfin_set_vlev - Update VLEV field in VR_CTL Reg.
  26  *                      Avoid BYPASS sequence
  27  */
  28 static void bfin_set_vlev(unsigned int vlev)
  29 {
  30         unsigned pll_lcnt;
  31
  32         pll_lcnt = bfin_read_PLL_LOCKCNT();
  33
  34         bfin_write_PLL_LOCKCNT(1);
  35         bfin_write_VR_CTL((bfin_read_VR_CTL() & ~VLEV) | vlev);
  36         bfin_write_PLL_LOCKCNT(pll_lcnt);
  37 }
  38
  39 /**
  40  *      bfin_get_vlev - Get CPU specific VLEV from platform device data
  41  */
  42 static unsigned int bfin_get_vlev(unsigned int freq)
  43 {
  44         int i;
  45
  46         if (!pdata)
  47                 goto err_out;
  48
  49         freq >>= 16;
  50
  51         for (i = 0; i < pdata->tabsize; i++)
  52                 if (freq <= (pdata->tuple_tab[i] & 0xFFFF))
  53                         return pdata->tuple_tab[i] >> 16;
  54
  55 err_out:
  56         printk(KERN_WARNING "DPMC: No suitable CCLK VDDINT voltage pair found\n");
  57         return VLEV_120;
  58 }
  59
  60 #ifdef CONFIG_CPU_FREQ
  61 # ifdef CONFIG_SMP
  62 static void bfin_idle_this_cpu(void *info)
  63 {
  64         unsigned long flags = 0;
  65         unsigned long iwr0, iwr1, iwr2;
  66         unsigned int cpu = smp_processor_id();
  67
  68         local_irq_save_hw(flags);
  69         bfin_iwr_set_sup0(&iwr0, &iwr1, &iwr2);
  70
  71         platform_clear_ipi(cpu, IRQ_SUPPLE_0);
  72         SSYNC();
  73         asm("IDLE;");
  74         bfin_iwr_restore(iwr0, iwr1, iwr2);
  75
  76         local_irq_restore_hw(flags);
  77 }
  78
  79 static void bfin_idle_cpu(void)
  80 {
  81         smp_call_function(bfin_idle_this_cpu, NULL, 0);
  82 }
  83
  84 static void bfin_wakeup_cpu(void)
  85 {
  86         unsigned int cpu;
  87         unsigned int this_cpu = smp_processor_id();
  88         cpumask_t mask;
  89
  90         cpumask_copy(&mask, cpu_online_mask);
  91         cpumask_clear_cpu(this_cpu, &mask);
  92         for_each_cpu(cpu, &mask)
  93                 platform_send_ipi_cpu(cpu, IRQ_SUPPLE_0);
  94 }
  95
  96 # else
  97 static void bfin_idle_cpu(void) {}
  98 static void bfin_wakeup_cpu(void) {}
  99 # endif
 100
 101 static int
 102 vreg_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
 103 {
 104         struct cpufreq_freqs *freq = data;
 105
 106         if (freq->cpu != CPUFREQ_CPU)
 107                 return 0;
 108
 109         if (val == CPUFREQ_PRECHANGE && freq->old < freq->new) {
 110                 bfin_idle_cpu();
 111                 bfin_set_vlev(bfin_get_vlev(freq->new));
 112                 udelay(pdata->vr_settling_time); /* Wait until Volatge settled */
 113                 bfin_wakeup_cpu();
 114         } else if (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) {
 115                 bfin_idle_cpu();
 116                 bfin_set_vlev(bfin_get_vlev(freq->new));
 117                 bfin_wakeup_cpu();
 118         }
 119
 120         return 0;
 121 }
 122
 123 static struct notifier_block vreg_cpufreq_notifier_block = {
 124         .notifier_call  = vreg_cpufreq_notifier
 125 };
 126 #endif /* CONFIG_CPU_FREQ */
 127
 128 /**
 129  *      bfin_dpmc_probe -
 130  *
 131  */
 132 static int __devinit bfin_dpmc_probe(struct platform_device *pdev)
 133 {
 134         if (pdev->dev.platform_data)
 135                 pdata = pdev->dev.platform_data;
 136         else
 137                 return -EINVAL;
 138
 139         return cpufreq_register_notifier(&vreg_cpufreq_notifier_block,
 140                                          CPUFREQ_TRANSITION_NOTIFIER);
 141 }
 142
 143 /**
 144  *      bfin_dpmc_remove -
 145  */
 146 static int __devexit bfin_dpmc_remove(struct platform_device *pdev)
 147 {
 148         pdata = NULL;
 149         return cpufreq_unregister_notifier(&vreg_cpufreq_notifier_block,
 150                                          CPUFREQ_TRANSITION_NOTIFIER);
 151 }
 152
 153 struct platform_driver bfin_dpmc_device_driver = {
 154         .probe   = bfin_dpmc_probe,
 155         .remove  = __devexit_p(bfin_dpmc_remove),
 156         .driver  = {
 157                 .name = DRIVER_NAME,
 158         }
 159 };
 160
 161 /**
 162  *      bfin_dpmc_init - Init driver
 163  */
 164 static int __init bfin_dpmc_init(void)
 165 {
 166         return platform_driver_register(&bfin_dpmc_device_driver);
 167 }
 168 module_init(bfin_dpmc_init);
 169
 170 /**
 171  *      bfin_dpmc_exit - break down driver
 172  */
 173 static void __exit bfin_dpmc_exit(void)
 174 {
 175         platform_driver_unregister(&bfin_dpmc_device_driver);
 176 }
 177 module_exit(bfin_dpmc_exit);
 178
 179 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 180 MODULE_DESCRIPTION("cpu power management driver for Blackfin");
 181 MODULE_LICENSE("GPL");