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 # ifdef CONFIG_SMP
  65 static void bfin_idle_this_cpu(void *info)
  66 {
  67         unsigned long flags = 0;
  68         unsigned long iwr0, iwr1, iwr2;
  69         unsigned int cpu = smp_processor_id();
  70
  71         local_irq_save_hw(flags);
  72         bfin_iwr_set_sup0(&iwr0, &iwr1, &iwr2);
  73
  74         platform_clear_ipi(cpu, IRQ_SUPPLE_0);
  75         SSYNC();
  76         asm("IDLE;");
  77         bfin_iwr_restore(iwr0, iwr1, iwr2);
  78
  79         local_irq_restore_hw(flags);
  80 }
  81
  82 static void bfin_idle_cpu(void)
  83 {
  84         smp_call_function(bfin_idle_this_cpu, NULL, 0);
  85 }
  86
  87 static void bfin_wakeup_cpu(void)
  88 {
  89         unsigned int cpu;
  90         unsigned int this_cpu = smp_processor_id();
  91         cpumask_t mask = cpu_online_map;
  92
  93         cpu_clear(this_cpu, mask);
  94         for_each_cpu_mask(cpu, mask)
  95                 platform_send_ipi_cpu(cpu, IRQ_SUPPLE_0);
  96 }
  97
  98 # else
  99 static void bfin_idle_cpu(void) {}
 100 static void bfin_wakeup_cpu(void) {}
 101 # endif
 102
 103 static int
 104 vreg_cpufreq_notifier(struct notifier_block *nb, unsigned long val, void *data)
 105 {
 106         struct cpufreq_freqs *freq = data;
 107
 108         if (freq->cpu != CPUFREQ_CPU)
 109                 return 0;
 110
 111         if (val == CPUFREQ_PRECHANGE && freq->old < freq->new) {
 112                 bfin_idle_cpu();
 113                 bfin_set_vlev(bfin_get_vlev(freq->new));
 114                 udelay(pdata->vr_settling_time); /* Wait until Volatge settled */
 115                 bfin_wakeup_cpu();
 116         } else if (val == CPUFREQ_POSTCHANGE && freq->old > freq->new) {
 117                 bfin_idle_cpu();
 118                 bfin_set_vlev(bfin_get_vlev(freq->new));
 119                 bfin_wakeup_cpu();
 120         }
 121
 122         return 0;
 123 }
 124
 125 static struct notifier_block vreg_cpufreq_notifier_block = {
 126         .notifier_call  = vreg_cpufreq_notifier
 127 };
 128 #endif /* CONFIG_CPU_FREQ */
 129
 130 /**
 131  *      bfin_dpmc_probe -
 132  *
 133  */
 134 static int __devinit bfin_dpmc_probe(struct platform_device *pdev)
 135 {
 136         if (pdev->dev.platform_data)
 137                 pdata = pdev->dev.platform_data;
 138         else
 139                 return -EINVAL;
 140
 141         return cpufreq_register_notifier(&vreg_cpufreq_notifier_block,
 142                                          CPUFREQ_TRANSITION_NOTIFIER);
 143 }
 144
 145 /**
 146  *      bfin_dpmc_remove -
 147  */
 148 static int __devexit bfin_dpmc_remove(struct platform_device *pdev)
 149 {
 150         pdata = NULL;
 151         return cpufreq_unregister_notifier(&vreg_cpufreq_notifier_block,
 152                                          CPUFREQ_TRANSITION_NOTIFIER);
 153 }
 154
 155 struct platform_driver bfin_dpmc_device_driver = {
 156         .probe   = bfin_dpmc_probe,
 157         .remove  = __devexit_p(bfin_dpmc_remove),
 158         .driver  = {
 159                 .name = DRIVER_NAME,
 160         }
 161 };
 162
 163 /**
 164  *      bfin_dpmc_init - Init driver
 165  */
 166 static int __init bfin_dpmc_init(void)
 167 {
 168         return platform_driver_register(&bfin_dpmc_device_driver);
 169 }
 170 module_init(bfin_dpmc_init);
 171
 172 /**
 173  *      bfin_dpmc_exit - break down driver
 174  */
 175 static void __exit bfin_dpmc_exit(void)
 176 {
 177         platform_driver_unregister(&bfin_dpmc_device_driver);
 178 }
 179 module_exit(bfin_dpmc_exit);
 180
 181 MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>");
 182 MODULE_DESCRIPTION("cpu power management driver for Blackfin");
 183 MODULE_LICENSE("GPL");