arch/arm/mach-davinci/cpuidle.c

   1 /*
   2  * CPU idle for DaVinci SoCs
   3  *
   4  * Copyright (C) 2009 Texas Instruments Incorporated. http://www.ti.com/
   5  *
   6  * Derived from Marvell Kirkwood CPU idle code
   7  * (arch/arm/mach-kirkwood/cpuidle.c)
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/cpuidle.h>
  18 #include <linux/io.h>
  19 #include <asm/proc-fns.h>
  20
  21 #include <mach/cpuidle.h>
  22 #include <mach/memory.h>
  23
  24 #define DAVINCI_CPUIDLE_MAX_STATES      2
  25
  26 struct davinci_ops {
  27         void (*enter) (u32 flags);
  28         void (*exit) (u32 flags);
  29         u32 flags;
  30 };
  31
  32 /* fields in davinci_ops.flags */
  33 #define DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN BIT(0)
  34
  35 static struct cpuidle_driver davinci_idle_driver = {
  36         .name   = "cpuidle-davinci",
  37         .owner  = THIS_MODULE,
  38 };
  39
  40 static DEFINE_PER_CPU(struct cpuidle_device, davinci_cpuidle_device);
  41 static void __iomem *ddr2_reg_base;
  42
  43 static void davinci_save_ddr_power(int enter, bool pdown)
  44 {
  45         u32 val;
  46
  47         val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
  48
  49         if (enter) {
  50                 if (pdown)
  51                         val |= DDR2_SRPD_BIT;
  52                 else
  53                         val &= ~DDR2_SRPD_BIT;
  54                 val |= DDR2_LPMODEN_BIT;
  55         } else {
  56                 val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
  57         }
  58
  59         __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
  60 }
  61
  62 static void davinci_c2state_enter(u32 flags)
  63 {
  64         davinci_save_ddr_power(1, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
  65 }
  66
  67 static void davinci_c2state_exit(u32 flags)
  68 {
  69         davinci_save_ddr_power(0, !!(flags & DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN));
  70 }
  71
  72 static struct davinci_ops davinci_states[DAVINCI_CPUIDLE_MAX_STATES] = {
  73         [1] = {
  74                 .enter  = davinci_c2state_enter,
  75                 .exit   = davinci_c2state_exit,
  76         },
  77 };
  78
  79 /* Actual code that puts the SoC in different idle states */
  80 static int davinci_enter_idle(struct cpuidle_device *dev,
  81                                 struct cpuidle_driver *drv,
  82                                                 int index)
  83 {
  84         struct cpuidle_state_usage *state_usage = &dev->states_usage[index];
  85         struct davinci_ops *ops = cpuidle_get_statedata(state_usage);
  86         struct timeval before, after;
  87         int idle_time;
  88
  89         local_irq_disable();
  90         do_gettimeofday(&before);
  91
  92         if (ops && ops->enter)
  93                 ops->enter(ops->flags);
  94         /* Wait for interrupt state */
  95         cpu_do_idle();
  96         if (ops && ops->exit)
  97                 ops->exit(ops->flags);
  98
  99         do_gettimeofday(&after);
 100         local_irq_enable();
 101         idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
 102                         (after.tv_usec - before.tv_usec);
 103
 104         dev->last_residency = idle_time;
 105
 106         return index;
 107 }
 108
 109 static int __init davinci_cpuidle_probe(struct platform_device *pdev)
 110 {
 111         int ret;
 112         struct cpuidle_device *device;
 113         struct cpuidle_driver *driver = &davinci_idle_driver;
 114         struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
 115
 116         device = &per_cpu(davinci_cpuidle_device, smp_processor_id());
 117
 118         if (!pdata) {
 119                 dev_err(&pdev->dev, "cannot get platform data\n");
 120                 return -ENOENT;
 121         }
 122
 123         ddr2_reg_base = pdata->ddr2_ctlr_base;
 124
 125         /* Wait for interrupt state */
 126         driver->states[0].enter = davinci_enter_idle;
 127         driver->states[0].exit_latency = 1;
 128         driver->states[0].target_residency = 10000;
 129         driver->states[0].flags = CPUIDLE_FLAG_TIME_VALID;
 130         strcpy(driver->states[0].name, "WFI");
 131         strcpy(driver->states[0].desc, "Wait for interrupt");
 132
 133         /* Wait for interrupt and DDR self refresh state */
 134         driver->states[1].enter = davinci_enter_idle;
 135         driver->states[1].exit_latency = 10;
 136         driver->states[1].target_residency = 10000;
 137         driver->states[1].flags = CPUIDLE_FLAG_TIME_VALID;
 138         strcpy(driver->states[1].name, "DDR SR");
 139         strcpy(driver->states[1].desc, "WFI and DDR Self Refresh");
 140         if (pdata->ddr2_pdown)
 141                 davinci_states[1].flags |= DAVINCI_CPUIDLE_FLAGS_DDR2_PWDN;
 142         cpuidle_set_statedata(&device->states_usage[1], &davinci_states[1]);
 143
 144         device->state_count = DAVINCI_CPUIDLE_MAX_STATES;
 145         driver->state_count = DAVINCI_CPUIDLE_MAX_STATES;
 146
 147         ret = cpuidle_register_driver(&davinci_idle_driver);
 148         if (ret) {
 149                 dev_err(&pdev->dev, "failed to register driver\n");
 150                 return ret;
 151         }
 152
 153         ret = cpuidle_register_device(device);
 154         if (ret) {
 155                 dev_err(&pdev->dev, "failed to register device\n");
 156                 cpuidle_unregister_driver(&davinci_idle_driver);
 157                 return ret;
 158         }
 159
 160         return 0;
 161 }
 162
 163 static struct platform_driver davinci_cpuidle_driver = {
 164         .driver = {
 165                 .name   = "cpuidle-davinci",
 166                 .owner  = THIS_MODULE,
 167         },
 168 };
 169
 170 static int __init davinci_cpuidle_init(void)
 171 {
 172         return platform_driver_probe(&davinci_cpuidle_driver,
 173                                                 davinci_cpuidle_probe);
 174 }
 175 device_initcall(davinci_cpuidle_init);
 176