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 <linux/export.h>
  20 #include <asm/proc-fns.h>
  21 #include <asm/cpuidle.h>
  22
  23 #include <mach/cpuidle.h>
  24 #include <mach/ddr2.h>
  25
  26 #define DAVINCI_CPUIDLE_MAX_STATES      2
  27
  28 static DEFINE_PER_CPU(struct cpuidle_device, davinci_cpuidle_device);
  29 static void __iomem *ddr2_reg_base;
  30 static bool ddr2_pdown;
  31
  32 static void davinci_save_ddr_power(int enter, bool pdown)
  33 {
  34         u32 val;
  35
  36         val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
  37
  38         if (enter) {
  39                 if (pdown)
  40                         val |= DDR2_SRPD_BIT;
  41                 else
  42                         val &= ~DDR2_SRPD_BIT;
  43                 val |= DDR2_LPMODEN_BIT;
  44         } else {
  45                 val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
  46         }
  47
  48         __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
  49 }
  50
  51 /* Actual code that puts the SoC in different idle states */
  52 static int davinci_enter_idle(struct cpuidle_device *dev,
  53                                 struct cpuidle_driver *drv,
  54                                                 int index)
  55 {
  56         davinci_save_ddr_power(1, ddr2_pdown);
  57
  58         index = cpuidle_wrap_enter(dev, drv, index,
  59                                 arm_cpuidle_simple_enter);
  60
  61         davinci_save_ddr_power(0, ddr2_pdown);
  62
  63         return index;
  64 }
  65
  66 static struct cpuidle_driver davinci_idle_driver = {
  67         .name                   = "cpuidle-davinci",
  68         .owner                  = THIS_MODULE,
  69         .en_core_tk_irqen       = 1,
  70         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  71         .states[1]              = {
  72                 .enter                  = davinci_enter_idle,
  73                 .exit_latency           = 10,
  74                 .target_residency       = 100000,
  75                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  76                 .name                   = "DDR SR",
  77                 .desc                   = "WFI and DDR Self Refresh",
  78         },
  79         .state_count = DAVINCI_CPUIDLE_MAX_STATES,
  80 };
  81
  82 static int __init davinci_cpuidle_probe(struct platform_device *pdev)
  83 {
  84         int ret;
  85         struct cpuidle_device *device;
  86         struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
  87
  88         device = &per_cpu(davinci_cpuidle_device, smp_processor_id());
  89
  90         if (!pdata) {
  91                 dev_err(&pdev->dev, "cannot get platform data\n");
  92                 return -ENOENT;
  93         }
  94
  95         ddr2_reg_base = pdata->ddr2_ctlr_base;
  96
  97         ddr2_pdown = pdata->ddr2_pdown;
  98
  99         ret = cpuidle_register_driver(&davinci_idle_driver);
 100         if (ret) {
 101                 dev_err(&pdev->dev, "failed to register driver\n");
 102                 return ret;
 103         }
 104
 105         ret = cpuidle_register_device(device);
 106         if (ret) {
 107                 dev_err(&pdev->dev, "failed to register device\n");
 108                 cpuidle_unregister_driver(&davinci_idle_driver);
 109                 return ret;
 110         }
 111
 112         return 0;
 113 }
 114
 115 static struct platform_driver davinci_cpuidle_driver = {
 116         .driver = {
 117                 .name   = "cpuidle-davinci",
 118                 .owner  = THIS_MODULE,
 119         },
 120 };
 121
 122 static int __init davinci_cpuidle_init(void)
 123 {
 124         return platform_driver_probe(&davinci_cpuidle_driver,
 125                                                 davinci_cpuidle_probe);
 126 }
 127 device_initcall(davinci_cpuidle_init);
 128