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 void __iomem *ddr2_reg_base;
  29 static bool ddr2_pdown;
  30
  31 static void davinci_save_ddr_power(int enter, bool pdown)
  32 {
  33         u32 val;
  34
  35         val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
  36
  37         if (enter) {
  38                 if (pdown)
  39                         val |= DDR2_SRPD_BIT;
  40                 else
  41                         val &= ~DDR2_SRPD_BIT;
  42                 val |= DDR2_LPMODEN_BIT;
  43         } else {
  44                 val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
  45         }
  46
  47         __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
  48 }
  49
  50 /* Actual code that puts the SoC in different idle states */
  51 static int davinci_enter_idle(struct cpuidle_device *dev,
  52                               struct cpuidle_driver *drv, int index)
  53 {
  54         davinci_save_ddr_power(1, ddr2_pdown);
  55         cpu_do_idle();
  56         davinci_save_ddr_power(0, ddr2_pdown);
  57
  58         return index;
  59 }
  60
  61 static struct cpuidle_driver davinci_idle_driver = {
  62         .name                   = "cpuidle-davinci",
  63         .owner                  = THIS_MODULE,
  64         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  65         .states[1]              = {
  66                 .enter                  = davinci_enter_idle,
  67                 .exit_latency           = 10,
  68                 .target_residency       = 10000,
  69                 .name                   = "DDR SR",
  70                 .desc                   = "WFI and DDR Self Refresh",
  71         },
  72         .state_count = DAVINCI_CPUIDLE_MAX_STATES,
  73 };
  74
  75 static int __init davinci_cpuidle_probe(struct platform_device *pdev)
  76 {
  77         struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
  78
  79         if (!pdata) {
  80                 dev_err(&pdev->dev, "cannot get platform data\n");
  81                 return -ENOENT;
  82         }
  83
  84         ddr2_reg_base = pdata->ddr2_ctlr_base;
  85
  86         ddr2_pdown = pdata->ddr2_pdown;
  87
  88         return cpuidle_register(&davinci_idle_driver, NULL);
  89 }
  90
  91 static struct platform_driver davinci_cpuidle_driver = {
  92         .driver = {
  93                 .name   = "cpuidle-davinci",
  94         },
  95 };
  96
  97 static int __init davinci_cpuidle_init(void)
  98 {
  99         return platform_driver_probe(&davinci_cpuidle_driver,
 100                                                 davinci_cpuidle_probe);
 101 }
 102 device_initcall(davinci_cpuidle_init);
 103