arch/arm/mach-davinci/cpuidle.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * CPU idle for DaVinci SoCs
   4  *
   5  * Copyright (C) 2009 Texas Instruments Incorporated. https://www.ti.com/
   6  *
   7  * Derived from Marvell Kirkwood CPU idle code
   8  * (arch/arm/mach-kirkwood/cpuidle.c)
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/cpuidle.h>
  15 #include <linux/io.h>
  16 #include <linux/export.h>
  17 #include <asm/cpuidle.h>
  18
  19 #include "cpuidle.h"
  20 #include "ddr2.h"
  21
  22 #define DAVINCI_CPUIDLE_MAX_STATES      2
  23
  24 static void __iomem *ddr2_reg_base;
  25 static bool ddr2_pdown;
  26
  27 static void davinci_save_ddr_power(int enter, bool pdown)
  28 {
  29         u32 val;
  30
  31         val = __raw_readl(ddr2_reg_base + DDR2_SDRCR_OFFSET);
  32
  33         if (enter) {
  34                 if (pdown)
  35                         val |= DDR2_SRPD_BIT;
  36                 else
  37                         val &= ~DDR2_SRPD_BIT;
  38                 val |= DDR2_LPMODEN_BIT;
  39         } else {
  40                 val &= ~(DDR2_SRPD_BIT | DDR2_LPMODEN_BIT);
  41         }
  42
  43         __raw_writel(val, ddr2_reg_base + DDR2_SDRCR_OFFSET);
  44 }
  45
  46 /* Actual code that puts the SoC in different idle states */
  47 static int davinci_enter_idle(struct cpuidle_device *dev,
  48                               struct cpuidle_driver *drv, int index)
  49 {
  50         davinci_save_ddr_power(1, ddr2_pdown);
  51         cpu_do_idle();
  52         davinci_save_ddr_power(0, ddr2_pdown);
  53
  54         return index;
  55 }
  56
  57 static struct cpuidle_driver davinci_idle_driver = {
  58         .name                   = "cpuidle-davinci",
  59         .owner                  = THIS_MODULE,
  60         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  61         .states[1]              = {
  62                 .enter                  = davinci_enter_idle,
  63                 .exit_latency           = 10,
  64                 .target_residency       = 10000,
  65                 .name                   = "DDR SR",
  66                 .desc                   = "WFI and DDR Self Refresh",
  67         },
  68         .state_count = DAVINCI_CPUIDLE_MAX_STATES,
  69 };
  70
  71 static int __init davinci_cpuidle_probe(struct platform_device *pdev)
  72 {
  73         struct davinci_cpuidle_config *pdata = pdev->dev.platform_data;
  74
  75         if (!pdata) {
  76                 dev_err(&pdev->dev, "cannot get platform data\n");
  77                 return -ENOENT;
  78         }
  79
  80         ddr2_reg_base = pdata->ddr2_ctlr_base;
  81
  82         ddr2_pdown = pdata->ddr2_pdown;
  83
  84         return cpuidle_register(&davinci_idle_driver, NULL);
  85 }
  86
  87 static struct platform_driver davinci_cpuidle_driver = {
  88         .driver = {
  89                 .name   = "cpuidle-davinci",
  90         },
  91 };
  92
  93 static int __init davinci_cpuidle_init(void)
  94 {
  95         return platform_driver_probe(&davinci_cpuidle_driver,
  96                                                 davinci_cpuidle_probe);
  97 }
  98 device_initcall(davinci_cpuidle_init);
  99