arch/arm/mach-exynos/cpuidle.c

   1 /* linux/arch/arm/mach-exynos4/cpuidle.c
   2  *
   3  * Copyright (c) 2011 Samsung Electronics Co., Ltd.
   4  *              http://www.samsung.com
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9 */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/init.h>
  13 #include <linux/cpuidle.h>
  14 #include <linux/io.h>
  15 #include <linux/export.h>
  16 #include <linux/time.h>
  17
  18 #include <asm/proc-fns.h>
  19
  20 static int exynos4_enter_idle(struct cpuidle_device *dev,
  21                         struct cpuidle_driver *drv,
  22                               int index);
  23
  24 static struct cpuidle_state exynos4_cpuidle_set[] = {
  25         [0] = {
  26                 .enter                  = exynos4_enter_idle,
  27                 .exit_latency           = 1,
  28                 .target_residency       = 100000,
  29                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  30                 .name                   = "IDLE",
  31                 .desc                   = "ARM clock gating(WFI)",
  32         },
  33 };
  34
  35 static DEFINE_PER_CPU(struct cpuidle_device, exynos4_cpuidle_device);
  36
  37 static struct cpuidle_driver exynos4_idle_driver = {
  38         .name           = "exynos4_idle",
  39         .owner          = THIS_MODULE,
  40 };
  41
  42 static int exynos4_enter_idle(struct cpuidle_device *dev,
  43                                 struct cpuidle_driver *drv,
  44                               int index)
  45 {
  46         struct timeval before, after;
  47         int idle_time;
  48
  49         local_irq_disable();
  50         do_gettimeofday(&before);
  51
  52         cpu_do_idle();
  53
  54         do_gettimeofday(&after);
  55         local_irq_enable();
  56         idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
  57                     (after.tv_usec - before.tv_usec);
  58
  59         dev->last_residency = idle_time;
  60         return index;
  61 }
  62
  63 static int __init exynos4_init_cpuidle(void)
  64 {
  65         int i, max_cpuidle_state, cpu_id;
  66         struct cpuidle_device *device;
  67         struct cpuidle_driver *drv = &exynos4_idle_driver;
  68
  69         /* Setup cpuidle driver */
  70         drv->state_count = (sizeof(exynos4_cpuidle_set) /
  71                                        sizeof(struct cpuidle_state));
  72         max_cpuidle_state = drv->state_count;
  73         for (i = 0; i < max_cpuidle_state; i++) {
  74                 memcpy(&drv->states[i], &exynos4_cpuidle_set[i],
  75                                 sizeof(struct cpuidle_state));
  76         }
  77         cpuidle_register_driver(&exynos4_idle_driver);
  78
  79         for_each_cpu(cpu_id, cpu_online_mask) {
  80                 device = &per_cpu(exynos4_cpuidle_device, cpu_id);
  81                 device->cpu = cpu_id;
  82
  83                 device->state_count = drv->state_count;
  84
  85                 if (cpuidle_register_device(device)) {
  86                         printk(KERN_ERR "CPUidle register device failed\n,");
  87                         return -EIO;
  88                 }
  89         }
  90         return 0;
  91 }
  92 device_initcall(exynos4_init_cpuidle);