arch/arm/mach-exynos4/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
  16 #include <asm/proc-fns.h>
  17
  18 static int exynos4_enter_idle(struct cpuidle_device *dev,
  19                               struct cpuidle_state *state);
  20
  21 static struct cpuidle_state exynos4_cpuidle_set[] = {
  22         [0] = {
  23                 .enter                  = exynos4_enter_idle,
  24                 .exit_latency           = 1,
  25                 .target_residency       = 100000,
  26                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  27                 .name                   = "IDLE",
  28                 .desc                   = "ARM clock gating(WFI)",
  29         },
  30 };
  31
  32 static DEFINE_PER_CPU(struct cpuidle_device, exynos4_cpuidle_device);
  33
  34 static struct cpuidle_driver exynos4_idle_driver = {
  35         .name           = "exynos4_idle",
  36         .owner          = THIS_MODULE,
  37 };
  38
  39 static int exynos4_enter_idle(struct cpuidle_device *dev,
  40                               struct cpuidle_state *state)
  41 {
  42         struct timeval before, after;
  43         int idle_time;
  44
  45         local_irq_disable();
  46         do_gettimeofday(&before);
  47
  48         cpu_do_idle();
  49
  50         do_gettimeofday(&after);
  51         local_irq_enable();
  52         idle_time = (after.tv_sec - before.tv_sec) * USEC_PER_SEC +
  53                     (after.tv_usec - before.tv_usec);
  54
  55         return idle_time;
  56 }
  57
  58 static int __init exynos4_init_cpuidle(void)
  59 {
  60         int i, max_cpuidle_state, cpu_id;
  61         struct cpuidle_device *device;
  62
  63         cpuidle_register_driver(&exynos4_idle_driver);
  64
  65         for_each_cpu(cpu_id, cpu_online_mask) {
  66                 device = &per_cpu(exynos4_cpuidle_device, cpu_id);
  67                 device->cpu = cpu_id;
  68
  69                 device->state_count = (sizeof(exynos4_cpuidle_set) /
  70                                                sizeof(struct cpuidle_state));
  71
  72                 max_cpuidle_state = device->state_count;
  73
  74                 for (i = 0; i < max_cpuidle_state; i++) {
  75                         memcpy(&device->states[i], &exynos4_cpuidle_set[i],
  76                                         sizeof(struct cpuidle_state));
  77                 }
  78
  79                 if (cpuidle_register_device(device)) {
  80                         printk(KERN_ERR "CPUidle register device failed\n,");
  81                         return -EIO;
  82                 }
  83         }
  84         return 0;
  85 }
  86 device_initcall(exynos4_init_cpuidle);