arch/arm/mach-at91/cpuidle.c

   1 /*
   2  * based on arch/arm/mach-kirkwood/cpuidle.c
   3  *
   4  * CPU idle support for AT91 SoC
   5  *
   6  * This file is licensed under the terms of the GNU General Public
   7  * License version 2.  This program is licensed "as is" without any
   8  * warranty of any kind, whether express or implied.
   9  *
  10  * The cpu idle uses wait-for-interrupt and RAM self refresh in order
  11  * to implement two idle states -
  12  * #1 wait-for-interrupt
  13  * #2 wait-for-interrupt and RAM self refresh
  14  */
  15
  16 #include <linux/kernel.h>
  17 #include <linux/init.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/cpuidle.h>
  20 #include <linux/io.h>
  21 #include <linux/export.h>
  22 #include <asm/proc-fns.h>
  23 #include <asm/cpuidle.h>
  24 #include <mach/cpu.h>
  25
  26 #include "pm.h"
  27
  28 #define AT91_MAX_STATES 2
  29
  30 static DEFINE_PER_CPU(struct cpuidle_device, at91_cpuidle_device);
  31
  32 /* Actual code that puts the SoC in different idle states */
  33 static int at91_enter_idle(struct cpuidle_device *dev,
  34                         struct cpuidle_driver *drv,
  35                                int index)
  36 {
  37         if (cpu_is_at91rm9200())
  38                 at91rm9200_standby();
  39         else if (cpu_is_at91sam9g45())
  40                 at91sam9g45_standby();
  41         else
  42                 at91sam9_standby();
  43
  44         return index;
  45 }
  46
  47 static struct cpuidle_driver at91_idle_driver = {
  48         .name                   = "at91_idle",
  49         .owner                  = THIS_MODULE,
  50         .en_core_tk_irqen       = 1,
  51         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  52         .states[1]              = {
  53                 .enter                  = at91_enter_idle,
  54                 .exit_latency           = 10,
  55                 .target_residency       = 100000,
  56                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  57                 .name                   = "RAM_SR",
  58                 .desc                   = "WFI and DDR Self Refresh",
  59         },
  60         .state_count = AT91_MAX_STATES,
  61 };
  62
  63 /* Initialize CPU idle by registering the idle states */
  64 static int at91_init_cpuidle(void)
  65 {
  66         struct cpuidle_device *device;
  67
  68         device = &per_cpu(at91_cpuidle_device, smp_processor_id());
  69         device->state_count = AT91_MAX_STATES;
  70
  71         cpuidle_register_driver(&at91_idle_driver);
  72
  73         if (cpuidle_register_device(device)) {
  74                 printk(KERN_ERR "at91_init_cpuidle: Failed registering\n");
  75                 return -EIO;
  76         }
  77         return 0;
  78 }
  79
  80 device_initcall(at91_init_cpuidle);