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 /* Actual code that puts the SoC in different idle states */
  31 static int at91_enter_idle(struct cpuidle_device *dev,
  32                         struct cpuidle_driver *drv,
  33                                int index)
  34 {
  35         if (cpu_is_at91rm9200())
  36                 at91rm9200_standby();
  37         else if (cpu_is_at91sam9g45())
  38                 at91sam9g45_standby();
  39         else
  40                 at91sam9_standby();
  41
  42         return index;
  43 }
  44
  45 static struct cpuidle_driver at91_idle_driver = {
  46         .name                   = "at91_idle",
  47         .owner                  = THIS_MODULE,
  48         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  49         .states[1]              = {
  50                 .enter                  = at91_enter_idle,
  51                 .exit_latency           = 10,
  52                 .target_residency       = 100000,
  53                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  54                 .name                   = "RAM_SR",
  55                 .desc                   = "WFI and DDR Self Refresh",
  56         },
  57         .state_count = AT91_MAX_STATES,
  58 };
  59
  60 /* Initialize CPU idle by registering the idle states */
  61 static int __init at91_init_cpuidle(void)
  62 {
  63         return cpuidle_register(&at91_idle_driver, NULL);
  64 }
  65
  66 device_initcall(at91_init_cpuidle);