drivers/cpuidle/cpuidle-at91.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * based on arch/arm/mach-kirkwood/cpuidle.c
   4  *
   5  * CPU idle support for AT91 SoC
   6  *
   7  * The cpu idle uses wait-for-interrupt and RAM self refresh in order
   8  * to implement two idle states -
   9  * #1 wait-for-interrupt
  10  * #2 wait-for-interrupt and RAM self refresh
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/platform_device.h>
  16 #include <linux/cpuidle.h>
  17 #include <linux/io.h>
  18 #include <linux/export.h>
  19 #include <asm/cpuidle.h>
  20
  21 #define AT91_MAX_STATES 2
  22
  23 static void (*at91_standby)(void);
  24
  25 /* Actual code that puts the SoC in different idle states */
  26 static int at91_enter_idle(struct cpuidle_device *dev,
  27                         struct cpuidle_driver *drv,
  28                                int index)
  29 {
  30         at91_standby();
  31         return index;
  32 }
  33
  34 static struct cpuidle_driver at91_idle_driver = {
  35         .name                   = "at91_idle",
  36         .owner                  = THIS_MODULE,
  37         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  38         .states[1]              = {
  39                 .enter                  = at91_enter_idle,
  40                 .exit_latency           = 10,
  41                 .target_residency       = 10000,
  42                 .name                   = "RAM_SR",
  43                 .desc                   = "WFI and DDR Self Refresh",
  44         },
  45         .state_count = AT91_MAX_STATES,
  46 };
  47
  48 /* Initialize CPU idle by registering the idle states */
  49 static int at91_cpuidle_probe(struct platform_device *dev)
  50 {
  51         at91_standby = (void *)(dev->dev.platform_data);
  52
  53         return cpuidle_register(&at91_idle_driver, NULL);
  54 }
  55
  56 static struct platform_driver at91_cpuidle_driver = {
  57         .driver = {
  58                 .name = "cpuidle-at91",
  59         },
  60         .probe = at91_cpuidle_probe,
  61 };
  62 builtin_platform_driver(at91_cpuidle_driver);