arch/arm/mach-kirkwood/cpuidle.c

   1 /*
   2  * arch/arm/mach-kirkwood/cpuidle.c
   3  *
   4  * CPU idle Marvell Kirkwood SoCs
   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 DDR self refresh in order
  11  * to implement two idle states -
  12  * #1 wait-for-interrupt
  13  * #2 wait-for-interrupt and DDR 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/kirkwood.h>
  25
  26 #define KIRKWOOD_MAX_STATES     2
  27
  28 /* Actual code that puts the SoC in different idle states */
  29 static int kirkwood_enter_idle(struct cpuidle_device *dev,
  30                                 struct cpuidle_driver *drv,
  31                                int index)
  32 {
  33         writel(0x7, DDR_OPERATION_BASE);
  34         cpu_do_idle();
  35
  36         return index;
  37 }
  38
  39 static struct cpuidle_driver kirkwood_idle_driver = {
  40         .name                   = "kirkwood_idle",
  41         .owner                  = THIS_MODULE,
  42         .en_core_tk_irqen       = 1,
  43         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  44         .states[1]              = {
  45                 .enter                  = kirkwood_enter_idle,
  46                 .exit_latency           = 10,
  47                 .target_residency       = 100000,
  48                 .flags                  = CPUIDLE_FLAG_TIME_VALID,
  49                 .name                   = "DDR SR",
  50                 .desc                   = "WFI and DDR Self Refresh",
  51         },
  52         .state_count = KIRKWOOD_MAX_STATES,
  53 };
  54
  55 static DEFINE_PER_CPU(struct cpuidle_device, kirkwood_cpuidle_device);
  56
  57 /* Initialize CPU idle by registering the idle states */
  58 static int kirkwood_init_cpuidle(void)
  59 {
  60         struct cpuidle_device *device;
  61
  62         device = &per_cpu(kirkwood_cpuidle_device, smp_processor_id());
  63         device->state_count = KIRKWOOD_MAX_STATES;
  64
  65         cpuidle_register_driver(&kirkwood_idle_driver);
  66         if (cpuidle_register_device(device)) {
  67                 pr_err("kirkwood_init_cpuidle: Failed registering\n");
  68                 return -EIO;
  69         }
  70         return 0;
  71 }
  72
  73 device_initcall(kirkwood_init_cpuidle);