drivers/base/power/runtime.c

   1 /*
   2  * drivers/base/power/runtime.c - Handling dynamic device power management.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Open Source Development Lab
   6  *
   7  */
   8
   9 #include <linux/device.h>
  10 #include "power.h"
  11
  12
  13 static void runtime_resume(struct device * dev)
  14 {
  15         dev_dbg(dev, "resuming\n");
  16         if (!dev->power.power_state)
  17                 return;
  18         if (!resume_device(dev))
  19                 dev->power.power_state = 0;
  20 }
  21
  22
  23 /**
  24  *      dpm_runtime_resume - Power one device back on.
  25  *      @dev:   Device.
  26  *
  27  *      Bring one device back to the on state by first powering it
  28  *      on, then restoring state. We only operate on devices that aren't
  29  *      already on.
  30  *      FIXME: We need to handle devices that are in an unknown state.
  31  */
  32
  33 void dpm_runtime_resume(struct device * dev)
  34 {
  35         down(&dpm_sem);
  36         runtime_resume(dev);
  37         up(&dpm_sem);
  38 }
  39
  40
  41 /**
  42  *      dpm_runtime_suspend - Put one device in low-power state.
  43  *      @dev:   Device.
  44  *      @state: State to enter.
  45  */
  46
  47 int dpm_runtime_suspend(struct device * dev, pm_message_t state)
  48 {
  49         int error = 0;
  50
  51         down(&dpm_sem);
  52         if (dev->power.power_state == state)
  53                 goto Done;
  54
  55         if (dev->power.power_state)
  56                 runtime_resume(dev);
  57
  58         if (!(error = suspend_device(dev, state)))
  59                 dev->power.power_state = state;
  60  Done:
  61         up(&dpm_sem);
  62         return error;
  63 }
  64
  65
  66 /**
  67  *      dpm_set_power_state - Update power_state field.
  68  *      @dev:   Device.
  69  *      @state: Power state device is in.
  70  *
  71  *      This is an update mechanism for drivers to notify the core
  72  *      what power state a device is in. Device probing code may not
  73  *      always be able to tell, but we need accurate information to
  74  *      work reliably.
  75  */
  76 void dpm_set_power_state(struct device * dev, pm_message_t state)
  77 {
  78         down(&dpm_sem);
  79         dev->power.power_state = state;
  80         up(&dpm_sem);
  81 }