drivers/base/power/suspend.c

   1 /*
   2  * suspend.c - Functions for putting devices to sleep.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Open Source Development Labs
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/device.h>
  12 #include "power.h"
  13
  14 extern int sysdev_suspend(pm_message_t state);
  15
  16 /*
  17  * The entries in the dpm_active list are in a depth first order, simply
  18  * because children are guaranteed to be discovered after parents, and
  19  * are inserted at the back of the list on discovery.
  20  *
  21  * All list on the suspend path are done in reverse order, so we operate
  22  * on the leaves of the device tree (or forests, depending on how you want
  23  * to look at it ;) first. As nodes are removed from the back of the list,
  24  * they are inserted into the front of their destintation lists.
  25  *
  26  * Things are the reverse on the resume path - iterations are done in
  27  * forward order, and nodes are inserted at the back of their destination
  28  * lists. This way, the ancestors will be accessed before their descendents.
  29  */
  30
  31
  32 /**
  33  *      suspend_device - Save state of one device.
  34  *      @dev:   Device.
  35  *      @state: Power state device is entering.
  36  */
  37
  38 int suspend_device(struct device * dev, pm_message_t state)
  39 {
  40         int error = 0;
  41
  42         dev_dbg(dev, "suspending\n");
  43
  44         dev->power.prev_state = dev->power.power_state;
  45
  46         if (dev->bus && dev->bus->suspend && !dev->power.power_state)
  47                 error = dev->bus->suspend(dev, state);
  48
  49         return error;
  50 }
  51
  52
  53 /**
  54  *      device_suspend - Save state and stop all devices in system.
  55  *      @state:         Power state to put each device in.
  56  *
  57  *      Walk the dpm_active list, call ->suspend() for each device, and move
  58  *      it to dpm_off.
  59  *      Check the return value for each. If it returns 0, then we move the
  60  *      the device to the dpm_off list. If it returns -EAGAIN, we move it to
  61  *      the dpm_off_irq list. If we get a different error, try and back out.
  62  *
  63  *      If we hit a failure with any of the devices, call device_resume()
  64  *      above to bring the suspended devices back to life.
  65  *
  66  */
  67
  68 int device_suspend(pm_message_t state)
  69 {
  70         int error = 0;
  71
  72         down(&dpm_sem);
  73         down(&dpm_list_sem);
  74         while (!list_empty(&dpm_active) && error == 0) {
  75                 struct list_head * entry = dpm_active.prev;
  76                 struct device * dev = to_device(entry);
  77
  78                 get_device(dev);
  79                 up(&dpm_list_sem);
  80
  81                 error = suspend_device(dev, state);
  82
  83                 down(&dpm_list_sem);
  84
  85                 /* Check if the device got removed */
  86                 if (!list_empty(&dev->power.entry)) {
  87                         /* Move it to the dpm_off or dpm_off_irq list */
  88                         if (!error) {
  89                                 list_del(&dev->power.entry);
  90                                 list_add(&dev->power.entry, &dpm_off);
  91                         } else if (error == -EAGAIN) {
  92                                 list_del(&dev->power.entry);
  93                                 list_add(&dev->power.entry, &dpm_off_irq);
  94                                 error = 0;
  95                         }
  96                 }
  97                 if (error)
  98                         printk(KERN_ERR "Could not suspend device %s: "
  99                                 "error %d\n", kobject_name(&dev->kobj), error);
 100                 put_device(dev);
 101         }
 102         up(&dpm_list_sem);
 103         if (error)
 104                 dpm_resume();
 105         up(&dpm_sem);
 106         return error;
 107 }
 108
 109 EXPORT_SYMBOL_GPL(device_suspend);
 110
 111
 112 /**
 113  *      device_power_down - Shut down special devices.
 114  *      @state:         Power state to enter.
 115  *
 116  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 117  *      couldn't power down the device with interrupts enabled. When we're
 118  *      done, power down system devices.
 119  */
 120
 121 int device_power_down(pm_message_t state)
 122 {
 123         int error = 0;
 124         struct device * dev;
 125
 126         list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
 127                 if ((error = suspend_device(dev, state)))
 128                         break;
 129         }
 130         if (error)
 131                 goto Error;
 132         if ((error = sysdev_suspend(state)))
 133                 goto Error;
 134  Done:
 135         return error;
 136  Error:
 137         printk(KERN_ERR "Could not power down device %s: "
 138                 "error %d\n", kobject_name(&dev->kobj), error);
 139         dpm_power_up();
 140         goto Done;
 141 }
 142
 143 EXPORT_SYMBOL_GPL(device_power_down);
 144