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         if (dev->power.power_state) {
  43                 dev_dbg(dev, "PM: suspend %d-->%d\n",
  44                         dev->power.power_state, state);
  45         }
  46         if (dev->power.pm_parent
  47                         && dev->power.pm_parent->power.power_state) {
  48                 dev_err(dev,
  49                         "PM: suspend %d->%d, parent %s already %d\n",
  50                         dev->power.power_state, state,
  51                         dev->power.pm_parent->bus_id,
  52                         dev->power.pm_parent->power.power_state);
  53         }
  54
  55         dev->power.prev_state = dev->power.power_state;
  56
  57         if (dev->bus && dev->bus->suspend && !dev->power.power_state) {
  58                 dev_dbg(dev, "suspending\n");
  59                 error = dev->bus->suspend(dev, state);
  60         }
  61
  62         return error;
  63 }
  64
  65
  66 /**
  67  *      device_suspend - Save state and stop all devices in system.
  68  *      @state:         Power state to put each device in.
  69  *
  70  *      Walk the dpm_active list, call ->suspend() for each device, and move
  71  *      it to dpm_off.
  72  *      Check the return value for each. If it returns 0, then we move the
  73  *      the device to the dpm_off list. If it returns -EAGAIN, we move it to
  74  *      the dpm_off_irq list. If we get a different error, try and back out.
  75  *
  76  *      If we hit a failure with any of the devices, call device_resume()
  77  *      above to bring the suspended devices back to life.
  78  *
  79  */
  80
  81 int device_suspend(pm_message_t state)
  82 {
  83         int error = 0;
  84
  85         down(&dpm_sem);
  86         down(&dpm_list_sem);
  87         while (!list_empty(&dpm_active) && error == 0) {
  88                 struct list_head * entry = dpm_active.prev;
  89                 struct device * dev = to_device(entry);
  90
  91                 get_device(dev);
  92                 up(&dpm_list_sem);
  93
  94                 error = suspend_device(dev, state);
  95
  96                 down(&dpm_list_sem);
  97
  98                 /* Check if the device got removed */
  99                 if (!list_empty(&dev->power.entry)) {
 100                         /* Move it to the dpm_off or dpm_off_irq list */
 101                         if (!error) {
 102                                 list_del(&dev->power.entry);
 103                                 list_add(&dev->power.entry, &dpm_off);
 104                         } else if (error == -EAGAIN) {
 105                                 list_del(&dev->power.entry);
 106                                 list_add(&dev->power.entry, &dpm_off_irq);
 107                                 error = 0;
 108                         }
 109                 }
 110                 if (error)
 111                         printk(KERN_ERR "Could not suspend device %s: "
 112                                 "error %d\n", kobject_name(&dev->kobj), error);
 113                 put_device(dev);
 114         }
 115         up(&dpm_list_sem);
 116         if (error)
 117                 dpm_resume();
 118         up(&dpm_sem);
 119         return error;
 120 }
 121
 122 EXPORT_SYMBOL_GPL(device_suspend);
 123
 124
 125 /**
 126  *      device_power_down - Shut down special devices.
 127  *      @state:         Power state to enter.
 128  *
 129  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 130  *      couldn't power down the device with interrupts enabled. When we're
 131  *      done, power down system devices.
 132  */
 133
 134 int device_power_down(pm_message_t state)
 135 {
 136         int error = 0;
 137         struct device * dev;
 138
 139         list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
 140                 if ((error = suspend_device(dev, state)))
 141                         break;
 142         }
 143         if (error)
 144                 goto Error;
 145         if ((error = sysdev_suspend(state)))
 146                 goto Error;
 147  Done:
 148         return error;
 149  Error:
 150         printk(KERN_ERR "Could not power down device %s: "
 151                 "error %d\n", kobject_name(&dev->kobj), error);
 152         dpm_power_up();
 153         goto Done;
 154 }
 155
 156 EXPORT_SYMBOL_GPL(device_power_down);
 157