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         down(&dev->sem);
  43         if (dev->power.power_state.event) {
  44                 dev_dbg(dev, "PM: suspend %d-->%d\n",
  45                         dev->power.power_state.event, state.event);
  46         }
  47         if (dev->power.pm_parent
  48                         && dev->power.pm_parent->power.power_state.event) {
  49                 dev_err(dev,
  50                         "PM: suspend %d->%d, parent %s already %d\n",
  51                         dev->power.power_state.event, state.event,
  52                         dev->power.pm_parent->bus_id,
  53                         dev->power.pm_parent->power.power_state.event);
  54         }
  55
  56         dev->power.prev_state = dev->power.power_state;
  57
  58         if (dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
  59                 dev_dbg(dev, "suspending\n");
  60                 error = dev->bus->suspend(dev, state);
  61         }
  62         up(&dev->sem);
  63         return error;
  64 }
  65
  66
  67 /**
  68  *      device_suspend - Save state and stop all devices in system.
  69  *      @state:         Power state to put each device in.
  70  *
  71  *      Walk the dpm_active list, call ->suspend() for each device, and move
  72  *      it to dpm_off.
  73  *      Check the return value for each. If it returns 0, then we move the
  74  *      the device to the dpm_off list. If it returns -EAGAIN, we move it to
  75  *      the dpm_off_irq list. If we get a different error, try and back out.
  76  *
  77  *      If we hit a failure with any of the devices, call device_resume()
  78  *      above to bring the suspended devices back to life.
  79  *
  80  */
  81
  82 int device_suspend(pm_message_t state)
  83 {
  84         int error = 0;
  85
  86         down(&dpm_sem);
  87         down(&dpm_list_sem);
  88         while (!list_empty(&dpm_active) && error == 0) {
  89                 struct list_head * entry = dpm_active.prev;
  90                 struct device * dev = to_device(entry);
  91
  92                 get_device(dev);
  93                 up(&dpm_list_sem);
  94
  95                 error = suspend_device(dev, state);
  96
  97                 down(&dpm_list_sem);
  98
  99                 /* Check if the device got removed */
 100                 if (!list_empty(&dev->power.entry)) {
 101                         /* Move it to the dpm_off or dpm_off_irq list */
 102                         if (!error) {
 103                                 list_del(&dev->power.entry);
 104                                 list_add(&dev->power.entry, &dpm_off);
 105                         } else if (error == -EAGAIN) {
 106                                 list_del(&dev->power.entry);
 107                                 list_add(&dev->power.entry, &dpm_off_irq);
 108                                 error = 0;
 109                         }
 110                 }
 111                 if (error)
 112                         printk(KERN_ERR "Could not suspend device %s: "
 113                                 "error %d\n", kobject_name(&dev->kobj), error);
 114                 put_device(dev);
 115         }
 116         up(&dpm_list_sem);
 117         if (error) {
 118                 /* we failed... before resuming, bring back devices from
 119                  * dpm_off_irq list back to main dpm_off list, we do want
 120                  * to call resume() on them, in case they partially suspended
 121                  * despite returning -EAGAIN
 122                  */
 123                 while (!list_empty(&dpm_off_irq)) {
 124                         struct list_head * entry = dpm_off_irq.next;
 125                         list_del(entry);
 126                         list_add(entry, &dpm_off);
 127                 }
 128                 dpm_resume();
 129         }
 130         up(&dpm_sem);
 131         return error;
 132 }
 133
 134 EXPORT_SYMBOL_GPL(device_suspend);
 135
 136
 137 /**
 138  *      device_power_down - Shut down special devices.
 139  *      @state:         Power state to enter.
 140  *
 141  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 142  *      couldn't power down the device with interrupts enabled. When we're
 143  *      done, power down system devices.
 144  */
 145
 146 int device_power_down(pm_message_t state)
 147 {
 148         int error = 0;
 149         struct device * dev;
 150
 151         list_for_each_entry_reverse(dev, &dpm_off_irq, power.entry) {
 152                 if ((error = suspend_device(dev, state)))
 153                         break;
 154         }
 155         if (error)
 156                 goto Error;
 157         if ((error = sysdev_suspend(state)))
 158                 goto Error;
 159  Done:
 160         return error;
 161  Error:
 162         printk(KERN_ERR "Could not power down device %s: "
 163                 "error %d\n", kobject_name(&dev->kobj), error);
 164         dpm_power_up();
 165         goto Done;
 166 }
 167
 168 EXPORT_SYMBOL_GPL(device_power_down);
 169