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 <linux/kallsyms.h>
  13 #include <linux/pm.h>
  14 #include "../base.h"
  15 #include "power.h"
  16
  17 /*
  18  * The entries in the dpm_active list are in a depth first order, simply
  19  * because children are guaranteed to be discovered after parents, and
  20  * are inserted at the back of the list on discovery.
  21  *
  22  * All list on the suspend path are done in reverse order, so we operate
  23  * on the leaves of the device tree (or forests, depending on how you want
  24  * to look at it ;) first. As nodes are removed from the back of the list,
  25  * they are inserted into the front of their destintation lists.
  26  *
  27  * Things are the reverse on the resume path - iterations are done in
  28  * forward order, and nodes are inserted at the back of their destination
  29  * lists. This way, the ancestors will be accessed before their descendents.
  30  */
  31
  32 static inline char *suspend_verb(u32 event)
  33 {
  34         switch (event) {
  35         case PM_EVENT_SUSPEND:  return "suspend";
  36         case PM_EVENT_FREEZE:   return "freeze";
  37         case PM_EVENT_PRETHAW:  return "prethaw";
  38         default:                return "(unknown suspend event)";
  39         }
  40 }
  41
  42
  43 /**
  44  *      suspend_device - Save state of one device.
  45  *      @dev:   Device.
  46  *      @state: Power state device is entering.
  47  */
  48
  49 int suspend_device(struct device * dev, pm_message_t state)
  50 {
  51         int error = 0;
  52
  53         down(&dev->sem);
  54         if (dev->power.power_state.event) {
  55                 dev_dbg(dev, "PM: suspend %d-->%d\n",
  56                         dev->power.power_state.event, state.event);
  57         }
  58         if (dev->power.pm_parent
  59                         && dev->power.pm_parent->power.power_state.event) {
  60                 dev_err(dev,
  61                         "PM: suspend %d->%d, parent %s already %d\n",
  62                         dev->power.power_state.event, state.event,
  63                         dev->power.pm_parent->bus_id,
  64                         dev->power.pm_parent->power.power_state.event);
  65         }
  66
  67         dev->power.prev_state = dev->power.power_state;
  68
  69         if (dev->class && dev->class->suspend && !dev->power.power_state.event) {
  70                 dev_dbg(dev, "class %s%s\n",
  71                         suspend_verb(state.event),
  72                         ((state.event == PM_EVENT_SUSPEND)
  73                                         && device_may_wakeup(dev))
  74                                 ? ", may wakeup"
  75                                 : ""
  76                         );
  77                 error = dev->class->suspend(dev, state);
  78                 suspend_report_result(dev->class->suspend, error);
  79         }
  80
  81         if (!error && dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
  82                 dev_dbg(dev, "%s%s\n",
  83                         suspend_verb(state.event),
  84                         ((state.event == PM_EVENT_SUSPEND)
  85                                         && device_may_wakeup(dev))
  86                                 ? ", may wakeup"
  87                                 : ""
  88                         );
  89                 error = dev->bus->suspend(dev, state);
  90                 suspend_report_result(dev->bus->suspend, error);
  91         }
  92         up(&dev->sem);
  93         return error;
  94 }
  95
  96
  97 /*
  98  * This is called with interrupts off, only a single CPU
  99  * running. We can't do down() on a semaphore (and we don't
 100  * need the protection)
 101  */
 102 static int suspend_device_late(struct device *dev, pm_message_t state)
 103 {
 104         int error = 0;
 105
 106         if (dev->bus && dev->bus->suspend_late && !dev->power.power_state.event) {
 107                 dev_dbg(dev, "LATE %s%s\n",
 108                         suspend_verb(state.event),
 109                         ((state.event == PM_EVENT_SUSPEND)
 110                                         && device_may_wakeup(dev))
 111                                 ? ", may wakeup"
 112                                 : ""
 113                         );
 114                 error = dev->bus->suspend_late(dev, state);
 115                 suspend_report_result(dev->bus->suspend_late, error);
 116         }
 117         return error;
 118 }
 119
 120 /**
 121  *      device_suspend - Save state and stop all devices in system.
 122  *      @state:         Power state to put each device in.
 123  *
 124  *      Walk the dpm_active list, call ->suspend() for each device, and move
 125  *      it to the dpm_off list.
 126  *
 127  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 128  *      that the device would be called again with interrupts disabled.
 129  *      These days, we use the "suspend_late()" callback for that, so we
 130  *      print a warning and consider it an error).
 131  *
 132  *      If we get a different error, try and back out.
 133  *
 134  *      If we hit a failure with any of the devices, call device_resume()
 135  *      above to bring the suspended devices back to life.
 136  *
 137  */
 138
 139 int device_suspend(pm_message_t state)
 140 {
 141         int error = 0;
 142
 143         might_sleep();
 144         down(&dpm_sem);
 145         down(&dpm_list_sem);
 146         while (!list_empty(&dpm_active) && error == 0) {
 147                 struct list_head * entry = dpm_active.prev;
 148                 struct device * dev = to_device(entry);
 149
 150                 get_device(dev);
 151                 up(&dpm_list_sem);
 152
 153                 error = suspend_device(dev, state);
 154
 155                 down(&dpm_list_sem);
 156
 157                 /* Check if the device got removed */
 158                 if (!list_empty(&dev->power.entry)) {
 159                         /* Move it to the dpm_off list */
 160                         if (!error)
 161                                 list_move(&dev->power.entry, &dpm_off);
 162                 }
 163                 if (error)
 164                         printk(KERN_ERR "Could not suspend device %s: "
 165                                 "error %d%s\n",
 166                                 kobject_name(&dev->kobj), error,
 167                                 error == -EAGAIN ? " (please convert to suspend_late)" : "");
 168                 put_device(dev);
 169         }
 170         up(&dpm_list_sem);
 171         if (error)
 172                 dpm_resume();
 173
 174         up(&dpm_sem);
 175         return error;
 176 }
 177
 178 EXPORT_SYMBOL_GPL(device_suspend);
 179
 180 /**
 181  *      device_power_down - Shut down special devices.
 182  *      @state:         Power state to enter.
 183  *
 184  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 185  *      couldn't power down the device with interrupts enabled. When we're
 186  *      done, power down system devices.
 187  */
 188
 189 int device_power_down(pm_message_t state)
 190 {
 191         int error = 0;
 192         struct device * dev;
 193
 194         while (!list_empty(&dpm_off)) {
 195                 struct list_head * entry = dpm_off.prev;
 196
 197                 dev = to_device(entry);
 198                 error = suspend_device_late(dev, state);
 199                 if (error)
 200                         goto Error;
 201                 list_move(&dev->power.entry, &dpm_off_irq);
 202         }
 203
 204         error = sysdev_suspend(state);
 205  Done:
 206         return error;
 207  Error:
 208         printk(KERN_ERR "Could not power down device %s: "
 209                 "error %d\n", kobject_name(&dev->kobj), error);
 210         dpm_power_up();
 211         goto Done;
 212 }
 213
 214 EXPORT_SYMBOL_GPL(device_power_down);
 215
 216 void __suspend_report_result(const char *function, void *fn, int ret)
 217 {
 218         if (ret) {
 219                 printk(KERN_ERR "%s(): ", function);
 220                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 221                 printk("%d\n", ret);
 222         }
 223 }
 224 EXPORT_SYMBOL_GPL(__suspend_report_result);