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 static void
  44 suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
  45 {
  46         dev_dbg(dev, "%s%s%s\n", info, suspend_verb(state.event),
  47                 ((state.event == PM_EVENT_SUSPEND) && device_may_wakeup(dev)) ?
  48                 ", may wakeup" : "");
  49 }
  50
  51 /**
  52  *      suspend_device - Save state of one device.
  53  *      @dev:   Device.
  54  *      @state: Power state device is entering.
  55  */
  56
  57 int suspend_device(struct device * dev, pm_message_t state)
  58 {
  59         int error = 0;
  60
  61         down(&dev->sem);
  62         if (dev->power.power_state.event) {
  63                 dev_dbg(dev, "PM: suspend %d-->%d\n",
  64                         dev->power.power_state.event, state.event);
  65         }
  66         if (dev->parent && dev->parent->power.power_state.event) {
  67                 dev_err(dev,
  68                         "PM: suspend %d->%d, parent %s already %d\n",
  69                         dev->power.power_state.event, state.event,
  70                         dev->parent->bus_id,
  71                         dev->parent->power.power_state.event);
  72         }
  73
  74         if (dev->class && dev->class->suspend) {
  75                 suspend_device_dbg(dev, state, "class ");
  76                 error = dev->class->suspend(dev, state);
  77                 suspend_report_result(dev->class->suspend, error);
  78         }
  79
  80         if (!error && dev->type && dev->type->suspend) {
  81                 suspend_device_dbg(dev, state, "type ");
  82                 error = dev->type->suspend(dev, state);
  83                 suspend_report_result(dev->type->suspend, error);
  84         }
  85
  86         if (!error && dev->bus && dev->bus->suspend) {
  87                 suspend_device_dbg(dev, state, "");
  88                 error = dev->bus->suspend(dev, state);
  89                 suspend_report_result(dev->bus->suspend, error);
  90         }
  91         up(&dev->sem);
  92         return error;
  93 }
  94
  95
  96 /*
  97  * This is called with interrupts off, only a single CPU
  98  * running. We can't acquire a mutex or semaphore (and we don't
  99  * need the protection)
 100  */
 101 static int suspend_device_late(struct device *dev, pm_message_t state)
 102 {
 103         int error = 0;
 104
 105         if (dev->bus && dev->bus->suspend_late) {
 106                 suspend_device_dbg(dev, state, "LATE ");
 107                 error = dev->bus->suspend_late(dev, state);
 108                 suspend_report_result(dev->bus->suspend_late, error);
 109         }
 110         return error;
 111 }
 112
 113 /**
 114  *      device_suspend - Save state and stop all devices in system.
 115  *      @state:         Power state to put each device in.
 116  *
 117  *      Walk the dpm_active list, call ->suspend() for each device, and move
 118  *      it to the dpm_off list.
 119  *
 120  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 121  *      that the device would be called again with interrupts disabled.
 122  *      These days, we use the "suspend_late()" callback for that, so we
 123  *      print a warning and consider it an error).
 124  *
 125  *      If we get a different error, try and back out.
 126  *
 127  *      If we hit a failure with any of the devices, call device_resume()
 128  *      above to bring the suspended devices back to life.
 129  *
 130  */
 131
 132 int device_suspend(pm_message_t state)
 133 {
 134         int error = 0;
 135
 136         might_sleep();
 137         mutex_lock(&dpm_mtx);
 138         mutex_lock(&dpm_list_mtx);
 139         while (!list_empty(&dpm_active) && error == 0) {
 140                 struct list_head * entry = dpm_active.prev;
 141                 struct device * dev = to_device(entry);
 142
 143                 get_device(dev);
 144                 mutex_unlock(&dpm_list_mtx);
 145
 146                 error = suspend_device(dev, state);
 147
 148                 mutex_lock(&dpm_list_mtx);
 149
 150                 /* Check if the device got removed */
 151                 if (!list_empty(&dev->power.entry)) {
 152                         /* Move it to the dpm_off list */
 153                         if (!error)
 154                                 list_move(&dev->power.entry, &dpm_off);
 155                 }
 156                 if (error)
 157                         printk(KERN_ERR "Could not suspend device %s: "
 158                                 "error %d%s\n",
 159                                 kobject_name(&dev->kobj), error,
 160                                 error == -EAGAIN ? " (please convert to suspend_late)" : "");
 161                 put_device(dev);
 162         }
 163         mutex_unlock(&dpm_list_mtx);
 164         if (error)
 165                 dpm_resume();
 166
 167         mutex_unlock(&dpm_mtx);
 168         return error;
 169 }
 170
 171 EXPORT_SYMBOL_GPL(device_suspend);
 172
 173 /**
 174  *      device_power_down - Shut down special devices.
 175  *      @state:         Power state to enter.
 176  *
 177  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 178  *      couldn't power down the device with interrupts enabled. When we're
 179  *      done, power down system devices.
 180  */
 181
 182 int device_power_down(pm_message_t state)
 183 {
 184         int error = 0;
 185         struct device * dev;
 186
 187         while (!list_empty(&dpm_off)) {
 188                 struct list_head * entry = dpm_off.prev;
 189
 190                 dev = to_device(entry);
 191                 error = suspend_device_late(dev, state);
 192                 if (error)
 193                         goto Error;
 194                 list_move(&dev->power.entry, &dpm_off_irq);
 195         }
 196
 197         error = sysdev_suspend(state);
 198  Done:
 199         return error;
 200  Error:
 201         printk(KERN_ERR "Could not power down device %s: "
 202                 "error %d\n", kobject_name(&dev->kobj), error);
 203         dpm_power_up();
 204         goto Done;
 205 }
 206
 207 EXPORT_SYMBOL_GPL(device_power_down);
 208
 209 void __suspend_report_result(const char *function, void *fn, int ret)
 210 {
 211         if (ret) {
 212                 printk(KERN_ERR "%s(): ", function);
 213                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 214                 printk("%d\n", ret);
 215         }
 216 }
 217 EXPORT_SYMBOL_GPL(__suspend_report_result);