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 && !dev->power.power_state.event) {
  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             && !dev->power.power_state.event) {
  82                 suspend_device_dbg(dev, state, "type ");
  83                 error = dev->type->suspend(dev, state);
  84                 suspend_report_result(dev->type->suspend, error);
  85         }
  86
  87         if (!error && dev->bus && dev->bus->suspend
  88             && !dev->power.power_state.event) {
  89                 suspend_device_dbg(dev, state, "");
  90                 error = dev->bus->suspend(dev, state);
  91                 suspend_report_result(dev->bus->suspend, error);
  92         }
  93         up(&dev->sem);
  94         return error;
  95 }
  96
  97
  98 /*
  99  * This is called with interrupts off, only a single CPU
 100  * running. We can't acquire a mutex or semaphore (and we don't
 101  * need the protection)
 102  */
 103 static int suspend_device_late(struct device *dev, pm_message_t state)
 104 {
 105         int error = 0;
 106
 107         if (dev->bus && dev->bus->suspend_late
 108             && !dev->power.power_state.event) {
 109                 suspend_device_dbg(dev, state, "LATE ");
 110                 error = dev->bus->suspend_late(dev, state);
 111                 suspend_report_result(dev->bus->suspend_late, error);
 112         }
 113         return error;
 114 }
 115
 116 /**
 117  *      device_suspend - Save state and stop all devices in system.
 118  *      @state:         Power state to put each device in.
 119  *
 120  *      Walk the dpm_active list, call ->suspend() for each device, and move
 121  *      it to the dpm_off list.
 122  *
 123  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 124  *      that the device would be called again with interrupts disabled.
 125  *      These days, we use the "suspend_late()" callback for that, so we
 126  *      print a warning and consider it an error).
 127  *
 128  *      If we get a different error, try and back out.
 129  *
 130  *      If we hit a failure with any of the devices, call device_resume()
 131  *      above to bring the suspended devices back to life.
 132  *
 133  */
 134
 135 int device_suspend(pm_message_t state)
 136 {
 137         int error = 0;
 138
 139         might_sleep();
 140         mutex_lock(&dpm_mtx);
 141         mutex_lock(&dpm_list_mtx);
 142         while (!list_empty(&dpm_active) && error == 0) {
 143                 struct list_head * entry = dpm_active.prev;
 144                 struct device * dev = to_device(entry);
 145
 146                 get_device(dev);
 147                 mutex_unlock(&dpm_list_mtx);
 148
 149                 error = suspend_device(dev, state);
 150
 151                 mutex_lock(&dpm_list_mtx);
 152
 153                 /* Check if the device got removed */
 154                 if (!list_empty(&dev->power.entry)) {
 155                         /* Move it to the dpm_off list */
 156                         if (!error)
 157                                 list_move(&dev->power.entry, &dpm_off);
 158                 }
 159                 if (error)
 160                         printk(KERN_ERR "Could not suspend device %s: "
 161                                 "error %d%s\n",
 162                                 kobject_name(&dev->kobj), error,
 163                                 error == -EAGAIN ? " (please convert to suspend_late)" : "");
 164                 put_device(dev);
 165         }
 166         mutex_unlock(&dpm_list_mtx);
 167         if (error)
 168                 dpm_resume();
 169
 170         mutex_unlock(&dpm_mtx);
 171         return error;
 172 }
 173
 174 EXPORT_SYMBOL_GPL(device_suspend);
 175
 176 /**
 177  *      device_power_down - Shut down special devices.
 178  *      @state:         Power state to enter.
 179  *
 180  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 181  *      couldn't power down the device with interrupts enabled. When we're
 182  *      done, power down system devices.
 183  */
 184
 185 int device_power_down(pm_message_t state)
 186 {
 187         int error = 0;
 188         struct device * dev;
 189
 190         while (!list_empty(&dpm_off)) {
 191                 struct list_head * entry = dpm_off.prev;
 192
 193                 dev = to_device(entry);
 194                 error = suspend_device_late(dev, state);
 195                 if (error)
 196                         goto Error;
 197                 list_move(&dev->power.entry, &dpm_off_irq);
 198         }
 199
 200         error = sysdev_suspend(state);
 201  Done:
 202         return error;
 203  Error:
 204         printk(KERN_ERR "Could not power down device %s: "
 205                 "error %d\n", kobject_name(&dev->kobj), error);
 206         dpm_power_up();
 207         goto Done;
 208 }
 209
 210 EXPORT_SYMBOL_GPL(device_power_down);
 211
 212 void __suspend_report_result(const char *function, void *fn, int ret)
 213 {
 214         if (ret) {
 215                 printk(KERN_ERR "%s(): ", function);
 216                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 217                 printk("%d\n", ret);
 218         }
 219 }
 220 EXPORT_SYMBOL_GPL(__suspend_report_result);