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->type && dev->type->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->type->suspend(dev, state);
  90                 suspend_report_result(dev->type->suspend, error);
  91         }
  92
  93         if (!error && dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
  94                 dev_dbg(dev, "%s%s\n",
  95                         suspend_verb(state.event),
  96                         ((state.event == PM_EVENT_SUSPEND)
  97                                         && device_may_wakeup(dev))
  98                                 ? ", may wakeup"
  99                                 : ""
 100                         );
 101                 error = dev->bus->suspend(dev, state);
 102                 suspend_report_result(dev->bus->suspend, error);
 103         }
 104         up(&dev->sem);
 105         return error;
 106 }
 107
 108
 109 /*
 110  * This is called with interrupts off, only a single CPU
 111  * running. We can't do down() on a semaphore (and we don't
 112  * need the protection)
 113  */
 114 static int suspend_device_late(struct device *dev, pm_message_t state)
 115 {
 116         int error = 0;
 117
 118         if (dev->bus && dev->bus->suspend_late && !dev->power.power_state.event) {
 119                 dev_dbg(dev, "LATE %s%s\n",
 120                         suspend_verb(state.event),
 121                         ((state.event == PM_EVENT_SUSPEND)
 122                                         && device_may_wakeup(dev))
 123                                 ? ", may wakeup"
 124                                 : ""
 125                         );
 126                 error = dev->bus->suspend_late(dev, state);
 127                 suspend_report_result(dev->bus->suspend_late, error);
 128         }
 129         return error;
 130 }
 131
 132 /**
 133  *      device_suspend - Save state and stop all devices in system.
 134  *      @state:         Power state to put each device in.
 135  *
 136  *      Walk the dpm_active list, call ->suspend() for each device, and move
 137  *      it to the dpm_off list.
 138  *
 139  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 140  *      that the device would be called again with interrupts disabled.
 141  *      These days, we use the "suspend_late()" callback for that, so we
 142  *      print a warning and consider it an error).
 143  *
 144  *      If we get a different error, try and back out.
 145  *
 146  *      If we hit a failure with any of the devices, call device_resume()
 147  *      above to bring the suspended devices back to life.
 148  *
 149  */
 150
 151 int device_suspend(pm_message_t state)
 152 {
 153         int error = 0;
 154
 155         might_sleep();
 156         down(&dpm_sem);
 157         down(&dpm_list_sem);
 158         while (!list_empty(&dpm_active) && error == 0) {
 159                 struct list_head * entry = dpm_active.prev;
 160                 struct device * dev = to_device(entry);
 161
 162                 get_device(dev);
 163                 up(&dpm_list_sem);
 164
 165                 error = suspend_device(dev, state);
 166
 167                 down(&dpm_list_sem);
 168
 169                 /* Check if the device got removed */
 170                 if (!list_empty(&dev->power.entry)) {
 171                         /* Move it to the dpm_off list */
 172                         if (!error)
 173                                 list_move(&dev->power.entry, &dpm_off);
 174                 }
 175                 if (error)
 176                         printk(KERN_ERR "Could not suspend device %s: "
 177                                 "error %d%s\n",
 178                                 kobject_name(&dev->kobj), error,
 179                                 error == -EAGAIN ? " (please convert to suspend_late)" : "");
 180                 put_device(dev);
 181         }
 182         up(&dpm_list_sem);
 183         if (error)
 184                 dpm_resume();
 185
 186         up(&dpm_sem);
 187         return error;
 188 }
 189
 190 EXPORT_SYMBOL_GPL(device_suspend);
 191
 192 /**
 193  *      device_power_down - Shut down special devices.
 194  *      @state:         Power state to enter.
 195  *
 196  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 197  *      couldn't power down the device with interrupts enabled. When we're
 198  *      done, power down system devices.
 199  */
 200
 201 int device_power_down(pm_message_t state)
 202 {
 203         int error = 0;
 204         struct device * dev;
 205
 206         while (!list_empty(&dpm_off)) {
 207                 struct list_head * entry = dpm_off.prev;
 208
 209                 dev = to_device(entry);
 210                 error = suspend_device_late(dev, state);
 211                 if (error)
 212                         goto Error;
 213                 list_move(&dev->power.entry, &dpm_off_irq);
 214         }
 215
 216         error = sysdev_suspend(state);
 217  Done:
 218         return error;
 219  Error:
 220         printk(KERN_ERR "Could not power down device %s: "
 221                 "error %d\n", kobject_name(&dev->kobj), error);
 222         dpm_power_up();
 223         goto Done;
 224 }
 225
 226 EXPORT_SYMBOL_GPL(device_power_down);
 227
 228 void __suspend_report_result(const char *function, void *fn, int ret)
 229 {
 230         if (ret) {
 231                 printk(KERN_ERR "%s(): ", function);
 232                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 233                 printk("%d\n", ret);
 234         }
 235 }
 236 EXPORT_SYMBOL_GPL(__suspend_report_result);