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         default:                return "(unknown suspend event)";
  38         }
  39 }
  40
  41
  42 /**
  43  *      suspend_device - Save state of one device.
  44  *      @dev:   Device.
  45  *      @state: Power state device is entering.
  46  */
  47
  48 int suspend_device(struct device * dev, pm_message_t state)
  49 {
  50         int error = 0;
  51
  52         down(&dev->sem);
  53         if (dev->power.power_state.event) {
  54                 dev_dbg(dev, "PM: suspend %d-->%d\n",
  55                         dev->power.power_state.event, state.event);
  56         }
  57         if (dev->power.pm_parent
  58                         && dev->power.pm_parent->power.power_state.event) {
  59                 dev_err(dev,
  60                         "PM: suspend %d->%d, parent %s already %d\n",
  61                         dev->power.power_state.event, state.event,
  62                         dev->power.pm_parent->bus_id,
  63                         dev->power.pm_parent->power.power_state.event);
  64         }
  65
  66         dev->power.prev_state = dev->power.power_state;
  67
  68         if (dev->class && dev->class->suspend && !dev->power.power_state.event) {
  69                 dev_dbg(dev, "class %s%s\n",
  70                         suspend_verb(state.event),
  71                         ((state.event == PM_EVENT_SUSPEND)
  72                                         && device_may_wakeup(dev))
  73                                 ? ", may wakeup"
  74                                 : ""
  75                         );
  76                 error = dev->class->suspend(dev, state);
  77                 suspend_report_result(dev->class->suspend, error);
  78         }
  79
  80         if (!error && dev->bus && dev->bus->suspend && !dev->power.power_state.event) {
  81                 dev_dbg(dev, "%s%s\n",
  82                         suspend_verb(state.event),
  83                         ((state.event == PM_EVENT_SUSPEND)
  84                                         && device_may_wakeup(dev))
  85                                 ? ", may wakeup"
  86                                 : ""
  87                         );
  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 do down() on a 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->power.power_state.event) {
 106                 dev_dbg(dev, "PM: suspend_late %d-->%d\n",
 107                         dev->power.power_state.event, state.event);
 108         }
 109
 110         if (dev->bus && dev->bus->suspend_late && !dev->power.power_state.event) {
 111                 dev_dbg(dev, "LATE %s%s\n",
 112                         suspend_verb(state.event),
 113                         ((state.event == PM_EVENT_SUSPEND)
 114                                         && device_may_wakeup(dev))
 115                                 ? ", may wakeup"
 116                                 : ""
 117                         );
 118                 error = dev->bus->suspend_late(dev, state);
 119                 suspend_report_result(dev->bus->suspend_late, error);
 120         }
 121         return error;
 122 }
 123
 124 /**
 125  *      device_prepare_suspend - save state and prepare to suspend
 126  *
 127  *      NOTE! Devices cannot detach at this point - not only do we
 128  *      hold the device list semaphores over the whole prepare, but
 129  *      the whole point is to do non-invasive preparatory work, not
 130  *      the actual suspend.
 131  */
 132 int device_prepare_suspend(pm_message_t state)
 133 {
 134         int error = 0;
 135         struct device * dev;
 136
 137         down(&dpm_sem);
 138         down(&dpm_list_sem);
 139         list_for_each_entry_reverse(dev, &dpm_active, power.entry) {
 140                 if (!dev->bus || !dev->bus->suspend_prepare)
 141                         continue;
 142                 error = dev->bus->suspend_prepare(dev, state);
 143                 if (error)
 144                         break;
 145         }
 146         up(&dpm_list_sem);
 147         up(&dpm_sem);
 148         return error;
 149 }
 150
 151 /**
 152  *      device_suspend - Save state and stop all devices in system.
 153  *      @state:         Power state to put each device in.
 154  *
 155  *      Walk the dpm_active list, call ->suspend() for each device, and move
 156  *      it to the dpm_off list.
 157  *
 158  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 159  *      that the device would be called again with interrupts disabled.
 160  *      These days, we use the "suspend_late()" callback for that, so we
 161  *      print a warning and consider it an error).
 162  *
 163  *      If we get a different error, try and back out.
 164  *
 165  *      If we hit a failure with any of the devices, call device_resume()
 166  *      above to bring the suspended devices back to life.
 167  *
 168  */
 169
 170 int device_suspend(pm_message_t state)
 171 {
 172         int error = 0;
 173
 174         down(&dpm_sem);
 175         down(&dpm_list_sem);
 176         while (!list_empty(&dpm_active) && error == 0) {
 177                 struct list_head * entry = dpm_active.prev;
 178                 struct device * dev = to_device(entry);
 179
 180                 get_device(dev);
 181                 up(&dpm_list_sem);
 182
 183                 error = suspend_device(dev, state);
 184
 185                 down(&dpm_list_sem);
 186
 187                 /* Check if the device got removed */
 188                 if (!list_empty(&dev->power.entry)) {
 189                         /* Move it to the dpm_off list */
 190                         if (!error)
 191                                 list_move(&dev->power.entry, &dpm_off);
 192                 }
 193                 if (error)
 194                         printk(KERN_ERR "Could not suspend device %s: "
 195                                 "error %d%s\n",
 196                                 kobject_name(&dev->kobj), error,
 197                                 error == -EAGAIN ? " (please convert to suspend_late)" : "");
 198                 put_device(dev);
 199         }
 200         up(&dpm_list_sem);
 201         if (error)
 202                 dpm_resume();
 203
 204         up(&dpm_sem);
 205         return error;
 206 }
 207
 208 EXPORT_SYMBOL_GPL(device_suspend);
 209
 210 /**
 211  *      device_power_down - Shut down special devices.
 212  *      @state:         Power state to enter.
 213  *
 214  *      Walk the dpm_off_irq list, calling ->power_down() for each device that
 215  *      couldn't power down the device with interrupts enabled. When we're
 216  *      done, power down system devices.
 217  */
 218
 219 int device_power_down(pm_message_t state)
 220 {
 221         int error = 0;
 222         struct device * dev;
 223
 224         while (!list_empty(&dpm_off)) {
 225                 struct list_head * entry = dpm_off.prev;
 226
 227                 dev = to_device(entry);
 228                 error = suspend_device_late(dev, state);
 229                 if (error)
 230                         goto Error;
 231                 list_move(&dev->power.entry, &dpm_off_irq);
 232         }
 233
 234         error = sysdev_suspend(state);
 235  Done:
 236         return error;
 237  Error:
 238         printk(KERN_ERR "Could not power down device %s: "
 239                 "error %d\n", kobject_name(&dev->kobj), error);
 240         dpm_power_up();
 241         goto Done;
 242 }
 243
 244 EXPORT_SYMBOL_GPL(device_power_down);
 245
 246 void __suspend_report_result(const char *function, void *fn, int ret)
 247 {
 248         if (ret) {
 249                 printk(KERN_ERR "%s(): ", function);
 250                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 251                 printk("%d\n", ret);
 252         }
 253 }
 254 EXPORT_SYMBOL_GPL(__suspend_report_result);