drivers/base/power/main.c

   1 /*
   2  * drivers/base/power/main.c - Where the driver meets power management.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Open Source Development Lab
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  *
  10  * The driver model core calls device_pm_add() when a device is registered.
  11  * This will intialize the embedded device_pm_info object in the device
  12  * and add it to the list of power-controlled devices. sysfs entries for
  13  * controlling device power management will also be added.
  14  *
  15  * A different set of lists than the global subsystem list are used to
  16  * keep track of power info because we use different lists to hold
  17  * devices based on what stage of the power management process they
  18  * are in. The power domain dependencies may also differ from the
  19  * ancestral dependencies that the subsystem list maintains.
  20  */
  21
  22 #include <linux/device.h>
  23 #include <linux/kallsyms.h>
  24 #include <linux/mutex.h>
  25 #include <linux/pm.h>
  26 #include <linux/resume-trace.h>
  27 #include <linux/rwsem.h>
  28
  29 #include "../base.h"
  30 #include "power.h"
  31
  32 /*
  33  * The entries in the dpm_active list are in a depth first order, simply
  34  * because children are guaranteed to be discovered after parents, and
  35  * are inserted at the back of the list on discovery.
  36  *
  37  * All the other lists are kept in the same order, for consistency.
  38  * However the lists aren't always traversed in the same order.
  39  * Semaphores must be acquired from the top (i.e., front) down
  40  * and released in the opposite order.  Devices must be suspended
  41  * from the bottom (i.e., end) up and resumed in the opposite order.
  42  * That way no parent will be suspended while it still has an active
  43  * child.
  44  *
  45  * Since device_pm_add() may be called with a device semaphore held,
  46  * we must never try to acquire a device semaphore while holding
  47  * dpm_list_mutex.
  48  */
  49
  50 LIST_HEAD(dpm_active);
  51 static LIST_HEAD(dpm_off);
  52 static LIST_HEAD(dpm_off_irq);
  53
  54 static DEFINE_MUTEX(dpm_list_mtx);
  55
  56 /* 'true' if all devices have been suspended, protected by dpm_list_mtx */
  57 static bool all_sleeping;
  58
  59 /**
  60  *      device_pm_add - add a device to the list of active devices
  61  *      @dev:   Device to be added to the list
  62  */
  63 int device_pm_add(struct device *dev)
  64 {
  65         int error;
  66
  67         pr_debug("PM: Adding info for %s:%s\n",
  68                  dev->bus ? dev->bus->name : "No Bus",
  69                  kobject_name(&dev->kobj));
  70         mutex_lock(&dpm_list_mtx);
  71         if ((dev->parent && dev->parent->power.sleeping) || all_sleeping) {
  72                 if (dev->parent->power.sleeping)
  73                         dev_warn(dev, "parent %s is sleeping\n",
  74                                 dev->parent->bus_id);
  75                 else
  76                         dev_warn(dev, "all devices are sleeping\n");
  77                 WARN_ON(true);
  78         }
  79         error = dpm_sysfs_add(dev);
  80         if (!error)
  81                 list_add_tail(&dev->power.entry, &dpm_active);
  82         mutex_unlock(&dpm_list_mtx);
  83         return error;
  84 }
  85
  86 /**
  87  *      device_pm_remove - remove a device from the list of active devices
  88  *      @dev:   Device to be removed from the list
  89  *
  90  *      This function also removes the device's PM-related sysfs attributes.
  91  */
  92 void device_pm_remove(struct device *dev)
  93 {
  94         pr_debug("PM: Removing info for %s:%s\n",
  95                  dev->bus ? dev->bus->name : "No Bus",
  96                  kobject_name(&dev->kobj));
  97         mutex_lock(&dpm_list_mtx);
  98         dpm_sysfs_remove(dev);
  99         list_del_init(&dev->power.entry);
 100         mutex_unlock(&dpm_list_mtx);
 101 }
 102
 103 /*------------------------- Resume routines -------------------------*/
 104
 105 /**
 106  *      resume_device_early - Power on one device (early resume).
 107  *      @dev:   Device.
 108  *
 109  *      Must be called with interrupts disabled.
 110  */
 111 static int resume_device_early(struct device *dev)
 112 {
 113         int error = 0;
 114
 115         TRACE_DEVICE(dev);
 116         TRACE_RESUME(0);
 117
 118         if (dev->bus && dev->bus->resume_early) {
 119                 dev_dbg(dev, "EARLY resume\n");
 120                 error = dev->bus->resume_early(dev);
 121         }
 122
 123         TRACE_RESUME(error);
 124         return error;
 125 }
 126
 127 /**
 128  *      dpm_power_up - Power on all regular (non-sysdev) devices.
 129  *
 130  *      Walk the dpm_off_irq list and power each device up. This
 131  *      is used for devices that required they be powered down with
 132  *      interrupts disabled. As devices are powered on, they are moved
 133  *      to the dpm_off list.
 134  *
 135  *      Must be called with interrupts disabled and only one CPU running.
 136  */
 137 static void dpm_power_up(void)
 138 {
 139
 140         while (!list_empty(&dpm_off_irq)) {
 141                 struct list_head *entry = dpm_off_irq.next;
 142                 struct device *dev = to_device(entry);
 143
 144                 list_move_tail(entry, &dpm_off);
 145                 resume_device_early(dev);
 146         }
 147 }
 148
 149 /**
 150  *      device_power_up - Turn on all devices that need special attention.
 151  *
 152  *      Power on system devices, then devices that required we shut them down
 153  *      with interrupts disabled.
 154  *
 155  *      Must be called with interrupts disabled.
 156  */
 157 void device_power_up(void)
 158 {
 159         sysdev_resume();
 160         dpm_power_up();
 161 }
 162 EXPORT_SYMBOL_GPL(device_power_up);
 163
 164 /**
 165  *      resume_device - Restore state for one device.
 166  *      @dev:   Device.
 167  *
 168  */
 169 static int resume_device(struct device *dev)
 170 {
 171         int error = 0;
 172
 173         TRACE_DEVICE(dev);
 174         TRACE_RESUME(0);
 175
 176         down(&dev->sem);
 177
 178         if (dev->bus && dev->bus->resume) {
 179                 dev_dbg(dev,"resuming\n");
 180                 error = dev->bus->resume(dev);
 181         }
 182
 183         if (!error && dev->type && dev->type->resume) {
 184                 dev_dbg(dev,"resuming\n");
 185                 error = dev->type->resume(dev);
 186         }
 187
 188         if (!error && dev->class && dev->class->resume) {
 189                 dev_dbg(dev,"class resume\n");
 190                 error = dev->class->resume(dev);
 191         }
 192
 193         up(&dev->sem);
 194
 195         TRACE_RESUME(error);
 196         return error;
 197 }
 198
 199 /**
 200  *      dpm_resume - Resume every device.
 201  *
 202  *      Resume the devices that have either not gone through
 203  *      the late suspend, or that did go through it but also
 204  *      went through the early resume.
 205  *
 206  *      Take devices from the dpm_off_list, resume them,
 207  *      and put them on the dpm_locked list.
 208  */
 209 static void dpm_resume(void)
 210 {
 211         mutex_lock(&dpm_list_mtx);
 212         all_sleeping = false;
 213         while(!list_empty(&dpm_off)) {
 214                 struct list_head *entry = dpm_off.next;
 215                 struct device *dev = to_device(entry);
 216
 217                 list_move_tail(entry, &dpm_active);
 218                 dev->power.sleeping = false;
 219                 mutex_unlock(&dpm_list_mtx);
 220                 resume_device(dev);
 221                 mutex_lock(&dpm_list_mtx);
 222         }
 223         mutex_unlock(&dpm_list_mtx);
 224 }
 225
 226 /**
 227  *      device_resume - Restore state of each device in system.
 228  *
 229  *      Resume all the devices, unlock them all, and allow new
 230  *      devices to be registered once again.
 231  */
 232 void device_resume(void)
 233 {
 234         might_sleep();
 235         dpm_resume();
 236 }
 237 EXPORT_SYMBOL_GPL(device_resume);
 238
 239
 240 /*------------------------- Suspend routines -------------------------*/
 241
 242 static inline char *suspend_verb(u32 event)
 243 {
 244         switch (event) {
 245         case PM_EVENT_SUSPEND:  return "suspend";
 246         case PM_EVENT_FREEZE:   return "freeze";
 247         case PM_EVENT_PRETHAW:  return "prethaw";
 248         default:                return "(unknown suspend event)";
 249         }
 250 }
 251
 252 static void
 253 suspend_device_dbg(struct device *dev, pm_message_t state, char *info)
 254 {
 255         dev_dbg(dev, "%s%s%s\n", info, suspend_verb(state.event),
 256                 ((state.event == PM_EVENT_SUSPEND) && device_may_wakeup(dev)) ?
 257                 ", may wakeup" : "");
 258 }
 259
 260 /**
 261  *      suspend_device_late - Shut down one device (late suspend).
 262  *      @dev:   Device.
 263  *      @state: Power state device is entering.
 264  *
 265  *      This is called with interrupts off and only a single CPU running.
 266  */
 267 static int suspend_device_late(struct device *dev, pm_message_t state)
 268 {
 269         int error = 0;
 270
 271         if (dev->bus && dev->bus->suspend_late) {
 272                 suspend_device_dbg(dev, state, "LATE ");
 273                 error = dev->bus->suspend_late(dev, state);
 274                 suspend_report_result(dev->bus->suspend_late, error);
 275         }
 276         return error;
 277 }
 278
 279 /**
 280  *      device_power_down - Shut down special devices.
 281  *      @state:         Power state to enter.
 282  *
 283  *      Power down devices that require interrupts to be disabled
 284  *      and move them from the dpm_off list to the dpm_off_irq list.
 285  *      Then power down system devices.
 286  *
 287  *      Must be called with interrupts disabled and only one CPU running.
 288  */
 289 int device_power_down(pm_message_t state)
 290 {
 291         int error = 0;
 292
 293         while (!list_empty(&dpm_off)) {
 294                 struct list_head *entry = dpm_off.prev;
 295                 struct device *dev = to_device(entry);
 296
 297                 error = suspend_device_late(dev, state);
 298                 if (error) {
 299                         printk(KERN_ERR "Could not power down device %s: "
 300                                         "error %d\n",
 301                                         kobject_name(&dev->kobj), error);
 302                         break;
 303                 }
 304                 if (!list_empty(&dev->power.entry))
 305                         list_move(&dev->power.entry, &dpm_off_irq);
 306         }
 307
 308         if (!error)
 309                 error = sysdev_suspend(state);
 310         if (error)
 311                 dpm_power_up();
 312         return error;
 313 }
 314 EXPORT_SYMBOL_GPL(device_power_down);
 315
 316 /**
 317  *      suspend_device - Save state of one device.
 318  *      @dev:   Device.
 319  *      @state: Power state device is entering.
 320  */
 321 static int suspend_device(struct device *dev, pm_message_t state)
 322 {
 323         int error = 0;
 324
 325         down(&dev->sem);
 326
 327         if (dev->class && dev->class->suspend) {
 328                 suspend_device_dbg(dev, state, "class ");
 329                 error = dev->class->suspend(dev, state);
 330                 suspend_report_result(dev->class->suspend, error);
 331         }
 332
 333         if (!error && dev->type && dev->type->suspend) {
 334                 suspend_device_dbg(dev, state, "type ");
 335                 error = dev->type->suspend(dev, state);
 336                 suspend_report_result(dev->type->suspend, error);
 337         }
 338
 339         if (!error && dev->bus && dev->bus->suspend) {
 340                 suspend_device_dbg(dev, state, "");
 341                 error = dev->bus->suspend(dev, state);
 342                 suspend_report_result(dev->bus->suspend, error);
 343         }
 344
 345         up(&dev->sem);
 346
 347         return error;
 348 }
 349
 350 /**
 351  *      dpm_suspend - Suspend every device.
 352  *      @state: Power state to put each device in.
 353  *
 354  *      Walk the dpm_locked list.  Suspend each device and move it
 355  *      to the dpm_off list.
 356  *
 357  *      (For historical reasons, if it returns -EAGAIN, that used to mean
 358  *      that the device would be called again with interrupts disabled.
 359  *      These days, we use the "suspend_late()" callback for that, so we
 360  *      print a warning and consider it an error).
 361  */
 362 static int dpm_suspend(pm_message_t state)
 363 {
 364         int error = 0;
 365
 366         mutex_lock(&dpm_list_mtx);
 367         while (!list_empty(&dpm_active)) {
 368                 struct list_head *entry = dpm_active.prev;
 369                 struct device *dev = to_device(entry);
 370
 371                 WARN_ON(dev->parent && dev->parent->power.sleeping);
 372
 373                 dev->power.sleeping = true;
 374                 mutex_unlock(&dpm_list_mtx);
 375                 error = suspend_device(dev, state);
 376                 mutex_lock(&dpm_list_mtx);
 377                 if (error) {
 378                         printk(KERN_ERR "Could not suspend device %s: "
 379                                         "error %d%s\n",
 380                                         kobject_name(&dev->kobj),
 381                                         error,
 382                                         (error == -EAGAIN ?
 383                                         " (please convert to suspend_late)" :
 384                                         ""));
 385                         dev->power.sleeping = false;
 386                         break;
 387                 }
 388                 if (!list_empty(&dev->power.entry))
 389                         list_move(&dev->power.entry, &dpm_off);
 390         }
 391         if (!error)
 392                 all_sleeping = true;
 393         mutex_unlock(&dpm_list_mtx);
 394
 395         return error;
 396 }
 397
 398 /**
 399  *      device_suspend - Save state and stop all devices in system.
 400  *      @state: new power management state
 401  *
 402  *      Prevent new devices from being registered, then lock all devices
 403  *      and suspend them.
 404  */
 405 int device_suspend(pm_message_t state)
 406 {
 407         int error;
 408
 409         might_sleep();
 410         error = dpm_suspend(state);
 411         if (error)
 412                 device_resume();
 413         return error;
 414 }
 415 EXPORT_SYMBOL_GPL(device_suspend);
 416
 417 void __suspend_report_result(const char *function, void *fn, int ret)
 418 {
 419         if (ret) {
 420                 printk(KERN_ERR "%s(): ", function);
 421                 print_fn_descriptor_symbol("%s() returns ", (unsigned long)fn);
 422                 printk("%d\n", ret);
 423         }
 424 }
 425 EXPORT_SYMBOL_GPL(__suspend_report_result);