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 "power.h"
  24
  25 LIST_HEAD(dpm_active);
  26 LIST_HEAD(dpm_off);
  27 LIST_HEAD(dpm_off_irq);
  28
  29 DECLARE_MUTEX(dpm_sem);
  30 DECLARE_MUTEX(dpm_list_sem);
  31
  32 /**
  33  *      device_pm_set_parent - Specify power dependency.
  34  *      @dev:           Device who needs power.
  35  *      @parent:        Device that supplies power.
  36  *
  37  *      This function is used to manually describe a power-dependency
  38  *      relationship. It may be used to specify a transversal relationship
  39  *      (where the power supplier is not the physical (or electrical)
  40  *      ancestor of a specific device.
  41  *      The effect of this is that the supplier will not be powered down
  42  *      before the power dependent.
  43  */
  44
  45 void device_pm_set_parent(struct device * dev, struct device * parent)
  46 {
  47         put_device(dev->power.pm_parent);
  48         dev->power.pm_parent = get_device(parent);
  49 }
  50 EXPORT_SYMBOL_GPL(device_pm_set_parent);
  51
  52 int device_pm_add(struct device * dev)
  53 {
  54         int error;
  55
  56         pr_debug("PM: Adding info for %s:%s\n",
  57                  dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
  58         down(&dpm_list_sem);
  59         list_add_tail(&dev->power.entry, &dpm_active);
  60         device_pm_set_parent(dev, dev->parent);
  61         if ((error = dpm_sysfs_add(dev)))
  62                 list_del(&dev->power.entry);
  63         up(&dpm_list_sem);
  64         return error;
  65 }
  66
  67 void device_pm_remove(struct device * dev)
  68 {
  69         pr_debug("PM: Removing info for %s:%s\n",
  70                  dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
  71         down(&dpm_list_sem);
  72         dpm_sysfs_remove(dev);
  73         put_device(dev->power.pm_parent);
  74         list_del_init(&dev->power.entry);
  75         up(&dpm_list_sem);
  76 }
  77
  78