Index: linux-2.6/include/linux/pm.h
===================================================================
--- linux-2.6.orig/include/linux/pm.h
+++ linux-2.6/include/linux/pm.h
@@ -408,6 +408,9 @@ enum rpm_request {
 };
 
 struct dev_pm_info {
+	spinlock_t		lock;
+	struct list_head	master_links;
+	struct list_head	slave_links;
 	pm_message_t		power_state;
 	unsigned int		can_wakeup:1;
 	unsigned int		should_wakeup:1;
@@ -420,7 +423,6 @@ struct dev_pm_info {
 	unsigned long		timer_expires;
 	struct work_struct	work;
 	wait_queue_head_t	wait_queue;
-	spinlock_t		lock;
 	atomic_t		usage_count;
 	atomic_t		child_count;
 	unsigned int		disable_depth:3;
Index: linux-2.6/drivers/base/power/power.h
===================================================================
--- linux-2.6.orig/drivers/base/power/power.h
+++ linux-2.6/drivers/base/power/power.h
@@ -1,3 +1,7 @@
+extern void device_pm_init(struct device *dev);
+extern void device_pm_add(struct device *dev);
+extern void device_pm_remove(struct device *dev);
+
 #ifdef CONFIG_PM_RUNTIME
 
 extern void pm_runtime_init(struct device *dev);
@@ -23,7 +27,8 @@ static inline struct device *to_device(s
 	return container_of(entry, struct device, power.entry);
 }
 
-extern void device_pm_init(struct device *dev);
+extern void device_pm_list_add(struct device *dev);
+extern void device_pm_list_remove(struct device *dev);
 extern void device_pm_add(struct device *);
 extern void device_pm_remove(struct device *);
 extern void device_pm_move_before(struct device *, struct device *);
@@ -32,17 +37,8 @@ extern void device_pm_move_last(struct d
 
 #else /* !CONFIG_PM_SLEEP */
 
-static inline void device_pm_init(struct device *dev)
-{
-	pm_runtime_init(dev);
-}
-
-static inline void device_pm_remove(struct device *dev)
-{
-	pm_runtime_remove(dev);
-}
-
-static inline void device_pm_add(struct device *dev) {}
+static inline void device_pm_list_add(struct device *dev) {}
+static inline void device_pm_list_remove(struct device *dev) {}
 static inline void device_pm_move_before(struct device *deva,
 					 struct device *devb) {}
 static inline void device_pm_move_after(struct device *deva,
@@ -60,7 +56,11 @@ static inline void device_pm_move_last(s
 extern int dpm_sysfs_add(struct device *);
 extern void dpm_sysfs_remove(struct device *);
 
-#else /* CONFIG_PM */
+/* drivers/base/power/link.c */
+extern int pm_link_init(void);
+extern void pm_link_remove_all(struct device *dev);
+
+#else /* !CONFIG_PM */
 
 static inline int dpm_sysfs_add(struct device *dev)
 {
@@ -71,4 +71,7 @@ static inline void dpm_sysfs_remove(stru
 {
 }
 
-#endif
+static inline int pm_link_init(void) { return 0; }
+static inline void pm_link_remove_all(struct device *dev) {}
+
+#endif  /* !CONFIG_PM */
Index: linux-2.6/drivers/base/core.c
===================================================================
--- linux-2.6.orig/drivers/base/core.c
+++ linux-2.6/drivers/base/core.c
@@ -1252,9 +1252,13 @@ int __init devices_init(void)
 	sysfs_dev_char_kobj = kobject_create_and_add("char", dev_kobj);
 	if (!sysfs_dev_char_kobj)
 		goto char_kobj_err;
+	if (pm_link_init())
+		goto pm_link_err;
 
 	return 0;
 
+ pm_link_err:
+	kobject_put(sysfs_dev_char_kobj);
  char_kobj_err:
 	kobject_put(sysfs_dev_block_kobj);
  block_kobj_err:
Index: linux-2.6/include/linux/pm_link.h
===================================================================
--- /dev/null
+++ linux-2.6/include/linux/pm_link.h
@@ -0,0 +1,30 @@
+/*
+ * include/linux/pm_link.h - PM links manipulation core.
+ *
+ * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#ifndef _LINUX_PM_LINK_H
+#define _LINUX_PM_LINK_H
+
+#include <linux/list.h>
+
+struct device;
+
+struct pm_link {
+	struct device *master;
+	struct list_head master_hook;
+	struct device *slave;
+	struct list_head slave_hook;
+};
+
+extern int pm_link_add(struct device *slave, struct device *master);
+extern void pm_link_remove(struct device *dev, struct device *master);
+extern int device_for_each_master(struct device *slave, void *data,
+			   int (*fn)(struct device *dev, void *data));
+extern int device_for_each_slave(struct device *master, void *data,
+			  int (*fn)(struct device *dev, void *data));
+
+#endif
Index: linux-2.6/drivers/base/power/Makefile
===================================================================
--- linux-2.6.orig/drivers/base/power/Makefile
+++ linux-2.6/drivers/base/power/Makefile
@@ -1,4 +1,4 @@
-obj-$(CONFIG_PM)	+= sysfs.o
+obj-$(CONFIG_PM)	+= sysfs.o common.o
 obj-$(CONFIG_PM_SLEEP)	+= main.o
 obj-$(CONFIG_PM_RUNTIME)	+= runtime.o
 obj-$(CONFIG_PM_TRACE_RTC)	+= trace.o
Index: linux-2.6/drivers/base/power/runtime.c
===================================================================
--- linux-2.6.orig/drivers/base/power/runtime.c
+++ linux-2.6/drivers/base/power/runtime.c
@@ -972,8 +972,6 @@ EXPORT_SYMBOL_GPL(pm_runtime_enable);
  */
 void pm_runtime_init(struct device *dev)
 {
-	spin_lock_init(&dev->power.lock);
-
 	dev->power.runtime_status = RPM_SUSPENDED;
 	dev->power.idle_notification = false;
 
@@ -993,8 +991,6 @@ void pm_runtime_init(struct device *dev)
 	dev->power.timer_expires = 0;
 	setup_timer(&dev->power.suspend_timer, pm_suspend_timer_fn,
 			(unsigned long)dev);
-
-	init_waitqueue_head(&dev->power.wait_queue);
 }
 
 /**
Index: linux-2.6/drivers/base/power/main.c
===================================================================
--- linux-2.6.orig/drivers/base/power/main.c
+++ linux-2.6/drivers/base/power/main.c
@@ -21,6 +21,7 @@
 #include <linux/kallsyms.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
+#include <linux/pm_link.h>
 #include <linux/pm_runtime.h>
 #include <linux/resume-trace.h>
 #include <linux/rwsem.h>
@@ -50,16 +51,6 @@ static DEFINE_MUTEX(dpm_list_mtx);
 static bool transition_started;
 
 /**
- * device_pm_init - Initialize the PM-related part of a device object.
- * @dev: Device object being initialized.
- */
-void device_pm_init(struct device *dev)
-{
-	dev->power.status = DPM_ON;
-	pm_runtime_init(dev);
-}
-
-/**
  * device_pm_lock - Lock the list of active devices used by the PM core.
  */
 void device_pm_lock(void)
@@ -76,14 +67,11 @@ void device_pm_unlock(void)
 }
 
 /**
- * device_pm_add - Add a device to the PM core's list of active devices.
+ * device_pm_list_add - Add a device to the PM core's list of active devices.
  * @dev: Device to add to the list.
  */
-void device_pm_add(struct device *dev)
+void device_pm_list_add(struct device *dev)
 {
-	pr_debug("PM: Adding info for %s:%s\n",
-		 dev->bus ? dev->bus->name : "No Bus",
-		 kobject_name(&dev->kobj));
 	mutex_lock(&dpm_list_mtx);
 	if (dev->parent) {
 		if (dev->parent->power.status >= DPM_SUSPENDING)
@@ -97,24 +85,19 @@ void device_pm_add(struct device *dev)
 		 */
 		dev_WARN(dev, "Parentless device registered during a PM transaction\n");
 	}
-
 	list_add_tail(&dev->power.entry, &dpm_list);
 	mutex_unlock(&dpm_list_mtx);
 }
 
 /**
- * device_pm_remove - Remove a device from the PM core's list of active devices.
+ * device_pm_list_remove - Remove a device from the PM core's list of devices.
  * @dev: Device to be removed from the list.
  */
-void device_pm_remove(struct device *dev)
+void device_pm_list_remove(struct device *dev)
 {
-	pr_debug("PM: Removing info for %s:%s\n",
-		 dev->bus ? dev->bus->name : "No Bus",
-		 kobject_name(&dev->kobj));
 	mutex_lock(&dpm_list_mtx);
 	list_del_init(&dev->power.entry);
 	mutex_unlock(&dpm_list_mtx);
-	pm_runtime_remove(dev);
 }
 
 /**
Index: linux-2.6/drivers/base/power/common.c
===================================================================
--- /dev/null
+++ linux-2.6/drivers/base/power/common.c
@@ -0,0 +1,279 @@
+/*
+ * drivers/base/power/common.c - device PM common functions.
+ *
+ * Copyright (c) 2009 Rafael J. Wysocki <rjw@sisk.pl>, Novell Inc.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/rculist.h>
+#include <linux/device.h>
+#include <linux/srcu.h>
+#include <linux/pm_link.h>
+
+#include "power.h"
+
+/**
+ * device_pm_init - Initialize the PM part of a device object.
+ * @dev: Device object being initialized.
+ */
+void device_pm_init(struct device *dev)
+{
+	dev->power.status = DPM_ON;
+	spin_lock_init(&dev->power.lock);
+	INIT_LIST_HEAD(&dev->power.master_links);
+	INIT_LIST_HEAD(&dev->power.slave_links);
+	pm_runtime_init(dev);
+}
+
+/**
+ * device_pm_add - Handle the PM part of a device added to device tree.
+ * @dev: Device object being added to device tree.
+ */
+void device_pm_add(struct device *dev)
+{
+	pr_debug("PM: Adding info for %s:%s\n",
+		 dev->bus ? dev->bus->name : "No Bus",
+		 kobject_name(&dev->kobj));
+	device_pm_list_add(dev);
+}
+
+/**
+ * device_pm_remove - Handle the PM part of a device removed from device tree.
+ * @dev: Device object being removed from device tree.
+ */
+void device_pm_remove(struct device *dev)
+{
+	pr_debug("PM: Removing info for %s:%s\n",
+		 dev->bus ? dev->bus->name : "No Bus",
+		 kobject_name(&dev->kobj));
+	device_pm_list_remove(dev);
+	pm_runtime_remove(dev);
+	pm_link_remove_all(dev);
+}
+
+/*
+ * PM links framework.
+ *
+ * There are PM dependencies between devices that are not reflected by the
+ * structure of the device tree.  In other words, as far as PM is concerned, a
+ * device may depend on some other devices which are not its children and none
+ * of which is its parent.
+ *
+ * Every such dependency involves two devices, one of which is a "master" and
+ * the other of which is a "slave", meaning that the "slave" have to be
+ * suspended before the "master" and cannot be woken up before it.  Thus every
+ * device can be given two lists of "dependency objects", one for the
+ * dependencies where the device is the "master" and the other for the
+ * dependencies where the device is the "slave".  Then, each "dependency object"
+ * can be represented as 'struct pm_link' as defined in include/linux/pm_link.h.
+ *
+ * The PM links of a device can help decide when the device should be suspended
+ * or resumed.  Namely, In addition to checking the device's parent, the PM core
+ * can walk the list of its "masters" and check their PM status.  Similarly, in
+ * addition to walking the list of a device's children, the PM core can walk the
+ * list of its "slaves".
+ */
+
+static struct srcu_struct pm_link_ss;
+static DEFINE_MUTEX(pm_link_mtx);
+
+/**
+ * pm_link_add - Create a PM link object connecting two devices.
+ * @slave: Device to be the slave in this link.
+ * @master: Device to be the master in this link.
+ */
+int pm_link_add(struct device *slave, struct device *master)
+{
+	struct pm_link *link;
+	int error = -ENODEV;
+
+	if (!get_device(master))
+		return error;
+
+	if (!get_device(slave))
+		goto err_slave;
+
+	link = kzalloc(sizeof(*link), GFP_KERNEL);
+	if (!link)
+		goto err_link;
+
+	dev_dbg(slave, "PM: Creating PM link to (master) %s %s\n",
+		dev_driver_string(master), dev_name(master));
+
+	link->master = master;
+	INIT_LIST_HEAD(&link->master_hook);
+	link->slave = slave;
+	INIT_LIST_HEAD(&link->slave_hook);
+
+	spin_lock_irq(&master->power.lock);
+	list_add_tail_rcu(&link->master_hook, &master->power.master_links);
+	spin_unlock_irq(&master->power.lock);
+
+	spin_lock_irq(&slave->power.lock);
+	list_add_tail_rcu(&link->slave_hook, &slave->power.slave_links);
+	spin_unlock_irq(&slave->power.lock);
+
+	return 0;
+
+ err_link:
+	error = -ENOMEM;
+	put_device(slave);
+
+ err_slave:
+	put_device(master);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(pm_link_add);
+
+/**
+ * __pm_link_remove - Remove a PM link object.
+ * @link: PM link object to remove
+ */
+static void __pm_link_remove(struct pm_link *link)
+{
+	struct device *master = link->master;
+	struct device *slave = link->slave;
+
+	dev_dbg(slave, "PM: Removing PM link to (master) %s %s\n",
+		dev_driver_string(master), dev_name(master));
+
+	spin_lock_irq(&master->power.lock);
+	list_del_rcu(&link->master_hook);
+	spin_unlock_irq(&master->power.lock);
+
+	spin_lock_irq(&slave->power.lock);
+	list_del_rcu(&link->slave_hook);
+	spin_unlock_irq(&slave->power.lock);
+
+	synchronize_srcu(&pm_link_ss);
+
+	kfree(link);
+
+	put_device(master);
+	put_device(slave);
+}
+
+/**
+ * pm_link_remove_all - Remove all PM link objects for given device.
+ * @dev: Device to handle.
+ */
+void pm_link_remove_all(struct device *dev)
+{
+	struct pm_link *link, *n;
+
+	mutex_lock(&pm_link_mtx);
+
+	list_for_each_entry_safe(link, n, &dev->power.master_links, master_hook)
+		__pm_link_remove(link);
+
+	list_for_each_entry_safe(link, n, &dev->power.slave_links, slave_hook)
+		__pm_link_remove(link);
+
+	mutex_unlock(&pm_link_mtx);
+}
+
+/**
+ * pm_link_remove - Remove a PM link object connecting two devices.
+ * @dev: Slave device of the PM link to remove.
+ * @master: Master device of the PM link to remove.
+ */
+void pm_link_remove(struct device *dev, struct device *master)
+{
+	struct pm_link *link, *n;
+
+	mutex_lock(&pm_link_mtx);
+
+	list_for_each_entry_safe(link, n, &dev->power.slave_links, slave_hook) {
+		if (link->master != master)
+			continue;
+
+		__pm_link_remove(link);
+		break;
+	}
+
+	mutex_unlock(&pm_link_mtx);
+}
+EXPORT_SYMBOL_GPL(pm_link_remove);
+
+/**
+ * device_for_each_master - Execute given function for each master of a device.
+ * @slave: Device whose masters to execute the function for.
+ * @data: Data pointer to pass to the function.
+ * @fn: Function to execute for each master of @slave.
+ *
+ * The function is executed for the parent of the device, if there is one, and
+ * for each device connected to it via a pm_link object where @slave is the
+ * "slave".
+ */
+int device_for_each_master(struct device *slave, void *data,
+			   int (*fn)(struct device *dev, void *data))
+{
+	struct pm_link *link;
+	int idx;
+	int error = 0;
+
+	if (slave->parent) {
+		error = fn(slave->parent, data);
+		if (error)
+			return error;
+	}
+
+	idx = srcu_read_lock(&pm_link_ss);
+
+	list_for_each_entry(link, &slave->power.slave_links, slave_hook) {
+		struct device *master = link->master;
+
+		error = fn(master, data);
+		if (error)
+			break;
+	}
+
+	srcu_read_unlock(&pm_link_ss, idx);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_for_each_master);
+
+/**
+ * device_for_each_slave - Execute given function for each slave of a device.
+ * @master: Device whose slaves to execute the function for.
+ * @data: Data pointer to pass to the function.
+ * @fn: Function to execute for each slave of @master.
+ *
+ * The function is executed for all children of the device, if there are any,
+ * and for each device connected to it via a pm_link object where @master is the
+ * "master".
+ */
+int device_for_each_slave(struct device *master, void *data,
+			  int (*fn)(struct device *dev, void *data))
+{
+	struct pm_link *link;
+	int idx;
+	int error;
+
+	error = device_for_each_child(master, data, fn);
+	if (error)
+		return error;
+
+	idx = srcu_read_lock(&pm_link_ss);
+
+	list_for_each_entry(link, &master->power.master_links, master_hook) {
+		struct device *slave = link->slave;
+
+		error = fn(slave, data);
+		if (error)
+			break;
+	}
+
+	srcu_read_unlock(&pm_link_ss, idx);
+
+	return error;
+}
+EXPORT_SYMBOL_GPL(device_for_each_slave);
+
+int __init pm_link_init(void)
+{
+	return init_srcu_struct(&pm_link_ss);
+}
Index: linux-2.6/drivers/acpi/glue.c
===================================================================
--- linux-2.6.orig/drivers/acpi/glue.c
+++ linux-2.6/drivers/acpi/glue.c
@@ -11,6 +11,7 @@
 #include <linux/device.h>
 #include <linux/rwsem.h>
 #include <linux/acpi.h>
+#include <linux/pm_link.h>
 
 #define ACPI_GLUE_DEBUG	0
 #if ACPI_GLUE_DEBUG
@@ -170,6 +171,7 @@ static int acpi_bind_one(struct device *
 			device_set_wakeup_enable(dev,
 						acpi_dev->wakeup.state.enabled);
 		}
+		pm_link_add(dev, &acpi_dev->dev);
 	}
 
 	return 0;
@@ -189,6 +191,7 @@ static int acpi_unbind_one(struct device
 					&acpi_dev)) {
 			sysfs_remove_link(&dev->kobj, "firmware_node");
 			sysfs_remove_link(&acpi_dev->dev.kobj, "physical_node");
+			pm_link_remove(dev, &acpi_dev->dev);
 		}
 
 		acpi_detach_data(dev->archdata.acpi_handle,
