[power] Begin to add sysfs files for controlling device power states.

- Moves sysfs controls to drivers/base/power/sysfs.c
- Creates dpm_sysfs_{add,remove} to add/remove sysfs attribute group.
- Creates 'state' file in 'pm' directory that properly controls device
  power state at runtime.

drivers/base/power/Makefile

 obj-y			:= shutdown.o
-obj-$(CONFIG_PM)	+= main.o suspend.o resume.o runtime.o 
+obj-$(CONFIG_PM)	+= main.o suspend.o resume.o runtime.o sysfs.o

drivers/base/power/main.c

@@ -31,15 +31,6 @@ LIST_HEAD(dpm_off_irq);
 
 DECLARE_MUTEX(dpm_sem);
 
-static struct attribute power_attrs[] = {
-	{ .name = NULL },
-};
-static struct attribute_group pm_attr_group = {
-	.name	= "pm",
-	.attrs	= power_attrs,
-};
-
-
 /*
  * PM Reference Counting.
  */
@@ -88,7 +79,8 @@ int device_pm_add(struct device * dev)
 	down(&dpm_sem);
 	list_add_tail(&dev->power.entry,&dpm_active);
 	device_pm_set_parent(dev,dev->parent);
-	error = sysfs_create_group(&dev->kobj,&pm_attr_group);
+	if ((error = dpm_sysfs_add(dev)))
+		list_del(&dev->power.entry);
 	up(&dpm_sem);
 	return error;
 }
@@ -98,7 +90,7 @@ void device_pm_remove(struct device * dev)
 	pr_debug("PM: Removing info for %s:%s\n",
 		 dev->bus ? dev->bus->name : "No Bus", dev->kobj.name);
 	down(&dpm_sem);
-	sysfs_remove_group(&dev->kobj,&pm_attr_group);
+	dpm_sysfs_remove(dev);
 	list_del(&dev->power.entry);
 	up(&dpm_sem);
 }

drivers/base/power/sysfs.c

+/*
+ * drivers/base/power/sysfs.c - sysfs entries for device PM
+ */
+
+#include <linux/device.h>
+#include "power.h"
+
+static ssize_t state_show(struct device * dev, char * buf)
+{
+	return sprintf(buf,"%u\n",dev->power.power_state);
+}
+
+static ssize_t state_store(struct device * dev, const char * buf, size_t n)
+{
+	u32 state;
+	char * rest;
+	int error = 0;
+
+	state = simple_strtoul(buf,&rest,10);
+	if (rest)
+		return -EINVAL;
+	if (state)
+		error = dpm_runtime_suspend(dev,state);
+	else
+		dpm_runtime_resume(dev);
+	return error ? error : n;
+}
+
+DEVICE_ATTR(state,0644,state_show,state_store);
+
+
+
+static struct attribute * power_attrs[] = {
+	&dev_attr_state.attr,
+	NULL,
+};
+static struct attribute_group pm_attr_group = {
+	.name	= "pm",
+	.attrs	= power_attrs,
+};
+
+int dpm_sysfs_add(struct device * dev)
+{
+	return sysfs_create_group(&dev->kobj,&pm_attr_group);
+}
+
+void dpm_sysfs_remove(struct device * dev)
+{
+	sysfs_remove_group(&dev->kobj,&pm_attr_group);
+}