ACPI: Add a powered attribute to the AC driver

Signed-off-by: Brandon Philips <brandon@ifup.org>
---
 drivers/acpi/ac.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

Index: linux-2.6-rc/drivers/acpi/ac.c
===================================================================
--- linux-2.6-rc.orig/drivers/acpi/ac.c
+++ linux-2.6-rc/drivers/acpi/ac.c
@@ -211,6 +211,30 @@ static void acpi_ac_notify(acpi_handle h
 	return;
 }
 
+/*
+ * show_powered - read method for "powered" file in sysfs
+ */
+static ssize_t show_powered(struct acpi_device *dev, char *buf)
+{
+	struct acpi_ac *ac= (struct acpi_ac*)dev->driver_data;
+	return snprintf(buf, PAGE_SIZE, "%s\n", ac->state ? "on-line" : "off-line");
+}
+ACPI_DEVICE_ATTR(powered, S_IRUGO, show_powered, NULL);
+
+static void ac_remove_sysfs_files(struct acpi_device *ad) {
+	sysfs_remove_file(&ad->kobj, &acpi_device_attr_powered.attr);
+}
+
+static int ac_add_syfs_files(struct acpi_device *ad) {
+	int ret;
+
+	ret = sysfs_create_file(&ad->kobj, &acpi_device_attr_powered.attr);
+	if (ret)
+		ac_remove_sysfs_files(ad);;
+
+	return ret;
+}
+
 static int acpi_ac_add(struct acpi_device *device)
 {
 	int result = 0;
@@ -247,6 +271,11 @@ static int acpi_ac_add(struct acpi_devic
 		goto end;
 	}
 
+	device->driver_data = (void *)ac;
+
+	if (ac_add_syfs_files(device))
+		printk(KERN_ERR PREFIX "Unable to create sysfs files\n");
+
 	printk(KERN_INFO PREFIX "%s [%s] (%s)\n",
 	       acpi_device_name(device), acpi_device_bid(device),
 	       ac->state ? "on-line" : "off-line");
@@ -275,6 +304,7 @@ static int acpi_ac_remove(struct acpi_de
 					    ACPI_ALL_NOTIFY, acpi_ac_notify);
 
 	acpi_ac_remove_fs(device);
+	ac_remove_sysfs_files(device);
 
 	kfree(ac);