[ACPI] support button driver unload (Luming Yu)

http://bugzilla.kernel.org/show_bug.cgi?id=2281

drivers/acpi/button.c

@@ -108,6 +108,9 @@ static struct file_operations acpi_button_state_fops = {
    -------------------------------------------------------------------------- */
 
 static struct proc_dir_entry	*acpi_button_dir;
+struct acpi_device 	*fixed_pwr_button;
+struct acpi_device	*fixed_sleep_button;
+
 
 static int acpi_button_info_seq_show(struct seq_file *seq, void *offset)
 {
@@ -527,6 +530,12 @@ acpi_button_exit (void)
 {
 	ACPI_FUNCTION_TRACE("acpi_button_exit");
 
+	if(fixed_pwr_button) 
+		acpi_button_remove(fixed_pwr_button, ACPI_BUS_TYPE_POWER_BUTTON);
+
+	if(fixed_sleep_button)
+		acpi_button_remove(fixed_sleep_button, ACPI_BUS_TYPE_SLEEP_BUTTON);
+
 	acpi_bus_unregister_driver(&acpi_button_driver);
 
 	remove_proc_entry(ACPI_BUTTON_CLASS, acpi_root_dir);

drivers/acpi/scan.c

@@ -15,6 +15,8 @@ ACPI_MODULE_NAME		("scan")
 #define STRUCT_TO_INT(s)	(*((int*)&s))
 
 extern struct acpi_device		*acpi_root;
+extern struct acpi_device 		*fixed_pwr_button;
+extern struct acpi_device 		*fixed_sleep_button;
 
 
 #define ACPI_BUS_CLASS			"system_bus"
@@ -904,6 +906,10 @@ acpi_bus_scan_fixed (
 
 	ACPI_FUNCTION_TRACE("acpi_bus_scan_fixed");
 
+	fixed_pwr_button = NULL;
+	fixed_sleep_button = NULL;
+
+
 	if (!root)
 		return_VALUE(-ENODEV);
 
@@ -911,11 +917,11 @@ acpi_bus_scan_fixed (
 	 * Enumerate all fixed-feature devices.
 	 */
 	if (acpi_fadt.pwr_button == 0)
-		result = acpi_bus_add(&device, acpi_root, 
+		result = acpi_bus_add(&fixed_pwr_button, acpi_root, 
 			NULL, ACPI_BUS_TYPE_POWER_BUTTON);
 
 	if (acpi_fadt.sleep_button == 0)
-		result = acpi_bus_add(&device, acpi_root, 
+		result = acpi_bus_add(&fixed_sleep_button, acpi_root, 
 			NULL, ACPI_BUS_TYPE_SLEEP_BUTTON);
 
 	return_VALUE(result);