ACPI: asus_acpi: Add support for the generic backlight device

Add support for the generic backlight interface below /sys/class/backlight.
Keep the procfs brightness handling for backward compatibility.

[[email protected]: backlight users need to select BACKLIGHT_CLASS_DEVICE]

Signed-off-by: Holger Macht <[email protected]>
Signed-off-by: Andy Whitcroft <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Len Brown <[email protected]>

drivers/acpi/Kconfig

@@ -172,6 +172,7 @@ config ACPI_NUMA
 config ACPI_ASUS
         tristate "ASUS/Medion Laptop Extras"
 	depends on X86
+	select BACKLIGHT_CLASS_DEVICE
         ---help---
           This driver provides support for extra features of ACPI-compatible
           ASUS laptops. As some of Medion laptops are made by ASUS, it may also

drivers/acpi/asus_acpi.c

@@ -35,6 +35,7 @@
 #include <linux/init.h>
 #include <linux/types.h>
 #include <linux/proc_fs.h>
+#include <linux/backlight.h>
 #include <acpi/acpi_drivers.h>
 #include <acpi/acpi_bus.h>
 #include <asm/uaccess.h>
@@ -402,6 +403,8 @@ static struct model_data model_conf[END_MODEL] = {
 /* procdir we use */
 static struct proc_dir_entry *asus_proc_dir;
 
+static struct backlight_device *asus_backlight_device;
+
 /*
  * This header is made available to allow proper configuration given model,
  * revision number , ... this info cannot go in struct asus_hotk because it is
@@ -779,7 +782,7 @@ proc_write_lcd(struct file *file, const char __user * buffer,
 	return rv;
 }
 
-static int read_brightness(void)
+static int read_brightness(struct backlight_device *bd)
 {
 	int value;
 
@@ -801,21 +804,23 @@ static int read_brightness(void)
 /*
  * Change the brightness level
  */
-static void set_brightness(int value)
+static int set_brightness(int value)
 {
 	acpi_status status = 0;
+	int ret = 0;
 
 	/* SPLV laptop */
 	if (hotk->methods->brightness_set) {
 		if (!write_acpi_int(hotk->handle, hotk->methods->brightness_set,
 				    value, NULL))
 			printk(KERN_WARNING
 			       "Asus ACPI: Error changing brightness\n");
-		return;
+			ret = -EIO;
+		goto out;
 	}
 
 	/* No SPLV method if we are here, act as appropriate */
-	value -= read_brightness();
+	value -= read_brightness(NULL);
 	while (value != 0) {
 		status = acpi_evaluate_object(NULL, (value > 0) ?
 					      hotk->methods->brightness_up :
@@ -825,15 +830,22 @@ static void set_brightness(int value)
 		if (ACPI_FAILURE(status))
 			printk(KERN_WARNING
 			       "Asus ACPI: Error changing brightness\n");
+			ret = -EIO;
 	}
-	return;
+out:
+	return ret;
+}
+
+static int set_brightness_status(struct backlight_device *bd)
+{
+	return set_brightness(bd->props->brightness);
 }
 
 static int
 proc_read_brn(char *page, char **start, off_t off, int count, int *eof,
 	      void *data)
 {
-	return sprintf(page, "%d\n", read_brightness());
+	return sprintf(page, "%d\n", read_brightness(NULL));
 }
 
 static int
@@ -1333,6 +1345,26 @@ static int asus_hotk_remove(struct acpi_device *device, int type)
 	return 0;
 }
 
+static struct backlight_properties asus_backlight_data = {
+        .owner          = THIS_MODULE,
+        .get_brightness = read_brightness,
+        .update_status  = set_brightness_status,
+        .max_brightness = 15,
+};
+
+static void __exit asus_acpi_exit(void)
+{
+	if (asus_backlight_device)
+		backlight_device_unregister(asus_backlight_device);
+
+	acpi_bus_unregister_driver(&asus_hotk_driver);
+	remove_proc_entry(PROC_ASUS, acpi_root_dir);
+
+	kfree(asus_info);
+
+	return;
+}
+
 static int __init asus_acpi_init(void)
 {
 	int result;
@@ -1370,17 +1402,15 @@ static int __init asus_acpi_init(void)
 		return result;
 	}
 
-	return 0;
-}
-
-static void __exit asus_acpi_exit(void)
-{
-	acpi_bus_unregister_driver(&asus_hotk_driver);
-	remove_proc_entry(PROC_ASUS, acpi_root_dir);
-
-	kfree(asus_info);
+	asus_backlight_device = backlight_device_register("asus", NULL,
+							  &asus_backlight_data);
+        if (IS_ERR(asus_backlight_device)) {
+		printk(KERN_ERR "Could not register asus backlight device\n");
+		asus_backlight_device = NULL;
+		asus_acpi_exit();
+	}
 
-	return;
+	return 0;
 }
 
 module_init(asus_acpi_init);