platform/chrome: cros_kbd_led_backlight: separate ACPI backend

cros_kbd_led_backlight uses ACPI_KEYBOARD_BACKLIGHT_WRITE and
ACPI_KEYBOARD_BACKLIGHT_READ for setting and getting the brightness
respectively.

Separate ACPI operations as an independent option for preparing the
driver to support other backends.

Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>

drivers/platform/chrome/Kconfig

@@ -128,14 +128,20 @@ config CROS_EC_PROTO
 
 config CROS_KBD_LED_BACKLIGHT
 	tristate "Backlight LED support for Chrome OS keyboards"
-	depends on LEDS_CLASS && ACPI
+	depends on LEDS_CLASS
 	help
 	  This option enables support for the keyboard backlight LEDs on
 	  select Chrome OS systems.
 
 	  To compile this driver as a module, choose M here: the
 	  module will be called cros_kbd_led_backlight.
 
+config CROS_KBD_LED_BACKLIGHT_ACPI
+	bool "ChromeOS keyboard backlight ACPI backend"
+	depends on ACPI && CROS_KBD_LED_BACKLIGHT
+	help
+	  ChromeOS keyboard backlight ACPI backend.
+
 config CROS_EC_CHARDEV
 	tristate "ChromeOS EC miscdevice"
 	depends on MFD_CROS_EC_DEV

drivers/platform/chrome/cros_kbd_led_backlight.c

@@ -13,15 +13,42 @@
 #include <linux/platform_device.h>
 #include <linux/slab.h>
 
+/**
+ * struct keyboard_led_drvdata - keyboard LED driver data.
+ * @init:			Init function.
+ * @brightness_get:		Get LED brightness level.
+ * @brightness_set:		Set LED brightness level.  Must not sleep.
+ * @brightness_set_blocking:	Set LED brightness level.  It can block the
+ *				caller for the time required for accessing a
+ *				LED device register
+ * @max_brightness:		Maximum brightness.
+ *
+ * See struct led_classdev in include/linux/leds.h for more details.
+ */
+struct keyboard_led_drvdata {
+	int (*init)(struct platform_device *pdev);
+
+	enum led_brightness (*brightness_get)(struct led_classdev *led_cdev);
+
+	void (*brightness_set)(struct led_classdev *led_cdev,
+			       enum led_brightness brightness);
+	int (*brightness_set_blocking)(struct led_classdev *led_cdev,
+				       enum led_brightness brightness);
+
+	enum led_brightness max_brightness;
+};
+
+#if IS_ENABLED(CONFIG_CROS_KBD_LED_BACKLIGHT_ACPI)
+
 /* Keyboard LED ACPI Device must be defined in firmware */
 #define ACPI_KEYBOARD_BACKLIGHT_DEVICE	"\\_SB.KBLT"
 #define ACPI_KEYBOARD_BACKLIGHT_READ	ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
 #define ACPI_KEYBOARD_BACKLIGHT_WRITE	ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
 
 #define ACPI_KEYBOARD_BACKLIGHT_MAX		100
 
-static void keyboard_led_set_brightness(struct led_classdev *cdev,
-					enum led_brightness brightness)
+static void keyboard_led_set_brightness_acpi(struct led_classdev *cdev,
+					     enum led_brightness brightness)
 {
 	union acpi_object param;
 	struct acpi_object_list input;
@@ -40,7 +67,7 @@ static void keyboard_led_set_brightness(struct led_classdev *cdev,
 }
 
 static enum led_brightness
-keyboard_led_get_brightness(struct led_classdev *cdev)
+keyboard_led_get_brightness_acpi(struct led_classdev *cdev)
 {
 	unsigned long long brightness;
 	acpi_status status;
@@ -56,12 +83,10 @@ keyboard_led_get_brightness(struct led_classdev *cdev)
 	return brightness;
 }
 
-static int keyboard_led_probe(struct platform_device *pdev)
+static int keyboard_led_init_acpi(struct platform_device *pdev)
 {
-	struct led_classdev *cdev;
 	acpi_handle handle;
 	acpi_status status;
-	int error;
 
 	/* Look for the keyboard LED ACPI Device */
 	status = acpi_get_handle(ACPI_ROOT_OBJECT,
@@ -73,15 +98,55 @@ static int keyboard_led_probe(struct platform_device *pdev)
 		return -ENXIO;
 	}
 
+	return 0;
+}
+
+static const struct keyboard_led_drvdata keyboard_led_drvdata_acpi = {
+	.init = keyboard_led_init_acpi,
+	.brightness_set = keyboard_led_set_brightness_acpi,
+	.brightness_get = keyboard_led_get_brightness_acpi,
+	.max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX,
+};
+
+#else /* IS_ENABLED(CONFIG_CROS_KBD_LED_BACKLIGHT_ACPI) */
+
+static int keyboard_led_init_acpi_null(struct platform_device *pdev)
+{
+	return -EOPNOTSUPP;
+}
+
+static const struct keyboard_led_drvdata keyboard_led_drvdata_acpi = {
+	.init = keyboard_led_init_acpi_null,
+};
+
+#endif /* IS_ENABLED(CONFIG_CROS_KBD_LED_BACKLIGHT_ACPI) */
+
+static int keyboard_led_probe(struct platform_device *pdev)
+{
+	struct led_classdev *cdev;
+	const struct keyboard_led_drvdata *drvdata;
+	int error;
+
+	drvdata = acpi_device_get_match_data(&pdev->dev);
+	if (!drvdata)
+		return -EINVAL;
+
+	if (drvdata->init) {
+		error = drvdata->init(pdev);
+		if (error)
+			return error;
+	}
+
 	cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
 	if (!cdev)
 		return -ENOMEM;
 
 	cdev->name = "chromeos::kbd_backlight";
-	cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
 	cdev->flags |= LED_CORE_SUSPENDRESUME;
-	cdev->brightness_set = keyboard_led_set_brightness;
-	cdev->brightness_get = keyboard_led_get_brightness;
+	cdev->max_brightness = drvdata->max_brightness;
+	cdev->brightness_set = drvdata->brightness_set;
+	cdev->brightness_set_blocking = drvdata->brightness_set_blocking;
+	cdev->brightness_get = drvdata->brightness_get;
 
 	error = devm_led_classdev_register(&pdev->dev, cdev);
 	if (error)
@@ -90,16 +155,16 @@ static int keyboard_led_probe(struct platform_device *pdev)
 	return 0;
 }
 
-static const struct acpi_device_id keyboard_led_id[] = {
-	{ "GOOG0002", 0 },
+static const struct acpi_device_id keyboard_led_acpi_match[] = {
+	{ "GOOG0002", (kernel_ulong_t)&keyboard_led_drvdata_acpi },
 	{ }
 };
-MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
+MODULE_DEVICE_TABLE(acpi, keyboard_led_acpi_match);
 
 static struct platform_driver keyboard_led_driver = {
 	.driver		= {
 		.name	= "chromeos-keyboard-leds",
-		.acpi_match_table = ACPI_PTR(keyboard_led_id),
+		.acpi_match_table = ACPI_PTR(keyboard_led_acpi_match),
 	},
 	.probe		= keyboard_led_probe,
 };