[RFC PATCH 5/5] leds: lm3692x: Offload DT node locating and parsing to core

[Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>]

This comment serves as an example how led controller drivers
could be simplified if led-class/led-core would handle DT node
locating and parsing. leds-lm3692x was randomly selected from
drivers using 'devm_led_classdev_register_ext' API. No further
study was done :)

This commit HAS NOT BEEN TESTED at all. Only compile tested.
This is only RFC - Eg, request for comments. If people see some
of the ideas as useful then properly tested patch should be
provided.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
---
 drivers/leds/leds-lm3692x.c | 75 ++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 34 deletions(-)

diff --git a/drivers/leds/leds-lm3692x.c b/drivers/leds/leds-lm3692x.c
index 3d381f2f73d0..abe2b1113049 100644
--- a/drivers/leds/leds-lm3692x.c
+++ b/drivers/leds/leds-lm3692x.c
@@ -108,7 +108,7 @@
 struct lm3692x_led {
 	struct mutex lock;
 	struct i2c_client *client;
-	struct led_classdev led_dev;
+	struct led_init_data init_data;
 	struct regmap *regmap;
 	struct gpio_desc *enable_gpio;
 	struct regulator *regulator;
@@ -166,7 +166,8 @@ static int lm3692x_brightness_set(struct led_classdev *led_cdev,
 				enum led_brightness brt_val)
 {
 	struct lm3692x_led *led =
-			container_of(led_cdev, struct lm3692x_led, led_dev);
+			container_of(led_cdev->init_data, struct lm3692x_led,
+				     init_data);
 	int ret;
 	int led_brightness_lsb = (brt_val >> 5);
 
@@ -319,49 +320,56 @@ static int lm3692x_init(struct lm3692x_led *led)
 
 	return ret;
 }
-static int lm3692x_probe_dt(struct lm3692x_led *led)
+
+static int lm3692x_of_parse_cb(struct led_classdev *ld, struct fwnode_handle *fw,
+			       struct led_properties *props)
 {
-	struct fwnode_handle *child = NULL;
-	struct led_init_data init_data = {};
 	int ret;
+	struct lm3692x_led *led = container_of(ld->init_data,
+					       struct lm3692x_led, init_data);
+
+	ret = fwnode_property_read_u32(fw, "reg", &led->led_enable);
+	if (ret)
+		dev_err(&led->client->dev, "reg DT property missing\n");
+
+	return ret;
+}
+
+static const struct led_ops lm3692x_ops = {
+	.brightness_set_blocking = lm3692x_brightness_set,
+};
+
+static int lm3692x_probe_dt(struct lm3692x_led *led)
+{
+	void *ret;
 
 	led->enable_gpio = devm_gpiod_get_optional(&led->client->dev,
 						   "enable", GPIOD_OUT_LOW);
 	if (IS_ERR(led->enable_gpio)) {
-		ret = PTR_ERR(led->enable_gpio);
-		dev_err(&led->client->dev, "Failed to get enable gpio: %d\n",
-			ret);
-		return ret;
+		dev_err(&led->client->dev, "Failed to get enable gpio: %ld\n",
+			PTR_ERR(led->enable_gpio));
+		return PTR_ERR(led->enable_gpio);
 	}
 
 	led->regulator = devm_regulator_get(&led->client->dev, "vled");
 	if (IS_ERR(led->regulator))
 		led->regulator = NULL;
 
-	child = device_get_next_child_node(&led->client->dev, child);
-	if (!child) {
-		dev_err(&led->client->dev, "No LED Child node\n");
-		return -ENODEV;
-	}
-
-	fwnode_property_read_string(child, "linux,default-trigger",
-				    &led->led_dev.default_trigger);
-
-	ret = fwnode_property_read_u32(child, "reg", &led->led_enable);
-	if (ret) {
-		dev_err(&led->client->dev, "reg DT property missing\n");
-		return ret;
-	}
-
-	init_data.fwnode = child;
-	init_data.devicename = led->client->name;
-	init_data.default_label = ":";
-
-	ret = devm_led_classdev_register_ext(&led->client->dev, &led->led_dev,
-					     &init_data);
-	if (ret) {
-		dev_err(&led->client->dev, "led register err: %d\n", ret);
-		return ret;
+	/*
+	 * RFC_NOTE: Do we have fixed node name here or do we need another way to
+	 * do 'match'?
+	 */
+	led->init_data.of_match = of_match_ptr("led_node_name_here");
+	led->init_data.of_parse_cb = lm3692x_of_parse_cb;
+	led->init_data.devicename = led->client->name;
+	led->init_data.default_label = ":";
+
+	ret = devm_led_classdev_register_dt(&led->client->dev, &lm3692x_ops,
+					    &led->init_data);
+	if (IS_ERR(ret)) {
+		dev_err(&led->client->dev, "led register err: %ld\n",
+			PTR_ERR(ret));
+		return PTR_ERR(ret);
 	}
 
 	return 0;
@@ -379,7 +387,6 @@ static int lm3692x_probe(struct i2c_client *client,
 
 	mutex_init(&led->lock);
 	led->client = client;
-	led->led_dev.brightness_set_blocking = lm3692x_brightness_set;
 	led->model_id = id->driver_data;
 	i2c_set_clientdata(client, led);
 
-- 
2.21.0


-- 
Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
Simon says - in Latin please.
~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~
Thanks to Simon Glass for the translation =]