leds:lp55xx: use the private data instead of updating I2C device platform data

Currently, lp55xx_of_populate_pdata() allocates lp55xx_platform_data if
it's null. And it parses the DT and copies values into the
'client->dev.platform_data'. This may have architectural issue.
Platform data is configurable through the DT or I2C board info inside the
platform area. However, lp55xx common driver changes this configuration
when it is loaded. So 'client->dev.platform_data' is not null anymore.
Eventually, the driver initialization is not identical when it's unloaded
and loaded again.
The lp55xx common driver should use the private data, 'lp55xx_chip->pdata'
instead of changing the original platform data.

So, lp55xx_of_populate_pdata() is modified as follows.
* Do not update 'dev->platform_data'. Return the pointer of new allocated
lp55xx_platform_data. Then the driver points it to private data,
'lp55xx_chip->pdata'.
* Each lp55xx driver checks the pointer and handles an error case.

Then, original platform data configuration will be kept regardless of
loading or unloading the driver.
The driver allocates the memory and copies them from the DT if it's NULL.
After the driver is loaded again, 'client->dev.platform_data' is same as
initial load, so the driver is initialized identically.

Cc: Toshi Kikuchi <[e-mail]>
Cc: [e-mail]
Signed-off-by: Milo Kim <[e-mail]>
Signed-off-by: Jacek Anaszewski <[e-mail]>

drivers/leds/leds-lp5521.c

···
 	int ret;
 	struct lp55xx_chip *chip;
 	struct lp55xx_led *led;
-	struct lp55xx_platform_data *pdata;
+	struct lp55xx_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct device_node *np = client->dev.of_node;
 
-	if (!dev_get_platdata(&client->dev)) {
+	if (!pdata) {
 		if (np) {
-			ret = lp55xx_of_populate_pdata(&client->dev, np);
-			if (ret < 0)
-				return ret;
+			pdata = lp55xx_of_populate_pdata(&client->dev, np);
+			if (IS_ERR(pdata))
+				return PTR_ERR(pdata);
 		} else {
 			dev_err(&client->dev, "no platform data\n");
 			return -EINVAL;
 		}
 	}
-	pdata = dev_get_platdata(&client->dev);
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)

drivers/leds/leds-lp5523.c

···
 	int ret;
 	struct lp55xx_chip *chip;
 	struct lp55xx_led *led;
-	struct lp55xx_platform_data *pdata;
+	struct lp55xx_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct device_node *np = client->dev.of_node;
 
-	if (!dev_get_platdata(&client->dev)) {
+	if (!pdata) {
 		if (np) {
-			ret = lp55xx_of_populate_pdata(&client->dev, np);
-			if (ret < 0)
-				return ret;
+			pdata = lp55xx_of_populate_pdata(&client->dev, np);
+			if (IS_ERR(pdata))
+				return PTR_ERR(pdata);
 		} else {
 			dev_err(&client->dev, "no platform data\n");
 			return -EINVAL;
 		}
 	}
-	pdata = dev_get_platdata(&client->dev);
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)

drivers/leds/leds-lp5562.c

···
 	int ret;
 	struct lp55xx_chip *chip;
 	struct lp55xx_led *led;
-	struct lp55xx_platform_data *pdata;
+	struct lp55xx_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct device_node *np = client->dev.of_node;
 
-	if (!dev_get_platdata(&client->dev)) {
+	if (!pdata) {
 		if (np) {
-			ret = lp55xx_of_populate_pdata(&client->dev, np);
-			if (ret < 0)
-				return ret;
+			pdata = lp55xx_of_populate_pdata(&client->dev, np);
+			if (IS_ERR(pdata))
+				return PTR_ERR(pdata);
 		} else {
 			dev_err(&client->dev, "no platform data\n");
 			return -EINVAL;
 		}
 	}
-	pdata = dev_get_platdata(&client->dev);
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)

drivers/leds/leds-lp55xx-common.c

···
 }
 EXPORT_SYMBOL_GPL(lp55xx_unregister_sysfs);
 
-int lp55xx_of_populate_pdata(struct device *dev, struct device_node *np)
+struct lp55xx_platform_data *lp55xx_of_populate_pdata(struct device *dev,
+						      struct device_node *np)
 {
 	struct device_node *child;
 	struct lp55xx_platform_data *pdata;
···
 
 	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
 	if (!pdata)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	num_channels = of_get_child_count(np);
 	if (num_channels == 0) {
 		dev_err(dev, "no LED channels\n");
-		return -EINVAL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	cfg = devm_kzalloc(dev, sizeof(*cfg) * num_channels, GFP_KERNEL);
 	if (!cfg)
-		return -ENOMEM;
+		return ERR_PTR(-ENOMEM);
 
 	pdata->led_config = &cfg[0];
 	pdata->num_channels = num_channels;
···
 	/* LP8501 specific */
 	of_property_read_u8(np, "pwr-sel", (u8 *)&pdata->pwr_sel);
 
-	dev->platform_data = pdata;
-
-	return 0;
+	return pdata;
 }
 EXPORT_SYMBOL_GPL(lp55xx_of_populate_pdata);
 

drivers/leds/leds-lp55xx-common.h

···
 extern void lp55xx_unregister_sysfs(struct lp55xx_chip *chip);
 
 /* common device tree population function */
-extern int lp55xx_of_populate_pdata(struct device *dev,
-				    struct device_node *np);
+extern struct lp55xx_platform_data
+*lp55xx_of_populate_pdata(struct device *dev, struct device_node *np);
 
 #endif /* _LEDS_LP55XX_COMMON_H */

drivers/leds/leds-lp8501.c

···
 	int ret;
 	struct lp55xx_chip *chip;
 	struct lp55xx_led *led;
-	struct lp55xx_platform_data *pdata;
+	struct lp55xx_platform_data *pdata = dev_get_platdata(&client->dev);
 	struct device_node *np = client->dev.of_node;
 
-	if (!dev_get_platdata(&client->dev)) {
+	if (!pdata) {
 		if (np) {
-			ret = lp55xx_of_populate_pdata(&client->dev, np);
-			if (ret < 0)
-				return ret;
+			pdata = lp55xx_of_populate_pdata(&client->dev, np);
+			if (IS_ERR(pdata))
+				return PTR_ERR(pdata);
 		} else {
 			dev_err(&client->dev, "no platform data\n");
 			return -EINVAL;
 		}
 	}
-	pdata = dev_get_platdata(&client->dev);
 
 	chip = devm_kzalloc(&client->dev, sizeof(*chip), GFP_KERNEL);
 	if (!chip)