[PATCH v4 0/3] backlight: lm3630a: bug fix and fwnode support

[PATCH v4 0/3] backlight: lm3630a: bug fix and fwnode support

[Brian Masney]

Here is a patch series that fixes a single bug and adds fwnode support
to the lm3630a driver. This work was tested on a LG Nexus 5 (hammerhead)
phone. My status page at https://masneyb.github.io/nexus-5-upstream/
describes what is working so far with the upstream kernel.

See the individual patches for the changelog.

Brian Masney (3):
  backlight: lm3630a: return 0 on success in update_status functions
  dt-bindings: backlight: add lm3630a bindings
  backlight: lm3630a: add firmware node support

 .../leds/backlight/lm3630a-backlight.yaml     | 128 +++++++++++++++
 drivers/video/backlight/lm3630a_bl.c          | 151 +++++++++++++++++-
 include/linux/platform_data/lm3630a_bl.h      |   4 +
 3 files changed, 276 insertions(+), 7 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml

-- 
2.20.1

[PATCH v4 1/3] backlight: lm3630a: return 0 on success in update_status functions

[Brian Masney]

lm3630a_bank_a_update_status() and lm3630a_bank_b_update_status()
both return the brightness value if the brightness was successfully
updated. Writing to these attributes via sysfs would cause a 'Bad
address' error to be returned. These functions should return 0 on
success, so let's change it to correct that error.

Signed-off-by: Brian Masney <masneyb@onstation.org>
Fixes: 28e64a68a2ef ("backlight: lm3630: apply chip revision")
Acked-by: Pavel Machek <pavel@ucw.cz>
---
Changes since v3:
- None

Changes since v2:
- None

 drivers/video/backlight/lm3630a_bl.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index 2030a6b77a09..ef2553f452ca 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c
@@ -201,7 +201,7 @@ static int lm3630a_bank_a_update_status(struct backlight_device *bl)
 				      LM3630A_LEDA_ENABLE, LM3630A_LEDA_ENABLE);
 	if (ret < 0)
 		goto out_i2c_err;
-	return bl->props.brightness;
+	return 0;
 
 out_i2c_err:
 	dev_err(pchip->dev, "i2c failed to access\n");
@@ -278,7 +278,7 @@ static int lm3630a_bank_b_update_status(struct backlight_device *bl)
 				      LM3630A_LEDB_ENABLE, LM3630A_LEDB_ENABLE);
 	if (ret < 0)
 		goto out_i2c_err;
-	return bl->props.brightness;
+	return 0;
 
 out_i2c_err:
 	dev_err(pchip->dev, "i2c failed to access REG_CTRL\n");
-- 
2.20.1

[PATCH v4 2/3] dt-bindings: backlight: add lm3630a bindings

[Brian Masney]

Add new backlight bindings for the TI LM3630A dual-string white LED.

Signed-off-by: Brian Masney <masneyb@onstation.org>
---
Rob: Since the common bindings aren't converted to the new JSON schema
yet, I'm not sure how to do led-sources here. I would expect that we'd
have the uint32-array on the common binding once it exists. I had to
add it here to keep 'make dt_binding_check' happy. I left the
description off though for that property since that'll come from common
once its converted.

Changes since v3:
- Add label. I didn't add a description for it since that'll come from
  the common properties once its converted.

Changes since v2:
- Update description of max-brightness
- Add description for reg
- Correct typo: s/tranisiton/transition
- add reg to control banks
- add additionalProperties

 .../leds/backlight/lm3630a-backlight.yaml     | 128 ++++++++++++++++++
 1 file changed, 128 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml

diff --git a/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
new file mode 100644
index 000000000000..5067038ca637
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
@@ -0,0 +1,128 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/lm3630a-backlight.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI LM3630A High-Efficiency Dual-String White LED
+
+maintainers:
+  - Lee Jones <lee.jones@linaro.org>
+  - Daniel Thompson <daniel.thompson@linaro.org>
+  - Jingoo Han <jingoohan1@gmail.com>
+
+description: |
+  The LM3630A is a current-mode boost converter which supplies the power and
+  controls the current in up to two strings of 10 LEDs per string.
+  https://www.ti.com/product/LM3630A
+
+properties:
+  compatible:
+    const: ti,lm3630a
+
+  reg:
+    description: The I2C address of the device
+    maxItems: 1
+
+  ti,linear-mapping-mode:
+    description: |
+      Enable linear mapping mode. If disabled, then it will use exponential
+      mapping mode in which the ramp up/down appears to have a more uniform
+      transition to the human eye.
+    type: boolean
+
+required:
+  - compatible
+  - reg
+
+patternProperties:
+  "^led@[01]$":
+    type: object
+    description: |
+      Properties for a string of connected LEDs.
+
+    properties:
+      reg:
+        description: Control Bank
+        maxItems: 1
+        minimum: 0
+        maximum: 1
+
+      label:
+        maxItems: 1
+
+      led-sources:
+        allOf:
+          - $ref: /schemas/types.yaml#/definitions/uint32-array
+          - minItems: 1
+            maxItems: 2
+            items:
+              minimum: 0
+              maximum: 1
+
+      default-brightness:
+        description: Default brightness level on boot.
+        minimum: 0
+        maximum: 255
+
+      max-brightness:
+        description: Maximum brightness that is allowed during runtime.
+        minimum: 0
+        maximum: 255
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        lm3630a_bl@38 {
+                compatible = "ti,lm3630a";
+                status = "ok";
+                reg = <0x38>;
+
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                led@0 {
+                        reg = <0>;
+                        led-sources = <0 1>;
+                        label = "lcd-backlight";
+                        default-brightness = <200>;
+                        max-brightness = <255>;
+                };
+        };
+    };
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        lm3630a_bl@38 {
+                compatible = "ti,lm3630a";
+                status = "ok";
+                reg = <0x38>;
+
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                led@0 {
+                        reg = <0>;
+                        default-brightness = <150>;
+                        ti,linear-mapping-mode;
+                };
+
+                led@1 {
+                        reg = <1>;
+                        default-brightness = <225>;
+                        ti,linear-mapping-mode;
+                };
+        };
+    };
-- 
2.20.1

Re: [PATCH v4 2/3] dt-bindings: backlight: add lm3630a bindings

[Rob Herring]

On Tue, Apr 16, 2019 at 6:54 PM Brian Masney <masneyb@onstation.org> wrote:
>
> Add new backlight bindings for the TI LM3630A dual-string white LED.
>
> Signed-off-by: Brian Masney <masneyb@onstation.org>
> ---
> Rob: Since the common bindings aren't converted to the new JSON schema
> yet, I'm not sure how to do led-sources here. I would expect that we'd
> have the uint32-array on the common binding once it exists. I had to
> add it here to keep 'make dt_binding_check' happy. I left the
> description off though for that property since that'll come from common
> once its converted.

What was the error? '$ref' shouldn't be needed for this. The tooling
has no knowledge whether there's common schema or not. So you probably
have some pattern the meta-schema doesn't like and we need to fix.

>
> Changes since v3:
> - Add label. I didn't add a description for it since that'll come from
>   the common properties once its converted.
>
> Changes since v2:
> - Update description of max-brightness
> - Add description for reg
> - Correct typo: s/tranisiton/transition
> - add reg to control banks
> - add additionalProperties
>
>  .../leds/backlight/lm3630a-backlight.yaml     | 128 ++++++++++++++++++
>  1 file changed, 128 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
> new file mode 100644
> index 000000000000..5067038ca637
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/lm3630a-backlight.yaml
> @@ -0,0 +1,128 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/lm3630a-backlight.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: TI LM3630A High-Efficiency Dual-String White LED
> +
> +maintainers:
> +  - Lee Jones <lee.jones@linaro.org>
> +  - Daniel Thompson <daniel.thompson@linaro.org>
> +  - Jingoo Han <jingoohan1@gmail.com>
> +
> +description: |
> +  The LM3630A is a current-mode boost converter which supplies the power and
> +  controls the current in up to two strings of 10 LEDs per string.
> +  https://www.ti.com/product/LM3630A
> +
> +properties:
> +  compatible:
> +    const: ti,lm3630a
> +
> +  reg:
> +    description: The I2C address of the device

No need to describe a common property if there's nothing specific for
this device.

> +    maxItems: 1
> +
> +  ti,linear-mapping-mode:
> +    description: |
> +      Enable linear mapping mode. If disabled, then it will use exponential
> +      mapping mode in which the ramp up/down appears to have a more uniform
> +      transition to the human eye.
> +    type: boolean
> +
> +required:
> +  - compatible
> +  - reg
> +
> +patternProperties:
> +  "^led@[01]$":
> +    type: object
> +    description: |
> +      Properties for a string of connected LEDs.
> +
> +    properties:
> +      reg:
> +        description: Control Bank

Probably makes sense to have description here since this isn't a
standard type of address.

> +        maxItems: 1
> +        minimum: 0
> +        maximum: 1
> +
> +      label:
> +        maxItems: 1
> +
> +      led-sources:
> +        allOf:
> +          - $ref: /schemas/types.yaml#/definitions/uint32-array
> +          - minItems: 1
> +            maxItems: 2
> +            items:
> +              minimum: 0
> +              maximum: 1
> +
> +      default-brightness:
> +        description: Default brightness level on boot.
> +        minimum: 0
> +        maximum: 255
> +
> +      max-brightness:
> +        description: Maximum brightness that is allowed during runtime.
> +        minimum: 0
> +        maximum: 255
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        lm3630a_bl@38 {

led-controller@38

> +                compatible = "ti,lm3630a";
> +                status = "ok";

Don't show status in examples.

> +                reg = <0x38>;
> +
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                led@0 {
> +                        reg = <0>;
> +                        led-sources = <0 1>;
> +                        label = "lcd-backlight";
> +                        default-brightness = <200>;
> +                        max-brightness = <255>;
> +                };
> +        };
> +    };
> +  - |
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        lm3630a_bl@38 {
> +                compatible = "ti,lm3630a";
> +                status = "ok";
> +                reg = <0x38>;
> +
> +                #address-cells = <1>;
> +                #size-cells = <0>;
> +
> +                led@0 {
> +                        reg = <0>;
> +                        default-brightness = <150>;
> +                        ti,linear-mapping-mode;
> +                };
> +
> +                led@1 {
> +                        reg = <1>;
> +                        default-brightness = <225>;
> +                        ti,linear-mapping-mode;
> +                };
> +        };
> +    };
> --
> 2.20.1
>

Re: [PATCH v4 2/3] dt-bindings: backlight: add lm3630a bindings

[Brian Masney]

On Wed, Apr 17, 2019 at 08:34:33AM -0500, Rob Herring wrote:
> On Tue, Apr 16, 2019 at 6:54 PM Brian Masney <masneyb@onstation.org> wrote:
> >
> > Add new backlight bindings for the TI LM3630A dual-string white LED.
> >
> > Signed-off-by: Brian Masney <masneyb@onstation.org>
> > ---
> > Rob: Since the common bindings aren't converted to the new JSON schema
> > yet, I'm not sure how to do led-sources here. I would expect that we'd
> > have the uint32-array on the common binding once it exists. I had to
> > add it here to keep 'make dt_binding_check' happy. I left the
> > description off though for that property since that'll come from common
> > once its converted.
> 
> What was the error? '$ref' shouldn't be needed for this. The tooling
> has no knowledge whether there's common schema or not. So you probably
> have some pattern the meta-schema doesn't like and we need to fix.

Ahh, you're right... it works without the $ref. I just needed the
minItems and maxItems to fix the error I originally saw.

I'll wait for feedback from Dan before I send out another version with
your changes.

Thanks,

Brian

[PATCH v4 3/3] backlight: lm3630a: add firmware node support

[Brian Masney]

Add fwnode support to the lm3630a driver and optionally allow
configuring the label, default brightness level, and maximum brightness
level. The two outputs can be controlled by bank A and B independently
or bank A can control both outputs.

If the platform data was not configured, then the driver defaults to
enabling both banks. This patch changes the default value to disable
both banks before parsing the firmware node so that just a single bank
can be enabled if desired. There are no in-tree users of this driver.

Driver was tested on a LG Nexus 5 (hammerhead) phone.

Signed-off-by: Brian Masney <masneyb@onstation.org>
---
Changes since v3
- Add support for label
- Changed lm3630a_parse_node() to return -ENODEV if no nodes were found
- Remove LM3630A_LED{A,B}_DISABLE
- Add two additional newlines for code readability
- Remove extra newline

Changes since v2
- Separated out control banks and outputs via the reg and led-sources
  properties.
- Use fwnode instead of of API
- Disable both banks by default before calling lm3630a_parse_node()
- Add lots of error handling
- Check for duplicate source / bank definitions
- Remove extra ;
- Make probe() method fail if fwnode parsing fails.

 drivers/video/backlight/lm3630a_bl.c     | 147 ++++++++++++++++++++++-
 include/linux/platform_data/lm3630a_bl.h |   4 +
 2 files changed, 146 insertions(+), 5 deletions(-)

diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
index ef2553f452ca..6d3c54bfbb10 100644
--- a/drivers/video/backlight/lm3630a_bl.c
+++ b/drivers/video/backlight/lm3630a_bl.c
@@ -329,15 +329,17 @@ static const struct backlight_ops lm3630a_bank_b_ops = {
 
 static int lm3630a_backlight_register(struct lm3630a_chip *pchip)
 {
-	struct backlight_properties props;
 	struct lm3630a_platform_data *pdata = pchip->pdata;
+	struct backlight_properties props;
+	const char *label;
 
 	props.type = BACKLIGHT_RAW;
 	if (pdata->leda_ctrl != LM3630A_LEDA_DISABLE) {
 		props.brightness = pdata->leda_init_brt;
 		props.max_brightness = pdata->leda_max_brt;
+		label = pdata->leda_label ? pdata->leda_label : "lm3630a_leda";
 		pchip->bleda -		    devm_backlight_device_register(pchip->dev, "lm3630a_leda",
+		    devm_backlight_device_register(pchip->dev, label,
 						   pchip->dev, pchip,
 						   &lm3630a_bank_a_ops, &props);
 		if (IS_ERR(pchip->bleda))
@@ -348,8 +350,9 @@ static int lm3630a_backlight_register(struct lm3630a_chip *pchip)
 	    (pdata->ledb_ctrl != LM3630A_LEDB_ON_A)) {
 		props.brightness = pdata->ledb_init_brt;
 		props.max_brightness = pdata->ledb_max_brt;
+		label = pdata->ledb_label ? pdata->ledb_label : "lm3630a_ledb";
 		pchip->bledb -		    devm_backlight_device_register(pchip->dev, "lm3630a_ledb",
+		    devm_backlight_device_register(pchip->dev, label,
 						   pchip->dev, pchip,
 						   &lm3630a_bank_b_ops, &props);
 		if (IS_ERR(pchip->bledb))
@@ -364,6 +367,129 @@ static const struct regmap_config lm3630a_regmap = {
 	.max_register = REG_MAX,
 };
 
+/**
+ * lm3630a_parse_led_sources - Parse the optional led-sources fwnode property.
+ * @node: firmware node
+ * @default_bitmask: bitmask to return if the led-sources property was not
+ *                   specified
+ *
+ * Parses the optional led-sources firmware node and returns a bitmask that
+ * contains the outputs that are associated with the control bank. If the
+ * property is missing, then the value of of @default_bitmask will be returned.
+ */
+static int lm3630a_parse_led_sources(struct fwnode_handle *node,
+				     int default_bitmask)
+{
+	int ret, num_sources, i;
+	u32 sources[2];
+
+	num_sources = fwnode_property_read_u32_array(node, "led-sources", NULL,
+						     0);
+	if (num_sources < 0)
+		return default_bitmask;
+	else if (num_sources > ARRAY_SIZE(sources))
+		return -EINVAL;
+
+	ret = fwnode_property_read_u32_array(node, "led-sources", sources,
+					     num_sources);
+	if (ret)
+		return ret;
+
+	ret = 0;
+	for (i = 0; i < num_sources; i++) {
+		if (sources[i] < 0 || sources[i] > 1)
+			return -EINVAL;
+
+		ret |= BIT(sources[i]);
+	}
+
+	return ret;
+}
+
+static int lm3630a_parse_node(struct lm3630a_chip *pchip,
+			      struct lm3630a_platform_data *pdata)
+{
+	int led_sources, ret = -ENODEV, seen = 0;
+	struct fwnode_handle *node;
+	const char *label;
+	u32 bank, val;
+	bool linear;
+
+	device_for_each_child_node(pchip->dev, node) {
+		ret = fwnode_property_read_u32(node, "reg", &bank);
+		if (ret < 0)
+			return ret;
+
+		if (bank < 0 || bank > 1)
+			return -EINVAL;
+
+		if (seen & BIT(bank))
+			return -EINVAL;
+
+		seen |= BIT(bank);
+
+		led_sources = lm3630a_parse_led_sources(node, BIT(bank));
+		if (led_sources < 0)
+			return led_sources;
+
+		linear = fwnode_property_read_bool(node,
+						   "ti,linear-mapping-mode");
+		if (bank = 0) {
+			if (!(led_sources & BIT(0)))
+				return -EINVAL;
+
+			pdata->leda_ctrl = linear ?
+				LM3630A_LEDA_ENABLE_LINEAR :
+				LM3630A_LEDA_ENABLE;
+
+			if (led_sources & BIT(1)) {
+				if (seen & BIT(1))
+					return -EINVAL;
+
+				seen |= BIT(1);
+
+				pdata->ledb_ctrl = LM3630A_LEDB_ON_A;
+			}
+		} else {
+			if (led_sources & BIT(0) || !(led_sources & BIT(1)))
+				return -EINVAL;
+
+			pdata->ledb_ctrl = linear ?
+				LM3630A_LEDB_ENABLE_LINEAR :
+				LM3630A_LEDB_ENABLE;
+		}
+
+		ret = fwnode_property_read_string(node, "label", &label);
+		if (!ret) {
+			if (bank = 0)
+				pdata->leda_label = label;
+			else
+				pdata->ledb_label = label;
+		}
+
+		ret = fwnode_property_read_u32(node, "default-brightness",
+					       &val);
+		if (!ret) {
+			if (bank = 0)
+				pdata->leda_init_brt = val;
+			else
+				pdata->ledb_init_brt = val;
+		}
+
+		ret = fwnode_property_read_u32(node, "max-brightness", &val);
+		if (!ret) {
+			if (bank = 0)
+				pdata->leda_max_brt = val;
+			else
+				pdata->ledb_max_brt = val;
+		}
+
+		ret = 0;
+	}
+
+	return ret;
+}
+
 static int lm3630a_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
 {
@@ -396,13 +522,18 @@ static int lm3630a_probe(struct i2c_client *client,
 				     GFP_KERNEL);
 		if (pdata = NULL)
 			return -ENOMEM;
+
 		/* default values */
-		pdata->leda_ctrl = LM3630A_LEDA_ENABLE;
-		pdata->ledb_ctrl = LM3630A_LEDB_ENABLE;
 		pdata->leda_max_brt = LM3630A_MAX_BRIGHTNESS;
 		pdata->ledb_max_brt = LM3630A_MAX_BRIGHTNESS;
 		pdata->leda_init_brt = LM3630A_MAX_BRIGHTNESS;
 		pdata->ledb_init_brt = LM3630A_MAX_BRIGHTNESS;
+
+		rval = lm3630a_parse_node(pchip, pdata);
+		if (rval) {
+			dev_err(&client->dev, "fail : parse node\n");
+			return rval;
+		}
 	}
 	pchip->pdata = pdata;
 
@@ -470,11 +601,17 @@ static const struct i2c_device_id lm3630a_id[] = {
 	{}
 };
 
+static const struct of_device_id lm3630a_match_table[] = {
+	{ .compatible = "ti,lm3630a", },
+	{ },
+};
+
 MODULE_DEVICE_TABLE(i2c, lm3630a_id);
 
 static struct i2c_driver lm3630a_i2c_driver = {
 	.driver = {
 		   .name = LM3630A_NAME,
+		   .of_match_table = lm3630a_match_table,
 		   },
 	.probe = lm3630a_probe,
 	.remove = lm3630a_remove,
diff --git a/include/linux/platform_data/lm3630a_bl.h b/include/linux/platform_data/lm3630a_bl.h
index 7538e38e270b..762e68956f31 100644
--- a/include/linux/platform_data/lm3630a_bl.h
+++ b/include/linux/platform_data/lm3630a_bl.h
@@ -38,9 +38,11 @@ enum lm3630a_ledb_ctrl {
 
 #define LM3630A_MAX_BRIGHTNESS 255
 /*
+ *@leda_label    : optional led a label.
  *@leda_init_brt : led a init brightness. 4~255
  *@leda_max_brt  : led a max brightness.  4~255
  *@leda_ctrl     : led a disable, enable linear, enable exponential
+ *@ledb_label    : optional led b label.
  *@ledb_init_brt : led b init brightness. 4~255
  *@ledb_max_brt  : led b max brightness.  4~255
  *@ledb_ctrl     : led b disable, enable linear, enable exponential
@@ -50,10 +52,12 @@ enum lm3630a_ledb_ctrl {
 struct lm3630a_platform_data {
 
 	/* led a config.  */
+	const char *leda_label;
 	int leda_init_brt;
 	int leda_max_brt;
 	enum lm3630a_leda_ctrl leda_ctrl;
 	/* led b config. */
+	const char *ledb_label;
 	int ledb_init_brt;
 	int ledb_max_brt;
 	enum lm3630a_ledb_ctrl ledb_ctrl;
-- 
2.20.1

Re: [PATCH v4 3/3] backlight: lm3630a: add firmware node support

[Dan Murphy]

Brian

On 4/16/19 6:53 PM, Brian Masney wrote:
> Add fwnode support to the lm3630a driver and optionally allow
> configuring the label, default brightness level, and maximum brightness
> level. The two outputs can be controlled by bank A and B independently
> or bank A can control both outputs.
> 
> If the platform data was not configured, then the driver defaults to
> enabling both banks. This patch changes the default value to disable
> both banks before parsing the firmware node so that just a single bank
> can be enabled if desired. There are no in-tree users of this driver.
> 
> Driver was tested on a LG Nexus 5 (hammerhead) phone.
> 
> Signed-off-by: Brian Masney <masneyb@onstation.org>
> ---
> Changes since v3
> - Add support for label
> - Changed lm3630a_parse_node() to return -ENODEV if no nodes were found
> - Remove LM3630A_LED{A,B}_DISABLE
> - Add two additional newlines for code readability
> - Remove extra newline
> 
> Changes since v2
> - Separated out control banks and outputs via the reg and led-sources
>   properties.
> - Use fwnode instead of of API
> - Disable both banks by default before calling lm3630a_parse_node()
> - Add lots of error handling
> - Check for duplicate source / bank definitions
> - Remove extra ;
> - Make probe() method fail if fwnode parsing fails.
> 
>  drivers/video/backlight/lm3630a_bl.c     | 147 ++++++++++++++++++++++-
>  include/linux/platform_data/lm3630a_bl.h |   4 +
>  2 files changed, 146 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/video/backlight/lm3630a_bl.c b/drivers/video/backlight/lm3630a_bl.c
> index ef2553f452ca..6d3c54bfbb10 100644
> --- a/drivers/video/backlight/lm3630a_bl.c
> +++ b/drivers/video/backlight/lm3630a_bl.c
> @@ -329,15 +329,17 @@ static const struct backlight_ops lm3630a_bank_b_ops = {
>  
>  static int lm3630a_backlight_register(struct lm3630a_chip *pchip)
>  {
> -	struct backlight_properties props;
>  	struct lm3630a_platform_data *pdata = pchip->pdata;
> +	struct backlight_properties props;
> +	const char *label;
>  
>  	props.type = BACKLIGHT_RAW;
>  	if (pdata->leda_ctrl != LM3630A_LEDA_DISABLE) {
>  		props.brightness = pdata->leda_init_brt;
>  		props.max_brightness = pdata->leda_max_brt;
> +		label = pdata->leda_label ? pdata->leda_label : "lm3630a_leda";
>  		pchip->bleda > -		    devm_backlight_device_register(pchip->dev, "lm3630a_leda",
> +		    devm_backlight_device_register(pchip->dev, label,
>  						   pchip->dev, pchip,
>  						   &lm3630a_bank_a_ops, &props);
>  		if (IS_ERR(pchip->bleda))
> @@ -348,8 +350,9 @@ static int lm3630a_backlight_register(struct lm3630a_chip *pchip)
>  	    (pdata->ledb_ctrl != LM3630A_LEDB_ON_A)) {
>  		props.brightness = pdata->ledb_init_brt;
>  		props.max_brightness = pdata->ledb_max_brt;
> +		label = pdata->ledb_label ? pdata->ledb_label : "lm3630a_ledb";
>  		pchip->bledb > -		    devm_backlight_device_register(pchip->dev, "lm3630a_ledb",
> +		    devm_backlight_device_register(pchip->dev, label,
>  						   pchip->dev, pchip,
>  						   &lm3630a_bank_b_ops, &props);
>  		if (IS_ERR(pchip->bledb))
> @@ -364,6 +367,129 @@ static const struct regmap_config lm3630a_regmap = {
>  	.max_register = REG_MAX,
>  };
>  
> +/**
> + * lm3630a_parse_led_sources - Parse the optional led-sources fwnode property.
> + * @node: firmware node
> + * @default_bitmask: bitmask to return if the led-sources property was not
> + *                   specified
> + *
> + * Parses the optional led-sources firmware node and returns a bitmask that
> + * contains the outputs that are associated with the control bank. If the
> + * property is missing, then the value of of @default_bitmask will be returned.
> + */

Not sure if this was intentional but you documented this interface you added but the others
you did not.  If you need to explain what this is doing then the code may not be clear or the DT
doc is not explicit enough.

> +static int lm3630a_parse_led_sources(struct fwnode_handle *node,
> +				     int default_bitmask)
> +{
> +	int ret, num_sources, i;
> +	u32 sources[2];
> +
> +	num_sources = fwnode_property_read_u32_array(node, "led-sources", NULL,
> +						     0);
> +	if (num_sources < 0)
> +		return default_bitmask;
> +	else if (num_sources > ARRAY_SIZE(sources))
> +		return -EINVAL;
> +
> +	ret = fwnode_property_read_u32_array(node, "led-sources", sources,
> +					     num_sources);
> +	if (ret)
> +		return ret;
> +
> +	ret = 0;

This is unneeded since fwnode should return 0 on success if it gets here

> +	for (i = 0; i < num_sources; i++) {
> +		if (sources[i] < 0 || sources[i] > 1)
> +			return -EINVAL;
> +
> +		ret |= BIT(sources[i]);
> +	}
> +
> +	return ret;
> +}
> +
> +static int lm3630a_parse_node(struct lm3630a_chip *pchip,
> +			      struct lm3630a_platform_data *pdata)
> +{
> +	int led_sources, ret = -ENODEV, seen = 0;
> +	struct fwnode_handle *node;
> +	const char *label;
> +	u32 bank, val;
> +	bool linear;
> +
> +	device_for_each_child_node(pchip->dev, node) {
> +		ret = fwnode_property_read_u32(node, "reg", &bank);
> +		if (ret < 0)

if (ret) should be fine here.

> +			return ret;
> +
> +		if (bank < 0 || bank > 1)

maybe define the banks 

#define LM3630A_BANK_0	0
#define LM3630A_BANK_1	1

So it is clear in the code what are the limits to the condition.

if (bank < LM3630A_BANK_0 || bank > LM3630A_BANK_1)

> +			return -EINVAL;
> +
> +		if (seen & BIT(bank))
> +			return -EINVAL;
> +
> +		seen |= BIT(bank);
> +
> +		led_sources = lm3630a_parse_led_sources(node, BIT(bank));
> +		if (led_sources < 0)
> +			return led_sources;
> +
> +		linear = fwnode_property_read_bool(node,
> +						   "ti,linear-mapping-mode");
> +		if (bank = 0) {

This may be nitpicky but what if you flip the if..else and do
You have already validated bank to be within range.

if(bank)
	ledb work
else
	leda work

> +			if (!(led_sources & BIT(0)))
> +				return -EINVAL;
> +
> +			pdata->leda_ctrl = linear ?
> +				LM3630A_LEDA_ENABLE_LINEAR :
> +				LM3630A_LEDA_ENABLE;
> +
> +			if (led_sources & BIT(1)) {
> +				if (seen & BIT(1))
> +					return -EINVAL;
> +
> +				seen |= BIT(1);
> +
> +				pdata->ledb_ctrl = LM3630A_LEDB_ON_A;
> +			}
> +		} else {
> +			if (led_sources & BIT(0) || !(led_sources & BIT(1)))
> +				return -EINVAL;
> +
> +			pdata->ledb_ctrl = linear ?
> +				LM3630A_LEDB_ENABLE_LINEAR :
> +				LM3630A_LEDB_ENABLE;
> +		}
> +
> +		ret = fwnode_property_read_string(node, "label", &label);
> +		if (!ret) {
> +			if (bank = 0)
> +				pdata->leda_label = label;
> +			else
> +				pdata->ledb_label = label;
> +		}
> +
> +		ret = fwnode_property_read_u32(node, "default-brightness",
> +					       &val);
> +		if (!ret) {
> +			if (bank = 0)
> +				pdata->leda_init_brt = val;
> +			else
> +				pdata->ledb_init_brt = val;
> +		}
> +
> +		ret = fwnode_property_read_u32(node, "max-brightness", &val);
> +		if (!ret) {
> +			if (bank = 0)
> +				pdata->leda_max_brt = val;
> +			else
> +				pdata->ledb_max_brt = val;
> +		}
> +
> +		ret = 0;

Maybe this could be

if (ret)
	ret = 0;
else
	do bank work.

Dan

<snip>