[PATCH v4 0/4] backlight: add new max25014 backlight driver

[PATCH v4 0/4] backlight: add new max25014 backlight driver

[Maud Spierings via B4 Relay]

The Maxim MAX25014 is an automotive grade backlight driver IC. Its
datasheet can be found at [1].

With its integrated boost controller, it can power 4 channels (led
strings) and has a number of different modes using pwm and or i2c.
Currently implemented is only i2c control.

link: https://www.analog.com/media/en/technical-documentation/data-sheets/MAX25014.pdf [1]

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
Changes in v4:
- use a led node to describe the backlight
- use led-sources to enable specific channels
- also wait 2ms when there is a supply but no enable
- change dev_warn() to dev_err() in error path in max25014_check_errors()
- set backlight_properties.scale to BACKLIGHT_SCALE_LINEAR
- rebase latest next
- add address-cells and size-cells to i2c4 in av101hdt-a10.dtso
- Link to v3: https://lore.kernel.org/r/20250911-max25014-v3-0-d03f4eba375e@gocontroll.com

Changes in v3:
- fixed commit message type intgrated -> integrated
- added maximum and description to maxim,iset-property
- dropped unused labels and pinctrl in bindings example
- put the compatible first in the bindings example and dts
- removed brackets around defines
- removed the leftover pdata struct field
- removed the initial_brightness struct field
- Link to v2: https://lore.kernel.org/r/20250819-max25014-v2-0-5fd7aeb141ea@gocontroll.com

Changes in v2:
- Remove leftover unused property from the bindings example
- Complete the bindings example with all properties
- Remove some double info from the maxim,iset property
- Remove platform_data header, fold its data into the max25014 struct
- Don't force defines to be unsigned
- Remove stray struct max25014 declaration
- Remove chipname and device from the max25014 struct
- Inline the max25014_backlight_register() and strings_mask() functions
- Remove CONFIG_OF ifdef
- Link to v1: https://lore.kernel.org/r/20250725-max25014-v1-0-0e8cce92078e@gocontroll.com

---
Maud Spierings (4):
      dt-bindings: backlight: Add max25014 bindings
      backlight: add max25014atg backlight
      arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight
      arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight

 .../bindings/leds/backlight/maxim,max25014.yaml    | 109 ++++++
 MAINTAINERS                                        |   6 +
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso |  32 ++
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso |  27 +-
 drivers/video/backlight/Kconfig                    |   7 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/max25014.c                 | 409 +++++++++++++++++++++
 7 files changed, 590 insertions(+), 1 deletion(-)
---
base-commit: 7c3ba4249a3604477ea9c077e10089ba7ddcaa03
change-id: 20250626-max25014-4207591e1af5

Best regards,
-- 
Maud Spierings <maudspierings@gocontroll.com>

[PATCH v4 1/4] dt-bindings: backlight: Add max25014 bindings

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.

In the current implementation the control registers for channel 1,
control all channels. So only one led subnode with led-sources is
supported right now. If at some point the driver functionality is
expanded the bindings can be easily extended with it.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 .../bindings/leds/backlight/maxim,max25014.yaml    | 109 +++++++++++++++++++++
 MAINTAINERS                                        |   5 +
 2 files changed, 114 insertions(+)

diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
new file mode 100644
index 0000000000000..496520e1374e5
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
@@ -0,0 +1,109 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Maxim max25014 backlight controller
+
+maintainers:
+  - Maud Spierings <maudspierings@gocontroll.com>
+
+properties:
+  compatible:
+    enum:
+      - maxim,max25014
+
+  reg:
+    maxItems: 1
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 0
+
+  enable-gpios:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  power-supply:
+    description: Regulator which controls the boost converter input rail.
+
+  pwms:
+    maxItems: 1
+
+  maxim,iset:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    maximum: 15
+    default: 11
+    description:
+      Value of the ISET register field. This controls the current scale of the
+      outputs, a higher number means more current.
+
+patternProperties:
+  "^led@[01]$":
+    type: object
+    description: Properties for a string of connected LEDs.
+    $ref: common.yaml#
+
+    properties:
+      reg:
+        const: 0
+
+      led-sources:
+        allOf:
+          - minItems: 1
+            maxItems: 4
+            items:
+              minimum: 0
+              maximum: 3
+            default: [0, 1, 2, 3]
+
+      default-brightness:
+        minimum: 0
+        maximum: 100
+        default: 50
+
+    required:
+      - reg
+
+    additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        backlight@6f {
+            compatible = "maxim,max25014";
+            reg = <0x6f>;
+            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
+            power-supply = <&reg_backlight>;
+            pwms = <&pwm1>;
+            maxim,iset = <7>;
+
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            led@0 {
+                reg = <0>;
+                led-sources = <0 1 2 3>;
+                default-brightness = <50>;
+            };
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 47fbc5e06808f..be5e2515900ce 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15171,6 +15171,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
 F:	drivers/media/i2c/max2175*
 F:	include/uapi/linux/max2175.h
 
+MAX25014 BACKLIGHT DRIVER
+M:	Maud Spierings <maudspierings@gocontroll.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+
 MAX31335 RTC DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
 L:	linux-rtc@vger.kernel.org

-- 
2.51.0

[PATCH v4 2/4] backlight: add max25014atg backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
with integrated boost controller.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 MAINTAINERS                        |   1 +
 drivers/video/backlight/Kconfig    |   7 +
 drivers/video/backlight/Makefile   |   1 +
 drivers/video/backlight/max25014.c | 409 +++++++++++++++++++++++++++++++++++++
 4 files changed, 418 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index be5e2515900ce..77bb4fd3474e1 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15175,6 +15175,7 @@ MAX25014 BACKLIGHT DRIVER
 M:	Maud Spierings <maudspierings@gocontroll.com>
 S:	Maintained
 F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
+F:	drivers/video/backlight/max25014.c
 
 MAX31335 RTC DRIVER
 M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
diff --git a/drivers/video/backlight/Kconfig b/drivers/video/backlight/Kconfig
index d9374d208ceeb..d3bb6ccd41853 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -262,6 +262,13 @@ config BACKLIGHT_DA9052
 	help
 	  Enable the Backlight Driver for DA9052-BC and DA9053-AA/Bx PMICs.
 
+config BACKLIGHT_MAX25014
+	tristate "Backlight driver for the Maxim MAX25014 chip"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you are using a MAX25014 chip as a backlight driver say Y to enable it.
+
 config BACKLIGHT_MAX8925
 	tristate "Backlight driver for MAX8925"
 	depends on MFD_MAX8925
diff --git a/drivers/video/backlight/Makefile b/drivers/video/backlight/Makefile
index dfbb169bf6ea2..1170d9ec40b8d 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -45,6 +45,7 @@ obj-$(CONFIG_BACKLIGHT_LOCOMO)		+= locomolcd.o
 obj-$(CONFIG_BACKLIGHT_LP855X)		+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_LP8788)		+= lp8788_bl.o
 obj-$(CONFIG_BACKLIGHT_LV5207LP)	+= lv5207lp.o
+obj-$(CONFIG_BACKLIGHT_MAX25014)	+= max25014.o
 obj-$(CONFIG_BACKLIGHT_MAX8925)		+= max8925_bl.o
 obj-$(CONFIG_BACKLIGHT_MP3309C)		+= mp3309c.o
 obj-$(CONFIG_BACKLIGHT_MT6370)		+= mt6370-backlight.o
diff --git a/drivers/video/backlight/max25014.c b/drivers/video/backlight/max25014.c
new file mode 100644
index 0000000000000..36bae508697e8
--- /dev/null
+++ b/drivers/video/backlight/max25014.c
@@ -0,0 +1,409 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Backlight driver for Maxim MAX25014
+ *
+ * Copyright (C) 2025 GOcontroll B.V.
+ * Author: Maud Spierings <maudspierings@gocontroll.com>
+ */
+
+#include <linux/backlight.h>
+#include <linux/gpio/consumer.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define MAX25014_ISET_DEFAULT_100 11
+#define MAX_BRIGHTNESS            100
+#define MIN_BRIGHTNESS            0
+#define TON_MAX                   130720 /* @153Hz */
+#define TON_STEP                  1307 /* @153Hz */
+#define TON_MIN                   0
+
+#define MAX25014_DEV_ID           0x00
+#define MAX25014_REV_ID           0x01
+#define MAX25014_ISET             0x02
+#define MAX25014_IMODE            0x03
+#define MAX25014_TON1H            0x04
+#define MAX25014_TON1L            0x05
+#define MAX25014_TON2H            0x06
+#define MAX25014_TON2L            0x07
+#define MAX25014_TON3H            0x08
+#define MAX25014_TON3L            0x09
+#define MAX25014_TON4H            0x0A
+#define MAX25014_TON4L            0x0B
+#define MAX25014_TON_1_4_LSB      0x0C
+#define MAX25014_SETTING          0x12
+#define MAX25014_DISABLE          0x13
+#define MAX25014_BSTMON           0x14
+#define MAX25014_IOUT1            0x15
+#define MAX25014_IOUT2            0x16
+#define MAX25014_IOUT3            0x17
+#define MAX25014_IOUT4            0x18
+#define MAX25014_OPEN             0x1B
+#define MAX25014_SHORT_GND        0x1C
+#define MAX25014_SHORT_LED        0x1D
+#define MAX25014_MASK             0x1E
+#define MAX25014_DIAG             0x1F
+
+#define MAX25014_IMODE_HDIM       BIT(2)
+#define MAX25014_ISET_ENABLE      BIT(5)
+#define MAX25014_ISET_PSEN        BIT(4)
+#define MAX25014_DIAG_HW_RST      BIT(2)
+#define MAX25014_SETTING_FPWM     GENMASK(6, 4)
+
+struct max25014 {
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct regmap *regmap;
+	struct gpio_desc *enable;
+	struct regulator *vin; /* regulator for boost converter Vin rail */
+	uint32_t iset;
+	uint8_t strings_mask;
+};
+
+static const struct regmap_config max25014_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = MAX25014_DIAG,
+};
+
+/**
+ * @brief control the brightness with i2c registers
+ *
+ * @param regmap trivial
+ * @param brt brightness
+ * @return int
+ */
+static int max25014_register_control(struct regmap *regmap, uint32_t brt)
+{
+	uint32_t reg = TON_STEP * brt;
+	int ret;
+	/*
+	 * 18 bit number lowest, 2 bits in first register,
+	 * next lowest 8 in the L register, next 8 in the H register
+	 * Seemingly setting the strength of only one string controls all of
+	 * them, individual settings don't affect the outcome.
+	 */
+
+	ret = regmap_write(regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
+	if (ret != 0)
+		return ret;
+	ret = regmap_write(regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
+	if (ret != 0)
+		return ret;
+	return regmap_write(regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
+}
+
+static int max25014_check_errors(struct max25014 *maxim)
+{
+	uint8_t i;
+	int ret;
+	uint32_t val;
+
+	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
+	if (ret != 0)
+		return ret;
+	if (val > 0) {
+		dev_err(&maxim->client->dev, "Open led strings detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+	if (ret != 0)
+		return ret;
+	if (val > 0) {
+		dev_err(&maxim->client->dev, "Short to ground detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_SHORT_GND, &val);
+	if (ret != 0)
+		return ret;
+	if (val > 0) {
+		dev_err(&maxim->client->dev, "Shorted led detected on:\n");
+		for (i = 0; i < 4; i++) {
+			if (val & 1 << i)
+				dev_err(&maxim->client->dev, "string %d\n", i + 1);
+		}
+		return -EIO;
+	}
+
+	ret = regmap_read(maxim->regmap, MAX25014_DIAG, &val);
+	if (ret != 0)
+		return ret;
+	/*
+	 * The HW_RST bit always starts at 1 after power up.
+	 * It is reset on first read, does not indicate an error.
+	 */
+	if (val > 0 && val != MAX25014_DIAG_HW_RST) {
+		if (val & 0b1)
+			dev_err(&maxim->client->dev,
+				"Overtemperature shutdown\n");
+		if (val & 0b10)
+			dev_err(&maxim->client->dev,
+				 "Chip is getting too hot (>125C)\n");
+		if (val & 0b1000)
+			dev_err(&maxim->client->dev,
+				"Boost converter overvoltage\n");
+		if (val & 0b10000)
+			dev_err(&maxim->client->dev,
+				"Boost converter undervoltage\n");
+		if (val & 0b100000)
+			dev_err(&maxim->client->dev, "IREF out of range\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * 1. disable unused strings
+ * 2. set dim mode
+ * 3. set initial brightness
+ * 4. set setting register
+ * 5. enable the backlight
+ */
+static int max25014_configure(struct max25014 *maxim)
+{
+	int ret;
+	uint32_t val;
+
+	ret = regmap_write(maxim->regmap, MAX25014_DISABLE,
+			   maxim->strings_mask);
+	if (ret != 0)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
+	if (ret != 0)
+		return ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
+	if (ret != 0)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
+			   val & ~MAX25014_SETTING_FPWM);
+	if (ret != 0)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_ISET,
+			   maxim->iset | MAX25014_ISET_ENABLE |
+			   MAX25014_ISET_PSEN);
+	return ret;
+}
+
+static int max25014_update_status(struct backlight_device *bl_dev)
+{
+	struct max25014 *maxim = bl_get_data(bl_dev);
+
+	if (backlight_is_blank(maxim->bl))
+		bl_dev->props.brightness = 0;
+
+	return max25014_register_control(maxim->regmap,
+					 bl_dev->props.brightness);
+}
+
+static const struct backlight_ops max25014_bl_ops = {
+	.options = BL_CORE_SUSPENDRESUME,
+	.update_status = max25014_update_status,
+};
+
+static int max25014_parse_dt(struct max25014 *maxim,
+			     uint32_t *initial_brightness)
+{
+	struct device *dev = &maxim->client->dev;
+	struct device_node *node = dev->of_node;
+	struct fwnode_handle *child;
+	uint32_t strings[4];
+	int res, i;
+
+	if (!node) {
+		dev_err(dev, "no platform data\n");
+		return -EINVAL;
+	}
+
+	child = device_get_next_child_node(dev, NULL);
+	if (child) {
+		res = fwnode_property_count_u32(child, "led-sources");
+		if (res > 0) {
+			fwnode_property_read_u32_array(child, "led-sources",
+						       strings, res);
+
+			/* set all strings as disabled, then enable those in led-sources*/
+			maxim->strings_mask = 0xf;
+			for (i = 0; i < res; i++) {
+				if (strings[i] <= 4)
+					maxim->strings_mask &= ~BIT(strings[i]);
+			}
+		}
+
+		fwnode_property_read_u32(child, "default-brightness",
+					 initial_brightness);
+
+		fwnode_handle_put(child);
+	}
+
+	maxim->iset = MAX25014_ISET_DEFAULT_100;
+	of_property_read_u32(node, "maxim,iset", &maxim->iset);
+
+	if (maxim->iset < 0 || maxim->iset > 15) {
+		dev_err(dev,
+			"Invalid iset, should be a value from 0-15, entered was %d\n",
+			maxim->iset);
+		return -EINVAL;
+	}
+
+	if (*initial_brightness < 0 || *initial_brightness > 100) {
+		dev_err(dev,
+			"Invalid initial brightness, should be a value from 0-100, entered was %d\n",
+			*initial_brightness);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int max25014_probe(struct i2c_client *cl)
+{
+	struct backlight_device *bl;
+	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
+	struct max25014 *maxim;
+	struct backlight_properties props;
+	int ret;
+	uint32_t initial_brightness = 50;
+
+	maxim = devm_kzalloc(&cl->dev, sizeof(struct max25014), GFP_KERNEL);
+	if (!maxim)
+		return -ENOMEM;
+
+	maxim->client = cl;
+
+	ret = max25014_parse_dt(maxim, &initial_brightness);
+	if (ret < 0)
+		return ret;
+
+	maxim->vin = devm_regulator_get_optional(&maxim->client->dev, "power");
+	if (IS_ERR(maxim->vin)) {
+		if (PTR_ERR(maxim->vin) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		maxim->vin = NULL;
+	}
+
+	if (maxim->vin) {
+		ret = regulator_enable(maxim->vin);
+		if (ret < 0) {
+			dev_err(&maxim->client->dev,
+				"failed to enable Vin: %d\n", ret);
+			return ret;
+		}
+	}
+
+	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
+						GPIOD_ASIS);
+	if (IS_ERR(maxim->enable)) {
+		ret = PTR_ERR(maxim->enable);
+		dev_err(&maxim->client->dev, "failed to get enable gpio: %d\n",
+			ret);
+		goto disable_vin;
+	}
+
+	if (maxim->enable)
+		gpiod_set_value_cansleep(maxim->enable, 1);
+
+	/* Enable can be tied to vin rail wait if either is available */
+	if (maxim->enable || maxim->vin) {
+		/* Datasheet Electrical Characteristics tSTARTUP 2ms */
+		usleep_range(2000, 2500);
+	}
+
+	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
+	if (IS_ERR(maxim->regmap)) {
+		ret = PTR_ERR(maxim->regmap);
+		dev_err(&maxim->client->dev,
+			"failed to initialize the i2c regmap: %d\n", ret);
+		goto disable_full;
+	}
+
+	i2c_set_clientdata(cl, maxim);
+
+	ret = max25014_check_errors(maxim);
+	if (ret) { /* error is already reported in the above function */
+		goto disable_full;
+	}
+
+	ret = max25014_configure(maxim);
+	if (ret) {
+		dev_err(&maxim->client->dev, "device config err: %d", ret);
+		goto disable_full;
+	}
+
+	memset(&props, 0, sizeof(props));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+	props.brightness = initial_brightness;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+
+	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
+					    &maxim->client->dev, maxim,
+					    &max25014_bl_ops, &props);
+	if (IS_ERR(bl))
+		return PTR_ERR(bl);
+
+	maxim->bl = bl;
+
+	return 0;
+
+disable_full:
+	if (maxim->enable)
+		gpiod_set_value_cansleep(maxim->enable, 0);
+disable_vin:
+	if (maxim->vin)
+		regulator_disable(maxim->vin);
+	return ret;
+}
+
+static void max25014_remove(struct i2c_client *cl)
+{
+	struct max25014 *maxim = i2c_get_clientdata(cl);
+
+	maxim->bl->props.brightness = 0;
+	max25014_update_status(maxim->bl);
+	if (maxim->enable)
+		gpiod_set_value_cansleep(maxim->enable, 0);
+	if (maxim->vin)
+		regulator_disable(maxim->vin);
+}
+
+static const struct of_device_id max25014_dt_ids[] = {
+	{ .compatible = "maxim,max25014", },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, max25014_dt_ids);
+
+static const struct i2c_device_id max25014_ids[] = {
+	{ "max25014" },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, max25014_ids);
+
+static struct i2c_driver max25014_driver = {
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = of_match_ptr(max25014_dt_ids),
+	},
+	.probe = max25014_probe,
+	.remove = max25014_remove,
+	.id_table = max25014_ids,
+};
+module_i2c_driver(max25014_driver);
+
+MODULE_DESCRIPTION("Maxim MAX25014 backlight driver");
+MODULE_AUTHOR("Maud Spierings <maudspierings@gocontroll.com>");
+MODULE_LICENSE("GPL");

-- 
2.51.0

[PATCH v4 3/4] arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

Add the missing backlight driver.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso | 32 ++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
index e3965caca6be4..e8107145a7f3b 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av101hdt-a10.dtso
@@ -17,6 +17,7 @@
 
 	panel {
 		compatible = "boe,av101hdt-a10";
+		backlight = <&backlight>;
 		enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
 		pinctrl-0 = <&pinctrl_panel>;
 		pinctrl-names = "default";
@@ -40,7 +41,38 @@ reg_vbus: regulator-vbus {
 	};
 };
 
+&i2c4 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		led@0 {
+			reg = <0>;
+			led-sources = <0 1 2>;
+			default-brightness = <50>;
+		};
+	};
+};
+
 &iomuxc {
+	pinctrl_backlight: backlightgrp {
+		fsl,pins = <
+			MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+				(MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+		>;
+	};
+
 	pinctrl_panel: panelgrp {
 		fsl,pins = <
 			MX8MP_IOMUXC_GPIO1_IO07__GPIO1_IO07

-- 
2.51.0

[PATCH v4 4/4] arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight

[Maud Spierings via B4 Relay]

From: Maud Spierings <maudspierings@gocontroll.com>

Add the missing backlight.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso | 27 +++++++++++++++++++++-
 1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
index 3eb665ce9d5d2..c320e0f563af9 100644
--- a/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
+++ b/arch/arm64/boot/dts/freescale/imx8mp-tx8p-ml81-moduline-display-106-av123z7m-n17.dtso
@@ -16,6 +16,7 @@
 
 	panel {
 		compatible = "boe,av123z7m-n17";
+		backlight = <&backlight>;
 		enable-gpios = <&gpio1 7 GPIO_ACTIVE_HIGH>;
 		pinctrl-0 = <&pinctrl_panel>;
 		pinctrl-names = "default";
@@ -91,10 +92,34 @@ lvds1_out: endpoint {
 		};
 	};
 
-	/* max25014 @ 0x6f */
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		led@0 {
+			reg = <0>;
+			led-sources = <0 1 2 3>;
+			default-brightness = <50>;
+		};
+	};
 };
 
 &iomuxc {
+	pinctrl_backlight: backlightgrp {
+		fsl,pins = <
+			MX8MP_IOMUXC_GPIO1_IO04__GPIO1_IO04
+				(MX8MP_PULL_UP | MX8MP_PULL_ENABLE)
+		>;
+	};
+
 	pinctrl_lvds_bridge: lvdsbridgegrp {
 		fsl,pins = <
 			MX8MP_IOMUXC_SAI1_TXD2__GPIO4_IO14

-- 
2.51.0

Re: [PATCH v4 1/4] dt-bindings: backlight: Add max25014 bindings

[Frank Li]

On Thu, Oct 09, 2025 at 08:48:25AM +0200, Maud Spierings via B4 Relay wrote:
> From: Maud Spierings <maudspierings@gocontroll.com>

Subject needn't double bindings.

dt-bindings: backlight: Add max25014 support

>
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
>
> In the current implementation the control registers for channel 1,
> control all channels. So only one led subnode with led-sources is
> supported right now. If at some point the driver functionality is
> expanded the bindings can be easily extended with it.

Need descript hardware, not driver. Need descript full functions even though
driver have not implement yet.

>
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> ---
>  .../bindings/leds/backlight/maxim,max25014.yaml    | 109 +++++++++++++++++++++
>  MAINTAINERS                                        |   5 +
>  2 files changed, 114 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> new file mode 100644
> index 0000000000000..496520e1374e5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,109 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Maxim max25014 backlight controller
> +
> +maintainers:
> +  - Maud Spierings <maudspierings@gocontroll.com>
> +
> +properties:
> +  compatible:
> +    enum:
> +      - maxim,max25014
> +
> +  reg:
> +    maxItems: 1
> +
> +  "#address-cells":
> +    const: 1
> +
> +  "#size-cells":
> +    const: 0
> +
> +  enable-gpios:
> +    maxItems: 1
> +
> +  interrupts:
> +    maxItems: 1
> +
> +  power-supply:
> +    description: Regulator which controls the boost converter input rail.
> +
> +  pwms:
> +    maxItems: 1
> +
> +  maxim,iset:
> +    $ref: /schemas/types.yaml#/definitions/uint32
> +    maximum: 15
> +    default: 11
> +    description:
> +      Value of the ISET register field. This controls the current scale of the
> +      outputs, a higher number means more current.

Can't use register value directly, need use standard unit. or percentage

100: means max, 0: min.

> +
> +patternProperties:
> +  "^led@[01]$":
> +    type: object
> +    description: Properties for a string of connected LEDs.
> +    $ref: common.yaml#
> +
> +    properties:
> +      reg:
> +        const: 0
> +
> +      led-sources:
> +        allOf:
> +          - minItems: 1
> +            maxItems: 4
> +            items:
> +              minimum: 0
> +              maximum: 3
> +            default: [0, 1, 2, 3]
> +
> +      default-brightness:
> +        minimum: 0
> +        maximum: 100
> +        default: 50
> +
> +    required:
> +      - reg
> +
> +    additionalProperties: false

there are $ref, should use unevaluatedProperties: false

Frank
> +
> +required:
> +  - compatible
> +  - reg
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +    #include <dt-bindings/interrupt-controller/irq.h>
> +
> +    i2c {
> +        #address-cells = <1>;
> +        #size-cells = <0>;
> +
> +        backlight@6f {
> +            compatible = "maxim,max25014";
> +            reg = <0x6f>;
> +            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> +            interrupt-parent = <&gpio1>;
> +            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> +            power-supply = <&reg_backlight>;
> +            pwms = <&pwm1>;
> +            maxim,iset = <7>;
> +
> +            #address-cells = <1>;
> +            #size-cells = <0>;
> +
> +            led@0 {
> +                reg = <0>;
> +                led-sources = <0 1 2 3>;
> +                default-brightness = <50>;
> +            };
> +        };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 47fbc5e06808f..be5e2515900ce 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15171,6 +15171,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
>  F:	drivers/media/i2c/max2175*
>  F:	include/uapi/linux/max2175.h
>
> +MAX25014 BACKLIGHT DRIVER
> +M:	Maud Spierings <maudspierings@gocontroll.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> +
>  MAX31335 RTC DRIVER
>  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
>  L:	linux-rtc@vger.kernel.org
>
> --
> 2.51.0
>
>

Re: [PATCH v4 1/4] dt-bindings: backlight: Add max25014 bindings

[Conor Dooley]

[-- Attachment #1: Type: text/plain, Size: 6354 bytes --]

On Thu, Oct 09, 2025 at 10:55:42AM -0400, Frank Li wrote:
> On Thu, Oct 09, 2025 at 08:48:25AM +0200, Maud Spierings via B4 Relay wrote:
> > From: Maud Spierings <maudspierings@gocontroll.com>
> 
> Subject needn't double bindings.
> 
> dt-bindings: backlight: Add max25014 support
> 
> >
> > The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> > with integrated boost controller.
> >
> > In the current implementation the control registers for channel 1,
> > control all channels. So only one led subnode with led-sources is
> > supported right now. If at some point the driver functionality is
> > expanded the bindings can be easily extended with it.
> 
> Need descript hardware, not driver. Need descript full functions even though
> driver have not implement yet.
> 
> >
> > Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> > ---
> >  .../bindings/leds/backlight/maxim,max25014.yaml    | 109 +++++++++++++++++++++
> >  MAINTAINERS                                        |   5 +
> >  2 files changed, 114 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > new file mode 100644
> > index 0000000000000..496520e1374e5
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > @@ -0,0 +1,109 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/leds/backlight/maxim,max25014.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: Maxim max25014 backlight controller
> > +
> > +maintainers:
> > +  - Maud Spierings <maudspierings@gocontroll.com>
> > +
> > +properties:
> > +  compatible:
> > +    enum:
> > +      - maxim,max25014
> > +
> > +  reg:
> > +    maxItems: 1
> > +
> > +  "#address-cells":
> > +    const: 1
> > +
> > +  "#size-cells":
> > +    const: 0
> > +
> > +  enable-gpios:
> > +    maxItems: 1
> > +
> > +  interrupts:
> > +    maxItems: 1
> > +
> > +  power-supply:
> > +    description: Regulator which controls the boost converter input rail.
> > +
> > +  pwms:
> > +    maxItems: 1
> > +
> > +  maxim,iset:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    maximum: 15
> > +    default: 11
> > +    description:
> > +      Value of the ISET register field. This controls the current scale of the
> > +      outputs, a higher number means more current.
> 
> Can't use register value directly, need use standard unit. or percentage
> 
> 100: means max, 0: min.

From that datasheet, it seems like the values here don't neatly map to
currents, because it depends on the value of the iref register. I don't
love percentages here either, too much of a force-fit for me.

If current is used, a property for the reference resistor will be
needed, to compute the register values. That only makes sense to me if
Maxim/Analog provide a formula that can be used to calculate the
appropriate register value, and I did not find one in the datasheet from
my quick skim, only two example current tables.
Sure, those two examples can be reverse-engineered to give a way to
compute it, but can we be sure that the numbers apply across the whole
range of permitted values for the resistor?

I don't like using register values for stuff, but I think it is the most
accurate and least likely to cause problems way of representing this.

Maud, on the language used - its the ISET field in the ISET register, I
think the property should make that clear.

> > +patternProperties:
> > +  "^led@[01]$":

Why does this have [01] if reg has to be zero?

> > +    type: object
> > +    description: Properties for a string of connected LEDs.
> > +    $ref: common.yaml#
> > +
> > +    properties:
> > +      reg:
> > +        const: 0
> > +
> > +      led-sources:
> > +        allOf:
> > +          - minItems: 1
> > +            maxItems: 4
> > +            items:
> > +              minimum: 0
> > +              maximum: 3
> > +            default: [0, 1, 2, 3]
> > +
> > +      default-brightness:
> > +        minimum: 0
> > +        maximum: 100
> > +        default: 50
> > +
> > +    required:
> > +      - reg
> > +
> > +    additionalProperties: false
> 
> there are $ref, should use unevaluatedProperties: false

Not always, looks like they've listed some properties from the file,
which would make addtionalPropeties: false correct if they dont want
the other properties in the file to be used.

> 
> Frank
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    #include <dt-bindings/gpio/gpio.h>
> > +    #include <dt-bindings/interrupt-controller/irq.h>
> > +
> > +    i2c {
> > +        #address-cells = <1>;
> > +        #size-cells = <0>;
> > +
> > +        backlight@6f {
> > +            compatible = "maxim,max25014";
> > +            reg = <0x6f>;
> > +            enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
> > +            interrupt-parent = <&gpio1>;
> > +            interrupts = <2 IRQ_TYPE_EDGE_FALLING>;
> > +            power-supply = <&reg_backlight>;
> > +            pwms = <&pwm1>;
> > +            maxim,iset = <7>;
> > +
> > +            #address-cells = <1>;
> > +            #size-cells = <0>;
> > +
> > +            led@0 {
> > +                reg = <0>;
> > +                led-sources = <0 1 2 3>;
> > +                default-brightness = <50>;
> > +            };
> > +        };
> > +    };
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 47fbc5e06808f..be5e2515900ce 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -15171,6 +15171,11 @@ F:	Documentation/userspace-api/media/drivers/max2175.rst
> >  F:	drivers/media/i2c/max2175*
> >  F:	include/uapi/linux/max2175.h
> >
> > +MAX25014 BACKLIGHT DRIVER
> > +M:	Maud Spierings <maudspierings@gocontroll.com>
> > +S:	Maintained
> > +F:	Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> > +
> >  MAX31335 RTC DRIVER
> >  M:	Antoniu Miclaus <antoniu.miclaus@analog.com>
> >  L:	linux-rtc@vger.kernel.org
> >
> > --
> > 2.51.0
> >
> >

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