[PATCH v7 0/4] backlight: add new max25014 backlight driver

[PATCH v7 0/4] backlight: add new max25014 backlight driver

[Maud Spierings]

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 v7:
- remove the led subnodes
- always enable the regulator by using devm_regulator_get_enable()
- remove the no longer required gotos and simplify early returns
- fix the name of the SHORTED_LED error field
- fix the name of the SHORTGND error field
- use the proper backlight helper functions for setting/getting
  brightness
- Link to v6: https://lore.kernel.org/r/20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com

Changes in v6:
- fixup changes in v4 where default brightness handling was changed but
  not noted
- remove leftover comment about initializing brightness
- use BIT definitions for fields in the DIAG register
- apply reverse christmas tree initialization of local variables
- remove !=0 from checks, just check if (ret)
- remove > 0 from checks, just check if (val)
- use dev_err_probe() more
- set enable gpio high in the get() instead of seperately calling set()
- change usleep_range() to fsleep()
- remove null checks when setting gpio value
- get regular regulator, not optional to avoid further NULL checks in
  case none is provided
- introduce max25014_initial_power_state() to check if the bootloader
  has already initialized the backlight and to correctly set props.power
- squash max25014_register_control() into max25014_update_status()
- in max25014_configure() perform extra checking on the DISABLE register
  now that the state from the bootloader is taken into account
- Link to v5: https://lore.kernel.org/r/20251107-max25014-v5-0-9a6aa57306bf@gocontroll.com

Changes in v5:
- moved comment about current functions of the driver to the actual
  comment section of the commit
- fixed the led@0 property, regex patternProperty is not needed as of
  now
- added extra clarification about the ISET field/register
- moved #address-cells and #size-cells to the correct location
- remove leftover default-brightness in backlight nodes
- Link to v4: https://lore.kernel.org/r/20251009-max25014-v4-0-6adb2a0aa35f@gocontroll.com

Changes in v4:
- remove setting default brightness, let backlight core take care of it
- 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 support
      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    |  91 +++++
 MAINTAINERS                                        |   6 +
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso |  26 ++
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso |  21 +-
 drivers/video/backlight/Kconfig                    |   7 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/max25014.c                 | 377 +++++++++++++++++++++
 7 files changed, 528 insertions(+), 1 deletion(-)
---
base-commit: a0c666c25aeefd16f4b088c6549a6fb6b65a8a1d
change-id: 20250626-max25014-4207591e1af5

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

[PATCH v7 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 v7:
- remove the led subnodes
- always enable the regulator by using devm_regulator_get_enable()
- remove the no longer required gotos and simplify early returns
- fix the name of the SHORTED_LED error field
- fix the name of the SHORTGND error field
- use the proper backlight helper functions for setting/getting
  brightness
- Link to v6: https://lore.kernel.org/r/20251201-max25014-v6-0-88e3ac8112ff@gocontroll.com

Changes in v6:
- fixup changes in v4 where default brightness handling was changed but
  not noted
- remove leftover comment about initializing brightness
- use BIT definitions for fields in the DIAG register
- apply reverse christmas tree initialization of local variables
- remove !=0 from checks, just check if (ret)
- remove > 0 from checks, just check if (val)
- use dev_err_probe() more
- set enable gpio high in the get() instead of seperately calling set()
- change usleep_range() to fsleep()
- remove null checks when setting gpio value
- get regular regulator, not optional to avoid further NULL checks in
  case none is provided
- introduce max25014_initial_power_state() to check if the bootloader
  has already initialized the backlight and to correctly set props.power
- squash max25014_register_control() into max25014_update_status()
- in max25014_configure() perform extra checking on the DISABLE register
  now that the state from the bootloader is taken into account
- Link to v5: https://lore.kernel.org/r/20251107-max25014-v5-0-9a6aa57306bf@gocontroll.com

Changes in v5:
- moved comment about current functions of the driver to the actual
  comment section of the commit
- fixed the led@0 property, regex patternProperty is not needed as of
  now
- added extra clarification about the ISET field/register
- moved #address-cells and #size-cells to the correct location
- remove leftover default-brightness in backlight nodes
- Link to v4: https://lore.kernel.org/r/20251009-max25014-v4-0-6adb2a0aa35f@gocontroll.com

Changes in v4:
- remove setting default brightness, let backlight core take care of it
- 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 support
      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    |  91 +++++
 MAINTAINERS                                        |   6 +
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso |  26 ++
 ...x8p-ml81-moduline-display-106-av123z7m-n17.dtso |  21 +-
 drivers/video/backlight/Kconfig                    |   7 +
 drivers/video/backlight/Makefile                   |   1 +
 drivers/video/backlight/max25014.c                 | 377 +++++++++++++++++++++
 7 files changed, 528 insertions(+), 1 deletion(-)
---
base-commit: a0c666c25aeefd16f4b088c6549a6fb6b65a8a1d
change-id: 20250626-max25014-4207591e1af5

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

[PATCH v7 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

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

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>

---

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.
---
 .../bindings/leds/backlight/maxim,max25014.yaml    | 91 ++++++++++++++++++++++
 MAINTAINERS                                        |  5 ++
 2 files changed, 96 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 000000000000..c499e6224a8f
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
@@ -0,0 +1,91 @@
+# 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
+
+  default-brightness:
+    minimum: 0
+    maximum: 100
+    default: 50
+
+  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 field in the ISET register. This controls the current
+      scale of the outputs, a higher number means more current.
+
+  maxim,strings:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description:
+      A 4-bit bitfield that describes which led strings to turn on.
+    minItems: 4
+    maxItems: 4
+    items:
+      maximum: 1
+    default:
+      [1 1 1 1]
+
+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>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            default-brightness = <50>;
+            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>;
+            maxim,strings = <1 1 1 0>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 9b1b87d08fac..eb248f4634ac 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15515,6 +15515,11 @@ 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

-- 
2.52.0

[PATCH v7 1/4] dt-bindings: backlight: Add max25014 support

[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>

---

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.
---
 .../bindings/leds/backlight/maxim,max25014.yaml    | 91 ++++++++++++++++++++++
 MAINTAINERS                                        |  5 ++
 2 files changed, 96 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 000000000000..c499e6224a8f
--- /dev/null
+++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
@@ -0,0 +1,91 @@
+# 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
+
+  default-brightness:
+    minimum: 0
+    maximum: 100
+    default: 50
+
+  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 field in the ISET register. This controls the current
+      scale of the outputs, a higher number means more current.
+
+  maxim,strings:
+    $ref: /schemas/types.yaml#/definitions/uint32-array
+    description:
+      A 4-bit bitfield that describes which led strings to turn on.
+    minItems: 4
+    maxItems: 4
+    items:
+      maximum: 1
+    default:
+      [1 1 1 1]
+
+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>;
+            #address-cells = <1>;
+            #size-cells = <0>;
+            default-brightness = <50>;
+            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>;
+            maxim,strings = <1 1 1 0>;
+        };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 9b1b87d08fac..eb248f4634ac 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15515,6 +15515,11 @@ 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

-- 
2.52.0

[PATCH v7 2/4] backlight: add max25014atg backlight

[Maud Spierings]

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 | 377 +++++++++++++++++++++++++++++++++++++
 4 files changed, 386 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index eb248f4634ac..346a8ede3f71 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15519,6 +15519,7 @@ 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 a7a3fbaf7c29..6cd3a1673511 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -282,6 +282,13 @@ 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 794820a98ed4..21c8313cfb12 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -47,6 +47,7 @@ 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 000000000000..3ee45617261f
--- /dev/null
+++ b/drivers/video/backlight/max25014.c
@@ -0,0 +1,377 @@
+// 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_SHORTGND         0x1C
+#define MAX25014_SHORTED_LED      0x1D
+#define MAX25014_MASK             0x1E
+#define MAX25014_DIAG             0x1F
+
+#define MAX25014_ISET_ENA         BIT(5)
+#define MAX25014_ISET_PSEN        BIT(4)
+#define MAX25014_IMODE_HDIM       BIT(2)
+#define MAX25014_SETTING_FPWM     GENMASK(6, 4)
+#define MAX25014_DISABLE_DIS_MASK GENMASK(3, 0)
+#define MAX25014_DIAG_OT          BIT(0)
+#define MAX25014_DIAG_OTW         BIT(1)
+#define MAX25014_DIAG_HW_RST      BIT(2)
+#define MAX25014_DIAG_BSTOV       BIT(3)
+#define MAX25014_DIAG_BSTUV       BIT(4)
+#define MAX25014_DIAG_IREFOOR     BIT(5)
+
+struct max25014 {
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct regmap *regmap;
+	struct gpio_desc *enable;
+	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,
+};
+
+static int max25014_initial_power_state(struct max25014 *maxim)
+{
+	uint32_t val;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_ISET, &val);
+	if (ret)
+		return ret;
+
+	return val & MAX25014_ISET_ENA ? BACKLIGHT_POWER_ON : BACKLIGHT_POWER_OFF;
+}
+
+static int max25014_check_errors(struct max25014 *maxim)
+{
+	uint32_t val;
+	uint8_t i;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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_SHORTGND, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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_SHORTED_LED, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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)
+		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 && val != MAX25014_DIAG_HW_RST) {
+		if (val & MAX25014_DIAG_OT)
+			dev_err(&maxim->client->dev,
+				"Overtemperature shutdown\n");
+		if (val & MAX25014_DIAG_OTW)
+			dev_err(&maxim->client->dev,
+				 "Chip is getting too hot (>125C)\n");
+		if (val & MAX25014_DIAG_BSTOV)
+			dev_err(&maxim->client->dev,
+				"Boost converter overvoltage\n");
+		if (val & MAX25014_DIAG_BSTUV)
+			dev_err(&maxim->client->dev,
+				"Boost converter undervoltage\n");
+		if (val & MAX25014_DIAG_IREFOOR)
+			dev_err(&maxim->client->dev, "IREF out of range\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * 1. disable unused strings
+ * 2. set dim mode
+ * 3. set setting register
+ * 4. enable the backlight
+ */
+static int max25014_configure(struct max25014 *maxim, int initial_state)
+{
+	uint32_t val;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
+	if (ret)
+		return ret;
+
+	/*
+	 * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
+	 * it needs to be changed at all to prevent the backlight flashing when
+	 * it is configured correctly by the bootloader
+	 */
+	if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
+		if (initial_state == BACKLIGHT_POWER_ON) {
+			ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
+			if (ret)
+				return ret;
+		}
+		ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
+			   val & ~MAX25014_SETTING_FPWM);
+	if (ret)
+		return ret;
+
+	return regmap_write(maxim->regmap, MAX25014_ISET,
+			   maxim->iset | MAX25014_ISET_ENA |
+			   MAX25014_ISET_PSEN);
+}
+
+static int max25014_update_status(struct backlight_device *bl_dev)
+{
+	struct max25014 *maxim = bl_get_data(bl_dev);
+	uint32_t reg;
+	int ret;
+
+	reg  = TON_STEP * backlight_get_brightness(bl_dev);
+
+	/*
+	 * 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(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
+	if (ret != 0)
+		return ret;
+	ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
+	if (ret != 0)
+		return ret;
+	return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
+}
+
+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;
+	uint32_t strings[4];
+	int res, i;
+
+	res = of_property_count_u32_elems(node, "maxim,strings");
+	if (res == 4) {
+		of_property_read_u32_array(node, "maxim,strings", strings, 4);
+		for (i = 0; i < 4; i++) {
+			if (strings[i] == 0)
+				maxim->strings_mask |= 1 << i;
+	}
+	} else {
+		maxim->strings_mask = 0;
+	}
+
+	*initial_brightness = 50U;
+	of_property_read_u32(node, "default-brightness", initial_brightness);
+
+	maxim->iset = MAX25014_ISET_DEFAULT_100;
+	of_property_read_u32(node, "maxim,iset", &maxim->iset);
+
+	if (maxim->iset > 15)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid iset, should be a value from 0-15, entered was %d\n",
+				     maxim->iset);
+
+	if (*initial_brightness > 100)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
+				     *initial_brightness);
+
+	return 0;
+}
+
+static int max25014_probe(struct i2c_client *cl)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
+	struct backlight_properties props;
+	uint32_t initial_brightness = 50;
+	struct backlight_device *bl;
+	struct max25014 *maxim;
+	int ret;
+
+	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)
+		return ret;
+
+	ret = devm_regulator_get_enable(&maxim->client->dev, "power");
+	if (ret)
+		return dev_err_probe(&maxim->client->dev, ret,
+				     "failed to get power-supply");
+
+	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
+						GPIOD_OUT_HIGH);
+	if (IS_ERR(maxim->enable))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
+				    "failed to get enable gpio\n");
+
+	/* Datasheet Electrical Characteristics tSTARTUP 2ms */
+	fsleep(2000);
+
+	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
+	if (IS_ERR(maxim->regmap))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
+			"failed to initialize the i2c regmap\n");
+
+	i2c_set_clientdata(cl, maxim);
+
+	ret = max25014_check_errors(maxim);
+	if (ret) /* error is already reported in the above function */
+		return ret;
+
+	ret = max25014_initial_power_state(maxim);
+	if (ret < 0)
+		return dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+	props.brightness = initial_brightness;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+	props.power = ret;
+
+	ret = max25014_configure(maxim, ret);
+	if (ret)
+		return dev_err_probe(&maxim->client->dev, ret, "device config error");
+
+	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
+					    &maxim->client->dev, maxim,
+					    &max25014_bl_ops, &props);
+	if (IS_ERR(bl))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
+				    "failed to register backlight\n");
+
+	maxim->bl = bl;
+
+	backlight_update_status(maxim->bl);
+
+	return 0;
+}
+
+static void max25014_remove(struct i2c_client *cl)
+{
+	struct max25014 *maxim = i2c_get_clientdata(cl);
+
+	backlight_device_set_brightness(maxim->bl, 0);
+	gpiod_set_value_cansleep(maxim->enable, 0);
+}
+
+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");

-- 
2.52.0

[PATCH v7 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 | 377 +++++++++++++++++++++++++++++++++++++
 4 files changed, 386 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index eb248f4634ac..346a8ede3f71 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -15519,6 +15519,7 @@ 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 a7a3fbaf7c29..6cd3a1673511 100644
--- a/drivers/video/backlight/Kconfig
+++ b/drivers/video/backlight/Kconfig
@@ -282,6 +282,13 @@ 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 794820a98ed4..21c8313cfb12 100644
--- a/drivers/video/backlight/Makefile
+++ b/drivers/video/backlight/Makefile
@@ -47,6 +47,7 @@ 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 000000000000..3ee45617261f
--- /dev/null
+++ b/drivers/video/backlight/max25014.c
@@ -0,0 +1,377 @@
+// 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_SHORTGND         0x1C
+#define MAX25014_SHORTED_LED      0x1D
+#define MAX25014_MASK             0x1E
+#define MAX25014_DIAG             0x1F
+
+#define MAX25014_ISET_ENA         BIT(5)
+#define MAX25014_ISET_PSEN        BIT(4)
+#define MAX25014_IMODE_HDIM       BIT(2)
+#define MAX25014_SETTING_FPWM     GENMASK(6, 4)
+#define MAX25014_DISABLE_DIS_MASK GENMASK(3, 0)
+#define MAX25014_DIAG_OT          BIT(0)
+#define MAX25014_DIAG_OTW         BIT(1)
+#define MAX25014_DIAG_HW_RST      BIT(2)
+#define MAX25014_DIAG_BSTOV       BIT(3)
+#define MAX25014_DIAG_BSTUV       BIT(4)
+#define MAX25014_DIAG_IREFOOR     BIT(5)
+
+struct max25014 {
+	struct i2c_client *client;
+	struct backlight_device *bl;
+	struct regmap *regmap;
+	struct gpio_desc *enable;
+	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,
+};
+
+static int max25014_initial_power_state(struct max25014 *maxim)
+{
+	uint32_t val;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_ISET, &val);
+	if (ret)
+		return ret;
+
+	return val & MAX25014_ISET_ENA ? BACKLIGHT_POWER_ON : BACKLIGHT_POWER_OFF;
+}
+
+static int max25014_check_errors(struct max25014 *maxim)
+{
+	uint32_t val;
+	uint8_t i;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_OPEN, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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_SHORTGND, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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_SHORTED_LED, &val);
+	if (ret)
+		return ret;
+	if (val) {
+		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)
+		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 && val != MAX25014_DIAG_HW_RST) {
+		if (val & MAX25014_DIAG_OT)
+			dev_err(&maxim->client->dev,
+				"Overtemperature shutdown\n");
+		if (val & MAX25014_DIAG_OTW)
+			dev_err(&maxim->client->dev,
+				 "Chip is getting too hot (>125C)\n");
+		if (val & MAX25014_DIAG_BSTOV)
+			dev_err(&maxim->client->dev,
+				"Boost converter overvoltage\n");
+		if (val & MAX25014_DIAG_BSTUV)
+			dev_err(&maxim->client->dev,
+				"Boost converter undervoltage\n");
+		if (val & MAX25014_DIAG_IREFOOR)
+			dev_err(&maxim->client->dev, "IREF out of range\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ * 1. disable unused strings
+ * 2. set dim mode
+ * 3. set setting register
+ * 4. enable the backlight
+ */
+static int max25014_configure(struct max25014 *maxim, int initial_state)
+{
+	uint32_t val;
+	int ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_DISABLE, &val);
+	if (ret)
+		return ret;
+
+	/*
+	 * Strings can only be disabled when MAX25014_ISET_ENA == 0, check if
+	 * it needs to be changed at all to prevent the backlight flashing when
+	 * it is configured correctly by the bootloader
+	 */
+	if (!((val & MAX25014_DISABLE_DIS_MASK) == maxim->strings_mask)) {
+		if (initial_state == BACKLIGHT_POWER_ON) {
+			ret = regmap_write(maxim->regmap, MAX25014_ISET, 0);
+			if (ret)
+				return ret;
+		}
+		ret = regmap_write(maxim->regmap, MAX25014_DISABLE, maxim->strings_mask);
+		if (ret)
+			return ret;
+	}
+
+	ret = regmap_write(maxim->regmap, MAX25014_IMODE, MAX25014_IMODE_HDIM);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(maxim->regmap, MAX25014_SETTING, &val);
+	if (ret)
+		return ret;
+
+	ret = regmap_write(maxim->regmap, MAX25014_SETTING,
+			   val & ~MAX25014_SETTING_FPWM);
+	if (ret)
+		return ret;
+
+	return regmap_write(maxim->regmap, MAX25014_ISET,
+			   maxim->iset | MAX25014_ISET_ENA |
+			   MAX25014_ISET_PSEN);
+}
+
+static int max25014_update_status(struct backlight_device *bl_dev)
+{
+	struct max25014 *maxim = bl_get_data(bl_dev);
+	uint32_t reg;
+	int ret;
+
+	reg  = TON_STEP * backlight_get_brightness(bl_dev);
+
+	/*
+	 * 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(maxim->regmap, MAX25014_TON_1_4_LSB, reg & 0b00000011);
+	if (ret != 0)
+		return ret;
+	ret = regmap_write(maxim->regmap, MAX25014_TON1L, (reg >> 2) & 0b11111111);
+	if (ret != 0)
+		return ret;
+	return regmap_write(maxim->regmap, MAX25014_TON1H, (reg >> 10) & 0b11111111);
+}
+
+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;
+	uint32_t strings[4];
+	int res, i;
+
+	res = of_property_count_u32_elems(node, "maxim,strings");
+	if (res == 4) {
+		of_property_read_u32_array(node, "maxim,strings", strings, 4);
+		for (i = 0; i < 4; i++) {
+			if (strings[i] == 0)
+				maxim->strings_mask |= 1 << i;
+	}
+	} else {
+		maxim->strings_mask = 0;
+	}
+
+	*initial_brightness = 50U;
+	of_property_read_u32(node, "default-brightness", initial_brightness);
+
+	maxim->iset = MAX25014_ISET_DEFAULT_100;
+	of_property_read_u32(node, "maxim,iset", &maxim->iset);
+
+	if (maxim->iset > 15)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid iset, should be a value from 0-15, entered was %d\n",
+				     maxim->iset);
+
+	if (*initial_brightness > 100)
+		return dev_err_probe(dev, -EINVAL,
+				     "Invalid initial brightness, should be a value from 0-100, entered was %d\n",
+				     *initial_brightness);
+
+	return 0;
+}
+
+static int max25014_probe(struct i2c_client *cl)
+{
+	const struct i2c_device_id *id = i2c_client_get_device_id(cl);
+	struct backlight_properties props;
+	uint32_t initial_brightness = 50;
+	struct backlight_device *bl;
+	struct max25014 *maxim;
+	int ret;
+
+	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)
+		return ret;
+
+	ret = devm_regulator_get_enable(&maxim->client->dev, "power");
+	if (ret)
+		return dev_err_probe(&maxim->client->dev, ret,
+				     "failed to get power-supply");
+
+	maxim->enable = devm_gpiod_get_optional(&maxim->client->dev, "enable",
+						GPIOD_OUT_HIGH);
+	if (IS_ERR(maxim->enable))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->enable),
+				    "failed to get enable gpio\n");
+
+	/* Datasheet Electrical Characteristics tSTARTUP 2ms */
+	fsleep(2000);
+
+	maxim->regmap = devm_regmap_init_i2c(cl, &max25014_regmap_config);
+	if (IS_ERR(maxim->regmap))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(maxim->regmap),
+			"failed to initialize the i2c regmap\n");
+
+	i2c_set_clientdata(cl, maxim);
+
+	ret = max25014_check_errors(maxim);
+	if (ret) /* error is already reported in the above function */
+		return ret;
+
+	ret = max25014_initial_power_state(maxim);
+	if (ret < 0)
+		return dev_err_probe(&maxim->client->dev, ret, "Could not get enabled state\n");
+
+	memset(&props, 0, sizeof(struct backlight_properties));
+	props.type = BACKLIGHT_PLATFORM;
+	props.max_brightness = MAX_BRIGHTNESS;
+	props.brightness = initial_brightness;
+	props.scale = BACKLIGHT_SCALE_LINEAR;
+	props.power = ret;
+
+	ret = max25014_configure(maxim, ret);
+	if (ret)
+		return dev_err_probe(&maxim->client->dev, ret, "device config error");
+
+	bl = devm_backlight_device_register(&maxim->client->dev, id->name,
+					    &maxim->client->dev, maxim,
+					    &max25014_bl_ops, &props);
+	if (IS_ERR(bl))
+		return dev_err_probe(&maxim->client->dev, PTR_ERR(bl),
+				    "failed to register backlight\n");
+
+	maxim->bl = bl;
+
+	backlight_update_status(maxim->bl);
+
+	return 0;
+}
+
+static void max25014_remove(struct i2c_client *cl)
+{
+	struct max25014 *maxim = i2c_get_clientdata(cl);
+
+	backlight_device_set_brightness(maxim->bl, 0);
+	gpiod_set_value_cansleep(maxim->enable, 0);
+}
+
+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");

-- 
2.52.0

[PATCH v7 3/4] arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight

[Maud Spierings]

Add the missing backlight driver.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...x8p-ml81-moduline-display-106-av101hdt-a10.dtso | 26 ++++++++++++++++++++++
 1 file changed, 26 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 e3965caca6be..e121c58b730b 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 +41,32 @@ reg_vbus: regulator-vbus {
 	};
 };
 
+&i2c4 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+		maxim,strings = <1 1 1 0>;
+	};
+};
+
 &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

-- 
2.52.0

[PATCH v7 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 | 26 ++++++++++++++++++++++
 1 file changed, 26 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 e3965caca6be..e121c58b730b 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 +41,32 @@ reg_vbus: regulator-vbus {
 	};
 };
 
+&i2c4 {
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+		maxim,strings = <1 1 1 0>;
+	};
+};
+
 &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

-- 
2.52.0

[PATCH v7 4/4] arm64: dts: freescale: moduline-display-av123z7m-n17: add backlight

[Maud Spierings]

Add the missing backlight.

Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
---
 ...tx8p-ml81-moduline-display-106-av123z7m-n17.dtso | 21 ++++++++++++++++++++-
 1 file changed, 20 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 3eb665ce9d5d..66d98a18d898 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 +92,28 @@ lvds1_out: endpoint {
 		};
 	};
 
-	/* max25014 @ 0x6f */
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+		maxim,strings = <1 1 1 1>;
+	};
 };
 
 &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

-- 
2.52.0

[PATCH v7 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>
---
 ...tx8p-ml81-moduline-display-106-av123z7m-n17.dtso | 21 ++++++++++++++++++++-
 1 file changed, 20 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 3eb665ce9d5d..66d98a18d898 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 +92,28 @@ lvds1_out: endpoint {
 		};
 	};
 
-	/* max25014 @ 0x6f */
+	backlight: backlight@6f {
+		compatible = "maxim,max25014";
+		reg = <0x6f>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		default-brightness = <50>;
+		enable-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pinctrl_backlight>;
+		maxim,iset = <7>;
+		maxim,strings = <1 1 1 1>;
+	};
 };
 
 &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

-- 
2.52.0

Re: [PATCH v7 2/4] backlight: add max25014atg backlight

[kernel test robot]

:::::: 
:::::: Manual check reason: "low confidence static check warning: drivers/video/backlight/max25014.c:375:1: sparse: sparse: bad integer constant expression"
:::::: 

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
In-Reply-To: <20260123-max25014-v7-2-15e504b9acc7@gocontroll.com>
References: <20260123-max25014-v7-2-15e504b9acc7@gocontroll.com>
TO: Maud Spierings via B4 Relay <devnull+maudspierings.gocontroll.com@kernel.org>
TO: Lee Jones <lee@kernel.org>
TO: Daniel Thompson <danielt@kernel.org>
TO: Jingoo Han <jingoohan1@gmail.com>
TO: Pavel Machek <pavel@kernel.org>
TO: Rob Herring <robh@kernel.org>
TO: Krzysztof Kozlowski <krzk@kernel.org>
TO: Conor Dooley <conor+dt@kernel.org>
TO: Helge Deller <deller@gmx.de>
TO: Shawn Guo <shawnguo@kernel.org>
TO: Sascha Hauer <s.hauer@pengutronix.de>
TO: Pengutronix Kernel Team <kernel@pengutronix.de>
TO: Fabio Estevam <festevam@gmail.com>
TO: Liam Girdwood <lgirdwood@gmail.com>
TO: Mark Brown <broonie@kernel.org>
CC: dri-devel@lists.freedesktop.org
CC: linux-leds@vger.kernel.org
CC: devicetree@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-fbdev@vger.kernel.org
CC: imx@lists.linux.dev
CC: linux-arm-kernel@lists.infradead.org
CC: Maud Spierings <maudspierings@gocontroll.com>

Hi Maud,

kernel test robot noticed the following build warnings:

[auto build test WARNING on a0c666c25aeefd16f4b088c6549a6fb6b65a8a1d]

url:    https://github.com/intel-lab-lkp/linux/commits/Maud-Spierings-via-B4-Relay/dt-bindings-backlight-Add-max25014-support/20260123-193429
base:   a0c666c25aeefd16f4b088c6549a6fb6b65a8a1d
patch link:    https://lore.kernel.org/r/20260123-max25014-v7-2-15e504b9acc7%40gocontroll.com
patch subject: [PATCH v7 2/4] backlight: add max25014atg backlight
:::::: branch date: 14 hours ago
:::::: commit date: 14 hours ago
config: nios2-randconfig-r113-20260124 (https://download.01.org/0day-ci/archive/20260124/202601240933.cKsG1DN2-lkp@intel.com/config)
compiler: nios2-linux-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260124/202601240933.cKsG1DN2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/r/202601240933.cKsG1DN2-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> drivers/video/backlight/max25014.c:375:1: sparse: sparse: bad integer constant expression
   drivers/video/backlight/max25014.c:375:1: sparse: sparse: static assertion failed: "MODULE_INFO(description, ...) contains embedded NUL byte"
   drivers/video/backlight/max25014.c:376:1: sparse: sparse: bad integer constant expression
   drivers/video/backlight/max25014.c:376:1: sparse: sparse: static assertion failed: "MODULE_INFO(author, ...) contains embedded NUL byte"
   drivers/video/backlight/max25014.c:377:1: sparse: sparse: bad integer constant expression
   drivers/video/backlight/max25014.c:377:1: sparse: sparse: static assertion failed: "MODULE_INFO(license, ...) contains embedded NUL byte"

vim +375 drivers/video/backlight/max25014.c

7d129add59bae00 Maud Spierings 2026-01-23  374  
7d129add59bae00 Maud Spierings 2026-01-23 @375  MODULE_DESCRIPTION("Maxim MAX25014 backlight driver");

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH v7 1/4] dt-bindings: backlight: Add max25014 support

[Rob Herring]

On Fri, Jan 23, 2026 at 12:31:30PM +0100, Maud Spierings wrote:
> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
> with integrated boost controller.
> 
> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
> 
> ---
> 
> 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.
> ---
>  .../bindings/leds/backlight/maxim,max25014.yaml    | 91 ++++++++++++++++++++++
>  MAINTAINERS                                        |  5 ++
>  2 files changed, 96 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 000000000000..c499e6224a8f
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
> @@ -0,0 +1,91 @@
> +# 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

No child nodes (with addresses), so these should be dropped. And in the 
example.

With that,

Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

Re: [PATCH v7 1/4] dt-bindings: backlight: Add max25014 support

[Maud Spierings]

On 1/29/26 17:04, Rob Herring wrote:
> On Fri, Jan 23, 2026 at 12:31:30PM +0100, Maud Spierings wrote:
>> The Maxim MAX25014 is a 4-channel automotive grade backlight driver IC
>> with integrated boost controller.
>>
>> Signed-off-by: Maud Spierings <maudspierings@gocontroll.com>
>>
>> ---
>>
>> 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.
>> ---
>>   .../bindings/leds/backlight/maxim,max25014.yaml    | 91 ++++++++++++++++++++++
>>   MAINTAINERS                                        |  5 ++
>>   2 files changed, 96 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 000000000000..c499e6224a8f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/leds/backlight/maxim,max25014.yaml
>> @@ -0,0 +1,91 @@
>> +# 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
> 
> No child nodes (with addresses), so these should be dropped. And in the
> example.
> 
> With that,
> 
> Reviewed-by: Rob Herring (Arm) <robh@kernel.org>

And in the actual dtso's too, thanks for spotting this, this passed the 
dts check but indeed is not correct anymore.

kind regards,
Maud

Re: [PATCH v7 2/4] backlight: add max25014atg backlight

[Daniel Thompson]

On Fri, Jan 23, 2026 at 12:31:31PM +0100, Maud Spierings via B4 Relay wrote:
> 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>

Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>


Daniel.