* [PATCH v7 1/4] dt-bindings: backlight: Add max25014 support
2026-01-23 11:31 [PATCH v7 0/4] backlight: add new max25014 backlight driver Maud Spierings via B4 Relay
@ 2026-01-23 11:31 ` Maud Spierings via B4 Relay
2026-01-29 16:04 ` Rob Herring
2026-01-23 11:31 ` [PATCH v7 2/4] backlight: add max25014atg backlight Maud Spierings via B4 Relay
` (2 subsequent siblings)
3 siblings, 1 reply; 8+ messages in thread
From: Maud Spierings via B4 Relay @ 2026-01-23 11:31 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
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 = <®_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
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v7 2/4] backlight: add max25014atg backlight
2026-01-23 11:31 [PATCH v7 0/4] backlight: add new max25014 backlight driver Maud Spierings via B4 Relay
2026-01-23 11:31 ` [PATCH v7 1/4] dt-bindings: backlight: Add max25014 support Maud Spierings via B4 Relay
@ 2026-01-23 11:31 ` Maud Spierings via B4 Relay
2026-03-04 10:38 ` Daniel Thompson
2026-01-23 11:31 ` [PATCH v7 3/4] arm64: dts: freescale: moduline-display-av101hdt-a10: add backlight Maud Spierings via B4 Relay
2026-01-23 11:31 ` [PATCH v7 4/4] arm64: dts: freescale: moduline-display-av123z7m-n17: " Maud Spierings via B4 Relay
3 siblings, 1 reply; 8+ messages in thread
From: Maud Spierings via B4 Relay @ 2026-01-23 11:31 UTC (permalink / raw)
To: Lee Jones, Daniel Thompson, Jingoo Han, Pavel Machek, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Helge Deller, Shawn Guo,
Sascha Hauer, Pengutronix Kernel Team, Fabio Estevam,
Liam Girdwood, Mark Brown
Cc: dri-devel, linux-leds, devicetree, linux-kernel, linux-fbdev, imx,
linux-arm-kernel, Maud Spierings
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
^ permalink raw reply related [flat|nested] 8+ messages in thread