From: Rudraksha Gupta <guptarud@gmail.com>

Add camera flash support for the Samsung Galaxy Express (expressatt).

The flash IC uses a one-wire pulse-count protocol on GPIO 3, powered
by a GPIO-controlled fixed regulator on PMIC MPP 4. The regulator is
modeled as a regulator-fixed node and supplied to the flash IC via
vin-supply.

Downstream references:
Link: https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/drivers/leds/Makefile#L51
Link: https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/arch/arm/mach-msm/board-apexq-camera.c#L591

Reviewed-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
---
 .../dts/qcom/qcom-msm8960-samsung-expressatt.dts   | 43 ++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts b/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
index c4b98af6955d..ad5169a60937 100644
--- a/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
+++ b/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <dt-bindings/input/input.h>
+#include <dt-bindings/leds/common.h>
 #include <dt-bindings/reset/qcom,gcc-msm8960.h>
 
 #include "qcom-msm8960.dtsi"
@@ -61,6 +62,32 @@ touchkey_enable: touchkey-enable {
 		regulator-boot-on;
 	};
 
+	flash_gpio_reg: regulator-flash {
+		compatible = "regulator-fixed";
+		regulator-name = "flash_led_en";
+		regulator-min-microvolt = <3300000>;
+		regulator-max-microvolt = <3300000>;
+		gpio = <&pm8921_mpps 4 GPIO_ACTIVE_HIGH>;
+		enable-active-high;
+		pinctrl-0 = <&flash_led_unlock>;
+		pinctrl-names = "default";
+	};
+
+	camera_flash: led-controller {
+		compatible = "richtek,rt8515";
+		enf-gpios = <&tlmm 3 GPIO_ACTIVE_HIGH>;
+		vin-supply = <&flash_gpio_reg>;
+		richtek,rfs-ohms = <16000>;
+		pinctrl-0 = <&cam_flash_en>;
+		pinctrl-names = "default";
+
+		led {
+			function = LED_FUNCTION_FLASH;
+			color = <LED_COLOR_ID_WHITE>;
+			flash-max-timeout-us = <250000>;
+		};
+	};
+
 	i2c-gpio-touchkey {
 		compatible = "i2c-gpio";
 		#address-cells = <1>;
@@ -247,6 +274,13 @@ touchkey_irq_pin: touchkey-irq-state {
 		drive-strength = <2>;
 		bias-disable;
 	};
+
+	cam_flash_en: cam-flash-en-state {
+		pins = "gpio3";
+		function = "gpio";
+		drive-strength = <16>;
+		bias-pull-down;
+	};
 };
 
 &pm8921 {
@@ -572,3 +606,12 @@ magnetometer@2e {
 		/* TODO: Figure out Mount Matrix */
 	};
 };
+
+&pm8921_mpps {
+	flash_led_unlock: flash-led-unlock-state {
+		pins = "mpp4";
+		function = "digital";
+		output-low;
+		power-source = <PM8921_GPIO_S4>;
+	};
+};

-- 
2.53.0

On 3/18/26 7:34 PM, Rudraksha Gupta via B4 Relay wrote:
> From: Rudraksha Gupta <guptarud@gmail.com>
> 
> Add camera flash support for the Samsung Galaxy Express (expressatt).
> 
> The flash IC uses a one-wire pulse-count protocol on GPIO 3, powered
> by a GPIO-controlled fixed regulator on PMIC MPP 4. The regulator is
> modeled as a regulator-fixed node and supplied to the flash IC via
> vin-supply.
> 
> Downstream references:
> Link: https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/drivers/leds/Makefile#L51
> Link: https://github.com/LineageOS/android_kernel_samsung_d2/blob/stable/cm-12.0-YNG4N/arch/arm/mach-msm/board-apexq-camera.c#L591
> 
> Reviewed-by: David Heidelberg <david@ixit.cz>
> Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
> ---
>  .../dts/qcom/qcom-msm8960-samsung-expressatt.dts   | 43 ++++++++++++++++++++++
>  1 file changed, 43 insertions(+)
> 
> diff --git a/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts b/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
> index c4b98af6955d..ad5169a60937 100644
> --- a/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
> +++ b/arch/arm/boot/dts/qcom/qcom-msm8960-samsung-expressatt.dts
> @@ -1,5 +1,6 @@
>  // SPDX-License-Identifier: GPL-2.0
>  #include <dt-bindings/input/input.h>
> +#include <dt-bindings/leds/common.h>
>  #include <dt-bindings/reset/qcom,gcc-msm8960.h>
>  
>  #include "qcom-msm8960.dtsi"
> @@ -61,6 +62,32 @@ touchkey_enable: touchkey-enable {
>  		regulator-boot-on;
>  	};
>  
> +	flash_gpio_reg: regulator-flash {

"vreg_flash:"

> +		compatible = "regulator-fixed";
> +		regulator-name = "flash_led_en";

"_en" makes it sound like it's an enable pin - if we don't have a better
idea, perhaps VREG_FLASH_3P3?

> +		regulator-min-microvolt = <3300000>;
> +		regulator-max-microvolt = <3300000>;
> +		gpio = <&pm8921_mpps 4 GPIO_ACTIVE_HIGH>;
> +		enable-active-high;
> +		pinctrl-0 = <&flash_led_unlock>;
> +		pinctrl-names = "default";
> +	};
> +
> +	camera_flash: led-controller {

Let's drop the label since it's unused

> +		compatible = "richtek,rt8515";
> +		enf-gpios = <&tlmm 3 GPIO_ACTIVE_HIGH>;
> +		vin-supply = <&flash_gpio_reg>;
> +		richtek,rfs-ohms = <16000>;
> +		pinctrl-0 = <&cam_flash_en>;
> +		pinctrl-names = "default";
> +
> +		led {
> +			function = LED_FUNCTION_FLASH;
> +			color = <LED_COLOR_ID_WHITE>;
> +			flash-max-timeout-us = <250000>;
> +		};
> +	};
> +
>  	i2c-gpio-touchkey {
>  		compatible = "i2c-gpio";
>  		#address-cells = <1>;
> @@ -247,6 +274,13 @@ touchkey_irq_pin: touchkey-irq-state {

This label from the context seems not to be present in -next, FWIW

>  		drive-strength = <2>;
>  		bias-disable;
>  	};
> +
> +	cam_flash_en: cam-flash-en-state {
> +		pins = "gpio3";

Please keep the pinctrl entries sorted by the GPIO index

Konrad