* [PATCH v4 1/3] dt-bindings: leds: rt8515: Support single-GPIO flash ICs with vin supply
2026-03-31 17:08 [PATCH v4 0/3] Samsung Expressatt: Camera Flash Rudraksha Gupta via B4 Relay
@ 2026-03-31 17:08 ` Rudraksha Gupta via B4 Relay
2026-03-31 17:08 ` [PATCH v4 2/3] leds: flash: " Rudraksha Gupta via B4 Relay
2026-03-31 17:08 ` [PATCH v4 3/3] ARM: dts: qcom: msm8960: expressatt: Add camera flash Rudraksha Gupta via B4 Relay
2 siblings, 0 replies; 8+ messages in thread
From: Rudraksha Gupta via B4 Relay @ 2026-03-31 17:08 UTC (permalink / raw)
To: Lee Jones, Pavel Machek, Rob Herring, Krzysztof Kozlowski,
Conor Dooley, Linus Walleij, Bjorn Andersson, Konrad Dybcio,
Liam Girdwood, Mark Brown
Cc: linux-leds, devicetree, linux-kernel, linux-arm-msm, phone-devel,
Rudraksha Gupta, Conor Dooley
From: Rudraksha Gupta <guptarud@gmail.com>
Some flash ICs use the same one-wire pulse-count protocol as the RT8515
but have only a single enable line for both flash and torch modes, plus
an optional input voltage supply (e.g. a GPIO-controlled fixed
regulator) that gates power to the chip.
Make ent-gpios optional and add a vin-supply property to support these
variants. Add a oneOf constraint requiring exactly one of ent-gpios or
vin-supply. Add a binding example showing the single-GPIO configuration
with an input supply.
Assisted-by: Claude:claude-opus-4.6
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
---
.../devicetree/bindings/leds/richtek,rt8515.yaml | 34 +++++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
index 0356371a6b01..ab3c5139132c 100644
--- a/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
+++ b/Documentation/devicetree/bindings/leds/richtek,rt8515.yaml
@@ -15,6 +15,10 @@ description: |
current for each mode is defined in hardware using two resistors
RFS and RTS.
+ Some flash ICs use the same one-wire pulse-count protocol but have
+ only a single enable line for both flash and torch modes. For these
+ single-channel variants, only enf-gpios is needed.
+
properties:
compatible:
const: richtek,rt8515
@@ -26,6 +30,11 @@ properties:
ent-gpios:
maxItems: 1
description: A connection to the 'ENT' (enable torch) pin.
+ Not present on single-channel flash ICs that use only one enable
+ line for both flash and torch modes.
+
+ vin-supply:
+ description: Optional input supply for the flash IC.
richtek,rfs-ohms:
minimum: 7680
@@ -81,10 +90,15 @@ properties:
required:
- compatible
- - ent-gpios
- enf-gpios
- led
+oneOf:
+ - required:
+ - ent-gpios
+ - required:
+ - vin-supply
+
additionalProperties: false
examples:
@@ -108,4 +122,22 @@ examples:
};
};
+ - |
+ /* Single-channel flash IC with input supply */
+ #include <dt-bindings/gpio/gpio.h>
+ #include <dt-bindings/leds/common.h>
+
+ led-controller {
+ compatible = "richtek,rt8515";
+ enf-gpios = <&tlmm 3 GPIO_ACTIVE_HIGH>;
+ vin-supply = <&flash_reg>;
+ richtek,rfs-ohms = <16000>;
+
+ led {
+ function = LED_FUNCTION_FLASH;
+ color = <LED_COLOR_ID_WHITE>;
+ flash-max-timeout-us = <250000>;
+ };
+ };
+
...
--
2.53.0
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v4 2/3] leds: flash: rt8515: Support single-GPIO flash ICs with vin supply
2026-03-31 17:08 [PATCH v4 0/3] Samsung Expressatt: Camera Flash Rudraksha Gupta via B4 Relay
2026-03-31 17:08 ` [PATCH v4 1/3] dt-bindings: leds: rt8515: Support single-GPIO flash ICs with vin supply Rudraksha Gupta via B4 Relay
@ 2026-03-31 17:08 ` Rudraksha Gupta via B4 Relay
2026-03-31 18:17 ` Linus Walleij
2026-03-31 17:08 ` [PATCH v4 3/3] ARM: dts: qcom: msm8960: expressatt: Add camera flash Rudraksha Gupta via B4 Relay
2 siblings, 1 reply; 8+ messages in thread
From: Rudraksha Gupta via B4 Relay @ 2026-03-31 17:08 UTC (permalink / raw)
To: Lee Jones, Pavel Machek, Rob Herring, Krzysztof Kozlowski,
Conor Dooley, Linus Walleij, Bjorn Andersson, Konrad Dybcio,
Liam Girdwood, Mark Brown
Cc: linux-leds, devicetree, linux-kernel, linux-arm-msm, phone-devel,
Rudraksha Gupta
From: Rudraksha Gupta <guptarud@gmail.com>
Extend the RT8515 driver to support flash ICs that use only a single
GPIO for both flash and torch modes (no separate ENT pin), with an
optional vin regulator that gates power to the flash IC.
When vin-supply is provided, the driver enables the regulator before
activating the LED and disables it when turning off.
Make ent-gpios optional and validate at probe time that exactly one of
ent-gpios or vin-supply is provided. When ent-gpios is absent, the
driver uses enf-gpios for both flash and torch brightness control.
Assisted-by: Claude:claude-opus-4.6
Signed-off-by: Rudraksha Gupta <guptarud@gmail.com>
---
drivers/leds/flash/leds-rt8515.c | 100 ++++++++++++++++++++++++++++++++-------
1 file changed, 83 insertions(+), 17 deletions(-)
diff --git a/drivers/leds/flash/leds-rt8515.c b/drivers/leds/flash/leds-rt8515.c
index f6b439674c03..c7f0bdf804a7 100644
--- a/drivers/leds/flash/leds-rt8515.c
+++ b/drivers/leds/flash/leds-rt8515.c
@@ -63,16 +63,44 @@ static struct rt8515 *to_rt8515(struct led_classdev_flash *fled)
return container_of(fled, struct rt8515, fled);
}
-static void rt8515_gpio_led_off(struct rt8515 *rt)
+static int rt8515_gpio_led_off(struct rt8515 *rt)
{
+ int ret;
+
gpiod_set_value(rt->enable_flash, 0);
- gpiod_set_value(rt->enable_torch, 0);
+ if (rt->enable_torch)
+ gpiod_set_value(rt->enable_torch, 0);
+
+ /* Disable regulator */
+ ret = regulator_is_enabled(rt->reg);
+ if (ret < 0)
+ return ret;
+ if (ret > 0)
+ return regulator_disable(rt->reg);
+
+ return 0;
}
-static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
- int brightness)
+static int rt8515_gpio_brightness_commit(struct rt8515 *rt,
+ struct gpio_desc *gpiod,
+ int brightness)
{
int i;
+ int ret;
+
+ /*
+ * Reset the IC to start brightness from zero,
+ * then re-enable and pulse to the desired level.
+ */
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ return ret;
+ /* IC needs time to reset its brightness counter */
+ usleep_range(100, 200);
+ /* Enable regulator */
+ ret = regulator_enable(rt->reg);
+ if (ret)
+ return ret;
/*
* Toggling a GPIO line with a small delay increases the
@@ -84,6 +112,8 @@ static void rt8515_gpio_brightness_commit(struct gpio_desc *gpiod,
gpiod_set_value(gpiod, 1);
udelay(1);
}
+
+ return 0;
}
/* This is setting the torch light level */
@@ -92,23 +122,39 @@ static int rt8515_led_brightness_set(struct led_classdev *led,
{
struct led_classdev_flash *fled = lcdev_to_flcdev(led);
struct rt8515 *rt = to_rt8515(fled);
+ int ret = 0;
mutex_lock(&rt->lock);
if (brightness == LED_OFF) {
/* Off */
- rt8515_gpio_led_off(rt);
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ goto out;
} else if (brightness < RT8515_TORCH_MAX) {
- /* Step it up to movie mode brightness using the flash pin */
- rt8515_gpio_brightness_commit(rt->enable_torch, brightness);
+ /*
+ * Step it up to movie mode brightness.
+ * If there is no separate torch pin, use the flash pin
+ * for torch as well.
+ */
+ ret = rt8515_gpio_brightness_commit(rt, rt->enable_torch ?
+ rt->enable_torch : rt->enable_flash, brightness);
+ if (ret)
+ goto out;
} else {
- /* Max torch brightness requested */
- gpiod_set_value(rt->enable_torch, 1);
+ /*
+ * Max torch brightness requested.
+ * If there is no separate torch pin, use the flash pin
+ * for torch as well.
+ */
+ gpiod_set_value(rt->enable_torch ? rt->enable_torch :
+ rt->enable_flash, 1);
}
+out:
mutex_unlock(&rt->lock);
- return 0;
+ return ret;
}
static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
@@ -117,27 +163,33 @@ static int rt8515_led_flash_strobe_set(struct led_classdev_flash *fled,
struct rt8515 *rt = to_rt8515(fled);
struct led_flash_setting *timeout = &fled->timeout;
int brightness = rt->flash_max_intensity;
+ int ret = 0;
mutex_lock(&rt->lock);
if (state) {
/* Enable LED flash mode and set brightness */
- rt8515_gpio_brightness_commit(rt->enable_flash, brightness);
+ ret = rt8515_gpio_brightness_commit(rt, rt->enable_flash, brightness);
+ if (ret)
+ goto out;
/* Set timeout */
mod_timer(&rt->powerdown_timer,
jiffies + usecs_to_jiffies(timeout->val));
} else {
timer_delete_sync(&rt->powerdown_timer);
/* Turn the LED off */
- rt8515_gpio_led_off(rt);
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ goto out;
}
fled->led_cdev.brightness = LED_OFF;
/* After this the torch LED will be disabled */
+out:
mutex_unlock(&rt->lock);
- return 0;
+ return ret;
}
static int rt8515_led_flash_strobe_get(struct led_classdev_flash *fled,
@@ -166,9 +218,12 @@ static const struct led_flash_ops rt8515_flash_ops = {
static void rt8515_powerdown_timer(struct timer_list *t)
{
struct rt8515 *rt = timer_container_of(rt, t, powerdown_timer);
+ int ret;
/* Turn the LED off */
- rt8515_gpio_led_off(rt);
+ ret = rt8515_gpio_led_off(rt);
+ if (ret)
+ dev_err(rt->dev, "failed to turn off LED (%d)\n", ret);
}
static void rt8515_init_flash_timeout(struct rt8515 *rt)
@@ -298,12 +353,18 @@ static int rt8515_probe(struct platform_device *pdev)
return dev_err_probe(dev, PTR_ERR(rt->enable_flash),
"cannot get ENF (enable flash) GPIO\n");
- /* ENT - Enable Torch line */
- rt->enable_torch = devm_gpiod_get(dev, "ent", GPIOD_OUT_LOW);
+ /* ENT - Enable Torch line (optional for single-GPIO flash ICs) */
+ rt->enable_torch = devm_gpiod_get_optional(dev, "ent", GPIOD_OUT_LOW);
if (IS_ERR(rt->enable_torch))
return dev_err_probe(dev, PTR_ERR(rt->enable_torch),
"cannot get ENT (enable torch) GPIO\n");
+ /* Optional VIN supply */
+ rt->reg = devm_regulator_get(dev, "vin");
+ if (IS_ERR(rt->reg))
+ return dev_err_probe(dev, PTR_ERR(rt->reg),
+ "failed to get vin supply\n");
+
child = device_get_next_child_node(dev, NULL);
if (!child) {
dev_err(dev,
@@ -333,7 +394,12 @@ static int rt8515_probe(struct platform_device *pdev)
fled->ops = &rt8515_flash_ops;
- led->max_brightness = rt->torch_max_intensity;
+ /*
+ * If there is no separate torch pin, use the flash max intensity
+ * as the max brightness instead.
+ */
+ led->max_brightness = rt->enable_torch ?
+ rt->torch_max_intensity : rt->flash_max_intensity;
led->brightness_set_blocking = rt8515_led_brightness_set;
led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;
--
2.53.0
^ permalink raw reply related [flat|nested] 8+ messages in thread* [PATCH v4 3/3] ARM: dts: qcom: msm8960: expressatt: Add camera flash
2026-03-31 17:08 [PATCH v4 0/3] Samsung Expressatt: Camera Flash Rudraksha Gupta via B4 Relay
2026-03-31 17:08 ` [PATCH v4 1/3] dt-bindings: leds: rt8515: Support single-GPIO flash ICs with vin supply Rudraksha Gupta via B4 Relay
2026-03-31 17:08 ` [PATCH v4 2/3] leds: flash: " Rudraksha Gupta via B4 Relay
@ 2026-03-31 17:08 ` Rudraksha Gupta via B4 Relay
2026-03-31 18:24 ` Dmitry Baryshkov
2 siblings, 1 reply; 8+ messages in thread
From: Rudraksha Gupta via B4 Relay @ 2026-03-31 17:08 UTC (permalink / raw)
To: Lee Jones, Pavel Machek, Rob Herring, Krzysztof Kozlowski,
Conor Dooley, Linus Walleij, Bjorn Andersson, Konrad Dybcio,
Liam Girdwood, Mark Brown
Cc: linux-leds, devicetree, linux-kernel, linux-arm-msm, phone-devel,
Rudraksha Gupta, David Heidelberg, Konrad Dybcio
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
Assisted-by: Claude:claude-opus-4.6
Reviewed-by: David Heidelberg <david@ixit.cz>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
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..35514fd53e3d 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;
};
+ vreg_flash: regulator-flash {
+ compatible = "regulator-fixed";
+ regulator-name = "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";
+ };
+
+ led-controller {
+ compatible = "richtek,rt8515";
+ enf-gpios = <&tlmm 3 GPIO_ACTIVE_HIGH>;
+ vin-supply = <&vreg_flash>;
+ 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>;
@@ -172,6 +199,13 @@ touchscreen@4a {
};
&tlmm {
+ cam_flash_en: cam-flash-en-state {
+ pins = "gpio3";
+ function = "gpio";
+ drive-strength = <16>;
+ bias-pull-down;
+ };
+
spi1_default: spi1-default-state {
mosi-pins {
pins = "gpio6";
@@ -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
^ permalink raw reply related [flat|nested] 8+ messages in thread