[PATCH v3 2/3] leds: flash: rt8515: Support single-GPIO flash ICs with vin supply

Rudraksha Gupta via B4 Relay
2026-03-26T07:57:33Z

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 | 90 ++++++++++++++++++++++++++++++++--------
1 file changed, 72 insertions(+), 18 deletions(-)

diff --git a/drivers/leds/flash/leds-rt8515.c b/drivers/leds/flash/leds-rt8515.c
index f6b439674c03..739cac8789c8 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_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_set_flash_brightness(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_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
@@ -84,31 +112,41 @@ 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 */
-static int rt8515_led_brightness_set(struct led_classdev *led,
+static int rt8515_set_brightness(struct led_classdev *led,
enum led_brightness brightness)
{
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_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 */
+ ret = rt8515_set_flash_brightness(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);
+ 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 +155,33 @@ 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_set_flash_brightness(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_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 +210,12 @@ 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_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 +345,18 @@ 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,
@@ -333,8 +386,9 @@ static int rt8515_probe(struct platform_device *pdev)

fled->ops = &rt8515_flash_ops;

- led->max_brightness = rt->torch_max_intensity;
- led->brightness_set_blocking = rt8515_led_brightness_set;
+ led->max_brightness = rt->enable_torch ?
+ rt->torch_max_intensity : rt->flash_max_intensity;
+ led->brightness_set_blocking = rt8515_set_brightness;
led->flags |= LED_CORE_SUSPENDRESUME | LED_DEV_CAP_FLASH;

mutex_init(&rt->lock);

--
2.53.0