[PATCH] [v2] iio: light: bh1750: Add hardware reset support via GPIO

[Sergio Perez <sergio@pereznus.es>]

Some BH1750 sensors require a hardware reset before they can be
detected on the I2C bus. This patch adds support for an optional
reset GPIO that can be specified in the device tree.

The reset sequence pulls the GPIO low and then high before
initializing the sensor, which enables proper detection with
tools like i2cdetect.

Signed-off-by: Sergio Perez <sergio@pereznus.es>
---
 .../devicetree/bindings/iio/light/bh1750.yaml |  7 +++++-
 drivers/iio/light/bh1750.c                    | 24 ++++++++++++++++++-
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/iio/light/bh1750.yaml b/Documentation/devicetree/bindings/iio/light/bh1750.yaml
index 1a88b3c253d5..12c97d761aa4 100644
--- a/Documentation/devicetree/bindings/iio/light/bh1750.yaml
+++ b/Documentation/devicetree/bindings/iio/light/bh1750.yaml
@@ -24,6 +24,10 @@ properties:
   reg:
     maxItems: 1
 
+  reset-gpios:
+    description: GPIO connected to the sensor's reset line (active low)
+    maxItems: 1
+
 required:
   - compatible
   - reg
@@ -39,7 +43,8 @@ examples:
       light-sensor@23 {
         compatible = "rohm,bh1750";
         reg = <0x23>;
+        reset-gpios = <&gpio2 17 GPIO_ACTIVE_HIGH>;
       };
     };
 
-...
+...
\ No newline at end of file
diff --git a/drivers/iio/light/bh1750.c b/drivers/iio/light/bh1750.c
index 4b869fa9e5b1..55e2be0323ef 100644
--- a/drivers/iio/light/bh1750.c
+++ b/drivers/iio/light/bh1750.c
@@ -22,12 +22,16 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/module.h>
+#include <linux/gpio/consumer.h>
 
 #define BH1750_POWER_DOWN		0x00
 #define BH1750_ONE_TIME_H_RES_MODE	0x20 /* auto-mode for BH1721 */
 #define BH1750_CHANGE_INT_TIME_H_BIT	0x40
 #define BH1750_CHANGE_INT_TIME_L_BIT	0x60
 
+/* Define the reset delay time in microseconds */
+#define BH1750_RESET_DELAY_US 10000 /* 10ms */
+
 enum {
 	BH1710,
 	BH1721,
@@ -40,6 +44,7 @@ struct bh1750_data {
 	struct mutex lock;
 	const struct bh1750_chip_info *chip_info;
 	u16 mtreg;
+	struct gpio_desc *reset_gpio;
 };
 
 struct bh1750_chip_info {
@@ -248,6 +253,23 @@ static int bh1750_probe(struct i2c_client *client)
 	data->client = client;
 	data->chip_info = &bh1750_chip_info_tbl[id->driver_data];
 
+	/* Get reset GPIO from device tree */
+	data->reset_gpio = devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR(data->reset_gpio))
+		return dev_err_probe(&client->dev, PTR_ERR(data->reset_gpio),
+							"Failed to get reset GPIO\n");
+
+	/* Perform hardware reset if GPIO is provided */
+	if (data->reset_gpio) {
+		/* Perform reset sequence: low-high */
+		gpiod_set_value_cansleep(data->reset_gpio, 0);
+		fsleep(BH1750_RESET_DELAY_US);
+		gpiod_set_value_cansleep(data->reset_gpio, 1);
+		fsleep(BH1750_RESET_DELAY_US);
+
+		dev_dbg(&client->dev, "BH1750 reset completed via GPIO\n");
+	}
+
 	usec = data->chip_info->mtreg_to_usec * data->chip_info->mtreg_default;
 	ret = bh1750_change_int_time(data, usec);
 	if (ret < 0)
@@ -329,4 +351,4 @@ module_i2c_driver(bh1750_driver);
 
 MODULE_AUTHOR("Tomasz Duszynski <tduszyns@gmail.com>");
 MODULE_DESCRIPTION("ROHM BH1710/BH1715/BH1721/BH1750/BH1751 als driver");
-MODULE_LICENSE("GPL v2");
+MODULE_LICENSE("GPL v2");
\ No newline at end of file
-- 
2.47.1