[PATCH 5/5] iio: addac: ad74413r: add support for reset-gpio

[Rasmus Villemoes <linux@rasmusvillemoes.dk>]

We have a board where the reset pin of the ad74412 is connected to a
gpio, but also pulled low by default. Hence to get the chip out of
reset, the driver needs to know about that gpio and set it high before
attempting to communicate with it.

When a reset-gpio is given in device tree, use that instead of the
software reset. According to the data sheet, the two methods are
functionally equivalent.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 drivers/iio/addac/ad74413r.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/iio/addac/ad74413r.c b/drivers/iio/addac/ad74413r.c
index 9f77d2f514de..af09d43f921c 100644
--- a/drivers/iio/addac/ad74413r.c
+++ b/drivers/iio/addac/ad74413r.c
@@ -71,6 +71,7 @@ struct ad74413r_state {
 	struct regmap			*regmap;
 	struct device			*dev;
 	struct iio_trigger		*trig;
+	struct gpio_desc		*reset_gpio;
 
 	size_t			adc_active_channels;
 	struct spi_message	adc_samples_msg;
@@ -393,6 +394,13 @@ static int ad74413r_reset(struct ad74413r_state *st)
 {
 	int ret;
 
+	if (st->reset_gpio) {
+		gpiod_set_value_cansleep(st->reset_gpio, 1);
+		fsleep(50);
+		gpiod_set_value_cansleep(st->reset_gpio, 0);
+		return 0;
+	}
+
 	ret = regmap_write(st->regmap, AD74413R_REG_CMD_KEY,
 			   AD74413R_CMD_KEY_RESET1);
 	if (ret)
@@ -1316,6 +1324,10 @@ static int ad74413r_probe(struct spi_device *spi)
 	if (IS_ERR(st->regmap))
 		return PTR_ERR(st->regmap);
 
+	st->reset_gpio = devm_gpiod_get_optional(st->dev, "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(st->reset_gpio))
+		return PTR_ERR(st->reset_gpio);
+
 	st->refin_reg = devm_regulator_get_optional(st->dev, "refin");
 	if (IS_ERR(st->refin_reg)) {
 		ret = PTR_ERR(st->refin_reg);
-- 
2.37.2