[PATCH 4/6] iio: dac: ad5791: Add reset, clr and ldac gpios

[ahaslam@xxxxxxxxxxxx]

From: Axel Haslam <ahaslam@xxxxxxxxxxxx>

The ad7591 has reset, clr and ldac gpios. For the DAC to output data
continuously written to the data register the state of these gpios needs
to be set by the driver.

Add these gpios to the driver making them optional in case they are fixed
on the pcb.

Signed-off-by: Axel Haslam <ahaslam@xxxxxxxxxxxx>
---
 drivers/iio/dac/ad5791.c | 31 ++++++++++++++++++++++++++++---
 1 file changed, 28 insertions(+), 3 deletions(-)

diff --git a/drivers/iio/dac/ad5791.c b/drivers/iio/dac/ad5791.c
index a11e81211669..a7cf19346cf0 100644
--- a/drivers/iio/dac/ad5791.c
+++ b/drivers/iio/dac/ad5791.c
@@ -9,6 +9,7 @@
 #include <linux/interrupt.h>
 #include <linux/fs.h>
 #include <linux/device.h>
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/spi/spi.h>
 #include <linux/slab.h>
@@ -87,6 +88,9 @@ struct ad5791_state {
 	struct spi_device		*spi;
 	struct regulator		*reg_vdd;
 	struct regulator		*reg_vss;
+	struct gpio_desc		*gpio_reset;
+	struct gpio_desc		*gpio_clear;
+	struct gpio_desc		*gpio_ldac;
 	const struct ad5791_chip_info	*chip_info;
 	unsigned short			vref_mv;
 	unsigned int			vref_neg_mv;
@@ -336,6 +340,22 @@ static int ad5791_probe(struct spi_device *spi)
 	if (!indio_dev)
 		return -ENOMEM;
 	st = iio_priv(indio_dev);
+
+	st->gpio_reset = devm_gpiod_get_optional(&spi->dev, "reset",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(st->gpio_reset))
+		return PTR_ERR(st->gpio_reset);
+
+	st->gpio_clear = devm_gpiod_get_optional(&spi->dev, "clear",
+						 GPIOD_OUT_LOW);
+	if (IS_ERR(st->gpio_clear))
+		return PTR_ERR(st->gpio_clear);
+
+	st->gpio_ldac = devm_gpiod_get_optional(&spi->dev, "ldac",
+						GPIOD_OUT_HIGH);
+	if (IS_ERR(st->gpio_ldac))
+		return PTR_ERR(st->gpio_ldac);
+
 	st->reg_vdd = devm_regulator_get(&spi->dev, "vdd");
 	if (!IS_ERR(st->reg_vdd)) {
 		ret = regulator_enable(st->reg_vdd);
@@ -381,9 +401,14 @@ static int ad5791_probe(struct spi_device *spi)
 		dev_warn(&spi->dev, "reference voltage unspecified\n");
 	}
 
-	ret = ad5791_spi_write(st, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
-	if (ret)
-		goto error_disable_reg_neg;
+	if (st->gpio_reset) {
+		fsleep(20);
+		gpiod_set_value_cansleep(st->gpio_reset, 0);
+	} else {
+		ret = ad5791_spi_write(st, AD5791_ADDR_SW_CTRL, AD5791_SWCTRL_RESET);
+		if (ret)
+			goto error_disable_reg_neg;
+	}
 
 	st->chip_info = spi_get_device_match_data(spi);
 	if (!st->chip_info)
-- 
2.34.1