[PATCH v5 06/12] iio: dac: ad5686: consume optional reset signal

[Rodrigo Alencar via B4 Relay <devnull+rodrigo.alencar.analog.com@kernel.org>]

From: Rodrigo Alencar <rodrigo.alencar@analog.com>

Add RESET pin GPIO support through an optional reset control, which is
local to the probe function. A reset pulse is manually generated after
the device is powered up.

Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
---
 drivers/iio/dac/ad5686.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index e2ebabca6887..8ad8931a3d7f 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -15,6 +15,7 @@
 #include <linux/kstrtox.h>
 #include <linux/module.h>
 #include <linux/regulator/consumer.h>
+#include <linux/reset.h>
 #include <linux/sysfs.h>
 #include <linux/wordpart.h>
 
@@ -472,6 +473,7 @@ int ad5686_probe(struct device *dev,
 		 const struct ad5686_chip_info *chip_info,
 		 const char *name, const struct ad5686_bus_ops *ops)
 {
+	struct reset_control *rstc;
 	struct ad5686_state *st;
 	struct iio_dev *indio_dev;
 	int ret, i;
@@ -486,6 +488,11 @@ int ad5686_probe(struct device *dev,
 	st->ops = ops;
 	st->chip_info = chip_info;
 
+	rstc = devm_reset_control_get_optional_exclusive(dev, NULL);
+	if (IS_ERR(rstc))
+		return dev_err_probe(dev, PTR_ERR(rstc),
+				     "Failed to get reset control\n");
+
 	ret = devm_regulator_get_enable(dev, "vdd");
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to enable vdd supply\n");
@@ -509,6 +516,11 @@ int ad5686_probe(struct device *dev,
 	/* 4.5us power-up time: Datasheet Table 4: Timing Characteristics */
 	fsleep(5);
 
+	/* 1us >> 30ns reset pulse activation time: Datasheet Table 4 */
+	reset_control_assert(rstc);
+	fsleep(1);
+	reset_control_deassert(rstc);
+
 	/* Initialize masks to all ones */
 	st->pwr_down_mask = ~0;
 	st->pwr_down_mode = ~0;

-- 
2.43.0