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

[Rodrigo Alencar via B4 Relay]

From: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>

Add RESET pin GPIO support through an optional reset control, which is
local to the probe function. Also, include delays for power-up time and
reset pulse width.

Signed-off-by: Rodrigo Alencar <rodrigo.alencar@xxxxxxxxxx>
---
 drivers/iio/dac/ad5686.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/iio/dac/ad5686.c b/drivers/iio/dac/ad5686.c
index 4a8c587ff116..345ca2436332 100644
--- a/drivers/iio/dac/ad5686.c
+++ b/drivers/iio/dac/ad5686.c
@@ -8,12 +8,14 @@
 #include <linux/array_size.h>
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
+#include <linux/delay.h>
 #include <linux/dev_printk.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #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>
 
@@ -471,6 +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;
@@ -506,6 +509,16 @@ int ad5686_probe(struct device *dev,
 		return dev_err_probe(dev, -EINVAL,
 				     "invalid or not provided vref voltage\n");
 
+	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");
+
+	udelay(5); /* power-up time */
+	reset_control_assert(rstc);
+	udelay(1); /* reset pulse: comfortably bigger than the spec */
+	reset_control_deassert(rstc);
+
 	/* Initialize masks to all ones */
 	st->pwr_down_mask = ~0;
 	st->pwr_down_mode = ~0;

-- 
2.43.0