linux-kernel - [PATCH v2 08/16] iio: adc: ad7768-1: Add reset gpio

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Message-ID: <722340b0efff3ed22a763ce6581c96ca403316d8.1737985435.git.Jonathan.Santos@analog.com>
Date: Mon, 27 Jan 2025 12:12:55 -0300
From: Jonathan Santos <Jonathan.Santos@...log.com>
To: <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC: Sergiu Cuciurean <sergiu.cuciurean@...log.com>, <lars@...afoo.de>,
        <Michael.Hennerich@...log.com>, <marcelo.schmitt@...log.com>,
        <jic23@...nel.org>, <robh@...nel.org>, <krzk+dt@...nel.org>,
        <conor+dt@...nel.org>, <jonath4nns@...il.com>,
        <marcelo.schmitt1@...il.com>
Subject: [PATCH v2 08/16] iio: adc: ad7768-1: Add reset gpio

From: Sergiu Cuciurean <sergiu.cuciurean@...log.com>

Depending on the controller, the default state of a gpio can vary. This
change excludes the probability that the dafult state of the ADC reset
gpio will be HIGH if it will be passed as reference in the devicetree.

Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@...log.com>
---
v2 Changes:
* Replaced usleep_range() for fsleep() and gpiod_direction_output() for 
  gpiod_set_value_cansleep().
* Reset via SPI register is performed if the Reset GPIO is not defined. 
---
 drivers/iio/adc/ad7768-1.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c
index fb8d6fae5f8a..17a49bf74637 100644
--- a/drivers/iio/adc/ad7768-1.c
+++ b/drivers/iio/adc/ad7768-1.c
@@ -163,6 +163,7 @@ struct ad7768_state {
 	struct completion completion;
 	struct iio_trigger *trig;
 	struct gpio_desc *gpio_sync_in;
+	struct gpio_desc *gpio_reset;
 	const char *labels[ARRAY_SIZE(ad7768_channels)];
 	/*
 	 * DMA (thus cache coherency maintenance) may require the
@@ -453,19 +454,30 @@ static int ad7768_setup(struct ad7768_state *st)
 {
 	int ret;
 
-	/*
-	 * Two writes to the SPI_RESET[1:0] bits are required to initiate
-	 * a software reset. The bits must first be set to 11, and then
-	 * to 10. When the sequence is detected, the reset occurs.
-	 * See the datasheet, page 70.
-	 */
-	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x3);
-	if (ret)
-		return ret;
+	st->gpio_reset = devm_gpiod_get_optional(&st->spi->dev, "reset",
+						 GPIOD_OUT_HIGH);
+	if (IS_ERR(st->gpio_reset))
+		return PTR_ERR(st->gpio_reset);
 
-	ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x2);
-	if (ret)
-		return ret;
+	if (st->gpio_reset) {
+		fsleep(10);
+		gpiod_set_value_cansleep(st->gpio_reset, 0);
+		fsleep(10);
+	} else {
+		/*
+		 * Two writes to the SPI_RESET[1:0] bits are required to initiate
+		 * a software reset. The bits must first be set to 11, and then
+		 * to 10. When the sequence is detected, the reset occurs.
+		 * See the datasheet, page 70.
+		 */
+		ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x3);
+		if (ret)
+			return ret;
+
+		ret = regmap_write(st->regmap, AD7768_REG_SYNC_RESET, 0x2);
+		if (ret)
+			return ret;
+	}
 
 	st->gpio_sync_in = devm_gpiod_get(&st->spi->dev, "adi,sync-in",
 					  GPIOD_OUT_LOW);
-- 
2.34.1