linux-kernel - [PATCH 10/20] gpio: pca953x: Add optional reset gpio control

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Date:   Thu, 29 Dec 2016 14:27:25 -0800
From:   Steve Longerbeam <slongerbeam@...il.com>
To:     shawnguo@...nel.org, kernel@...gutronix.de, fabio.estevam@....com,
        robh+dt@...nel.org, mark.rutland@....com, linux@...linux.org.uk,
        linus.walleij@...aro.org, gnurou@...il.com, mchehab@...nel.org,
        gregkh@...uxfoundation.org, p.zabel@...gutronix.de
Cc:     linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...verdev.osuosl.org,
        Steve Longerbeam <steve_longerbeam@...tor.com>
Subject: [PATCH 10/20] gpio: pca953x: Add optional reset gpio control

Add optional reset-gpios pin control. If present, de-assert the
specified reset gpio pin to bring the chip out of reset.

Signed-off-by: Steve Longerbeam <steve_longerbeam@...tor.com>
Cc: Linus Walleij <linus.walleij@...aro.org>
Cc: Alexandre Courbot <gnurou@...il.com>
Cc: linux-gpio@...r.kernel.org
Cc: linux-kernel@...r.kernel.org

---

v2:
- documented optional reset-gpios property in
  Documentation/devicetree/bindings/gpio/gpio-pca953x.txt.
---
 Documentation/devicetree/bindings/gpio/gpio-pca953x.txt |  4 ++++
 drivers/gpio/gpio-pca953x.c                             | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
index 08dd15f..da54f4c 100644
--- a/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio-pca953x.txt
@@ -29,6 +29,10 @@ Required properties:
 	onsemi,pca9654
 	exar,xra1202
 
+Optional properties:
+ - reset-gpios: GPIO specification for the RESET input
+
+
 Example:
 
 
diff --git a/drivers/gpio/gpio-pca953x.c b/drivers/gpio/gpio-pca953x.c
index d5d72d8..d1c0bd5 100644
--- a/drivers/gpio/gpio-pca953x.c
+++ b/drivers/gpio/gpio-pca953x.c
@@ -22,6 +22,7 @@
 #include <linux/of_platform.h>
 #include <linux/acpi.h>
 #include <linux/regulator/consumer.h>
+#include <linux/gpio/consumer.h>
 
 #define PCA953X_INPUT		0
 #define PCA953X_OUTPUT		1
@@ -133,6 +134,7 @@ struct pca953x_chip {
 	const char *const *names;
 	unsigned long driver_data;
 	struct regulator *regulator;
+	struct gpio_desc *reset_gpio;
 
 	const struct pca953x_reg_config *regs;
 
@@ -756,6 +758,21 @@ static int pca953x_probe(struct i2c_client *client,
 	} else {
 		chip->gpio_start = -1;
 		irq_base = 0;
+
+		/* see if we need to de-assert a reset pin */
+		chip->reset_gpio = devm_gpiod_get_optional(&client->dev,
+							   "reset",
+							   GPIOD_OUT_LOW);
+		if (IS_ERR(chip->reset_gpio)) {
+			dev_err(&client->dev, "request for reset pin failed\n");
+			return PTR_ERR(chip->reset_gpio);
+		}
+
+		if (chip->reset_gpio) {
+			/* bring chip out of reset */
+			dev_info(&client->dev, "releasing reset\n");
+			gpiod_set_value(chip->reset_gpio, 0);
+		}
 	}
 
 	chip->client = client;
-- 
2.7.4