i2c: pca954x: Add reset GPIO support

If a reset GPIO support is specified, request the GPIO and get the chip
out of reset at probe time.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
index 2880c38543de..e835304e7b5a 100644
--- a/drivers/i2c/muxes/i2c-mux-pca954x.c
+++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
@@ -36,11 +36,13 @@
  */
 
 #include <linux/device.h>
+#include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/i2c-mux.h>
 #include <linux/i2c/pca954x.h>
 #include <linux/init.h>
 #include <linux/module.h>
+#include <linux/of_gpio.h>
 #include <linux/slab.h>
 
 #define PCA954X_MAX_NCHANS 8
@@ -185,6 +187,7 @@ static int pca954x_probe(struct i2c_client *client,
 {
         struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
         struct pca954x_platform_data *pdata = dev_get_platdata(&client->dev);
+        struct device_node *np = client->dev.of_node;
         int num, force, class;
         struct pca954x *data;
         int ret;
@@ -198,6 +201,22 @@ static int pca954x_probe(struct i2c_client *client,
 
         i2c_set_clientdata(client, data);
 
+        if (IS_ENABLED(CONFIG_OF) && np) {
+                enum of_gpio_flags flags;
+                int gpio;
+
+                /* Get the mux out of reset if a reset GPIO is specified. */
+                gpio = of_get_named_gpio_flags(np, "reset-gpio", 0, &flags);
+                if (gpio_is_valid(gpio)) {
+                        ret = devm_gpio_request_one(&client->dev, gpio,
+                                        flags & OF_GPIO_ACTIVE_LOW ?
+                                        GPIOF_OUT_INIT_HIGH : GPIOF_OUT_INIT_LOW,
+                                        "pca954x reset");
+                        if (ret < 0)
+                                return ret;
+                }
+        }
+
         /* Write the mux register at addr to verify
          * that the mux is in fact present. This also
          * initializes the mux to disconnected state.