Input: sx8654 - add reset-gpio support

The sx8654 features a NRST input which may be connected to a GPIO.
Therefore add support for hard-resetting the sx8654 via this NRST.

If the reset-gpio property is provided the sx8654 is resetted via NRST
instead of the soft-reset via I2C.

Signed-off-by: Richard Leitner <richard.leitner@skidata.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/Documentation/devicetree/bindings/input/touchscreen/sx8654.txt b/Documentation/devicetree/bindings/input/touchscreen/sx8654.txt
index 4886c4aa2906f31e1fd39aad9f89481b6bebd33d..ca521d8f7d6591660c513fd5dc8d3f2960555b15 100644 (file)
--- a/Documentation/devicetree/bindings/input/touchscreen/sx8654.txt
+++ b/Documentation/devicetree/bindings/input/touchscreen/sx8654.txt
@@ -5,6 +5,9 @@ Required properties:
 - reg: i2c slave address
 - interrupts: touch controller interrupt
 
+Optional properties:
+ - reset-gpios: GPIO specification for the NRST input
+
 Example:
 
        sx8654@48 {
@@ -12,4 +15,5 @@ Example:
                reg = <0x48>;
                interrupt-parent = <&gpio6>;
                interrupts = <3 IRQ_TYPE_EDGE_FALLING>;
+               reset-gpios = <&gpio4 2 GPIO_ACTIVE_LOW>;
        };

diff --git a/drivers/input/touchscreen/sx8654.c b/drivers/input/touchscreen/sx8654.c
index ed29db3ec731e582a4fdd919e37c7be7e2af135e..ab5cbf7e0879c9ae68a01ba7c5ebc7a597cdf515 100644 (file)
--- a/drivers/input/touchscreen/sx8654.c
+++ b/drivers/input/touchscreen/sx8654.c
@@ -27,12 +27,14 @@
  *  published by the Free Software Foundation.
  */
 
-#include <linux/input.h>
-#include <linux/module.h>
-#include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
+#include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
 
 /* register addresses */
 #define I2C_REG_TOUCH0                 0x00
@@ -74,6 +76,7 @@
 struct sx8654 {
        struct input_dev *input;
        struct i2c_client *client;
+       struct gpio_desc *gpio_reset;
 };
 
 static irqreturn_t sx8654_irq(int irq, void *handle)
@@ -124,6 +127,25 @@ static irqreturn_t sx8654_irq(int irq, void *handle)
        return IRQ_HANDLED;
 }
 
+static int sx8654_reset(struct sx8654 *ts)
+{
+       int err;
+
+       if (ts->gpio_reset) {
+               gpiod_set_value_cansleep(ts->gpio_reset, 1);
+               udelay(2); /* Tpulse > 1µs */
+               gpiod_set_value_cansleep(ts->gpio_reset, 0);
+       } else {
+               dev_dbg(&ts->client->dev, "NRST unavailable, try softreset\n");
+               err = i2c_smbus_write_byte_data(ts->client, I2C_REG_SOFTRESET,
+                                               SOFTRESET_VALUE);
+               if (err)
+                       return err;
+       }
+
+       return 0;
+}
+
 static int sx8654_open(struct input_dev *dev)
 {
        struct sx8654 *sx8654 = input_get_drvdata(dev);
@@ -186,6 +208,17 @@ static int sx8654_probe(struct i2c_client *client,
        if (!sx8654)
                return -ENOMEM;
 
+       sx8654->gpio_reset = devm_gpiod_get_optional(&client->dev, "reset",
+                                                    GPIOD_OUT_HIGH);
+       if (IS_ERR(sx8654->gpio_reset)) {
+               error = PTR_ERR(sx8654->gpio_reset);
+               if (error != -EPROBE_DEFER)
+                       dev_err(&client->dev, "unable to get reset-gpio: %d\n",
+                               error);
+               return error;
+       }
+       dev_dbg(&client->dev, "got GPIO reset pin\n");
+
        input = devm_input_allocate_device(&client->dev);
        if (!input)
                return -ENOMEM;
@@ -206,10 +239,9 @@ static int sx8654_probe(struct i2c_client *client,
 
        input_set_drvdata(sx8654->input, sx8654);
 
-       error = i2c_smbus_write_byte_data(client, I2C_REG_SOFTRESET,
-                                         SOFTRESET_VALUE);
+       error = sx8654_reset(sx8654);
        if (error) {
-               dev_err(&client->dev, "writing softreset value failed");
+               dev_err(&client->dev, "reset failed");
                return error;
        }