Input: atmel_mxt_ts - add support for reset line

Provide support for controlling reset pin. If this is not driven
correctly the device will be held in reset and will not respond.

Acked-by: Rob Herring <[e-mail]>
Signed-off-by: Sebastian Reichel <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/atmel,maxtouch.txt

···
     experiment to determine which bit corresponds to which input. Use
     KEY_RESERVED for unused padding values.
 
+- reset-gpios: GPIO specifier for the touchscreen's reset pin (active low)
+
 Example:
 
 	touch@4b {

drivers/input/touchscreen/atmel_mxt_ts.c

···
 #include <linux/interrupt.h>
 #include <linux/of.h>
 #include <linux/slab.h>
+#include <linux/gpio/consumer.h>
 #include <asm/unaligned.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-ioctl.h>
···
 	u8 multitouch;
 	struct t7_config t7_cfg;
 	struct mxt_dbg dbg;
+	struct gpio_desc *reset_gpio;
 
 	/* Cached parameters from object table */
 	u16 T5_address;
···
 	init_completion(&data->reset_completion);
 	init_completion(&data->crc_completion);
 
+	data->reset_gpio = devm_gpiod_get_optional(&client->dev,
+						   "reset", GPIOD_OUT_LOW);
+	if (IS_ERR(data->reset_gpio)) {
+		error = PTR_ERR(data->reset_gpio);
+		dev_err(&client->dev, "Failed to get reset gpio: %d\n", error);
+		return error;
+	}
+
 	error = devm_request_threaded_irq(&client->dev, client->irq,
 					  NULL, mxt_interrupt,
 					  pdata->irqflags | IRQF_ONESHOT,
···
 	if (error) {
 		dev_err(&client->dev, "Failed to register interrupt\n");
 		return error;
+	}
+
+	if (data->reset_gpio) {
+		data->in_bootloader = true;
+		msleep(MXT_RESET_TIME);
+		reinit_completion(&data->bl_completion);
+		gpiod_set_value(data->reset_gpio, 1);
+		error = mxt_wait_for_completion(data, &data->bl_completion,
+						MXT_RESET_TIMEOUT);
+		if (error)
+			return error;
+		data->in_bootloader = false;
 	}
 
 	disable_irq(client->irq);