Input: edt-ft5x06 - add support for regulator

Add the support for enabling optional regulator that may be used as VCC
source.

Signed-off-by: Mylène Josserand <[e-mail]>
Signed-off-by: Ondrej Jirman <[e-mail]>
Reviewed-by: Rob Herring <[e-mail]> # bindings
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Dmitry Torokhov <[e-mail]>

Documentation/devicetree/bindings/input/touchscreen/edt-ft5x06.txt

···
 Optional properties:
  - reset-gpios: GPIO specification for the RESET input
  - wake-gpios:  GPIO specification for the WAKE input
+ - vcc-supply:  Regulator that supplies the touchscreen
 
  - pinctrl-names: should be "default"
  - pinctrl-0:   a phandle pointing to the pin settings for the

drivers/input/touchscreen/edt-ft5x06.c

···
 #include <linux/input/mt.h>
 #include <linux/input/touchscreen.h>
 #include <asm/unaligned.h>
+#include <linux/regulator/consumer.h>
 
 #define WORK_REGISTER_THRESHOLD		0x00
 #define WORK_REGISTER_REPORT_RATE	0x08
···
 	struct touchscreen_properties prop;
 	u16 num_x;
 	u16 num_y;
+	struct regulator *vcc;
 
 	struct gpio_desc *reset_gpio;
 	struct gpio_desc *wake_gpio;
···
 	}
 }
 
+static void edt_ft5x06_disable_regulator(void *arg)
+{
+	struct edt_ft5x06_ts_data *data = arg;
+
+	regulator_disable(data->vcc);
+}
+
 static int edt_ft5x06_ts_probe(struct i2c_client *client,
 					 const struct i2c_device_id *id)
 {
···
 	}
 
 	tsdata->max_support_points = chip_data->max_support_points;
+
+	tsdata->vcc = devm_regulator_get(&client->dev, "vcc");
+	if (IS_ERR(tsdata->vcc)) {
+		error = PTR_ERR(tsdata->vcc);
+		if (error != -EPROBE_DEFER)
+			dev_err(&client->dev,
+				"failed to request regulator: %d\n", error);
+		return error;
+	}
+
+	error = regulator_enable(tsdata->vcc);
+	if (error < 0) {
+		dev_err(&client->dev, "failed to enable vcc: %d\n", error);
+		return error;
+	}
+
+	error = devm_add_action_or_reset(&client->dev,
+					 edt_ft5x06_disable_regulator,
+					 tsdata);
+	if (error)
+		return error;
 
 	tsdata->reset_gpio = devm_gpiod_get_optional(&client->dev,
 						     "reset", GPIOD_OUT_HIGH);