Input: tm2-touchkey - add vddio regulator

The Samsung touchkey controllers are often used with external pull-up
for the interrupt line and the I2C lines, so we might need to enable
a regulator to bring the lines into usable state. Otherwise, this might
cause spurious interrupts and reading from I2C will fail.

Implement support for a "vddio-supply" that is enabled by the
tm2-touchkey driver so that the regulator gets enabled when needed.
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201203131242.44397-3-stephan@gerhold.netSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/tm2-touchkey.c

@@ -48,7 +48,7 @@ struct tm2_touchkey_data {
 	struct input_dev *input_dev;
 	struct led_classdev led_dev;
 	struct regulator *vdd;
-	struct regulator_bulk_data regulators[2];
+	struct regulator_bulk_data regulators[3];
 	const struct touchkey_variant *variant;
 	u32 keycodes[4];
 	int num_keycodes;
@@ -204,6 +204,7 @@ static int tm2_touchkey_probe(struct i2c_client *client,
 
 	touchkey->regulators[0].supply = "vcc";
 	touchkey->regulators[1].supply = "vdd";
+	touchkey->regulators[2].supply = "vddio";
 	error = devm_regulator_bulk_get(&client->dev,
 					ARRAY_SIZE(touchkey->regulators),
 					touchkey->regulators);