Input: tm2-touchkey - add support for aries touchkey variant

The touchkey variant found on aries board is slighty different,
it uses a fixed regulator and writes/read to the same place
Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Documentation/devicetree/bindings/input/cypress,tm2-touchkey.txt

@@ -4,6 +4,7 @@ Required properties:
 - compatible:
     * "cypress,tm2-touchkey" - for the touchkey found on the tm2 board
     * "cypress,midas-touchkey" - for the touchkey found on midas boards
+    * "cypress,aries-touchkey" - for the touchkey found on aries boards
 - reg: I2C address of the chip.
 - interrupt-parent: a phandle for the interrupt controller (see interrupt
 	binding[0]).

drivers/input/keyboard/tm2-touchkey.c

@@ -28,6 +28,8 @@
 
 #define TM2_TOUCHKEY_DEV_NAME		"tm2-touchkey"
 
+#define ARIES_TOUCHKEY_CMD_LED_ON	0x1
+#define ARIES_TOUCHKEY_CMD_LED_OFF	0x2
 #define TM2_TOUCHKEY_CMD_LED_ON		0x10
 #define TM2_TOUCHKEY_CMD_LED_OFF	0x20
 #define TM2_TOUCHKEY_BIT_PRESS_EV	BIT(3)
@@ -38,6 +40,10 @@
 struct touchkey_variant {
 	u8 keycode_reg;
 	u8 base_reg;
+	u8 cmd_led_on;
+	u8 cmd_led_off;
+	bool no_reg;
+	bool fixed_regulator;
 };
 
 struct tm2_touchkey_data {
@@ -54,11 +60,22 @@ struct tm2_touchkey_data {
 static const struct touchkey_variant tm2_touchkey_variant = {
 	.keycode_reg = 0x03,
 	.base_reg = 0x00,
+	.cmd_led_on = TM2_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = TM2_TOUCHKEY_CMD_LED_OFF,
 };
 
 static const struct touchkey_variant midas_touchkey_variant = {
 	.keycode_reg = 0x00,
 	.base_reg = 0x00,
+	.cmd_led_on = TM2_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = TM2_TOUCHKEY_CMD_LED_OFF,
+};
+
+static struct touchkey_variant aries_touchkey_variant = {
+	.no_reg = true,
+	.fixed_regulator = true,
+	.cmd_led_on = ARIES_TOUCHKEY_CMD_LED_ON,
+	.cmd_led_off = ARIES_TOUCHKEY_CMD_LED_OFF,
 };
 
 static void tm2_touchkey_led_brightness_set(struct led_classdev *led_dev,
@@ -71,13 +88,18 @@ static void tm2_touchkey_led_brightness_set(struct led_classdev *led_dev,
 
 	if (brightness == LED_OFF) {
 		volt = TM2_TOUCHKEY_LED_VOLTAGE_MIN;
-		data = TM2_TOUCHKEY_CMD_LED_OFF;
+		data = touchkey->variant->cmd_led_off;
 	} else {
 		volt = TM2_TOUCHKEY_LED_VOLTAGE_MAX;
-		data = TM2_TOUCHKEY_CMD_LED_ON;
+		data = touchkey->variant->cmd_led_on;
 	}
 
+	if (!touchkey->variant->fixed_regulator)
 		regulator_set_voltage(touchkey->vdd, volt, volt);
+
+	if (touchkey->variant->no_reg)
+		i2c_smbus_write_byte(touchkey->client, data);
+	else
 		i2c_smbus_write_byte_data(touchkey->client,
 					  touchkey->variant->base_reg, data);
 }
@@ -112,6 +134,9 @@ static irqreturn_t tm2_touchkey_irq_handler(int irq, void *devid)
 	int index;
 	int i;
 
+	if (touchkey->variant->no_reg)
+		data = i2c_smbus_read_byte(touchkey->client);
+	else
 		data = i2c_smbus_read_byte_data(touchkey->client,
 						touchkey->variant->keycode_reg);
 	if (data < 0) {
@@ -139,6 +164,14 @@ static irqreturn_t tm2_touchkey_irq_handler(int irq, void *devid)
 	input_sync(touchkey->input_dev);
 
 out:
+	if (touchkey->variant->fixed_regulator &&
+				data & TM2_TOUCHKEY_BIT_PRESS_EV) {
+		/* touch turns backlight on, so make sure we're in sync */
+		if (touchkey->led_dev.brightness == LED_OFF)
+			tm2_touchkey_led_brightness_set(&touchkey->led_dev,
+							LED_OFF);
+	}
+
 	return IRQ_HANDLED;
 }
 
@@ -246,6 +279,9 @@ static int tm2_touchkey_probe(struct i2c_client *client,
 		return error;
 	}
 
+	if (touchkey->variant->fixed_regulator)
+		tm2_touchkey_led_brightness_set(&touchkey->led_dev, LED_ON);
+
 	return 0;
 }
 
@@ -291,6 +327,9 @@ static const struct of_device_id tm2_touchkey_of_match[] = {
 	}, {
 		.compatible = "cypress,midas-touchkey",
 		.data = &midas_touchkey_variant,
+	}, {
+		.compatible = "cypress,aries-touchkey",
+		.data = &aries_touchkey_variant,
 	},
 	{ },
 };