[PATCH v4 5/5] Input: msg2638 - Add support for msg2138 key events

[Vincent Knecht <vincent.knecht@xxxxxxxxxx>]

Some devices with msg2138 have back/menu/home keys.
Add support for them.

Signed-off-by: Vincent Knecht <vincent.knecht@xxxxxxxxxx>
---
 drivers/input/touchscreen/msg2638.c | 53 +++++++++++++++++++++++++----
 1 file changed, 47 insertions(+), 6 deletions(-)

diff --git a/drivers/input/touchscreen/msg2638.c b/drivers/input/touchscreen/msg2638.c
index 73e1b4d550fb..36069b30ab9b 100644
--- a/drivers/input/touchscreen/msg2638.c
+++ b/drivers/input/touchscreen/msg2638.c
@@ -29,6 +29,8 @@
 #define MSG2138_MAX_FINGERS		2
 #define MSG2638_MAX_FINGERS		5
 
+#define MAX_BUTTONS			4
+
 #define CHIP_ON_DELAY_MS		15
 #define FIRMWARE_ON_DELAY_MS		50
 #define RESET_DELAY_MIN_US		10000
@@ -72,6 +74,8 @@ struct msg2638_ts_data {
 	struct regulator_bulk_data supplies[2];
 	struct gpio_desc *reset_gpiod;
 	int max_fingers;
+	u32 keycodes[MAX_BUTTONS];
+	int num_keycodes;
 };
 
 static u8 msg2638_checksum(u8 *data, u32 length)
@@ -85,6 +89,19 @@ static u8 msg2638_checksum(u8 *data, u32 length)
 	return (u8)((-sum) & 0xFF);
 }
 
+static void msg2138_report_keys(struct msg2638_ts_data *msg2638, u8 keys)
+{
+	int i;
+
+	/* keys can be 0x00 or 0xff when all keys have been released */
+	if (keys == 0xff)
+		keys = 0;
+
+	for (i = 0; i < msg2638->num_keycodes; ++i)
+		input_report_key(msg2638->input_dev, msg2638->keycodes[i],
+				 !!(keys & BIT(i)));
+}
+
 static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
 {
 	struct msg2638_ts_data *msg2638 = msg2638_handler;
@@ -121,9 +138,12 @@ static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
 	p0 = &touch_event.pkt[0];
 	p1 = &touch_event.pkt[1];
 
-	/* Ignore non-pressed finger data */
-	if (p0->xy_hi == 0xFF && p0->x_low == 0xFF && p0->y_low == 0xFF)
+	/* Ignore non-pressed finger data, but check for key code */
+	if (p0->xy_hi == 0xFF && p0->x_low == 0xFF && p0->y_low == 0xFF) {
+		if (p1->xy_hi == 0xFF && p1->y_low == 0xFF)
+			msg2138_report_keys(msg2638, p1->x_low);
 		goto report;
+	}
 
 	x = (((p0->xy_hi & 0xF0) << 4) | p0->x_low);
 	y = (((p0->xy_hi & 0x0F) << 8) | p0->y_low);
@@ -283,6 +303,7 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
 	struct device *dev = &msg2638->client->dev;
 	struct input_dev *input_dev;
 	int error;
+	int i;
 
 	input_dev = devm_input_allocate_device(dev);
 	if (!input_dev) {
@@ -299,6 +320,14 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
 	input_dev->open = msg2638_input_open;
 	input_dev->close = msg2638_input_close;
 
+	if (msg2638->num_keycodes) {
+		input_dev->keycode = msg2638->keycodes;
+		input_dev->keycodemax = msg2638->num_keycodes;
+		input_dev->keycodesize = sizeof(msg2638->keycodes[0]);
+		for (i = 0; i < msg2638->num_keycodes; i++)
+			input_set_capability(input_dev, EV_KEY, msg2638->keycodes[i]);
+	}
+
 	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
 	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
 
@@ -367,10 +396,16 @@ static int msg2638_ts_probe(struct i2c_client *client)
 		return error;
 	}
 
-	error = msg2638_init_input_dev(msg2638);
-	if (error) {
-		dev_err(dev, "Failed to initialize input device: %d\n", error);
-		return error;
+	msg2638->num_keycodes =
+		of_property_read_variable_u32_array(dev->of_node, "linux,keycodes",
+						    msg2638->keycodes, 0,
+						    ARRAY_SIZE(msg2638->keycodes));
+	if (msg2638->num_keycodes == -EINVAL) {
+		msg2638->num_keycodes = 0;
+	} else if (msg2638->num_keycodes < 0) {
+		dev_err(dev, "Unable to parse linux,keycodes property: %d\n",
+			msg2638->num_keycodes);
+		return msg2638->num_keycodes;
 	}
 
 	error = devm_request_threaded_irq(dev, client->irq,
@@ -382,6 +417,12 @@ static int msg2638_ts_probe(struct i2c_client *client)
 		return error;
 	}
 
+	error = msg2638_init_input_dev(msg2638);
+	if (error) {
+		dev_err(dev, "Failed to initialize input device: %d\n", error);
+		return error;
+	}
+
 	return 0;
 }
 
-- 
2.38.1