Input: goodix - add support for more then one touch-key

Some devices with a goodix touchscreen have more then 1 capacitive
touch-key. This commit replaces the current support for a single
touch-key, which ignored the reported key-code. With support for
up to 7 touch-keys, based upon checking the key-code which is
post-fixed to any reported touch-data.

KEY_LEFTMETA is assigned to the first touch-key (it will still be
the default keycode for devices with a single touch-key).
KEY_F1, KEY_F2... are assigned as default keycode for the other
touch-keys.

This commit also add supports for keycode remapping, so that
systemd-udev's hwdb can be used to remap the codes to send
keycodes to match the icons on the buttons for devices with more
then 1 touch-key.
Signed-off-by: Dmitry Mastykin <dmastykin@astralinux.ru>
Reviewed-by: Bastien Nocera <hadess@hadess.net>
Link: https://lore.kernel.org/r/20200316075302.3759-1-dmastykin@astralinux.ruSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/goodix.c

@@ -38,6 +38,7 @@
 #define GOODIX_CONTACT_SIZE		8
 #define GOODIX_MAX_CONTACT_SIZE		9
 #define GOODIX_MAX_CONTACTS		10
+#define GOODIX_MAX_KEYS			7
 
 #define GOODIX_CONFIG_MIN_LENGTH	186
 #define GOODIX_CONFIG_911_LENGTH	186
@@ -55,6 +56,7 @@
 #define GOODIX_REG_ID			0x8140
 
 #define GOODIX_BUFFER_STATUS_READY	BIT(7)
+#define GOODIX_HAVE_KEY			BIT(4)
 #define GOODIX_BUFFER_STATUS_TIMEOUT	20
 
 #define RESOLUTION_LOC		1
@@ -100,6 +102,7 @@ struct goodix_ts_data {
 	enum goodix_irq_pin_access_method irq_pin_access_method;
 	unsigned int contact_size;
 	u8 config[GOODIX_CONFIG_MAX_LENGTH];
+	unsigned short keymap[GOODIX_MAX_KEYS];
 };
 
 static int goodix_check_cfg_8(struct goodix_ts_data *ts,
@@ -302,6 +305,13 @@ static int goodix_ts_read_input_report(struct goodix_ts_data *ts, u8 *data)
 	unsigned long max_timeout;
 	int touch_num;
 	int error;
+	u16 addr = GOODIX_READ_COOR_ADDR;
+	/*
+	 * We are going to read 1-byte header,
+	 * ts->contact_size * max(1, touch_num) bytes of coordinates
+	 * and 1-byte footer which contains the touch-key code.
+	 */
+	const int header_contact_keycode_size = 1 + ts->contact_size + 1;
 
 	/*
 	 * The 'buffer status' bit, which indicates that the data is valid, is
@@ -310,8 +320,8 @@ static int goodix_ts_read_input_report(struct goodix_ts_data *ts, u8 *data)
 	 */
 	max_timeout = jiffies + msecs_to_jiffies(GOODIX_BUFFER_STATUS_TIMEOUT);
 	do {
-		error = goodix_i2c_read(ts->client, GOODIX_READ_COOR_ADDR,
-					data, ts->contact_size + 1);
+		error = goodix_i2c_read(ts->client, addr, data,
+					header_contact_keycode_size);
 		if (error) {
 			dev_err(&ts->client->dev, "I2C transfer error: %d\n",
 					error);
@@ -324,11 +334,10 @@ static int goodix_ts_read_input_report(struct goodix_ts_data *ts, u8 *data)
 				return -EPROTO;
 
 			if (touch_num > 1) {
-				data += 1 + ts->contact_size;
+				addr += header_contact_keycode_size;
+				data += header_contact_keycode_size;
 				error = goodix_i2c_read(ts->client,
-						GOODIX_READ_COOR_ADDR +
-							1 + ts->contact_size,
-						data,
+						addr, data,
 						ts->contact_size *
 							(touch_num - 1));
 				if (error)
@@ -378,6 +387,25 @@ static void goodix_ts_report_touch_9b(struct goodix_ts_data *ts, u8 *coor_data)
 	input_report_abs(ts->input_dev, ABS_MT_WIDTH_MAJOR, input_w);
 }
 
+static void goodix_ts_report_key(struct goodix_ts_data *ts, u8 *data)
+{
+	int touch_num;
+	u8 key_value;
+	int i;
+
+	if (data[0] & GOODIX_HAVE_KEY) {
+		touch_num = data[0] & 0x0f;
+		key_value = data[1 + ts->contact_size * touch_num];
+		for (i = 0; i < GOODIX_MAX_KEYS; i++)
+			if (key_value & BIT(i))
+				input_report_key(ts->input_dev,
+						 ts->keymap[i], 1);
+	} else {
+		for (i = 0; i < GOODIX_MAX_KEYS; i++)
+			input_report_key(ts->input_dev, ts->keymap[i], 0);
+	}
+}
+
 /**
  * goodix_process_events - Process incoming events
  *
@@ -388,7 +416,7 @@ static void goodix_ts_report_touch_9b(struct goodix_ts_data *ts, u8 *coor_data)
  */
 static void goodix_process_events(struct goodix_ts_data *ts)
 {
-	u8  point_data[1 + GOODIX_MAX_CONTACT_SIZE * GOODIX_MAX_CONTACTS];
+	u8  point_data[2 + GOODIX_MAX_CONTACT_SIZE * GOODIX_MAX_CONTACTS];
 	int touch_num;
 	int i;
 
@@ -396,11 +424,7 @@ static void goodix_process_events(struct goodix_ts_data *ts)
 	if (touch_num < 0)
 		return;
 
-	/*
-	 * Bit 4 of the first byte reports the status of the capacitive
-	 * Windows/Home button.
-	 */
-	input_report_key(ts->input_dev, KEY_LEFTMETA, point_data[0] & BIT(4));
+	goodix_ts_report_key(ts, point_data);
 
 	for (i = 0; i < touch_num; i++)
 		if (ts->contact_size == 9)
@@ -986,6 +1010,7 @@ static int goodix_i2c_test(struct i2c_client *client)
 static int goodix_configure_dev(struct goodix_ts_data *ts)
 {
 	int error;
+	int i;
 
 	ts->int_trigger_type = GOODIX_INT_TRIGGER;
 	ts->max_touch_num = GOODIX_MAX_CONTACTS;
@@ -1003,8 +1028,19 @@ static int goodix_configure_dev(struct goodix_ts_data *ts)
 	ts->input_dev->id.product = ts->id;
 	ts->input_dev->id.version = ts->version;
 
+	ts->input_dev->keycode = ts->keymap;
+	ts->input_dev->keycodesize = sizeof(ts->keymap[0]);
+	ts->input_dev->keycodemax = GOODIX_MAX_KEYS;
+
 	/* Capacitive Windows/Home button on some devices */
-	input_set_capability(ts->input_dev, EV_KEY, KEY_LEFTMETA);
+	for (i = 0; i < GOODIX_MAX_KEYS; ++i) {
+		if (i == 0)
+			ts->keymap[i] = KEY_LEFTMETA;
+		else
+			ts->keymap[i] = KEY_F1 + (i - 1);
+
+		input_set_capability(ts->input_dev, EV_KEY, ts->keymap[i]);
+	}
 
 	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_X);
 	input_set_capability(ts->input_dev, EV_ABS, ABS_MT_POSITION_Y);