Input: imagis - add touch key support

IST3032C (and possibly some other models) has touch keys. Add support
for them to the imagis driver.

Signed-off-by: Duje Mihanović <duje.mihanovic@skole.hr>
Link: https://lore.kernel.org/r/20240306-b4-imagis-keys-v3-3-2c429afa8420@skole.hr
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: LegoLivesMatter

drivers/input/touchscreen/imagis.c

@@ -34,13 +34,15 @@
 #define IST3038C_AREA_MASK		GENMASK(27, 24)
 #define IST3038C_FINGER_COUNT_MASK	GENMASK(15, 12)
 #define IST3038C_FINGER_STATUS_MASK	GENMASK(9, 0)
+#define IST3032C_KEY_STATUS_MASK	GENMASK(20, 16)
 
 struct imagis_properties {
 	unsigned int interrupt_msg_cmd;
 	unsigned int touch_coord_cmd;
 	unsigned int whoami_cmd;
 	unsigned int whoami_val;
 	bool protocol_b;
+	bool touch_keys_supported;
 };
 
 struct imagis_ts {
@@ -49,6 +51,8 @@ struct imagis_ts {
 	struct input_dev *input_dev;
 	struct touchscreen_properties prop;
 	struct regulator_bulk_data supplies[2];
+	u32 keycodes[5];
+	int num_keycodes;
 };
 
 static int imagis_i2c_read_reg(struct imagis_ts *ts,
@@ -93,7 +97,7 @@ static irqreturn_t imagis_interrupt(int irq, void *dev_id)
 {
 	struct imagis_ts *ts = dev_id;
 	u32 intr_message, finger_status;
-	unsigned int finger_count, finger_pressed;
+	unsigned int finger_count, finger_pressed, key_pressed;
 	int i;
 	int error;
 
@@ -140,6 +144,12 @@ static irqreturn_t imagis_interrupt(int irq, void *dev_id)
 				 FIELD_GET(IST3038C_AREA_MASK, finger_status));
 	}
 
+	key_pressed = FIELD_GET(IST3032C_KEY_STATUS_MASK, intr_message);
+
+	for (int i = 0; i < ts->num_keycodes; i++)
+		input_report_key(ts->input_dev, ts->keycodes[i],
+				 key_pressed & BIT(i));
+
 	input_mt_sync_frame(ts->input_dev);
 	input_sync(ts->input_dev);
 
@@ -225,6 +235,23 @@ static int imagis_init_input_dev(struct imagis_ts *ts)
 	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_X);
 	input_set_capability(input_dev, EV_ABS, ABS_MT_POSITION_Y);
 	input_set_abs_params(input_dev, ABS_MT_TOUCH_MAJOR, 0, 16, 0, 0);
+	if (ts->tdata->touch_keys_supported) {
+		ts->num_keycodes = of_property_read_variable_u32_array(
+				ts->client->dev.of_node, "linux,keycodes",
+				ts->keycodes, 0, ARRAY_SIZE(ts->keycodes));
+		if (ts->num_keycodes <= 0) {
+			ts->keycodes[0] = KEY_APPSELECT;
+			ts->keycodes[1] = KEY_BACK;
+			ts->num_keycodes = 2;
+		}
+
+		input_dev->keycodemax = ts->num_keycodes;
+		input_dev->keycodesize = sizeof(ts->keycodes[0]);
+		input_dev->keycode = ts->keycodes;
+	}
+
+	for (int i = 0; i < ts->num_keycodes; i++)
+		input_set_capability(input_dev, EV_KEY, ts->keycodes[i]);
 
 	touchscreen_parse_properties(input_dev, true, &ts->prop);
 	if (!ts->prop.max_x || !ts->prop.max_y) {
@@ -366,6 +393,7 @@ static const struct imagis_properties imagis_3032c_data = {
 	.touch_coord_cmd = IST3038C_REG_TOUCH_COORD,
 	.whoami_cmd = IST3038C_REG_CHIPID,
 	.whoami_val = IST3032C_WHOAMI,
+	.touch_keys_supported = true,
 };
 
 static const struct imagis_properties imagis_3038b_data = {