Input: zinitix - add touchkey support

Zinitix touch controllers can use some of the sense lines for virtual
keys (like those found on many phones). Add support for those keys.

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Nikita Travkin <nikita@trvn.ru>
Link: https://lore.kernel.org/r/20240717-zinitix-tkey-v5-2-52ea4cd4bd50@trvn.ru
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/zinitix.c

@@ -10,6 +10,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/property.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 
@@ -119,6 +120,7 @@
 
 #define DEFAULT_TOUCH_POINT_MODE		2
 #define MAX_SUPPORTED_FINGER_NUM		5
+#define MAX_SUPPORTED_BUTTON_NUM		8
 
 #define CHIP_ON_DELAY				15 // ms
 #define FIRMWARE_ON_DELAY			40 // ms
@@ -146,6 +148,8 @@ struct bt541_ts_data {
 	struct touchscreen_properties prop;
 	struct regulator_bulk_data supplies[2];
 	u32 zinitix_mode;
+	u32 keycodes[MAX_SUPPORTED_BUTTON_NUM];
+	int num_keycodes;
 };
 
 static int zinitix_read_data(struct i2c_client *client,
@@ -195,6 +199,7 @@ static int zinitix_init_touch(struct bt541_ts_data *bt541)
 	struct i2c_client *client = bt541->client;
 	int i;
 	int error;
+	u16 int_flags;
 
 	error = zinitix_write_cmd(client, ZINITIX_SWRESET_CMD);
 	if (error) {
@@ -225,6 +230,11 @@ static int zinitix_init_touch(struct bt541_ts_data *bt541)
 	if (error)
 		return error;
 
+	error = zinitix_write_u16(client, ZINITIX_BUTTON_SUPPORTED_NUM,
+				  bt541->num_keycodes);
+	if (error)
+		return error;
+
 	error = zinitix_write_u16(client, ZINITIX_INITIAL_TOUCH_MODE,
 				  bt541->zinitix_mode);
 	if (error)
@@ -235,9 +245,11 @@ static int zinitix_init_touch(struct bt541_ts_data *bt541)
 	if (error)
 		return error;
 
-	error = zinitix_write_u16(client, ZINITIX_INT_ENABLE_FLAG,
-				  BIT_PT_CNT_CHANGE | BIT_DOWN | BIT_MOVE |
-					BIT_UP);
+	int_flags = BIT_PT_CNT_CHANGE | BIT_DOWN | BIT_MOVE | BIT_UP;
+	if (bt541->num_keycodes)
+		int_flags |= BIT_ICON_EVENT;
+
+	error = zinitix_write_u16(client, ZINITIX_INT_ENABLE_FLAG, int_flags);
 	if (error)
 		return error;
 
@@ -350,12 +362,22 @@ static void zinitix_report_finger(struct bt541_ts_data *bt541, int slot,
 	}
 }
 
+static void zinitix_report_keys(struct bt541_ts_data *bt541, u16 icon_events)
+{
+	int i;
+
+	for (i = 0; i < bt541->num_keycodes; i++)
+		input_report_key(bt541->input_dev,
+				 bt541->keycodes[i], icon_events & BIT(i));
+}
+
 static irqreturn_t zinitix_ts_irq_handler(int irq, void *bt541_handler)
 {
 	struct bt541_ts_data *bt541 = bt541_handler;
 	struct i2c_client *client = bt541->client;
 	struct touch_event touch_event;
 	unsigned long finger_mask;
+	__le16 icon_events;
 	int error;
 	int i;
 
@@ -368,6 +390,17 @@ static irqreturn_t zinitix_ts_irq_handler(int irq, void *bt541_handler)
 		goto out;
 	}
 
+	if (le16_to_cpu(touch_event.status) & BIT_ICON_EVENT) {
+		error = zinitix_read_data(bt541->client, ZINITIX_ICON_STATUS_REG,
+					  &icon_events, sizeof(icon_events));
+		if (error) {
+			dev_err(&client->dev, "Failed to read icon events\n");
+			goto out;
+		}
+
+		zinitix_report_keys(bt541, le16_to_cpu(icon_events));
+	}
+
 	finger_mask = touch_event.finger_mask;
 	for_each_set_bit(i, &finger_mask, MAX_SUPPORTED_FINGER_NUM) {
 		const struct point_coord *p = &touch_event.point_coord[i];
@@ -453,6 +486,7 @@ static int zinitix_init_input_dev(struct bt541_ts_data *bt541)
 {
 	struct input_dev *input_dev;
 	int error;
+	int i;
 
 	input_dev = devm_input_allocate_device(&bt541->client->dev);
 	if (!input_dev) {
@@ -470,6 +504,14 @@ static int zinitix_init_input_dev(struct bt541_ts_data *bt541)
 	input_dev->open = zinitix_input_open;
 	input_dev->close = zinitix_input_close;
 
+	if (bt541->num_keycodes) {
+		input_dev->keycode = bt541->keycodes;
+		input_dev->keycodemax = bt541->num_keycodes;
+		input_dev->keycodesize = sizeof(bt541->keycodes[0]);
+		for (i = 0; i < bt541->num_keycodes; i++)
+			input_set_capability(input_dev, EV_KEY, bt541->keycodes[i]);
+	}
+
 	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_WIDTH_MAJOR, 0, 255, 0, 0);
@@ -534,6 +576,21 @@ static int zinitix_ts_probe(struct i2c_client *client)
 		return error;
 	}
 
+	bt541->num_keycodes = device_property_count_u32(&client->dev, "linux,keycodes");
+	if (bt541->num_keycodes > ARRAY_SIZE(bt541->keycodes)) {
+		dev_err(&client->dev, "too many keys defined (%d)\n", bt541->num_keycodes);
+		return -EINVAL;
+	}
+
+	error = device_property_read_u32_array(&client->dev, "linux,keycodes",
+					       bt541->keycodes,
+					       bt541->num_keycodes);
+	if (error) {
+		dev_err(&client->dev,
+			"Unable to parse \"linux,keycodes\" property: %d\n", error);
+		return error;
+	}
+
 	error = zinitix_init_input_dev(bt541);
 	if (error) {
 		dev_err(&client->dev,