[PATCH 0/5] msg2638: Add support for msg2138 and key events

[PATCH 0/5] msg2638: Add support for msg2138 and key events

[Vincent Knecht]

This series:
- moves max fingers number and irqhandler settings in a struct
- adds support for msg2138 touchscreen
- adds support for buttons, which were only seen with msg2138 as of yet

Big thanks to Stephan Gerhold <stephan@gerhold.net> for the help with
deciphering the downstream driver [1] and writing clean and working code.

[1] https://github.com/LineageOS/android_kernel_huawei_msm8916/blob/2f24fa58086a969687434b40f237cb589a1f324f/drivers/input/touchscreen/mstar/msg2138_qc.c

Vincent Knecht (5):
  Input: msg2638 - Set max finger number and irqhandler from driver data
  dt-bindings: input: touchscreen: msg2638: Document msg2138 support
  Input: msg2638 - Add support for msg2138
  dt-bindings: input: touchscreen: msg2638: Document keys support
  Input: msg2638 - Add support for msg2138 key events

 .../input/touchscreen/mstar,msg2638.yaml      |   8 +-
 drivers/input/touchscreen/msg2638.c           | 182 ++++++++++++++++--
 2 files changed, 175 insertions(+), 15 deletions(-)

-- 
2.31.1

[PATCH 1/5] Input: msg2638 - Set max finger number and irqhandler from driver data

[Vincent Knecht]

This will allow us to add other MStar touchscreen variants' support.
No functional change.

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
---
 drivers/input/touchscreen/msg2638.c | 40 +++++++++++++++++++++--------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/input/touchscreen/msg2638.c b/drivers/input/touchscreen/msg2638.c
index 75536bc88969..222adedf78bf 100644
--- a/drivers/input/touchscreen/msg2638.c
+++ b/drivers/input/touchscreen/msg2638.c
@@ -26,23 +26,28 @@
 
 #define MODE_DATA_RAW			0x5A
 
-#define MAX_SUPPORTED_FINGER_NUM	5
+#define MSG2638_MAX_FINGERS		5
 
 #define CHIP_ON_DELAY_MS		15
 #define FIRMWARE_ON_DELAY_MS		50
 #define RESET_DELAY_MIN_US		10000
 #define RESET_DELAY_MAX_US		11000
 
-struct packet {
+struct msg_chip_data {
+	irq_handler_t irq_handler;
+	unsigned int max_fingers;
+};
+
+struct msg2638_packet {
 	u8	xy_hi; /* higher bits of x and y coordinates */
 	u8	x_low;
 	u8	y_low;
 	u8	pressure;
 };
 
-struct touch_event {
+struct msg2638_touch_event {
 	u8	mode;
-	struct	packet pkt[MAX_SUPPORTED_FINGER_NUM];
+	struct	msg2638_packet pkt[MSG2638_MAX_FINGERS];
 	u8	proximity;
 	u8	checksum;
 };
@@ -53,6 +58,7 @@ struct msg2638_ts_data {
 	struct touchscreen_properties prop;
 	struct regulator_bulk_data supplies[2];
 	struct gpio_desc *reset_gpiod;
+	int max_fingers;
 };
 
 static u8 msg2638_checksum(u8 *data, u32 length)
@@ -71,7 +77,7 @@ static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
 	struct msg2638_ts_data *msg2638 = msg2638_handler;
 	struct i2c_client *client = msg2638->client;
 	struct input_dev *input = msg2638->input_dev;
-	struct touch_event touch_event;
+	struct msg2638_touch_event touch_event;
 	u32 len = sizeof(touch_event);
 	struct i2c_msg msg[] = {
 		{
@@ -81,7 +87,7 @@ static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
 			.buf	= (u8 *)&touch_event,
 		},
 	};
-	struct packet *p;
+	struct msg2638_packet *p;
 	u16 x, y;
 	int ret;
 	int i;
@@ -103,7 +109,7 @@ static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
 		goto out;
 	}
 
-	for (i = 0; i < MAX_SUPPORTED_FINGER_NUM; i++) {
+	for (i = 0; i < msg2638->max_fingers; i++) {
 		p = &touch_event.pkt[i];
 
 		/* Ignore non-pressed finger data */
@@ -215,7 +221,7 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
 		return -EINVAL;
 	}
 
-	error = input_mt_init_slots(input_dev, MAX_SUPPORTED_FINGER_NUM,
+	error = input_mt_init_slots(input_dev, msg2638->max_fingers,
 				    INPUT_MT_DIRECT | INPUT_MT_DROP_UNUSED);
 	if (error) {
 		dev_err(dev, "Failed to initialize MT slots: %d\n", error);
@@ -233,6 +239,7 @@ static int msg2638_init_input_dev(struct msg2638_ts_data *msg2638)
 
 static int msg2638_ts_probe(struct i2c_client *client)
 {
+	const struct msg_chip_data *chip_data;
 	struct device *dev = &client->dev;
 	struct msg2638_ts_data *msg2638;
 	int error;
@@ -249,6 +256,14 @@ static int msg2638_ts_probe(struct i2c_client *client)
 	msg2638->client = client;
 	i2c_set_clientdata(client, msg2638);
 
+	chip_data = device_get_match_data(&client->dev);
+	if (!chip_data || !chip_data->max_fingers) {
+		dev_err(dev, "Invalid or missing chip data\n");
+		return -EINVAL;
+	}
+
+	msg2638->max_fingers = chip_data->max_fingers;
+
 	msg2638->supplies[0].supply = "vdd";
 	msg2638->supplies[1].supply = "vddio";
 	error = devm_regulator_bulk_get(dev, ARRAY_SIZE(msg2638->supplies),
@@ -272,7 +287,7 @@ static int msg2638_ts_probe(struct i2c_client *client)
 	}
 
 	error = devm_request_threaded_irq(dev, client->irq,
-					  NULL, msg2638_ts_irq_handler,
+					  NULL, chip_data->irq_handler,
 					  IRQF_ONESHOT | IRQF_NO_AUTOEN,
 					  client->name, msg2638);
 	if (error) {
@@ -316,8 +331,13 @@ static int __maybe_unused msg2638_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(msg2638_pm_ops, msg2638_suspend, msg2638_resume);
 
+static const struct msg_chip_data msg2638_data = {
+	.irq_handler = msg2638_ts_irq_handler,
+	.max_fingers = MSG2638_MAX_FINGERS,
+};
+
 static const struct of_device_id msg2638_of_match[] = {
-	{ .compatible = "mstar,msg2638" },
+	{ .compatible = "mstar,msg2638", .data = &msg2638_data },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, msg2638_of_match);
-- 
2.31.1

[PATCH 2/5] dt-bindings: input: touchscreen: msg2638: Document msg2138 support

[Vincent Knecht]

Document msg2138 support by adding mstar,msg2138 compatible.

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
---
 .../devicetree/bindings/input/touchscreen/mstar,msg2638.yaml  | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
index 3a42c23faf6f..2fb7e01bb65a 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
@@ -14,7 +14,9 @@ allOf:
 
 properties:
   compatible:
-    const: mstar,msg2638
+    enum:
+      - mstar,msg2138
+      - mstar,msg2638
 
   reg:
     const: 0x26
-- 
2.31.1

[PATCH 3/5] Input: msg2638 - Add support for msg2138

[Vincent Knecht]

msg2138 only supports 2 fingers presses, and needs different processing
since second finger press is encoded as a delta position wrt. first one
and the packet/touch_event structs are not the same as msg2638.

Add support for it by implementing distinct structs and irq handler.

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
---
 drivers/input/touchscreen/msg2638.c | 93 +++++++++++++++++++++++++++++
 1 file changed, 93 insertions(+)

diff --git a/drivers/input/touchscreen/msg2638.c b/drivers/input/touchscreen/msg2638.c
index 222adedf78bf..73e1b4d550fb 100644
--- a/drivers/input/touchscreen/msg2638.c
+++ b/drivers/input/touchscreen/msg2638.c
@@ -26,6 +26,7 @@
 
 #define MODE_DATA_RAW			0x5A
 
+#define MSG2138_MAX_FINGERS		2
 #define MSG2638_MAX_FINGERS		5
 
 #define CHIP_ON_DELAY_MS		15
@@ -38,6 +39,18 @@ struct msg_chip_data {
 	unsigned int max_fingers;
 };
 
+struct msg2138_packet {
+	u8	xy_hi; /* higher bits of x and y coordinates */
+	u8	x_low;
+	u8	y_low;
+};
+
+struct msg2138_touch_event {
+	u8	magic;
+	struct	msg2138_packet pkt[MSG2138_MAX_FINGERS];
+	u8	checksum;
+};
+
 struct msg2638_packet {
 	u8	xy_hi; /* higher bits of x and y coordinates */
 	u8	x_low;
@@ -72,6 +85,80 @@ static u8 msg2638_checksum(u8 *data, u32 length)
 	return (u8)((-sum) & 0xFF);
 }
 
+static irqreturn_t msg2138_ts_irq_handler(int irq, void *msg2638_handler)
+{
+	struct msg2638_ts_data *msg2638 = msg2638_handler;
+	struct i2c_client *client = msg2638->client;
+	struct input_dev *input = msg2638->input_dev;
+	struct msg2138_touch_event touch_event;
+	u32 len = sizeof(touch_event);
+	struct i2c_msg msg[] = {
+		{
+			.addr	= client->addr,
+			.flags	= I2C_M_RD,
+			.len	= sizeof(touch_event),
+			.buf	= (u8 *)&touch_event,
+		},
+	};
+	struct msg2138_packet *p0, *p1;
+	u16 x, y, delta_x, delta_y;
+	int ret;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret != ARRAY_SIZE(msg)) {
+		dev_err(&client->dev,
+			"Failed I2C transfer in irq handler: %d\n",
+			ret < 0 ? ret : -EIO);
+		goto out;
+	}
+
+	if (msg2638_checksum((u8 *)&touch_event, len - 1) !=
+						touch_event.checksum) {
+		dev_err(&client->dev, "Failed checksum!\n");
+		goto out;
+	}
+
+	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)
+		goto report;
+
+	x = (((p0->xy_hi & 0xF0) << 4) | p0->x_low);
+	y = (((p0->xy_hi & 0x0F) << 8) | p0->y_low);
+
+	input_mt_slot(input, 0);
+	input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
+	touchscreen_report_pos(input, &msg2638->prop, x, y, true);
+
+	/* Ignore non-pressed finger data */
+	if (p1->xy_hi == 0xFF && p1->x_low == 0xFF && p1->y_low == 0xFF)
+		goto report;
+
+	/* Second finger is reported as a delta position */
+	delta_x = (((p1->xy_hi & 0xF0) << 4) | p1->x_low);
+	delta_y = (((p1->xy_hi & 0x0F) << 8) | p1->y_low);
+
+	/* Ignore second finger if both deltas equal 0 */
+	if (delta_x == 0 && delta_y == 0)
+		goto report;
+
+	x += delta_x;
+	y += delta_y;
+
+	input_mt_slot(input, 1);
+	input_mt_report_slot_state(input, MT_TOOL_FINGER, true);
+	touchscreen_report_pos(input, &msg2638->prop, x, y, true);
+
+report:
+	input_mt_sync_frame(msg2638->input_dev);
+	input_sync(msg2638->input_dev);
+
+out:
+	return IRQ_HANDLED;
+}
+
 static irqreturn_t msg2638_ts_irq_handler(int irq, void *msg2638_handler)
 {
 	struct msg2638_ts_data *msg2638 = msg2638_handler;
@@ -331,12 +418,18 @@ static int __maybe_unused msg2638_resume(struct device *dev)
 
 static SIMPLE_DEV_PM_OPS(msg2638_pm_ops, msg2638_suspend, msg2638_resume);
 
+static const struct msg_chip_data msg2138_data = {
+	.irq_handler = msg2138_ts_irq_handler,
+	.max_fingers = MSG2138_MAX_FINGERS,
+};
+
 static const struct msg_chip_data msg2638_data = {
 	.irq_handler = msg2638_ts_irq_handler,
 	.max_fingers = MSG2638_MAX_FINGERS,
 };
 
 static const struct of_device_id msg2638_of_match[] = {
+	{ .compatible = "mstar,msg2138", .data = &msg2138_data },
 	{ .compatible = "mstar,msg2638", .data = &msg2638_data },
 	{ }
 };
-- 
2.31.1

[PATCH 4/5] dt-bindings: input: touchscreen: msg2638: Document keys support

[Vincent Knecht]

Document optional linux,keycodes support.

Signed-off-by: Vincent Knecht <vincent.knecht@mailoo.org>
---
 .../devicetree/bindings/input/touchscreen/mstar,msg2638.yaml  | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
index 2fb7e01bb65a..af4f954de958 100644
--- a/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
+++ b/Documentation/devicetree/bindings/input/touchscreen/mstar,msg2638.yaml
@@ -36,6 +36,10 @@ properties:
   touchscreen-size-x: true
   touchscreen-size-y: true
 
+  linux,keycodes:
+    minItems: 1
+    maxItems: 4
+
 additionalProperties: false
 
 required:
-- 
2.31.1