linux-kernel - [PATCH v6 2/5] input: elants: support old touch report format

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Message-Id: <7acd9534663ec8c35390dbd938fd212327c3f05f.1594599118.git.mirq-linux@rere.qmqm.pl>
Date:   Mon, 13 Jul 2020 02:24:54 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Dmitry Osipenko <digetx@...il.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Henrik Rydberg <rydberg@...math.org>,
        James Chen <james.chen@....com.tw>,
        Johnny Chuang <johnny.chuang@....com.tw>,
        Scott Liu <scott.liu@....com.tw>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v6 2/5] input: elants: support old touch report format

Support ELAN touchpad sensor with older firmware as found on eg. Asus
Transformer Pads.

Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
Reviewed-by: Dmitry Osipenko <digetx@...il.com>
Tested-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/input/touchscreen/elants_i2c.c | 36 ++++++++++++++++++--------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index fa4a2f6b69c6..ba1816d08530 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c
@@ -69,6 +69,7 @@
 #define CMD_HEADER_REK		0x66
 
 /* FW position data */
+#define PACKET_SIZE_OLD		40
 #define PACKET_SIZE		55
 #define MAX_CONTACT_NUM		10
 #define FW_POS_HEADER		0
@@ -849,7 +850,8 @@ static int elants_i2c_fw_update(struct elants_data *ts)
  * Event reporting.
  */
 
-static void elants_i2c_mt_event(struct elants_data *ts, u8 *buf)
+static void elants_i2c_mt_event(struct elants_data *ts, u8 *buf,
+				size_t report_len)
 {
 	struct input_dev *input = ts->input;
 	unsigned int n_fingers;
@@ -862,7 +864,8 @@ static void elants_i2c_mt_event(struct elants_data *ts, u8 *buf)
 			buf[FW_POS_STATE];
 
 	dev_dbg(&ts->client->dev,
-		"n_fingers: %u, state: %04x\n",  n_fingers, finger_state);
+		"n_fingers: %u, state: %04x, report_len: %zu\n",
+		n_fingers, finger_state, report_len);
 
 	/* Note: all fingers have the same tool type */
 	tool_type = buf[FW_POS_TOOL_TYPE] & BIT(0) ?
@@ -876,8 +879,16 @@ static void elants_i2c_mt_event(struct elants_data *ts, u8 *buf)
 			pos = &buf[FW_POS_XY + i * 3];
 			x = (((u16)pos[0] & 0xf0) << 4) | pos[1];
 			y = (((u16)pos[0] & 0x0f) << 8) | pos[2];
-			p = buf[FW_POS_PRESSURE + i];
-			w = buf[FW_POS_WIDTH + i];
+			if (report_len == PACKET_SIZE_OLD) {
+				w = buf[FW_POS_WIDTH + i / 2];
+				w >>= 4 * (~i & 1);	// little-endian-nibbles
+				w |= w << 4;
+				w |= !w;
+				p = w;
+			} else {
+				p = buf[FW_POS_PRESSURE + i];
+				w = buf[FW_POS_WIDTH + i];
+			}
 
 			dev_dbg(&ts->client->dev, "i=%d x=%d y=%d p=%d w=%d\n",
 				i, x, y, p, w);
@@ -909,7 +920,8 @@ static u8 elants_i2c_calculate_checksum(u8 *buf)
 	return checksum;
 }
 
-static void elants_i2c_event(struct elants_data *ts, u8 *buf)
+static void elants_i2c_event(struct elants_data *ts, u8 *buf,
+			     size_t report_len)
 {
 	u8 checksum = elants_i2c_calculate_checksum(buf);
 
@@ -923,7 +935,7 @@ static void elants_i2c_event(struct elants_data *ts, u8 *buf)
 			 "%s: unknown packet type: %02x\n",
 			 __func__, buf[FW_POS_HEADER]);
 	else
-		elants_i2c_mt_event(ts, buf);
+		elants_i2c_mt_event(ts, buf, report_len);
 }
 
 static irqreturn_t elants_i2c_irq(int irq, void *_dev)
@@ -981,7 +993,8 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
 			break;
 
 		case QUEUE_HEADER_SINGLE:
-			elants_i2c_event(ts, &ts->buf[HEADER_SIZE]);
+			elants_i2c_event(ts, &ts->buf[HEADER_SIZE],
+					 ts->buf[FW_HDR_LENGTH]);
 			break;
 
 		case QUEUE_HEADER_NORMAL:
@@ -994,17 +1007,18 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
 			}
 
 			report_len = ts->buf[FW_HDR_LENGTH] / report_count;
-			if (report_len != PACKET_SIZE) {
+			if (report_len != PACKET_SIZE &&
+			    report_len != PACKET_SIZE_OLD) {
 				dev_err(&client->dev,
-					"mismatching report length: %*ph\n",
+					"unsupported report length: %*ph\n",
 					HEADER_SIZE, ts->buf);
 				break;
 			}
 
 			for (i = 0; i < report_count; i++) {
 				u8 *buf = ts->buf + HEADER_SIZE +
-							i * PACKET_SIZE;
-				elants_i2c_event(ts, buf);
+					  i * report_len;
+				elants_i2c_event(ts, buf, report_len);
 			}
 			break;
 
-- 
2.20.1