linux-kernel - [PATCH 1/2] Input: wacom_i2c - Clean up the query device fields

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Message-Id: <20211009113707.17568-1-alistair@alistair23.me>
Date:   Sat,  9 Oct 2021 21:37:06 +1000
From:   Alistair Francis <alistair@...stair23.me>
To:     dmitry.torokhov@...il.com, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     alistair@...stair23.me, alistair23@...il.com
Subject: [PATCH 1/2] Input: wacom_i2c - Clean up the query device fields

Improve the query device fields to be more verbose.

Signed-off-by: Alistair Francis <alistair@...stair23.me>
---
 drivers/input/touchscreen/wacom_i2c.c | 49 ++++++++++++++++-----------
 1 file changed, 30 insertions(+), 19 deletions(-)

diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
index 22826c387da5..8d7267ccc661 100644
--- a/drivers/input/touchscreen/wacom_i2c.c
+++ b/drivers/input/touchscreen/wacom_i2c.c
@@ -14,13 +14,21 @@
 #include <linux/interrupt.h>
 #include <asm/unaligned.h>
 
-#define WACOM_CMD_QUERY0	0x04
-#define WACOM_CMD_QUERY1	0x00
-#define WACOM_CMD_QUERY2	0x33
-#define WACOM_CMD_QUERY3	0x02
-#define WACOM_CMD_THROW0	0x05
-#define WACOM_CMD_THROW1	0x00
-#define WACOM_QUERY_SIZE	19
+// Registers
+#define WACOM_COMMAND_LSB   0x04
+#define WACOM_COMMAND_MSB   0x00
+
+#define WACOM_DATA_LSB      0x05
+#define WACOM_DATA_MSB      0x00
+
+// Report types
+#define REPORT_FEATURE      0x30
+
+// Requests / operations
+#define OPCODE_GET_REPORT   0x02
+
+#define WACOM_QUERY_REPORT	3
+#define WACOM_QUERY_SIZE	22
 
 struct wacom_features {
 	int x_max;
@@ -41,27 +49,30 @@ static int wacom_query_device(struct i2c_client *client,
 			      struct wacom_features *features)
 {
 	int ret;
-	u8 cmd1[] = { WACOM_CMD_QUERY0, WACOM_CMD_QUERY1,
-			WACOM_CMD_QUERY2, WACOM_CMD_QUERY3 };
-	u8 cmd2[] = { WACOM_CMD_THROW0, WACOM_CMD_THROW1 };
 	u8 data[WACOM_QUERY_SIZE];
+
+	u8 get_query_data_cmd[] = {
+		WACOM_COMMAND_LSB,
+		WACOM_COMMAND_MSB,
+		REPORT_FEATURE | WACOM_QUERY_REPORT,
+		OPCODE_GET_REPORT,
+		WACOM_DATA_LSB,
+		WACOM_DATA_MSB,
+	};
+
 	struct i2c_msg msgs[] = {
+		// Request reading of feature ReportID: 3 (Pen Query Data)
 		{
 			.addr = client->addr,
 			.flags = 0,
-			.len = sizeof(cmd1),
-			.buf = cmd1,
-		},
-		{
-			.addr = client->addr,
-			.flags = 0,
-			.len = sizeof(cmd2),
-			.buf = cmd2,
+			.len = sizeof(get_query_data_cmd),
+			.buf = get_query_data_cmd,
 		},
+		// Read 21 bytes
 		{
 			.addr = client->addr,
 			.flags = I2C_M_RD,
-			.len = sizeof(data),
+			.len = WACOM_QUERY_SIZE - 1,
 			.buf = data,
 		},
 	};
-- 
2.31.1