Input: edt-ft5x06 - calculate points data length only once

It is pointless and expensive to calculate data in the interrupt that
depends on the type of touchscreen, which is detected on the driver
probe and cannot then be changed.
So calculate the size of the data buffer on the driver probe, as well as
the data retrieval command, and then use them in the ISR.

Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/r/20230402200951.1032513-10-dario.binacchi@amarulasolutions.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

Author: passgat

drivers/input/touchscreen/edt-ft5x06.c

@@ -135,6 +135,10 @@ struct edt_ft5x06_ts_data {
 	int offset_y;
 	int report_rate;
 	int max_support_points;
+	int point_len;
+	u8 tdata_cmd;
+	int tdata_len;
+	int tdata_offset;
 
 	char name[EDT_NAME_LEN];
 	char fw_version[EDT_NAME_LEN];
@@ -296,46 +300,21 @@ static irqreturn_t edt_ft5x06_ts_isr(int irq, void *dev_id)
 {
 	struct edt_ft5x06_ts_data *tsdata = dev_id;
 	struct device *dev = &tsdata->client->dev;
-	u8 cmd;
 	u8 rdbuf[63];
 	int i, type, x, y, id;
-	int offset, tplen, datalen, crclen;
 	int error;
 
-	switch (tsdata->version) {
-	case EDT_M06:
-		cmd = 0xf9; /* tell the controller to send touch data */
-		offset = 5; /* where the actual touch data starts */
-		tplen = 4;  /* data comes in so called frames */
-		crclen = 1; /* length of the crc data */
-		break;
-
-	case EDT_M09:
-	case EDT_M12:
-	case EV_FT:
-	case GENERIC_FT:
-		cmd = 0x0;
-		offset = 3;
-		tplen = 6;
-		crclen = 0;
-		break;
-
-	default:
-		goto out;
-	}
-
 	memset(rdbuf, 0, sizeof(rdbuf));
-	datalen = tplen * tsdata->max_support_points + offset + crclen;
-
-	error = regmap_bulk_read(tsdata->regmap, cmd, rdbuf, datalen);
+	error = regmap_bulk_read(tsdata->regmap, tsdata->tdata_cmd, rdbuf,
+				 tsdata->tdata_len);
 	if (error) {
 		dev_err_ratelimited(dev, "Unable to fetch data, error: %d\n",
 				    error);
 		goto out;
 	}
 
 	for (i = 0; i < tsdata->max_support_points; i++) {
-		u8 *buf = &rdbuf[i * tplen + offset];
+		u8 *buf = &rdbuf[i * tsdata->point_len + tsdata->tdata_offset];
 
 		type = buf[0] >> 6;
 		/* ignore Reserved events */
@@ -1071,6 +1050,26 @@ static void edt_ft5x06_ts_get_parameters(struct edt_ft5x06_ts_data *tsdata)
 	}
 }
 
+static void edt_ft5x06_ts_set_tdata_parameters(struct edt_ft5x06_ts_data *tsdata)
+{
+	int crclen;
+
+	if (tsdata->version == EDT_M06) {
+		tsdata->tdata_cmd = 0xf9;
+		tsdata->tdata_offset = 5;
+		tsdata->point_len = 4;
+		crclen = 1;
+	} else {
+		tsdata->tdata_cmd = 0x0;
+		tsdata->tdata_offset = 3;
+		tsdata->point_len = 6;
+		crclen = 0;
+	}
+
+	tsdata->tdata_len = tsdata->point_len * tsdata->max_support_points +
+		tsdata->tdata_offset + crclen;
+}
+
 static void edt_ft5x06_ts_set_regs(struct edt_ft5x06_ts_data *tsdata)
 {
 	struct edt_reg_addr *reg_addr = &tsdata->reg_addr;
@@ -1274,6 +1273,7 @@ static int edt_ft5x06_ts_probe(struct i2c_client *client)
 	 */
 	regmap_read(tsdata->regmap, 0x00, &val);
 
+	edt_ft5x06_ts_set_tdata_parameters(tsdata);
 	edt_ft5x06_ts_set_regs(tsdata);
 	edt_ft5x06_ts_get_defaults(&client->dev, tsdata);
 	edt_ft5x06_ts_get_parameters(tsdata);