Input: edt-ft5x06 - show crc and header errors by sysfs

M06 sends packets with header and crc for data verification. Now you can
check at runtime how many packets have been dropped.
Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Link: https://lore.kernel.org/r/20220621123937.1330389-7-dario.binacchi@amarulasolutions.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/edt-ft5x06.c

@@ -134,6 +134,8 @@ struct edt_ft5x06_ts_data {
 
 	struct edt_reg_addr reg_addr;
 	enum edt_ver version;
+	unsigned int crc_errors;
+	unsigned int header_errors;
 };
 
 struct edt_i2c_chip_data {
@@ -182,6 +184,7 @@ static bool edt_ft5x06_ts_check_crc(struct edt_ft5x06_ts_data *tsdata,
 		crc ^= buf[i];
 
 	if (crc != buf[buflen-1]) {
+		tsdata->crc_errors++;
 		dev_err_ratelimited(&tsdata->client->dev,
 				    "crc error: 0x%02x expected, got 0x%02x\n",
 				    crc, buf[buflen-1]);
@@ -239,6 +242,7 @@ static irqreturn_t edt_ft5x06_ts_isr(int irq, void *dev_id)
 	if (tsdata->version == EDT_M06) {
 		if (rdbuf[0] != 0xaa || rdbuf[1] != 0xaa ||
 			rdbuf[2] != datalen) {
+			tsdata->header_errors++;
 			dev_err_ratelimited(dev,
 					"Unexpected header: %02x%02x%02x!\n",
 					rdbuf[0], rdbuf[1], rdbuf[2]);
@@ -553,6 +557,30 @@ static ssize_t fw_version_show(struct device *dev,
 
 static DEVICE_ATTR_RO(fw_version);
 
+/* m06 only */
+static ssize_t header_errors_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
+
+	return sysfs_emit(buf, "%d\n", tsdata->header_errors);
+}
+
+static DEVICE_ATTR_RO(header_errors);
+
+/* m06 only */
+static ssize_t crc_errors_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct edt_ft5x06_ts_data *tsdata = i2c_get_clientdata(client);
+
+	return sysfs_emit(buf, "%d\n", tsdata->crc_errors);
+}
+
+static DEVICE_ATTR_RO(crc_errors);
+
 static struct attribute *edt_ft5x06_attrs[] = {
 	&edt_ft5x06_attr_gain.dattr.attr,
 	&edt_ft5x06_attr_offset.dattr.attr,
@@ -562,6 +590,8 @@ static struct attribute *edt_ft5x06_attrs[] = {
 	&edt_ft5x06_attr_report_rate.dattr.attr,
 	&dev_attr_model.attr,
 	&dev_attr_fw_version.attr,
+	&dev_attr_header_errors.attr,
+	&dev_attr_crc_errors.attr,
 	NULL
 };