Input: goodix - add sysfs interface to dump config

Goodix devices have a configuration information register area that
specifies various parameters for the device. The configuration information
has a specific format described in the Goodix datasheet. It includes X/Y
resolution, maximum supported touch points, interrupt flags, various
sesitivity factors and settings for advanced features (like gesture
recognition).

Export a sysfs interface that would allow reading the configuration
information. This interface will be available for all devices (even
if they cannot overwrite this configuration because the gpio pins are
not properly connected).

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>

drivers/input/touchscreen/goodix.c

@@ -430,6 +430,41 @@ static int goodix_reset(struct goodix_ts_data *ts)
 	return 0;
 }
 
+static ssize_t goodix_dump_config_show(struct device *dev,
+				       struct device_attribute *attr, char *buf)
+{
+	struct goodix_ts_data *ts = dev_get_drvdata(dev);
+	u8 config[GOODIX_CONFIG_MAX_LENGTH];
+	int error, count = 0, i;
+
+	if (ts->gpiod_int && ts->gpiod_rst)
+		wait_for_completion(&ts->firmware_loading_complete);
+
+	error = goodix_i2c_read(ts->client, GOODIX_REG_CONFIG_DATA,
+				config, ts->cfg_len);
+	if (error) {
+		dev_warn(&ts->client->dev,
+			 "Error reading config (%d)\n",  error);
+		return error;
+	}
+
+	for (i = 0; i < ts->cfg_len; i++)
+		count += scnprintf(buf + count, PAGE_SIZE - count, "%02x ",
+				   config[i]);
+	return count;
+}
+
+static DEVICE_ATTR(dump_config, S_IRUGO, goodix_dump_config_show, NULL);
+
+static struct attribute *goodix_attrs[] = {
+	&dev_attr_dump_config.attr,
+	NULL
+};
+
+static const struct attribute_group goodix_attr_group = {
+	.attrs = goodix_attrs,
+};
+
 /**
  * goodix_get_gpio_config - Get GPIO config from ACPI/DT
  *
@@ -734,12 +769,22 @@ static int goodix_ts_probe(struct i2c_client *client,
 
 	ts->cfg_len = goodix_get_cfg_len(ts->id);
 
+	error = sysfs_create_group(&client->dev.kobj,
+				   &goodix_attr_group);
+	if (error) {
+		dev_err(&client->dev, "Failed to create sysfs group: %d\n",
+			error);
+		return error;
+	}
+
 	if (ts->gpiod_int && ts->gpiod_rst) {
 		/* update device config */
 		ts->cfg_name = devm_kasprintf(&client->dev, GFP_KERNEL,
 					      "goodix_%d_cfg.bin", ts->id);
-		if (!ts->cfg_name)
-			return -ENOMEM;
+		if (!ts->cfg_name) {
+			error = -ENOMEM;
+			goto err_sysfs_remove_group;
+		}
 
 		error = request_firmware_nowait(THIS_MODULE, true, ts->cfg_name,
 						&client->dev, GFP_KERNEL, ts,
@@ -748,17 +793,21 @@ static int goodix_ts_probe(struct i2c_client *client,
 			dev_err(&client->dev,
 				"Failed to invoke firmware loader: %d\n",
 				error);
-			return error;
+			goto err_sysfs_remove_group;
 		}
 
 		return 0;
 	} else {
 		error = goodix_configure_dev(ts);
 		if (error)
-			return error;
+			goto err_sysfs_remove_group;
 	}
 
 	return 0;
+
+err_sysfs_remove_group:
+	sysfs_remove_group(&client->dev.kobj, &goodix_attr_group);
+	return error;
 }
 
 static int goodix_ts_remove(struct i2c_client *client)
@@ -768,6 +817,8 @@ static int goodix_ts_remove(struct i2c_client *client)
 	if (ts->gpiod_int && ts->gpiod_rst)
 		wait_for_completion(&ts->firmware_loading_complete);
 
+	sysfs_remove_group(&client->dev.kobj, &goodix_attr_group);
+
 	return 0;
 }