[PATCH v12 1/5] Input: goodix - add sysfs interface to dump config

[Irina Tirdea <irina.tirdea@intel.com>]

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. The default device configuration can be used as a starting
point for creating a valid configuration firmware used by the device at
init time to update its configuration.

This sysfs interface will be exported only if the gpio pins are properly
initialized from ACPI/DT.

Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
---
 Documentation/input/goodix.txt     | 84 ++++++++++++++++++++++++++++++++++++++
 drivers/input/touchscreen/goodix.c | 64 ++++++++++++++++++++++++++---
 2 files changed, 143 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/input/goodix.txt

diff --git a/Documentation/input/goodix.txt b/Documentation/input/goodix.txt
new file mode 100644
index 0000000..f9be1e2
--- /dev/null
+++ b/Documentation/input/goodix.txt
@@ -0,0 +1,84 @@
+Goodix touchscreen driver
+=====================================
+
+How to update configuration firmware
+=====================================
+
+Goodix touchscreen devices have a set of registers that specify configuration
+information 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).
+
+The devices have an initial default configuration that can be read through
+the sysfs interface (/sys/class/input/inputX/device/dump_config). This default
+configuration can be used as a starting point for creating a new configuration
+firmware file. At init, the driver will read the configuration firmware file
+and update the device configuration.
+
+This configuration can be accesed only if both interrupt and reset gpio pins
+are connected and properly configured through ACPI _DSD/DT properties.
+
+Below are instructions on how to generate a valid configuration starting from
+the device default configuration.
+
+1. Dump the default configuration of the device to a file:
+  $ cat /sys/class/input/inputX/device/dump_config > goodix_<model>_cfg
+
+2. Make the needed changes to the configuration (e.g. change resolution of
+x/y axes, maximum reported touch points, switch X,Y axes, etc.). For more
+details check the Goodix datasheet for format of Configuration Registers.
+
+3. Generate a valid configuration starting from  goodix_<model>_cfg.
+After making changes, you need to recompute the checksum of the entire
+configuration data, set Config_Fresh to 1 and generate the binary config
+firmware image. This can be done using a helper script similar to the
+one below:
+
+#!/bin/bash
+
+if [[ $# -lt 1 ]]; then
+    echo "$0 fw_filename"
+    exit 1
+fi
+
+file_in="$1"
+file_out_bin=${file_in}.bin
+
+print_val ()
+{
+    val="$1"
+    printf "0x%.2x" "$val" | xxd -r -p >> ${file_out_bin}
+}
+
+rm -f ${file_out_bin}
+
+size=`cat ${file_in} | wc -w`
+
+checksum=0
+i=1
+for val in `cat ${file_in}`; do
+    val="0x$val"
+    if [[ $i == $size ]]; then
+	# Config_Fresh
+	print_val 0x01
+    elif [[ $i == $((size-1)) ]]; then
+	# Config_Chksum
+	checksum=$(( (~ checksum + 1) & 0xFF))
+	print_val $checksum
+    else
+	checksum=$((checksum + val))
+	print_val $val
+    fi
+    i=$((i+1))
+done
+
+echo "Wrote ${file_out_bin}"
+
+4. Copy the binary config firmware in the appropriate location
+(e.g. /lib/firmware), using the name goodix_<model>_cfg.bin (e.g. for gt911,
+use goodix_911_cfg.bin).
+
+5. Check that the new firmware was successfully written to the device
+after reboot. Config_Fresh is reset to 0 after a successful update of the
+configuration.
diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index 240b16f..2447b73 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -430,6 +430,40 @@ 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;
+
+	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
  *
@@ -735,11 +769,22 @@ static int goodix_ts_probe(struct i2c_client *client,
 	ts->cfg_len = goodix_get_cfg_len(ts->id);
 
 	if (ts->gpiod_int && ts->gpiod_rst) {
+		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;
+		}
+
 		/* 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,
@@ -748,7 +793,7 @@ 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;
@@ -759,14 +804,23 @@ static int goodix_ts_probe(struct i2c_client *client,
 	}
 
 	return 0;
+
+err_sysfs_remove_group:
+	if (ts->gpiod_int && ts->gpiod_rst)
+		sysfs_remove_group(&client->dev.kobj, &goodix_attr_group);
+	return error;
 }
 
 static int goodix_ts_remove(struct i2c_client *client)
 {
 	struct goodix_ts_data *ts = i2c_get_clientdata(client);
 
-	if (ts->gpiod_int && ts->gpiod_rst)
-		wait_for_completion(&ts->firmware_loading_complete);
+	if (!ts->gpiod_int || !ts->gpiod_rst)
+		return 0;
+
+	wait_for_completion(&ts->firmware_loading_complete);
+
+	sysfs_remove_group(&client->dev.kobj, &goodix_attr_group);
 
 	return 0;
 }
-- 
1.9.1