[PATCH 2/4] Input: goodix - Allow tweaking of configuration file dynamically

[Franklin S Cooper Jr <fcooper@ti.com>]

Some goodix touchscreen controllers don't have the correct configuration
firmware for the display panel it is attached to. Therefore, settings such
as touchscreen x and y size may need to be passed in via DT and have the
panel reprogrammed for the updated touchscreen resolution.

This patchset adds support for reading the current configuration firmware
on the panel and allowing it to be modified and rewritten back to the
device.

Currently this function is unused but later patches will make use of it.

Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
---
 drivers/input/touchscreen/goodix.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/drivers/input/touchscreen/goodix.c b/drivers/input/touchscreen/goodix.c
index a43c8ca..01e12f8 100644
--- a/drivers/input/touchscreen/goodix.c
+++ b/drivers/input/touchscreen/goodix.c
@@ -478,6 +478,34 @@ static int goodix_get_gpio_config(struct goodix_ts_data *ts)
 	return 0;
 }
 
+static void goodix_tweak_config(struct goodix_ts_data *ts)
+{
+	u8 config[GOODIX_CONFIG_MAX_LENGTH];
+	int error;
+	int raw_cfg_len;
+	u8 check_sum = 0;
+
+	raw_cfg_len = ts->cfg_len - 2;
+
+	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), avoid tweaking config\n",
+			 error);
+		return;
+	}
+
+	check_sum = goodix_calculate_checksum(ts->cfg_len, config);
+
+	config[raw_cfg_len] = check_sum;
+	config[raw_cfg_len + 1] = 1;
+
+	error = goodix_send_cfg(ts, ts->cfg_len, config);
+	if (error)
+		dev_warn(&ts->client->dev,
+			 "Error writing config (%d)\n", error);
+}
 /**
  * goodix_read_config - Read the embedded configuration of the panel
  *
-- 
2.10.0