[PATCH v3 1/2] platform/x86: dell-uart-backlight: extract dell_uart_bl_init() from probe

[chitranshmandhaniya@gmail.com]

From: Chitransh Mandhaniya <Chitransh_Mandhaniya@dell.com>

Move the UART backlight initialization sequence (get_version,
set_bl_power, get_brightness and backlight device registration) out of
dell_uart_bl_serdev_probe() into a new dell_uart_bl_init() helper.

No functional change. This is a preparatory refactor so that a
follow-up patch can inspect the return value of dell_uart_bl_init()
and take an alternative code path on failure.

Tested on OptiPlex AIO 7410 35W (01KP8D) and OptiPlex AIO 7420 35W
(0914RT) -- driver behaviour unchanged, backlight probes identically.

Signed-off-by: Chitransh Mandhaniya <Chitransh_Mandhaniya@dell.com>
---
 .../platform/x86/dell/dell-uart-backlight.c   | 59 ++++++++++---------
 1 file changed, 32 insertions(+), 27 deletions(-)

diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c
index f323a667dc2d..e3b7f1beda5b 100644
--- a/drivers/platform/x86/dell/dell-uart-backlight.c
+++ b/drivers/platform/x86/dell/dell-uart-backlight.c
@@ -267,40 +267,19 @@ static const struct serdev_device_ops dell_uart_bl_serdev_ops = {
 	.write_wakeup = serdev_device_write_wakeup,
 };
 
-static int dell_uart_bl_serdev_probe(struct serdev_device *serdev)
+static int dell_uart_bl_init(struct device *dev, struct dell_uart_backlight *dell_bl)
 {
 	u8 get_version[GET_CMD_LEN], resp[MAX_RESP_LEN];
 	struct backlight_properties props = {};
-	struct dell_uart_backlight *dell_bl;
-	struct device *dev = &serdev->dev;
 	int ret;
 
-	dell_bl = devm_kzalloc(dev, sizeof(*dell_bl), GFP_KERNEL);
-	if (!dell_bl)
-		return -ENOMEM;
-
-	mutex_init(&dell_bl->mutex);
-	init_waitqueue_head(&dell_bl->wait_queue);
-	dell_bl->dev = dev;
-
-	serdev_device_set_drvdata(serdev, dell_bl);
-	serdev_device_set_client_ops(serdev, &dell_uart_bl_serdev_ops);
-
-	ret = devm_serdev_device_open(dev, serdev);
-	if (ret)
-		return dev_err_probe(dev, ret, "opening UART device\n");
-
-	/* 9600 bps, no flow control, these are the default but set them to be sure */
-	serdev_device_set_baudrate(serdev, 9600);
-	serdev_device_set_flow_control(serdev, false);
-
 	get_version[0] = DELL_SOF(GET_CMD_LEN);
 	get_version[1] = CMD_GET_VERSION;
 	get_version[2] = dell_uart_checksum(get_version, 2);
 
 	ret = dell_uart_bl_command(dell_bl, get_version, GET_CMD_LEN, resp, MAX_RESP_LEN);
 	if (ret)
-		return dev_err_probe(dev, ret, "getting firmware version\n");
+		return ret;
 
 	dev_dbg(dev, "Firmware version: %.*s\n", resp[RESP_LEN] - 3, resp + RESP_DATA);
 
@@ -318,13 +297,39 @@ static int dell_uart_bl_serdev_probe(struct serdev_device *serdev)
 	props.max_brightness = DELL_BL_MAX_BRIGHTNESS;
 	props.power = dell_bl->power;
 
-	dell_bl->bl = devm_backlight_device_register(dev, "dell_uart_backlight",
-						     dev, dell_bl,
-						     &dell_uart_backlight_ops,
-						     &props);
+	dell_bl->bl = devm_backlight_device_register(dev, "dell_uart_backlight", dev, dell_bl,
+						     &dell_uart_backlight_ops, &props);
 	return PTR_ERR_OR_ZERO(dell_bl->bl);
 }
 
+static int dell_uart_bl_serdev_probe(struct serdev_device *serdev)
+{
+	struct dell_uart_backlight *dell_bl;
+	struct device *dev = &serdev->dev;
+	int ret;
+
+	dell_bl = devm_kzalloc(dev, sizeof(*dell_bl), GFP_KERNEL);
+	if (!dell_bl)
+		return -ENOMEM;
+
+	mutex_init(&dell_bl->mutex);
+	init_waitqueue_head(&dell_bl->wait_queue);
+	dell_bl->dev = dev;
+
+	serdev_device_set_drvdata(serdev, dell_bl);
+	serdev_device_set_client_ops(serdev, &dell_uart_bl_serdev_ops);
+
+	ret = devm_serdev_device_open(dev, serdev);
+	if (ret)
+		return dev_err_probe(dev, ret, "opening UART device\n");
+
+	/* 9600 bps, no flow control, these are the default but set them to be sure */
+	serdev_device_set_baudrate(serdev, 9600);
+	serdev_device_set_flow_control(serdev, false);
+
+	return dell_uart_bl_init(dev, dell_bl);
+}
+
 static struct serdev_device_driver dell_uart_bl_serdev_driver = {
 	.probe = dell_uart_bl_serdev_probe,
 	.driver = {
-- 
2.43.0