platform/x86: system76_acpi: Add attribute group for kb_led_color

Create the attribute groups for kb_led_color and set the `groups` field
in kb_led. While touching it, also change its show method to use
sysfs_emit() instead of sprintf().
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Link: https://lore.kernel.org/r/20211006202202.7479-5-tcrawford@system76.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

drivers/platform/x86/system76_acpi.c

@@ -348,7 +348,7 @@ static ssize_t kb_led_color_show(
 
 	led = (struct led_classdev *)dev->driver_data;
 	data = container_of(led, struct system76_data, kb_led);
-	return sprintf(buf, "%06X\n", data->kb_color);
+	return sysfs_emit(buf, "%06X\n", data->kb_color);
 }
 
 // Set the keyboard LED color
@@ -376,7 +376,7 @@ static ssize_t kb_led_color_store(
 	return size;
 }
 
-static const struct device_attribute kb_led_color_dev_attr = {
+static struct device_attribute dev_attr_kb_led_color = {
 	.attr = {
 		.name = "color",
 		.mode = 0644,
@@ -385,6 +385,13 @@ static const struct device_attribute kb_led_color_dev_attr = {
 	.store = kb_led_color_store,
 };
 
+static struct attribute *system76_kb_led_color_attrs[] = {
+	&dev_attr_kb_led_color.attr,
+	NULL,
+};
+
+ATTRIBUTE_GROUPS(system76_kb_led_color);
+
 // Notify that the keyboard LED was changed by hardware
 static void kb_led_notify(struct system76_data *data)
 {
@@ -685,6 +692,7 @@ static int system76_add(struct acpi_device *acpi_dev)
 	data->kb_led.brightness_set_blocking = kb_led_set;
 	if (acpi_has_method(acpi_device_handle(data->acpi_dev), "SKBC")) {
 		data->kb_led.max_brightness = 255;
+		data->kb_led.groups = system76_kb_led_color_groups;
 		data->kb_toggle_brightness = 72;
 		data->kb_color = 0xffffff;
 		system76_set(data, "SKBC", data->kb_color);
@@ -696,15 +704,6 @@ static int system76_add(struct acpi_device *acpi_dev)
 	if (err)
 		return err;
 
-	if (data->kb_color >= 0) {
-		err = device_create_file(
-			data->kb_led.dev,
-			&kb_led_color_dev_attr
-		);
-		if (err)
-			return err;
-	}
-
 	data->input = devm_input_allocate_device(&acpi_dev->dev);
 	if (!data->input)
 		return -ENOMEM;
@@ -753,9 +752,6 @@ static int system76_remove(struct acpi_device *acpi_dev)
 
 	system76_battery_exit();
 
-	if (data->kb_color >= 0)
-		device_remove_file(data->kb_led.dev, &kb_led_color_dev_attr);
-
 	devm_led_classdev_unregister(&acpi_dev->dev, &data->ap_led);
 	devm_led_classdev_unregister(&acpi_dev->dev, &data->kb_led);