HID: wacom: EKR: use devres groups to manage resources

This will be useful when each remote will be assigned its own input device.
We won't need to unregister each input and sysfs and other elements one
at a time.
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/wacom_sys.c

@@ -934,8 +934,9 @@ static void wacom_devm_sysfs_group_release(struct device *dev, void *res)
 	sysfs_remove_group(kobj, devres->group);
 }
 
-static int wacom_devm_sysfs_create_group(struct wacom *wacom,
-					 struct attribute_group *group)
+static int __wacom_devm_sysfs_create_group(struct wacom *wacom,
+					   struct kobject *root,
+					   struct attribute_group *group)
 {
 	struct wacom_sysfs_group_devres *devres;
 	int error;
@@ -947,7 +948,7 @@ static int wacom_devm_sysfs_create_group(struct wacom *wacom,
 		return -ENOMEM;
 
 	devres->group = group;
-	devres->root = &wacom->hdev->dev.kobj;
+	devres->root = root;
 
 	error = sysfs_create_group(devres->root, group);
 	if (error)
@@ -958,6 +959,13 @@ static int wacom_devm_sysfs_create_group(struct wacom *wacom,
 	return 0;
 }
 
+static int wacom_devm_sysfs_create_group(struct wacom *wacom,
+					 struct attribute_group *group)
+{
+	return __wacom_devm_sysfs_create_group(wacom, &wacom->hdev->dev.kobj,
+					       group);
+}
+
 static void wacom_led_groups_release(void *data)
 {
 	struct wacom *wacom = data;
@@ -1306,9 +1314,10 @@ static int wacom_remote_create_attr_group(struct wacom *wacom, __u32 serial,
 	if (!remote->remote_group[index].name)
 		return -ENOMEM;
 
-	error = sysfs_create_group(remote->remote_dir,
-				   &remote->remote_group[index]);
+	error = __wacom_devm_sysfs_create_group(wacom, remote->remote_dir,
+						&remote->remote_group[index]);
 	if (error) {
+		remote->remote_group[index].name = NULL;
 		hid_err(wacom->hdev,
 			"cannot create sysfs group err: %d\n", error);
 		return error;
@@ -1317,15 +1326,6 @@ static int wacom_remote_create_attr_group(struct wacom *wacom, __u32 serial,
 	return 0;
 }
 
-static void wacom_remote_destroy_attr_group(struct wacom *wacom, unsigned int i)
-{
-	struct wacom_remote *remote = wacom->remote;
-
-	sysfs_remove_group(remote->remote_dir, &remote->remote_group[i]);
-	devm_kfree(&wacom->hdev->dev, (char *)remote->remote_group[i].name);
-	remote->remote_group[i].name = NULL;
-}
-
 static int wacom_cmd_unpair_remote(struct wacom *wacom, unsigned char selector)
 {
 	const size_t buf_size = 2;
@@ -1906,11 +1906,13 @@ static void wacom_remote_destroy_one(struct wacom *wacom, unsigned int index)
 	u32 serial = remote->serial[index];
 	int i;
 
-	wacom_remote_destroy_attr_group(wacom, index);
+	if (remote->remote_group[index].name)
+		devres_release_group(&wacom->hdev->dev, &remote->serial[index]);
 
 	for (i = 0; i < WACOM_MAX_REMOTES; i++) {
 		if (remote->serial[i] == serial) {
 			remote->serial[i] = 0;
+			remote->remote_group[i].name = NULL;
 			wacom->led.groups[i].select = WACOM_STATUS_UNKNOWN;
 		}
 	}
@@ -1920,6 +1922,7 @@ static int wacom_remote_create_one(struct wacom *wacom, u32 serial,
 				   unsigned int index)
 {
 	struct wacom_remote *remote = wacom->remote;
+	struct device *dev = &wacom->hdev->dev;
 	int error, k;
 
 	/* A remote can pair more than once with an EKR,
@@ -1935,13 +1938,22 @@ static int wacom_remote_create_one(struct wacom *wacom, u32 serial,
 		return 0;
 	}
 
+	if (!devres_open_group(dev, &remote->serial[index], GFP_KERNEL))
+		return -ENOMEM;
+
 	error = wacom_remote_create_attr_group(wacom, serial, index);
 	if (error)
-		return error;
+		goto fail;
 
 	remote->serial[index] = serial;
 
+	devres_close_group(dev, &remote->serial[index]);
 	return 0;
+
+fail:
+	devres_release_group(dev, &remote->serial[index]);
+	remote->serial[index] = 0;
+	return error;
 }
 
 static void wacom_remote_work(struct work_struct *work)