xpadneo, devices: Add support for synthetic devices

In preparation for mouse mode and keyboard emulation, we need to be
able to create virtual devices associated with the controller.

Signed-off-by: Kai Krakow <[email protected]>

hid-xpadneo/src/hid-xpadneo.c

@@ -1161,6 +1161,36 @@ static int xpadneo_init_hw(struct hid_device *hdev)
 	return ret;
 }
 
+static int xpadneo_init_synthetic(struct xpadneo_devdata *xdata, char *suffix,
+				  struct input_dev **devp)
+{
+	struct hid_device *hdev = xdata->hdev;
+	struct input_dev *input_dev = devm_input_allocate_device(&hdev->dev);
+	size_t suffix_len, name_len;
+
+	if (!input_dev)
+		return -ENOMEM;
+
+	name_len = strlen(hdev->name);
+	suffix_len = strlen(suffix);
+	if ((name_len < suffix_len) || strcmp(xdata->hdev->name + name_len - suffix_len, suffix)) {
+		input_dev->name = kasprintf(GFP_KERNEL, "%s %s", hdev->name, suffix);
+		if (!input_dev->name)
+			return -ENOMEM;
+	}
+
+	dev_set_drvdata(&input_dev->dev, xdata);
+	input_dev->phys = hdev->phys;
+	input_dev->uniq = hdev->uniq;
+	input_dev->id.bustype = hdev->bus;
+	input_dev->id.vendor = hdev->vendor;
+	input_dev->id.product = hdev->product;
+	input_dev->id.version = hdev->version;
+
+	*devp = input_dev;
+	return 0;
+}
+
 static int xpadneo_probe(struct hid_device *hdev, const struct hid_device_id *id)
 {
 	int ret;