drivers/hid/hid-vrc2.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * HID driver for VRC-2 2-axis Car controller
 *
 * Copyright (C) 2022 Marcus Folkesson <marcus.folkesson@gmail.com>
 */

#include <linux/device.h>
#include <linux/hid.h>
#include <linux/module.h>

/*
 * VID/PID are probably "borrowed", so keep them locally and
 * do not populate hid-ids.h with those.
 */
#define USB_VENDOR_ID_VRC2	(0x07c0)
#define USB_DEVICE_ID_VRC2	(0x1125)

static const __u8 vrc2_rdesc_fixed[] = {
	0x05, 0x01,        // Usage Page (Generic Desktop Ctrls)
	0x09, 0x04,        // Usage (Joystick)
	0xA1, 0x01,        // Collection (Application)
	0x09, 0x01,        //   Usage (Pointer)
	0xA1, 0x00,        //   Collection (Physical)
	0x09, 0x30,        //     Usage (X)
	0x09, 0x31,        //     Usage (Y)
	0x15, 0x00,        //     Logical Minimum (0)
	0x26, 0xFF, 0x07,  //     Logical Maximum (2047)
	0x35, 0x00,        //     Physical Minimum (0)
	0x46, 0xFF, 0x00,  //     Physical Maximum (255)
	0x75, 0x10,        //     Report Size (16)
	0x95, 0x02,        //     Report Count (2)
	0x81, 0x02,        //     Input (Data,Var,Abs,No Wrap,Linear,Preferred State,No Null Position)
	0xC0,              //   End Collection
	0x75, 0x08,        //   Report Size (8)
	0x95, 0x03,        //   Report Count (3)
	0x81, 0x03,        //   Input (Cnst,Var,Abs)
	0xC0,              // End Collection
};

static const __u8 *vrc2_report_fixup(struct hid_device *hdev, __u8 *rdesc,
				     unsigned int *rsize)
{
	hid_info(hdev, "fixing up VRC-2 report descriptor\n");
	*rsize = sizeof(vrc2_rdesc_fixed);
	return vrc2_rdesc_fixed;
}

static int vrc2_probe(struct hid_device *hdev, const struct hid_device_id *id)
{
	int ret;

	/*
	 * The device gives us 2 separate USB endpoints.
	 * One of those (the one with report descriptor size of 23) is just bogus so ignore it
	 */
	if (hdev->dev_rsize == 23)
		return -ENODEV;

	ret = hid_parse(hdev);
	if (ret) {
		hid_err(hdev, "parse failed\n");
		return ret;
	}

	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
	if (ret) {
		hid_err(hdev, "hw start failed\n");
		return ret;
	}

	return 0;
}

static const struct hid_device_id vrc2_devices[] = {
	{ HID_USB_DEVICE(USB_VENDOR_ID_VRC2, USB_DEVICE_ID_VRC2) },
	{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(hid, vrc2_devices);

static struct hid_driver vrc2_driver = {
	.name = "vrc2",
	.id_table = vrc2_devices,
	.report_fixup = vrc2_report_fixup,
	.probe = vrc2_probe,
};
module_hid_driver(vrc2_driver);

MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
MODULE_DESCRIPTION("HID driver for VRC-2 2-axis Car controller");
MODULE_LICENSE("GPL");