1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  HID driver for ELECOM devices:
4 *  - BM084 Bluetooth Mouse
5 *  - EX-G Trackballs (M-XT3DRBK, M-XT3URBK, M-XT4DRBK)
6 *  - DEFT Trackballs (M-DT1DRBK, M-DT1URBK, M-DT2DRBK, M-DT2URBK)
7 *  - HUGE Trackballs (M-HT1DRBK, M-HT1URBK)
8 *
9 *  Copyright (c) 2010 Richard Nauber <Richard.Nauber@gmail.com>
10 *  Copyright (c) 2016 Yuxuan Shui <yshuiv7@gmail.com>
11 *  Copyright (c) 2017 Diego Elio Pettenò <flameeyes@flameeyes.eu>
12 *  Copyright (c) 2017 Alex Manoussakis <amanou@gnu.org>
13 *  Copyright (c) 2017 Tomasz Kramkowski <tk@the-tk.com>
14 */
15
16/*
17 */
18
19#include <linux/device.h>
20#include <linux/hid.h>
21#include <linux/module.h>
22
23#include "hid-ids.h"
24
25/*
26 * Certain ELECOM mice misreport their button count meaning that they only work
27 * correctly with the ELECOM mouse assistant software which is unavailable for
28 * Linux. A four extra INPUT reports and a FEATURE report are described by the
29 * report descriptor but it does not appear that these enable software to
30 * control what the extra buttons map to. The only simple and straightforward
31 * solution seems to involve fixing up the report descriptor.
32 *
33 * Report descriptor format:
34 * Positions 13, 15, 21 and 31 store the button bit count, button usage minimum,
35 * button usage maximum and padding bit count respectively.
36 */
37#define MOUSE_BUTTONS_MAX 8
38static void mouse_button_fixup(struct hid_device *hdev,
39			       __u8 *rdesc, unsigned int rsize,
40			       int nbuttons)
41{
42	if (rsize < 32 || rdesc[12] != 0x95 ||
43	    rdesc[14] != 0x75 || rdesc[15] != 0x01 ||
44	    rdesc[20] != 0x29 || rdesc[30] != 0x75)
45		return;
46	hid_info(hdev, "Fixing up Elecom mouse button count\n");
47	nbuttons = clamp(nbuttons, 0, MOUSE_BUTTONS_MAX);
48	rdesc[13] = nbuttons;
49	rdesc[21] = nbuttons;
50	rdesc[31] = MOUSE_BUTTONS_MAX - nbuttons;
51}
52
53static __u8 *elecom_report_fixup(struct hid_device *hdev, __u8 *rdesc,
54		unsigned int *rsize)
55{
56	switch (hdev->product) {
57	case USB_DEVICE_ID_ELECOM_BM084:
58		/* The BM084 Bluetooth mouse includes a non-existing horizontal
59		 * wheel in the HID descriptor. */
60		if (*rsize >= 48 && rdesc[46] == 0x05 && rdesc[47] == 0x0c) {
61			hid_info(hdev, "Fixing up Elecom BM084 report descriptor\n");
62			rdesc[47] = 0x00;
63		}
64		break;
65	case USB_DEVICE_ID_ELECOM_M_XT3URBK:
66	case USB_DEVICE_ID_ELECOM_M_XT3DRBK:
67	case USB_DEVICE_ID_ELECOM_M_XT4DRBK:
68		mouse_button_fixup(hdev, rdesc, *rsize, 6);
69		break;
70	case USB_DEVICE_ID_ELECOM_M_DT1URBK:
71	case USB_DEVICE_ID_ELECOM_M_DT1DRBK:
72	case USB_DEVICE_ID_ELECOM_M_HT1URBK:
73	case USB_DEVICE_ID_ELECOM_M_HT1DRBK:
74		mouse_button_fixup(hdev, rdesc, *rsize, 8);
75		break;
76	}
77	return rdesc;
78}
79
80static const struct hid_device_id elecom_devices[] = {
81	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
82	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK) },
83	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK) },
84	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },
85	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
86	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
87	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1URBK) },
88	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK) },
89	{ }
90};
91MODULE_DEVICE_TABLE(hid, elecom_devices);
92
93static struct hid_driver elecom_driver = {
94	.name = "elecom",
95	.id_table = elecom_devices,
96	.report_fixup = elecom_report_fixup
97};
98module_hid_driver(elecom_driver);
99
100MODULE_LICENSE("GPL");
101