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 *  Copyright (c) 2020 YOSHIOKA Takuma <lo48576@hard-wi.red>
15 *  Copyright (c) 2022 Takahiro Fujii <fujii@xaxxi.net>
16 */
17
18/*
19 */
20
21#include <linux/device.h>
22#include <linux/hid.h>
23#include <linux/module.h>
24
25#include "hid-ids.h"
26
27/*
28 * Certain ELECOM mice misreport their button count meaning that they only work
29 * correctly with the ELECOM mouse assistant software which is unavailable for
30 * Linux. A four extra INPUT reports and a FEATURE report are described by the
31 * report descriptor but it does not appear that these enable software to
32 * control what the extra buttons map to. The only simple and straightforward
33 * solution seems to involve fixing up the report descriptor.
34 */
35#define MOUSE_BUTTONS_MAX 8
36static void mouse_button_fixup(struct hid_device *hdev,
37			       __u8 *rdesc, unsigned int rsize,
38			       unsigned int button_bit_count,
39			       unsigned int padding_bit,
40			       unsigned int button_report_size,
41			       unsigned int button_usage_maximum,
42			       int nbuttons)
43{
44	if (rsize < 32 || rdesc[button_bit_count] != 0x95 ||
45	    rdesc[button_report_size] != 0x75 ||
46	    rdesc[button_report_size + 1] != 0x01 ||
47	    rdesc[button_usage_maximum] != 0x29 || rdesc[padding_bit] != 0x75)
48		return;
49	hid_info(hdev, "Fixing up Elecom mouse button count\n");
50	nbuttons = clamp(nbuttons, 0, MOUSE_BUTTONS_MAX);
51	rdesc[button_bit_count + 1] = nbuttons;
52	rdesc[button_usage_maximum + 1] = nbuttons;
53	rdesc[padding_bit + 1] = MOUSE_BUTTONS_MAX - nbuttons;
54}
55
56static __u8 *elecom_report_fixup(struct hid_device *hdev, __u8 *rdesc,
57		unsigned int *rsize)
58{
59	switch (hdev->product) {
60	case USB_DEVICE_ID_ELECOM_BM084:
61		/* The BM084 Bluetooth mouse includes a non-existing horizontal
62		 * wheel in the HID descriptor. */
63		if (*rsize >= 48 && rdesc[46] == 0x05 && rdesc[47] == 0x0c) {
64			hid_info(hdev, "Fixing up Elecom BM084 report descriptor\n");
65			rdesc[47] = 0x00;
66		}
67		break;
68	case USB_DEVICE_ID_ELECOM_M_XGL20DLBK:
69		/*
70		 * Report descriptor format:
71		 * 20: button bit count
72		 * 28: padding bit count
73		 * 22: button report size
74		 * 14: button usage maximum
75		 */
76		mouse_button_fixup(hdev, rdesc, *rsize, 20, 28, 22, 14, 8);
77		break;
78	case USB_DEVICE_ID_ELECOM_M_XT3URBK:
79	case USB_DEVICE_ID_ELECOM_M_XT3DRBK:
80	case USB_DEVICE_ID_ELECOM_M_XT4DRBK:
81		/*
82		 * Report descriptor format:
83		 * 12: button bit count
84		 * 30: padding bit count
85		 * 14: button report size
86		 * 20: button usage maximum
87		 */
88		mouse_button_fixup(hdev, rdesc, *rsize, 12, 30, 14, 20, 6);
89		break;
90	case USB_DEVICE_ID_ELECOM_M_DT1URBK:
91	case USB_DEVICE_ID_ELECOM_M_DT1DRBK:
92	case USB_DEVICE_ID_ELECOM_M_HT1URBK:
93	case USB_DEVICE_ID_ELECOM_M_HT1DRBK_010D:
94		/*
95		 * Report descriptor format:
96		 * 12: button bit count
97		 * 30: padding bit count
98		 * 14: button report size
99		 * 20: button usage maximum
100		 */
101		mouse_button_fixup(hdev, rdesc, *rsize, 12, 30, 14, 20, 8);
102		break;
103	case USB_DEVICE_ID_ELECOM_M_HT1DRBK_011C:
104		/*
105		 * Report descriptor format:
106		 * 22: button bit count
107		 * 30: padding bit count
108		 * 24: button report size
109		 * 16: button usage maximum
110		 */
111		mouse_button_fixup(hdev, rdesc, *rsize, 22, 30, 24, 16, 8);
112		break;
113	}
114	return rdesc;
115}
116
117static const struct hid_device_id elecom_devices[] = {
118	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_BM084) },
119	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XGL20DLBK) },
120	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3URBK) },
121	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT3DRBK) },
122	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_XT4DRBK) },
123	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1URBK) },
124	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_DT1DRBK) },
125	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1URBK) },
126	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK_010D) },
127	{ HID_USB_DEVICE(USB_VENDOR_ID_ELECOM, USB_DEVICE_ID_ELECOM_M_HT1DRBK_011C) },
128	{ }
129};
130MODULE_DEVICE_TABLE(hid, elecom_devices);
131
132static struct hid_driver elecom_driver = {
133	.name = "elecom",
134	.id_table = elecom_devices,
135	.report_fixup = elecom_report_fixup
136};
137module_hid_driver(elecom_driver);
138
139MODULE_LICENSE("GPL");
140