IOGEAR__Kaliber-MMOmentum.bpf.c

 1// SPDX-License-Identifier: GPL-2.0-only
 2/* Copyright (c) 2023 Benjamin Tissoires
 3 */
 4
 5#include "vmlinux.h"
 6#include "hid_bpf.h"
 7#include "hid_bpf_helpers.h"
 8#include <bpf/bpf_tracing.h>
 9
10#define VID_IOGEAR 0x258A /* VID is shared with SinoWealth and Glorious and prob others */
11#define PID_MOMENTUM 0x0027
12
13HID_BPF_CONFIG(
14	HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_IOGEAR, PID_MOMENTUM)
15);
16
17/*
18 * The IOGear Kaliber Gaming MMOmentum Pro mouse has multiple buttons (12)
19 * but only 5 are accessible out of the box because the report descriptor
20 * marks the other buttons as constants.
21 * We just fix the report descriptor to enable those missing 7 buttons.
22 */
23
24SEC(HID_BPF_RDESC_FIXUP)
25int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
26{
27	const u8 offsets[] = {84, 112, 140};
28	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
29
30	if (!data)
31		return 0; /* EPERM check */
32
33	/* if not Keyboard */
34	if (data[3] != 0x06)
35		return 0;
36
37	for (int idx = 0; idx < ARRAY_SIZE(offsets); idx++) {
38		u8 offset = offsets[idx];
39
40		/* if Input (Cnst,Var,Abs) , make it Input (Data,Var,Abs) */
41		if (data[offset] == 0x81 && data[offset + 1] == 0x03)
42			data[offset + 1] = 0x02;
43	}
44
45	return 0;
46}
47
48HID_BPF_OPS(iogear_kaliber_momentum) = {
49	.hid_rdesc_fixup = (void *)hid_fix_rdesc,
50};
51
52SEC("syscall")
53int probe(struct hid_bpf_probe_args *ctx)
54{
55	/* only bind to the keyboard interface */
56	ctx->retval = ctx->rdesc_size != 213;
57	if (ctx->retval)
58		ctx->retval = -EINVAL;
59
60	return 0;
61}
62
63char _license[] SEC("license") = "GPL";