HID: bpf: add in-tree HID-BPF fix for the IOGear Kaliber Gaming MMOmentum mouse

Allows to export more than 5 buttons on this 12 buttons mouse.

Link: https://lore.kernel.org/r/20240410-bpf_sources-v1-5-a8bf16033ef8@kernel.orgReviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>

drivers/hid/bpf/progs/IOGEAR__Kaliber-MMOmentum.bpf.c

+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2023 Benjamin Tissoires
+ */
+
+#include "vmlinux.h"
+#include "hid_bpf.h"
+#include "hid_bpf_helpers.h"
+#include <bpf/bpf_tracing.h>
+
+#define VID_IOGEAR 0x258A /* VID is shared with SinoWealth and Glorious and prob others */
+#define PID_MOMENTUM 0x0027
+
+HID_BPF_CONFIG(
+	HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, VID_IOGEAR, PID_MOMENTUM)
+);
+
+/*
+ * The IOGear Kaliber Gaming MMOmentum Pro mouse has multiple buttons (12)
+ * but only 5 are accessible out of the box because the report descriptor
+ * marks the other buttons as constants.
+ * We just fix the report descriptor to enable those missing 7 buttons.
+ */
+
+SEC("fmod_ret/hid_bpf_rdesc_fixup")
+int BPF_PROG(hid_fix_rdesc, struct hid_bpf_ctx *hctx)
+{
+	const u8 offsets[] = {84, 112, 140};
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 4096 /* size */);
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	/* if not Keyboard */
+	if (data[3] != 0x06)
+		return 0;
+
+	for (int idx = 0; idx < ARRAY_SIZE(offsets); idx++) {
+		u8 offset = offsets[idx];
+
+		/* if Input (Cnst,Var,Abs) , make it Input (Data,Var,Abs) */
+		if (data[offset] == 0x81 && data[offset + 1] == 0x03)
+			data[offset + 1] = 0x02;
+	}
+
+	return 0;
+}
+
+SEC("syscall")
+int probe(struct hid_bpf_probe_args *ctx)
+{
+	/* only bind to the keyboard interface */
+	ctx->retval = ctx->rdesc_size != 213;
+	if (ctx->retval)
+		ctx->retval = -EINVAL;
+
+	return 0;
+}
+
+char _license[] SEC("license") = "GPL";