// SPDX-License-Identifier: GPL-2.0-or-later
/* Copyright (c) 2025 TUXEDO Computers GmbH
 */

#include "vmlinux.h"
#include "hid_bpf.h"
#include "hid_bpf_helpers.h"
#include <bpf/bpf_tracing.h>

HID_BPF_CONFIG(
        HID_DEVICE(BUS_USB, HID_GROUP_GENERIC, 0x048D, 0x8910)
);

SEC(HID_BPF_DEVICE_EVENT)
int BPF_PROG(ignore_key_fix_event, struct hid_bpf_ctx *hid_ctx)
{
        const int expected_length = 37;
        const int expected_report_id = 1;
        __u8 *data;
        int i;

        if (hid_ctx->size < expected_length)
                return 0;

        data = hid_bpf_get_data(hid_ctx, 0, expected_length);
        if (!data || data[0] != expected_report_id)
                return 0;

        // Zero out F13 (HID usage ID: 0x68) key press.
        // The first 6 parallel key presses (excluding modifier keys) are
        // encoded in an array containing usage IDs.
        for (i = 3; i < 9; ++i)
                if (data[i] == 0x68)
                        data[i] = 0x00;
        // Additional parallel key presses starting with the 7th (excluding
        // modifier keys) are encoded as a bit flag with the offset being
        // the usage ID.
        data[22] &= 0xfe;

        return 0;
}

HID_BPF_OPS(ignore_button) = {
        .hid_device_event = (void *)ignore_key_fix_event,
};

char _license[] SEC("license") = "GPL";