The C and C++ Include Header Files

/usr/include/linux/userio.h


$ cat -n /usr/include/linux/userio.h

     1	/* SPDX-License-Identifier: LGPL-2.0+ WITH Linux-syscall-note */
     2	/*
     3	 * userio: virtual serio device support
     4	 * Copyright (C) 2015 Red Hat
     5	 * Copyright (C) 2015 Lyude (Stephen Chandler Paul) <cpaul@redhat.com>
     6	 *
     7	 * This program is free software; you can redistribute it and/or modify it
     8	 * under the terms of the GNU Lesser General Public License as published by the
     9	 * Free Software Foundation; either version 2 of the License, or (at your
    10	 * option) any later version.
    11	 *
    12	 * This program is distributed in the hope that it will be useful, but WITHOUT
    13	 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    14	 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
    15	 * details.
    16	 *
    17	 * This is the public header used for user-space communication with the userio
    18	 * driver. __attribute__((__packed__)) is used for all structs to keep ABI
    19	 * compatibility between all architectures.
    20	 */
    21	
    22	#ifndef _USERIO_H
    23	#define _USERIO_H
    24	
    25	#include <linux/types.h>
    26	
    27	enum userio_cmd_type {
    28		USERIO_CMD_REGISTER = 0,
    29		USERIO_CMD_SET_PORT_TYPE = 1,
    30		USERIO_CMD_SEND_INTERRUPT = 2
    31	};
    32	
    33	/*
    34	 * userio Commands
    35	 * All commands sent to /dev/userio are encoded using this structure. The type
    36	 * field should contain a USERIO_CMD* value that indicates what kind of command
    37	 * is being sent to userio. The data field should contain the accompanying
    38	 * argument for the command, if there is one.
    39	 */
    40	struct userio_cmd {
    41		__u8 type;
    42		__u8 data;
    43	} __attribute__((__packed__));
    44	
    45	#endif /* !_USERIO_H */