open.h revision 7c478bd95313f5f23a4c958a745db2134aa03244
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License, Version 1.0 only
* (the "License"). You may not use this file except in compliance
* with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/* Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/* All Rights Reserved */
#ifndef _SYS_OPEN_H
#define _SYS_OPEN_H
#pragma ident "%Z%%M% %I% %E% SMI" /* from SVR4 11.4 */
#ifdef __cplusplus
extern "C" {
#endif
/*
* Some drivers need to be able to keep accurate records of open/close
* calls to determine whether a device is still in use. To allow this
* open/close calls have been typed and the type is passed as a third
* argument in open/close calls, as in:
* (*cdevsw[getmajor(dev)].d_open)(getminor(dev), flag, OTYP_CHR);
* or
* (*cdevsw[getmajor(dev)].d_close)(getminor(dev), flag, OTYP_CHR);
* Five types of open/close calls have been defined:
* OTYP_BLK: open/close of a block special file
* OTYP_MNT: open/close for mounting/unmounting a file system
* OTYP_CHR: open/close of a character special file
* OTYP_SWP: open/close of a swapping device.
* OTYP_LYR: open/close calls from a driver to another driver,
* without a file being open for the dev of the lower driver.
*
* The first four types of open/close calls obey the protocol rule
* that many more opens may occur for a given minor(dev) for that type of open,
* but a close call happens only on the last close of that dev.
* This protocol allows a flag to be used (set by opens, cleared by closes)
* to keep track of the state for a given minor device value.
*
* Calls of the fifth type (OTYP_LYR) must obey the protocol rule
* that open and close call calls are always paired. This protocol
* permits several drivers to be layers above the same device driver.
* A counter can be used for this protocol.
*
* The value OTYPCNT is defined for the purpose of declaring arrays
* in drivers and for performing range checks (0 <= otyp < OTYPCNT)
* on values passed.
*/
#define OTYPCNT 5
#define OTYP_BLK 0
#define OTYP_MNT 1
#define OTYP_CHR 2
#define OTYP_SWP 3
#define OTYP_LYR 4
#ifdef __cplusplus
}
#endif
#endif /* _SYS_OPEN_H */