xref: /onnv-gate/usr/src/uts/common/sys/open.h (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
23*0Sstevel@tonic-gate /*	  All Rights Reserved  	*/
24*0Sstevel@tonic-gate 
25*0Sstevel@tonic-gate 
26*0Sstevel@tonic-gate #ifndef _SYS_OPEN_H
27*0Sstevel@tonic-gate #define	_SYS_OPEN_H
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"	/* from SVR4 11.4 */
30*0Sstevel@tonic-gate 
31*0Sstevel@tonic-gate #ifdef	__cplusplus
32*0Sstevel@tonic-gate extern "C" {
33*0Sstevel@tonic-gate #endif
34*0Sstevel@tonic-gate 
35*0Sstevel@tonic-gate /*
36*0Sstevel@tonic-gate  * Some drivers need to be able to keep accurate records of open/close
37*0Sstevel@tonic-gate  * calls to determine whether a device is still in use.  To allow this
38*0Sstevel@tonic-gate  * open/close calls have been typed and the type is passed as a third
39*0Sstevel@tonic-gate  * argument in open/close calls, as in:
40*0Sstevel@tonic-gate  *	(*cdevsw[getmajor(dev)].d_open)(getminor(dev), flag, OTYP_CHR);
41*0Sstevel@tonic-gate  * or
42*0Sstevel@tonic-gate  *	(*cdevsw[getmajor(dev)].d_close)(getminor(dev), flag, OTYP_CHR);
43*0Sstevel@tonic-gate  * Five types of open/close calls have been defined:
44*0Sstevel@tonic-gate  * OTYP_BLK:	open/close of a block special file
45*0Sstevel@tonic-gate  * OTYP_MNT:	open/close for mounting/unmounting a file system
46*0Sstevel@tonic-gate  * OTYP_CHR:	open/close of a character special file
47*0Sstevel@tonic-gate  * OTYP_SWP:	open/close of a swapping device.
48*0Sstevel@tonic-gate  * OTYP_LYR:	open/close calls from a driver to another driver,
49*0Sstevel@tonic-gate  *		without a file being open for the dev of the lower driver.
50*0Sstevel@tonic-gate  *
51*0Sstevel@tonic-gate  * The first four types of open/close calls obey the protocol rule
52*0Sstevel@tonic-gate  * that many more opens may occur for a given minor(dev) for that type of open,
53*0Sstevel@tonic-gate  * but a close call happens only on the last close of that dev.
54*0Sstevel@tonic-gate  * This protocol allows a flag to be used (set by opens, cleared by closes)
55*0Sstevel@tonic-gate  * to keep track of the state for a given minor device value.
56*0Sstevel@tonic-gate  *
57*0Sstevel@tonic-gate  * Calls of the fifth type (OTYP_LYR) must obey the protocol rule
58*0Sstevel@tonic-gate  * that open and close call calls are always paired.  This protocol
59*0Sstevel@tonic-gate  * permits several drivers to be layers above the same device driver.
60*0Sstevel@tonic-gate  * A counter can be used for this protocol.
61*0Sstevel@tonic-gate  *
62*0Sstevel@tonic-gate  * The value OTYPCNT is defined for the purpose of declaring arrays
63*0Sstevel@tonic-gate  * in drivers and for performing range checks (0 <= otyp < OTYPCNT)
64*0Sstevel@tonic-gate  * on values passed.
65*0Sstevel@tonic-gate  */
66*0Sstevel@tonic-gate 
67*0Sstevel@tonic-gate #define	OTYPCNT		5
68*0Sstevel@tonic-gate #define	OTYP_BLK	0
69*0Sstevel@tonic-gate #define	OTYP_MNT	1
70*0Sstevel@tonic-gate #define	OTYP_CHR	2
71*0Sstevel@tonic-gate #define	OTYP_SWP	3
72*0Sstevel@tonic-gate #define	OTYP_LYR	4
73*0Sstevel@tonic-gate 
74*0Sstevel@tonic-gate #ifdef	__cplusplus
75*0Sstevel@tonic-gate }
76*0Sstevel@tonic-gate #endif
77*0Sstevel@tonic-gate 
78*0Sstevel@tonic-gate #endif	/* _SYS_OPEN_H */
79