source: trunk/kernel/vfs/devfs.h @ 76

Last change on this file since 76 was 23, checked in by alain, 7 years ago

Introduce syscalls.
File size: 7.0 KB
Line 
1/*
2 * devfs.h - DEVFS File System API definition                               
3 *
4 * Authors       Mohamed Lamine Karaoui (2014,2015)
5 *               Alain Greiner (2016,2017)
6 *
7 * Copyright (c) 2011,2012 UPMC Sorbonne Universites
8 *
9 * This file is part of ALMOS-MKH.
10 *
11 * ALMOS-MKH is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; version 2.0 of the License.
14 *
15 * ALMOS-MKH is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with ALMOS-MKH; if not, write to the Free Software Foundation,
22 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
23 */
24
25#ifndef _DEVFS_H_
26#define _DEVFS_H_
27
28///////////////////////////////////////////////////////////////////////////////////////////
29// The DEVFS File System contains inodes associated to all chdev descriptors availables
30// in the target architecture.  It is a three levels tree structure:
31// - The "dev" directory inode is stored in cluster_0. It is the root of the devfs
32//   file system. The parent inode is the "/" global root.
33// - There is one "internal_cxy" directory inode per cluster, that is the parent of
34//   the local children inodes associated to the local chdev descriptors.
35//   The parent inode and dentry are stored in cluster_0.
36// - The I/O cluster contains one "external" directory inode, that is the parent of
37//   the remote children inodes associated to the remote external descriptors.
38//   The parent inode and dentry are stored in cluster_0.
39//
40// The DEVFS File system does not require a context extension, but requires an inode
41// extension to store the pointer on the associated chdev descriptor.
42///////////////////////////////////////////////////////////////////////////////////////////
43
44/**************  Forward declarations     ************************************************/
45
46struct chdev_s;
47
48/******************************************************************************************
49 * This structure defines the DEVFS inode descriptor extension.
50 *****************************************************************************************/
51
52typedef struct devfs_inode_ext_s
53{
54    struct chdev_s * chdev;       /* extended pointer on associated chdev                */
55}
56devfs_inode_t;
57
58
59
60
61
62//////////////////////////////////////////////////////////////////////////////////////////
63//                 These functions are called by the VFS.
64//////////////////////////////////////////////////////////////////////////////////////////
65
66/******************************************************************************************
67 * This function  does not exist for the DEVFS file system, as this File System
68 * cannot be mounted as the root FS.
69 *****************************************************************************************/
70xptr_t devfs_init();
71
72
73/******************************************************************************************
74 * This function mount the DEVFS file system on the root FS.
75 * It is executed cooperatively during kernel init by all CP0s in all clusters,
76 * to create the DEVFS 3-levels tree structure.
77 * This is a four phases procedure, and it uses the global barrier to synchronize
78 * the cooperating kernel instances when required.
79 * - phase 1 : In all clusters, it creates the local extension of the DEVFS context,
80 *    and initialises it.
81 * - phase 2 : In cluster_0 only, it creates the dentry and the associated inode for
82 *   the DEVFS root directory.
83 * - phase 3 : In all cluster(x,y), it creates the dentry and the associated inode for
84 *   the "internal_cxy" directory. It also creates the dentry and associated inode
85 *   for all local internal chdevs.
86 * - phase 4 : In cluster_io only, it creates the dentry and the associated inode
87 *   for the "external" directory. It also creates the dentry and associated inode
88 *   for all external chdevs.
89 ******************************************************************************************
90 * @ parent_inode_xp   : extended pointer on the parent inode in root FS.
91 * @ devfs_root_name   : DEVFS root directory name.
92 *****************************************************************************************/
93error_t devfs_mount( xptr_t   parent_inode_xp,
94                     char   * devfs_root_name );
95
96/*****************************************************************************************
97 * This function initializes all fields of the VFS context.
98 * No extra memory is allocated for a DEVFS context.
99 *****************************************************************************************
100 * @ vfs_ctx        : local pointer on VFS context for FATFS.
101 * @ root_inode_xp  : extended pointer on the VFS root inode.
102 ****************************************************************************************/
103error_t devfs_ctx_init( struct vfs_ctx_s * vfs_ctx,
104                        xptr_t             root_inode_xp );
105
106/*****************************************************************************************
107 * This function does not exist for a DEVFS context, as there is no DEVFS context.
108 ****************************************************************************************/
109error_t devfs_ctx_destroy();
110
111/*****************************************************************************************
112 * This function allocates memory for a DEVFS inode, initialise it,
113 * and link it to the VFS inode.
114 *****************************************************************************************
115 * @ inode          : local pointer on the VFS inode.
116 * @ chdev          : local pointer on the chdev to be inserted in DEVFS.
117 ****************************************************************************************/
118error_t devfs_inode_create( struct vfs_inode_s * inode,
119                            struct chdev_s     * chdev );
120
121/*****************************************************************************************
122 * This function releases memory allocated for a DEVFS inode.
123 *****************************************************************************************
124 * @ inode   : local pointer on vfs_inode.
125 ****************************************************************************************/
126void devfs_inode_destroy( struct vfs_inode_s * inode );
127
128/*****************************************************************************************
129 * This function does not exist for the DEVFS File System.
130 ****************************************************************************************/
131error_t devfs_write_page( struct page_s * page );
132
133/*****************************************************************************************
134 * This function does not exist for the DEVFS File System.
135 ****************************************************************************************/
136error_t devfs_read_page( struct page_s * page );
137
138
139
140#endif  /* _DEVFS_H_ */
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