source: trunk/kernel/vfs/fatfs.h @ 1

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1/*
2 * fatfs.h - FATFS file system API definition.
3 *
4 * Author    Mohamed Lamine Karaoui (2015)
5 *           Alain Greiner (2016)
6 *
7 * Copyright (c) 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 _FATFS_H_
26#define _FATFS_H_
27
28#include <hal_types.h>
29#include <rwlock.h>
30
31/****  Forward declarations  ****/
32
33struct mapper_s;
34struct device_s;
35struct vfs_inode_s;
36struct vfs_ctx_s;
37struct page_s;
38
39/*****************************************************************************************
40 * This structure defines a FATFS specific context extension.
41 ****************************************************************************************/
42
43typedef struct fatfs_ctx_s
44{
45    rwlock_t          lock;                  /*! TODO protect what ???                  */
46    uint32_t          fat_begin_lba;         /*! first lba of FAT region                */
47    uint32_t          fat_sectors_count;     /*! number of sectors in FAT region        */
48    uint32_t          bytes_per_sector;      /*!                                        */
49    uint32_t          bytes_per_cluster;     /*!                                        */
50    uint32_t          cluster_begin_lba;     /*! first lba of data region on device     */
51    uint32_t          sectors_per_cluster;   /*!                                        */
52    uint32_t          rootdir_first_cluster; /*                                         */
53    uint32_t          last_allocated_sector; /*!                                        */
54    uint32_t          last_allocated_index;  /*! TODO last allocated cluster ???        */
55    xptr_t            fat_mapper_xp;         /*! FAT mapper (in IO cluster)             */ 
56}
57fatfs_ctx_t;
58
59/*****************************************************************************************
60 * This structure defines the FAT specific inode extension (versus the VFS inode).
61 ****************************************************************************************/
62
63typedef struct fatfs_inode_s
64{
65    struct fatfs_ctx_s * ctx;                /*! local pointer on the FATFS context     */ 
66        uint32_t             first_cluster;      /*! first cluster for this file/dir        */ 
67}
68fatfs_inode_t;
69
70
71
72/*****************************************************************************************
73 * This function returns the LBA of the first sector of a FAT cluster.
74 * This function can be called by any thread running in any cluster.
75 *****************************************************************************************
76 * @ ctx          :     pointer on FATFS context.
77 * @ cluster  : cluster index in FATFS.
78 * # return the lba value.
79 ****************************************************************************************/
80inline uint32_t fatfs_lba_from_cluster( fatfs_ctx_t * ctx,
81                                        uint32_t      cluster );
82
83/*****************************************************************************************
84 * This function scan the FAT (File Allocation Table), stored in the FAT mapper,
85 * and return the FATFS cluster index for a given page of a given file.
86 * It must be called by a thread running in the cluster containing the FAT mapper
87 * (can be a local thread or a RPC thread).
88 * The FAT is actually an array of uint32_t slots. Each slot in this array contains the
89 * index of another slot in this array, to form one linked list for each file stored on
90 * device in the RAMFS file system. This index in the FAT array is also the index of the
91 * FATFS cluster on the device. One FATFS cluster is supposed to contain one PPM page.
92 * For a given file, the entry point in the FAT is simply the index of the FATFS cluster
93 * containing the first page of the file. The mapper being a cache, this function
94 * automatically updates the FAT mapper from informations stored on device in case of miss.
95 *****************************************************************************************
96 * @ mapper      : local pointer on the FAT mapper.
97 * @ first       : index of the first FATFS cluster allocated to the file.
98 * @ page    : index of searched page in the file.
99 * @ cluster : [out] pointer on buffer for the found FATFS cluster index.
100 * @ return 0 if success / return EIO if FAT mapper miss cannot be solved.
101 ****************************************************************************************/
102error_t fatfs_get_cluster( struct mapper_s * mapper,
103                           uint32_t          first_cluster,
104                           uint32_t          searched_page,
105                           uint32_t        * cluster );
106
107/*****************************************************************************************
108 * This function allocates memory for a FATFS inode, initializes it,
109 * and link it to the VFS inode.
110 *****************************************************************************************
111 * @ inode   : local pointer on vfs_inode.
112 * @ return 0 if success / return ENOMEM if error.
113 ****************************************************************************************/
114error_t fatfs_inode_create( struct vfs_inode_s * inode );
115
116/*****************************************************************************************
117 * This function releases memory allocated for a FATFS inode.
118 *****************************************************************************************
119 * @ inode   : local pointer on vfs_inode.
120 ****************************************************************************************/
121void fatfs_inode_destroy( struct vfs_inode_s * inode );
122
123/*****************************************************************************************
124 * This function allocates memory for a FATFS context, initialises it,
125 * and link it to the local VFS context.
126 *****************************************************************************************
127 * @ inode   : local pointer on VFS context.
128 * @ return 0 if success / return ENOMEM if error.
129 ****************************************************************************************/
130error_t fatfs_ctx_create( struct vfs_ctx_s * ctx );
131
132/*****************************************************************************************
133 * This function releases memory allocated for a FATFS context.
134 *****************************************************************************************
135 * @ ctx   : local pointer on VFS context.
136 ****************************************************************************************/
137void fatfs_ctx_destroy( struct vfs_ctx_s * ctx );
138
139/*****************************************************************************************
140 * This function moves a page from the mapper to the FATFS file system.
141 * It must be called by a thread running in cluster containing the mapper.
142 * The pointer on the mapper and the page index in file are supposed to be registered
143 * in the page descriptor.
144 *****************************************************************************************
145 * @ page    : local pointer on page descriptor.
146 * @ return 0 if success / return EIO if error.
147 ****************************************************************************************/
148error_t fatfs_write_page( struct page_s * page );
149
150/*****************************************************************************************
151 * This function moves a page from the FATFS file system on device to the mapper.
152 * It must be called by a thread running in cluster containing the mapper.
153 * The pointer on the mapper and the page index in file are supposed to be registered
154 * in the page descriptor.
155 *****************************************************************************************
156 * @ page    : local pointer on page descriptor.
157 * @ return 0 if success / return EIO if error.
158 ****************************************************************************************/
159error_t fatfs_read_page( struct page_s * page );
160
161
162#endif  /* _FATFS_H_ */
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