src/include/region_file.h

   1 /*
   2  * This file is part of the coreboot project.
   3  *
   4  * Copyright 2016 Google Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; version 2 of the License.
   9  *
  10  * This program is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  * GNU General Public License for more details.
  14  */
  15
  16 #ifndef REGION_FILE_H
  17 #define REGION_FILE_H
  18
  19 #include <commonlib/region.h>
  20 #include <stdint.h>
  21
  22 /*
  23  * A region file is an abstraction to allow appending updates in a
  24  * region_device where the data returned is the most recently written
  25  * data. It is block based with a 16 byte granularity. So if you write
  26  * 2 bytes into the file the data returned in the region_device would
  27  * have 16 bytes allocated for the latest update. Additionally, the
  28  * current maximum file size allowed is 1MiB - 48 bytes. See comments
  29  * in C implementation file for further details.
  30  */
  31
  32 struct region_file;
  33
  34 /*
  35  * Initialize a region file associated with a provided region device.
  36  * Returns < 0 on error, 0 on success.
  37  */
  38 int region_file_init(struct region_file *f, const struct region_device *p);
  39
  40 /*
  41  * Initialize region device object associated with latest update of file data.
  42  * Returns < 0 on error, 0 on success.
  43  */
  44 int region_file_data(const struct region_file *f, struct region_device *rdev);
  45
  46 /* Update region file with latest data. Returns < 0 on error, 0 on success. */
  47 int region_file_update_data(struct region_file *f, const void *buf,
  48                                 size_t size);
  49
  50 /* Declared here for easy object allocation. */
  51 struct region_file {
  52         /* Region device covering file */
  53         struct region_device rdev;
  54         /* Metadata containing blocks of the data stream. */
  55         struct region_device metadata;
  56         /* Blocks forming data. */
  57         uint16_t data_blocks[2];
  58         /* Current slot in metadata marking end of data. */
  59         int slot;
  60 };
  61
  62 #endif /* REGION_FILE_H */