src/include/gpxe/nvs.h

   1 #ifndef _GPXE_NVS_H
   2 #define _GPXE_NVS_H
   3
   4 /** @file
   5  *
   6  * Non-volatile storage
   7  *
   8  */
   9
  10 FILE_LICENCE ( GPL2_OR_LATER );
  11
  12 #include <stdint.h>
  13
  14 /** A non-volatile storage device */
  15 struct nvs_device {
  16         /** Word length
  17          *
  18          * This is expressed as the base-2 logarithm of the word
  19          * length in bytes.  A value of 0 therefore translates as
  20          * 8-bit words, and a value of 1 translates as 16-bit words.
  21          */
  22         unsigned int word_len_log2;
  23         /** Device size (in words) */
  24         unsigned int size;
  25         /** Data block size (in words)
  26          *
  27          * This is the block size used by the device.  It must be a
  28          * power of two.  Data reads and writes must not cross a block
  29          * boundary.
  30          *
  31          * Many devices allow reads to cross a block boundary, and
  32          * restrict only writes.  For the sake of simplicity, we
  33          * assume that the same restriction applies to both reads and
  34          * writes.
  35          */
  36         unsigned int block_size;
  37         /** Read data from device
  38          *
  39          * @v nvs               NVS device
  40          * @v address           Address from which to read
  41          * @v data              Data buffer
  42          * @v len               Length of data buffer
  43          * @ret rc              Return status code
  44          *
  45          * Reads may not cross a block boundary.
  46          */
  47         int ( * read ) ( struct nvs_device *nvs, unsigned int address,
  48                          void *data, size_t len );
  49         /** Write data to device
  50          *
  51          * @v nvs               NVS device
  52          * @v address           Address to which to write
  53          * @v data              Data buffer
  54          * @v len               Length of data buffer
  55          * @ret rc              Return status code
  56          *
  57          * Writes may not cross a block boundary.
  58          */
  59         int ( * write ) ( struct nvs_device *nvs, unsigned int address,
  60                           const void *data, size_t len );
  61 };
  62
  63 extern int nvs_read ( struct nvs_device *nvs, unsigned int address,
  64                       void *data, size_t len );
  65 extern int nvs_write ( struct nvs_device *nvs, unsigned int address,
  66                        const void *data, size_t len );
  67
  68 #endif /* _GPXE_NVS_H */