nvs.h

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#ifndef _GPXE_NVS_H
#define _GPXE_NVS_H

/** @file
 *
 * Non-volatile storage
 *
 */

FILE_LICENCE ( GPL2_OR_LATER );

#include <stdint.h>

/** A non-volatile storage device */
struct nvs_device {
        /** Word length
         *
         * This is expressed as the base-2 logarithm of the word
         * length in bytes.  A value of 0 therefore translates as
         * 8-bit words, and a value of 1 translates as 16-bit words.
         */
        unsigned int word_len_log2;
        /** Device size (in words) */
        unsigned int size;
        /** Data block size (in words)
         *
         * This is the block size used by the device.  It must be a
         * power of two.  Data reads and writes must not cross a block
         * boundary.
         *
         * Many devices allow reads to cross a block boundary, and
         * restrict only writes.  For the sake of simplicity, we
         * assume that the same restriction applies to both reads and
         * writes.
         */
        unsigned int block_size;
        /** Read data from device
         *
         * @v nvs               NVS device
         * @v address           Address from which to read
         * @v data              Data buffer
         * @v len               Length of data buffer
         * @ret rc              Return status code
         *
         * Reads may not cross a block boundary.
         */
        int ( * read ) ( struct nvs_device *nvs, unsigned int address,
                         void *data, size_t len );
        /** Write data to device
         *
         * @v nvs               NVS device
         * @v address           Address to which to write
         * @v data              Data buffer
         * @v len               Length of data buffer
         * @ret rc              Return status code
         *
         * Writes may not cross a block boundary.
         */
        int ( * write ) ( struct nvs_device *nvs, unsigned int address,
                          const void *data, size_t len );
};

extern int nvs_read ( struct nvs_device *nvs, unsigned int address,
                      void *data, size_t len );
extern int nvs_write ( struct nvs_device *nvs, unsigned int address,
                       const void *data, size_t len );

#endif /* _GPXE_NVS_H */