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 */ 69
