src/include/gpxe/spi_bit.h

   1 #ifndef _GPXE_SPI_BIT_H
   2 #define _GPXE_SPI_BIT_H
   3
   4 /** @file
   5  *
   6  * SPI bit-bashing interface
   7  *
   8  */
   9
  10 #include <gpxe/spi.h>
  11 #include <gpxe/bitbash.h>
  12
  13 /** A bit-bashing SPI bus */
  14 struct spi_bit_basher {
  15         /** SPI bus */
  16         struct spi_bus bus;
  17         /** Bit-bashing interface */
  18         struct bit_basher basher;
  19         /** Endianness of data
  20          *
  21          * SPI commands and addresses are always big-endian (i.e. MSB
  22          * transmitted first on the wire), but some cards
  23          * (e.g. natsemi) choose to regard the data stored in the
  24          * EEPROM as little-endian (i.e. LSB transmitted first on the
  25          * wire).
  26          */
  27         int endianness;
  28 };
  29
  30 /** Bit indices used for SPI bit-bashing interface */
  31 enum {
  32         /** Serial clock */
  33         SPI_BIT_SCLK = 0,
  34         /** Master Out Slave In */
  35         SPI_BIT_MOSI,
  36         /** Master In Slave Out */
  37         SPI_BIT_MISO,
  38         /** Slave 0 select */
  39         SPI_BIT_SS0,
  40 };
  41
  42 /**
  43  * Determine bit index for a particular slave
  44  *
  45  * @v slave             Slave number
  46  * @ret index           Bit index (i.e. SPI_BIT_SSN, where N=slave)
  47  */
  48 #define SPI_BIT_SS( slave ) ( SPI_BIT_SS0 + (slave) )
  49
  50 /** Delay between SCLK transitions */
  51 #define SPI_BIT_UDELAY 1
  52
  53 /** SPI bit basher treats data as big-endian */
  54 #define SPI_BIT_BIG_ENDIAN 0
  55
  56 /** SPI bit basher treats data as little-endian */
  57 #define SPI_BIT_LITTLE_ENDIAN 1
  58
  59 extern void init_spi_bit_basher ( struct spi_bit_basher *spibit );
  60
  61 #endif /* _GPXE_SPI_BIT_H */