Синхронный последовательный интерфейс: список регистров

  TB_WR

TX FIFO Write Buffer Write Enable

  TB_CNT

TX FIFO Write Buffer Counter
These bits indicate the number of words in TX FIFO Write Buffer

  Unused

  TF_CNT

TX FIFO Counter
These bits indicate the number of words in TX FIFO
0: 0 byte in TX FIFO
1: 1 byte in TX FIFO
***
64: 64 bytes in TX FIFO
other: Reserved

  RB_WR

RX FIFO Read Buffer Write Enable

  RB_CNT

RX FIFO Read Buffer Counter
These bits indicate the number of words in RX FIFO Read Buffer

  Unused

  RF_CNT

RX FIFO Counter
These bits indicate the number of words in RX FIFO
0: 0 byte in RX FIFO
1: 1 byte in RX FIFO
***
64: 64 bytes in RX FIFO
other: Reserved

Команда U-Boot для чтения регистра

Bit fields structure

typedef union  spi_fsr
{
  struct
  {
   unsigned rf_cnt : 8;
   unsigned unused0 : 4;
   unsigned rb_cnt : 3;
   unsigned rb_wr : 1;
   unsigned tf_cnt : 8;
   unsigned unused1 : 4;
   unsigned tb_cnt : 3;
   unsigned tb_wr : 1;
  } b;
   unsigned long w;
} SPI_FSR