fsi_spi_read_reg
int rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, status);
rc = fsi_spi_read_reg(ctx, SPI_FSI_DATA_RX, &in);
rc = fsi_spi_read_reg(ctx, SPI_FSI_STATUS, &status);
rc = fsi_spi_read_reg(ctx, SPI_FSI_CLOCK_CFG, &clock_cfg);