b53_spi_read_reg
ret = b53_spi_read_reg(spi, reg, &rxbuf, 1);
ret = b53_spi_read_reg(spi, B53_SPI_STATUS, &rxbuf, 1);
return b53_spi_read_reg(spi, B53_SPI_DATA, data, len);
ret = b53_spi_read_reg(spi, B53_SPI_STATUS, &rxbuf, 1);