STM32FX_SPI_DR
.rx = { STM32FX_SPI_DR },
.tx = { STM32FX_SPI_DR },
writew_relaxed(*tx_buf16, spi->base + STM32FX_SPI_DR);
writeb_relaxed(*tx_buf8, spi->base + STM32FX_SPI_DR);
writew_relaxed(*tx_buf16, spi->base + STM32FX_SPI_DR);
writeb_relaxed(*tx_buf8, spi->base + STM32FX_SPI_DR);
*rx_buf16 = readw_relaxed(spi->base + STM32FX_SPI_DR);
*rx_buf8 = readb_relaxed(spi->base + STM32FX_SPI_DR);
*rx_buf16 = readw_relaxed(spi->base + STM32FX_SPI_DR);
*rx_buf8 = readb_relaxed(spi->base + STM32FX_SPI_DR);
readl_relaxed(spi->base + STM32FX_SPI_DR);
readl_relaxed(spi->base + STM32FX_SPI_DR);