RSPI_SSLP
sslp = rspi_read8(rspi, RSPI_SSLP);
rspi_write8(rspi, sslp, RSPI_SSLP);
writeb(BIT(spi_get_chipselect(spi, 0)), rspi->base + RSPI_SSLP);
writeb(0, rspi->base + RSPI_SSLP);