spi_set_chipselect
spi_set_chipselect(spi, 0, 0);
spi_set_chipselect(spi, 0, cs);
spi_set_chipselect(spi, idx, cs[idx]);
spi_set_chipselect(ancillary, 0, chip_select);
spi_set_chipselect(spi, 0, lookup.chip_select);
spi_set_chipselect(spi, idx, SPI_INVALID_CS);
spi_set_chipselect(proxy, 0, chip->chip_select);