I use the SPI port on J21(TX2 Dev kit) but I need 3 Chip select lines on the bus.I have got the SPI working with the default CS on J21. How do I configure the dtb file to also use gpio_exp_p16 and 17 on the J21 header as chip selects?
Please refer nvidia,spi-tegra114.txt under Documentation/devicetree/bindings/spi
spi-client device controller properties:
- nvidia,chipselect-gpio: Chipselect GPIO number as per gpio binding.
Please check spi-bus.txt for spi bus .
for example the controller has 2 CS lines, and the cs-gpios property looks like this:
cs-gpios = <&gpio1 0 0> <0> <&gpio1 1 0> <&gpio1 2 0>;