how to implement full duplex on the spi interface

hello everyone. i want to implement the exchange via the spi interface. installed the mraa library and made stm32 as a slave. using the example from libmraa , i was able to forward a byte to the stm and light the LED . is it possible to implement full duplex so that when the stm responds to radxa, radxa can receive information into some buffer of its own? and can radxa be a slave?