Boilerplate code taken from Linaro OP-TEE pseudo TA example: $(OPTEE_LOCATION)/optee_os/core/arch/arm/pta/stats.c

Pseduo-TA implementation to interact with Raspberry Pi 3 GPIO pin 18. Exposes the following TA commands: GPIO_ON Send high signal to GPIO 18 GPIO_OFF Send low signal to GPIO 18 TEST_PSEUDO_TA Test Pseduo TA