Board Configuration Files

I want to run PX4 on Raspberry Pi 3 using custom sensors.

Found the board startup and configuration files located in Firmware/boards/px4/raspberrypi/ but could not figure out how and where the Raspberry Pi GPIOs have been configured. Which file configures the pin assignment?

Also looked into Firmware/boards/emlid/navio2/ but could not find the detail.

I specifically need information for the following Raspberry Pi pins

18 GPIO 24 (assigned to RCIO PC10 for Navio2)
29 GPIO 5 (assigned to RCIO PC11 for Navio2)

32 GPIO 12 (assigned to RCIO Clock for Navio2)
33 GPIO 13 (assigned to RCIO Data for Navio2)

35 GPIO 19 (assigned to RCIO MISO for Navio2)
36 GPIO 16 (assigned to RCIO Chip Select for Navio2)
38 GPIO 20 (assigned to RCIO MOSI for Navio2)
40 GPIO 21 (assigned to RCIO SCLK for Navio2)

Please don’t double and triple post, follow up here: Raspberry Pi Board Configuration Files