Absolute minimum bare metal app
I'm having a lot of trouble getting u-boot SPL to build/do anything on an Arria V board, so I want to make the absolute bare minimum software app with just enough code to get an HPS GPIO wiggling (GPIO64 in the HPS parameters page), so I can see it on the oscope, and prove it's running something. Can someone review these steps and let me know if anything is missing:
1) startup code at 0xffff0000, setup stack pointer, branch to main
2) call "spl_board_init()" from spl.c, which utilizes the "generated" settings from Quartus, which should configure clocks, initialize IO pins with the scan manager/pin mux, unthaw IO banks
3) disable both L4 watchdogs
4) clear reset bit for GPIO2 in the reset manager
5) in the GPIO2 register space, set bit 6 of the DDR register high to configure GPIO64 as output
6) in the GPIO2 register space, set/clear bit 6 of the DR register to toggle GPIO64 pin high/low.