Oops, I've prematurely send previous email.
It seems I managed to get it working after all with franken-opencd.
Just please note that this is _very_ early and unstable work.
I'm posting it here so you will not waste time googling for solutions for problems from my previous mail.
Errata: Don't wire SRST_N - it's not needed and may cause stability issues.
I've pushed openocd with dragonboard cfg file: https://github.com/hallor/openocd branch dragonboard
It is based on Peter Griffin tree, I've added changes made by Jiri Kastner that are pending on openocd gerrit: http://openocd.zylin.com/#/c/3124/6
I didn't took only this change - I replaced whole adi_v5_jtag.c arm_adi_v5.c files. Perhaps I should just forward-port all armv8 code to this branch, but it's left on my TODO list. For now I have to focus on cleaning-up my u-boot tree :)
What is working: - You can attach to board - You can halt cpu, check registers - You can attach with gdb, see backtrace, read memory
What is not working - Most important - resume seems not to work (it generates cpu exception) - Pretty much everything else :)
Regards, Mateusz