Rewrite dualboot in C code instead of assembly. Also properly
handle subtarget and simply Makefile. This should make the
dualboot stub more readable and easier to extend. The new code
also gracefully handles power up from RTC alarm on imx233.
Change-Id: I7c225254b1463a97e76b6cb4de476aa2d2c9d2f9
The previous dualboot scheme had a major flow: it needed to hold
menu to boot OF but the X-Fi2 boot in recovery mode with menu!
It was possible but very trick to enter the OF with USB plugged.
This code provides a new scheme:
- no USB plugged: boot to OF when menu is pressed
- USB plugged: boot to OF when power is pressed
Change-Id: Ia6e76d3ada1f67137b727daa050cf6c77afbbfb9
Only boot to rockbox if the power button is hold sufficiently long.
For consistency, use the same mechanism as the OF:
- read PSWITCH 550000 times
- boot if PSWITCH=1 at least 400000 out of 550000 times
Only apply the delay if Volume Down is not hold,
so that the OF and RB delay don't cumulate.
Change-Id: I1e8a4cd108c56bf784fcf1c320f7a001ef161701
