To return a 64-bit Allwinner chip back to the 32-bit BootROM code, we
have some embedded AArch32 code that restores the CPU state, before
branching back to the BootROM. At the moment the pointer to the buffer
with that state is located *after* the code, which makes the PC relative
code fragile: adding or removing instructions will change the distance
to that pointer variable.
The "new" Allwinner A523 SoC requires more state to be restored (GICv3
system registers), but we must do that *only* on that SoC. Conditional
compilation sounds like the easiest solution, but would mean that the
distance to that pointer would change.
Solve this rather easily by moving the pointer to the *front* of the
code: we load that pointer in the first instruction, so the distance
would always stay the same. Later in the code we won't need PC relative
addressing anymore, so this code can grow or shrink easily, for instance
due to conditional compilation.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
At the moment we have each SoC's memory map defined in its own cpu.h,
which is included in include/configs/sunxi_common.h. This will be a
problem with the introduction of Allwinner RISC-V support.
Remove the inclusion of that header file from the common config header,
instead move the required serial base addresses (for the SPL) into a
separate header file. Then include the original cpu.h file only where
we really need it, which is only under arch/arm now.
This disentangles the architecture specific header files from the
generic code.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Both the values and the MMIO addresses that we need during the 64-bit FEL
restore are smaller than 2^32, so we don't need to do any 64-bit loads.
Change the loads to only load 32 bits worth of data, that saves us some
bytes for storing the values.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Samuel Holland <samuel@sholland.org>
Tested-by: Samuel Holland <samuel@sholland.org>
H616 uses different address for reset. Add it.
Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
So far we did not support the BootROM based FEL USB debug mode on the
64-bit builds for Allwinner SoCs: The BootROM is using AArch32, but the
SPL runs in AArch64.
Returning back to AArch32 was not working as expected, since the RMR
reset into 32-bit mode always starts execution in the BootROM, but not
in the FEL routine.
After some debug and research and with help via IRC, the CPU hotplug
mechanism emerged as a solution: If a certain R_CPUCFG register contains
some magic, the BootROM will immediately branch to an address stored in
some other register. This works well for our purposes.
Enable the FEL feature by providing early AArch32 code to first save the
FEL state, *before* initially entering AArch64.
If we eventually determine that we should return to FEL, we reset back
into AArch32, and use the CPU hotplug mechanism to run some small
AArch32 code snippet that restores the initially saved FEL state.
That allows the normal AArch64 SPL build to be loaded via the sunxi-fel
tool, with it returning into FEL mode, so that other payloads can be
transferred via FEL as well.
Tested on A64, H5 and H6.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Tested-by: Icenowy Zheng <icenowy@aosc.io>
Acked-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Priit Laes <plaes@plaes.org> (on Olimex A64-Olinuxino)
