diff options
| author | Andre Przywara <andre.przywara@arm.com> | 2017-01-02 11:48:36 (GMT) |
|---|---|---|
| committer | Jagan Teki <jagan@openedev.com> | 2017-01-04 15:37:42 (GMT) |
| commit | 83843c9b3ac511e97b844db70553a2a8966dd44a (patch) | |
| tree | 378df5a99de591aa8a09664a17f4c6b5e6e9e5fb /board | |
| parent | b5402d13d4a3fe49af884ba7d5d32700af911536 (diff) | |
| download | u-boot-83843c9b3ac511e97b844db70553a2a8966dd44a.tar.xz | |
sunxi: A64: do an RMR switch if started in AArch32 mode
The Allwinner A64 SoC starts execution in AArch32 mode, and both
the boot ROM and Allwinner's boot0 keep running in this mode.
So U-Boot gets entered in 32-bit, although we want it to run in AArch64.
By using a "magic" instruction, which happens to be an almost-NOP in
AArch64 and a branch in AArch32, we differentiate between being
entered in 64-bit or 32-bit mode.
If in 64-bit mode, we proceed with the branch to reset, but in 32-bit
mode we trigger an RMR write to bring the core into AArch64/EL3 and
re-enter U-Boot at CONFIG_SYS_TEXT_BASE.
This allows a 64-bit U-Boot to be both entered in 32 and 64-bit mode,
so we can use the same start code for the SPL and the U-Boot proper.
We use the existing custom header (boot0.h) functionality, but restrict
the existing boot0 header reservation to the non-SPL build now. A SPL
wouldn't need such header anyway. This allows to have both options
defined and lets us use one for the SPL and the other for U-Boot proper.
Also add arch/arm/mach-sunxi/rmr_switch.S, which contains the original
ARM assembly code and instructions how to re-generate the encoded
version.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Diffstat (limited to 'board')
| -rw-r--r-- | board/sunxi/Kconfig | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig index 0cd57a2..f020573 100644 --- a/board/sunxi/Kconfig +++ b/board/sunxi/Kconfig @@ -142,6 +142,20 @@ config RESERVE_ALLWINNER_BOOT0_HEADER blob relies on this information to load and execute U-Boot. Only needed on 64-bit Allwinner boards so far when using boot0. +config ARM_BOOT_HOOK_RMR + bool + depends on ARM64 + default y + select ENABLE_ARM_SOC_BOOT0_HOOK + ---help--- + Insert some ARM32 code at the very beginning of the U-Boot binary + which uses an RMR register write to bring the core into AArch64 mode. + The very first instruction acts as a switch, since it's carefully + chosen to be a NOP in one mode and a branch in the other, so the + code would only be executed if not already in AArch64. + This allows both the SPL and the U-Boot proper to be entered in + either mode and switch to AArch64 if needed. + config DRAM_TYPE int "sunxi dram type" depends on MACH_SUN8I_A83T |