Hi Andre,
On 4 December 2016 at 18:52, Andre Przywara <andre.przyw...@arm.com> wrote:
> 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.
>
> Signed-off-by: Andre Przywara <andre.przyw...@arm.com>
> ---
> arch/arm/include/asm/arch-sunxi/boot0.h | 27 +++++++++++++++++++++++++++
> board/sunxi/Kconfig | 5 +++++
> 2 files changed, 32 insertions(+)
Reviewed-by: Simon Glass <s...@chromium.org>
>
> diff --git a/arch/arm/include/asm/arch-sunxi/boot0.h
> b/arch/arm/include/asm/arch-sunxi/boot0.h
> index 6a13db5..7799a03 100644
> --- a/arch/arm/include/asm/arch-sunxi/boot0.h
> +++ b/arch/arm/include/asm/arch-sunxi/boot0.h
> @@ -4,6 +4,33 @@
> * SPDX-License-Identifier: GPL-2.0+
> */
>
> +#if defined(CONFIG_RESERVE_ALLWINNER_BOOT0_HEADER) &&
> !defined(CONFIG_SPL_BUILD)
> /* reserve space for BOOT0 header information */
> b reset
> .space 1532
> +#elif defined(CONFIG_ARM_BOOT_HOOK_RMR)
> +/* switch into AArch64 if needed */
> + tst x0, x0 // this is "b #0x84" in ARM
> + b reset
> + .space 0x7c
> + .word 0xe59f1024 // ldr r1, [pc, #36] ; 0x170000a0
> + .word 0xe59f0024 // ldr r0, [pc, #36] ; CONFIG_*_TEXT_BASE
> + .word 0xe5810000 // str r0, [r1]
> + .word 0xf57ff04f // dsb sy
> + .word 0xf57ff06f // isb sy
> + .word 0xee1c0f50 // mrc 15, 0, r0, cr12, cr0, {2} ; RMR
> + .word 0xe3800003 // orr r0, r0, #3
> + .word 0xee0c0f50 // mcr 15, 0, r0, cr12, cr0, {2} ; RMR
> + .word 0xf57ff06f // isb sy
> + .word 0xe320f003 // wfi
> + .word 0xeafffffd // b @wfi
> + .word 0x017000a0 // writeable RVBAR mapping address
How come you cannot use the assembler here?
> +#ifdef CONFIG_SPL_BUILD
> + .word CONFIG_SPL_TEXT_BASE
> +#else
> + .word CONFIG_SYS_TEXT_BASE
> +#endif
> +#else
> +/* normal execution */
> + b reset
> +#endif
> diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig
> index 0cd57a2..ba72e76 100644
> --- a/board/sunxi/Kconfig
> +++ b/board/sunxi/Kconfig
> @@ -142,6 +142,11 @@ 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
> + default y if ARM64
> + select ENABLE_ARM_SOC_BOOT0_HOOK
help?
> +
> config DRAM_TYPE
> int "sunxi dram type"
> depends on MACH_SUN8I_A83T
> --
> 2.8.2
>
Regards,
Simon
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