Hi,
On 21/11/16 16:34, Alexander Graf wrote:
>
>
> On 20/11/2016 15:57, Andre Przywara 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.
>>
>> 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(+)
>>
>> diff --git a/arch/arm/include/asm/arch-sunxi/boot0.h
>> b/arch/arm/include/asm/arch-sunxi/boot0.h
>> index 6a13db5..c31a2af 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)
>> /* 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 0xe3a01617 // mov r1, #0x1700000
>> + .word 0xe38110a0 // orr r1, r1, #0xa0
>
> Is this address guaranteed to stay the same for newer chips?
AW and stay the same? ;-)
> Maybe it'd
> be better to use a pc-relative load and put it in as .word like you do
> below for the text base address.
Yes, good plan.
Cheers,
Andre
>
>
> Alex
>
>> + .word 0xe59f0020 // ldr r0, [pc, #32]
>> + .word 0xe5810000 // str r0, [r1]
>> + .word 0xf57ff04f // dsb sy
>> + .word 0xf57ff06f // isb sy
>> + .word 0xee1c0f50 // mrc 15, 0, r0, cr12, cr0, {2}
>> + .word 0xe3800003 // orr r0, r0, #3
>> + .word 0xee0c0f50 // mcr 15, 0, r0, cr12, cr0, {2}
>> + .word 0xf57ff06f // isb sy
>> + .word 0xe320f003 // wfi
>> + .word 0xeafffffd // b @wfi
>> +#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
>> +
>> config DRAM_TYPE
>> int "sunxi dram type"
>> depends on MACH_SUN8I_A83T
>>
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