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sunxi: A64: do an RMR switch if started in AArch32 mode

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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>
This commit is contained in:
Andre Przywara
2017-01-02 11:48:36 +00:00
committed by Jagan Teki
parent b5402d13d4
commit 83843c9b3a
3 changed files with 85 additions and 0 deletions
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30
arch/arm/include/asm/arch-sunxi/boot0.h
View File

@@ -4,6 +4,36 @@
* 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.
* Refer to arch/arm/mach-sunxi/rmr_switch.S for the original source.
*/
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
#ifdef CONFIG_SPL_BUILD
.word CONFIG_SPL_TEXT_BASE
#else
.word CONFIG_SYS_TEXT_BASE
#endif
#else
/* normal execution */
b reset
#endif