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.przywara@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? 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.
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