u-boot-brain/arch/arm/mach-uniphier/arm64/lowlevel_init.S

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * Copyright (C) 2017 Socionext Inc.
 */

#include <linux/linkage.h>

ENTRY(lowlevel_init)
	/* LD20 needs the following code to boot.  I do not know why. */
	mrs	x0, sctlr_el1
	msr	sctlr_el1, x0
	ret
ENDPROC(lowlevel_init)
SPDX: Convert all of our single license tags to Linux Kernel style When U-Boot started using SPDX tags we were among the early adopters and there weren't a lot of other examples to borrow from. So we picked the area of the file that usually had a full license text and replaced it with an appropriate SPDX-License-Identifier: entry. Since then, the Linux Kernel has adopted SPDX tags and they place it as the very first line in a file (except where shebangs are used, then it's second line) and with slightly different comment styles than us. In part due to community overlap, in part due to better tag visibility and in part for other minor reasons, switch over to that style. This commit changes all instances where we have a single declared license in the tag as both the before and after are identical in tag contents. There's also a few places where I found we did not have a tag and have introduced one. Signed-off-by: Tom Rini <trini@konsulko.com> 2018-05-07 06:58:06 +09:00			`/* SPDX-License-Identifier: GPL-2.0+ */`
ARM: uniphier: add weird workaround code for LD20 When booting from ARM Trusted Firmware, U-Boot runs in EL1-NS. The boot flow is as follows: BL1 -> BL2 -> BL31 -> BL33 (i.e. U-Boot) This boot sequence works fine for LD11 SoC (Cortex-A53), but LD20 SoC (Cortex-A72) hangs in U-Boot. The solution I found is to read sctlr_el1 and write back the value as-is. This should be no effect, but surprisingly fixes the problem for LD20 to boot. I do not know why. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> 2017-05-12 22:49:02 +09:00			`/*`
			`* Copyright (C) 2017 Socionext Inc.`
			`*/`

			`#include <linux/linkage.h>`

			`ENTRY(lowlevel_init)`
			`/* LD20 needs the following code to boot. I do not know why. */`
			`mrs x0, sctlr_el1`
			`msr sctlr_el1, x0`
			`ret`
			`ENDPROC(lowlevel_init)`