u-boot/arch/arm/cpu/armv7/sunxi/fel_utils.S

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ArmAsm
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/*
* Utility functions for FEL mode.
*
* Copyright (c) 2015 Google, Inc
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <asm/system.h>
#include <linux/linkage.h>
ENTRY(save_boot_params)
ldr r0, =fel_stash
str sp, [r0, #0]
str lr, [r0, #4]
mrs lr, cpsr @ Read CPSR
str lr, [r0, #8]
mrc p15, 0, lr, c1, c0, 0 @ Read CP15 SCTLR Register
str lr, [r0, #12]
mrc p15, 0, lr, c12, c0, 0 @ Read VBAR
str lr, [r0, #16]
mrc p15, 0, lr, c1, c0, 0 @ Read CP15 Control Register
str lr, [r0, #20]
b save_boot_params_ret
ENDPROC(save_boot_params)
ENTRY(return_to_fel)
mov sp, r0
mov lr, r1
ldr r0, =fel_stash
ldr r1, [r0, #20]
mcr p15, 0, r1, c1, c0, 0 @ Write CP15 Control Register
ldr r1, [r0, #16]
mcr p15, 0, r1, c12, c0, 0 @ Write VBAR
ldr r1, [r0, #12]
mcr p15, 0, r1, c1, c0, 0 @ Write CP15 SCTLR Register
ldr r1, [r0, #8]
msr cpsr, r1 @ Write CPSR
bx lr
ENDPROC(return_to_fel)