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/*
* Utility functions for FEL mode, when running SPL in AArch64.
*
* Copyright (c) 2017 Arm Ltd.
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <asm/system.h>
#include <linux/linkage.h>
/*
* We don't overwrite save_boot_params() here, to save the FEL state upon
* entry, since this would run *after* the RMR reset, which clobbers that
* state.
* Instead we store the state _very_ early in the boot0 hook, *before*
* resetting to AArch64.
*/
/*
* The FEL routines in BROM run in AArch32.
* Reset back into 32-bit mode here and restore the saved FEL state
* afterwards.
* Resetting back into AArch32/EL3 using the RMR always enters the BROM,
* but we can use the CPU hotplug mechanism to branch back to our code
* immediately.
*/
ENTRY(return_to_fel)
/*
* the RMR reset will clear all registers, so save the arguments
* (LR and SP) in the fel_stash structure, which we read anyways later
*/
adr x2, fel_stash
str w0, [x2]
str w1, [x2, #4]
adr x1, fel_stash_addr // to find the fel_stash address in AA32
str w2, [x1]
ldr x0, =0xfa50392f // CPU hotplug magic
#ifdef CONFIG_MACH_SUN50I_H6
ldr x2, =(SUNXI_RTC_BASE + 0x1b8) // BOOT_CPU_HP_FLAG_REG
str w0, [x2], #0x4
#else
ldr x2, =(SUNXI_CPUCFG_BASE + 0x1a4) // offset for CPU hotplug base
str w0, [x2, #0x8]
#endif
adr x0, back_in_32
str w0, [x2]
dsb sy
isb sy
mov x0, #2 // RMR reset into AArch32
dsb sy
msr RMR_EL3, x0
isb sy
1: wfi
b 1b
/* AArch32 code to restore the state from fel_stash and return back to FEL. */
back_in_32:
.word 0xe59f0028 // ldr r0, [pc, #40] ; load fel_stash address
.word 0xe5901008 // ldr r1, [r0, #8]
.word 0xe129f001 // msr CPSR_fc, r1
.word 0xf57ff06f // isb
.word 0xe590d000 // ldr sp, [r0]
.word 0xe590e004 // ldr lr, [r0, #4]
.word 0xe5901010 // ldr r1, [r0, #16]
.word 0xee0c1f10 // mcr 15, 0, r1, cr12, cr0, {0} ; VBAR
.word 0xe590100c // ldr r1, [r0, #12]
.word 0xee011f10 // mcr 15, 0, r1, cr1, cr0, {0} ; SCTLR
.word 0xf57ff06f // isb
.word 0xe12fff1e // bx lr ; return to FEL
fel_stash_addr:
.word 0x00000000 // receives fel_stash addr, by AA64 code above
ENDPROC(return_to_fel)
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