82 lines
2.2 KiB
ArmAsm
82 lines
2.2 KiB
ArmAsm
/*
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* Utility functions for FEL mode, when running SPL in AArch64.
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*
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* Copyright (c) 2017 Arm Ltd.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <asm-offsets.h>
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#include <config.h>
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#include <asm/system.h>
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#include <linux/linkage.h>
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/*
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* We don't overwrite save_boot_params() here, to save the FEL state upon
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* entry, since this would run *after* the RMR reset, which clobbers that
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* state.
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* Instead we store the state _very_ early in the boot0 hook, *before*
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* resetting to AArch64.
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*/
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/*
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* The FEL routines in BROM run in AArch32.
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* Reset back into 32-bit mode here and restore the saved FEL state
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* afterwards.
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* Resetting back into AArch32/EL3 using the RMR always enters the BROM,
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* but we can use the CPU hotplug mechanism to branch back to our code
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* immediately.
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*/
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ENTRY(return_to_fel)
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/*
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* the RMR reset will clear all registers, so save the arguments
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* (LR and SP) in the fel_stash structure, which we read anyways later
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*/
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adr x2, fel_stash
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str w0, [x2]
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str w1, [x2, #4]
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adr x1, fel_stash_addr // to find the fel_stash address in AA32
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str w2, [x1]
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ldr x0, =0xfa50392f // CPU hotplug magic
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#ifdef CONFIG_MACH_SUN50I_H616
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ldr x2, =(SUNXI_R_CPUCFG_BASE + 0x1c0)
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str w0, [x2], #0x4
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#elif CONFIG_MACH_SUN50I_H6
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ldr x2, =(SUNXI_RTC_BASE + 0x1b8) // BOOT_CPU_HP_FLAG_REG
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str w0, [x2], #0x4
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#else
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ldr x2, =(SUNXI_CPUCFG_BASE + 0x1a4) // offset for CPU hotplug base
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str w0, [x2, #0x8]
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#endif
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adr x0, back_in_32
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str w0, [x2]
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dsb sy
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isb sy
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mov x0, #2 // RMR reset into AArch32
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dsb sy
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msr RMR_EL3, x0
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isb sy
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1: wfi
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b 1b
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/* AArch32 code to restore the state from fel_stash and return back to FEL. */
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back_in_32:
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.word 0xe59f0028 // ldr r0, [pc, #40] ; load fel_stash address
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.word 0xe5901008 // ldr r1, [r0, #8]
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.word 0xe129f001 // msr CPSR_fc, r1
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.word 0xf57ff06f // isb
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.word 0xe590d000 // ldr sp, [r0]
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.word 0xe590e004 // ldr lr, [r0, #4]
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.word 0xe5901010 // ldr r1, [r0, #16]
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.word 0xee0c1f10 // mcr 15, 0, r1, cr12, cr0, {0} ; VBAR
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.word 0xe590100c // ldr r1, [r0, #12]
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.word 0xee011f10 // mcr 15, 0, r1, cr1, cr0, {0} ; SCTLR
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.word 0xf57ff06f // isb
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.word 0xe12fff1e // bx lr ; return to FEL
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fel_stash_addr:
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.word 0x00000000 // receives fel_stash addr, by AA64 code above
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ENDPROC(return_to_fel)
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