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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_H616
- ldr x2, =(SUNXI_R_CPUCFG_BASE + 0x1c0)
- str w0, [x2], #0x4
- #elif 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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