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/*
* relocate - i.MX27-specific vector relocation
*
* Copyright (c) 2013 Albert ARIBAUD <albert.u.boot@aribaud.net>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <linux/linkage.h>
/*
* The i.MX27 SoC is very specific with respect to exceptions: it
* does not provide RAM at the high vectors address (0xFFFF0000),
* thus only the low address (0x00000000) is useable; but that is
* in ROM. Therefore, vectors cannot be changed at all.
*
* However, these ROM-based vectors actually just perform indirect
* calls through pointers located in RAM at SoC-specific addresses,
* as follows:
*
* Offset Exception Use by ROM code
* 0x00000000 reset indirect branch to [0x00000014]
* 0x00000004 undefined instruction indirect branch to [0xfffffef0]
* 0x00000008 software interrupt indirect branch to [0xfffffef4]
* 0x0000000c prefetch abort indirect branch to [0xfffffef8]
* 0x00000010 data abort indirect branch to [0xfffffefc]
* 0x00000014 (reserved in ARMv5) vector to ROM reset: 0xc0000000
* 0x00000018 IRQ indirect branch to [0xffffff00]
* 0x0000001c FIQ indirect branch to [0xffffff04]
*
* In order to initialize exceptions on i.MX27, we must copy U-Boot's
* indirect (not exception!) vector table into 0xfffffef0..0xffffff04
* taking care not to copy vectors number 5 (reserved exception).
*/
.section .text.relocate_vectors,"ax",%progbits
ENTRY(relocate_vectors)
ldr r0, [r9, #GD_RELOCADDR] /* r0 = gd->relocaddr */
ldr r1, =32 /* size of vector table */
add r0, r0, r1 /* skip to indirect table */
ldr r1, =0xFFFFFEF0 /* i.MX27 indirect table */
ldmia r0!, {r2-r8} /* load indirect vectors 1..7 */
stmia r1!, {r2-r5, r7,r8} /* write all but vector 5 */
bx lr
ENDPROC(relocate_vectors)
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