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/*
* Startup Code for MIPS32 CPU-core
*
* Copyright (c) 2003 Wolfgang Denk <wd@denx.de>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#ifndef CONFIG_SYS_MIPS_CACHE_MODE
#define CONFIG_SYS_MIPS_CACHE_MODE CONF_CM_CACHABLE_NONCOHERENT
#endif
/*
* For the moment disable interrupts, mark the kernel mode and
* set ST0_KX so that the CPU does not spit fire when using
* 64-bit addresses.
*/
.macro setup_c0_status set clr
.set push
mfc0 t0, CP0_STATUS
or t0, ST0_CU0 | \set | 0x1f | \clr
xor t0, 0x1f | \clr
mtc0 t0, CP0_STATUS
.set noreorder
sll zero, 3 # ehb
.set pop
.endm
.set noreorder
.globl _start
.text
_start:
/* U-boot entry point */
b reset
nop
.org 0x10
#if defined(CONFIG_SYS_XWAY_EBU_BOOTCFG)
/*
* Almost all Lantiq XWAY SoC devices have an external bus unit (EBU) to
* access external NOR flashes. If the board boots from NOR flash the
* internal BootROM does a blind read at address 0xB0000010 to read the
* initial configuration for that EBU in order to access the flash
* device with correct parameters. This config option is board-specific.
*/
.word CONFIG_SYS_XWAY_EBU_BOOTCFG
.word 0x0
#elif defined(CONFIG_QEMU_MALTA)
/*
* Linux expects the Board ID here.
*/
.word 0x00000420 # 0x420 (Malta Board with CoreLV)
.word 0x00000000
#endif
.org 0x200
/* TLB refill, 32 bit task */
1: b 1b
nop
.org 0x280
/* XTLB refill, 64 bit task */
1: b 1b
nop
.org 0x300
/* Cache error exception */
1: b 1b
nop
.org 0x380
/* General exception */
1: b 1b
nop
.org 0x400
/* Catch interrupt exceptions */
1: b 1b
nop
.org 0x480
/* EJTAG debug exception */
1: b 1b
nop
.align 4
reset:
/* Clear watch registers */
mtc0 zero, CP0_WATCHLO
mtc0 zero, CP0_WATCHHI
/* WP(Watch Pending), SW0/1 should be cleared */
mtc0 zero, CP0_CAUSE
setup_c0_status 0 0
/* Init Timer */
mtc0 zero, CP0_COUNT
mtc0 zero, CP0_COMPARE
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
/* CONFIG0 register */
li t0, CONF_CM_UNCACHED
mtc0 t0, CP0_CONFIG
#endif
/* Initialize $gp */
bal 1f
nop
.word _gp
1:
lw gp, 0(ra)
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
/* Initialize any external memory */
la t9, lowlevel_init
jalr t9
nop
/* Initialize caches... */
la t9, mips_cache_reset
jalr t9
nop
/* ... and enable them */
li t0, CONFIG_SYS_MIPS_CACHE_MODE
mtc0 t0, CP0_CONFIG
#endif
/* Set up temporary stack */
li sp, CONFIG_SYS_SDRAM_BASE + CONFIG_SYS_INIT_SP_OFFSET
la t9, board_init_f
jr t9
nop
/*
* void relocate_code (addr_sp, gd, addr_moni)
*
* This "function" does not return, instead it continues in RAM
* after relocating the monitor code.
*
* a0 = addr_sp
* a1 = gd
* a2 = destination address
*/
.globl relocate_code
.ent relocate_code
relocate_code:
move sp, a0 # set new stack pointer
move s0, a1 # save gd in s0
move s2, a2 # save destination address in s2
li t0, CONFIG_SYS_MONITOR_BASE
sub s1, s2, t0 # s1 <-- relocation offset
la t3, in_ram
lw t2, -12(t3) # t2 <-- __image_copy_end
move t1, a2
add gp, s1 # adjust gp
/*
* t0 = source address
* t1 = target address
* t2 = source end address
*/
1:
lw t3, 0(t0)
sw t3, 0(t1)
addu t0, 4
blt t0, t2, 1b
addu t1, 4
/* If caches were enabled, we would have to flush them here. */
sub a1, t1, s2 # a1 <-- size
la t9, flush_cache
jalr t9
move a0, s2 # a0 <-- destination address
/* Jump to where we've relocated ourselves */
addi t0, s2, in_ram - _start
jr t0
nop
.word __rel_dyn_end
.word __rel_dyn_start
.word __image_copy_end
.word _GLOBAL_OFFSET_TABLE_
.word num_got_entries
in_ram:
/*
* Now we want to update GOT.
*
* GOT[0] is reserved. GOT[1] is also reserved for the dynamic object
* generated by GNU ld. Skip these reserved entries from relocation.
*/
lw t3, -4(t0) # t3 <-- num_got_entries
lw t8, -8(t0) # t8 <-- _GLOBAL_OFFSET_TABLE_
add t8, s1 # t8 now holds relocated _G_O_T_
addi t8, t8, 8 # skipping first two entries
li t2, 2
1:
lw t1, 0(t8)
beqz t1, 2f
add t1, s1
sw t1, 0(t8)
2:
addi t2, 1
blt t2, t3, 1b
addi t8, 4
/* Update dynamic relocations */
lw t1, -16(t0) # t1 <-- __rel_dyn_start
lw t2, -20(t0) # t2 <-- __rel_dyn_end
b 2f # skip first reserved entry
addi t1, 8
1:
lw t8, -4(t1) # t8 <-- relocation info
li t3, 3
bne t8, t3, 2f # skip non R_MIPS_REL32 entries
nop
lw t3, -8(t1) # t3 <-- location to fix up in FLASH
lw t8, 0(t3) # t8 <-- original pointer
add t8, s1 # t8 <-- adjusted pointer
add t3, s1 # t3 <-- location to fix up in RAM
sw t8, 0(t3)
2:
blt t1, t2, 1b
addi t1, 8 # each rel.dyn entry is 8 bytes
/*
* Clear BSS
*
* GOT is now relocated. Thus __bss_start and __bss_end can be
* accessed directly via $gp.
*/
la t1, __bss_start # t1 <-- __bss_start
la t2, __bss_end # t2 <-- __bss_end
1:
sw zero, 0(t1)
blt t1, t2, 1b
addi t1, 4
move a0, s0 # a0 <-- gd
la t9, board_init_r
jr t9
move a1, s2
.end relocate_code
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