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/*
* (C) Copyright 2004, Psyent Corporation <www.psyent.com>
* Scott McNutt <smcnutt@psyent.com>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <asm-offsets.h>
#include <config.h>
#include <version.h>
/*
* icache and dcache configuration used only for start.S.
* the values are chosen so that it will work for all configuration.
*/
#define ICACHE_LINE_SIZE 32 /* fixed 32 */
#define ICACHE_SIZE_MAX 0x10000 /* 64k max */
#define DCACHE_LINE_SIZE_MIN 4 /* 4, 16, 32 */
#define DCACHE_SIZE_MAX 0x10000 /* 64k max */
/* RESTART */
.text
.global _start, _except_start, _except_end
_start:
wrctl status, r0 /* Disable interrupts */
/*
* ICACHE INIT -- only the icache line at the reset address
* is invalidated at reset. So the init must stay within
* the cache line size (8 words). If GERMS is used, we'll
* just be invalidating the cache a second time. If cache
* is not implemented initi behaves as nop.
*/
ori r4, r0, %lo(ICACHE_LINE_SIZE)
movhi r5, %hi(ICACHE_SIZE_MAX)
ori r5, r5, %lo(ICACHE_SIZE_MAX)
0: initi r5
sub r5, r5, r4
bgt r5, r0, 0b
br _except_end /* Skip the tramp */
/*
* EXCEPTION TRAMPOLINE -- the following gets copied
* to the exception address (below), but is otherwise at the
* default exception vector offset (0x0020).
*/
_except_start:
movhi et, %hi(_exception)
ori et, et, %lo(_exception)
jmp et
_except_end:
/*
* INTERRUPTS -- for now, all interrupts masked and globally
* disabled.
*/
wrctl ienable, r0 /* All disabled */
/*
* DCACHE INIT -- if dcache not implemented, initd behaves as
* nop.
*/
ori r4, r0, %lo(DCACHE_LINE_SIZE_MIN)
movhi r5, %hi(DCACHE_SIZE_MAX)
ori r5, r5, %lo(DCACHE_SIZE_MAX)
mov r6, r0
1: initd 0(r6)
add r6, r6, r4
bltu r6, r5, 1b
/*
* RELOCATE CODE, DATA & COMMAND TABLE -- the following code
* assumes code, data and the command table are all
* contiguous. This lets us relocate everything as a single
* block. Make sure the linker script matches this ;-)
*/
nextpc r4
_cur: movhi r5, %hi(_cur - _start)
ori r5, r5, %lo(_cur - _start)
sub r4, r4, r5 /* r4 <- cur _start */
mov r8, r4
movhi r5, %hi(_start)
ori r5, r5, %lo(_start) /* r5 <- linked _start */
mov sp, r5 /* initial stack below u-boot code */
beq r4, r5, 3f
movhi r6, %hi(CONFIG_SYS_MONITOR_LEN)
ori r6, r6, %lo(CONFIG_SYS_MONITOR_LEN)
add r6, r6, r5
2: ldwio r7, 0(r4)
addi r4, r4, 4
stwio r7, 0(r5)
addi r5, r5, 4
bne r5, r6, 2b
3:
/* JUMP TO RELOC ADDR */
movhi r4, %hi(_reloc)
ori r4, r4, %lo(_reloc)
jmp r4
_reloc:
/* STACK INIT -- zero top two words for call back chain. */
addi sp, sp, -8
stw r0, 0(sp)
stw r0, 4(sp)
mov fp, sp
/* Allocate and zero GD, update SP */
mov r4, sp
movhi r2, %hi(board_init_f_mem@h)
ori r2, r2, %lo(board_init_f_mem@h)
callr r2
/* Update stack- and frame-pointers */
mov sp, r2
mov fp, sp
/* Call board_init_f -- never returns */
mov r4, r0
movhi r2, %hi(board_init_f@h)
ori r2, r2, %lo(board_init_f@h)
callr r2
/*
* NEVER RETURNS -- but branch to the _start just
* in case ;-)
*/
br _start
/*
* relocate_code -- Nios2 handles the relocation above. But
* the generic board code monkeys with the heap, stack, etc.
* (it makes some assumptions that may not be appropriate
* for Nios). Nevertheless, we capitulate here.
*
* We'll call the board_init_r from here since this isn't
* supposed to return.
*
* void relocate_code (ulong sp, gd_t *global_data,
* ulong reloc_addr)
* __attribute__ ((noreturn));
*/
.text
.global relocate_code
relocate_code:
mov sp, r4 /* Set the new sp */
mov r4, r5
/*
* ZERO BSS/SBSS -- bss and sbss are assumed to be adjacent
* and between __bss_start and __bss_end.
*/
movhi r5, %hi(__bss_start)
ori r5, r5, %lo(__bss_start)
movhi r6, %hi(__bss_end)
ori r6, r6, %lo(__bss_end)
beq r5, r6, 5f
4: stw r0, 0(r5)
addi r5, r5, 4
bne r5, r6, 4b
5:
movhi r8, %hi(board_init_r@h)
ori r8, r8, %lo(board_init_r@h)
callr r8
ret
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