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/*
* (C) Copyright 2003, Psyent Corporation <www.psyent.com>
* Scott McNutt <smcnutt@psyent.com>
*
* See file CREDITS for list of people who contributed to this
* project.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of
* the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*/
#include <config.h>
#include <version.h>
#if !defined(CONFIG_IDENT_STRING)
#define CONFIG_IDENT_STRING ""
#endif
#define STATUS_INIT 0x8600 /* IE=1, IPRI=2 */
/*************************************************************************
* RESTART
************************************************************************/
.text
.global _start
_start:
bsr 0f
nop
.long _start
/* GERMS -- The "standard-32" configuration GERMS monitor looks
* for the string "Nios" at flash_base + 0xc (actually it only
* tests for 'N', 'i'). You can leave support for this in place
* as it's only a few words.
*/
. = _start + 0x000c
.string "Nios"
.align 4
0:
/*
* Early setup -- set cwp = HI_LIMIT, IPRI = 2, IE = 1 to
* enable underflow exceptions. Disable cache.
* NOTE: %o7 has return addr -- save in %g7 use later.
*/
mov %g7, %o7
pfx 2 /* WVALID */
rdctl %g0
lsri %g0, 1
pfx %hi(STATUS_INIT)
or %g0, %lo(STATUS_INIT)
wrctl %g0 /* update status */
nop
/*
* STACK
*/
pfx %hi(CFG_INIT_SP)
movi %sp, %lo(CFG_INIT_SP)
pfx %xhi(CFG_INIT_SP)
movhi %sp, %xlo(CFG_INIT_SP)
mov %fp, %sp
pfx %hi(4*16)
subi %sp, %lo(4*16) /* Space for reg window mgmt */
/*
* RELOCATE -- %g7 has return addr from bsr at _start.
*/
pfx %hi(__u_boot_cmd_end)
movi %g5, %lo(__u_boot_cmd_end)
pfx %xhi(__u_boot_cmd_end)
movhi %g5, %xlo(__u_boot_cmd_end) /* %g5 <- end address */
lsli %g7, 1 /* mem = retaddr << 1 */
mov %g6, %g7
subi %g6, 4 /* %g6 <- src addr */
ld %g7, [%g7] /* %g7 <- dst addr */
/* No need to move text sections if we're already located
* at the proper address.
*/
cmp %g7, %g6
ifs cc_z
br reloc
nop /* delay slot */
1: cmp %g7, %g5
skps cc_nz
br 2f
nop /* delay slot */
ld %g0, [%g6]
addi %g6, 4 /* src++ */
st [%g7], %g0
addi %g7, 4 /* dst++ */
br 1b
nop /* delay slot */
2:
/*
* Jump to relocation address
*/
pfx %hi(reloc@h)
movi %g0, %lo(reloc@h)
pfx %xhi(reloc@h)
movhi %g0, %xlo(reloc@h)
jmp %g0
nop /* delay slot */
reloc:
/*
* CLEAR BSS
*/
pfx %hi(__bss_end)
movi %g5, %lo(__bss_end)
pfx %xhi(__bss_end)
movhi %g5, %xlo(__bss_end) /* %g5 <- end address */
pfx %hi(__bss_start)
movi %g7, %lo(__bss_start)
pfx %xhi(__bss_start)
movhi %g7, %xlo(__bss_start) /* %g7 <- end address */
movi %g0, 0
3: cmp %g7, %g5
skps cc_nz
br 4f
nop /* delay slot */
st [%g7], %g0
addi %g7, 4 /* (delay slot) dst++ */
br 3b
nop /* delay slot */
4:
/*
* INIT VECTOR TABLE
*/
pfx %hi(CFG_VECT_BASE)
movi %g0, %lo(CFG_VECT_BASE)
pfx %xhi(CFG_VECT_BASE)
movhi %g0, %xlo(CFG_VECT_BASE) /* dst */
mov %l0, %g0
pfx %hi(_vectors)
movi %g1, %lo(_vectors)
pfx %xhi(_vectors)
movhi %g1, %xlo(_vectors) /* src */
bgen %g2, 6 /* cnt = 64 */
ldp %g3, [%l0, 3] /* bkpt vector */
ldp %g4, [%l0, 4] /* single step vector */
5: ld %g7, [%g1]
addi %g1, 4 /* src++ */
st [%g0], %g7
addi %g0, 4 /* dst++ */
subi %g2, 1 /* cnt-- */
ifrnz %g2
br 5b
nop /* delay slot */
#if defined(CONFIG_ROM_STUBS)
/* Restore the breakpoint and single step exception
* vectors to their original values.
*/
stp [%l0,3], %g3 /* breakpoint */
stp [%l0,4], %g4 /* single step */
#endif
/* For debug startup convenience ... software breakpoints
* set prior to this point may not succeed ;-)
*/
.global __start
__start:
/*
* Call board_init -- never returns
*/
pfx %hi(board_init@h)
movi %g1, %lo(board_init@h)
pfx %xhi(board_init@h)
movhi %g1, %xlo(board_init@h)
call %g1
nop /* Delaly slot */
/* NEVER RETURNS */
/*
* dly_clks -- Nios doesn't have a time/clk reference for simple
* delay loops, so we do our best by counting instruction cycles.
* A control register that counts system clock cycles would be
* a handy feature -- hint for Altera ;-)
*/
.globl dly_clks
/* Each loop is 4 instructions as delay slot is always
* executed. Each instruction is approximately 4 clocks
* (according to some lame info from Altera). So ...
* ... each loop is about 16 clocks.
*/
dly_clks:
lsri %o0, 4 /* cnt/16 */
8: skprnz %o0
br 9f
subi %o0, 1 /* cnt--, Delay slot */
br 8b
nop
9: lret
nop /* Delay slot */
.data
.globl version_string
version_string:
.ascii U_BOOT_VERSION
.ascii " (", __DATE__, " - ", __TIME__, ")"
.ascii CONFIG_IDENT_STRING, "\0"
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