blob: 7cbd1a78f089e0b35415a42e7c803242306c0e2c [file] [log] [blame]
wdenk4a551702003-10-08 23:26:14 +00001/*
2 * (C) Copyright 2003, Psyent Corporation <www.psyent.com>
3 * Scott McNutt <smcnutt@psyent.com>
4 *
5 * See file CREDITS for list of people who contributed to this
6 * project.
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of
11 * the License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
21 * MA 02111-1307 USA
22 */
23
24
25#include <config.h>
26#include <version.h>
27
28#if !defined(CONFIG_IDENT_STRING)
29#define CONFIG_IDENT_STRING ""
30#endif
31
32#define STATUS_INIT 0x8600 /* IE=1, IPRI=2 */
33
34/*************************************************************************
35 * RESTART
36 ************************************************************************/
37
38 .text
39 .global _start
40
41_start:
42 bsr 0f
43 nop
44 .long _start
45
46 /* GERMS -- The "standard-32" configuration GERMS monitor looks
47 * for the string "Nios" at flash_base + 0xc (actually it only
48 * tests for 'N', 'i'). You can leave support for this in place
49 * as it's only a few words.
50 */
51 . = _start + 0x000c
52 .string "Nios"
53
54 .align 4
550:
56 /*
57 * Early setup -- set cwp = HI_LIMIT, IPRI = 2, IE = 1 to
58 * enable underflow exceptions. Disable cache.
59 * NOTE: %o7 has return addr -- save in %g7 use later.
60 */
61 mov %g7, %o7
62
63 pfx 2 /* WVALID */
64 rdctl %g0
65 lsri %g0, 1
66 pfx %hi(STATUS_INIT)
67 or %g0, %lo(STATUS_INIT)
68 wrctl %g0 /* update status */
69 nop
70
71 /*
72 * STACK
73 */
74 pfx %hi(CFG_INIT_SP)
75 movi %sp, %lo(CFG_INIT_SP)
76 pfx %xhi(CFG_INIT_SP)
77 movhi %sp, %xlo(CFG_INIT_SP)
78 mov %fp, %sp
79
80 pfx %hi(4*16)
81 subi %sp, %lo(4*16) /* Space for reg window mgmt */
82
83 /*
84 * RELOCATE -- %g7 has return addr from bsr at _start.
85 */
86 pfx %hi(__u_boot_cmd_end)
87 movi %g5, %lo(__u_boot_cmd_end)
88 pfx %xhi(__u_boot_cmd_end)
89 movhi %g5, %xlo(__u_boot_cmd_end) /* %g5 <- end address */
90
91 lsli %g7, 1 /* mem = retaddr << 1 */
92 mov %g6, %g7
93 subi %g6, 4 /* %g6 <- src addr */
94 ld %g7, [%g7] /* %g7 <- dst addr */
95
961: cmp %g7, %g5
97 skps cc_nz
98 br 2f
99 nop /* delay slot */
100
101 ld %g0, [%g6]
102 addi %g6, 4 /* src++ */
103 st [%g7], %g0
104 addi %g7, 4 /* dst++ */
105 br 1b
106 nop /* delay slot */
1072:
108
109 /*
110 * Jump to relocation address
111 */
112 pfx %hi(reloc@h)
113 movi %g0, %lo(reloc@h)
114 pfx %xhi(reloc@h)
115 movhi %g0, %xlo(reloc@h)
116 jmp %g0
117reloc:
118
119 /*
120 * CLEAR BSS
121 */
122 pfx %hi(__bss_end)
123 movi %g5, %lo(__bss_end)
124 pfx %xhi(__bss_end)
125 movhi %g5, %xlo(__bss_end) /* %g5 <- end address */
126 pfx %hi(__bss_start)
127 movi %g7, %lo(__bss_start)
128 pfx %xhi(__bss_start)
129 movhi %g7, %xlo(__bss_start) /* %g7 <- end address */
130
131 movi %g0, 0
1323: cmp %g7, %g5
133 skps cc_nz
134 br 4f
135 nop /* delay slot */
136
137 st [%g7], %g0
138 addi %g7, 4 /* (delay slot) dst++ */
139 br 3b
140 nop /* delay slot */
1414:
142
143 /*
144 * Call board_init -- never returns
145 */
146 pfx %hi(board_init@h)
147 movi %g1, %lo(board_init@h)
148 pfx %xhi(board_init@h)
149 movhi %g1, %xlo(board_init@h)
150 call %g1
151 nop /* Delaly slot */
152 /* NEVER RETURNS */
153
154/*
155 * dly_clks -- Nios doesn't have a time/clk reference for simple
156 * delay loops, so we do our best by counting instruction cycles.
157 * A control register that counts system clock cycles would be
158 * a handy feature -- hint for Altera ;-)
159 */
160 .globl dly_clks
161 /* Each loop is 4 instructions as delay slot is always
162 * executed. Each instruction is approximately 4 clocks
163 * (according to some lame info from Altera). So ...
164 * ... each loop is about 16 clocks.
165 */
166
167dly_clks:
168 lsri %o0, 4 /* cnt/16 */
169
1708: skprnz %o0
171 br 9f
172 subi %o0, 1 /* cnt--, Delay slot */
173 br 8b
174 nop
175
1769: lret
177 nop /* Delay slot */
178
179
180 .data
181 .globl version_string
182
183version_string:
184 .ascii U_BOOT_VERSION
185 .ascii " (", __DATE__, " - ", __TIME__, ")"
186 .ascii CONFIG_IDENT_STRING, "\0"