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4a551709 WD |
1 | /* |
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 | |
55 | 0: | |
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 | */ | |
6d0f6bcf JCPV |
74 | pfx %hi(CONFIG_SYS_INIT_SP) |
75 | movi %sp, %lo(CONFIG_SYS_INIT_SP) | |
76 | pfx %xhi(CONFIG_SYS_INIT_SP) | |
77 | movhi %sp, %xlo(CONFIG_SYS_INIT_SP) | |
4a551709 WD |
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 | ||
e4cc71aa WD |
96 | /* No need to move text sections if we're already located |
97 | * at the proper address. | |
98 | */ | |
99 | cmp %g7, %g6 | |
100 | ifs cc_z | |
101 | br reloc | |
102 | nop /* delay slot */ | |
103 | ||
4a551709 WD |
104 | 1: cmp %g7, %g5 |
105 | skps cc_nz | |
106 | br 2f | |
107 | nop /* delay slot */ | |
108 | ||
109 | ld %g0, [%g6] | |
110 | addi %g6, 4 /* src++ */ | |
111 | st [%g7], %g0 | |
112 | addi %g7, 4 /* dst++ */ | |
113 | br 1b | |
114 | nop /* delay slot */ | |
115 | 2: | |
116 | ||
117 | /* | |
118 | * Jump to relocation address | |
119 | */ | |
120 | pfx %hi(reloc@h) | |
121 | movi %g0, %lo(reloc@h) | |
122 | pfx %xhi(reloc@h) | |
123 | movhi %g0, %xlo(reloc@h) | |
124 | jmp %g0 | |
e4cc71aa | 125 | nop /* delay slot */ |
4a551709 WD |
126 | reloc: |
127 | ||
128 | /* | |
129 | * CLEAR BSS | |
130 | */ | |
131 | pfx %hi(__bss_end) | |
132 | movi %g5, %lo(__bss_end) | |
133 | pfx %xhi(__bss_end) | |
134 | movhi %g5, %xlo(__bss_end) /* %g5 <- end address */ | |
135 | pfx %hi(__bss_start) | |
136 | movi %g7, %lo(__bss_start) | |
137 | pfx %xhi(__bss_start) | |
138 | movhi %g7, %xlo(__bss_start) /* %g7 <- end address */ | |
139 | ||
140 | movi %g0, 0 | |
141 | 3: cmp %g7, %g5 | |
142 | skps cc_nz | |
143 | br 4f | |
144 | nop /* delay slot */ | |
145 | ||
146 | st [%g7], %g0 | |
147 | addi %g7, 4 /* (delay slot) dst++ */ | |
148 | br 3b | |
149 | nop /* delay slot */ | |
150 | 4: | |
151 | ||
e4cc71aa WD |
152 | /* |
153 | * INIT VECTOR TABLE | |
154 | */ | |
6d0f6bcf JCPV |
155 | pfx %hi(CONFIG_SYS_VECT_BASE) |
156 | movi %g0, %lo(CONFIG_SYS_VECT_BASE) | |
157 | pfx %xhi(CONFIG_SYS_VECT_BASE) | |
158 | movhi %g0, %xlo(CONFIG_SYS_VECT_BASE) /* dst */ | |
e4cc71aa WD |
159 | mov %l0, %g0 |
160 | ||
161 | pfx %hi(_vectors) | |
162 | movi %g1, %lo(_vectors) | |
163 | pfx %xhi(_vectors) | |
164 | movhi %g1, %xlo(_vectors) /* src */ | |
165 | bgen %g2, 6 /* cnt = 64 */ | |
166 | ||
167 | ldp %g3, [%l0, 3] /* bkpt vector */ | |
168 | ldp %g4, [%l0, 4] /* single step vector */ | |
169 | ||
170 | 5: ld %g7, [%g1] | |
171 | addi %g1, 4 /* src++ */ | |
172 | st [%g0], %g7 | |
173 | addi %g0, 4 /* dst++ */ | |
174 | ||
175 | subi %g2, 1 /* cnt-- */ | |
176 | ifrnz %g2 | |
177 | br 5b | |
178 | nop /* delay slot */ | |
179 | ||
180 | #if defined(CONFIG_ROM_STUBS) | |
181 | /* Restore the breakpoint and single step exception | |
182 | * vectors to their original values. | |
183 | */ | |
184 | stp [%l0,3], %g3 /* breakpoint */ | |
185 | stp [%l0,4], %g4 /* single step */ | |
186 | #endif | |
187 | ||
188 | /* For debug startup convenience ... software breakpoints | |
189 | * set prior to this point may not succeed ;-) | |
190 | */ | |
191 | .global __start | |
192 | __start: | |
193 | ||
4a551709 WD |
194 | /* |
195 | * Call board_init -- never returns | |
196 | */ | |
197 | pfx %hi(board_init@h) | |
198 | movi %g1, %lo(board_init@h) | |
199 | pfx %xhi(board_init@h) | |
200 | movhi %g1, %xlo(board_init@h) | |
201 | call %g1 | |
202 | nop /* Delaly slot */ | |
203 | /* NEVER RETURNS */ | |
204 | ||
205 | /* | |
206 | * dly_clks -- Nios doesn't have a time/clk reference for simple | |
207 | * delay loops, so we do our best by counting instruction cycles. | |
208 | * A control register that counts system clock cycles would be | |
209 | * a handy feature -- hint for Altera ;-) | |
210 | */ | |
53677ef1 | 211 | .globl dly_clks |
4a551709 WD |
212 | /* Each loop is 4 instructions as delay slot is always |
213 | * executed. Each instruction is approximately 4 clocks | |
214 | * (according to some lame info from Altera). So ... | |
215 | * ... each loop is about 16 clocks. | |
216 | */ | |
217 | ||
218 | dly_clks: | |
219 | lsri %o0, 4 /* cnt/16 */ | |
220 | ||
221 | 8: skprnz %o0 | |
222 | br 9f | |
223 | subi %o0, 1 /* cnt--, Delay slot */ | |
224 | br 8b | |
225 | nop | |
226 | ||
227 | 9: lret | |
228 | nop /* Delay slot */ | |
229 | ||
230 | ||
231 | .data | |
232 | .globl version_string | |
233 | ||
234 | version_string: | |
235 | .ascii U_BOOT_VERSION | |
236 | .ascii " (", __DATE__, " - ", __TIME__, ")" | |
237 | .ascii CONFIG_IDENT_STRING, "\0" |