2 * (C) Copyright 2004, Psyent Corporation <www.psyent.com>
3 * Scott McNutt <smcnutt@psyent.com>
5 * See file CREDITS for list of people who contributed to this
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.
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.
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,
28 /*************************************************************************
30 ************************************************************************/
36 /* ICACHE INIT -- only the icache line at the reset address
37 * is invalidated at reset. So the init must stay within
38 * the cache line size (8 words). If GERMS is used, we'll
39 * just be invalidating the cache a second time. If cache
40 * is not implemented initi behaves as nop.
42 ori r4, r0, %lo(CONFIG_SYS_ICACHELINE_SIZE)
43 movhi r5, %hi(CONFIG_SYS_ICACHE_SIZE)
44 ori r5, r5, %lo(CONFIG_SYS_ICACHE_SIZE)
49 br _except_end /* Skip the tramp */
51 /* EXCEPTION TRAMPOLINE -- the following gets copied
52 * to the exception address (below), but is otherwise at the
53 * default exception vector offset (0x0020).
56 movhi et, %hi(_exception)
57 ori et, et, %lo(_exception)
61 /* INTERRUPTS -- for now, all interrupts masked and globally
64 wrctl status, r0 /* Disable interrupts */
65 wrctl ienable, r0 /* All disabled */
67 /* DCACHE INIT -- if dcache not implemented, initd behaves as
70 movhi r4, %hi(CONFIG_SYS_DCACHELINE_SIZE)
71 ori r4, r4, %lo(CONFIG_SYS_DCACHELINE_SIZE)
72 movhi r5, %hi(CONFIG_SYS_DCACHE_SIZE)
73 ori r5, r5, %lo(CONFIG_SYS_DCACHE_SIZE)
79 /* RELOCATE CODE, DATA & COMMAND TABLE -- the following code
80 * assumes code, data and the command table are all
81 * contiguous. This lets us relocate everything as a single
82 * block. Make sure the linker script matches this ;-)
85 _cur: movhi r5, %hi(_cur - _start)
86 ori r5, r5, %lo(_cur - _start)
87 sub r4, r4, r5 /* r4 <- cur _start */
90 ori r5, r5, %lo(_start) /* r5 <- linked _start */
94 ori r6, r6, %lo(_edata)
102 /* ZERO BSS/SBSS -- bss and sbss are assumed to be adjacent
103 * and between __bss_start and _end.
105 movhi r5, %hi(__bss_start)
106 ori r5, r5, %lo(__bss_start)
108 ori r6, r6, %lo(_end)
116 /* GLOBAL POINTER -- the global pointer is used to reference
117 * "small data" (see -G switch). The linker script must
118 * provide the gp address.
123 /* JUMP TO RELOC ADDR */
124 movhi r4, %hi(_reloc)
125 ori r4, r4, %lo(_reloc)
129 /* COPY EXCEPTION TRAMPOLINE -- copy the tramp to the
130 * exception address. Define CONFIG_ROM_STUBS to prevent
131 * the copy (e.g. exception in flash or in other
132 * softare/firmware component).
134 #if !defined(CONFIG_ROM_STUBS)
135 movhi r4, %hi(_except_start)
136 ori r4, r4, %lo(_except_start)
137 movhi r5, %hi(_except_end)
138 ori r5, r5, %lo(_except_end)
139 movhi r6, %hi(CONFIG_SYS_EXCEPTION_ADDR)
140 ori r6, r6, %lo(CONFIG_SYS_EXCEPTION_ADDR)
141 beq r4, r6, 7f /* Skip if at proper addr */
151 /* STACK INIT -- zero top two words for call back chain.
153 movhi sp, %hi(CONFIG_SYS_INIT_SP)
154 ori sp, sp, %lo(CONFIG_SYS_INIT_SP)
161 * Call board_init -- never returns
163 movhi r4, %hi(board_init@h)
164 ori r4, r4, %lo(board_init@h)
167 /* NEVER RETURNS -- but branch to the _start just
174 * dly_clks -- Nios2 (like Nios1) doesn't have a timebase in
175 * the core. For simple delay loops, we do our best by counting
176 * instruction cycles.
178 * Instruction performance varies based on the core. For cores
179 * with icache and static/dynamic branch prediction (II/f, II/s):
181 * Normal ALU (e.g. add, cmp, etc): 1 cycle
182 * Branch (correctly predicted, taken): 2 cycles
183 * Negative offset is predicted (II/s).
185 * For cores without icache and no branch prediction (II/e):
187 * Normal ALU (e.g. add, cmp, etc): 6 cycles
188 * Branch (no prediction): 6 cycles
190 * For simplicity, if an instruction cache is implemented we
191 * assume II/f or II/s. Otherwise, we use the II/e.
198 #if (CONFIG_SYS_ICACHE_SIZE > 0)
199 subi r4, r4, 3 /* 3 clocks/loop */
201 subi r4, r4, 12 /* 12 clocks/loop */
207 #if !defined(CONFIG_IDENT_STRING)
208 #define CONFIG_IDENT_STRING ""
211 .globl version_string
214 .ascii U_BOOT_VERSION
215 .ascii " (", __DATE__, " - ", __TIME__, ")"
216 .ascii CONFIG_IDENT_STRING, "\0"