| wdenk | 4a55170 | 2003-10-08 23:26:14 +0000 | [diff] [blame^] | 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 | */ |
| 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 | |
| 96 | 1: 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 */ |
| 107 | 2: |
| 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 |
| 117 | reloc: |
| 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 |
| 132 | 3: 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 */ |
| 141 | 4: |
| 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 | |
| 167 | dly_clks: |
| 168 | lsri %o0, 4 /* cnt/16 */ |
| 169 | |
| 170 | 8: skprnz %o0 |
| 171 | br 9f |
| 172 | subi %o0, 1 /* cnt--, Delay slot */ |
| 173 | br 8b |
| 174 | nop |
| 175 | |
| 176 | 9: lret |
| 177 | nop /* Delay slot */ |
| 178 | |
| 179 | |
| 180 | .data |
| 181 | .globl version_string |
| 182 | |
| 183 | version_string: |
| 184 | .ascii U_BOOT_VERSION |
| 185 | .ascii " (", __DATE__, " - ", __TIME__, ")" |
| 186 | .ascii CONFIG_IDENT_STRING, "\0" |