| paul@8 | 1 | /* |
| paul@63 | 2 | * Initialisation code for the stage 2 payload. |
| paul@63 | 3 | * |
| paul@63 | 4 | * Copyright 2009 (C) Qi Hardware Inc. |
| paul@63 | 5 | * Author: Wolfgang Spraul <wolfgang@sharism.cc> |
| paul@63 | 6 | * |
| paul@87 | 7 | * Copyright (C) 2015, 2016 Paul Boddie <paul@boddie.org.uk> |
| paul@8 | 8 | * |
| paul@63 | 9 | * This program is free software: you can redistribute it and/or modify |
| paul@63 | 10 | * it under the terms of the GNU General Public License as published by |
| paul@63 | 11 | * the Free Software Foundation, either version 3 of the License, or |
| paul@63 | 12 | * (at your option) any later version. |
| paul@63 | 13 | * |
| paul@63 | 14 | * This program is distributed in the hope that it will be useful, |
| paul@63 | 15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| paul@63 | 16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| paul@63 | 17 | * GNU General Public License for more details. |
| paul@63 | 18 | * |
| paul@63 | 19 | * You should have received a copy of the GNU General Public License |
| paul@63 | 20 | * along with this program. If not, see <http://www.gnu.org/licenses/>. |
| paul@8 | 21 | */ |
| paul@8 | 22 | |
| paul@184 | 23 | #include "mips.h" |
| paul@73 | 24 | #include "sdram.h" |
| paul@73 | 25 | |
| paul@68 | 26 | .text |
| paul@68 | 27 | .extern c_main |
| paul@141 | 28 | .extern _tlb_entry |
| paul@141 | 29 | .extern _exc_entry |
| paul@68 | 30 | .extern _irq_entry |
| paul@68 | 31 | .extern _end_entries |
| paul@128 | 32 | .extern _got_start |
| paul@128 | 33 | .extern _got_end |
| paul@128 | 34 | .extern _got_copy_start |
| paul@68 | 35 | .globl _start |
| paul@68 | 36 | .set noreorder |
| paul@68 | 37 | |
| paul@8 | 38 | _start: |
| paul@167 | 39 | b real_start |
| paul@87 | 40 | nop |
| paul@87 | 41 | |
| paul@87 | 42 | /* Apparently reserved region which, if used, breaks the USB Boot process. */ |
| paul@87 | 43 | |
| paul@167 | 44 | .word 0 |
| paul@167 | 45 | .word 0 |
| paul@167 | 46 | .word 0 |
| paul@167 | 47 | .word 0 |
| paul@167 | 48 | .word 0 |
| paul@167 | 49 | .word 0 |
| paul@167 | 50 | .word 0 |
| paul@167 | 51 | .word 0 |
| paul@87 | 52 | |
| paul@87 | 53 | real_start: |
| paul@86 | 54 | /* Initialise the stack. */ |
| paul@68 | 55 | |
| paul@68 | 56 | la $sp, 0x80080000 |
| paul@68 | 57 | |
| paul@69 | 58 | /* Initialise the globals pointer. */ |
| paul@69 | 59 | |
| paul@69 | 60 | lui $gp, %hi(_GLOBAL_OFFSET_TABLE_) |
| paul@69 | 61 | ori $gp, $gp, %lo(_GLOBAL_OFFSET_TABLE_) |
| paul@69 | 62 | |
| paul@75 | 63 | move $k0, $ra |
| paul@75 | 64 | |
| paul@114 | 65 | /* Copy TLB handling instructions. */ |
| paul@114 | 66 | |
| paul@114 | 67 | la $t0, _tlb_entry /* start */ |
| paul@114 | 68 | li $t1, 0x80000000 |
| paul@141 | 69 | la $t2, _exc_entry /* end */ |
| paul@141 | 70 | jal _copy |
| paul@141 | 71 | nop |
| paul@141 | 72 | |
| paul@141 | 73 | /* Copy exception handling instructions. */ |
| paul@141 | 74 | |
| paul@141 | 75 | la $t0, _exc_entry /* start */ |
| paul@141 | 76 | li $t1, 0x80000180 |
| paul@114 | 77 | la $t2, _irq_entry /* end */ |
| paul@114 | 78 | jal _copy |
| paul@114 | 79 | nop |
| paul@114 | 80 | |
| paul@68 | 81 | /* Copy IRQ handling instructions. */ |
| paul@8 | 82 | |
| paul@86 | 83 | la $t0, _irq_entry /* start */ |
| paul@68 | 84 | li $t1, 0x80000200 |
| paul@69 | 85 | la $t2, _end_entries /* end */ |
| paul@75 | 86 | jal _copy |
| paul@75 | 87 | nop |
| paul@75 | 88 | |
| paul@128 | 89 | /* Copy the offset table for user mode programs. */ |
| paul@128 | 90 | |
| paul@128 | 91 | la $t0, _got_start /* start */ |
| paul@128 | 92 | la $t1, _got_copy_start |
| paul@128 | 93 | la $t2, _got_end /* end */ |
| paul@128 | 94 | li $t3, 0x80000000 /* adjustment */ |
| paul@128 | 95 | jal _copy_adjust |
| paul@128 | 96 | nop |
| paul@128 | 97 | |
| paul@75 | 98 | move $ra, $k0 |
| paul@68 | 99 | |
| paul@73 | 100 | /* Enable caching. */ |
| paul@68 | 101 | |
| paul@73 | 102 | li $t0, CONFIG_CM_CACHABLE_NONCOHERENT |
| paul@184 | 103 | mtc0 $t0, CP0_CONFIG |
| paul@68 | 104 | nop |
| paul@68 | 105 | |
| paul@68 | 106 | /* Start the program. */ |
| paul@68 | 107 | |
| paul@122 | 108 | la $t9, c_main /* load the address of the routine */ |
| paul@68 | 109 | j c_main |
| paul@68 | 110 | nop |
| paul@68 | 111 | |
| paul@75 | 112 | _copy: |
| paul@75 | 113 | /* Copy via $t3 the region from $t0 to $t2 into $t1. */ |
| paul@75 | 114 | |
| paul@75 | 115 | lw $t3, 0($t0) |
| paul@75 | 116 | addiu $t0, $t0, 4 |
| paul@75 | 117 | sw $t3, 0($t1) |
| paul@75 | 118 | bne $t0, $t2, _copy |
| paul@75 | 119 | addiu $t1, $t1, 4 /* executed in delay slot before branch */ |
| paul@159 | 120 | jr $ra |
| paul@75 | 121 | nop |
| paul@75 | 122 | |
| paul@128 | 123 | _copy_adjust: |
| paul@128 | 124 | /* Copy via $t4 the region from $t0 to $t2 into $t1, adjusting by $t3. */ |
| paul@128 | 125 | |
| paul@128 | 126 | lw $t4, 0($t0) |
| paul@128 | 127 | addiu $t0, $t0, 4 |
| paul@128 | 128 | subu $t4, $t4, $t3 |
| paul@128 | 129 | sw $t4, 0($t1) |
| paul@128 | 130 | bne $t0, $t2, _copy_adjust |
| paul@128 | 131 | addiu $t1, $t1, 4 /* executed in delay slot before branch */ |
| paul@159 | 132 | jr $ra |
| paul@128 | 133 | nop |
| paul@128 | 134 | |
| paul@68 | 135 | .set reorder |
