1/* 2 * (C) Copyright 2007 Michal Simek 3 * (C) Copyright 2004 Atmark Techno, Inc. 4 * 5 * Michal SIMEK <monstr@monstr.eu> 6 * Yasushi SHOJI <yashi@atmark-techno.com> 7 * 8 * See file CREDITS for list of people who contributed to this 9 * project. 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License as 13 * published by the Free Software Foundation; either version 2 of 14 * the License, or (at your option) any later version. 15 * 16 * This program is distributed in the hope that it will be useful, 17 * but WITHOUT ANY WARRANTY; without even the implied warranty of 18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 * GNU General Public License for more details. 20 * 21 * You should have received a copy of the GNU General Public License 22 * along with this program; if not, write to the Free Software 23 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, 24 * MA 02111-1307 USA 25 */ 26 27#include <asm-offsets.h> 28#include <config.h> 29 30 .text 31 .global _start 32_start: 33 /* 34 * reserve registers: 35 * r10: Stores little/big endian offset for vectors 36 * r2: Stores imm opcode 37 * r3: Stores brai opcode 38 */ 39 40 mts rmsr, r0 /* disable cache */ 41 addi r1, r0, CONFIG_SYS_INIT_SP_OFFSET 42 addi r1, r1, -4 /* Decrement SP to top of memory */ 43 44 /* Find-out if u-boot is running on BIG/LITTLE endian platform 45 * There are some steps which is necessary to keep in mind: 46 * 1. Setup offset value to r6 47 * 2. Store word offset value to address 0x0 48 * 3. Load just byte from address 0x0 49 * 4a) LITTLE endian - r10 contains 0x2 because it is the smallest 50 * value that's why is on address 0x0 51 * 4b) BIG endian - r10 contains 0x0 because 0x2 offset is on addr 0x3 52 */ 53 addik r6, r0, 0x2 /* BIG/LITTLE endian offset */ 54 lwi r7, r0, 0x28 55 swi r6, r0, 0x28 /* used first unused MB vector */ 56 lbui r10, r0, 0x28 /* used first unused MB vector */ 57 swi r7, r0, 0x28 58 59 /* add opcode instruction for 32bit jump - 2 instruction imm & brai */ 60 addi r2, r0, 0xb0000000 /* hex b000 opcode imm */ 61 addi r3, r0, 0xb8080000 /* hew b808 opcode brai */ 62 63#ifdef CONFIG_SYS_RESET_ADDRESS 64 /* reset address */ 65 swi r2, r0, 0x0 /* reset address - imm opcode */ 66 swi r3, r0, 0x4 /* reset address - brai opcode */ 67 68 addik r6, r0, CONFIG_SYS_RESET_ADDRESS 69 sw r6, r1, r0 70 lhu r7, r1, r10 71 rsubi r8, r10, 0x2 72 sh r7, r0, r8 73 rsubi r8, r10, 0x6 74 sh r6, r0, r8 75#endif 76 77#ifdef CONFIG_SYS_USR_EXCEP 78 /* user_vector_exception */ 79 swi r2, r0, 0x8 /* user vector exception - imm opcode */ 80 swi r3, r0, 0xC /* user vector exception - brai opcode */ 81 82 addik r6, r0, _exception_handler 83 sw r6, r1, r0 84 /* 85 * BIG ENDIAN memory map for user exception 86 * 0x8: 0xB000XXXX 87 * 0xC: 0xB808XXXX 88 * 89 * then it is necessary to count address for storing the most significant 90 * 16bits from _exception_handler address and copy it to 91 * 0xa address. Big endian use offset in r10=0 that's why is it just 92 * 0xa address. The same is done for the least significant 16 bits 93 * for 0xe address. 94 * 95 * LITTLE ENDIAN memory map for user exception 96 * 0x8: 0xXXXX00B0 97 * 0xC: 0xXXXX08B8 98 * 99 * Offset is for little endian setup to 0x2. rsubi instruction decrease 100 * address value to ensure that points to proper place which is 101 * 0x8 for the most significant 16 bits and 102 * 0xC for the least significant 16 bits 103 */ 104 lhu r7, r1, r10 105 rsubi r8, r10, 0xa 106 sh r7, r0, r8 107 rsubi r8, r10, 0xe 108 sh r6, r0, r8 109#endif 110 111 /* interrupt_handler */ 112 swi r2, r0, 0x10 /* interrupt - imm opcode */ 113 swi r3, r0, 0x14 /* interrupt - brai opcode */ 114 115 addik r6, r0, _interrupt_handler 116 sw r6, r1, r0 117 lhu r7, r1, r10 118 rsubi r8, r10, 0x12 119 sh r7, r0, r8 120 rsubi r8, r10, 0x16 121 sh r6, r0, r8 122 123 /* hardware exception */ 124 swi r2, r0, 0x20 /* hardware exception - imm opcode */ 125 swi r3, r0, 0x24 /* hardware exception - brai opcode */ 126 127 addik r6, r0, _hw_exception_handler 128 sw r6, r1, r0 129 lhu r7, r1, r10 130 rsubi r8, r10, 0x22 131 sh r7, r0, r8 132 rsubi r8, r10, 0x26 133 sh r6, r0, r8 134 135 /* enable instruction and data cache */ 136 mfs r12, rmsr 137 ori r12, r12, 0xa0 138 mts rmsr, r12 139 140clear_bss: 141 /* clear BSS segments */ 142 addi r5, r0, __bss_start 143 addi r4, r0, __bss_end 144 cmp r6, r5, r4 145 beqi r6, 3f 1462: 147 swi r0, r5, 0 /* write zero to loc */ 148 addi r5, r5, 4 /* increment to next loc */ 149 cmp r6, r5, r4 /* check if we have reach the end */ 150 bnei r6, 2b 1513: /* jumping to board_init */ 152 brai board_init 1531: bri 1b 154 155/* 156 * Read 16bit little endian 157 */ 158 .text 159 .global in16 160 .ent in16 161 .align 2 162in16: lhu r3, r0, r5 163 bslli r4, r3, 8 164 bsrli r3, r3, 8 165 andi r4, r4, 0xffff 166 or r3, r3, r4 167 rtsd r15, 8 168 sext16 r3, r3 169 .end in16 170 171/* 172 * Write 16bit little endian 173 * first parameter(r5) - address, second(r6) - short value 174 */ 175 .text 176 .global out16 177 .ent out16 178 .align 2 179out16: bslli r3, r6, 8 180 bsrli r6, r6, 8 181 andi r3, r3, 0xffff 182 or r3, r3, r6 183 sh r3, r0, r5 184 rtsd r15, 8 185 or r0, r0, r0 186 .end out16 187