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Diffstat (limited to 'arch/microblaze/cpu/start.S')
| -rw-r--r-- | arch/microblaze/cpu/start.S | 192 |
1 files changed, 192 insertions, 0 deletions
diff --git a/arch/microblaze/cpu/start.S b/arch/microblaze/cpu/start.S new file mode 100644 index 0000000..3da711d --- /dev/null +++ b/arch/microblaze/cpu/start.S @@ -0,0 +1,192 @@ +/* + * (C) Copyright 2007 Michal Simek + * (C) Copyright 2004 Atmark Techno, Inc. + * + * Michal SIMEK <monstr@monstr.eu> + * Yasushi SHOJI <yashi@atmark-techno.com> + * + * See file CREDITS for list of people who contributed to this + * project. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation; either version 2 of + * the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, + * MA 02111-1307 USA + */ + +#include <asm-offsets.h> +#include <config.h> + + .text + .global _start +_start: + /* + * reserve registers: + * r10: Stores little/big endian offset for vectors + * r2: Stores imm opcode + * r3: Stores brai opcode + */ + + mts rmsr, r0 /* disable cache */ + addi r1, r0, CONFIG_SYS_INIT_SP_OFFSET + addi r1, r1, -4 /* Decrement SP to top of memory */ + + /* Find-out if u-boot is running on BIG/LITTLE endian platform + * There are some steps which is necessary to keep in mind: + * 1. Setup offset value to r6 + * 2. Store word offset value to address 0x0 + * 3. Load just byte from address 0x0 + * 4a) LITTLE endian - r10 contains 0x2 because it is the smallest + * value that's why is on address 0x0 + * 4b) BIG endian - r10 contains 0x0 because 0x2 offset is on addr 0x3 + */ + addik r6, r0, 0x2 /* BIG/LITTLE endian offset */ + lwi r7, r0, 0x28 + swi r6, r0, 0x28 /* used first unused MB vector */ + lbui r10, r0, 0x28 /* used first unused MB vector */ + swi r7, r0, 0x28 + + /* add opcode instruction for 32bit jump - 2 instruction imm & brai */ + addi r2, r0, 0xb0000000 /* hex b000 opcode imm */ + addi r3, r0, 0xb8080000 /* hew b808 opcode brai */ + +#ifdef CONFIG_SYS_RESET_ADDRESS + /* reset address */ + swi r2, r0, 0x0 /* reset address - imm opcode */ + swi r3, r0, 0x4 /* reset address - brai opcode */ + + addik r6, r0, CONFIG_SYS_RESET_ADDRESS + sw r6, r1, r0 + lhu r7, r1, r10 + rsubi r8, r10, 0x2 + sh r7, r0, r8 + rsubi r8, r10, 0x6 + sh r6, r0, r8 +#endif + +#ifdef CONFIG_SYS_USR_EXCEP + /* user_vector_exception */ + swi r2, r0, 0x8 /* user vector exception - imm opcode */ + swi r3, r0, 0xC /* user vector exception - brai opcode */ + + addik r6, r0, _exception_handler + sw r6, r1, r0 + /* + * BIG ENDIAN memory map for user exception + * 0x8: 0xB000XXXX + * 0xC: 0xB808XXXX + * + * then it is necessary to count address for storing the most significant + * 16bits from _exception_handler address and copy it to + * 0xa address. Big endian use offset in r10=0 that's why is it just + * 0xa address. The same is done for the least significant 16 bits + * for 0xe address. + * + * LITTLE ENDIAN memory map for user exception + * 0x8: 0xXXXX00B0 + * 0xC: 0xXXXX08B8 + * + * Offset is for little endian setup to 0x2. rsubi instruction decrease + * address value to ensure that points to proper place which is + * 0x8 for the most significant 16 bits and + * 0xC for the least significant 16 bits + */ + lhu r7, r1, r10 + rsubi r8, r10, 0xa + sh r7, r0, r8 + rsubi r8, r10, 0xe + sh r6, r0, r8 +#endif + + /* interrupt_handler */ + swi r2, r0, 0x10 /* interrupt - imm opcode */ + swi r3, r0, 0x14 /* interrupt - brai opcode */ + + addik r6, r0, _interrupt_handler + sw r6, r1, r0 + lhu r7, r1, r10 + rsubi r8, r10, 0x12 + sh r7, r0, r8 + rsubi r8, r10, 0x16 + sh r6, r0, r8 + + /* hardware exception */ + swi r2, r0, 0x20 /* hardware exception - imm opcode */ + swi r3, r0, 0x24 /* hardware exception - brai opcode */ + + addik r6, r0, _hw_exception_handler + sw r6, r1, r0 + lhu r7, r1, r10 + rsubi r8, r10, 0x22 + sh r7, r0, r8 + rsubi r8, r10, 0x26 + sh r6, r0, r8 + + /* Flush cache before enable cache */ + addik r5, r0, 0 + addik r6, r0, XILINX_DCACHE_BYTE_SIZE +flush: bralid r15, flush_cache + nop + + /* enable instruction and data cache */ + mfs r12, rmsr + ori r12, r12, 0xa0 + mts rmsr, r12 + +clear_bss: + /* clear BSS segments */ + addi r5, r0, __bss_start + addi r4, r0, __bss_end + cmp r6, r5, r4 + beqi r6, 3f +2: + swi r0, r5, 0 /* write zero to loc */ + addi r5, r5, 4 /* increment to next loc */ + cmp r6, r5, r4 /* check if we have reach the end */ + bnei r6, 2b +3: /* jumping to board_init */ + brai board_init_f +1: bri 1b + +/* + * Read 16bit little endian + */ + .text + .global in16 + .ent in16 + .align 2 +in16: lhu r3, r0, r5 + bslli r4, r3, 8 + bsrli r3, r3, 8 + andi r4, r4, 0xffff + or r3, r3, r4 + rtsd r15, 8 + sext16 r3, r3 + .end in16 + +/* + * Write 16bit little endian + * first parameter(r5) - address, second(r6) - short value + */ + .text + .global out16 + .ent out16 + .align 2 +out16: bslli r3, r6, 8 + bsrli r6, r6, 8 + andi r3, r3, 0xffff + or r3, r3, r6 + sh r3, r0, r5 + rtsd r15, 8 + or r0, r0, r0 + .end out16 |
