e06ca69b2f
via xmodem to the DBGU port when the AT91 comes up in recovery mode. The recovery loader will then load your program via xmodem into SDRAM at 1MB which can do its things. It needs to be tweaked to the specific board one is using, but it fits in < 1kB (all of Atmel's ARM products have at least 8kb of SRAM that I can tell, so this should work for them all). Parts of this code were provided by Kwikbyte with copyright specifically disclaimed. I heavily modified it to act as a recovery loader (before it was a bootstrap loader) and to optimize for size (before I started the size was closer to 8k). Bootstrap loaders for SPI and IIC to follow.
106 lines
3.3 KiB
ArmAsm
106 lines
3.3 KiB
ArmAsm
/*-
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* Copyright (c) 2006 M. Warner Losh. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* This software is derived from code provided by Kwikbyte with the
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* following information:
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*
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* Initialization for C-environment and basic operation. Adapted from
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* ATMEL cstartup.s.
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*
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* No warranty, expressed or implied, is included with this software. It is
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* provided "AS IS" and no warranty of any kind including statutory or aspects
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* relating to merchantability or fitness for any purpose is provided. All
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* intellectual property rights of others is maintained with the respective
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* owners. This software is not copyrighted and is intended for reference
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* only.
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*
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* $FreeBSD$
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*/
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.equ ARM_MODE_USER, 0x10
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.equ ARM_MODE_FIQ, 0x11
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.equ ARM_MODE_IRQ, 0x12
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.equ ARM_MODE_SVC, 0x13
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.equ ARM_MODE_ABORT, 0x17
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.equ ARM_MODE_UNDEF, 0x1B
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.equ ARM_MODE_SYS, 0x1F
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.equ I_BIT, 0x80
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.equ F_BIT, 0x40
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.equ T_BIT, 0x20
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/*
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* Stack definitions
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*
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* Start near top of internal RAM.
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*/
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.equ END_INT_SRAM, 0x4000
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.equ SVC_STACK_START, (END_INT_SRAM - 0x4)
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.equ SVC_STACK_USE, 0x21800000
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start:
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/* vectors - must reside at address 0 */
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/* the format of this table is defined in the datasheet */
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B InitReset @; reset
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undefvec:
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B undefvec @; Undefined Instruction
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swivec:
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B swivec @; Software Interrupt
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pabtvec:
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B pabtvec @; Prefetch Abort
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dabtvec:
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B dabtvec @; Data Abort
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rsvdvec:
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B rsvdvec
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irqvec:
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ldr pc, [pc,#-0xF20] @; IRQ : read the AIC
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fiqvec:
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B fiqvec @; FIQ
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InitReset:
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/* Set stack and init for SVC */
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ldr r1, = SVC_STACK_START
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mov sp, r1 @; Init stack SYS
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msr cpsr_c, #(ARM_MODE_SVC | I_BIT | F_BIT)
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mov sp, r1 @ ; Init stack SYS
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/* Perform system initialization */
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.extern _init
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bl _init
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/* Start execution at main */
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.extern main
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bl main
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/* main should not return. If it does, spin forever */
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infiniteLoop:
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b infiniteLoop
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