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/*
* File: start.S
*
* Discription: startup code
*
*/
#include "board_mpc555.h"
#include "mpc555.h"
#include "ppc_asm.h"
.org EXC_OFF_SYS_RESET .globl _start
_start:
/*Set the msr register*/
lis r3, CFG_MSR@h
ori r3, r3, CFG_MSR@l
mtmsr r3
mtspr SRR1, r3
/*Set the bbcmcr register*/
lis r3, CFG_BBCMCR@h
ori r3, r3, CFG_BBCMCR@l
mtspr BBCMCR, r3 /*Set the immr register, 638 is its number*/
lis r3, CFG_IMMR_SET@h
ori r3, r3, CFG_IMMR_SET@l
mtspr IMMR, r3
/* Set up the stack in internal SRAM */
lis r1, __SP_INIT@h
ori r1, r1, __SP_INIT@l
/*Make r0 be 0*/
xor r0, r0, r0
/*Clear final stack frame so that stack backtraces terminate cleanly*/
stwu r0, -4(r1)
stwu r0, -4(r1)
/*initalize some cpu internal memory space registers, r3 is immr*/
bl cpu_init_f /*run low-level board init code, and it's empty right now! (from Flash)
* Maybe we have no external RAM, so check it! If we just have small
* external RAM, what can I do?
*/
/* #if defined(EXTERNAL_RAM)
bl board_init_f
#endif
*/
/*board_init_f will never return, so if we don't execute it, it means that
* we don't need to relocate the code, therefore let's just jump to the entry
* point of OS.
*/
lis r3, jump2OS@h
ori r3, r3, jump2OS@l
mtlr r3
blrl
/*Exception handler*/
.globl _start_of_vectors
_start_of_vectors:
/* Machine Check
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x200
b _start
/* Data Storage
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x300
b _start
/* Instruction Storage
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x400
b _start
/* External Interrupt
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x500
b Interrupt_ESR
/* Alignment
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x600
b _start
/* Program
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x700
b _start
/* Floating Point Unavailable
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x800
b _start
/* Decrementer Interrupt
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x900
stwu r1,-80(r1) #47条指令
stw r0,32(r1) #save working register
mfsrr0 r0 #0=sr0
stw r0,12(1) #memory[1+12]=s0
mfsrr1 r0 #save s1,0=s1
stw r0,16(r1) #memory[1+16]=s1
mtspr 81,r3 #set msr[ee]=0,msr[ri]=1
mflr r0 #get lr
stw r0,8(r1) #save lr
mfxer r0
stw r0,20(r1) #save xer
mfspr r0,CTR #save ctr
stw r0,24(r1)
mfcr r0
stw r0,28(r1) #save cr，以上15
stw r3,36(r1) #save r3-12
stw r4,40(r1)
stw r5,44(r1)
stw r6,48(r1)
stw r7,52(r1)
stw r8,56(r1)
stw r9,60(r1)
stw 10,64(r1)
stw r11,68(r1)
stw r12,72(r1)
lis r4, OSTimeTick@h #跳转到节拍处理函数
ori r4,r4,OSTimeTick@l
blr
lis r5, 0x3 # 0x00030000 ，计数器重置。
addi r5, r5, 0x0D40 # 0x30000 + 0xD40 = 0x30D40 = 200,000
mtdec r5 # Re-load decrementer ，以上16条
lwz 12,72(r1) #restore 12-5，16条指令
lwz r11,68(r1)
lwz 10,64(r1)
lwz r9, 60(r1)
lwz r8, 56(r1)
lwz r7, 52(r1)
lwz r6, 48(r1)
lwz r5, 44(r1)
lwz r0, 28(r1)#restore cr
mtcr r0
lwz r0, 24(r1)#restore xer
mtxer r0
lwz r0, 20(r1)#restore ctr
mtspr CTR, r0
lwz r0, 8(r1)#restore lr
mtlr r0
mtspr 82,r3 # clear recoverable bit,msr[RI]=0=msr[EE]
lwz r0,16(r1) #0=memory[1+16]
mtsrr1 r0 #s1=0
lwz r0,12(r1)
mtsrr0 r0 #restore s0
lwz r4,40(r1) #restore working regster
lwz r3,36(r1)
lwz r0,8(r1)
addi r1,r1,80
rfi
/* System Call
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0xC00
b _start
/* Trace
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0xD00
b _start
/* FP Assist
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0xE00
b _start
/* Performance Monitor
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0xF00
b _start
/* Software Emulation Instruction TLB Miss
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1000
b _start
/* Instruction TLB Miss Data Load TLB Miss
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1100
b _start
/* Data TLB Miss Data Store TLB Miss
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1200
b _start
/* Instruction TLB Error Instruction address breakpoint
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1300
b _start
/* Data TLB Error System management
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1400
b _start
/* Data breakpoint
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1C00
b _start
/* Instruction breakpoint
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1D00
b _start
/* Peripheral breakpoint
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1E00
b _start
/* Non-maskable development port
* Override the behavior by over-writing the handler code in RAM.
*/
.org 0x1F00
b _start
.globl _end_of_vectors
_end_of_vectors:
.=0x2000 /*Maybe other*/
/*
* void relocate_code (addr_sp, des_addr)
*
* This "function" does not return, instead it continues in RAM
* after relocating the code.
*
* r3 = dest
* r4 = src
* r5 = length in bytes
*/
.globl relocate_code
relocate_code:
/*Set new stack pointer in RAM*/
mr r1, r3
/*Save copy of destination address in RAM*/
mr r3, r4
/*Source address*/
lis r4, CFG_FLASH_BASE@h
ori r4, r4, CFG_FLASH_BASE@l
/*???How can I get the length of code??? Assume that r5 is the length.
* Assume that init_end is the end of the code which will be defined in
* the linker file.
*/
lis r5, init_end@h
ori r5, r5, init_end@l
sub r5, r5, r4
/* Now relocate code */
cmplw cr1, r3, r4
addi r0, r5, 3 /*Set the immr register, 638 is its number*/
lis r3, CFG_IMMR_SET@h
ori r3, r3, CFG_IMMR_SET@l
mtspr IMMR, r3
srwi. r0, r0, 2
beq cr1, 4f /* In place copy is not necessary */
beq 4f /* Protect against 0 count */
mtctr r0
bge cr1, 2f
la r8, -4(r4)
la r7, -4(r3)
1: lwzu r0, 4(r8)
stwu r0, 4(r7)
bdnz 1b
b 4f
2: slwi r0, r0, 2
add r8, r4, r0
add r7, r3, r0
3: lwzu r0, -4(r8)
stwu r0, -4(r7)
bdnz 3b
4: sync
isync
/* We are done. Do not return, instead branch to OS initialization, now
* running from RAM.
*/
lis r3, jump2OS@h
ori r3, r3, jump2OS@l
mtlr r3
blrl
/*Interrupt handler, add your code here*/ .globl Interrupt_ESR
Interrupt_ESR:
/*OSTimeTick()*/ .globl OSTimeTick
OSTimeTick:
/*jump to entry point of OS*/ .globl jump2OS
jump2OS:
lis r3, test@ha
addi r3, r3, test@l
mtlr r3
blrl
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