arm9_uboot_分析源码
作者：互联网
/*
* armboot - Startup Code for ARM920 CPU-core
*
* Copyright (c) 2001 Marius Gr鰃er <mag@sysgo.de>
* Copyright (c) 2002 Alex Z黳ke <azu@sysgo.de>
* Copyright (c) 2002 Gary Jennejohn <gj@denx.de>
*
* 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 <config.h>
#include <version.h>
/*
*************************************************************************
*
* Jump vector table as in table 3.1 in [1]
*
*************************************************************************
*/
#define GSTATUS2 (0x560000B4)
#define GSTATUS3 (0x560000B8)
#define GSTATUS4 (0x560000BC)
#define REFRESH (0x48000024)
#define MISCCR (0x56000080)
#define LOCKTIME 0x4C000000 /* R/W, PLL lock time count register */
#define MPLLCON 0x4C000004 /* R/W, MPLL configuration register */
#define UPLLCON 0x4C000008 /* R/W, UPLL configuration register */
#define CLKCON 0x4C00000C /* R/W, Clock generator control reg. */
#define CLKSLOW 0x4C000010 /* R/W, Slow clock control register */
#define CLKDIVN 0x4C000014 /* R/W, Clock divider control */
.globl _start
_start: b reset
ldr pc, _undefined_instruction
ldr pc, _software_interrupt
ldr pc, _prefetch_abort
ldr pc, _data_abort
ldr pc, _not_used
ldr pc, _irq
ldr pc, _fiq
_undefined_instruction: .word undefined_instruction
_software_interrupt: .word software_interrupt
_prefetch_abort: .word prefetch_abort
_data_abort: .word data_abort
_not_used: .word not_used
_irq: .word irq
_fiq: .word fiq
.balignl 16,0xdeadbeef
/*
*************************************************************************
*
* Startup Code (reset vector)
*
* do important init only if we don't start from memory!
* relocate armboot to ram
* setup stack
* jump to second stage
*
*************************************************************************
*/
_TEXT_BASE:
.word TEXT_BASE
.globl _armboot_start
_armboot_start:
.word _start
/*
* These are defined in the board-specific linker script.
*/
.globl _bss_start
_bss_start:
.word __bss_start
.globl _bss_end
_bss_end:
.word _end
.globl FREE_RAM_END
FREE_RAM_END:
.word 0x0badc0de
.globl FREE_RAM_SIZE
FREE_RAM_SIZE:
.word 0x0badc0de
.globl PreLoadedONRAM
PreLoadedONRAM:
.word 0
#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
.word 0x0badc0de
/* IRQ stack memory (calculated at run-time) */
.globl FIQ_STACK_START
FIQ_STACK_START:
.word 0x0badc0de
#endif
/*
* the actual reset code
*/
reset:
/*
* set the cpu to SVC32 mode
*/
mrs r0,cpsr
bic r0,r0,#0x1f
orr r0,r0,#0xd3
msr cpsr,r0
/* turn off the watchdog */
#if defined(CONFIG_S3C2400)
# define pWTCON 0x15300000
# define INTMSK 0x14400008 /* Interupt-Controller base addresses */
# define CLKDIVN 0x14800014 /* clock divisor register */
#elif defined(CONFIG_S3C2410)
# define pWTCON 0x53000000
# define INTMOD 0X4A000004
# define INTMSK 0x4A000008 /* Interupt-Controller base addresses */
# define INTSUBMSK 0x4A00001C
# define CLKDIVN 0x4C000014 /* clock divisor register */
#endif
#if defined(CONFIG_S3C2400) || defined(CONFIG_S3C2410)
ldr r0, =pWTCON
mov r1, #0x0
str r1, [r0]
/*
* mask all IRQs by setting all bits in the INTMR - default
*/
mov r1, #0xffffffff
ldr r0, =INTMSK
str r1, [r0]
# if defined(CONFIG_S3C2410)
ldr r1, =0x3ff
ldr r0, =INTSUBMSK
str r1, [r0]
# endif
#if 0
/* FCLK:HCLK:PCLK = 1:2:4 */
/* default FCLK is 120 MHz ! */
ldr r0, =CLKDIVN
mov r1, #3
str r1, [r0]
#endif
#endif /* CONFIG_S3C2400 || CONFIG_S3C2410 */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
#if 0
/* 这些代码会使用SP,在NAND启动时会破坏片内内存的部分代码
* 导致NAND启动时无法使用休眠-唤醒功能
*/
/* 设置SP指向片内内存 */
ldr sp, =4092
ldr r0, =0x12345678
str r0, [sp]
ldr r1, [sp]
cmp r0, r1
ldrne sp, =0x40000000+4096
bl clock_init
#else
/* 设置时钟, 使用汇编 */
#define S3C2440_MPLL_400MHZ ((0x5c<<12)|(0x01<<4)|(0x01))
#define S3C2440_UPLL_48MHZ ((0x38<<12)|(0x02<<4)|(0x02))
#define S3C2440_CLKDIV (0x05) // | (1<<3)) /* FCLK:HCLK:PCLK = 1:4:8, UCLK = UPLL/2 */
ldr r1, =CLKDIVN
mov r2, #S3C2440_CLKDIV
str r2, [r1]
mrc p15, 0, r1, c1, c0, 0 // read ctrl register
orr r1, r1, #0xc0000000 // Asynchronous
mcr p15, 0, r1, c1, c0, 0 // write ctrl register
ldr r0,=LOCKTIME
ldr r1,=0xffffff
str r1,[r0]
// delay
mov r0, #0x200
1: subs r0, r0, #1
bne 1b
// Configure MPLL
ldr r0,=MPLLCON
ldr r1,=S3C2440_MPLL_400MHZ
str r1,[r0]
// delay
mov r0, #0x200
1: subs r0, r0, #1
bne 1b
//Configure UPLL
ldr r0, =UPLLCON
ldr r1, =S3C2440_UPLL_48MHZ
str r1, [r0]
// delay
mov r0, #0x200
1: subs r0, r0, #1
bne 1b
#endif
#endif
/* 2. 根据 GSTATUS2[1]判断是复位还是唤醒 */
ldr r0, =GSTATUS2
ldr r1, [r0]
tst r1, #(1<<1) /* r1 & (1<<1) */
bne wake_up
/*
* we do sys-critical inits only at reboot,
* not when booting from ram!
*/
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
adr r0, _start /* r0 <- current position of code */
ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
cmp r0, r1 /* don't reloc during debug */
blne cpu_init_crit
#endif
/* Set up the stack */
stack_setup:
ldr r0, _TEXT_BASE /* upper 128 KiB: relocated uboot */
sub r0, r0, #CFG_MALLOC_LEN /* malloc area */
sub r0, r0, #CFG_GBL_DATA_SIZE /* bdinfo */
#ifdef CONFIG_USE_IRQ
sub r0, r0, #(CONFIG_STACKSIZE_IRQ+CONFIG_STACKSIZE_FIQ)
#endif
sub sp, r0, #12 /* leave 3 words for abort-stack */
#ifndef CONFIG_SKIP_RELOCATE_UBOOT
relocate: /* relocate U-Boot to RAM */
adr r0, _start /* r0 <- current position of code */
ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
cmp r0, r1 /* don't reloc during debug */
beq clear_bss
ldr r2, _armboot_start
ldr r3, _bss_start
sub r2, r3, r2 /* r2 <- size of armboot */
#if 1
bl CopyCode2Ram /* r0: source, r1: dest, r2: size */
#else
add r2, r0, r2 /* r2 <- source end address */
copy_loop:
ldmia r0!, {r3-r10} /* copy from source address [r0] */
stmia r1!, {r3-r10} /* copy to target address [r1] */
cmp r0, r2 /* until source end addreee [r2] */
ble copy_loop
#endif
#endif /* CONFIG_SKIP_RELOCATE_UBOOT */
clear_bss:
ldr r0, _bss_start /* find start of bss segment */
ldr r1, _bss_end /* stop here */
mov r2, #0x00000000 /* clear */
clbss_l:str r2, [r0] /* clear loop... */
add r0, r0, #4
cmp r0, r1
ble clbss_l
SetLoadFlag:
/* Set a global flag, PreLoadedONRAM */
adr r0, _start /* r0 <- current position of code */
ldr r1, _TEXT_BASE /* test if we run from flash or RAM */
cmp r0, r1 /* don't reloc during debug */
ldr r2, =PreLoadedONRAM
mov r3, #1
streq r3, [r2]
#if 0
/* try doing this stuff after the relocation */
ldr r0, =pWTCON
mov r1, #0x0
str r1, [r0]
/*
* mask all IRQs by setting all bits in the INTMR - default
*/
mov r1, #0xffffffff
ldr r0, =INTMR
str r1, [r0]
/* FCLK:HCLK:PCLK = 1:2:4 */
/* default FCLK is 120 MHz ! */
ldr r0, =CLKDIVN
mov r1, #3
str r1, [r0]
/* END stuff after relocation */
#endif
ldr pc, _start_armboot
_start_armboot: .word start_armboot
/* 1. 按下按键 */
wake_up:
str r1, [r0] /* clear GSTATUS2 */
/* 3. 设置 MISCCR[19:17]=000b, 以释放SDRAM信号 */
ldr r0, =MISCCR
ldr r1, [r0]
bic r1, r1, #(7<<17)
str r1, [r0]
/* 4. 配置s3c2440的memory controller */
bl cpu_init_crit
/* 5. 等待SDRAM退出self-refresh mode */
mov r0, #1000
1: subs r0, r0, #1
cmp r0, #0
bne 1b
/* 6. 根据GSTATUS[3:4]的值来运行休眠前的函数 */
ldr r0, =GSTATUS3
ldr r1, [r0]
mov pc, r1
/*
*************************************************************************
*
* CPU_init_critical registers
*
* setup important registers
* setup memory timing
*
*************************************************************************
*/
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
cpu_init_crit:
/*
* flush v4 I/D caches
*/
mov r0, #0
mcr p15, 0, r0, c7, c7, 0 /* flush v3/v4 cache */
mcr p15, 0, r0, c8, c7, 0 /* flush v4 TLB */
/*
* disable MMU stuff and caches
*/
mrc p15, 0, r0, c1, c0, 0
bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
orr r0, r0, #0x00000002 @ set bit 2 (A) Align
orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
mcr p15, 0, r0, c1, c0, 0
/*
* before relocating, we have to setup RAM timing
* because memory timing is board-dependend, you will
* find a lowlevel_init.S in your board directory.
*/
mov ip, lr
bl lowlevel_init
mov lr, ip
mov pc, lr
#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
/*
*************************************************************************
*
* Interrupt handling
*
*************************************************************************
*/
@
@ IRQ stack frame.
@
#define S_FRAME_SIZE 72
#define S_OLD_R0 68
#define S_PSR 64
#define S_PC 60
#define S_LR 56
#define S_SP 52
#define S_IP 48
#define S_FP 44
#define S_R10 40
#define S_R9 36
#define S_R8 32
#define S_R7 28
#define S_R6 24
#define S_R5 20
#define S_R4 16
#define S_R3 12
#define S_R2 8
#define S_R1 4
#define S_R0 0
#define MODE_SVC 0x13
#define I_BIT 0x80
/*
* use bad_save_user_regs for abort/prefetch/undef/swi ...
* use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
*/
.macro bad_save_user_regs
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Calling r0-r12
ldr r2, _armboot_start
sub r2, r2, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
sub r2, r2, #(CFG_GBL_DATA_SIZE+8) @ set base 2 words into abort stack
ldmia r2, {r2 - r3} @ get pc, cpsr
add r0, sp, #S_FRAME_SIZE @ restore sp_SVC
add r5, sp, #S_SP
mov r1, lr
stmia r5, {r0 - r3} @ save sp_SVC, lr_SVC, pc, cpsr
mov r0, sp
.endm
.macro irq_save_user_regs
sub sp, sp, #S_FRAME_SIZE
stmia sp, {r0 - r12} @ Calling r0-r12
add r8, sp, #S_PC
stmdb r8, {sp, lr}^ @ Calling SP, LR
str lr, [r8, #0] @ Save calling PC
mrs r6, spsr
str r6, [r8, #4] @ Save CPSR
str r0, [r8, #8] @ Save OLD_R0
mov r0, sp
.endm
.macro irq_restore_user_regs
ldmia sp, {r0 - lr}^ @ Calling r0 - lr
mov r0, r0
ldr lr, [sp, #S_PC] @ Get PC
add sp, sp, #S_FRAME_SIZE
subs pc, lr, #4 @ return & move spsr_svc into cpsr
.endm
.macro get_bad_stack
ldr r13, _armboot_start @ setup our mode stack
sub r13, r13, #(CONFIG_STACKSIZE+CFG_MALLOC_LEN)
sub r13, r13, #(CFG_GBL_DATA_SIZE+8) @ reserved a couple spots in abort stack
str lr, [r13] @ save caller lr / spsr
mrs lr, spsr
str lr, [r13, #4]
mov r13, #MODE_SVC @ prepare SVC-Mode
@ msr spsr_c, r13
msr spsr, r13
mov lr, pc
movs pc, lr
.endm
.macro get_irq_stack @ setup IRQ stack
ldr sp, IRQ_STACK_START
.endm
.macro get_fiq_stack @ setup FIQ stack
ldr sp, FIQ_STACK_START
.endm
/*
* exception handlers
*/
.align 5
undefined_instruction:
get_bad_stack
bad_save_user_regs
bl do_undefined_instruction
.align 5
software_interrupt:
get_bad_stack
bad_save_user_regs
bl do_software_interrupt
.align 5
prefetch_abort:
get_bad_stack
bad_save_user_regs
bl do_prefetch_abort
.align 5
data_abort:
get_bad_stack
bad_save_user_regs
bl do_data_abort
.align 5
not_used:
get_bad_stack
bad_save_user_regs
bl do_not_used
@ thisway.diy, 2006.06.24
.globl Launch
.align 4
Launch:
mov r7, r0
@ diable interrupt
@ disable watch dog timer
mov r1, #0x53000000
mov r2, #0x0
str r2, [r1]
ldr r1,=INTMSK
ldr r2,=0xffffffff @ all interrupt disable
str r2,[r1]
ldr r1,=INTSUBMSK
ldr r2,=0x7ff @ all sub interrupt disable
str r2,[r1]
ldr r1, = INTMOD
mov r2, #0x0 @ set all interrupt as IRQ (not FIQ)
str r2, [r1]
@
mov ip, #0
mcr p15, 0, ip, c13, c0, 0 @ /* zero PID */
mcr p15, 0, ip, c7, c7, 0 @ /* invalidate I,D caches */
mcr p15, 0, ip, c7, c10, 4 @ /* drain write buffer */
mcr p15, 0, ip, c8, c7, 0 @ /* invalidate I,D TLBs */
mrc p15, 0, ip, c1, c0, 0 @ /* get control register */
bic ip, ip, #0x0001 @ /* disable MMU */
mcr p15, 0, ip, c1, c0, 0 @ /* write control register */
@ MMU_EnableICache
@mrc p15,0,r1,c1,c0,0
@orr r1,r1,#(1<<12)
@mcr p15,0,r1,c1,c0,0
@ clear SDRAM: the end of free mem(has wince on it now) to the end of SDRAM
ldr r3, FREE_RAM_END
ldr r4, =PHYS_SDRAM_1+PHYS_SDRAM_1_SIZE @ must clear all the memory unused to zero
mov r5, #0
ldr r1, _armboot_start
ldr r2, =On_Steppingstone
sub r2, r2, r1
mov pc, r2
On_Steppingstone:
2: stmia r3!, {r5}
cmp r3, r4
bne 2b
@ set sp = 0 on sys mode
mov sp, #0
@ add by thisway.diy 2006.06.26, switch to SVC mode
msr cpsr_c, #0xdf @ set the I-bit = 1, diable the IRQ interrupt
msr cpsr_c, #0xd3 @ set the I-bit = 1, diable the IRQ interrupt
ldr sp, =0x31ff5800
nop
nop
nop
nop
mov pc, r7 @ Jump to PhysicalAddress
nop
mov pc, lr
#ifdef CONFIG_USE_IRQ
.align 5
irq:
/* add by www.100ask.net to use IRQ for USB and DMA */
sub lr, lr, #4 @ the return address
ldr sp, IRQ_STACK_START @ the stack for irq
stmdb sp!, { r0-r12,lr } @ save registers
ldr lr, =int_return @ set the return addr
ldr pc, =IRQ_Handle @ call the isr
int_return:
ldmia sp!, { r0-r12,pc }^ @ return from interrupt
.align 5
fiq:
get_fiq_stack
/* someone ought to write a more effiction fiq_save_user_regs */
irq_save_user_regs
bl do_fiq
irq_restore_user_regs
#else
.align 5
irq:
get_bad_stack
bad_save_user_regs
bl do_irq
.align 5
fiq:
get_bad_stack
bad_save_user_regs
bl do_fiq
#endif
以上就是boot第一阶段：
1.硬件设备初始化：将CPU设为SVC模式，关闭开门狗，设置时钟，关闭MMU,Cache
2.准备ram:设置存储控制器
3.复制boot的第二阶段的代码到ram
4.设置好栈
5.跳转到第二阶段的C入口:先清理bss段，再调用arm_lib/board.c的start_armboot函数进入第二阶段
第二阶段：
1.初始化本阶段用到的硬件：改变时钟，配置串口等
2.检测内存映射：板子的内存其实地址和大小
3.uboot命令的格式
4.为内核设置启动参数：对于arm架构，通过lib_arm/armlinux.c的do_bootm_linux函数来启动内核，这个函数设置标记列表，最后通过
theKernel (0, bd->bi_arch_number, bd->bi_boot_params);调用内核下图为uboot内存使用情况
辨别是否从nor启动：
int bBootFrmNORFlash(void)
{
volatile unsigned int *pdw = (volatile unsigned int *)0;
unsigned int dwVal;
/*
* 无论是从NOR Flash还是从NAND Flash启动，
* 地址0处为指令"b Reset", 机器码为0xEA00000B，
* 对于从NAND Flash启动的情况，其开始4KB的代码会复制到CPU内部4K内存中，
* 对于从NOR Flash启动的情况，NOR Flash的开始地址即为0。
* 对于NOR Flash，必须通过一定的命令序列才能写数据，
* 所以可以根据这点差别来分辨是从NAND Flash还是NOR Flash启动:
* 向地址0写入一个数据，然后读出来，如果没有改变的话就是NOR Flash
*/
dwVal = *pdw;
*pdw = 0x12345678;
if (*pdw != 0x12345678)
{
return 1;
}
else
{
*pdw = dwVal;
return 0;
}
}
标签：uboot,r1,arm9,word,ldr,源码,r0,start,define 来源： https://www.cnblogs.com/lzd626/p/11545579.html