;//2.根据工作频率设置pll
;这里介绍一下计算公式
;//Fpllo=(m*Fin)/(p*2^s)
;//m=Mdiv+8,p=Pdiv+2,s=Sdiv
;The proper range of P and M: 1<=P<=62, 1<=M<=248
;Fpllo必须大于20Mhz小于66Mhz
;Fpllo*2^s必须小于170Mhz
;如下面的PLLCON设定中的M_div P_div S_div是取自option.h中
;#elif (MCLK==40000000)
;#define PLL_M (0x48)
;#define PLL_P (0x3)
;#define PLL_S (0x2)
;所以m=Mdiv+8=80,p=Pdiv+2=5,s=Sdiv=2
;硬件使用晶振为10Mhz,即Fin=10Mhz
;Fpllo=80*10/5*2^2=40Mhz
;To reduce PLL lock time, adjust the LOCKTIME register.
ldr r0,=LOCKTIME
ldr r1,=0xffffff
str r1,[r0]
;//设置PLL的重置延迟
[ PLL_ON_START
; Added for confirm clock divide. for 2440.
; Setting value Fclk:Hclk:Pclk
ldr r0,=CLKdivN
ldr r1,=CLKdiv_VAL ; 0=1:1:1, 1=1:1:2, 2=1:2:2, 3=1:2:4, 4=1:4:4, 5=1:4:8, 6=1:3:3, 7=1:3:6.
str r1,][r0] ;//数据表示分频数
;//Configure UPLL Fin=12.0MHz UFout=48MHz
ldr r0,=UPLLCON
ldr r1,=((U_Mdiv<12)+(U_Pdiv<4)+U_Sdiv) ;//USB PLL CONFIG
str r1,[r0]
nop ;// Caution: After UPLL setting, at least 7-clocks delay must be inserted for setting hardware be completed.
nop
nop
nop
nop
nop
nop
;//Configure MPLL Fin=12.0MHz MFout=304.8MHz
ldr r0,=MPLLCON
ldr r1,=((M_Mdiv<12)+(M_Pdiv<4)+M_Sdiv)
str r1,[r0]
]
;//Check if the boot is caused by the wake-up from SLEEP mode.
ldr r1,=GSTATUS2
ldr r0,[r1]
tst r0,#0x2 ;test if bit[1] is 1 or 0 0->C=1
; 1->C=0
;In case of the wake-up from SLEEP mode, go to SLEEP_WAKEUP handler.
bne WAKEUP_SLEEP ;C=0,jump
EXPORT StartPointAfterSleepWakeUp
StartPointAfterSleepWakeUp
;//3.置存储相关寄存器的程序
;这是设置SDRAM,flash ROM 存储器连接和工作时序的程序,片选定义的程序
;SMRDATA map在下面的程序中定义
;SMRDATA中涉及的值请参考memcfg.s程序
;具体寄存器各位含义请参考s3c44b0 spec
;Set memory control registers
ldr r0,=SMRDATA
ldr r1,=BWSCON ;BWSCON Address
add r2, r0, #52 ;End address of SMRDATA
0
ldr r3, [r0], #4
str r3, [r1], #4
cmp r2, r0
bne %B0
;//set memory registers
;//4.初始化各模式下的栈指针
;Initialize stacks
bl InitStacks
;//5.设置缺省中断处理函数
; Setup IRQ handler
ldr r0,=HandleIRQ ;This routine is needed
ldr r1,=IsrIRQ ;if there isnt subs pc,lr,#4 at 0x18, 0x1c
str r1,[r0]
;//initialize the IRQ 将普通中断判断程序的入口地址给HandleIRQ
;//6.将数据段拷贝到ram中 将零初始化数据段清零 跳入C语言的main函数执行到这步结束bootloader初步引导结束
;If main() is used, the variable initialization will be done in __main().
[ :LNOT:USE_MAIN ;initialized {FALSE}
;Copy and paste RW data/zero initialized data
LDR r0, =|Image$$RO$$Limit| ; Get pointer to ROM data
LDR r1, =|Image$$RW$$Base| ; and RAM copy
LDR r3, =|Image$$ZI$$Base|
;Zero init base => top of initialised data
CMP r0, r1 ; Check that they are different just for debug??????????????????????????
BEQ %F2
1
CMP r1, r3 ; Copy init data
LDRCC r2, ][r0], #4 ;--> LDRCC r2, [r0] + ADD r0, r0, #4
STRCC r2, [r1], #4 ;--> STRCC r2, [r1] + ADD r1, r1, #4
BCC %B1
2
LDR r1, =|Image$$ZI$$Limit| ; Top of zero init segment
MOV r2, #0
3
CMP r3, r1 ; Zero init
STRCC r2, [r3], #4
BCC %B3
]
[ :LNOT:THUMBCODE ;if thumbcode={false} bl main
bl Main ;Dont use main() because ......
b .
]
;//if thumbcod={ture}
[ THUMBCODE ;for start-up code for Thumb mode
orr lr,pc,#1
bx lr
CODE16
bl Main ;Dont use main() because ......
b .
CODE32
]
;function initializing stacks
InitStacks
;Dont use DRAM,such as stmfd,ldmfd......
;SVCstack is initialized before
;Under toolkit ver 2.5, msr cpsr,r1 can be used instead of msr cpsr_cxsf,r1
mrs r0,cpsr
bic r0,r0,#MODEMASK
orr r1,r0,#UNDEFMODE|NOINT
msr cpsr_cxsf,r1 ;UndefMode
ldr sp,=UndefStack ; UndefStack=0x33FF_5C00
orr r1,r0,#ABORTMODE|NOINT
msr cpsr_cxsf,r1 ;AbortMode
ldr sp,=AbortStack ; AbortStack=0x33FF_6000
orr r1,r0,#IRQMODE|NOINT
msr cpsr_cxsf,r1 ;IRQMode
ldr sp,=IRQStack ; IRQStack=0x33FF_7000
orr r1,r0,#FIQMODE|NOINT
