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1 /*
2 *head.S for sdram
3 */
4 .include "2440addr.inc"
5 .include "option.inc"
6 .section .text
7 /*
8 * exception vector table
9 */
10 .global _start
11 _start:
12 b reset
13 b HandleUndef
14 b HandleSWI
15 b HandlePrefetchAbort
16 b HandleDataAbort
17 b HandleNotUsed
18 b HandleIRQ
19 b HandleFIQ
20
21 .global _end
22 _end:
23 .word __bss@定义在sdram.lds中
24 reset:
25 @set cpu to svc32 mode
26 mrs r0, cpsr
27 bic r0, r0, #0x1f
28 orr r0, r0, #0xd3
29 msr cpsr, r0
30
31 @ disable watch dog timer
32 ldr r0, =rWTCON
33 mov r1, #0x0
34 str r1, [r0]
35 @through system clock,you can will see led is fast
36 #if 1
37 @diable all interrupts
38 mov r1, #0xffffffff
39 ldr r0, =rINTMSK
40 str r1, [r0]
41
42 ldr r1, = 0x7fff
43 ldr r0, = rINTSUBMSK
44 str r1, [r0]
45
46 @initialise system clocks
47 ldr r0, =rLOCKTIME
48 ldr r1, =0xffffff
49 str r1, [r0]
50
51 ldr r0, =rCAMDIVN
52 mov r1, #0
53 str r1, [r0]
54
55 ldr r0, =rCLKDIVN
56 ldr r1, =vCLKDIVN_148
57 str r1, [r0]
58
59 mrc p15, 0, r1, c1, c0, 0
60 orr r1, r1, #0xc0000000
61 mcr p15, 0, r1, c1, c0, 0
62
63 ldr r0, = rMPLLCON
64 ldr r1, = vMPLL_400
65 str r1, [r0]
66 #endif
67 bl memsetup
68
69 bl copysram4sdram
70 @jump to ram
71 ldr r1, =on_the_ram
72 add pc, r1, #0
73 nop
74 nop
75 1: b 1b
76
77 on_the_ram:
78 ldr sp,=0x34000000
79 bl start_main
80
81 copysram4sdram:
82 mov r1, #0
83 ldr r2, =0x30000000
84 ldr r3, =_end
85 ldr r3, [r3]
86 sub r3, r3, r2@要得到相对地址
87
88 1: ldr r4, [r1], #4
89 str r4, [r2], #4
90 cmp r1, r3
91 bne 1b
92 mov pc, lr
93
94 memsetup:
95 /*intialize the sdram*/
96 mov r1, #0x48000000
97 adrl r2, mem_cfg_val
98 add r3, r1, #52
99 1: ldr r4, [r2], #4
100 str r4, [r1], #4
101 cmp r1, r3
116 1: b 1b
117
118 HandleNotUsed:
119 1: b 1b
120
121 HandleIRQ:
122 1: b 1b
123
124 HandleFIQ:
125 1: b 1b
126
127 .align 4
128 mem_cfg_val:
129 .word (0+(B1_BWSCON<<4)+(B2_BWSCON<<8)+(B3_BWSCON<<12)+(B4_BWSCON<<16)+(B5
_BWSCON<<20)+(B6_BWSCON<<24)+(B7_BWSCON<<28))
130 .word ((B0_Tacs<<13)+(B0_Tcos<<11)+(B0_Tacc<<8)+(B0_Tcoh<<6)+(B0_Tah<<4)+(
B0_Tacp<<2)+(B0_PMC))
131 .word ((B1_Tacs<<13)+(B1_Tcos<<11)+(B1_Tacc<<8)+(B1_Tcoh<<6)+(B1_Tah<<4)+(
B1_Tacp<<2)+(B1_PMC))
132 .word ((B2_Tacs<<13)+(B2_Tcos<<11)+(B2_Tacc<<8)+(B2_Tcoh<<6)+(B2_Tah<<4)+(
B2_Tacp<<2)+(B2_PMC))
133 .word ((B3_Tacs<<13)+(B3_Tcos<<11)+(B3_Tacc<<8)+(B3_Tcoh<<6)+(B3_Tah<<4)+(
B3_Tacp<<2)+(B3_PMC))
134 .word ((B4_Tacs<<13)+(B4_Tcos<<11)+(B4_Tacc<<8)+(B4_Tcoh<<6)+(B4_Tah<<4)+(
B4_Tacp<<2)+(B4_PMC))
135 .word ((B5_Tacs<<13)+(B5_Tcos<<11)+(B5_Tacc<<8)+(B5_Tcoh<<6)+(B5_Tah<<4)+(
B5_Tacp<<2)+(B5_PMC))
136 .word ((B6_MT<<15)+(B6_Trcd<<2)+(B6_SCAN))
137 .word ((B7_MT<<15)+(B7_Trcd<<2)+(B7_SCAN))
138 .word ((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Trc<<18)+(Tchr<<16)+REFCNT)
139 .word 0x32
140 .word 0x30
141 .word 0x30
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