TQ2440启动代码分析(二)
be valid if the current mode is not SVC mode. LTORG 这段程序的开始使用DATA 伪操作指明SMRDATA 标号处作为一段数据,而非代码。 接下来就用DCD 分配一个字的内存单元,一共13 个字数据。 SMRDATA DATA ; Memory configuration should be optimized for best performance ; The following parameter is not optimized. ; Memory access cycle parameter strategy ; 1) The memory settings is safe parameters even at HCLK=75Mhz. ; 2) SDRAM refresh period is for HCLK<=75Mhz. DCD (0+(B1_BWSCON<4)+(B2_BWSCON<8)+(B3_BWSCON<12)+(B4_BWSCON<16)+(B5_BWSCON<20)+(B6_BWSCON<24)+(B7_BWSCON<28)) DCD ((B0_Tacs<13)+(B0_Tcos<11)+(B0_Tacc<8)+(B0_Tcoh<6)+(B0_Tah<4)+(B0_Tacp<2)+(B0_PMC)) ;GCS0 DCD ((B1_Tacs<13)+(B1_Tcos<11)+(B1_Tacc<8)+(B1_Tcoh<6)+(B1_Tah<4)+(B1_Tacp<2)+(B1_PMC)) ;GCS1 DCD ((B2_Tacs<13)+(B2_Tcos<11)+(B2_Tacc<8)+(B2_Tcoh<6)+(B2_Tah<4)+(B2_Tacp<2)+(B2_PMC)) ;GCS2 DCD ((B3_Tacs<13)+(B3_Tcos<11)+(B3_Tacc<8)+(B3_Tcoh<6)+(B3_Tah<4)+(B3_Tacp<2)+(B3_PMC)) ;GCS3 DCD ((B4_Tacs<13)+(B4_Tcos<11)+(B4_Tacc<8)+(B4_Tcoh<6)+(B4_Tah<4)+(B4_Tacp<2)+(B4_PMC)) ;GCS4 DCD ((B5_Tacs<13)+(B5_Tcos<11)+(B5_Tacc<8)+(B5_Tcoh<6)+(B5_Tah<4)+(B5_Tacp<2)+(B5_PMC)) ;GCS5 DCD ((B6_MT<15)+(B6_Trcd<2)+(B6_SCAN)) ;GCS6 DCD ((B7_MT<15)+(B7_Trcd<2)+(B7_SCAN)) ;GCS7 DCD ((REFEN<23)+(TREFMD<22)+(Trp<20)+(Tsrc<18)+(Tchr<16)+REFCNT) DCD 0x32 ;SCLK power saving mode, BANKSIZE 128M/128M DCD 0x30 ;MRSR6 CL=3clk DCD 0x30 ;MRSR7 CL=3clk BaseOfROM DCD |Image$$RO$$Base| TopOfROM DCD |Image$$RO$$Limit| BaseOfBSS DCD |Image$$RW$$Base| BaseOfZero DCD |Image$$ZI$$Base| EndOfBSS DCD |Image$$ZI$$Limit| ALIGN ;Function for entering power down mode ; 1. SDRAM should be in self-refresh mode. ; 2. All interrupt should be maksked for SDRAM/DRAM self-refresh. ; 3. LCD controller should be disabled for SDRAM/DRAM self-refresh. ; 4. The I-cache may have to be turned on. ; 5. The location of the following code may have not to be changed. ;void EnterPWDN(int CLKCON); EnterPWDN mov r2,r0 ;r2=rCLKCON tst r0,#0x8 ;SLEEP mode? bne ENTER_SLEEP ENTER_STOP ldr r0,=REFRESH ldr r3,[r0] ;r3=rREFRESH mov r1, r3 orr r1, r1, #BIT_SELFREFRESH str r1, [r0] ;Enable SDRAM self-refresh mov r1,#16 ;wait until self-refresh is issued. may not be needed. 0 subs r1,r1,#1 bne %B0 ldr r0,=CLKCON ;enter STOP mode. str r2,[r0] mov r1,#32 0 subs r1,r1,#1 ;1) wait until the STOP mode is in effect. bne %B0 ;2) Or wait here until the CPU&Peripherals will be turned-off ; Entering SLEEP mode, only the reset by wake-up is available. ldr r0,=REFRESH ;exit from SDRAM self refresh mode. str r3,[r0] MOV_PC_LR ENTER_SLEEP ;NOTE. ;1) rGSTATUS3 should have the return address after wake-up from SLEEP mode. ldr r0,=REFRESH ldr r1,[r0] ;r1=rREFRESH orr r1, r1, #BIT_SELFREFRESH str r1, [r0] ;Enable SDRAM self-refresh mov r1,#16 ;Wait until self-refresh is issued,which may not be needed. 0 subs r1,r1,#1 bne %B0 ldr r1,=MISCCR ldr r0,[r1] orr r0,r0,#(7<17) ;Set SCLK0=0, SCLK1=0, SCKE=0. str r0,[r1] ldr r0,=CLKCON ; Enter sleep mode str r2,[r0] b . ;CPU will die here. WAKEUP_SLEEP;从睡眠状态醒过来 ;Release SCLKn after wake-up from the SLEEP mode. ldr r1,=MISCCR ldr r0,[r1] bic r0,r0,#(7<17) ;SCLK0:0->SCLK, SCLK1:0->SCLK, SCKE:0->=SCKE. str r0,[r1] ;Set memory control registers ldr r0,=SMRDATA ;be careful! 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 mov r1,#256 0 subs r1,r1,#1 ;1) wait until the SelfRefresh is released. bne %B0 ldr r1,=GSTATUS3 ;GSTATUS3 has the start address just after SLEEP wake-up ldr r0,[r1] mov pc,r0 ;===================================================================== ; Clock division test ; Assemble code, because VSYNC time is very short ;===================================================================== EXPORT CLKdiv124 EXPORT CLKdiv144 CLKdiv124 ldr r0, = CLKdivN ldr r1, = 0x3 ; 0x3 = 1:2:4 str r1, [r0] ; wait until clock is stable nop nop nop nop nop ldr r0, = REFRESH ldr r1, [r0] bic r1, r1, #0xff bic r1, r1, #(0x7<8) orr r1, r1, #0x470 ; REFCNT135 str r1, [r0] nop nop nop nop nop mov pc, lr CLKdiv144 ldr r0, = CLKdivN ldr r1, = 0x4 ; 0x4 = 1:4:4 str r1, [r0] ; wait until clock is stable nop nop nop nop nop ldr r0, = REFRESH ldr r1, [r0] bic r1, r1, #0xff bic r1, r1, #(0x7<8) orr r1, r1, #0x630 ; REFCNT675 - 1520 str r1, [r0] nop nop nop nop nop mov pc, lr ALIGN;按照一定的规则对齐,^符号相当于伪指令MAP,用于定义一个结构化的内存表的
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