a.进入汇编函数lowlevel_init(路径:board\samsung\smdk2440\lowlevel_init.S)的lowlevel_init代码段，找到：
SMRDATA: .word (0+(B1_BWSCON<<4)+(B2_BWSCON<<8)+(B3_BWSCON<<12)+(B4_BWSCON<<16)+(B5_BWSCON<<20)+(B6_BWSCON<<24)+(B7_BWSCON<<28)) .word ((B0_Tacs<<13)+(B0_Tcos<<11)+(B0_Tacc<<8)+(B0_Tcoh<<6)+(B0_Tah<<4)+(B0_Tacp<<2)+(B0_PMC)) .word ((B1_Tacs<<13)+(B1_Tcos<<11)+(B1_Tacc<<8)+(B1_Tcoh<<6)+(B1_Tah<<4)+(B1_Tacp<<2)+(B1_PMC)) .word ((B2_Tacs<<13)+(B2_Tcos<<11)+(B2_Tacc<<8)+(B2_Tcoh<<6)+(B2_Tah<<4)+(B2_Tacp<<2)+(B2_PMC)) .word ((B3_Tacs<<13)+(B3_Tcos<<11)+(B3_Tacc<<8)+(B3_Tcoh<<6)+(B3_Tah<<4)+(B3_Tacp<<2)+(B3_PMC)) .word ((B4_Tacs<<13)+(B4_Tcos<<11)+(B4_Tacc<<8)+(B4_Tcoh<<6)+(B4_Tah<<4)+(B4_Tacp<<2)+(B4_PMC)) .word ((B5_Tacs<<13)+(B5_Tcos<<11)+(B5_Tacc<<8)+(B5_Tcoh<<6)+(B5_Tah<<4)+(B5_Tacp<<2)+(B5_PMC)) .word ((B6_MT<<15)+(B6_Trcd<<2)+(B6_SCAN)) .word ((B7_MT<<15)+(B7_Trcd<<2)+(B7_SCAN)) .word ((REFEN<<23)+(TREFMD<<22)+(Trp<<20)+(Trc<<18)+(Tchr<<16)+REFCNT) .word 0x32 .word 0x30 .word 0x30
修改为:
SMRDATA:
.long 0x22011110//BWSCON .long 0x00000700//BANKCON0 .long 0x00000700//BANKCON1 .long 0x00000700//BANKCON2 .long 0x00000700//BANKCON3 .long 0x00000700//BANKCON4 .long 0x00000700//BANKCON5 .long 0x00018005//BANKCON6 .long 0x00018005//BANKCON7 .long 0x008C04F4// REFRESH .long 0x000000B1//BANKSIZE .long 0x00000030//MRSRB6 .long 0x00000030//MRSRB7
至于为什么这么修改，因为手册上就是这么说的......
b.如果此时把uboot.bin烧写到Nor Flash上，启动开发板，是能看到串口有反应了:
U-Boot 2016.11 (May 03 2017 - 20:24:36 +0800) CPUID: 32440001 FCLK: 400 MHz HCLK: 100 MHz PCLK: 50 MHz DRAM: 64 MiB WARNING: Caches not enabled Flash: 0 Bytes NAND: 0 MiB *** Warning - bad CRC , using default environment In: serial Out: serial Err: serial Net: CS8900-0 Error: CS8900-0 address not set. SMDK2440 #
说明时钟和内存应该没问题了、
c.但是，可以看到，现在uboot还是有问题的，但是我们先不管，先让uboot支持NAND启动.
