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标题:
TL138 uboot是怎么区分配置两款核心板的
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作者:
Mr.Loser
时间:
2014-9-11 09:33
标题:
TL138 uboot是怎么区分配置两款核心板的
核心板1：DDR2 128M Byte NAND FLASH 4G bit
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核心板2：DDR2 256M Byte NAND FLASH 8G bit
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这两个核心板公共一个uboot，DDR2的配置肯定是不同的，uboot怎么检查到是哪个核心板，然后去执行相应的配置呢？
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是不是通过读NAND FLASH的ID，两款核心板NAND FLASH不同，ID也不同，这样读到了ID就知道是哪个核心板了？
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作者:
2532609929
时间:
2014-9-11 18:55
DDR通过检查最大有效地址来识别容量，具体请看uboot的common/memsize.c文件中的检查代码，也可以看如下：
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/*
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* Check memory range for valid RAM. A simple memory test determines
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* the actually available RAM size between addresses `base' and
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* `base + maxsize'.
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*/
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long get_ram_size(long *base, long maxsize)
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{
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volatile long *addr;
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long save[32];
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long cnt;
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long val;
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long size;
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int i = 0;
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for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
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addr = base + cnt; /* pointer arith! */
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sync ();
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save[i++] = *addr;
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sync ();
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*addr = ~cnt;
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}
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addr = base;
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sync ();
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save
= *addr;
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sync ();
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*addr = 0;
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sync ();
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if ((val = *addr) != 0) {
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/* Restore the original data before leaving the function.
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*/
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sync ();
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*addr = save
;
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for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
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addr = base + cnt;
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sync ();
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*addr = save[--i];
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}
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return (0);
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}
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for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
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addr = base + cnt; /* pointer arith! */
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val = *addr;
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*addr = save[--i];
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if (val != ~cnt) {
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size = cnt * sizeof (long);
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/* Restore the original data before leaving the function.
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*/
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for (cnt <<= 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
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addr = base + cnt;
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*addr = save[--i];
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}
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return (size);
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}
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}
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return (maxsize);
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}
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int dram_init(void)
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{
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/* dram_init must store complete ramsize in gd->ram_size */
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gd->ram_size = get_ram_size(
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(void *)CONFIG_SYS_SDRAM_BASE,
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CONFIG_MAX_RAM_BANK_SIZE);
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return 0;
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}
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FLASH是通过检查FLASH内部的ID识别容量，希望对您有帮助！
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