在2440的uboot和內核中添加nandflash硬件ECC

平臺： tq2440開發板，fl2440開發板
bootload ： u-boot-2010.09
轉載聲明：
http://blog.csdn.net/sonbai/article/details/8737129
借鑑：
http://blog.csdn.net/zhaocj/article/details/6709948
http://blog.chinaunix.net/uid-24063584-id-2642193.html
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一下是以smdk2410爲模板，對代碼稍加改造的基礎上，添加nandflash硬件ECC的功能如下：

第一步：在include/configs/fl2440.h文件中添加三個宏定義，因爲我的nandflash的頁大小是512B的所以下面是的
#define CONFIG_S3C2440_NAND_HWECC
#define CONFIG_SYS_NAND_ECCSIZE 512
#define CONFIG_SYS_NAND_ECCBYTES 4
如果你的是2048就改成2048就行
/*-----------------------------------------------------------------------
* NAND flash settings
*/
#if defined(CONFIG_CMD_NAND)
#define CONFIG_NAND_S3C2410
#define CONFIG_SYS_MAX_NAND_DEVICE 1 /* Max number of NAND devices */
#define CONFIG_SYS_NAND_BASE 0
#define SECTORSIZE 512
#define SECTORSIZE_2K 2048
#define NAND_SECTOR_SIZE SECTORSIZE
#define NAND_SECTOR_SIZE_2K SECTORSIZE_2K
#define NAND_BLOCK_MASK 511
#define NAND_BLOCK_MASK_2K 2047
#define NAND_MAX_CHIPS 1
#define CONFIG_MTD_NAND_VERIFY_WRITE
#define CONFIG_SYS_64BIT_VSPRINTF /* needed for nand_util.c */
#define CONFIG_S3C2440_NAND_HWECC
#define CONFIG_SYS_NAND_ECCSIZE 512
#define CONFIG_SYS_NAND_ECCBYTES 4
#endif /* CONFIG_CMD_NAND */

第二步：在drivers/mtd/nand/s3c2410_nand.c文件中對s3c2410_nand_enable_hwecc函數、s3c2410_nand_calculate_ecc函數和s3c2410_nand_correct_data函數進行修改。
1、該函數的任務就是初始化ECC（即復位ECC），並解鎖main區ECC。
#ifde CONFIG_s3c2410_NAND_HWECC
.........
.........
.........
#elif defined(CONFIG_S3C2440_NAND_HWECC)
void s3c2440_nand_enable_hwecc(struct mtd_info *mtd, int mode)
{
printf("nand_enable_hwecc\n");
struct s3c2410_nand *nand = s3c2410_get_base_nand();
debugX(1, "s3c2410_nand_enable_hwecc(%p, %d)\n", mtd, mode);
writel(readl(&nand->NFCONT) | S3C2410_NFCONT_INITECC & ~S3C2410_NFCONT_MAINECCLOCK, &nand->NFCONT);
}
2、該函數首先鎖定main區ECC，然後讀取寄存器NFMECC0，該寄存器存放着由硬件生成的main區ECC，最後把4個1字節的ECC存放到ecc_code數組內。
static int s3c2410_nand_calculate_ecc(struct mtd_info *mtd, const u_char *dat,
u_char *ecc_code)
{
struct s3c2410_nand *nand = s3c2410_get_base_nand();

writel(read(&nand->NFCONT)|S3C2410_NFCONT_MAINECLLOCK,&nand->NFCONT)

ecc_code[0] = readb(&nand->NFECC);
ecc_code[1] = readb(&nand->NFECC + 1);
ecc_code[2] = readb(&nand->NFECC + 2);
ecc_code[3] = readb(&nand->NFECC + 3);
debugX(1, "s3c2410_nand_calculate_hwecc(%p,): 0x%02x 0x%02x 0x%02x 0x%02x\n",
mtd , ecc_code[0], ecc_code[1], ecc_code[2] ecc_code[3]);

return 0;
}
3、該函數首先把read_ecc數組內的ECC存入寄存器NFMECCD0和寄存器NFMECCD1中，這樣系統就會自動校驗數據，並把狀態放入寄存器NFESTAT0中，然後讀取該寄存器的後4位，當爲0時表示校驗正確；當爲1時表示發生了1位錯誤（該類錯誤可以校正），我們把它校正過來；當爲2和3時表示發生其他類型的錯誤，這類錯誤是無法校正的。
static int s3c2440_nand_correct_data(struct mtd_info *mtd, u_char *dat,
u_char *read_ecc, u_char *calc_ecc)
{
struct s3c2410_nand *nand = s3c2410_get_base_nand();

u32 estat0,err_byte_addr;
int ret = -1;
u8 repaired;

writel((read_ecc[1] << 16) | read_ecc[0],&nand->NFMECCD0);
writel((read_ecc[3] << 16) | read_ecc[2],&nand->NFMECCD1);

/* Read ecc status */
estat0= readl(&nand->NFSTAT);

switch(estat0 & 0x3) {
case 0: /* No error */
ret= 0;
break;

case 1:
/*
* 1 bit error (Correctable)
* (nfestat0 >> 7) & 0x7ff :error byte number
* (nfestat0 >> 4) & 0x7 :error bit number
*
*/
err_byte_addr= (estat0 >> 7) & 0x7ff;
repaired= dat[err_byte_addr] ^ (1 << ((estat0 >> 4) & 0x7));

printf("S3C NAND: 1 bit error detected at byte%ld. "
"Correcting from 0x%02x to0x%02x...OK\n",
err_byte_addr, dat[err_byte_addr],repaired);

dat[err_byte_addr]= repaired;

ret= 1;
break;

case 2: /* Multiple error */
case 3: /* ECC area error */
printf("S3C NAND: ECC uncorrectable errordetected. "
"Not correctable.\n");
ret= -1;
break;
}

return ret;
}
#endif

4、下面是將s3c2440_nand_enable_hwecc函數、s3c2440_nand_calculate_ecc函數和s3c2440_nand_correct_data函數，這三個函數放到
一個結構體中：
#ifdef CONFIG_S3C2410_NAND_HWECC
nand->ecc.hwctl = s3c2410_nand_enable_hwecc;
nand->ecc.calculate = s3c2410_nand_calculate_ecc;
nand->ecc.correct = s3c2410_nand_correct_data;
nand->ecc.mode = NAND_ECC_HW;
nand->ecc.size = CONFIG_SYS_NAND_ECCSIZE;
nand->ecc.bytes = CONFIG_SYS_NAND_ECCBYTES;
#elif defined(CONFIG_S3C2440_NAND_HWECC)
nand->ecc.hwctl = s3c2440_nand_enable_hwecc;
nand->ecc.calculate = s3c2440_nand_calculate_ecc;
nand->ecc.correct = s3c2440_nand_correct_data;
nand->ecc.mode = NAND_ECC_HW;
nand->ecc.size = CONFIG_SYS_NAND_ECCSIZE;
nand->ecc.bytes = CONFIG_SYS_NAND_ECCBYTES;
#else
nand->ecc.mode = NAND_ECC_SOFT;
#endif

這樣我們重新make一下就行了。

內核的ECC配置我上個圖片吧告訴你路徑，你選上就行：