移植u-boot之修改代码支持NandFlash-3.4

本节实现支持nand flash

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修改UBOOT支持NAND FLASH的读写，前面只是支持NAND的方式启动，这是两回事。

1. 修改配置文件，将支持NAND模块

    修改：include/configs/smdk2440.h:

#define CONFIG_CMD_NAND   // 把这句话加上，重新编译，看出错信息，进行修改源码。

编译错误

s3c2410_nand.c: In function 's3c2410_hwcontrol':
s3c2410_nand.c:57: warning: implicit declaration of function 's3c2410_get_base_nand'
s3c2410_nand.c:57: warning: initialization makes pointer from integer without a cast
s3c2410_nand.c:72: error: dereferencing pointer to incomplete type
s3c2410_nand.c:72: error: dereferencing pointer to incomplete type
s3c2410_nand.c:75: error: dereferencing pointer to incomplete type
s3c2410_nand.c:75: error: dereferencing pointer to incomplete type
s3c2410_nand.c: In function 's3c2410_dev_ready':
s3c2410_nand.c:85: warning: initialization makes pointer from integer without a cast
s3c2410_nand.c:87: error: dereferencing pointer to incomplete type
s3c2410_nand.c: In function 'board_nand_init':
s3c2410_nand.c:129: warning: initialization makes pointer from integer without a cast
s3c2410_nand.c:150: error: dereferencing pointer to incomplete type
s3c2410_nand.c:153: error: dereferencing pointer to incomplete type
s3c2410_nand.c:154: error: dereferencing pointer to incomplete type
make[1]: *** [s3c2410_nand.o] Error 1
make[1]: Leaving directory `/work/system/u-boot-2012.04.01/drivers/mtd/nand'
make: *** [drivers/mtd/nand/libnand.o] Error 2

2440与nand flash的交互：

2440内部有nand flash控制器，数据线有8根：
（1）CLE为高电平，数据线上发送的是命令；
（2）ALE为高电平，数据线上发送的是地址；
（3）CLE，ALE为低，表示发送的是数据

2440对于nand flash操作有一类寄存器进行控制，设置。
NFCMD, NFADDR, NFDATA, 还有检测忙信号等。

而NOR flash有类似于内存接口，可以直接访问某个地址。NAND FLASH只能通过发送某些特定的序列，通过IO口的方式读取某个地址的数据。

2. 拷贝现有的NAND文件为板子所用

把drivers\mtd\nand\s3c2410_nand.c复制为s3c2440_nand.c

但是如何将改动的文件 s3c2440_nand.c 编译进内核呢？
修改在该目录下的Makefile文件：

COBJS-$(CONFIG_NAND_KIRKWOOD) += kirkwood_nand.o
COBJS-$(CONFIG_NAND_KMETER1) += kmeter1_nand.o
COBJS-$(CONFIG_NAND_MPC5121_NFC) += mpc5121_nfc.o
COBJS-$(CONFIG_NAND_MXC) += mxc_nand.o
COBJS-$(CONFIG_NAND_MXS) += mxs_nand.o
COBJS-$(CONFIG_NAND_NDFC) += ndfc.o
COBJS-$(CONFIG_NAND_NOMADIK) += nomadik.o
COBJS-$(CONFIG_NAND_S3C2410) += s3c2410_nand.o
COBJS-$(CONFIG_NAND_S3C2440) += s3c2440_nand.o     // 添加这句话，这个宏：CONFIG_NAND_S3C2440 在配置文件 includes\configs\smdk2440.h 中定义
COBJS-$(CONFIG_NAND_S3C64XX) += s3c64xx.o
COBJS-$(CONFIG_NAND_SPEAR) += spr_nand.o
COBJS-$(CONFIG_NAND_OMAP_GPMC) += omap_gpmc.o
COBJS-$(CONFIG_NAND_PLAT) += nand_plat.o

所以在配置文件里应该启用这个宏 CONFIG_NAND_S3C2440

#define CONFIG_CMD_NAND   // 启用NAND

/*
 * NAND configuration
 */
#ifdef CONFIG_CMD_NAND

#ifdef CONFIG_S3C2410

#define CONFIG_NAND_S3C2410
#define CONFIG_SYS_S3C2410_NAND_HWECC

#else // CONFIG_S3C2440配置选项

#define CONFIG_NAND_S3C2440
#define CONFIG_SYS_S3C2440_NAND_HWECC

#endif

#define CONFIG_SYS_MAX_NAND_DEVICE    1
#define CONFIG_SYS_NAND_BASE        0x4E000000

#endif

3. 分析nand flash工作过程

nand_init
    nand_init_chip
        board_nand_init
            设置nand_chip结构体, 提供底层的操作函数
        nand_scan
            nand_scan_ident
                nand_set_defaults
                    chip->select_chip = nand_select_chip;
                    chip->cmdfunc = nand_command;
                    chip->read_byte = busw ? nand_read_byte16 : nand_read_byte;
                    
                nand_get_flash_type
                    chip->select_chip
                    chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
                            nand_command()  // 即可以用来发命令，也可以用来发列地址(页内地址)、行地址(哪一页)
                                chip->cmd_ctrl
                                        s3c2440_hwcontrol
                                
                    chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
                    *maf_id = chip->read_byte(mtd);
                    *dev_id = chip->read_byte(mtd);

4. 修改底层操作函数：s3c2440_nand.c

/*
 * (C) Copyright 2006 OpenMoko, Inc.
 * Author: Harald Welte <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
 * MA 02111-1307 USA
 */

#include <common.h>

#include <nand.h>
#include <asm/arch/s3c24x0_cpu.h>
#include <asm/io.h>

#define S3C2410_NFCONF_EN (1<<15)
#define S3C2410_NFCONF_512BYTE (1<<14)
#define S3C2410_NFCONF_4STEP (1<<13)
#define S3C2410_NFCONF_INITECC (1<<12)
#define S3C2410_NFCONF_nFCE (1<<11)
#define S3C2410_NFCONF_TACLS(x) ((x)<<8)
#define S3C2410_NFCONF_TWRPH0(x) ((x)<<4)
#define S3C2410_NFCONF_TWRPH1(x) ((x)<<0)

#define S3C2410_ADDR_NALE 4
#define S3C2410_ADDR_NCLE 8

#ifdef CONFIG_NAND_SPL

/* in the early stage of NAND flash booting, printf() is not available */
#define printf(fmt, args...)

static void nand_read_buf(struct mtd_info *mtd, u_char *buf, int len)
{
    int i;
    struct nand_chip *this = mtd->priv;

    for (i = 0; i < len; i++)
        buf[i] = readb(this->IO_ADDR_R);
}
#endif



/*
  *
  * ctrl: 表示做什么，选中/取消选中芯片，发命令还是发地址
  *
  * cmd: 命令值或者地址值
  *
  */
static void s3c2440_hwcontrol(struct mtd_info *mtd, int dat, unsigned int ctrl)
{
    struct nand_chip *chip = mtd->priv;
#if 0
    struct s3c2410_nand *nand = s3c2410_get_base_nand();
#else
    // 获取nand flash 控制器的基地址
    struct s3c2440_nand *nand = s3c2440_get_base_nand();
#endif

    if(ctrl & NAND_CLE)
    {
        /* 发命令 */
        writeb(dat, &nand->nfcmd);
    }
    else if(ctrl & NAND_ALE)
    {
        /* 发地址 */
        writeb(dat, &nand->nfaddr);
    }



#if 0
    debug("hwcontrol(): 0x%02x 0x%02x\n", cmd, ctrl);

    if (ctrl & NAND_CTRL_CHANGE) {
        ulong IO_ADDR_W = (ulong)nand;

        if (!(ctrl & NAND_CLE))
            IO_ADDR_W |= S3C2410_ADDR_NCLE;
        if (!(ctrl & NAND_ALE))
            IO_ADDR_W |= S3C2410_ADDR_NALE;

        chip->IO_ADDR_W = (void *)IO_ADDR_W;

        if (ctrl & NAND_NCE) /* 使能选中*/
        {
           #if 0
                writel(readl(&nand->nfconf) & ~S3C2410_NFCONF_nFCE,
                 &nand->nfconf);
           #else
                writel(readl(&nand->nfcont) & ~(1<<1), // nfcont bit1 clear
                 &nand->nfcont);
           #endif
        }
        else /* 取消选中*/
        {
            #if 0
                writel(readl(&nand->nfconf) | S3C2410_NFCONF_nFCE,
                 &nand->nfconf);

            #else
                writel(readl(&nand->nfcont) | (1<<1),
                 &nand->nfcont);

            #endif
        }


#ifdef BOGUS
            writel(readl(&nand->nfconf) | S3C2410_NFCONF_nFCE,
             &nand->nfconf);
#endif /* BOGUS */
    }

    if (cmd != NAND_CMD_NONE)
        writeb(cmd, chip->IO_ADDR_W);
#endif


}

static int s3c2440_dev_ready(struct mtd_info *mtd)
{
    //struct s3c2410_nand *nand = s3c2410_get_base_nand();
    struct s3c2440_nand *nand = s3c2440_get_base_nand();

    debug("dev_ready\n");
    return readl(&nand->nfstat) & 0x01;
}


// 参考已知代码，添加下面的这个函数
static void s3c2440_nand_select(struct mtd_info *mtd, int chipnr)
{
    struct s3c2440_nand *nand = s3c2440_get_base_nand();

    switch (chipnr) {

    case -1: /* 取消选中*/
        nand->nfcont |= (1<<1);
        break;
    case 0: /* 选中*/
        nand->nfcont &=~ (1<<1);
    break;

    default:
        BUG();
    }
}



int board_nand_init(struct nand_chip *nand)
{
    u_int32_t cfg;
    u_int8_t tacls, twrph0, twrph1;
    struct s3c24x0_clock_power *clk_power = s3c24x0_get_base_clock_power();

#if 0 // grant modify
    struct s3c2410_nand *nand_reg = s3c2410_get_base_nand();
#else
    struct s3c2440_nand *nand_reg = s3c2440_get_base_nand();
#endif

    debug("board_nand_init()\n");

    writel(readl(&clk_power->clkcon) | (1 << 4), &clk_power->clkcon);

    /* initialize hardware */
#if defined(CONFIG_S3C24XX_CUSTOM_NAND_TIMING)
    tacls = CONFIG_S3C24XX_TACLS;
    twrph0 = CONFIG_S3C24XX_TWRPH0;
    twrph1 = CONFIG_S3C24XX_TWRPH1;
#else

    // 根据不同的开发板，设置时间参数
    tacls = 4;
    twrph0 = 8;
    twrph1 = 8;
#endif

#if 0
    // 适用于2410

    cfg = S3C2410_NFCONF_EN;
    cfg |= S3C2410_NFCONF_TACLS(tacls - 1);
    cfg |= S3C2410_NFCONF_TWRPH0(twrph0 - 1);
    cfg |= S3C2410_NFCONF_TWRPH1(twrph1 - 1);
#else

    /* 初始化时序 */
    cfg = ((tacls-1) << 12) | ((twrph0-1) << 8) | ((twrph1-1) << 4);
#endif

    writel(cfg, &nand_reg->nfconf);

    /* 增加下面的语句，使能NAND FLASH控制器，初始化ECC, 禁止片选*/
    writel((1<<4) | (1<<1) | (1<<0), &nand_reg->nfcont);


    /* initialize nand_chip data structure */
    nand->IO_ADDR_R = (void *)&nand_reg->nfdata;
    nand->IO_ADDR_W = (void *)&nand_reg->nfdata;

    // nand->select_chip = NULL;
    // 修改为下面的语句
    nand->select_chip = s3c2440_nand_select;  // 增加这个函数 s3c2440_nand_select

    /* read_buf and write_buf are default */
    /* read_byte and write_byte are default */
#ifdef CONFIG_NAND_SPL
    nand->read_buf = nand_read_buf;
#endif

    /* hwcontrol always must be implemented */
    nand->cmd_ctrl = s3c2440_hwcontrol;

    nand->dev_ready = s3c2440_dev_ready;

// ECC的引入是为了解决NAND FLASH的缺陷
#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;
#else
    nand->ecc.mode = NAND_ECC_SOFT;  // 软件ECC模式
#endif

#ifdef CONFIG_S3C2410_NAND_BBT
    nand->options = NAND_USE_FLASH_BBT;
#else
    nand->options = 0;
#endif

    debug("end of nand_init\n");

    return 0;
}

nand 相关说明：

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分层思想：
1. nand协议层：知道发什么，因为对于协议来说，是一个标准的协议，可以写成一个通用的文件
2. 单板相关层：对于不同的控制器和nand芯片，具体怎么发送是不一样的，所以在这里我们需要根据实际使用来进行修改，就是需要添加：不同的底层操作函数
对于驱动开发来说，也是这样。

ECC主要是为了解决NAND FLASH天生的缺陷问题：位反转。

5. 测试

5.1 烧写到NOR中启动

编译，烧写到nor，nor启动，看打印输出：
这里检测到：

NOR Flash: 2M
NAND: 256M

U-Boot 2012.04.01 (Jul 16 2015 - 09:44:17)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB
WARNING: Caches not enabled
Flash: 2 MiB
NAND:  256 MiB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   CS8900-0
SMDK2410 #

5.2 烧写到NAND中启动

利用u-boot将nor上的代码拷贝到nand上去

1. 擦出从0地址开始的512k字节大小空间
SMDK2410 # nand erase 0 80000

NAND erase: device 0 offset 0x0, size 0x80000
Erasing at 0x60000 -- 100% complete.
OK

2. 拷贝从nor的0地址开始512K字节大小的数据到nand的0地址开始处512K字节的空间
SMDK2410 # nand write 0 0 80000

NAND write: device 0 offset 0x0, size 0x80000
 524288 bytes written: OK

3. 从nand的0地址开始处的512K字节的数据拷贝到内存30000000处
SMDK2410 # nand read 30000000 0 80000

NAND read: device 0 offset 0x0, size 0x80000
 524288 bytes read: OK

4. 比较，完全相同
SMDK2410 # cmp.b 0 30000000 80000
Total of 524288 bytes were the same
SMDK2410 #

断电，从nand启动，看打印信息:

Flash: 0KB    ---->这个是nor flash的大小，为什么是0呢？？思考一下 （因为NAND启动时，0地址对应的是2440内部的RAM，所以无法访问到NOR flash）
NAND:  256 MiB

U-Boot 2012.04.01 (Jul 16 2015 - 09:44:17)

CPUID: 32440001
FCLK:      400 MHz
HCLK:      100 MHz
PCLK:       50 MHz
DRAM:  64 MiB
WARNING: Caches not enabled
Flash: 0KB
NAND:  256 MiB
*** Warning - bad CRC, using default environment

In:    serial
Out:   serial
Err:   serial
Net:   CS8900-0
SMDK2410 #

总结：

1. 分析NAND检测过程
2. 在配置文件中，增加对NAND支持的宏。
3. 根据自己的硬件NAND手册，修改NAND操作函数
4. 测试