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分类: LINUX

2008-03-22 12:53:05




    开发板上只有Nor Flash,所以为了实现层次文件系统,需要为Linux2.6.20增加Nor Flash MTD驱动支持。其实工作量并不大,因为已经有现成的程序可供参考。
 
    MTD的驱动程序都集中在drivers/mtd里面。我们需要做的,仅仅是在drivers/mtd/maps下增加自己的分区表。因为有参考的代码,所以比较容易。
 
(1)构建配置选项
 
    首先,根据edb7312.c构建自己的mtd分区表驱动。
 

$cd drivers/mtd/maps/
$cp edb7312.c at91rm9200.c

 
    然后,修改Kconfig,增加自己的配置选项。
 

//拷贝过EDB7312稍作修改即可
config MTD_AT91RM9200
        tristate "CFI Flash device mapped on AT91RM9200"
        depends on ARM && MTD_CFI
        help
          This enables access to the CFI Flash on the ATMEL AT91RM9200DK board.
          If you have such a board, say 'Y' here.

 
    最后,修改Makefile,增加编译项目。
 

obj-$(CONFIG_MTD_EDB7312) += edb7312.o
obj-$(CONFIG_MTD_AT91RM9200) += at91rm9200.o

 
    这样,自己建立的MTD分区表驱动就可以编译进内核了。
 
(2)修改分区表信息
 
    因为第一步的工作中,at91rm9200.c实际上还是edb7312.c的内容,所以需要根据自己的开发板nor flash的配置做一下修改。
 

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/map.h>

#ifdef CONFIG_MTD_PARTITIONS
#include <linux/mtd/partitions.h>
#endif

#define WINDOW_ADDR 0x10000000 /* physical properties of flash */
#define WINDOW_SIZE 0x00800000 /* intel 28F640J3A 8MB */
#define BUSWIDTH 2 /* data bus width 16bits */
/* can be "cfi_probe", "jedec_probe", "map_rom", NULL }; */
#define PROBETYPES { "cfi_probe", NULL }

#define MSG_PREFIX "AT91RM9200-NOR:" /* prefix for our printk()'s */
#define MTDID "at91rm9200-%d" /* for mtdparts= partitioning */

static struct mtd_info *mymtd;

struct map_info at91rm9200nor_map = {
        .name = "NOR flash on AT91RM9200DK",
        .size = WINDOW_SIZE,
        .bankwidth = BUSWIDTH,
        .phys = WINDOW_ADDR,
};

#ifdef CONFIG_MTD_PARTITIONS

/*
 * MTD partitioning stuff
 */

static struct mtd_partition at91rm9200nor_partitions[5] =
{
        {
                
// U-boot 128KB
                .name = "U-boot",
                .size = 0x20000,
                .offset = 0
        },
        {
                
// uImage 2MB
                .name = "Kernel",
                .size = 0x200000,
                .offset = 0x20000
        },
        {
                
// RootFS 3MB
                .name = "RootFS",
                .size = 0x300000,
                .offset = 0x220000
        },
        {
                
// UserFS
                .name = "Jffs2",
                .size = 0x2C0000,
                .offset = 0x520000
        },
        {
                
// Parameters
                .name = "Parameters",
                .size = 0x20000,
                .offset = 0x7E0000
        },
};

static const char *probes[] = { NULL };

#endif

static int mtd_parts_nb = 0;
static struct mtd_partition *mtd_parts = 0;

int __init init_at91rm9200nor(void)
{
        static const char *rom_probe_types[] = PROBETYPES;
        const char **type;
        const char *part_type = 0;

        printk(KERN_NOTICE MSG_PREFIX "0x%08x at 0x%08x\n",
               WINDOW_SIZE, WINDOW_ADDR);
        at91rm9200nor_map.virt = ioremap(WINDOW_ADDR, WINDOW_SIZE);

        if (!at91rm9200nor_map.virt) {
                printk(MSG_PREFIX "failed to ioremap\n");
                return -EIO;
        }

        simple_map_init(&at91rm9200nor_map);

        mymtd = 0;
        type = rom_probe_types;
        for(; !mymtd && *type; type++) {
                mymtd = do_map_probe(*type, &at91rm9200nor_map);
        }
        if (mymtd) {
                mymtd->owner = THIS_MODULE;

#ifdef CONFIG_MTD_PARTITIONS
                mtd_parts_nb = parse_mtd_partitions(mymtd, probes, &mtd_parts, 0);
                if (mtd_parts_nb > 0)
                  part_type = "detected";

                if (mtd_parts_nb == 0)
                {
                        mtd_parts = at91rm9200nor_partitions;
                        mtd_parts_nb = ARRAY_SIZE(at91rm9200nor_partitions);
                        part_type = "static";
                }
#endif
                add_mtd_device(mymtd);
                if (mtd_parts_nb == 0)
                  printk(KERN_NOTICE MSG_PREFIX "no partition info available\n");
                else
                {
                        printk(KERN_NOTICE MSG_PREFIX
                               "using %s partition definition\n", part_type);
                        add_mtd_partitions(mymtd, mtd_parts, mtd_parts_nb);
                }
                return 0;
        }

        iounmap((void *)at91rm9200nor_map.virt);
        return -ENXIO;
}

static void __exit cleanup_at91rm9200nor(void)
{
        if (mymtd) {
                del_mtd_device(mymtd);
                map_destroy(mymtd);
        }
        if (at91rm9200nor_map.virt) {
                iounmap((void *)at91rm9200nor_map.virt);
                at91rm9200nor_map.virt = 0;
        }
}

module_init(init_at91rm9200nor);
module_exit(cleanup_at91rm9200nor);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Marius Groeger ");
MODULE_DESCRIPTION("Generic configurable MTD map driver");

 
(3)配置内核
 
    增加MTD,和相应的文件系统的支持。
 
    Devices Drivers --->
            Memory Technology Devices (MTD) --->
                 <*> Memory Technology Device(MTD) support
                 <*> MTD partitioning support
                 <*> Direct char device access to MTD devices
                 <*> Caching block device access to MTD devices
                 RAM/ROM/Flash chip drivers --->
                     <*> Detect flash chips by Common Flash Interface(CFI) probe
                     <*> Support for Intel/Sharp flash chips
                 Mapping drivers for chip access --->
                     <*> CFI Flash device mapped on AT91RM9200
    File Systems --->
           Miscellaneous filesystems --->
                这里选择cramfs或者Jffs2的支持。
 
(4)编译,然后加载
 
    make Image编译,然后制作成uImage。
 

TOPDIR=$($(which pwd))
TMP=$TOPDIR/linux.bin
TARGET=$TOPDIR/uImage

arm-linux-objcopy -O binary -S vmlinux $TMP && gzip -v9 $TMP && \
mkimage -n 'RAM disk' -A arm -O linux -T kernel -C gzip \
        -a 0x20008000 -e 0x20008000 -d $TMP.gz $TARGET && \
cp $TARGET /mnt/hgfs/common && \
rm -f $TMP*

 
    这是JFFS2作为根文件系统的信息:
 

AT91RM9200-NOR:0x00800000 at 0x10000000
NOR flash on AT91RM9200DK: Found 1 x16 devices at 0x0 in 16-bit bank
 Intel/Sharp Extended Query Table at 0x0031
Using buffer write method
cfi_cmdset_0001: Erase suspend on write enabled
AT91RM9200-NOR:using static partition definition
Creating 5 MTD partitions on "NOR flash on AT91RM9200DK":
0x00000000-0x00020000 : "U-boot"
0x00020000-0x00220000 : "Kernel"
0x00220000-0x00520000 : "RootFS"
0x00520000-0x007e0000 : "Jffs2"
0x007e0000-0x00800000 : "Parameters"

 

JFFS2 notice: (1) jffs2_build_xattr_subsystem: complete building xattr subsystem, 0 of xdatum (0 unchecked, 0 orphan) and 0 of xref (0 dead, 0 orphan) found.
VFS: Mounted root (jffs2 filesystem).
Freeing init memory: 100K
init started: BusyBox v1.9.1 (2008-03-15 15:28:44 CST)
starting pid 710, tty '': '/etc/init.d/rcS'

 
    可以看到MTD分区信息。进入shell界面,然后查看/proc/mtd,如下:
 

[root@lqm ~]#cat /proc/mtd
dev: size erasesize name
mtd0: 00800000 00020000 "NOR flash on AT91RM9200DK"
mtd1: 00020000 00020000 "U-boot"
mtd2: 00200000 00020000 "Kernel"
mtd3: 00300000 00020000 "RootFS"
mtd4: 002c0000 00020000 "Jffs2"
mtd5: 00020000 00020000 "Parameters"

 
    可以看到加载是正确的。
 

 
附:MAC地址全零的解决

/*
 * Set the ethernet MAC address in dev->dev_addr
 */

static void __init get_mac_address(struct net_device *dev)
{
        #if 0
        /* Check Specific-Address 1 */
        if (unpack_mac_address(dev, at91_emac_read(AT91_EMAC_SA1H), at91_emac_read(AT91_EMAC_SA1L)))
                return;
        /* Check Specific-Address 2 */
        if (unpack_mac_address(dev, at91_emac_read(AT91_EMAC_SA2H), at91_emac_read(AT91_EMAC_SA2L)))
                return;
        /* Check Specific-Address 3 */
        if (unpack_mac_address(dev, at91_emac_read(AT91_EMAC_SA3H), at91_emac_read(AT91_EMAC_SA3L)))
                return;
        /* Check Specific-Address 4 */
        if (unpack_mac_address(dev, at91_emac_read(AT91_EMAC_SA4H), at91_emac_read(AT91_EMAC_SA4L)))
                return;
        #endif

        static char def_mac[] = {0x36, 0xB9, 0x04, 0x00, 0x24, 0x80};
        memcpy(dev->dev_addr, def_mac, 6);
        printk(KERN_ERR "at91_ether: Your bootloader did not configure a MAC address.\n");
}

 
    位置是drivers/net/arm/at91_ether.c。这样就获得临时解决了。
阅读(2049) | 评论(3) | 转发(1) |
给主人留下些什么吧!~~

chinaunix网友2010-12-08 15:19:24

根文件系统一直挂载不上,不知道哪里设置出了问题

chinaunix网友2008-04-08 12:06:57

小弟也是刚刚开始看mtd,具体的流程还不是很清楚,问到什么外行人的问题,还请楼主指点一下。不知道有没有什么相关资料给我学习一下。 邮箱:zonian84@gmail.com Thanks!!!!!!

chinaunix网友2008-04-08 12:03:04

问下楼主关于一点mtd的问题。 1. 假如我的uboot烧进板子,mtd_partition中关于uboot分区这块是填我的Uboot放置的地址,是吗? 2. 貌似你在建立好mtd后,并没有把自己创建的jffs2文件系统放到生成的mtd设备中去。 3. 你的系统中有RootFs,因此你的jffs2的文件系统是mount到RootFs上去的,是不?是的话,为什么不直接把自己的Jffs2文件系统作为根目录使用。 4. 在target上启动系统之前,是把相应的东西(uboot.bin、vmlinux、rootfs)放到相应地址就行了,还是要放进时flash后再使用dd把它们放到相应的mtd设备中去

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