移植Nand flash驱动了解Linux内核Nand Flash的实现_华清远见

移植Nand flash驱动了解Linux内核Nand Flash的实现

如何通过移植Nand flash驱动，了解Linux内核Nand Flash的实现?本篇文章就来教你如何实行!在说到正题之前，先来介绍一下Nand Flash吧!

Nand-flash存储器是flash存储器的一种，其内部采用非线性宏单元模式，为固态大容量内存的实现提供了廉价有效的解决方案。Nand-flash存储器具有容量较大，改写速度快等优点，适用于大量数据的存储，因而在业界得到了越来越广泛的应用，如嵌入式产品中包括数码相机、MP3随身听记忆卡、体积小巧的U盘等。下面回到正题。

【实验目的】

Nand flash 是嵌入式系统最常用的内部存储设备，通过移植Nand flash驱动，了解Linux内核Nand Flash的实现。

说明：在本系统移植课程实验中命令行提示符“$”表示是在主机上执行，“#”表示在目标板执行。

【实验环境】

● 主机：Ubuntu 10.10 (64bit);

● 目标机：FS_S5PC100平台;

● 交叉编译工具链：arm-eabi-4.4.0(Android4.0.4自带交叉工具链);

【实验步骤】

1. 添加驱动文件

添加针对我们平台的Nand flash驱动。

● 拷贝s3c_nand.c到drivers/mtd/nand下;

● 拷贝regs-nand.h到arch/arm/mach-s5pc100/include/mach下;

cp s3c_nand.c drivers/mtd/nand

cpregs-nand.h arch/arm/mach-s5pc100/include/mach

2. 修改文件

针对平台上的nand flash设备，修改drivers/mtd/nand/nand_base.c第2975行。

for (i = 0; i< 5; i++)

3. 配置文件修改

● 修改drivers/mtd/nand/Kconfig，在if mtd_nand(216行)下面添加如下内容：config MTD_NAND_S3C

tristate "NAND Flash support for S3C SoC"

depends on (ARCH_S3C64XX || ARCH_S5P64XX || ARCH_S5PC1XX

|| ARCH_S5PC100) && MTD_NAND

help

This enables the NAND flash controller on the S3C.

No board specfic support is done by this driver, each board

must advertise a platform_device for the driver to attach.

config MTD_NAND_S3C_DEBUG

bool "S3C NAND driver debug"

depends on MTD_NAND_S3C

help

Enable debugging of the S3C NAND driver

config MTD_NAND_S3C_HWECC

bool "S3C NAND Hardware ECC"

depends on MTD_NAND_S3C

help

Enable the use of the S3C's internal ECC generator when

using NAND. Early versions of the chip have had problems with

incorrect ECC generation, and if using these, the default of

software ECC is preferable.

If you lay down a device with the hardware ECC, then you will

currently not be able to switch to software, as there is no

implementation for ECC method used by the S3C

● 修改drivers/mtd/nand/Makefile添加如下内容(19行)：obj-$(CONFIG_MTD_NAND_S3C) += s3c_nand.o

4. 平台代码修改

修改arch/arm/mach-s5pc100/mach-smdkc100.c添加如下内容：

● 添加头文件

1 #if defined (CONFIG_MTD_NAND_S3C)

2 #include

3 #include

4 #include

5 #endif

● 添加平台设备

01 #if defined(CONFIG_MTD_NAND_S3C)

02 /* Nand Flash Support */

03 static structmtd_partition s5pc100_nand_part[] = {

04 [0] = {

05 .name = "bootloader",

06 .size = SZ_1M,

07 .offset = 0,

08 },

09 [1] = {

10 .name = "kernel",

11 .offset = MTDPART_OFS_APPEND,

12 .size = SZ_1M*3,

13 },

14 [2] = {

15 .name = "rootfs",

16 .offset = MTDPART_OFS_APPEND,

17 .size = MTDPART_SIZ_FULL,

18 },

19 };

20

21 struct s3c_nand_mtd_info s5pc100_nand_mtd_part_info = {

22 .chip_nr = 1,

23 .mtd_part_nr = ARRAY_SIZE(s5pc100_nand_part),

24 .partition = s5pc100_nand_part,

25 };

26

27 static struct resource s5pc100_nand_resource[] = {

28 [0] = {

29 .start = 0xE7200000,

30 .end = 0xE7200000 + SZ_1M,

31 .flags = IORESOURCE_MEM,

32 }

33 };

34

35 structplatform_device s5pc100_device_nand = {

36 .name = "s5pc100-nand",

37 .id = -1,

38 .num_resources = ARRAY_SIZE(s5pc100_nand_resource),

39 .resource = s5pc100_nand_resource,

40 .dev = {

41 .platform_data = &s5pc100_nand_mtd_part_info,

42 }

43 };

44 #endif

● 添加平台设备列表

在smdkc100_device[]结构体数组中添加如下内容：

1 #if defined(CONFIG_MTD_NAND_S3C)

2 &s5pc100_device_nand,

3 #endif

5. 相关头文件修改

修改arch/arm/plat-samsung/include/plat/nand.h添加如下内容：

1 #if defined(CONFIG_MTD_NAND_S3C)

2 struct s3c_nand_mtd_info {

3 uintchip_nr;

4 uintmtd_part_nr;

5 structmtd_partition *partition;

6 };

7 #endif

6. 配置内核

$ make menuconfig

Device Drivers --->

<*> Memory Technology Device (MTD) support --->

<*> Caching block device access to MTD devices

<*> NAND Device Support --->

<*> NAND Flash support for S3C SoC

[*] S3C NAND Hardware ECC

-*- Enable the block layer --->

Partition Types --->

[*] Advanced partition selection

[*] PC BIOS (MSDOS partition tables) support

[*] BSD disklabel (FreeBSD partition tables) support 7. 编译内核

编译内核并拷贝到tftpboot下。

$ make zImage

$ cp arch/arm/boot/zImage /tftpboot

8. 测试

启动目标板，在目标板上完成如下操作：

# cat /proc/mtd

可以看到之前内核对Nand Flash的分区表。

dev: size erasesize name

mtd0: 00100000 00020000 "bootloader"

mtd1: 00300000 00020000 "kernel"

mtd2: 0fc00000 00020000 "rootfs"

如何移植Nand flash驱动了解Linux内核Nand Flash的实现，现在你知道怎么操作了吗?linux的世界非常奇妙，更多学习内容可以在华清远见官网查看，华清远见提供免费的学习参考资料，供大家学习。