S5PV210(TQ210)学习笔记——Nand flash驱动编写

跟裸机程序一样，S5PV210的Nand flash模块跟S3C2440的Nand flash模块非常相似，如果不引入ECC，驱动程序的编写也非常简单，具体的分析及编写过程强烈推荐观看韦东山老师的视频教程，我是使用的Linux-3.8.6（Linux-3.8.3也一样）内核，驱动的API函数有些变化，不过原理是相通的，稍微看一下内核源码并参考下其他平台的相关代码就可以自己写出Nand flash驱动了，下面是Nand flash驱动的源码，没有启用ECC，当然，你也可以改成软件ECC，但是我的觉得既然软件ECC不如HWECC快，我就采用硬件ECC吧，我会在下篇文章中加入HWECC。

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>

struct s5p_nand_regs{
	unsigned long nfconf;
	unsigned long nfcont;
	unsigned long nfcmmd;
	unsigned long nfaddr;
	unsigned long nfdata;
	unsigned long nfmeccd0;
	unsigned long nfmeccd1;
	unsigned long nfseccd;
	unsigned long nfsblk;
	unsigned long nfeblk;
	unsigned long nfstat;
	unsigned long nfeccerr0;
	unsigned long nfeccerr1;
	unsigned long nfmecc0;
	unsigned long nfmecc1;
	unsigned long nfsecc;
	unsigned long nfmlcbitpt;
};

struct s5p_nand_ecc{
	unsigned long nfeccconf;
	unsigned long nfecccont;
	unsigned long nfeccstat;
	unsigned long nfeccsecstat;
	unsigned long nfeccprgecc0;
	unsigned long nfeccprgecc1;
	unsigned long nfeccprgecc2;
	unsigned long nfeccprgecc3;
	unsigned long nfeccprgecc4;
	unsigned long nfeccprgecc5;
	unsigned long nfeccprgecc6;
	unsigned long nfeccerl0;
	unsigned long nfeccerl1;
	unsigned long nfeccerl2;
	unsigned long nfeccerl3;
	unsigned long nfeccerl4;
	unsigned long nfeccerl5;
	unsigned long nfeccerl6;
	unsigned long nfeccerl7;
	unsigned long nfeccerp0;
	unsigned long nfeccerp1;
	unsigned long nfeccerp2;
	unsigned long nfeccerp3;
	unsigned long nfeccconecc0;
	unsigned long nfeccconecc1;
	unsigned long nfeccconecc2;
	unsigned long nfeccconecc3;
	unsigned long nfeccconecc4;
	unsigned long nfeccconecc5;
	unsigned long nfeccconecc6;
};

static struct nand_chip *nand_chip;
static struct mtd_info *s5p_mtd_info;
static struct s5p_nand_regs *s5p_nand_regs;
static struct s5p_nand_ecc  *s5p_nand_ecc;
static struct clk *s5p_nand_clk;

static struct mtd_partition s5p_nand_partions[] = {
	[0] = {
		.name   = "bootloader",.offset = 0,.size   = SZ_1M,},[1] = {
		.name   = "kernel",.offset = MTDPART_OFS_APPEND,.size   = 5*SZ_1M,[2] = {
		.name   = "rootfs",.size   = MTDPART_SIZ_FULL,};

static void s5p_nand_select_chip(struct mtd_info *mtd,int chipnr){
	if(chipnr == -1){
		s5p_nand_regs->nfcont |= (1<<1);
	}
	else{
		s5p_nand_regs->nfcont &= ~(1<<1);
	}
}

static void s5p_nand_cmd_ctrl(struct mtd_info *mtd,int cmd,unsigned int ctrl)
{
	if (ctrl & NAND_CLE){
		s5p_nand_regs->nfcmmd = cmd;
	}
	else{
		s5p_nand_regs->nfaddr = cmd;
	}
}

static int s5p_nand_ready(struct mtd_info *mtd){
	return (s5p_nand_regs->nfstat & 0x1);
}

static int s5p_nand_probe(struct platform_device *pdev){
	int ret = 0;
	struct resource *mem;
	//硬件部分初始化
	mem = platform_get_resource(pdev,IORESOURCE_MEM,0);
	if (!mem) {
		dev_err(&pdev->dev,"can't get I/O resource memn");
		return -ENXIO;
	}
	
	s5p_nand_regs = (struct s5p_nand_regs *)ioremap(mem->start,resource_size(mem));
	if (s5p_nand_regs == NULL) {
		dev_err(&pdev->dev,"ioremap failedn");
		ret = -EIO;
		goto err_exit;
	}

	s5p_nand_ecc = (struct s5p_nand_ecc *)ioremap(0xB0E20000,sizeof(struct s5p_nand_ecc));
	if(s5p_nand_ecc == NULL){
		dev_err(&pdev->dev,"ioremap failedn");
		ret = -EIO;
		goto err_iounmap;
	}
	
	s5p_nand_clk = clk_get(&pdev->dev,"nand");
	if(s5p_nand_clk == NULL){
		dev_dbg(&pdev->dev,"get clk failedn");
		ret = -ENODEV;
		goto err_iounmap;
	}

	clk_enable(s5p_nand_clk);
	
	s5p_nand_regs->nfconf = (3<<12)|(5<<8)|(3<<4)|(1<<1);
	s5p_nand_regs->nfcont |= 3;

	//分配驱动相关结构体
	nand_chip = (struct nand_chip *)kzalloc(sizeof(struct nand_chip),GFP_KERNEL);
	if(nand_chip == NULL){
		dev_err(&pdev->dev,"failed to allocate nand_chip structuren");
		ret = -ENOMEM;
		goto err_clk_put;
	}

	s5p_mtd_info = (struct mtd_info *)kzalloc(sizeof(struct mtd_info),GFP_KERNEL);
	if(s5p_mtd_info == NULL){
		dev_err(&pdev->dev,"failed to allocate mtd_info structuren");
		ret = -ENOMEM;
		goto err_free_chip;
	}

	//设置驱动相关结构体
	nand_chip->select_chip = s5p_nand_select_chip;
	nand_chip->cmd_ctrl    = s5p_nand_cmd_ctrl;
	nand_chip->IO_ADDR_R   = &s5p_nand_regs->nfdata;
	nand_chip->IO_ADDR_W   = &s5p_nand_regs->nfdata;
	nand_chip->dev_ready   = s5p_nand_ready;
	nand_chip->ecc.mode       = NAND_ECC_SOFT;
	
	s5p_mtd_info->priv = nand_chip;
	s5p_mtd_info->owner = THIS_MODULE;

	//扫描Nand flash 设备
	if(nand_scan(s5p_mtd_info,1)){
		dev_dbg(&pdev->dev,"nand scan errorn");
		goto err_free_info;
	}

	//添加分区信息
	ret = mtd_device_parse_register(s5p_mtd_info,NULL,s5p_nand_partions,ARRAY_SIZE(s5p_nand_partions));
	if(!ret)
		return 0;

err_free_info:
	kfree(s5p_mtd_info);
err_free_chip:
	kfree(nand_chip);
err_clk_put:
	clk_disable(s5p_nand_clk);
	clk_put(s5p_nand_clk);
err_iounmap:
	//if(s5p_nand_ecc == NULL)
	//	iounmap(s5p_nand_ecc);
	if(s5p_nand_regs == NULL)
		iounmap(s5p_nand_regs);
err_exit:
	return ret;
}

static int s5p_nand_remove(struct platform_device *pdev){
	nand_release(s5p_mtd_info);
	kfree(s5p_mtd_info);
	kfree(nand_chip);

	clk_disable(s5p_nand_clk);
	clk_put(s5p_nand_clk);

	if(s5p_nand_regs == NULL)
		iounmap(s5p_nand_regs);
	return 0;
}

static struct platform_driver s5p_nand_drv = {
	.driver = {
		.owner = THIS_MODULE,.name = "s5p-nand",.probe = s5p_nand_probe,.remove = s5p_nand_remove,};

module_platform_driver(s5p_nand_drv);
MODULE_LICENSE("GPL");

源码都在上面，具体的原理还是参考视频或者其他资料，这里就不多说了，如果有任何问题，欢迎留言讨论。

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本文作者：girlkoo