nand 设备驱动(一)架构
使用mini2440 - nand
1. nand硬件
1.1 资源
LDATD0~7数据线和地址线是复用的,都是8位
既可以传输数据(命令或者数据), 也可以发送地址信号
信号说明:
CLE: 命令锁存, 高表示cmd
ALE: 地址锁存, 高表示地址
CE :片选,低有效
R/B:状态: 低电平表示busy, 高电平表示idle,
RE:读使能,
WE:
命令集:
1.2 硬件操作
读ID命令字90, 时序如下:
2. kernel-nand驱动结构
开发板上电后有输出:
S3C24XX NAND Driver, (c) 2004 Simtec Electronics s3c2440-nand s3c2440-nand: Tacls=3, 30ns Twrph0=7 70ns, Twrph1=3 30ns NAND device: Manufacturer ID: 0xec, Chip ID: 0xda (Samsung NAND 256MiB 3,3V 8-bit) Scanning device for bad blocks
搜索“S3C24XX NAND Driver”
s3c2410.c (drivers\mtd\nand)
调用关系
s3c2410_nand_init
s3c2440_nand_driver
s3c2440_nand_probe
s3c24xx_nand_probe
s3c2410_nand_inithw
s3c2410_nand_init_chip
nand_scan
s3c2410_nand_add_partition
在s3c2410_nand_init_chip
s3c2410_nand_init_chip struct nand_chip *chip = &nmtd->chip; chip->write_buf = s3c2410_nand_write_buf; chip->read_buf = s3c2410_nand_read_buf; chip->select_chip = s3c2410_nand_select_chip; chip->cmd_ctrl = s3c2440_nand_hwcontrol; chip->dev_ready = s3c2440_nand_devready; chip->IO_ADDR_R = chip->IO_ADDR_W; nmtd->info = info; nmtd->mtd.priv = chip; nmtd->mtd.owner = THIS_MODULE;
再看nand_scan // 在文件nand_base.c
nand_scan nand_scan_ident nand_set_defaults(chip, busw); // 设置默认参数, 如果s3c2410_nand_init_chip设置了就用设置的函数 nand_get_flash_type // Get the flash and manufacturer id /* Select the device */ chip->select_chip(mtd, 0); /* Send the command for reading device ID */ chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); // 发送0x90,即读ID /* Read manufacturer and device IDs */ *maf_id = chip->read_byte(mtd); // 读厂商ID dev_id = chip->read_byte(mtd); // 读设备ID 输出“NAND device: Manufacturer ID: 0xec, Chip ID: 0xda (Samsung NAND 256MiB 3,3V 8-bit)” printk(KERN_INFO "NAND device: Manufacturer ID:" " 0x%02x, Chip ID: 0x%02x (%s %s)\n", *maf_id, dev_id, nand_manuf_ids[maf_idx].name, mtd->name); // nand_flash_ids 表示{NAND_MFR_SAMSUNG, "Samsung"}, chip->select_chip(mtd, i); chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1); // 发命令/数据
最后s3c2410_nand_add_partition
add_mtd_partitions mtd_table[i] = mtd; // mtd_table是全局数组 list_for_each(this, &mtd_notifiers) { mtd_notifiers是一个链表head, 在mtdcore.c (drivers\mtd)里面添加 register_mtd_user // mtdchar.c (drivers\mtd) 和mtd_blkdevs.c (drivers\mtd)调用,分别是字符设备和块设备
3. nand驱动编写
从上面分析看出,编写nand flash驱动主要有:
3.1 定义nand_chip *chip
3.2 设置
3.3 注册
搜索nand_scan可以看到很多例子
参考:s3c2410.c 和at91_nand.c (drivers\mtd\nand)