linux 裝置驅動 nand驅動框架
阿新 • • 發佈:2018-11-08
nand 裝置驅動(一)架構
使用mini2440 - nand
1. nand硬體
1.1 資源
LDATD0~7資料線和地址線是複用的,都是8位
既可以傳輸資料(命令或者資料), 也可以傳送地址訊號
訊號說明:
CLE: 命令鎖存, 高表示cmd
ALE: 地址鎖存, 高表示地址
CE :片選,低有效
R/B:狀態: 低電平表示busy, 高電平表示idle,
RE:讀使能,
WE:
命令集:
1.2 硬體操作
讀ID命令字90, 時序如下:
2. kernel-nand驅動結構
開發板上電後有輸出:
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
搜尋“S3C24XX NAND Driver”
s3c2410.c (drivers\mtd\nand)
呼叫關係 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 // 在檔案nand_base.c
nand_scan nand_scan_ident nand_set_defaults(chip, busw); // 設定預設引數, 如果s3c2410_nand_init_chip設定了就用設定的函式 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); // 傳送0x90,即讀ID /* Read manufacturer and device IDs */ *maf_id = chip->read_byte(mtd); // 讀廠商ID dev_id = chip->read_byte(mtd); // 讀裝置ID 輸出“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); // 發命令/資料
最後s3c2410_nand_add_partition
add_mtd_partitions mtd_table[i] = mtd; // mtd_table是全域性陣列 list_for_each(this, &mtd_notifiers) { mtd_notifiers是一個連結串列head, 在mtdcore.c (drivers\mtd)裡面新增 register_mtd_user // mtdchar.c (drivers\mtd) 和mtd_blkdevs.c (drivers\mtd)呼叫,分別是字元裝置和塊裝置
3. nand驅動編寫
從上面分析看出,編寫nand flash驅動主要有:
3.1 定義nand_chip *chip
3.2 設定
3.3 註冊
搜尋nand_scan可以看到很多例子
參考:s3c2410.c 和at91_nand.c (drivers\mtd\nand)