11-S3C6410 nand_chip初始化与NAND探测
19.5.2 S3C6410 nand_chip初始化与NAND探测
S3C6410的NAND驱动以platform驱动的形式存在，在执行probe()时，初始化nand_chip实例并运行nand_scan()扫描NAND设备，最后调用add_mtd_partitions()添加板文件platform中定义的分区表。nand_chip是NAND Flash驱动的核心数据结构，这个结构体中的成员直接对应着NAND Flash的底层操作，针对具体的NAND控制器情况，本驱动中初始化了IO_ADDR_R、IO_ADDR_W、cmd_ctrl()、dev_ready()、scan_bbt()以及ECC相关的信息。代码清单19.14所示为S3C6410外围NAND Flash驱动的nand_chip初始化与注册过程。
代码清单19.14 S3C6410 nand_chip初始化与注册
1 static int s3c_nand_probe(struct platform_device *pdev, enum s3c_cpu_type cpu_type)
2 {
3 ...
4 for (i = 0; i < plat_info→chip_nr; i++) {
5 nand→IO_ADDR_R = (char *)(s3c_nand.regs + S3C_NFDATA);
6 nand→IO_ADDR_W = (char *)(s3c_nand.regs + S3C_NFDATA);
7 nand→cmd_ctrl = s3c_nand_hwcontrol;
8 nand→dev_ready = s3c_nand_device_ready;
9 nand→scan_bbt = s3c_nand_scan_bbt;
10 nand→options = 0;
11
12 #if defined(CONFIG_MTD_NAND_S3C_CACHEDPROG)
13 nand→options |= NAND_CACHEPRG;
14 #endif
15
16 #if defined(CONFIG_MTD_NAND_S3C_HWECC)
17 nand→ecc.mode = NAND_ECC_HW;
18 nand→ecc.hwctl = s3c_nand_enable_hwecc;
19 nand→ecc.calculate = s3c_nand_calculate_ecc;
20 nand→ecc.correct = s3c_nand_correct_data;
21
22 s3c_nand_hwcontrol(0, NAND_CMD_READID, NAND_NCE|NAND_CLE| NAND_CTRL_CHANGE);
23 s3c_nand_hwcontrol(0, 0x00, NAND_CTRL_CHANGE | NAND_NCE | NAND_ALE);
24 s3c_nand_hwcontrol(0, 0x00, NAND_NCE | NAND_ALE);
25 s3c_nand_hwcontrol(0, NAND_CMD_NONE, NAND_NCE | NAND_CTRL_CHANGE);
26 s3c_nand_device_ready(0);
27
28 tmp = readb(nand→IO_ADDR_R); / 制造商ID /
29 tmp = readb(nand→IO_ADDR_R); / 设备ID /
30 devID = tmp;
31
32 for (j = 0; nand_flash_ids[j].name != NULL; j++) {
33 if (tmp == nand_flash_ids[j].id) {
34 type = &nand_flash_ids[j];
35 break;
36 }
37 }
38
39 ...
40 nand→cellinfo = readb(nand→IO_ADDR_R); / 第3个字节 /
41 tmp = readb(nand→IO_ADDR_R); / 第4个字节 /
42
43 if (!type→pagesize) {
44 if (((nand→cellinfo >> 2) & 0x3) == 0) {
45 nand_type = S3C_NAND_TYPE_SLC;
46 nand→ecc.size = 512;
47 nand→ecc.bytes = 4;
48 if (devID == 0xd5) {
49 / Page size is 4Kbytes /
50 nand→ecc.read_page = s3c_nand_read_page_8bit;
51 ...
52 } else {
53 if ((1024 << (tmp & 3)) == 4096) / For 4KB Page 8_bit ECC /
54 {
55 / Page size is 4Kbytes /
56 nand→ecc.read_page = s3c_nand_read_page_8bit;
57 ...
58 } else {
59 ...
60 }
61 }
62 } else {
63 nand_type = S3C_NAND_TYPE_MLC;
64 nand→options |= NAND_NO_SUBPAGE_WRITE; / NOP = 1 if MLC /
65 if (devID == 0xd5) {
66 / Page size is 4Kbytes /
67 nand→ecc.read_page = s3c_nand_read_page_8bit;
68 nand→ecc.write_page = s3c_nand_write_page_8bit;
69 ...
70 } else {
71 if ((1024 << (tmp & 3)) == 4096) {
72 / Page size is 4Kbytes /
73 nand→ecc.read_page = s3c_nand_read_page_8bit;
74 nand→ecc.write_page = s3c_nand_write_page_8bit;
75 nand→ecc.read_oob = s3c_nand_read_oob_8bit;
76 ...
77 } else {
78 nand→ecc.read_page = s3c_nand_read_page_4bit;
79 ...
80 }
81 }
82 }
83 ...
84
85 printk("S3C NAND Driver is using hardware ECC.\n");
86 #else
87 nand→ecc.mode = NAND_ECC_SOFT;
88 printk("S3C NAND Driver is using software ECC.\n");
89 #endif
90 if (nand_scan(s3c_mtd, 1)) {
91 ret = -ENXIO;
92 goto exit_error;
93 }
94
95 / 注册分区信息 /
96 add_mtd_partitions(s3c_mtd, partition_info, plat_info→mtd_part_nr);
97 }
98
99 pr_debug("initialized ok\n");
100 return 0;
101 ...
102 }
drivers/mtd/nand/s3c_nand.c是一个platform驱动，我们在LDD6410的BSP中只需要添加相关的针对NAND的platform设备和分区信息即可。