ARM-Linux驱动--MTD驱动分析(三)

主机：Gentoo Linux 11.2 with linux kernel 3.0.6

硬件平台：FL2440（S3C2440）with linux kernel 2.6.35

本文分析MTD设备的分区管理机制

分区管理实际上是将一个MTD设备分成几个分区，将其作为单独的MTD原始设备进行管理。

1、分区的结构体描述结构体mtd_part

1. /*Ourpartitionnodestructure*/
2. //分区结构信息
3. structmtd_part{
4. structmtd_infomtd;//mtd_info数据结构，会被加入mtd_table中
5. structmtd_info*master;//该分区的主分区
6. uint64_toffset;//该分区的偏移地址
7. structlist_headlist;
8. };

2、分区链表mtd_partitions

1. /*Ourpartitionlinkedlist*/
2. //声明mtd_partitions链表
3. staticLIST_HEAD(mtd_partitions);

3、add_mtd_partitions函数

1. /*
2. *Thisfunction,givenamasterMTDobjectandapartitiontable,creates
3. *andregistersslaveMTDobjectswhichareboundtothemasteraccordingto
4. *thepartitiondefinitions.
5. *
6. *Wedontregisterthemaster,orexpectthecallertohavedoneso,
7. *forreasonsofdataintegrity.
8. */
9. //根据一个MTD主设备和分区表，创建新的主设备下的副设备并记录到分区表中
10. //这里我们不将注射被注册到分区表中，只注册副设备到到分区表中
11. intadd_mtd_partitions(structmtd_info*master,
12. conststructmtd_partition*parts,
13. intnbparts)
14. {
15. structmtd_part*slave;
16. uint64_tcur_offset=0;
17. inti;
19. printk(KERN_NOTICE"Creating%dMTDpartitionson\"%s\":\n",nbparts,master->name);
21. for(i=0;i
22. slave=add_one_partition(master,parts+i,i,cur_offset);
23. if(!slave)
24. return-ENOMEM;
25. cur_offset=slave->offset+slave->mtd.size;
26. }
28. return0;
29. }
30. EXPORT_SYMBOL(add_mtd_partitions);

而add_one_partition函数实现如下：

1. //创建一个分区
2. staticstructmtd_part*add_one_partition(structmtd_info*master,
3. conststructmtd_partition*part,intpartno,
4. uint64_tcur_offset)
5. {
6. structmtd_part*slave;
8. /*allocatethepartitionstructure*/
9. slave=kzalloc(sizeof(*slave),GFP_KERNEL);//分配内存
10. if(!slave){
11. printk(KERN_ERR"memoryallocationerrorwhilecreatingpartitionsfor\"%s\"\n",
12. master->name);
13. del_mtd_partitions(master);
14. returnNULL;
15. }
16. list_add(&slave->list,&mtd_partitions);//将原始设备表添加到分区表中
18. /*setuptheMTDobjectforthispartition*/
19. //大部分根据master相应的信息设置MTD分区slave的信息
20. slave->mtd.type=master->type;
21. slave->mtd.flags=master->flags&~part->mask_flags;
22. slave->mtd.size=part->size;
23. slave->mtd.writesize=master->writesize;
24. slave->mtd.oobsize=master->oobsize;
25. slave->mtd.oobavail=master->oobavail;
26. slave->mtd.subpage_sft=master->subpage_sft;
28. slave->mtd.name=part->name;
29. slave->mtd.owner=master->owner;
30. slave->mtd.backing_dev_info=master->backing_dev_info;
32. /*NOTE:wedontarrangeMTDsasatree;itdbeerror-prone
33. *tohavethesamedatabeintwodifferentpartitions.
34. */
35. slave->mtd.dev.parent=master->dev.parent;
37. slave->mtd.read=part_read;
38. slave->mtd.write=part_write;
40. if(master->panic_write)
41. slave->mtd.panic_write=part_panic_write;
43. if(master->point&&master->unpoint){
44. slave->mtd.point=part_point;
45. slave->mtd.unpoint=part_unpoint;
46. }
48. if(master->get_unmapped_area)
49. slave->mtd.get_unmapped_area=part_get_unmapped_area;
50. if(master->read_oob)
51. slave->mtd.read_oob=part_read_oob;
52. if(master->write_oob)
53. slave->mtd.write_oob=part_write_oob;
54. if(master->read_user_prot_reg)
55. slave->mtd.read_user_prot_reg=part_read_user_prot_reg;
56. if(master->read_fact_prot_reg)
57. slave->mtd.read_fact_prot_reg=part_read_fact_prot_reg;
58. if(master->write_user_prot_reg)
59. slave->mtd.write_user_prot_reg=part_write_user_prot_reg;
60. if(master->lock_user_prot_reg)
61. slave->mtd.lock_user_prot_reg=part_lock_user_prot_reg;
62. if(master->get_user_prot_info)
63. slave->mtd.get_user_prot_info=part_get_user_prot_info;
64. if(master->get_fact_prot_info)
65. slave->mtd.get_fact_prot_info=part_get_fact_prot_info;
66. if(master->sync)
67. slave->mtd.sync=part_sync;
68. if(!partno&&!master->dev.class&&master->suspend&&master->resume){
69. slave->mtd.suspend=part_suspend;
70. slave->mtd.resume=part_resume;
71. }
72. if(master->writev)
73. slave->mtd.writev=part_writev;
74. if(master->lock)
75. slave->mtd.lock=part_lock;
76. if(master->unlock)
77. slave->slave-