ARM-Linux驅動--MTD驅動分析(三)

主機：Gentoo Linux 11.2 with linux kernel 3.0.6

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

本文引用地址：http://www.104case.com/article/201611/319014.htm

本文分析MTD設備的分區管理機制

分區管理實際上是將一個MTD設備分成幾個分區，將其作為單獨的MTD原始設備進行管理。

1、分區的結構體描述結構體mtd_part

1. /*Ourpartitionnodestructure*/
2. //分區結構信息
3. structmtd_part{
4. structmtd_infomtd;//mtd_info數據結構，會被加入mtd_table中
5. structmtd_info*master;//該分區的主分區
6. uint64_toffset;//該分區的偏移地址
7. structlist_headlist;
8. };

2、分區鏈表mtd_partitions

1. /*Ourpartitionlinkedlist*/
2. //聲明mtd_partitions鏈表
3. staticLIST_HEAD(mtd_partitions);

3、add_mtd_partitions函數

1. /*
2. *Thisfunction,givenamasterMTDobjectandapartitiontable,creates
3. *andregistersslaveMTDobjectswhichareboundtothemasteraccordingto
4. *thepartitiondefinitions.
5. *
6. *Wedontregisterthemaster,orexpectthecallertohavedoneso,
7. *forreasonsofdataintegrity.
8. */
9. //根據一個MTD主設備和分區表，創建新的主設備下的副設備并記錄到分區表中
10. //這里我們不將注射被注冊到分區表中，只注冊副設備到到分區表中
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函數實現如下：

1. //創建一個分區
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);//分配內存
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);//將原始設備表添加到分區表中
18. /*setuptheMTDobjectforthispartition*/
19. //大部分根據master相應的信息設置MTD分區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->mtd.unlock=part_unlock;
78. if(master->block_isbad)
79. slave->mtd.block_isbad=part_block_isbad;
80. if(master->block_markbad)
81. slave->mtd.block_markbad=part_block_markbad;
82. slave->mtd.erase=part_erase;
83. slave->master=master;
84. slave->offset=part->offset;
86. if(slave->offset==MTDPART_OFS_APPEND)
87. slave->offset=cur_offset;
88. if(slave->offset==MTDPART_OFS_NXTBLK){
89. slave->offset=cur_offset;
90. if(mtd_mod_by_eb(cur_offset,master)!=0){
91. /*Rounduptonexterasesize*/
92. slave->offset=(mtd_div_by_eb(cur_offset,master)+1)*master->erasesize;
93. printk(KERN_NOTICE"Movingpartition%d:"
94. "0x%012llx->0x%012llxn",partno,
95. (unsignedlonglong)cur_offset,(unsignedlonglong)slave->offset);
96. }
97. }
98. if(slave->mtd.size==MTDPART_SIZ_FULL)
99. slave->mtd.size=master->size-slave->offset;
101. printk(KERN_NOTICE"0x%012llx-0x%012llx:"%s"n",(unsignedlonglong)slave->offset,
102. (unsignedlonglong)(slave->offset+slave->mtd.size),slave->mtd.name);
104. /*letsdosomesanitychecks*/
105. if(slave->offset>=master->size){
106. /*letsregisteritanywaytopreserveordering*/
107. slave->offset=0;
108. slave->mtd.size=0;
109. printk(KERN_ERR"mtd:partition"%s"isoutofreach--disabledn",
110. part->name);
111. gotoout_register;
112. }
113. if(slave->offset+slave->mtd.size>master->size){
114. slave->mtd.size=master->size-slave->offset;
115. printk(KERN_WARNING"mtd:partition"%s"extendsbeyondtheendofdevice"%s"--sizetruncatedto%#llxn",
116. part->name,master->name,(unsignedlonglong)slave->mtd.size);
117. }
118. if(master->numeraseregions>1){
119. /*Dealwithvariableerasesizestuff*/
120. inti,max=master->numeraseregions;
121. u64end=slave->offset+slave->mtd.size;
122. structmtd_erase_region_info*regions=master->eraseregions;
124. /*Findthefirsteraseregionswhichispartofthis
125. *partition.*/
126. for(i=0;ioffset;i++)
127. ;
128. /*Theloopsearchedfortheregion_behind_thefirstone*/
129. if(i>0)
130. i--;
132. /*Pickbiggesterasesize*/
133. for(;i
134. if(slave->mtd.erasesize
135. slave->mtd.erasesize=regions[i].erasesize;
136. }
137. }
138. BUG_ON(slave->mtd.erasesize==0);
139. }else{
140. /*Singleerasesize*/
141. slave->mtd.erasesize=master->erasesize;
142. }
144. if((slave->mtd.flags&MTD_WRITEABLE)&&
145. mtd_mod_by_eb(slave->offset,&slave->mtd)){
146. /*Doesntstartonaboundaryofmajorerasesize*/
147. /*FIXME:Letitbewritableifitisonaboundaryof
148. *_minor_erasesizethough*/
149. slave->mtd.flags&=~MTD_WRITEABLE;
150. printk(KERN_WARNING"mtd:partition"%s"doesntstartonaneraseblockboundary--forceread-onlyn",
151. part->name);
152. }
153. if((slave->mtd.flags&MTD_WRITEABLE)&&
154. mtd_mod_by_eb(slave->mtd.size,&slave->mtd)){
155. slave->mtd.flags&=~MTD_WRITEABLE;
156. printk(KERN_WARNING"mtd:partition"%s"doesntendonaneraseblock--forceread-onlyn",
157. part->name);
158. }
160. slave->mtd.ecclayout=master->ecclayout;
161. if(master->block_isbad){
162. uint64_toffs=0;
164. while(offsmtd.size){
165. if(master->block_isbad(master,
166. offs+slave->offset))
167. slave->mtd.ecc_stats.badblocks++;
168. offs+=slave->mtd.erasesize;
169. }
170. }
172. out_register:
173. /*registerourpartition*/
174. //最后調用add_mtd_device根據該設備的mtd_info信息添加設備鏈表，將其作為一個獨立的MTD原始設備
175. add_mtd_device(&slave->mtd);
177. returnslave;
178. }

4、del_mtd_partition函數

1. /*
2. *ThisfunctionunregistersanddestroyallslaveMTDobjectswhichare
3. *attachedtothegivenmasterMTDobject.
4. */
5. //將一個主設備下的所有副設備刪除
6. intdel_mtd_partitions(structmtd_info*master)
7. {
8. structmtd_part*slave,*next;
10. list_for_each_entry_safe(slave,next,&mtd_partitions,list)//遍歷mtd_partitions鏈表，查找到指定的主設備
11. if(slave->master==master){
12. list_del(&slave->list);//將主設備下的附屬設備刪除
13. del_mtd_device(&slave->mtd);//調用del_mtd_device函數將每個設備從MTD原始設備表中刪除
14. kfree(slave);//釋放內存
15. }
17. return0;
18. }
19. EXPORT_SYMBOL(del_mtd_partitions);

5、其他的分區管理函數

1. /*
2. *MTDmethodswhichsimplytranslatetheeffectiveaddressandpassthrough
3. *tothe_real_device.
4. */
5. //讀取某個分區的指定數據
6. staticintpart_read(structmtd_info*mtd,loff_tfrom,size_tlen,
7. size_t*retlen,u_char*buf)
8. {
9. structmtd_part*part=PART(mtd);
10. structmtd_ecc_statsstats;
11. intres;
13. stats=part->master->ecc_stats;
15. if(from>=mtd->size)
16. len=0;
17. elseif(from+len>mtd->size)
18. len=mtd->size-from;
19. res=part->master->read(part->master,from+part->offset,
20. len,retlen,buf);
21. if(unlikely(res)){
22. if(res==-EUCLEAN)
23. mtd->ecc_stats.corrected+=part->master->ecc_stats.corrected-stats.corrected;
24. if(res==-EBADMSG)
25. mtd->ecc_stats.failed+=part->master->ecc_stats.failed-stats.failed;
26. }
27. returnres;
28. }
30. staticintpart_point(structmtd_info*mtd,loff_tfrom,size_tlen,
31. size_t*retlen,void**virt,resource_size_t*phys)
32. {
33. structmtd_part*part=PART(mtd);
34. if(from>=mtd->size)
35. len=0;
36. elseif(from+len>mtd->size)
37. len=mtd->size-from;
38. returnpart->master->point(part->master,from+part->offset,
39. len,retlen,virt,phys);
40. }
42. staticvoidpart_unpoint(structmtd_info*mtd,loff_tfrom,size_tlen)
43. {
44. structmtd_part*part=PART(mtd);
46. part->master->unpoint(part->master,from+part->offset,len);
47. }
48. //獲取空閑的內存驅動
49. staticunsignedlongpart_get_unmapped_area(structmtd_info*mtd,
50. unsignedlonglen,
51. unsignedlongoffset,
52. unsignedlongflags)
53. {
54. structmtd_part*part=PART(mtd);
56. offset+=part->offset;
57. returnpart->master->get_unmapped_area(part->master,len,offset,
58. flags);
59. }
61. staticintpart_read_oob(structmtd_info*mtd,loff_tfrom,
62. structmtd_oob_ops*ops)
63. {
64. structmtd_part*part=PART(mtd);
65. intres;
67. if(from>=mtd->size)
68. return-EINVAL;
69. if(ops->datbuf&&from+ops->len>mtd->size)
70. return-EINVAL;
71. res=part->master->read_oob(part->master,from+part->offset,ops);
73. if(unlikely(res)){
74. if(res==-EUCLEAN)
75. mtd->ecc_stats.corrected++;
76. if(res==-EBADMSG)
77. mtd->ecc_stats.failed++;
78. }
79. returnres;
80. }
82. staticintpart_read_user_prot_reg(structmtd_info*mtd,loff_tfrom,
83. size_tlen,size_t*retlen,u_char*buf)
84. {
85. structmtd_part*part=PART(mtd);
86. returnpart->master->read_user_prot_reg(part->master,from,
87. len,retlen,buf);
88. }
90. staticintpart_get_user_prot_info(structmtd_info*mtd,
91. structotp_info*buf,size_tlen)
92. {
93. structmtd_part*part=PART(mtd);
94. returnpart->master->get_user_prot_info(part->master,buf,len);
95. }
97. staticintpart_read_fact_prot_reg(structmtd_info*mtd,loff_tfrom,
98. size_tlen,size_t*retlen,u_char*buf)
99. {
100. structmtd_part*part=PART(mtd);
101. returnpart->master->read_fact_prot_reg(part->master,from,
102. len,retlen,buf);
103. }
105. staticintpart_get_fact_prot_info(structmtd_info*mtd,structotp_info*buf,
106. size_tlen)
107. {
108. structmtd_part*part=PART(mtd);
109. returnpart->master->get_fact_prot_info(part->master,buf,len);
110. }
111. //分區寫函數
112. staticintpart_write(structmtd_info*mtd,loff_tto,size_tlen,
113. size_t*retlen,constu_char*buf)
114. {
115. structmtd_part*part=PART(mtd);
116. if(!(mtd->flags&MTD_WRITEABLE))
117. return-EROFS;
118. if(to>=mtd->size)
119. len=0;
120. elseif(to+len>mtd->size)
121. len=mtd->size-to;
122. returnpart->master->write(part->master,to+part->offset,
123. len,retlen,buf);
124. }
126. staticintpart_panic_write(structmtd_info*mtd,loff_tto,size_tlen,
127. size_t*retlen,constu_char*buf)
128. {
129. structmtd_part*part=PART(mtd);
130. if(!(mtd->flags&MTD_WRITEABLE))
131. return-EROFS;
132. if(to>=mtd->size)
133. len=0;
134. elseif(to+len>mtd->size)
135. len=mtd->size-to;
136. returnpart->master->panic_write(part->master,to+part->offset,
137. len,retlen,buf);
138. }
140. staticintpart_write_oob(structmtd_info*mtd,loff_tto,
141. structmtd_oob_ops*ops)
142. {
143. structmtd_part*part=PART(mtd);
145. if(!(mtd->flags&MTD_WRITEABLE))
146. return-EROFS;
148. if(to>=mtd->size)
149. return-EINVAL;
150. if(ops->datbuf&&to+ops->len>mtd->size)
151. return-EINVAL;
152. returnpart->master->write_oob(part->master,to+part->offset,ops);
153. }
155. staticintpart_write_user_prot_reg(structmtd_info*mtd,loff_tfrom,
156. size_tlen,size_t*retlen,u_char*buf)
157. {
158. structmtd_part*part=PART(mtd);
159. returnpart->master->write_user_prot_reg(part->master,from,
160. len,retlen,buf);
161. }
163. staticintpart_lock_user_prot_reg(structmtd_info*mtd,loff_tfrom,
164. size_tlen)
165. {
166. structmtd_part*part=PART(mtd);
167. returnpart->master->lock_user_prot_reg(part->master,from,len);
168. }
170. staticintpart_writev(structmtd_info*mtd,conststructkvec*vecs,
171. unsignedlongcount,loff_tto,size_t*retlen)
172. {
173. structmtd_part*part=PART(mtd);
174. if(!(mtd->flags&MTD_WRITEABLE))
175. return-EROFS;
176. returnpart->master->writev(part->master,vecs,count,
177. to+part->offset,retlen);
178. }
180. staticintpart_erase(structmtd_info*mtd,structerase_info*instr)
181. {
182. structmtd_part*part=PART(mtd);
183. intret;
184. if(!(mtd->flags&MTD_WRITEABLE))
185. return-EROFS;
186. if(instr->addr>=mtd->size)
187. return-EINVAL;
188. instr->addr+=part->offset;
189. ret=part->master->erase(part->master,instr);
190. if(ret){
191. if(instr->fail_addr!=MTD_FAIL_ADDR_UNKNOWN)
192. instr->fail_addr-=part->offset;
193. instr->addr-=part->offset;
194. }
195. returnret;
196. }
198. voidmtd_erase_callback(structerase_info*instr)
199. {
200. if(instr->mtd->erase==part_erase){
201. structmtd_part*part=PART(instr->mtd);
203. if(instr->fail_addr!=MTD_FAIL_ADDR_UNKNOWN)
204. instr->fail_addr-=part->offset;
205. instr->addr-=part->offset;
206. }
207. if(instr->callback)
208. instr->callback(instr);
209. }
210. EXPORT_SYMBOL_GPL(mtd_erase_callback);
212. staticintpart_lock(structmtd_info*mtd,loff_tofs,uint64_tlen)
213. {
214. structmtd_part*part=PART(mtd);
215. if((len+ofs)>mtd->size)
216. return-EINVAL;
217. returnpart->master->lock(part->master,ofs+part->offset,len);
218. }
220. staticintpart_unlock(structmtd_info*mtd,loff_tofs,uint64_tlen)
221. {
222. structmtd_part*part=PART(mtd);
223. if((len+ofs)>mtd->size)
224. return-EINVAL;
225. returnpart->master->unlock(part->master,ofs+part->offset,len);
226. }
227. //分區同步函數
228. staticvoidpart_sync(structmtd_info*mtd)
229. {
230. structmtd_part*part=PART(mtd);
231. part->master->sync(part->master);
232. }
233. //支持電源管理的功能函數
234. staticintpart_suspend(structmtd_info*mtd)
235. {
236. structmtd_part*part=PART(mtd);
237. returnpart->master->suspend(part->master);
238. }
240. staticvoidpart_resume(structmtd_info*mtd)
241. {
242. structmtd_part*part=PART(mtd);
243. part->master->resume(part->master);
244. }
246. staticintpart_block_isbad(structmtd_info*mtd,loff_tofs)
247. {
248. structmtd_part*part=PART(mtd);
249. if(ofs>=mtd->size)
250. return-EINVAL;
251. ofs+=part->offset;
252. returnpart->master->block_isbad(part->master,ofs);
253. }
254. //標記設備地址壞塊
255. staticintpart_block_markbad(structmtd_info*mtd,loff_tofs)
256. {
257. structmtd_part*part=PART(mtd);
258. intres;
260. if(!(mtd->flags&MTD_WRITEABLE))
261. return-EROFS;
262. if(ofs>=mtd->size)
263. return-EINVAL;
264. ofs+=part->offset;
265. res=part->master->block_markbad(part->master,ofs);
266. if(!res)
267. mtd->ecc_stats.badblocks++;
268. returnres;
269. }

下篇分析具體的MTD設備，字符設備和塊設備，待續........