Linux設備驅動工程師之路——DM9000網卡驅動程序分析

1.模塊初始化

1. static struct platform_driver dm9000_driver = {
2. .driver = {
3. .name = "dm9000",
4. .owner = THIS_MODULE,
5. },
6. .probe = dm9000_probe,
7. .remove = __devexit_p(dm9000_drv_remove),
8. .suspend = dm9000_drv_suspend,
9. .resume = dm9000_drv_resume,
10. };
12. static int __init
13. dm9000_init(void)
14. {
15. printk(KERN_INFO "%s Ethernet Driver, V%s\n", CARDNAME, DRV_VERSION);
17. return platform_driver_register(&dm9000_driver);
18. }

模塊初始化完成了基於platfrom平台的DM9000網卡驅動的注冊，當DM9000網卡找到其對應的能處理的platform設備後調用probe函數。

2.DM9000網卡初始化

在probe函數中完成了對DM9000網卡的初始化

DM9000的特性：DM9000地址信號和數據信號復用使用CMD引腳區分它們（CMD為低是讀寫DM900地址寄存器，CMD為高時讀寫DM9000數據寄存器），訪問DM9000內部寄存器時，先將CMD置低，寫DM900地址寄存器，然後將CMD置高，讀寫DM9000數據寄存器。

1. static int __devinit
2. dm9000_probe(struct platform_device *pdev)
3. {
4. struct dm9000_plat_data *pdata = pdev->dev.platform_data;
5. struct board_info *db; /* Point a board information structure */
6. struct net_device *ndev;
7. const unsigned char *mac_src;
8. int ret = 0;
9. int iosize;
10. int i;
11. u32 id_val;
13. /* Init network device */
14. //申請net_device結構
15. ndev = alloc_etherdev(sizeof(struct board_info));
16. if (!ndev) {
17. dev_err(&pdev->dev, "could not allocate device.\n");
18. return -ENOMEM;
19. }
22. //將net_device的parent指針指向platform_device對象，表示該設備掛載platform設備上。
23. SET_NETDEV_DEV(ndev, &pdev->dev);
25. dev_dbg(&pdev->dev, "dm9000_probe()\n");
27. /* setup board info structure */
28. //獲取net_device私有數據結構指針
29. db = netdev_priv(ndev);
30. memset(db, 0, sizeof(*db));
32. //設置相關設備
33. db->dev = &pdev->dev;
34. db->ndevndev = ndev;
36. spin_lock_init(&db->lock);
37. mutex_init(&db->addr_lock);
39. INIT_DELAYED_WORK(&db->phy_poll, dm9000_poll_work);
41. //獲取平台設備資源。包括DM9000地址寄存器地址，DM9000數據寄存器地址，和DM900所占用的中斷號
43. db->addr_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
44. db->data_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
45. db->irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
47. if (db->addr_res == NULL || db->data_res == NULL ||
48. db->irq_res == NULL) {
49. dev_err(db->dev, "insufficient resources\n");
50. ret = -ENOENT;
51. goto out;
52. }
54. //申請地址寄存器IO內存區域並映射
55. iosize = res_size(db->addr_res);
56. db->addr_req = request_mem_region(db->addr_res->start, iosize,
57. pdev->name);
59. if (db->addr_req == NULL) {
60. dev_err(db->dev, "cannot claim address reg area\n");
61. ret = -EIO;
62. goto out;
63. }
65. db->io_addr = ioremap(db->addr_res->start, iosize);
67. if (db->io_addr == NULL) {
68. dev_err(db->dev, "failed to ioremap address reg\n");
69. ret = -EINVAL;
70. goto out;
71. }
73. //申請數據寄存器IO內存區域並映射
74. iosize = res_size(db->data_res);
75. db->data_req = request_mem_region(db->data_res->start, iosize,
76. pdev->name);
78. if (db->data_req == NULL) {
79. dev_err(db->dev, "cannot claim data reg area\n");
80. ret = -EIO;
81. goto out;
82. }
84. db->io_data = ioremap(db->data_res->start, iosize);
86. if (db->io_data == NULL) {
87. dev_err(db->dev, "failed to ioremap data reg\n");
88. ret = -EINVAL;
89. goto out;
90. }
92. /* fill in parameters for net-dev structure */
93. ndev->base_addr = (unsigned long)db->io_addr;
94. ndev->irq = db->irq_res->start;
96. //設置數據位寬
97. /* ensure at least we have a default set of IO routines */
98. dm9000_set_io(db, iosize);
100. /* check to see if anything is being over-ridden */
101. if (pdata != NULL) {
102. /* check to see if the driver wants to over-ride the
103. * default IO width */
105. if (pdata->flags & DM9000_PLATF_8BITONLY)
106. dm9000_set_io(db, 1);
108. if (pdata->flags & DM9000_PLATF_16BITONLY)
109. dm9000_set_io(db, 2);
111. if (pdata->flags & DM9000_PLATF_32BITONLY)
112. dm9000_set_io(db, 4);
114. /* check to see if there are any IO routine
115. * over-rides */
117. if (pdata->inblk != NULL)
118. db->inblk = pdata->inblk;
120. if (pdata->outblk != NULL)
121. db->outblk = pdata->outblk;
123. if (pdata->dumpblk != NULL)
124. db->dumpblk = pdata->dumpblk;
126. db->flags = pdata->flags;
127. }
129. #ifdef CONFIG_DM9000_FORCE_SIMPLE_PHY_POLL
130. db->flags |= DM9000_PLATF_SIMPLE_PHY;
131. #endif
133. //復位網卡芯片
134. dm9000_reset(db);
136. //讀取設備ID，判斷是否是驅動能夠處理的網卡芯片
137. /* try multiple times, DM9000 sometimes gets the read wrong */
138. for (i = 0; i < 8; i++) {
139. id_val = ior(db, DM9000_VIDL);
140. id_val |= (u32)ior(db, DM9000_VIDH) << 8;
141. id_val |= (u32)ior(db, DM9000_PIDL) << 16;
142. id_val |= (u32)ior(db, DM9000_PIDH) << 24;
144. if (id_val == DM9000_ID)
145. break;
146. dev_err(db->dev, "read wrong id 0x%08x\n", id_val);
147. }
149. if (id_val != DM9000_ID) {
150. dev_err(db->dev, "wrong id: 0x%08x\n", id_val);
151. ret = -ENODEV;
152. goto out;
153. }
155. /* Identify what type of DM9000 we are working on */
157. id_val = ior(db, DM9000_CHIPR);
158. dev_dbg(db->dev, "dm9000 revision 0x%02x\n", id_val);
160. switch (id_val) {
161. case CHIPR_DM9000A:
162. db->type = TYPE_DM9000A;
163. break;
164. case CHIPR_DM9000B:
165. db->type = TYPE_DM9000B;
166. break;
167. default:
168. dev_dbg(db->dev, "ID %02x => defaulting to DM9000E\n", id_val);
169. db->type = TYPE_DM9000E;
170. }
172. /* from this point we assume that we have found a DM9000 */
174. /* driver system function */
175. ether_setup(ndev);
177. //設置網卡芯片的接口函數
178. ndev->open = &dm9000_open;
179. ndev->hard_start_xmit = &dm9000_start_xmit;
180. ndev->tx_timeout = &dm9000_timeout;
181. ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
182. ndev->stop = &dm9000_stop;
183. ndev->set_multicast_list = &dm9000_hash_table;
184. ndev->ethtool_ops = &dm9000_ethtool_ops;
185. ndev->do_ioctl = &dm9000_ioctl;
187. #ifdef CONFIG_NET_POLL_CONTROLLER
188. ndev->poll_controller = &dm9000_poll_controller;
189. #endif
191. db->msg_enable = NETIF_MSG_LINK;
192. db->mii.phy_id_mask = 0x1f;
193. db->mii.reg_num_mask = 0x1f;
194. db->mii.force_media = 0;
195. db->mii.full_duplex = 0;
196. db->mii.dev = ndev;
197. db->mii.mdio_read = dm9000_phy_read;
198. db->mii.mdio_write = dm9000_phy_write;
200. mac_src = "eeprom";
202. //從EEPROM中讀取MAC地址填充dev_addr
203. /* try reading the node address from the attached EEPROM */
204. for (i = 0; i < 6; i += 2)
205. dm9000_read_eeprom(db, i / 2, ndev->dev_addr+i);
207. if (!is_valid_ether_addr(ndev->dev_addr) && pdata != NULL) {
208. mac_src = "platform data";
209. memcpy(ndev->dev_addr, pdata->dev_addr, 6);
210. }
212. if (!is_valid_ether_addr(ndev->dev_addr)) {
213. /* try reading from mac */
215. mac_src = "chip";
216. for (i = 0; i < 6; i++)
217. ndev->dev_addr[i] = ior(db, i+DM9000_PAR);
218. }
220. if (!is_valid_ether_addr(ndev->dev_addr))
221. dev_warn(db->dev, "%s: Invalid ethernet MAC address. Please "
222. "set using ifconfig\n", ndev->name);
224. //設置平台設備驅動的dev成員為ndev。
225. platform_set_drvdata(pdev, ndev);
227. //注冊網絡設備驅動
228. ret = register_netdev(ndev);
230. if (ret == 0)
231. printk(KERN_INFO "%s: dm9000%c at %p,%p IRQ %d MAC: %pM (%s)\n",
232. ndev->name, dm9000_type_to_char(db->type),
233. db->io_addr, db->io_data, ndev->irq,
234. ndev->dev_addr, mac_src);
235. return 0;
237. out:
238. dev_err(db->dev, "not found (%d).\n", ret);
240. dm9000_release_board(pdev, db);
241. free_netdev(ndev);
243. return ret;
244. }

我們在來看看讀寫網卡寄存器所用的ior和iow

1. static u8
2. ior(board_info_t * db, int reg)
3. {
4. writeb(reg, db->io_addr);
5. return readb(db->io_data);
6. }
8. static void
9. iow(board_info_t * db, int reg, int value)
10. {
11. writeb(reg, db->io_addr);
12. writeb(value, db->io_data);
13. }

可以看得出是先將要訪問的寄存器地址寫入到地址寄存器，然後在將數據寫入到數據寄存器。地址。