l(轉)Linux DM9000網絡卡驅動程式完全分析
[置頂] Linux DM9000網絡卡驅動程式完全分析
分類: Linux裝置驅動程式第三版學習筆記 2011-02-26 16:11 3513人閱讀 評論(34) 收藏 舉報說明1:本文分析基於核心原始碼版本為linux-2.6.31
說明2:本文在理解了linux中匯流排、裝置和驅動模型的基礎上加以分析程式碼
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雖然Linux驅動程式應該是和具體的硬體平臺分離的,但是為了更好的理解DM9000的驅動程式,這裡還是結合一下Mini2440開發板,這樣也可以更好的體會如何實現驅動和平臺分離。
本文分成以下幾個部分:
一、Mini2440開發板上DM9000的電氣連線和Mach-mini2440.c檔案的關係。
二、兩個重要的結構體介紹:sk_buff和net_device
三、具體程式碼分析
一、Mini2440開發板上DM9000的電氣連線和Mach-mini2440.c檔案的關係
Mini2440開發板上DM9000與S3C2440的連線關係如下:
其中片選訊號AEN使用了nGCS4,所以網絡卡的記憶體區域在BANK4,也就是從地址0x20000000開始。DM9000的TXD[2:0]作為strap pin在電路圖中是空接的,所以IO base是300H。中斷使用了EINT7。這些內容在Mach檔案中有如下體現:
- #define S3C2410_CS4 (0x20000000)
- #define MACH_MINI2440_DM9K_BASE (S3C2410_CS4 + 0x300)
- static struct resource mini2440_dm9k_resource[] __initdata = {
- [0] = {
- .start = MACH_MINI2440_DM9K_BASE,
- .end = MACH_MINI2440_DM9K_BASE + 3,
- .flags = IORESOURCE_MEM
- },
- [1] = {
- .start = MACH_MINI2440_DM9K_BASE + 4,
- .end = MACH_MINI2440_DM9K_BASE + 7,
- .flags = IORESOURCE_MEM
- },
- [2] = {
- .start = IRQ_EINT7,
- .end = IRQ_EINT7,
- .flags = IORESOURCE_IRQ | IORESOURCE_IRQ_HIGHEDGE,
- }
- };
另外在Mach檔案中還定義了DM9000平臺裝置,裝置名稱為“dm9000”,裝置資源就是上面定義的IO和中斷資源。程式碼清單如下:
[c-sharp] view plain copy- static struct dm9000_plat_data mini2440_dm9k_pdata __initdata = {
- .flags = (DM9000_PLATF_16BITONLY | DM9000_PLATF_NO_EEPROM),
- };
- static struct platform_device mini2440_device_eth __initdata = {
- .name = "dm9000",
- .id = -1,
- .num_resources = ARRAY_SIZE(mini2440_dm9k_resource),
- .resource = mini2440_dm9k_resource,
- .dev = {
- .platform_data = &mini2440_dm9k_pdata,
- },
- };
這個DM9000平臺裝置作為眾多平臺裝置中的一個在扳子初始化的時候就被新增到了總線上。程式碼清單如下:
[c-sharp] view plain copy- MACHINE_START(MINI2440, "MINI2440")
- /* Maintainer: Michel Pollet <[email protected]> */
- .phys_io = S3C2410_PA_UART,
- .io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
- .boot_params = S3C2410_SDRAM_PA + 0x100,
- .map_io = mini2440_map_io,
- .init_machine = mini2440_init, /*初始化函式*/
- .init_irq = s3c24xx_init_irq,
- .timer = &s3c24xx_timer,
- MACHINE_END
- static void __init mini2440_init(void)
- {
- ...
- ...
- platform_add_devices(mini2440_devices, ARRAY_SIZE(mini2440_devices));
- ...
- ...
- }
- static struct platform_device *mini2440_devices[] __initdata = {
- &s3c_device_usb,
- &s3c_device_wdt,
- /* &s3c_device_adc,*/ /* ADC doesn't like living with touchscreen ! */
- &s3c_device_i2c0,
- &s3c_device_rtc,
- &s3c_device_usbgadget,
- &mini2440_device_eth, /*dm9000是眾多平臺裝置中的一個*/
- &mini2440_led1,
- &mini2440_led2,
- &mini2440_led3,
- &mini2440_led4,
- &mini2440_button_device,
- &s3c_device_nand,
- &s3c_device_sdi,
- &s3c_device_iis,
- &mini2440_audio,
- /* &s3c_device_timer[0],*/ /* buzzer pwm, no API for it */
- /* remaining devices are optional */
- };
二、兩個重要的結構體簡單介紹:sk_buff和net_device
*sk_buff
如果把網路傳輸看成是運送貨物的話,那麼sk_buff就是這個“貨物”了,所有經手這個貨物的人都要乾點什麼事兒,要麼加個包裝,要麼印個戳兒等等。收貨的時候就要拆掉這些包裝,得到我們需要的貨物(payload data)。沒有貨物你還運輸什麼呢?由此可見sk_buff的重要性了。關於sk_buff的詳細介紹和幾個操作它的函式,參考本部落格轉載的一篇文章:“linux核心sk_buff的結構分析”,寫得非常明白了。贊一個~
*net_device
又是一個龐大的結構體。好吧,我承認我從來就沒有看全過這個結構體。它在核心中就是指代了一個網路裝置。驅動程式需要在探測的時候分配並初始化這個結構體,然後使用register_netdev來註冊它,這樣就可以把操作硬體的函式與核心掛接在一起。
三、具體程式碼的分析
在順序分析之前先看三個結構體變數和一個自定義的結構體。
* dm9000_driver變數。是platform_driver結構體變數,其中包含了重要的:驅動的名字(用來match)和幾個重要操作函式。
[c-sharp] view plain copy- static struct platform_driver dm9000_driver = {
- .driver = {
- .name = "dm9000",
- .owner = THIS_MODULE,
- },
- .probe = dm9000_probe,
- .remove = __devexit_p(dm9000_drv_remove),
- .suspend = dm9000_drv_suspend,
- .resume = dm9000_drv_resume,
- };
* dm9000_netdev_ops變數。是net_device_ops結構體變數, 其中定義了操作net_device的重要函式,我們在驅動程式中根據需要的操作要填充這些函式。程式碼清單如下:
[c-sharp] view plain copy- static const struct net_device_ops dm9000_netdev_ops = {
- .ndo_open = dm9000_open,
- .ndo_stop = dm9000_stop,
- .ndo_start_xmit = dm9000_start_xmit,
- .ndo_tx_timeout = dm9000_timeout,
- .ndo_set_multicast_list = dm9000_hash_table,
- .ndo_do_ioctl = dm9000_ioctl,
- .ndo_change_mtu = eth_change_mtu,
- .ndo_validate_addr = eth_validate_addr,
- .ndo_set_mac_address = eth_mac_addr,
- #ifdef CONFIG_NET_POLL_CONTROLLER
- .ndo_poll_controller = dm9000_poll_controller,
- #endif
- };
* dm9000_ethtool_ops變數。是ethtool_ops結構體變數,為了支援ethtool,其中的函式主要是用於查詢和設定網絡卡引數(當然也有的驅動程式可能不支援ethtool)。程式碼清單如下:
[c-sharp] view plain copy- static const struct ethtool_ops dm9000_ethtool_ops = {
- .get_drvinfo = dm9000_get_drvinfo,
- .get_settings = dm9000_get_settings,
- .set_settings = dm9000_set_settings,
- .get_msglevel = dm9000_get_msglevel,
- .set_msglevel = dm9000_set_msglevel,
- .nway_reset = dm9000_nway_reset,
- .get_link = dm9000_get_link,
- .get_eeprom_len = dm9000_get_eeprom_len,
- .get_eeprom = dm9000_get_eeprom,
- .set_eeprom = dm9000_set_eeprom,
- };
* board_info結構體。用來儲存晶片相關的一些私有資訊。具體在程式碼中分析。下面是這個結構體的清單。
[c-sharp] view plain copy- /* Structure/enum declaration ------------------------------- */
- typedef struct board_info {
- void __iomem *io_addr; /* Register I/O base address */
- void __iomem *io_data; /* Data I/O address */
- u16 irq; /* IRQ */
- u16 tx_pkt_cnt;
- u16 queue_pkt_len;
- u16 queue_start_addr;
- u16 dbug_cnt;
- u8 io_mode; /* 0:word, 2:byte */
- u8 phy_addr;
- u8 imr_all;
- unsigned int flags;
- unsigned int in_suspend :1;
- int debug_level;
- enum dm9000_type type;
- void (*inblk)(void __iomem *port, void *data, int length);
- void (*outblk)(void __iomem *port, void *data, int length);
- void (*dumpblk)(void __iomem *port, int length);
- struct device *dev; /* parent device */
- struct resource *addr_res; /* resources found */
- struct resource *data_res;
- struct resource *addr_req; /* resources requested */
- struct resource *data_req;
- struct resource *irq_res;
- struct mutex addr_lock; /* phy and eeprom access lock */
- struct delayed_work phy_poll;
- struct net_device *ndev;
- spinlock_t lock;
- struct mii_if_info mii;
- u32 msg_enable;
- } board_info_t;
下面看一下具體程式碼。
分析程式碼還是從init順序開始。
1. 註冊平臺驅動。
主要完成的任務是:將驅動新增到總線上,完成驅動和裝置的match,並執行驅動的probe函式。程式碼清單如下:
[c-sharp] view plain copy- static struct platform_driver dm9000_driver = {
- .driver = {
- .name = "dm9000", /*用這個名字完成驅動和裝置的match*/
- .owner = THIS_MODULE,
- },
- .probe = dm9000_probe,
- .remove = __devexit_p(dm9000_drv_remove),
- .suspend = dm9000_drv_suspend,
- .resume = dm9000_drv_resume,
- };
- static int __init
- dm9000_init(void)
- {
- printk(KERN_INFO "%s Ethernet Driver, V%s/n", CARDNAME, DRV_VERSION);
- return platform_driver_register(&dm9000_driver);
- }
2. probe函式。
主要完成的任務是:探測裝置獲得並儲存資源資訊,根據這些資訊申請記憶體和中斷,最後呼叫register_netdev註冊這個網路裝置。以下是程式碼清單,可以分成幾個部分來看:
1) 首先定義了幾個區域性變數:
struct dm9000_plat_data *pdata = pdev->dev.platform_data;
struct board_info *db; /* Point a board information structure */
struct net_device *ndev;
2) 初始化一個網路裝置。關鍵系統函式:alloc_etherdev()
3) 獲得資源資訊並將其儲存在board_info變數db中。關鍵系統函式:netdev_priv(), platform_get_resource()
4) 根據資源資訊分配記憶體,申請中斷等等, 並將申請後的資源資訊也儲存到db中,並且填充ndev中的引數。 關鍵系統函式:request_mem_region(), ioremap()。 自定義函式:dm9000_set_io()
5) 完成了第4步以後,回顧一下db和ndev中都有了什麼:
struct board_info *db:
addr_res -- 地址資源
data_res -- 資料資源
irq_res -- 中斷資源
addr_req -- 分配的地址記憶體資源
io_addr -- 暫存器I/O基地址
data_req -- 分配的資料記憶體資源
io_data -- 資料I/O基地址
dumpblk -- IO模式
outblk -- IO模式
inblk -- IO模式
lock -- 自旋鎖(已經被初始化)
addr_lock -- 互斥鎖(已經被初始化)
struct net_device *ndev:
base_addr -- 裝置IO地址
irq -- 裝置IRQ號
6) 裝置復位。硬體操作函式dm9000_reset()
7) 讀一下生產商和製造商的ID,應該是0x9000 0A46。 關鍵函式:ior()
8) 讀一下晶片型別。
========以上步驟結束後我們可以認為已經找到了DM9000========
9) 藉助ether_setup()函式來部分初始化ndev。因為對乙太網裝置來講,很多操作與屬性是固定的,核心可以幫助完成。
10) 手動初始化ndev的ops和db的mii部分。
11) (如果有的話)從EEPROM中讀取節點地址。這裡可以看到mini2440這個板子上沒有為DM9000外掛EEPROM,所以讀取出來的全部是0xff。見函式dm9000_read_eeprom。 關於外掛EEPROM,可以參考datasheet上的7.EEPROM Format一節。
12) 很顯然ndev是我們在probe函式中定義的區域性變數,如果我想在其他地方使用它怎麼辦呢? 這就需要把它儲存起來。核心提供了這個方法,使用函式platform_set_drvdata()可以將ndev儲存成平臺匯流排裝置的私有資料。以後再要使用它時只需呼叫platform_get_drvdata()就可以了。
13) 使用register_netdev()註冊ndev。
下面是程式碼清單:
[c-sharp] view plain copy- static int __devinit
- dm9000_probe(struct platform_device *pdev)
- {
- struct dm9000_plat_data *pdata = pdev->dev.platform_data;
- struct board_info *db; /* Point a board information structure */
- struct net_device *ndev;
- const unsigned char *mac_src;
- int ret = 0;
- int iosize;
- int i;
- u32 id_val;
- /* Init network device */
- /*使用alloc_etherdev()來生成一個net_device結構體,並對其公有成員賦值*/
- ndev = alloc_etherdev(sizeof(struct board_info));
- if (!ndev) {
- dev_err(&pdev->dev, "could not allocate device./n");
- return -ENOMEM;
- }
- SET_NETDEV_DEV(ndev, &pdev->dev);
- dev_dbg(&pdev->dev, "dm9000_probe()/n");
- /* setup board info structure */
- db = netdev_priv(ndev);
- memset(db, 0, sizeof(*db));
- db->dev = &pdev->dev;
- db->ndev = ndev;
- spin_lock_init(&db->lock);
- mutex_init(&db->addr_lock);
- INIT_DELAYED_WORK(&db->phy_poll, dm9000_poll_work);
- db->addr_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
- db->data_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
- db->irq_res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
- if (db->addr_res == NULL || db->data_res == NULL ||
- db->irq_res == NULL) {
- dev_err(db->dev, "insufficient resources/n");
- ret = -ENOENT;
- goto out;
- }
- iosize = res_size(db->addr_res);
- db->addr_req = request_mem_region(db->addr_res->start, iosize,
- pdev->name);
- if (db->addr_req == NULL) {
- dev_err(db->dev, "cannot claim address reg area/n");
- ret = -EIO;
- goto out;
- }
- db->io_addr = ioremap(db->addr_res->start, iosize);
- if (db->io_addr == NULL) {
- dev_err(db->dev, "failed to ioremap address reg/n");
- ret = -EINVAL;
- goto out;
- }
- iosize = res_size(db->data_res);
- db->data_req = request_mem_region(db->data_res->start, iosize,
- pdev->name);
- if (db->data_req == NULL) {
- dev_err(db->dev, "cannot claim data reg area/n");
- ret = -EIO;
- goto out;
- }
- db->io_data = ioremap(db->data_res->start, iosize);
- if (db->io_data == NULL) {
- dev_err(db->dev, "failed to ioremap data reg/n");
- ret = -EINVAL;
- goto out;
- }
- /* fill in parameters for net-dev structure */
- ndev->base_addr = (unsigned long)db->io_addr;
- ndev->irq = db->irq_res->start;
- /* ensure at least we have a default set of IO routines */
- dm9000_set_io(db, iosize);
- /* check to see if anything is being over-ridden */
- if (pdata != NULL) {
- /* check to see if the driver wants to over-ride the
- * default IO width */
- if (pdata->flags & DM9000_PLATF_8BITONLY)
- dm9000_set_io(db, 1);
- if (pdata->flags & DM9000_PLATF_16BITONLY)
- dm9000_set_io(db, 2);
- if (pdata->flags & DM9000_PLATF_32BITONLY)
- dm9000_set_io(db, 4);
- /* check to see if there are any IO routine
- * over-rides */
- if (pdata->inblk != NULL)
- db->inblk = pdata->inblk;
- if (pdata->outblk != NULL)
- db->outblk = pdata->outblk;
- if (pdata->dumpblk != NULL)
- db->dumpblk = pdata->dumpblk;
- db->flags = pdata->flags;
- }
- #ifdef CONFIG_DM9000_FORCE_SIMPLE_PHY_POLL
- db->flags |= DM9000_PLATF_SIMPLE_PHY;
- #endif
- dm9000_reset(db);
- /* try multiple times, DM9000 sometimes gets the read wrong */
- for (i = 0; i < 8; i++) {
- id_val = ior(db, DM9000_VIDL);
- id_val |= (u32)ior(db, DM9000_VIDH) << 8;
- id_val |= (u32)ior(db, DM9000_PIDL) << 16;
- id_val |= (u32)ior(db, DM9000_PIDH) << 24;
- if (id_val == DM9000_ID)
- break;
- dev_err(db->dev, "read wrong id 0x%08x/n", id_val);
- }
- if (id_val != DM9000_ID) {
- dev_err(db->dev, "wrong id: 0x%08x/n", id_val);
- ret = -ENODEV;
- goto out;
- }
- /* Identify what type of DM9000 we are working on */
- id_val = ior(db, DM9000_CHIPR);
- dev_dbg(db->dev, "dm9000 revision 0x%02x/n", id_val);
- switch (id_val) {
- case CHIPR_DM9000A:
- db->type = TYPE_DM9000A;
- break;
- case CHIPR_DM9000B:
- db->type = TYPE_DM9000B;
- break;
- default:
- dev_dbg(db->dev, "ID %02x => defaulting to DM9000E/n", id_val);
- db->type = TYPE_DM9000E;
- }
- /* from this point we assume that we have found a DM9000 */
- /* driver system function */
- ether_setup(ndev);
- ndev->netdev_ops = &dm9000_netdev_ops;
- ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
- ndev->ethtool_ops = &dm9000_ethtool_ops;
- db->msg_enable = NETIF_MSG_LINK;
- db->mii.phy_id_mask = 0x1f;
- db->mii.reg_num_mask = 0x1f;
- db->mii.force_media = 0;
- db->mii.full_duplex = 0;
- db->mii.dev = ndev;
- db->mii.mdio_read = dm9000_phy_read;
- db->mii.mdio_write = dm9000_phy_write;
- mac_src = "eeprom";
- /* try reading the node address from the attached EEPROM */
- for (i = 0; i < 6; i += 2)
- dm9000_read_eeprom(db, i / 2, ndev->dev_addr+i);
- if (!is_valid_ether_addr(ndev->dev_addr) && pdata != NULL) {
- mac_src = "platform data";
- memcpy(ndev->dev_addr, pdata->dev_addr, 6);
- }
- if (!is_valid_ether_addr(ndev->dev_addr)) {
- /* try reading from mac */
- mac_src = "chip";
- for (i = 0; i < 6; i++)
- ndev->dev_addr[i] = ior(db, i+DM9000_PAR);
- }
- if (!is_valid_ether_addr(ndev->dev_addr))
- dev_warn(db->dev, "%s: Invalid ethernet MAC address. Please "
- "set using ifconfig/n", ndev->name);
- platform_set_drvdata(pdev, ndev);
- ret = register_netdev(ndev);
- if (ret == 0)
- printk(KERN_INFO "%s: dm9000%c at %p,%p IRQ %d MAC: %pM (%s)/n",
- ndev->name, dm9000_type_to_char(db->type),
- db->io_addr, db->io_data, ndev->irq,
- ndev->dev_addr, mac_src);
- return 0;
- out:
- dev_err(db->dev, "not found (%d)./n", ret);
- dm9000_release_board(pdev, db);
- free_netdev(ndev);
- return ret;
- }
3. platform_driver的remove, suspend和resume的實現
remove函式的功能是把裝置從核心中移除,釋放記憶體區域。該函式在解除安裝模組時被呼叫。程式碼清單如下:
[c-sharp] view plain copy- static int __devexit
- dm9000_drv_remove(struct platform_device *pdev)
- {
- struct net_device *ndev = platform_get_drvdata(pdev);
- platform_set_drvdata(pdev, NULL);
- unregister_netdev(ndev);
- dm9000_release_board(pdev, (board_info_t *) netdev_priv(ndev));
- free_netdev(ndev); /* free device structure */
- dev_dbg(&pdev->dev, "released and freed device/n");
- return 0;
- }
suspend函式並不真正把裝置從核心中移除,而只是標誌裝置為removed狀態,並設定掛起標誌位,最後關閉裝置。程式碼清單如下:
[c-sharp] view plain copy- static int
- dm9000_drv_suspend(struct platform_device *dev, pm_message_t state)
- {
- struct net_device *ndev = platform_get_drvdata(dev);
- board_info_t *db;
- if (ndev) {
- db = netdev_priv(ndev);
- db->in_suspend = 1;
- if (netif_running(ndev)) {
- netif_device_detach(ndev);
- dm9000_shutdown(ndev);
- }
- }
- return 0;
- }
resume函式將掛起的裝置復位並初始化,軟後將裝置標誌為attached狀態,並設定掛起標誌位。程式碼清單如下:
[c-sharp] view plain copy- static int
- dm9000_drv_resume(struct platform_device *dev)
- {
- struct net_device *ndev = platform_get_drvdata(dev);
- board_info_t *db = netdev_priv(ndev);
- if (ndev) {
- if (netif_running(ndev)) {
- dm9000_reset(db);
- dm9000_init_dm9000(ndev);
- netif_device_attach(ndev);
- }
- db->in_suspend = 0;
- }
- return 0;
- }
4. 下面看一下用於填充net_device中netdev_ops和ethtool_ops的一些函式。
程式碼在上面已經寫出來了,為了看著方便在下面再寫一遍,可以看出雖然mini2440的板子上沒有為DM9000掛EEPROM,但這裡還是定義了操作EEPROM的函式。就是說寫驅動的時候是不考慮具體的板子的,你板子用不用是你的事,但是我們的驅動應該所有的功能都考慮進去。這也體現了驅動和平臺分離的設計思想。
[c-sharp] view plain copy- static const struct net_device_ops dm9000_netdev_ops = {
- .ndo_open = dm9000_open,
- .ndo_stop = dm9000_stop,
- .ndo_start_xmit = dm9000_start_xmit,
- .ndo_tx_timeout = dm9000_timeout,
- .ndo_set_multicast_list = dm9000_hash_table,
- .ndo_do_ioctl = dm9000_ioctl,
- .ndo_change_mtu = eth_change_mtu,
- .ndo_validate_addr = eth_validate_addr,
- .ndo_set_mac_address = eth_mac_addr,
- #ifdef CONFIG_NET_POLL_CONTROLLER
- .ndo_poll_controller = dm9000_poll_controller,
- #endif
- };
- static const struct ethtool_ops dm9000_ethtool_ops = {
- .get_drvinfo = dm9000_get_drvinfo,
- .get_settings = dm9000_get_settings,
- .set_settings = dm9000_set_settings,
- .get_msglevel = dm9000_get_msglevel,
- .set_msglevel = dm9000_set_msglevel,
- .nway_reset = dm9000_nway_reset,
- .get_link = dm9000_get_link,
- .get_eeprom_len = dm9000_get_eeprom_len,
- .get_eeprom = dm9000_get_eeprom,
- .set_eeprom = dm9000_set_eeprom,
- };
*dm9000_open()
進行的工作有 向核心註冊中斷,復位並初始化dm9000,檢查MII介面,使能傳輸等。程式碼清單如下:
[c-sharp] view plain copy- /*
- * Open the interface.
- * The interface is opened whenever "ifconfig" actives it.
- */
- static int
- dm9000_open(struct net_device *dev)
- {
- board_info_t *db = netdev_priv(dev);
- unsigned long irqflags = db->irq_res->flags & IRQF_TRIGGER_MASK;
- if (netif_msg_ifup(db))
- dev_dbg(db->dev, "enabling %s/n", dev->name);
- /* If there is no IRQ type specified, default to something that
- * may work, and tell the user that this is a problem */
- if (irqflags == IRQF_TRIGGER_NONE)
- dev_warn(db->dev, "WARNING: no IRQ resource flags set./n");
- irqflags |= IRQF_SHARED;
- if (request_irq(dev->irq, &dm9000_interrupt, irqflags, dev->name, dev))/*註冊一箇中斷,中斷處理函式為dm9000_interrupt()*/
- return -EAGAIN;
- /* Initialize DM9000 board */
- dm9000_reset(db);
- dm9000_init_dm9000(dev);
- /* Init driver variable */
- db->dbug_cnt = 0;
- mii_check_media(&db->mii, netif_msg_link(db), 1);
- netif_start_queue(dev);
- dm9000_schedule_poll(db);/*之前在probe函式中已經使用INIT_DELAYED_WORK來初始化一個延遲工作佇列並關聯了一個操作函式dm9000_poll_work(), 此時執行schedule來呼叫這個函式*/
- return 0;
- }
*dm9000_stop()
做的工作基本上和open相反。程式碼清單如下:
[c-sharp] view plain copy- /*
- * Stop the interface.
- * The interface is stopped when it is brought.
- */
- static int
- dm9000_stop(struct net_device *ndev)
- {
- board_info_t *db = netdev_priv(ndev);
- if (netif_msg_ifdown(db))
- dev_dbg(db->dev, "shutting down %s/n", ndev->name);
- cancel_delayed_work_sync(&db->phy_poll); /*殺死延遲工作佇列phy_poll*/
- /*停止傳輸並清空carrier*/
- netif_stop_queue(ndev);
- netif_carrier_off(ndev);
- /* free interrupt */
- free_irq(ndev->irq, ndev);
- dm9000_shutdown(ndev);
- return 0;
- }
*dm9000_start_xmit()
重要的傳送資料包函式。從上層傳送sk_buff包。在看程式碼之前先來看一下DM9000是如何傳送資料包的。
如上圖所示,在DM9000內部SRAM中,地址0x0000~0x0BFF是TX Buffer, 地址0x0C00~0x3FFF是RX Buffer。在傳送一個包之前,包中的有效資料必須先被儲存到TX Buffer中並且使用輸出埠命令來選擇MWCMD暫存器。包的長度定義在TXPLL和TXPLH中。最後設定TXCR暫存器的bit[0] TXREQ來自動傳送包。如果設定了IMR暫存器的PTM位,則DM9000會產生一箇中斷觸發在ISR暫存器的bit[1]=PTS=1, 同時設定一個完成標誌在NSR暫存器的bit[2]=TX1END或者 bit[3]=TX2END,表示包已經發送完了。傳送一個包的具體步驟如下:
Step 1: 檢查儲存資料寬度。通過讀取中斷狀態暫存器(ISR)的bit[7:6]來確定是8bit,16bit還是32bit。
Step 2: 寫資料到TX SRAM中。
Step 3: 寫傳輸長度到TXPLL和TXPLH暫存器中。
Step 4: 設定TXCR暫存器的bit[0]TXREQ來開始傳送一個包。
程式碼清單如下,讓我們看看在獲得自旋鎖這段期間都幹了些什麼:
[c-sharp] view plain copy- /*
- * Hardware start transmission.
- * Send a packet to media from the upper layer.
- */
- static int
- dm9000_start_xmit(struct sk_buff *skb, struct net_device *dev)
- {
- unsigned long flags;
- board_info_t *db = netdev_priv(dev);
- dm9000_dbg(db, 3, "%s:/n", __func__);
- if (db->tx_pkt_cnt > 1)
- return NETDEV_TX_BUSY;
- /*獲得自旋鎖*/
- spin_lock_irqsave(&db->lock, flags);
- /* Move data to DM9000&nbs