DM9000是開發板經采用的網絡芯片，是一種高度集成而且功耗很低的高速網絡控制器，可以和CPU直連，支持10/100M以太網連接，芯片內部自帶16K SARM(3KB用來發送，13KB用來接收).

1.模塊初始化

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,??

};??

static?int?__init??

dm9000_init(void)??

{??

printk(KERN_INFO?"%s?Ethernet?Driver,?V%s\n",?CARDNAME,?DRV_VERSION);??

return?platform_driver_register(&dm9000_driver);??

}??

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,};static int __initdm9000_init(void){printk(KERN_INFO "%s Ethernet Driver, V%s\n", CARDNAME, DRV_VERSION);return platform_driver_register(&dm9000_driver);}

模塊初始化完成了基于platfrom平臺的DM9000網卡驅動的注冊，當DM9000網卡找到其對應的能處理的platform設備后調用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，然后將CMD置高，讀寫DM9000數據寄存器。

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?*/??

//申請net_device結構??

ndev?=?alloc_etherdev(sizeof(struct?board_info));??

if?(!ndev)?{??

dev_err(&pdev->dev,?"could?not?allocate?device.\n");??

return?-ENOMEM;??

}??

//將net_device的parent指針指向platform_device對象，表示該設備掛載platform設備上。??

SET_NETDEV_DEV(ndev,?&pdev->dev);???

dev_dbg(&pdev->dev,?"dm9000_probe()\n");??

/*?setup?board?info?structure?*/??

//獲取net_device私有數據結構指針??

db?=?netdev_priv(ndev);??

memset(db,?0,?sizeof(*db));??

//設置相關設備??

db->dev?=?&pdev->dev;??

db->ndevndev?=?ndev;??

spin_lock_init(&db->lock);??

mutex_init(&db->addr_lock);??

INIT_DELAYED_WORK(&db->phy_poll,?dm9000_poll_work);??

//獲取平臺設備資源。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??

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;??

}??

//申請地址寄存器IO內存區域并映射??

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;??

}??

//申請數據寄存器IO內存區域并映射??

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;??

//設置數據位寬??

/*?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??

//復位網卡芯片??

dm9000_reset(db);??

//讀取設備ID，判斷是否是驅動能夠處理的網卡芯片??

/*?try?multiple?times,?DM9000?sometimes?gets?the?read?wrong?*/??

for?(i?=?0;?i?

id_val??=?ior(db,?DM9000_VIDL);??

id_val?|=?(u32)ior(db,?DM9000_VIDH)?<

id_val?|=?(u32)ior(db,?DM9000_PIDL)?<

id_val?|=?(u32)ior(db,?DM9000_PIDH)?<

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);??

//設置網卡芯片的接口函數??

ndev->open????????=?&dm9000_open;??

ndev->hard_start_xmit????=?&dm9000_start_xmit;??

ndev->tx_timeout?????????=?&dm9000_timeout;??

ndev->watchdog_timeo?=?msecs_to_jiffies(watchdog);??

ndev->stop????????=?&dm9000_stop;??

ndev->set_multicast_list?=?&dm9000_hash_table;??

ndev->ethtool_ops?????=?&dm9000_ethtool_ops;??

ndev->do_ioctl????????=?&dm9000_ioctl;??

#ifdef?CONFIG_NET_POLL_CONTROLLER??

ndev->poll_controller?????=?&dm9000_poll_controller;??

#endif??

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";??

//從EEPROM中讀取MAC地址填充dev_addr??

/*?try?reading?the?node?address?from?the?attached?EEPROM?*/??

for?(i?=?0;?i?

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?

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);??

//設置平臺設備驅動的dev成員為ndev。??

platform_set_drvdata(pdev,?ndev);??

//注冊網絡設備驅動??

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;??

}??

static int __devinitdm9000_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 *///申請net_device結構ndev = alloc_etherdev(sizeof(struct board_info));if (!ndev) {dev_err(&pdev->dev, "could not allocate device.\n");return -ENOMEM;}//將net_device的parent指針指向platform_device對象，表示該設備掛載platform設備上。SET_NETDEV_DEV(ndev, &pdev->dev);dev_dbg(&pdev->dev, "dm9000_probe()\n");/* setup board info structure *///獲取net_device私有數據結構指針db = netdev_priv(ndev);memset(db, 0, sizeof(*db));//設置相關設備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);//獲取平臺設備資源。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;}//申請地址寄存器IO內存區域并映射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;}//申請數據寄存器IO內存區域并映射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;//設置數據位寬/* 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_POLLdb->flags |= DM9000_PLATF_SIMPLE_PHY;#endif//復位網卡芯片dm9000_reset(db);//讀取設備ID，判斷是否是驅動能夠處理的網卡芯片/* 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);//設置網卡芯片的接口函數ndev->open = &dm9000_open;ndev->hard_start_xmit = &dm9000_start_xmit;ndev->tx_timeout = &dm9000_timeout;ndev->watchdog_timeo = msecs_to_jiffies(watchdog);ndev->stop = &dm9000_stop;ndev->set_multicast_list = &dm9000_hash_table;ndev->ethtool_ops = &dm9000_ethtool_ops;ndev->do_ioctl = &dm9000_ioctl;#ifdef CONFIG_NET_POLL_CONTROLLERndev->poll_controller = &dm9000_poll_controller;#endifdb->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";//從EEPROM中讀取MAC地址填充dev_addr/* 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);//設置平臺設備驅動的dev成員為ndev。platform_set_drvdata(pdev, ndev);//注冊網絡設備驅動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;}

我們在來看看讀寫網卡寄存器所用的ior和iow

static?u8??

ior(board_info_t?*?db,?int?reg)??

{??

writeb(reg,?db->io_addr);??

return?readb(db->io_data);??

}??

static?void??

iow(board_info_t?*?db,?int?reg,?int?value)??

{??

writeb(reg,?db->io_addr);??

writeb(value,?db->io_data);??

}??

static u8ior(board_info_t * db, int reg){writeb(reg, db->io_addr);return readb(db->io_data);}static voidiow(board_info_t * db, int reg, int value){writeb(reg, db->io_addr);writeb(value, db->io_data);}

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，然后在將數據寫入到數據寄存器。地址。

3.打開網卡

在linux終端下使用ifconfig命令時調用net_device的open函數打開網卡設備

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;??

//申請中斷??

if?(request_irq(dev->irq,?&dm9000_interrupt,?irqflags,?dev->name,?dev))??

return?-EAGAIN;??

/*?Initialize?DM9000?board?*/??

//復位網卡芯片??

dm9000_reset(db);??

//初始化網卡（相關寄存器設置）??

dm9000_init_dm9000(dev);??

/*?Init?driver?variable?*/??

db->dbug_cnt?=?0;??

mii_check_media(&db->mii,?netif_msg_link(db),?1);??

//打開發送隊列??

netif_start_queue(dev);??

//調度發送隊列開始工作??

dm9000_schedule_poll(db);??

return?0;??

}???

static intdm9000_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;//申請中斷if (request_irq(dev->irq, &dm9000_interrupt, irqflags, dev->name, dev))return -EAGAIN;/* Initialize DM9000 board *///復位網卡芯片dm9000_reset(db);//初始化網卡（相關寄存器設置）dm9000_init_dm9000(dev);/* Init driver variable */db->dbug_cnt = 0;mii_check_media(&db->mii, netif_msg_link(db), 1);//打開發送隊列netif_start_queue(dev);//調度發送隊列開始工作dm9000_schedule_poll(db);return 0;}

4.數據發送

下面說一下DM9000A中的存儲部分，DM9000A內部有一個4K Dword SRAM，其中3KB是作為發送，16KB作為接收，如下圖所示。其中0x0000~0x0BFF是傳說中的TX buffer(TX buffer中只能存放兩個包)，0x0C00~0x3FFF是RX buffer。因此在寫內存操作時，當IMR的第7位被設置，如果到達了地址的結尾比如到了3KB，則回卷到0。相似的方式，在讀操作中，當IMR的第7位被設置如果到達了地址的結尾比如16K，則回卷到0x0C00。

DM9000的TX RAM可以同時放兩個包，可以第9行代碼中看出如果大于TXRAM中的包大于2則返回，DM9000會先發送第一個包，然后再發第二個包。

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__);??

//如果TX?RAM中的包大于2個包則返回??

if?(db->tx_pkt_cnt?>?1)??

return?1;??

spin_lock_irqsave(&db->lock,?flags);??

*MWCMD是Memory?data?write?command?with?address?increment?Register(F8H)???

*將要訪問的TXRAM地址寫入地址寄存器。??

/*?Move?data?to?DM9000?TX?RAM?*/??

writeb(DM9000_MWCMD,?db->io_addr);??

//拷貝數據到TXRAM??

(db->outblk)(db->io_data,?skb->data,?skb->len);??

dev->stats.tx_bytes?+=?skb->len;??

db->tx_pkt_cnt++;//增加數據包計數，這個值會在發送完成中斷時進行自減??

如果是第一個包則直接發送??

/*?TX?control:?First?packet?immediately?send,?second?packet?queue?*/??

if?(db->tx_pkt_cnt?==?1)?{??

/*?Set?TX?length?to?DM9000?*/??

/*把數據的長度填到TXPLL(發送包長度低字節)和TXPLH(發送包長度高字節)中*/????

iow(db,?DM9000_TXPLL,?skb->len);????

iow(db,?DM9000_TXPLH,?skb->len?>>?8);????

/*置發送控制寄存器(TX?Control?Register)的發送請求位TXREQ(Auto?clears?after?sending?completely)，這樣就可以發送出去了*/???

/*???

*記下此時的時間，這里起一個時間戳的作用，之后的超時會用到。如果當前的系統時間超過設備的trans_start時間???

*至少一個超時周期，網絡層將最終調用驅動程序的tx_timeout。那個這個"一個超時周期"又是什么呢？這個是我們在???

*probe函數中設置的,ndev->watchdog_timeo?=?msecs_to_jiffies(watchdog);???

*/??

dev->trans_start?=?jiffies;??/*?save?the?time?stamp?*/??

}?else?{??????????

//如果是第二個包，則暫時不發送，等待第一個包發送完成時tx_pkt_cnt減為1的時候再發送。??

/*?Second?packet?*/??

db->queue_pkt_len?=?skb->len;??

netif_stop_queue(dev);//停止發送隊列??

}??

spin_unlock_irqrestore(&db->lock,?flags);??

/*?free?this?SKB?*/??

dev_kfree_skb(skb);??

return?0;??

}??

static intdm9000_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__);//如果TX RAM中的包大于2個包則返回if (db->tx_pkt_cnt > 1)return 1;spin_lock_irqsave(&db->lock, flags);*MWCMD是Memory data write command with address increment Register(F8H)*將要訪問的TXRAM地址寫入地址寄存器。/* Move data to DM9000 TX RAM */writeb(DM9000_MWCMD, db->io_addr);//拷貝數據到TXRAM(db->outblk)(db->io_data, skb->data, skb->len);dev->stats.tx_bytes += skb->len;db->tx_pkt_cnt++;//增加數據包計數，這個值會在發送完成中斷時進行自減如果是第一個包則直接發送/* TX control: First packet immediately send, second packet queue */if (db->tx_pkt_cnt == 1) {/* Set TX length to DM9000 *//*把數據的長度填到TXPLL(發送包長度低字節)和TXPLH(發送包長度高字節)中*/iow(db, DM9000_TXPLL, skb->len);iow(db, DM9000_TXPLH, skb->len >> 8);/*置發送控制寄存器(TX Control Register)的發送請求位TXREQ(Auto clears after sending completely)，這樣就可以發送出去了*//**記下此時的時間，這里起一個時間戳的作用，之后的超時會用到。如果當前的系統時間超過設備的trans_start時間*至少一個超時周期，網絡層將最終調用驅動程序的tx_timeout。那個這個"一個超時周期"又是什么呢？這個是我們在*probe函數中設置的,ndev->watchdog_timeo = msecs_to_jiffies(watchdog);*/dev->trans_start = jiffies;/* save the time stamp */} else {//如果是第二個包，則暫時不發送，等待第一個包發送完成時tx_pkt_cnt減為1的時候再發送。/* Second packet */db->queue_pkt_len = skb->len;netif_stop_queue(dev);//停止發送隊列}spin_unlock_irqrestore(&db->lock, flags);/* free this SKB */dev_kfree_skb(skb);return 0;}

4.中斷

static?irqreturn_t?dm9000_interrupt(intirq,?void?*dev_id)??

{??

structnet_device?*dev?=?dev_id;??

board_info_t*db?=?netdev_priv(dev);??

intint_status;??

unsignedlong?flags;??

u8reg_save;??

dm9000_dbg(db,3,?"entering?%s\n",?__func__);??

/*A?real?interrupt?coming?*/??

//禁止所用中斷??

/*holders?of?db->lock?must?always?block?IRQs?*/??

spin_lock_irqsave(&db->lock,flags);??

//保存寄存器地址??

/*Save?previous?register?address?*/??

reg_save=?readb(db->io_addr);??

//禁止DM9000的所有中斷??

/*Disable?all?interrupts?*/??

iow(db,DM9000_IMR,?IMR_PAR);??

/*Got?DM9000?interrupt?status?*/??

//獲取中斷狀態寄存器的值??

int_status=?ior(db,?DM9000_ISR);?/*?Got?ISR?*/??

iow(db,DM9000_ISR,?int_status);?/*?Clear?ISRstatus?*/??

if(netif_msg_intr(db))??

dev_dbg(db->dev,"interrupt?status?%02x\n",?int_status);??

/*Received?the?coming?packet?*/??

//如果是讀取中斷，則開始讀取??

if(int_status?&?ISR_PRS)??

dm9000_rx(dev);??

/*Trnasmit?Interrupt?check?*/??

//是發送完成中斷則處理發送完成后的事情??

if(int_status?&?ISR_PTS)??

dm9000_tx_done(dev,db);??

if(db->type?!=?TYPE_DM9000E)?{??

if(int_status?&?ISR_LNKCHNG)?{??

/*fire?a?link-change?request?*/??

schedule_delayed_work(&db->phy_poll,1);??

}??

}??

/*Re-enable?interrupt?mask?*/??

//重新打開DM9000的內部中斷??

iow(db,DM9000_IMR,?db->imr_all);??

/*Restore?previous?register?address?*/??

//恢復寄存器的值??

writeb(reg_save,db->io_addr);??

//重新允許所有中斷??

spin_unlock_irqrestore(&db->lock,flags);??

returnIRQ_HANDLED;??

}??

static irqreturn_t dm9000_interrupt(intirq, void *dev_id){structnet_device *dev = dev_id;board_info_t*db = netdev_priv(dev);intint_status;unsignedlong flags;u8reg_save;dm9000_dbg(db,3, "entering %s\n", __func__);/*A real interrupt coming *///禁止所用中斷/*holders of db->lock must always block IRQs */spin_lock_irqsave(&db->lock,flags);//保存寄存器地址/*Save previous register address */reg_save= readb(db->io_addr);//禁止DM9000的所有中斷/*Disable all interrupts */iow(db,DM9000_IMR, IMR_PAR);/*Got DM9000 interrupt status *///獲取中斷狀態寄存器的值int_status= ior(db, DM9000_ISR); /* Got ISR */iow(db,DM9000_ISR, int_status); /* Clear ISRstatus */if(netif_msg_intr(db))dev_dbg(db->dev,"interrupt status %02x\n", int_status);/*Received the coming packet *///如果是讀取中斷，則開始讀取if(int_status & ISR_PRS)dm9000_rx(dev);/*Trnasmit Interrupt check *///是發送完成中斷則處理發送完成后的事情if(int_status & ISR_PTS)dm9000_tx_done(dev,db);if(db->type != TYPE_DM9000E) {if(int_status & ISR_LNKCHNG) {/*fire a link-change request */schedule_delayed_work(&db->phy_poll,1);}}/*Re-enable interrupt mask *///重新打開DM9000的內部中斷iow(db,DM9000_IMR, db->imr_all);/*Restore previous register address *///恢復寄存器的值writeb(reg_save,db->io_addr);//重新允許所有中斷spin_unlock_irqrestore(&db->lock,flags);returnIRQ_HANDLED;}

5.接收數據

static?void??

dm9000_rx(struct?net_device?*dev)??

{??

board_info_t?*db?=?netdev_priv(dev);??

struct?dm9000_rxhdr?rxhdr;??

struct?sk_buff?*skb;??

u8?rxbyte,?*rdptr;??

bool?GoodPacket;??

int?RxLen;??

/*?Check?packet?ready?or?not?*/??

do?{??

ior(db,?DM9000_MRCMDX);?/*?Dummy?read?*/??

//獲取接收數據的長度??

/*?Get?most?updated?data?*/??

rxbyte?=?readb(db->io_data);??

//檢查設備接收狀態??

/*?Status?check:?this?byte?must?be?0?or?1?*/??

if?(rxbyte?>?DM9000_PKT_RDY)?{??

dev_warn(db->dev,?"status?check?fail:?%d\n",?rxbyte);??

iow(db,?DM9000_RCR,?0x00);??/*?Stop?Device?*/??

iow(db,?DM9000_ISR,?IMR_PAR);???/*?Stop?INT?request?*/??

return;??

}??

if?(rxbyte?!=?DM9000_PKT_RDY)??

return;??

/*?A?packet?ready?now??&?Get?status/length?*/??

GoodPacket?=?true;??

writeb(DM9000_MRCMD,?db->io_addr);??

(db->inblk)(db->io_data,?&rxhdr,?sizeof(rxhdr));??

RxLen?=?le16_to_cpu(rxhdr.RxLen);??

if?(netif_msg_rx_status(db))??

dev_dbg(db->dev,?"RX:?status?%02x,?length?%04x\n",??

rxhdr.RxStatus,?RxLen);??

/*?Packet?Status?check?*/??

if?(RxLen?

GoodPacket?=?false;??

if?(netif_msg_rx_err(db))??

dev_dbg(db->dev,?"RX:?Bad?Packet?(runt)\n");??

}??

if?(RxLen?>?DM9000_PKT_MAX)?{??

dev_dbg(db->dev,?"RST:?RX?Len:%x\n",?RxLen);??

}??

/*?rxhdr.RxStatus?is?identical?to?RSR?register.?*/??

if?(rxhdr.RxStatus?&?(RSR_FOE?|?RSR_CE?|?RSR_AE?|??

RSR_PLE?|?RSR_RWTO?|??

RSR_LCS?|?RSR_RF))?{??

GoodPacket?=?false;??

if?(rxhdr.RxStatus?&?RSR_FOE)?{??

if?(netif_msg_rx_err(db))??

dev_dbg(db->dev,?"fifo?error\n");??

dev->stats.rx_fifo_errors++;??

}??

if?(rxhdr.RxStatus?&?RSR_CE)?{??

if?(netif_msg_rx_err(db))??

dev_dbg(db->dev,?"crc?error\n");??

dev->stats.rx_crc_errors++;??

}??

if?(rxhdr.RxStatus?&?RSR_RF)?{??

if?(netif_msg_rx_err(db))??

dev_dbg(db->dev,?"length?error\n");??

dev->stats.rx_length_errors++;??

}??

}??

/*?Move?data?from?DM9000?*/??

//如果接收正確，開始接收??

if?(GoodPacket??

&&?((skb?=?dev_alloc_skb(RxLen?+?4))?!=?NULL))?{??

skb_reserve(skb,?2);??

rdptr?=?(u8?*)?skb_put(skb,?RxLen?-?4);//獲取skb的數據指針??

/*?Read?received?packet?from?RX?SRAM?*/??

(db->inblk)(db->io_data,?rdptr,?RxLen);//讀取數據??

dev->stats.rx_bytes?+=?RxLen;??

/*?Pass?to?upper?layer?*/??

skb->protocol?=?eth_type_trans(skb,?dev);??

netif_rx(skb);//將接收到的skb交給協議層??

dev->stats.rx_packets++;??

}?else?{??

/*?need?to?dump?the?packet's?data?*/??

(db->dumpblk)(db->io_data,?RxLen);??

}??

}?while?(rxbyte?==?DM9000_PKT_RDY);??

}??

static voiddm9000_rx(struct net_device *dev){board_info_t *db = netdev_priv(dev);struct dm9000_rxhdr rxhdr;struct sk_buff *skb;u8 rxbyte, *rdptr;bool GoodPacket;int RxLen;/* Check packet ready or not */do {ior(db, DM9000_MRCMDX);/* Dummy read *///獲取接收數據的長度/* Get most updated data */rxbyte = readb(db->io_data);//檢查設備接收狀態/* Status check: this byte must be 0 or 1 */if (rxbyte > DM9000_PKT_RDY) {dev_warn(db->dev, "status check fail: %d\n", rxbyte);iow(db, DM9000_RCR, 0x00);/* Stop Device */iow(db, DM9000_ISR, IMR_PAR);/* Stop INT request */return;}if (rxbyte != DM9000_PKT_RDY)return;/* A packet ready now & Get status/length */GoodPacket = true;writeb(DM9000_MRCMD, db->io_addr);(db->inblk)(db->io_data, &rxhdr, sizeof(rxhdr));RxLen = le16_to_cpu(rxhdr.RxLen);if (netif_msg_rx_status(db))dev_dbg(db->dev, "RX: status %02x, length %04x\n",rxhdr.RxStatus, RxLen);/* Packet Status check */if (RxLen < 0x40) {GoodPacket = false;if (netif_msg_rx_err(db))dev_dbg(db->dev, "RX: Bad Packet (runt)\n");}if (RxLen > DM9000_PKT_MAX) {dev_dbg(db->dev, "RST: RX Len:%x\n", RxLen);}/* rxhdr.RxStatus is identical to RSR register. */if (rxhdr.RxStatus & (RSR_FOE | RSR_CE | RSR_AE |RSR_PLE | RSR_RWTO |RSR_LCS | RSR_RF)) {GoodPacket = false;if (rxhdr.RxStatus & RSR_FOE) {if (netif_msg_rx_err(db))dev_dbg(db->dev, "fifo error\n");dev->stats.rx_fifo_errors++;}if (rxhdr.RxStatus & RSR_CE) {if (netif_msg_rx_err(db))dev_dbg(db->dev, "crc error\n");dev->stats.rx_crc_errors++;}if (rxhdr.RxStatus & RSR_RF) {if (netif_msg_rx_err(db))dev_dbg(db->dev, "length error\n");dev->stats.rx_length_errors++;}}/* Move data from DM9000 *///如果接收正確，開始接收if (GoodPacket&& ((skb = dev_alloc_skb(RxLen + 4)) != NULL)) {skb_reserve(skb, 2);rdptr = (u8 *) skb_put(skb, RxLen - 4);//獲取skb的數據指針/* Read received packet from RX SRAM */(db->inblk)(db->io_data, rdptr, RxLen);//讀取數據dev->stats.rx_bytes += RxLen;/* Pass to upper layer */skb->protocol = eth_type_trans(skb, dev);netif_rx(skb);//將接收到的skb交給協議層dev->stats.rx_packets++;} else {/* need to dump the packet's data */(db->dumpblk)(db->io_data, RxLen);}} while (rxbyte == DM9000_PKT_RDY);}

6.發送完成

static?void?dm9000_tx_done(struct?net_device?*dev,?board_info_t?*db)??

{??

int?tx_status?=?ior(db,?DM9000_NSR);????/*?Got?TX?status?*/??

if?(tx_status?&?(NSR_TX2END?|?NSR_TX1END))?{??

/*?One?packet?sent?complete?*/??

//將數據包計數減1??

db->tx_pkt_cnt--;??

dev->stats.tx_packets++;??

if?(netif_msg_tx_done(db))??

dev_dbg(db->dev,?"tx?done,?NSR?%02x\n",?tx_status);??

/*?Queue?packet?check?&?send?*/??

//如果數據包數量依然大于0，說明是TX?RAM中的第二個包，再次啟動發送，將TX?RAM中第二個包發送出去??

if?(db->tx_pkt_cnt?>?0)?{??

/*把數據的長度填到TXPLL(發送包長度低字節)和TXPLH(發送包長度高字節)中*/????

iow(db,?DM9000_TXPLL,?skb->len);????

iow(db,?DM9000_TXPLH,?skb->len?>>?8);????

/*置發送控制寄存器(TX?Control?Register)的發送請求位TXREQ(Auto?clears?after?sending?completely)，這樣就可以發送出去了*/???

dev->trans_start?=?jiffies;??

}??

netif_wake_queue(dev);//喚醒發送隊列??

}??

}??

static void dm9000_tx_done(struct net_device *dev, board_info_t *db){int tx_status = ior(db, DM9000_NSR);/* Got TX status */if (tx_status & (NSR_TX2END | NSR_TX1END)) {/* One packet sent complete *///將數據包計數減1db->tx_pkt_cnt--;dev->stats.tx_packets++;if (netif_msg_tx_done(db))dev_dbg(db->dev, "tx done, NSR %02x\n", tx_status);/* Queue packet check & send *///如果數據包數量依然大于0，說明是TX RAM中的第二個包，再次啟動發送，將TX RAM中第二個包發送出去if (db->tx_pkt_cnt > 0) {/*把數據的長度填到TXPLL(發送包長度低字節)和TXPLH(發送包長度高字節)中*/iow(db, DM9000_TXPLL, skb->len);iow(db, DM9000_TXPLH, skb->len >> 8);/*置發送控制寄存器(TX Control Register)的發送請求位TXREQ(Auto clears after sending completely)，這樣就可以發送出去了*/dev->trans_start = jiffies;}netif_wake_queue(dev);//喚醒發送隊列}}

7.超時處理

static?void?dm9000_timeout(struct?net_device?*dev)??

{??

board_info_t?*db?=?netdev_priv(dev);??

u8?reg_save;??

unsigned?long?flags;??

/*?Save?previous?register?address?*/??

reg_save?=?readb(db->io_addr);??

spin_lock_irqsave(&db->lock,?flags);??

//停止發送隊列并復位DM9000網卡??

netif_stop_queue(dev);??

dm9000_reset(db);??

dm9000_init_dm9000(dev);??

/*?We?can?accept?TX?packets?again?*/??

//重新發送??

dev->trans_start?=?jiffies;??

netif_wake_queue(dev);??

/*?Restore?previous?register?address?*/??

writeb(reg_save,?db->io_addr);??

spin_unlock_irqrestore(&db->lock,?flags);??

}??

static void dm9000_timeout(struct net_device *dev){board_info_t *db = netdev_priv(dev);u8 reg_save;unsigned long flags;/* Save previous register address */reg_save = readb(db->io_addr);spin_lock_irqsave(&db->lock, flags);//停止發送隊列并復位DM9000網卡netif_stop_queue(dev);dm9000_reset(db);dm9000_init_dm9000(dev);/* We can accept TX packets again *///重新發送dev->trans_start = jiffies;netif_wake_queue(dev);/* Restore previous register address */writeb(reg_save, db->io_addr);spin_unlock_irqrestore(&db->lock, flags);} ?