linux网络设备驱动DM9000驱动分析（3）

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10、DM9000驱动中有两个中断函数，dm9000_interrupt和dm9000_wol_interrupt

（1）dm9000_interrupt：触发中断的时机发生在：

1）DM9000接收到一个包以后。

2）DM9000发送完了一个包以后

static irqreturn_t dm9000_interrupt(int irq, void *dev_id){struct net_device *dev = dev_id;board_info_t *db = netdev_priv(dev);int int_status;unsigned long flags;u8 reg_save;dm9000_dbg(db, 3, "entering %s\n", __func__);/* A real interrupt coming *//* holders of db->lock must always block IRQs *///获取自旋锁，关中断spin_lock_irqsave(&db->lock, flags);/* Save previous register address */reg_save = readb(db->io_addr);/* Disable all interrupts */iow(db, DM9000_IMR, IMR_PAR);/* Got DM9000 interrupt status */int_status = ior(db, DM9000_ISR);/* Got ISR */iow(db, DM9000_ISR, int_status);/* Clear ISR status */if (netif_msg_intr(db))dev_dbg(db->dev, "interrupt status %02x\n", int_status);/* Received the coming packet *///如果是接收中断，读取接收的数据并存入skbuff，并提交协议上一层 if (int_status & ISR_PRS)                 //PRS: packet receive latchdm9000_rx(dev);/* Trnasmit Interrupt check */ //由于发送完了数据而触发的发送中断，如果还有包未发完，继续发送。if (int_status & ISR_PTS)dm9000_tx_done(dev, db);//如果是DM9000E系列的芯片，作特别处理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 */iow(db, DM9000_IMR, db->imr_all);/* Restore previous register address */writeb(reg_save, db->io_addr);spin_unlock_irqrestore(&db->lock, flags);return IRQ_HANDLED;}

（2）dm9000_wol_interrupt : 这个中断函数主要做的事情是读dm9000寄存器NSR,WCR,根据读到的内容作出相应提示.

static irqreturn_t dm9000_wol_interrupt(int irq, void *dev_id){struct net_device *dev = dev_id;board_info_t *db = netdev_priv(dev);unsigned long flags;unsigned nsr, wcr; //关中断，获得自旋锁spin_lock_irqsave(&db->lock, flags);nsr = ior(db, DM9000_NSR);wcr = ior(db, DM9000_WCR);         //WCR :wake up control registerdev_dbg(db->dev, "%s: NSR=0x%02x, WCR=0x%02x\n", __func__, nsr, wcr);if (nsr & NSR_WAKEST) {              //WAKEST :wakeup event status/* clear, so we can avoid */iow(db, DM9000_NSR, NSR_WAKEST);if (wcr & WCR_LINKST)dev_info(db->dev, "wake by link status change\n");if (wcr & WCR_SAMPLEST)dev_info(db->dev, "wake by sample packet\n");if (wcr & WCR_MAGICST )dev_info(db->dev, "wake by magic packet\n");if (!(wcr & (WCR_LINKST | WCR_SAMPLEST | WCR_MAGICST)))dev_err(db->dev, "wake signalled with no reason? ""NSR=0x%02x, WSR=0x%02x\n", nsr, wcr);} //释放自旋锁，恢复本地中断 spin_unlock_irqrestore(&db->lock, flags);return (nsr & NSR_WAKEST) ? IRQ_HANDLED : IRQ_NONE;}

11、在中断中，如果还有包未发完，则会调用dm9000_tx_done。

该函数首先读取dm9000寄存器NSR（Network Status Register）获取发送的状态，存在变量tx_status中，如果发送状态为NSR_TX2END（第2个包发送完毕）或者NSR_TX1END（第1个包发送完毕），则将待发送的数据包数量（db->tx_pkt_cnt）减1，已发送的数据包数量（dev->stats.tx_packets）加1。

static void dm9000_tx_done(struct net_device *dev, board_info_t *db){int tx_status = ior(db, DM9000_NSR);/*  NSR: 网络状态寄存器，读取dm9000寄存器*/if (tx_status & (NSR_TX2END | NSR_TX1END)) {/* One packet sent complete */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 */if (db->tx_pkt_cnt > 0)                    //db->tx_pkt_cnt（待发送的数据包）dm9000_send_packet(dev, db->queue_ip_summed,   db->queue_pkt_len);netif_wake_queue(dev);                //通知内核可以将待发送的数据包进入发送队列}    }

11、超时函数 dm9000_timeout

发送数据失败时，系统会调用dm9000_timeout函数。当传输数据超时时，意味发送操作失败或硬件进入未知状态。在超时函数中会调用netif_wake_queue()函数来重新启动设备发送队列。主要的功能是保存寄存器地址，停止队列，重启并初始化DM9000，唤醒队列，恢复寄存器地址。

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 */spin_lock_irqsave(&db->lock, flags);reg_save = readb(db->io_addr);         //保存寄存器地址netif_stop_queue(dev);                      //停止队列dm9000_reset(db);                            //复位dm9000_init_dm9000(dev);             //初始化/* We can accept TX packets again */dev->trans_start = jiffies; /* prevent tx timeout 记录最后的数据包开始发送的时间戳*/netif_wake_queue(dev);                //重启发送队列/* Restore previous register address */writeb(reg_save, db->io_addr);            //恢复寄存器地址spin_unlock_irqrestore(&db->lock, flags);}

13、设置多播地址dm9000_hash_table。

static void dm9000_hash_table(struct net_device *dev){board_info_t *db = netdev_priv(dev);unsigned long flags;spin_lock_irqsave(&db->lock, flags); //设置自旋锁，同时保存中断设置dm9000_hash_table_unlocked(dev); //调用dm9000_hash_table_unlocked来进行设置spin_unlock_irqrestore(&db->lock, flags);//解锁}

dm9000_hash_table_unlocked：

static void dm9000_hash_table_unlocked(struct net_device *dev){board_info_t *db = netdev_priv(dev);struct netdev_hw_addr *ha;int i, oft;u32 hash_val;u16 hash_table[4];u8 rcr = RCR_DIS_LONG | RCR_DIS_CRC | RCR_RXEN; //RCR :接收控制寄存器//DIS_LONG:discard long packet,超出1522字节. DIS_CRC:discard crc error packet.  RXEN:RX enabledm9000_dbg(db, 1, "entering %s\n", __func__);for (i = 0, oft = DM9000_PAR; i < 6; i++, oft++)        //PAR:物理地址寄存器iow(db, oft, dev->dev_addr[i]);        //将物理地址写入PAR寄存器  PAB 0-5/* Clear Hash Table */for (i = 0; i < 4; i++)hash_table[i] = 0x0;/* broadcast address */hash_table[3] = 0x8000;//IFF : interface flags if (dev->flags & IFF_PROMISC)     //  IFF_PROMISC:    receive all packetsrcr |= RCR_PRMSC;              //PRMSC : promiscuous mode  混杂模式if (dev->flags & IFF_ALLMULTI)    //  IFF_ALLMULTI : receive all multicast packetsrcr |= RCR_ALL;                  //ALL : pass all multicast/* the multicast address in Hash Table : 64 bits */netdev_for_each_mc_addr(ha, dev) {              //遍历链表hash_val = ether_crc_le(6, ha->addr) & 0x3f;hash_table[hash_val / 16] |= (u16) 1 << (hash_val % 16);}/* Write the hash table to MAC MD table */for (i = 0, oft = DM9000_MAR; i < 4; i++) {            //给MAR寄存器写值 MAR : multicast address registeriow(db, oft++, hash_table[i]);iow(db, oft++, hash_table[i] >> 8);}iow(db, DM9000_RCR, rcr);                //设置RCR接收控制寄存器}