dm9000a驱动源码分析（二）

现在我们来看dm9000a的open函数：

/* *  Open the interface. *  The interface is opened whenever "ifconfig" actives it. 当使用ifconfig激活该网络接口时调用 */static intdm9000_open(struct net_device *dev){board_info_t *db = dev->priv;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;/*申请中断资源，注册中断函数*/if (request_irq(dev->irq, &dm9000_interrupt, irqflags, dev->name, dev))return -EAGAIN;/*复位DM9000芯片*/dm9000_reset(db);/*初始化DM9000的寄存器*/dm9000_init_dm9000(dev);/* Init driver variable */db->dbug_cnt = 0;/*检查链路载波状况*/mii_check_media(&db->mii, netif_msg_link(db), 1);/*启动发送队列*/netif_start_queue(dev);/*之前在probe函数中调用 INIT_DELAYED_WORK初始化了工作队列，并关联了一个操作函数dm9000_poll_work()，此时运行dm9000_schedule_poll来调用这个函数*/ dm9000_schedule_poll(db);return 0;}

static voiddm9000_reset(board_info_t * db){dev_dbg(db->dev, "resetting device\n");/* RESET device *//*指定DM9000当前的命令寄存器是NCR*/writeb(DM9000_NCR, db->io_addr);udelay(200);/*向NCR寄存器写入复位标志，芯片复位*/writeb(NCR_RST, db->io_data);udelay(200);}

/* * Initilize dm9000 board 配置DM9000芯片内部寄存器，使其能工作 */static voiddm9000_init_dm9000(struct net_device *dev){board_info_t *db = dev->priv;unsigned int imr;dm9000_dbg(db, 1, "entering %s\n", __func__);/* I/O mode 检查当前芯片的总线带宽8bit，16bit，32bit 芯片的总线带宽由硬件走线决定*/db->io_mode = ior(db, DM9000_ISR) >> 6;/* ISR bit7:6 keeps I/O mode *//* GPIO0 on pre-activate PHY 启动PHY*/iow(db, DM9000_GPR, 0);/* REG_1F bit0 activate phyxcer */iow(db, DM9000_GPCR, GPCR_GEP_CNTL);/* Let GPIO0 output */iow(db, DM9000_GPR, 0);/* Enable PHY */if (db->flags & DM9000_PLATF_EXT_PHY)iow(db, DM9000_NCR, NCR_EXT_PHY);/* Program operating register *//*清除发送配置选项*/iow(db, DM9000_TCR, 0);        /* TX Polling clear */iow(db, DM9000_BPTR, 0x3f);/* Less 3Kb, 200us */iow(db, DM9000_FCR, 0xff);/* Flow Control */iow(db, DM9000_SMCR, 0);        /* Special Mode *//* clear TX status *//*清除发送标志位*/iow(db, DM9000_NSR, NSR_WAKEST | NSR_TX2END | NSR_TX1END);/*清除中断标志位*/iow(db, DM9000_ISR, ISR_CLR_STATUS); /* Clear interrupt status *//* Set address filter table */dm9000_hash_table(dev);imr = IMR_PAR | IMR_PTM | IMR_PRM;if (db->type != TYPE_DM9000E)imr |= IMR_LNKCHNG;db->imr_all = imr;/* Enable TX/RX interrupt mask 使用发送，接收中断。SRAM缓冲区指针自动回0*/iow(db, DM9000_IMR, imr);/* Init Driver variable */db->tx_pkt_cnt = 0;db->queue_pkt_len = 0;dev->trans_start = 0;}