LAN9221网卡驱动之三 接收/发送完成中断

网卡中断主要是在接收新数据和数据发送完成时被调用，提醒网络驱动设备接收新数据和唤醒发送队列。

static irqreturn_t smsc911x_irqhandler(int irq, void *dev_id)
{
	struct net_device *dev = dev_id;
	struct smsc911x_data *pdata = netdev_priv(dev);
	u32 intsts = smsc911x_reg_read(pdata, INT_STS);
	u32 inten = smsc911x_reg_read(pdata, INT_EN);
	int serviced = IRQ_NONE;
	u32 temp;

	if (unlikely(intsts & inten & INT_STS_SW_INT_)) {/*判断软中断有没有触发，如果有则关掉软中断并将其清零*/
		temp = smsc911x_reg_read(pdata, INT_EN);
		temp &= (~INT_EN_SW_INT_EN_);
		smsc911x_reg_write(pdata, INT_EN, temp);/*关中断*/
		smsc911x_reg_write(pdata, INT_STS, INT_STS_SW_INT_);/*清零中断*/
		pdata->software_irq_signal = 1;
		smp_wmb();
		serviced = IRQ_HANDLED;
	}

	if (unlikely(intsts & inten & INT_STS_RXSTOP_INT_)) {
		/* Called when there is a multicast update scheduled and
		 * it is now safe to complete the update */
		SMSC_TRACE(INTR, "RX Stop interrupt");
		smsc911x_reg_write(pdata, INT_STS, INT_STS_RXSTOP_INT_);
		if (pdata->multicast_update_pending)
			smsc911x_rx_multicast_update_workaround(pdata);
		serviced = IRQ_HANDLED;
	}

	if (intsts & inten & INT_STS_TDFA_) {/*发数据完成，唤醒发送队列*/
		temp = smsc911x_reg_read(pdata, FIFO_INT);
		temp |= FIFO_INT_TX_AVAIL_LEVEL_;
		smsc911x_reg_write(pdata, FIFO_INT, temp);
		smsc911x_reg_write(pdata, INT_STS, INT_STS_TDFA_);
		netif_wake_queue(dev);
		serviced = IRQ_HANDLED;
	}

	if (unlikely(intsts & inten & INT_STS_RXE_)) {
		SMSC_TRACE(INTR, "RX Error interrupt");
		smsc911x_reg_write(pdata, INT_STS, INT_STS_RXE_);
		serviced = IRQ_HANDLED;
	}

	if (likely(intsts & inten & INT_STS_RSFL_)) {/*收到新的网卡数据触发中断*/
		if (likely(napi_schedule_prep(&pdata->napi))) {
			/* Disable Rx interrupts */
			temp = smsc911x_reg_read(pdata, INT_EN);
			temp &= (~INT_EN_RSFL_EN_);
			smsc911x_reg_write(pdata, INT_EN, temp);
			/* Schedule a NAPI poll */
			__napi_schedule(&pdata->napi);
		} else {
			SMSC_WARNING(RX_ERR,
				"napi_schedule_prep failed");
		}
		serviced = IRQ_HANDLED;
	}

	return serviced;
}