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2014年(19)

我的朋友

分类: LINUX

2014-09-23 19:06:38

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二:从网卡驱动说起。

         intel 100M 网卡驱动为例简要概述数据包的接收与发送流程。代码见(drivers/net/e100.c

网卡是属于PCI设备,它的注册跟一般的PCI设备注册没什么两样。

static int __init e100_init_module(void)

{

         if(((1 << debug) - 1) & NETIF_MSG_DRV) {

                   printk(KERN_INFO PFX "%s, %s\n", DRV_DESCRIPTION, DRV_VERSION);

                   printk(KERN_INFO PFX "%s\n", DRV_COPYRIGHT);

         }

 

         //注册PCI

        return pci_module_init(&e100_driver);

}

其中e100_driver对应为网卡的pci_driver.

static struct pci_driver e100_driver = {

         //驱动对应的名字

         .name =         DRV_NAME,

         //匹配类型

         .id_table =     e100_id_table,

         //侦测函数

         .probe =        e100_probe,

         //移除函数,设备移除时将调用此函数

         .remove =       __devexit_p(e100_remove),

#ifdef CONFIG_PM

         .suspend =      e100_suspend,

         .resume =       e100_resume,

#endif

}

当总数探测到PCI设备符合e100_id_table中的参数时,将会调用e100_probe,开始设备的初始化

e100_probe中:

static int __devinit e100_probe(struct pci_dev *pdev,

         const struct pci_device_id *ent)

{

         struct net_device *netdev;

         struct nic *nic;

         int err;

 

         //分配net_device并为其赋值

         //alloc_etherdev为以太网接口的net_device分配函数。它是alloc_netdev的封装函数

         if(!(netdev = alloc_etherdev(sizeof(struct nic)))) {

                   if(((1 << debug) - 1) & NETIF_MSG_PROBE)

                            printk(KERN_ERR PFX "Etherdev alloc failed, abort.\n");

                   return -ENOMEM;

         }

        

         //netdev中的函数指针赋初值

         netdev->open = e100_open;

         netdev->stop = e100_close;

         netdev->hard_start_xmit = e100_xmit_frame;

         netdev->get_stats = e100_get_stats;

         netdev->set_multicast_list = e100_set_multicast_list;

         netdev->set_mac_address = e100_set_mac_address;

         netdev->change_mtu = e100_change_mtu;

         netdev->do_ioctl = e100_do_ioctl;

         //支持ethtool工具时有效

         SET_ETHTOOL_OPS(netdev, &e100_ethtool_ops);

         netdev->tx_timeout = e100_tx_timeout;

         netdev->watchdog_timeo = E100_WATCHDOG_PERIOD;

         //轮询函数

         netdev->poll = e100_poll;

         netdev->weight = E100_NAPI_WEIGHT;

#ifdef CONFIG_NET_POLL_CONTROLLER

         netdev->poll_controller = e100_netpoll;

#endif

 

         //获得net_device私有数据区,并对其赋值

         //私有数据大小是由alloc_etherdev()参数中指定的

         nic = netdev_priv(netdev);

         nic->netdev = netdev;

         nic->pdev = pdev;

         nic->msg_enable = (1 << debug) - 1;

         pci_set_drvdata(pdev, netdev);

 

         //启动网卡.为之后DMAI/O内存映射做准备

//它实际上是对PCI的控制寄存器赋值来实现的

         if((err = pci_enable_device(pdev))) {

                   DPRINTK(PROBE, ERR, "Cannot enable PCI device, aborting.\n");

                   goto err_out_free_dev;

         }

 

         //获取该资源相关联的标志

         //如果该设备存在I/O内存,则置IORESOURCE_MEM

         if(!(pci_resource_flags(pdev, 0) & IORESOURCE_MEM)) {

                   DPRINTK(PROBE, ERR, "Cannot find proper PCI device "

                            "base address, aborting.\n");

                   err = -ENODEV;

                   goto err_out_disable_pdev;

         }

 

         //PCI6个寄存器都会调用资源分配函数进行申请

         if((err = pci_request_regions(pdev, DRV_NAME))) {

                   DPRINTK(PROBE, ERR, "Cannot obtain PCI resources, aborting.\n");

                   goto err_out_disable_pdev;

         }

 

         //探制设备的DMA能力。如果设备支持DMApci_set_dma_mask返回0

         pci_set_master(pdev);

         if((err = pci_set_dma_mask(pdev, 0xFFFFFFFFULL))) {

                   DPRINTK(PROBE, ERR, "No usable DMA configuration, aborting.\n");

                   goto err_out_free_res;

         }

 

         SET_MODULE_OWNER(netdev);

         SET_NETDEV_DEV(netdev, &pdev->dev);

 

         //映射设备对应的I/O。以后对设备寄存器的操作可以直接转换为对内存的操作

         nic->csr = ioremap(pci_resource_start(pdev, 0), sizeof(struct csr));

         if(!nic->csr) {

                   DPRINTK(PROBE, ERR, "Cannot map device registers, aborting.\n");

                   err = -ENOMEM;

                   goto err_out_free_res;

         }

 

         if(ent->driver_data)

                   nic->flags |= ich;

         else

                   nic->flags &= ~ich;

 

         spin_lock_init(&nic->cb_lock);

         spin_lock_init(&nic->cmd_lock);

         //设置定时器。

         init_timer(&nic->watchdog);

         nic->watchdog.function = e100_watchdog;

         nic->watchdog.data = (unsigned long)nic;

         init_timer(&nic->blink_timer);

         nic->blink_timer.function = e100_blink_led;

         nic->blink_timer.data = (unsigned long)nic;

 

         //nic->mem建立线性DMA。只是在支持ethtool的时候才有用

if((err = e100_alloc(nic))) {

                   DPRINTK(PROBE, ERR, "Cannot alloc driver memory, aborting.\n");

                   goto err_out_iounmap;

         }

         //nic成员赋初值

         e100_get_defaults(nic);

         e100_hw_reset(nic);

         e100_phy_init(nic);

         //读取网卡的EEPROM。其中存放着网卡的MAC地址。

         //EEPROM是通过对I/O映射内存的操作实现的,即nic->csr

         if((err = e100_eeprom_load(nic)))

                   goto err_out_free;

         //设置netdev->dev_addr

         memcpy(netdev->dev_addr, nic->eeprom, ETH_ALEN);

         if(!is_valid_ether_addr(netdev->dev_addr)) {

                   DPRINTK(PROBE, ERR, "Invalid MAC address from "

                            "EEPROM, aborting.\n");

                   err = -EAGAIN;

                   goto err_out_free;

         }

 

         /* Wol magic packet can be enabled from eeprom */

         if((nic->mac >= mac_82558_D101_A4) &&

            (nic->eeprom[eeprom_id] & eeprom_id_wol))

                   nic->flags |= wol_magic;

 

         pci_enable_wake(pdev, 0, nic->flags & (wol_magic | e100_asf(nic)));

         //注册网络设备

         if((err = register_netdev(netdev))) {

                   DPRINTK(PROBE, ERR, "Cannot register net device, aborting.\n");

                   goto err_out_free;

         }

 

         DPRINTK(PROBE, INFO, "addr 0x%lx, irq %d, "

                   "MAC addr %02X:%02X:%02X:%02X:%02X:%02X\n",

                   pci_resource_start(pdev, 0), pdev->irq,

                   netdev->dev_addr[0], netdev->dev_addr[1], netdev->dev_addr[2],

                   netdev->dev_addr[3], netdev->dev_addr[4], netdev->dev_addr[5]);

 

         return 0;

 

err_out_free:

         e100_free(nic);

err_out_iounmap:

         iounmap(nic->csr);

err_out_free_res:

         pci_release_regions(pdev);

err_out_disable_pdev:

         pci_disable_device(pdev);

err_out_free_dev:

         pci_set_drvdata(pdev, NULL);

         free_netdev(netdev);

         return err;

}

 

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