2410平台上dm9000a网卡驱动分析

关于该函数的说明：

/**
 * alloc_netdev_mq - allocate network device
 * @sizeof_priv: size of private data to allocate space for
 * @name:  device name format string
 * @setup:  callback to initialize device
 * @queue_count: the number of subqueues to allocate
 *
 * Allocates a struct net_device with private data area for driver use
 * and performs basic initialization.  Also allocates subquue structs
 * for each queue on the device at the end of the netdevice.
 */

可见，alloc_etherdev为设备驱动分配了私有数据空间，并对设备驱动做了一些初始化工作。

 

接下来，设备驱动将要检查设备的resources的数量，如果数量小于2或者大于3，则初始化函数自动返回，初始化失败。我们的设备驱动中，resources的数量为2：一个表示设备的IO地址，另一个是设备

的中断号。

 

代码

        base = pdev->resource[0].start;
        ndev->irq = pdev->resource[1].start;
 

分别得到设备的端口地址和中断号。

接下来，驱动程序将向系统申请io内存，从地址base开始，大小为4个字节。如果申请成功，接下来需要做的就是将地址重新映射，从地址base开始，长度为4个字节。这样做的原因主要是驱动程序一般

不直接访问物理地址，而访问虚拟地址。地址重新映射成功后，就调用dm9k_probe函数进行设备初始化。

dm9k_probe函数的全部代码如下

int __init dm9k_probe(struct net_device *dev, unsigned long addr)
{
        struct board_info *db; /* Point a board information structure */
        u32 id_val;
        u16 i, j;
        int retval;
          /* Search for DM9000 serial NIC */
        PUTB(DM9KS_VID_L, addr);
        id_val = GETB(addr + 2); /* Change offset to 2 ^^^^^ */
        PUTB(DM9KS_VID_H, addr);
        id_val |= GETB(addr + 2) << 8;
        PUTB(DM9KS_PID_L, addr);
        id_val |= GETB(addr + 2) << 16;
        PUTB(DM9KS_PID_H, addr);
        id_val |= GETB(addr + 2) << 24;
        if (id_val != DM9KS_ID && id_val != DM9010_ID) {
                /* Dm9k chip not found */
                printk("dmfe_probe(): DM9000 not found. ID=%08X\n", id_val);
                return -ENODEV;
                }
               
        printk("<DM9KS> I/O: %lx, VID: %x \n",addr, id_val);
        /* Allocated board information structure */
        memset(dev->priv, 0, sizeof(struct board_info));
        db = (board_info_t *)dev->priv;
        dmfe_dev = dev;
        db->io_addr = addr;
        db->io_data = addr + 2; /* Change offset to 2 ^^^^^ */
        /* driver system function */
                               
        dev->base_addr = addr;
        dev->irq = IRQ_EINT2;
        dev->open = &dmfe_open;
        dev->hard_start_xmit = &dmfe_start_xmit;
        dev->watchdog_timeo = HZ;
        dev->tx_timeout = dmfe_timeout;
        dev->stop = &dmfe_stop;
        dev->get_stats = &dmfe_get_stats;
        dev->set_multicast_list = &dm9000_hash_table;
        dev->do_ioctl = &dmfe_do_ioctl;
        for(i=0,j=0x10; i<6; i++,j++)
          {
                db->srom[i] = ior(db, j);
              
          }
      
        /* Set Node Address */
        for (i=0; i<6; i++)
                dev->dev_addr[i] = db->srom[i];
        retval = register_netdev(dev);
        if (retval == 0) {
                /* now, print out the card info, in a short format.. */
                printk("%s: at %#lx IRQ %d\n",
                        dev->name, dev->base_addr, dev->irq);
                if (dev->dma != (unsigned char)-1)
                        printk(" DMA %d\n", dev->dma);
                if (!is_valid_ether_addr(dev->dev_addr)) {
                        printk("%s: Invalid ethernet MAC address. Please "
                               "set using ifconfig\n", dev->name);
                } else {
                        /* Print the Ethernet address */
                        printk("%s: Ethernet addr: ", dev->name);
                        for (i = 0; i < 5; i++)
                                printk("%2.2x:", dev->dev_addr[i]);
                        printk("%2.2x\n", dev->dev_addr[5]);
                }
        }
        return 0;
}
 

函数首先调用PUTB来写dm9000a芯片，来看看PUTB的实现

#define PUTB(d,a) *((volatile unsigned char *) (a)) = d
 

可见，PUTB是直接使用的指针，而没有使用内核提供的write等函数，同样，GETB函数如下

#define GETB(a) *((volatile unsigned char *) (a))
 

注意，这里的地址都是虚拟地址，因为前面调用函数dm9k_probe时传递的addr时重新映射后的，而不是直接传送的物理地址。