ARM-Linux驱动--DM9000网卡驱动分析（二）

 

下面开始分析具体的代码，这里由于使DM9000驱动更容易理解，在不影响基本的功能的前提下，这里将尽可能的简化该驱动（如：去掉该驱动中支持电源管理的功能）

分析该驱动

1、首先看一下该驱动的平台设备驱动的结构体定义

/*平台设备驱动的结构体定义
*在该结构体中可以定义有关Power Management的管理函数
*该驱动中将其省略，侧重分析dm9000的基本原理
*/
static struct platform_driver dm9000_driver = {
    .driver = {
        .name    = "dm9000",/* 该名称和系统初始化中，平台设备的名称一致 */
        .owner   = THIS_MODULE,
    },
    .probe   = dm9000_probe,/* 资源探测函数 */
    .remove  = __devexit_p(dm9000_drv_remove),/* 设备移除函数 */
};

在执行insmod后内核自动那个执行下面的函数

static int __init
dm9000_init(void)
{
    printk(KERN_INFO "%s Ethernet Driver, V%s\n", CARDNAME, DRV_VERSION);

    return platform_driver_register(&dm9000_driver);
}

调用函数platform_driver_register()函数注册驱动。

3、自动执行驱动的probe函数，进行资源的探测和申请资源。

其中BWSCON为总线宽度 等待控制寄存器

其中第[19:18]位的作用如下

下面函数中将两位设置为11，也就是WAIT使能，bank4使用UB/LB。

alloc_etherdev()函数分配一个网络设备的结构体，原型在include/linux/etherdevice.h

原型如下：

extern struct net_device *alloc_etherdev_mq(int sizeof_priv, unsigned int queue_count);
#define alloc_etherdev(sizeof_priv) alloc_etherdev_mq(sizeof_priv, 1)

该函数中需要将获得的资源信息存储在一个结构体中，定义如下：

/* Structure/enum declaration ------------------------------- */
typedef struct board_info {

    void __iomem    *io_addr;   /* Register I/O base address */
    void __iomem    *io_data;   /* Data I/O address */
    u16      irq;       /* IRQ */

    u16     tx_pkt_cnt;
    u16     queue_pkt_len;
    u16     queue_start_addr;
    u16     queue_ip_summed;
    u16     dbug_cnt;
    u8      io_mode;        /* 0:word, 2:byte */
    u8      phy_addr;
    u8      imr_all;

    unsigned int    flags;
    unsigned int    in_suspend :1;
    unsigned int    wake_supported :1;
    int     debug_level;

    enum dm9000_type type;

    void (*inblk)(void __iomem *port, void *data, int length);
    void (*outblk)(void __iomem *port, void *data, int length);
    void (*dumpblk)(void __iomem *port, int length);

    struct device   *dev;        /* parent device */

    struct resource *addr_res;   /* resources found */
    struct resource *data_res;
    struct resource *addr_req;   /* resources requested */
    struct resource *data_req;
    struct resource *irq_res;

    int      irq_wake;

    struct mutex     addr_lock; /* phy and eeprom access lock */

    struct delayed_work phy_poll;
    struct net_device  *ndev;

    spinlock_t  lock;

    struct mii_if_info mii;
    u32     msg_enable;
    u32     wake_state;

    int     rx_csum;
    int     can_csum;
    int     ip_summed;
} board_info_t;

下面是probe函数，

其中有个函数db = netdev_priv(ndev)

该函数实际上是返回网卡私有成员的数据结构地址

函数如下，定义在include/linux/net_device.h中

static inline void *netdev_priv(const struct net_device *dev)
{
    return (char *)dev + ALIGN(sizeof(struct net_device), NETDEV_ALIGN);
}

/*
 * Search DM9000 board, allocate space and register it
 */
static int __devinit
dm9000_probe(struct platform_device *pdev)
{
    struct dm9000_plat_data *pdata = pdev->dev.platform_data;
    struct board_info *db;  /* Point a board information structure */
    struct net_device *ndev;/* 网络设备 */
    const unsigned char *mac_src;
    int ret = 0;
    int iosize;
    int i;
    u32 id_val;

    unsigned char ne_def_eth_mac_addr[]={0x00,0x12,0x34,0x56,0x80,0x49};/* 设定默认的mac地址 */
    static void *bwscon;/* 保存ioremap返回的寄存器的虚拟地址，下同 */
    static void *gpfcon;
    static void *extint0;
    static void *intmsk;
    /*Added by yan*/
    #define BWSCON           (0x48000000)
    #define GPFCON           (0x56000050)
    #define EXTINT0           (0x56000088)
    #define INTMSK           (0x4A000008)

    bwscon=ioremap_nocache(BWSCON,0x0000004);
    gpfcon=ioremap_nocache(GPFCON,0x0000004);
    extint0=ioremap_nocache(EXTINT0,0x0000004);
    intmsk=ioremap_nocache(INTMSK,0x0000004);

    writel( readl(bwscon)|0xc0000,bwscon);/* 将BWSCON寄存器[19:18]设置为11 */
    writel( (readl(gpfcon) & ~(0x3 << 14)) | (0x2 << 14), gpfcon); /* 设置GPF寄存器 */
    writel( readl(gpfcon) | (0x1 << 7), gpfcon); // Disable pull-up，不使能上拉
    writel( (readl(extint0) & ~(0xf << 28)) | (0x4 << 28), extint0); //rising edge，设置上升沿触发中断
    writel( (readl(intmsk))  & ~0x80, intmsk);/* 设置中断屏蔽寄存器 */

    /*End of add*/
    /* Init network device */
    /* 使用alloc_etherdev()函数分配一个网络设备的结构体，原型在include/linux/etherdevice.h */
    ndev = alloc_etherdev(sizeof(struct board_info));
    if (!ndev) {
        dev_err(&pdev->dev, "could not allocate device.\n");
        return -ENOMEM;
    }

/*通过SET_NETDEV_DEV(netdev, &pdev->dev)宏设置net_device.device->parent为当前的pci_device->device
*(这儿net_device包含的是device结构，而不是指针）。这样，就建立起了net_device到device的联系。
*/
    SET_NETDEV_DEV(ndev, &pdev->dev);

    dev_dbg(&pdev->dev, "dm9000_probe()\n");

    /* setup board info structure */
    /* 下面都是设置board_info结构体 */
    db = netdev_priv(ndev);/* 返回dev->priv的地址 */

    db->dev = &pdev->dev;
    db->ndev = ndev;

    spin_lock_init(&db->lock);
    mutex_init(&db->addr_lock);

    INIT_DELAYED_WORK(&db->phy_poll, dm9000_poll_work);

    db->addr_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    db->data_res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
    db->irq_res  = platform_get_resource(pdev, IORESOURCE_IRQ, 0);

    if (db->addr_res == NULL || db->data_res == NULL ||
        db->irq_res == NULL) {
        dev_err(db->dev, "insufficient resources\n");
        ret = -ENOENT;
        goto out;
    }

    db->irq_wake = platform_get_irq(pdev, 1);
    if (db->irq_wake >= 0) {
        dev_dbg(db->dev, "wakeup irq %d\n", db->irq_wake);

        ret = request_irq(db->irq_wake, dm9000_wol_interrupt,
                  IRQF_SHARED, dev_name(db->dev), ndev);
        if (ret) {
            dev_err(db->dev, "cannot get wakeup irq (%d)\n", ret);
        } else {

            /* test to see if irq is really wakeup capable */
            ret = set_irq_wake(db->irq_wake, 1);
            if (ret) {
                dev_err(db->dev, "irq %d cannot set wakeup (%d)\n",
                    db->irq_wake, ret);
                ret = 0;
            } else {
                set_irq_wake(db->irq_wake, 0);
                db->wake_supported = 1;
            }
        }
    }

    iosize = resource_size(db->addr_res);
    db->addr_req = request_mem_region(db->addr_res->start, iosize,
                      pdev->name);

    if (db->addr_req == NULL) {
        dev_err(db->dev, "cannot claim address reg area\n");
        ret = -EIO;
        goto out;
    }

    db->io_addr = ioremap(db->addr_res->start, iosize);

    if (db->io_addr == NULL) {
        dev_err(db->dev, "failed to ioremap address reg\n");
        ret = -EINVAL;
        goto out;
    }

    iosize = resource_size(db->data_res);
    db->data_req = request_mem_region(db->data_res->start, iosize,
                      pdev->name);

    if (db->data_req == NULL) {
        dev_err(db->dev, "cannot claim data reg area\n");
        ret = -EIO;
        goto out;
    }

    db->io_data = ioremap(db->data_res->start, iosize);

    if (db->io_data == NULL) {
        dev_err(db->dev, "failed to ioremap data reg\n");
        ret = -EINVAL;
        goto out;
    }
    /* 设置结构体board_info结束 */

    /* fill in parameters for net-dev structure */
    ndev->base_addr = (unsigned long)db->io_addr;/* 设置网络设备的地址 */
    ndev->irq    = db->irq_res->start;/* 设置网络设备的中断资源地址 */

    /* ensure at least we have a default set of IO routines */
    dm9000_set_io(db, iosize);

    /* check to see if anything is being over-ridden */

    /*根据pdev->dev.platform_data的信息判断IO的宽度并设置相应的宽度*/
    if (pdata != NULL) {
        /* check to see if the driver wants to over-ride the
         * default IO width */

        if (pdata->flags & DM9000_PLATF_8BITONLY)
            dm9000_set_io(db, 1);

        if (pdata->flags & DM9000_PLATF_16BITONLY)
            dm9000_set_io(db, 2);

        if (pdata->flags & DM9000_PLATF_32BITONLY)
            dm9000_set_io(db, 4);

        /* check to see if there are any IO routine
         * over-rides */

        if (pdata->inblk != NULL)
            db->inblk = pdata->inblk;

        if (pdata->outblk != NULL)
            db->outblk = pdata->outblk;

        if (pdata->dumpblk != NULL)
            db->dumpblk = pdata->dumpblk;

        db->flags = pdata->flags;
    }

#ifdef CONFIG_DM9000_FORCE_SIMPLE_PHY_POLL
    db->flags |= DM9000_PLATF_SIMPLE_PHY;
#endif

    dm9000_reset(db);/* 复位 */

    /* try multiple times, DM9000 sometimes gets the read wrong */
    for (i = 0; i < 8; i++) {
        id_val  = ior(db, DM9000_VIDL);
        id_val |= (u32)ior(db, DM9000_VIDH) << 8;
        id_val |= (u32)ior(db, DM9000_PIDL) << 16;
        id_val |= (u32)ior(db, DM9000_PIDH) << 24;

        if (id_val == DM9000_ID)
            break;
        dev_err(db->dev, "read wrong id 0x%08x\n", id_val);
    }

    if (id_val != DM9000_ID) {
        dev_err(db->dev, "wrong id: 0x%08x\n", id_val);
        ret = -ENODEV;
        goto out;
    }

    /* Identify what type of DM9000 we are working on */

    id_val = ior(db, DM9000_CHIPR);
    dev_dbg(db->dev, "dm9000 revision 0x%02x\n", id_val);

    switch (id_val) {
    case CHIPR_DM9000A:
        db->type = TYPE_DM9000A;
        break;
    case CHIPR_DM9000B:
        db->type = TYPE_DM9000B;
        break;
    default:
        dev_dbg(db->dev, "ID %02x => defaulting to DM9000E\n", id_val);
        db->type = TYPE_DM9000E;
    }

    /* dm9000a/b are capable of hardware checksum offload */
    if (db->type == TYPE_DM9000A || db->type == TYPE_DM9000B) {
        db->can_csum = 1;
        db->rx_csum = 1;
        ndev->features |= NETIF_F_IP_CSUM;
    }

    /* from this point we assume that we have found a DM9000 */

    /* driver system function */
    ether_setup(ndev);

    ndev->netdev_ops = &dm9000_netdev_ops;
    ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
    ndev->ethtool_ops    = &dm9000_ethtool_ops;

    db->msg_enable       = NETIF_MSG_LINK;
    db->mii.phy_id_mask  = 0x1f;
    db->mii.reg_num_mask = 0x1f;
    db->mii.force_media  = 0;
    db->mii.full_duplex  = 0;
    db->mii.dev       = ndev;
    db->mii.mdio_read    = dm9000_phy_read;
    db->mii.mdio_write   = dm9000_phy_write;

    mac_src = "eeprom";

    /* try reading the node address from the attached EEPROM */
    for (i = 0; i < 6; i += 2)
        dm9000_read_eeprom(db, i / 2, ndev->dev_addr+i);

    if (!is_valid_ether_addr(ndev->dev_addr) && pdata != NULL) {
        mac_src = "platform data";
        memcpy(ndev->dev_addr, pdata->dev_addr, 6);
    }

    if (!is_valid_ether_addr(ndev->dev_addr)) {
        /* try reading from mac */

        mac_src = "chip";
        for (i = 0; i < 6; i++)
            ndev->dev_addr[i] = ne_def_eth_mac_addr[i];
    }

    if (!is_valid_ether_addr(ndev->dev_addr))
        dev_warn(db->dev, "%s: Invalid ethernet MAC address. Please "
             "set using ifconfig\n", ndev->name);

    /* 设置pdev->dev->driver_data为ndev，保存成平台设备总线上的数据，以后使用只需platform_get_drvdata()即可*/
    platform_set_drvdata(pdev, ndev);

    /* 注册该网络设备 */
    ret = register_netdev(ndev);

    if (ret == 0)
        printk(KERN_INFO "%s: dm9000%c at %p,%p IRQ %d MAC: %pM (%s)\n",
               ndev->name, dm9000_type_to_char(db->type),
               db->io_addr, db->io_data, ndev->irq,
               ndev->dev_addr, mac_src);
    return 0;

/* 异常处理 */
out:
    dev_err(db->dev, "not found (%d).\n", ret);

    dm9000_release_board(pdev, db);
    free_netdev(ndev);

    return ret;
}

这样，最后完成了网络设备的数据保存到总线上，将网络设备注册到内核。

4、设备的移除函数

/* 该函数是将设备从内核中移除，释放资源，在移除设备驱动时执行 */
static int __devexit
dm9000_drv_remove(struct platform_device *pdev)
{
    struct net_device *ndev = platform_get_drvdata(pdev);/* 从总线获取probe函数保存到总线的设备信息 */

    platform_set_drvdata(pdev, NULL);/* 释放pdev资源 */

    unregister_netdev(ndev);/* 解除网络设备 */
    dm9000_release_board(pdev, (board_info_t *) netdev_priv(ndev));/* 释放该设备申请的IO资源 */
    free_netdev(ndev);      /* free device structure */

    dev_dbg(&pdev->dev, "released and freed device\n");
    return 0;
}