platform_set_drvdata 和 platform_get_drvdata

原文地址：http://blog.chinaunix.net/uid-25932176-id-3063323.html

ndev是我们在probe函数中定义的局部变量，如果我想在其他地方使用它怎么办呢？ 这就需要把它保存起来。内核提供了这个方法，使用函数platform_set_drvdata()可以将ndev保存成平台总线设备的私有数据。以后再要使用它时只需调用platform_get_drvdata()就可以了。

 

 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;
     const unsigned char *mac_src;
     int ret = 0;
     int iosize;
     int i;
     u32 id_val;

     /* Init network device */
         /*使用alloc_etherdev()来生成一个net_device结构体，并对其公有成员赋值*/
     ndev = alloc_etherdev(sizeof(struct board_info));
     if (!ndev) {
         dev_err(&pdev->dev, "could not allocate device./n");
         return -ENOMEM;
     }

     SET_NETDEV_DEV(ndev, &pdev->dev);

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

     /* setup board info structure */
     db = netdev_priv(ndev);
     memset(db, 0, sizeof(*db));

     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;
     }

     iosize = res_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 = res_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;
     }

     /* fill in parameters for net-dev structure */
     ndev->base_addr = (unsigned long)db->io_addr;
     ndev->irq    = db->irq_res->start;

     /* 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 */
     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);

     /* 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;
     }

     /* 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] = ior(db, i+DM9000_PAR);
     }

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

     //platform_set_drvdata()可以将ndev保存成平台总线设备的私有数据。以后再要使用它时只需调用platform_get_drvdata()就可以了
     platform_set_drvdata(pdev, ndev);
     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;

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

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

     return ret;
 }