DM9000驱动的了解一(dm9000_probe)

DM9000驱动的理解一(dm9000_probe)

//__devinit 内核优化宏，编译器通过这些宏把代码优化放到合适的内存空间，宏__devinit标志设备初始化代码 
static int __devinit
dm9000_probe(struct platform_device *pdev)
{
	//这个platform_data是在板级配置文件中设置的
	struct dm9000_plat_data *pdata = pdev->dev.platform_data;
	struct board_info *db;	/* Point a board information structure */
	//网络设备驱动中两个重要结构体之一，另一个大名鼎鼎的结构体是skbuff
	struct net_device *ndev;
	const unsigned char *mac_src;
	int ret = 0;
	int iosize;
	int i;
	u32 id_val;

	/* Init network device */
	//初始化网络设备结构体net_device，最终是调用了函数alloc_netdev_mq，有时间我想好好分析下这个函数
	ndev = alloc_etherdev(sizeof(struct board_info));
	if (!ndev) 
	{
		//实际上就是printk啦,我忍不住想说linux的一大特点，就是喜欢用满天飞的define给别人起新名字
		dev_err(&pdev->dev, "could not allocate device.\n");
		return -ENOMEM;
	}

	SET_NETDEV_DEV(ndev, &pdev->dev);

	//最后还是printk。。。
	dev_dbg(&pdev->dev, "dm9000_probe()\n");

	/* setup board info structure */
	//让结构体指针指向结构体ndev内的的某个xx(xx还没搞懂是哪个变量或者结构体)
	db = netdev_priv(ndev);

	db->dev = &pdev->dev;
	db->ndev = ndev;
    //初始化自旋锁
	spin_lock_init(&db->lock);
	//初始化互斥锁
	mutex_init(&db->addr_lock);
	
	INIT_DELAYED_WORK(&db->phy_poll, dm9000_poll_work);

	//调用platform_get_resource获取资源填充结构体db,这个resource就是在板级配置
	//文件中填充的那个struct resouce.
	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;
	}
	//继续填充结构体db中....,获取一个设备irq，这个irq也是板级配置文件中设置的
	//我的板上的两个dm9000分别分配了190,191.
	db->irq_wake = platform_get_irq(pdev, 1);
	if (db->irq_wake >= 0) {
		dev_dbg(db->dev, "wakeup irq %d\n", db->irq_wake);

		//注册中断函数dm9000_wol_interrupt，中断号为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;
			}
		}
	}
	//计算即将申请内存大小，这个大小是板级配置文件中struct resouce 中.end减去.tart再加1
	//为什么要再加1?
	iosize = resource_size(db->addr_res);
	//我原来的理解是申请该大小内存区域，这个理解有偏差。
	//该函数的任务是检查申请的资源是否可用，如果可用则申请成功，
	//并标志为已经使用，其他驱动想再申请该资源时就会失败?
	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;
	}
	//把db->addr_res->start开始，大小iosize，物理空间映射到虚拟地址空间
	//这段虚拟地址空间开始地址是db->io_addr
	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;
	}
	//以下这段程序操作与上类似，因为dm9000提供了地址和数据两个访问口，所以映射了两个。
	
	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;
	}

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

	//设置dm9000位宽，根据板级配置文件中struct platform_data设置而定
	//由此可见，linux内核移植很大一部分工作是驱动移植，是必须要在读懂驱动的前提上进行的
	
	/* 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 */
		//以下三个参数很少设置
		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
	//软件复位dm9000,实际上就是往dm9000寄存器NCR上写1
	dm9000_reset(db);
    //读dm9000id。如果读写时序正确，基本就能读到id.如果读id错误，
    //要么是时序错了，要么就是硬件存在问题，我就遇到过这个坑爹的问题，
    //如果硬件存在故障，这是驱动调试最痛苦痛苦的事情。
	/* 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 */
	//读dm9000寄存器CHIPR确定类型
	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] = 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(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;
}