dm9000a框架原理图:
EEPROM Interface接口用于存放mac地址，InternalSRAM用于存放收发数据，MII部分把MAC部分与PHY部分连接起来通信，AUTO-MDIX用于自适应10/100M网络,在物理层上,MAC在PHY之下。
由dm9000a驱动可知，dm9000a驱动是用platform模型编写的，分析一个驱动源码都是从模块加载函数module_init()开始，而dm9000a加载函数是module_init(dm9000_init).
继而调用：
static int __init
dm9000_init(void)
{
printk(KERN_INFO "%s Ethernet Driver, V%s\n", CARDNAME, DRV_VERSION);
return platform_driver_register(&dm9000_driver);
}
dm9000_driver结构体：
static struct platform_driver dm9000_driver = {
.driver = {
.name = "dm9000",//名字
.owner = THIS_MODULE,
},
.probe = dm9000_probe,//模块加载后，调用probe函数
.remove = __devexit_p(dm9000_drv_remove),
.suspend = dm9000_drv_suspend,
.resume = dm9000_drv_resume,
};
模块加载之后，调用probe函数，如下：
/*
* 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;
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};
/* ------------------------------------------------------------------------ */
static void *bwscon;
static void *gpfcon;
static void *extint0;
static void *intmsk;
#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);
writel( (readl(gpfcon) & ~(0x3 << 14)) | (0x2 << 14), gpfcon);
writel( readl(gpfcon) | (0x1 << 7), gpfcon); // Disable pull-up
writel( (readl(extint0) & ~(0xf << 28)) | (0x4 << 28), extint0); //rising edge
writel( (readl(intmsk)) & ~0x80, intmsk);
/* ------------------------------------------------------------------------ */
/* Init network device */
/* 分配eth网卡资源，私有数据区保存board_info*/
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 初始化为0*/
db = ndev->priv;
memset(db, 0, sizeof(*db));
db->dev = &pdev->dev;
db->ndev = ndev;
/*初始化spinlock*/
spin_lock_init(&db->lock);
mutex_init(&db->addr_lock);
/*提交一个任务给一个工作队列，你需要填充一个work_struct结构db->phy_poll*/
INIT_DELAYED_WORK(&db->phy_poll, dm9000_poll_work);
/*获取IO内存和中断资源*/
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;
}
/*映射到内核，并获得IO内存的虚拟地址，ioremap完成页表的建立，
不同于vmalloc，但是，它实际上不分配内存*/
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 */
/*获得网络设备的基地址*/
ndev->base_addr = (unsigned long)db->io_addr;
/*获得网络设备的中断号*/
ndev->irq = db->irq_res->start;
/* ensure at least we have a default set of IO routines */
/*设置默认的IO函数*/
dm9000_set_io(db, iosize);
/*如果平台数据不为空 */
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
/*根据board info信息，复位DM9000芯片*/
dm9000_reset(db);
/*读取Vendor ID Register,Product ID Register中的值，与0x90000A46比较，如果相等，则说明是DM9000*/
/* 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);
}
/*芯片的ID获取失败，驱动不匹配*/
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 */
/*读取Chip Revision Register中的值*/
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 */
/*设置部分net_device字段*/
ether_setup(ndev);
ndev->open = &dm9000_open;
ndev->hard_start_xmit = &dm9000_start_xmit;
ndev->tx_timeout = &dm9000_timeout;
ndev->watchdog_timeo = msecs_to_jiffies(watchdog);
ndev->stop = &dm9000_stop;
ndev->set_multicast_list = &dm9000_hash_table;
/*对ethtool支持的相关声明可在<linux/ethtool.h>中找到。
它的核心是一个ethtool_ops类型的结构，里边包含一个全部
的24个不同的方法来支持ethtool*/
ndev->ethtool_ops = &dm9000_ethtool_ops;
ndev->do_ioctl = &dm9000_ioctl;
#ifdef CONFIG_NET_POLL_CONTROLLER
ndev->poll_controller = &dm9000_poll_controller;
#endif
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地址的源是eeprom*/
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);
/*如果从eeprom中读取的地址无效，并且私有数据不为空，从platform_device的私有数据中获取dev_addr*/
if (!is_valid_ether_addr(ndev->dev_addr) && pdata != NULL) {
mac_src = "platform data";
memcpy(ndev->dev_addr, pdata->dev_addr, 6);
}
/*如果地址依然无效，从PAR:物理地址(MAC)寄存器(Physical Address Register)中读取*/
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); // by bai
ndev->dev_addr[i] = ne_def_eth_mac_addr[i];
}
/*查看以太网网卡设备地址是否有效*/
if (!is_valid_ether_addr(ndev->dev_addr))
dev_warn(db->dev, "%s: Invalid ethernet MAC address. Please "
"set using ifconfig\n", ndev->name);
/*将ndev保存到pdev->dev->driver_data中*/
platform_set_drvdata(pdev, ndev);
/*一切都初始化好后，注册网络设备*/
ret = register_netdev(ndev);
if (ret == 0) {
DECLARE_MAC_BUF(mac);
printk(KERN_INFO "%s: dm9000%c at %p,%p IRQ %d MAC: %s (%s)\n",
ndev->name, dm9000_type_to_char(db->type),
db->io_addr, db->io_data, ndev->irq,
print_mac(mac, ndev->dev_addr), mac_src);
}
return 0;
out:
dev_err(db->dev, "not found (%d).\n", ret);
/*失败时,释放资源*/
dm9000_release_board(pdev, db);
free_netdev(ndev);
return ret;
}