最近一直在看linux網絡相關的東西, 做爲提高準備自己動手寫個網卡驅動, 手上剛好有一塊mini2440, 所以準備以mini2440的DM9000下刀。當然本人也是第一次寫網卡驅動, 所以希望大家看到不足的地方多海函和指教。
今天, 我們先搭一個網卡驅動的框架, 並不設計實際硬件。
首先先包含今天會用到的必要的頭文件:
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
定義調試和打印用的宏:
#undef LYDM9K_DEBUG
#define LYDM9K_DEBUG
#ifdef LYDM9K_DEBUG
#define printdbg(fmt, args...) \
printk("lydm9k[%s]:\t" fmt, __func__, ##args)
#else
#define printdbg(fmt, args...) \
do {} while(0)
#endif /* LYDM9K_DEBUG */
#define dm9kmsg(fmt, args...) \
printk("lydm9k[%s]:\t" fmt, __func__, ##args)
編寫module註冊函數和卸載函數:
static int __init lydm9k_init(void)
{
dm9kmsg("insert module lydm9k\n");
platform_device_register(&lydm9k_device);
return platform_driver_register(&lydm9k_driver);
}
static void __exit lydm9k_exit(void)
{
platform_device_unregister(&lydm9k_device);
platform_driver_unregister(&lydm9k_driver);
dm9kmsg("remove module lydm9k\n");
}
MODULE_LICENSE("GPL");
module_init(lydm9k_init);
module_exit(lydm9k_exit);
初始化網卡的device結構體:
struct lydm9k_plat_data {
unsigned char mac[6];
unsigned int watchdog_timeo_msecs;
};
static struct lydm9k_plat_data lydm9k_plat_data = {
.mac = {0x01, 0x02, 0x03, 0x04, 0x05, 0x06},
.watchdog_timeo_msecs = 5000,
};
static struct resource lydm9k_resource[] = {
};
static void lydm9k_device_release(struct device *dev)
{
printdbg("invoked\n");
}
static struct platform_device lydm9k_device = {
.name = "lydm9k",
.id = -1,
.num_resources = ARRAY_SIZE(lydm9k_resource),
.resource = lydm9k_resource,
.dev = {
.platform_data = &lydm9k_plat_data,
.release = lydm9k_device_release,
},
};
初始化網卡的driver結構體:
static struct platform_driver lydm9k_driver = {
.driver = {
.name = "lydm9k",
.owner = THIS_MODULE,
},
.probe = lydm9k_probe,
.remove = __devexit_p(lydm9k_remove),
};
網卡驅動的probe函數和remove函數:
static int __devinit lydm9k_probe(struct platform_device *pdev)
{
int ret;
struct net_device *ndev;
struct lydm9k_priv *priv;
struct lydm9k_plat_data *pdata = pdev->dev.platform_data;
printdbg("detect a dm9k device\n");
// 申請ndev空間
ndev = alloc_etherdev(sizeof(struct lydm9k_priv));
if (NULL == ndev)
{
dm9kmsg("fail to alloc_etherdev\n");
return -ENOMEM;
}
// 設置ndev的福設備爲pdev
SET_NETDEV_DEV(ndev, &pdev->dev);
// 設置ndev和pdev直接的關聯
platform_set_drvdata(pdev, ndev);
priv = netdev_priv(ndev);
priv->pdev = pdev;
// 設置操作函數集/mac/watchdog_timeo
ndev->netdev_ops = &lydm9k_ops;
ndev->watchdog_timeo =
msecs_to_jiffies(pdata->watchdog_timeo_msecs);
memcpy(ndev->dev_addr, pdata->mac, 6);
// 註冊網卡
ret = register_netdev(ndev);
if(0 > ret)
{
dm9kmsg("fail to register netdev\n");
return -ENOMEM;
}
// 設置ndev的父設備爲pdev
SET_NETDEV_DEV(ndev, &pdev->dev);
// 設置ndev和pdev直接的關聯
platform_set_drvdata(pdev, ndev);
priv = netdev_priv(ndev);
priv->pdev = pdev;
// 設置操作函數集/mac/watchdog_timeo
ndev->netdev_ops = &lydm9k_ops;
ndev->watchdog_timeo =
msecs_to_jiffies(pdata->watchdog_timeo_msecs);
memcpy(ndev->dev_addr, pdata->mac, 6);
// 註冊網卡
ret = register_netdev(ndev);
if(0 > ret)
{
dm9kmsg("fail to register netdev\n");
goto failure_register_netdev;
}
return 0;
failure_register_netdev:
platform_set_drvdata(pdev, NULL);
free_netdev(ndev);
return ret;
}
static int __devexit lydm9k_remove(struct platform_device *pdev)
{
struct net_device *ndev = platform_get_drvdata(pdev);
unregister_netdev(ndev);
platform_set_drvdata(pdev, NULL);
free_netdev(ndev);
printdbg("remove ok\n");
return 0;
}
其中網卡的私有數據結構需要包含的數據先不深入分析,等後續用到了再追加,爲了簡單先定義成如下:
struct lydm9k_priv {
struct platform_device *pdev;
};
以及網卡的相關操作函數也都先定義幾個成空的示意用:
static int lydm9k_open(struct net_device *ndev)
{
printdbg("invoked\n");
return 0;
}
static int lydm9k_stop(struct net_device *ndev)
{
printdbg("invoked\n");
return 0;
}
static int lydm9k_start_xmit( struct sk_buff *skb,
struct net_device *ndev)
{
printdbg("invoked\n");
return 0;
}
static void lydm9k_timeout(struct net_device *ndev)
{
printdbg("invoked\n");
}
static struct net_device_ops lydm9k_ops = {
.ndo_open = lydm9k_open,
.ndo_stop = lydm9k_stop,
.ndo_start_xmit = lydm9k_start_xmit,
.ndo_tx_timeout = lydm9k_timeout,
};
OK,簡單的網卡驅動框架就搭好了, 然後是Makgefile:
ifneq ($(KERNELRELEASE),)
obj-m := lydm9k.o
else
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD := $(shell pwd)
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
endif
clean:
rm -rf *.mod.c *.mod.o *.o *.order *.symvers
rm -rf .*.ko.cmd .*.o.cmd .tmp_versions
make, 裝載驅動insmod lydm9k.ko, 然後dmesg, 可以看到如下打印信息(在PC機上即可):
[ 3949.452062] lydm9k[lydm9k_init]: insert module lydm9k
[ 3949.453609] lydm9k[lydm9k_probe]: detect a dm9k device
[ 3949.469968] lydm9k[lydm9k_open]: invoked
[ 3949.484108] lydm9k[lydm9k_start_xmit]: invoked
[ 3949.920047] lydm9k[lydm9k_start_xmit]: invoked
[ 3950.928047] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.020927] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.081567] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.095994] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.332173] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.583247] lydm9k[lydm9k_start_xmit]: invoked
[ 3951.783516] lydm9k[lydm9k_start_xmit]: invoked
[ 3952.021169] lydm9k[lydm9k_start_xmit]: invoked
[ 3952.208043] lydm9k[lydm9k_start_xmit]: invoked
ifconfig, 可以看到系統裏多出了一快網卡(MAC地址是01:02:03:04:05:06, 即我們在lydm9k_plat_data裏設置的地址):
eth1 Link encap:以太網 硬件地址 01:02:03:04:05:06
inet6 地址: fe80::302:3ff:fe04:506/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 躍點數:1
接收數據包:0 錯誤:0 丟棄:0 過載:0 幀數:0
發送數據包:0 錯誤:0 丟棄:0 過載:0 載波:0
碰撞:0 發送隊列長度:1000
接收字節:0 (0.0 B) 發送字節:0 (0.0 B)
OK, 今天就到此爲止, 明天繼續。