Linux网卡驱动程序编写

{

/*

*Thisisthefirstfieldofthevisiblepartofthisstructure

*(i.e.asseenbyusersintheSpace.cfile).Itisthename

*theinterface.

*/

char*name;

/*I/Ospecificfields-FIXME:Mergetheseandstructifmapintoone*/

unsignedlongrmem_end;/*shmemrecvend*/

unsignedlongrmem_start;/*shmemrecvstart*/

unsignedlongmem_end;/*sharedmemend*/

unsignedlongmem_start;/*sharedmemstart*/

unsignedlongbase_addr;/*deviceI/Oaddress*/

unsignedcharirq;/*deviceIRQnumber*/

/*Low-levelstatusflags.*/

volatileunsignedcharstart,/*startanoperation*/

interrupt;/*interruptarrived*/

/*在处理中断时interrupt设为1，处理完清0。*/

unsignedlongtbusy;/*transmitterbusymustbelongfor

bitops*/

structdevice*next;

/*Thedeviceinitializationfunction.Calledonlyonce.*/

/*指向驱动程序的初始化方法。*/

int(*init)(structdevice*dev);

/*Somehardwarealsoneedsthesefields,buttheyarenotpartofthe

usualsetspecifiedinSpace.c.*/

/*一些硬件可以在一块板上支持多个接口，可能用到if_port。*/

unsignedcharif_port;/*SelectableAUI,TP,..*/

unsignedchardma;/*DMAchannel*/

structenet_statistics*(*get_stats)(structdevice*dev);

/*

*Thismarkstheendofthevisiblepartofthestructure.All

*fieldshereafterareinternaltothesystem,andmaychangeat

*will(read:maybecleanedupatwill).

*/

/*Thesemaybeneededforfuturenetwork-power-downcode.*/

/*trans_start记录最后一次成功发送的时间。可以用来确定硬件是否工作正常。*/

unsignedlongtrans_start;/*Time(injiffies)oflastTx*/

unsignedlonglast_rx;/*TimeoflastRx*/

/*flags里面有很多内容，定义在include/linux/if.h里。*/

unsignedshortflags;/*interfaceflags(alaBSD)*/

unsignedshortfamily;/*addressfamilyID(AF_INET)*/

unsignedshortmetric;/*routingmetric(notused)*/

unsignedshortmtu;/*interfaceMTUvalue*/

/*type标明物理硬件的类型。主要说明硬件是否需要arp。定义在

include/linux/if_arp.h里。*/

unsignedshorttype;/*interfacehardwaretype*/

/*上层协议层根据hard_header_len在发送数据缓冲区前面预留硬件帧头空间。*/

unsignedshorthard_header_len;/*hardwarehdrlength*/

/*priv指向驱动程序自己定义的一些参数。*/

void*priv;/*pointertoprivatedata*/

/*Interfaceaddressinfo.*/

unsignedcharbroadcast[MAX_ADDR_LEN];/*hwbcastadd*/

unsignedcharpad;/*makedev_addralignedto8

bytes*/

unsignedchardev_addr[MAX_ADDR_LEN];/*hwaddress*/

unsignedcharaddr_len;/*hardwareaddresslength*/

unsignedlongpa_addr;/*protocoladdress*/

unsignedlongpa_brdaddr;/*protocolbroadcastaddr*/

unsignedlongpa_dstaddr;/*protocolP-Pothersideaddr*/

unsignedlongpa_mask;/*protocolnetmask*/

unsignedshortpa_alen;/*protocoladdresslength*/

structdev_mc_list*mc_list;/*Multicastmacaddresses*/

intmc_count;/*Numberofinstalledmcasts*/

structip_mc_list*ip_mc_list;/*IPmulticastfilterchain*/

__u32tx_queue_len;/*Maxframesperqueueallowed*/

/*Forloadbalancingdriverpairsupport*/

unsignedlongpkt_queue;/*Packetsqueued*/

structdevice*slave;/*Slavedevice*/

structnet_alias_info*alias_info;/*maindevaliasinfo*/

structnet_alias*my_alias;/*aliasdevs*/

/*Pointertotheinterfacebuffers.*/

structsk_buff_headbuffs[DEV_NUMBUFFS];

/*Pointerstointerfaceserviceroutines.*/

int(*open)(structdevice*dev);

int(*stop)(structdevice*dev);

int(*hard_start_xmit)(structsk_buff*skb,

structdevice*dev);

int(*hard_header)(structsk_buff*skb,

structdevice*dev,

unsignedshorttype,

void*daddr,

void*saddr,

unsignedlen);

int(*rebuild_header)(void*eth,structdevice*dev,

unsignedlongraddr,structsk_buff*skb);

#defineHAVE_MULTICAST

void(*set_multicast_list)(structdevice*dev);

#defineHAVE_SET_MAC_ADDR

int(*set_mac_address)(structdevice*dev,void*addr);

#defineHAVE_PRIVATE_IOCTL

int(*do_ioctl)(structdevice*dev,structifreq*ifr,intcmd);

#defineHAVE_SET_CONFIG

int(*set_config)(structdevice*dev,structifmap*map);

#defineHAVE_HEADER_CACHE

void(*header_cache_bind)(structhh_cache**hhp,structdevice

*dev,unsignedshorthtype,__u32daddr);

void(*header_cache_update)(structhh_cache*hh,structdevice

*dev,unsignedchar*haddr);

#defineHAVE_CHANGE_MTU

int(*change_mtu)(structdevice*dev,intnew_mtu);

structiw_statistics*(*get_wireless_stats)(structdevice*dev);

};

2.4常用的系统支持

2.4.1内存申请和释放

include/linux/kernel.h里声明了kmalloc()和kfree()。用于在内核模式下申请和释放内存。

void*kmalloc(unsignedintlen,intpriority);

voidkfree(void*__ptr);