NIOS II网络驱动程序分析.doc

NIOS II网络驱动程序分析 网络是嵌入式应用的常备功能，在NIOS II中集成了UCOS II和LWIP，分析网络设备在NIOS II中的来龙去脉对学习NIOS II设备驱动程序有典型的意义。设备的定义和系统设备联表管理。1. 驱动程序提供的freedev_rtl8019.h中定义一个freedev_rtl8019_if结构的全局变量dev#define FREEDEV_RTL8019_INSTANCE(name, dev) freedev_rtl8019_if dev = ALT_LLIST_ENTRY, 0, name#_NAME, freedev_rtl8019_init, freedev_rtl8019_rx, , , name#_BASE, name#_IRQ, 8, 0, 0结构freedev_rtl8019_if定义如下：typedef struct alt_lwip_dev_list lwip_dev_list; int base_addr; int irq; int bus_width; sys_sem_t semaphore; sys_sem_t arp_semaphore; alt_u8 tx_packet_no; /* Number of packet allocated for Tx */freedev_rtl8019_if;相关结构定义如下：typedef struct alt_llist llist; /* for internal use */ alt_lwip_dev dev;alt_lwip_dev_list;struct alt_lwip_dev /* The netif pointer MUST be the first element in the structure */ struct netif *netif; const char* name; err_t (*init_routine)(struct netif*); void (*rx_routine)();struct netif /* pointer to next in linked list */ struct netif *next; /* IP address configuration in network byte order */ struct ip_addr ip_addr; struct ip_addr netmask; struct ip_addr gw; /* This function is called by the network device driver * to pass a packet up the TCP/IP stack. */ err_t (* input)(struct pbuf *p, struct netif *inp); /* This function is called by the IP module when it wants * to send a packet on the interface. This function typically * first resolves the hardware address, then sends the packet. */ err_t (* output)(struct netif *netif, struct pbuf *p,struct ip_addr *ipaddr); /* This function is called by the ARP module when it wants * to send a packet on the interface. This function outputs * the pbuf as-is on the link medium. */ err_t (* linkoutput)(struct netif *netif, struct pbuf *p); /* This field can be set by the device driver and could point * to state information for the device. */ void *state;#if LWIP_DHCP /* the DHCP client state information for this netif */ struct dhcp *dhcp;#endif /* number of bytes used in hwaddr */ unsigned char hwaddr_len; /* link level hardware address of this interface */ unsigned char hwaddrNETIF_MAX_HWADDR_LEN; /* maximum transfer unit (in bytes) */ u16_t mtu; /* flags (see NETIF_FLAG_ above) */ u8_t flags; /* link type */ u8_t link_type; /* descriptive abbreviation */ char name2; /* number of this interface */ u8_t num;由以上的结构可以分析得出：全局变量dev中包含了网络通讯的所有要素。2. 驱动程序中freedev_rtl8019.h中还定义了FREEDEV_RTL8019_INIT(name, dev)该宏定义最终调用alt_lwip_dev_reg(dev); 将设备全局变量注册到系统网络设备联表中。#define alt_lwip_dev_reg(dev) alt_llist_insert(&alt_lwip_device_list, &dev.lwip_dev_list.llist)alt_lwip_device_list是一个在alt_lwip_dev.c中定义的全局变量。第二个参数是alt_llist指针。alt_llist_insert完成双向联表插入操作。以上两个步骤在系统生成时从驱动程序.h文件中生成到alt_sys_init.c中。在系统运行时FREEDEV_RTL8019_INIT将被运行。设备初始化 在应用程序的函数main中首先调用lwip_stack_init。函数中提供了回调函数init_done_func初始化底层网络设备。lwip_stack_init(LWIP_TCPIP_TASK_PRIORITY, init_done_func, 0);lwip_stack_init初始化协议栈，在TCP线程工作前调用init_done_func函数。Init_done_func函数中对设备初始化的调用由以下函数完成，lwip_devices_i