一、前言

  之前ZYNQ与PC之间的网络连接依赖于外接硬件协议栈芯片,虽然C驱动非常简单,但网络带宽受限。现采用LWIP+PS端MAC控制器+PHY芯片的通用架构。关于LWIP库,已经有很多现成的资料和书籍。其有两套API,一个是SOCKET,另一个是本例中要用到的RAW。RAW API理解起来较为复杂,整个程序基于中断机制运行,通过函数指针完成多层回调函数的执行。SOCKET API需要支持多线程操作系统的支持,也牺牲了效率,但理解和编程都较为容易。实际上SOCKET API是对RAW API的进一步封装。

二、LWIP Echo Server demo解读

  首先打开Xilinx SDK自带的LwIP Echo Server demo.

  1 /******************************************************************************
  2 *
  3 * Copyright (C) 2009 - 2014 Xilinx, Inc.  All rights reserved.
  4 *
  5 * Permission is hereby granted, free of charge, to any person obtaining a copy
  6 * of this software and associated documentation files (the "Software"), to deal
  7 * in the Software without restriction, including without limitation the rights
  8 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  9 * copies of the Software, and to permit persons to whom the Software is
 10 * furnished to do so, subject to the following conditions:
 11 *
 12 * The above copyright notice and this permission notice shall be included in
 13 * all copies or substantial portions of the Software.
 14 *
 15 * Use of the Software is limited solely to applications:
 16 * (a) running on a Xilinx device, or
 17 * (b) that interact with a Xilinx device through a bus or interconnect.
 18 *
 19 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 22 * XILINX  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
 23 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
 24 * OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 25 * SOFTWARE.
 26 *
 27 * Except as contained in this notice, the name of the Xilinx shall not be used
 28 * in advertising or otherwise to promote the sale, use or other dealings in
 29 * this Software without prior written authorization from Xilinx.
 30 *
 31 ******************************************************************************/
 32 
 33 #include <stdio.h>
 34 
 35 #include "xparameters.h"
 36 
 37 #include "netif/xadapter.h"
 38 
 39 #include "platform.h"
 40 #include "platform_config.h"
 41 #if defined (__arm__) || defined(__aarch64__)
 42 #include "xil_printf.h"
 43 #endif
 44 
 45 #include "lwip/tcp.h"
 46 #include "xil_cache.h"
 47 
 48 #if LWIP_DHCP==1
 49 #include "lwip/dhcp.h"
 50 #endif
 51 
 52 /* defined by each RAW mode application */
 53 void print_app_header();
 54 int start_application();
 55 int transfer_data();
 56 void tcp_fasttmr(void);
 57 void tcp_slowtmr(void);
 58 
 59 /* missing declaration in lwIP */
 60 void lwip_init();
 61 
 62 #if LWIP_DHCP==1
 63 extern volatile int dhcp_timoutcntr;
 64 err_t dhcp_start(struct netif *netif);
 65 #endif
 66 
 67 extern volatile int TcpFastTmrFlag;
 68 extern volatile int TcpSlowTmrFlag;
 69 static struct netif server_netif;
 70 struct netif *echo_netif;
 71 
 72 void
 73 print_ip(char *msg, struct ip_addr *ip) 
 74 {
 75     print(msg);
 76     xil_printf("%d.%d.%d.%dnr", ip4_addr1(ip), ip4_addr2(ip), 
 77             ip4_addr3(ip), ip4_addr4(ip));
 78 }
 79 
 80 void
 81 print_ip_settings(struct ip_addr *ip, struct ip_addr *mask, struct ip_addr *gw)
 82 {
 83 
 84     print_ip("Board IP: ", ip);
 85     print_ip("Netmask : ", mask);
 86     print_ip("Gateway : ", gw);
 87 }
 88 
 89 #if defined (__arm__) && !defined (ARMR5)
 90 #if XPAR_GIGE_PCS_PMA_SGMII_CORE_PRESENT == 1 || XPAR_GIGE_PCS_PMA_1000BASEX_CORE_PRESENT == 1
 91 int ProgramSi5324(void);
 92 int ProgramSfpPhy(void);
 93 #endif
 94 #endif
 95 
 96 #ifdef XPS_BOARD_ZCU102
 97 #ifdef XPAR_XIICPS_0_DEVICE_ID
 98 int IicPhyReset(void);
 99 #endif
100 #endif
101 
102 int main()
103 {
104     struct ip_addr ipaddr, netmask, gw;
105 
106     /* the mac address of the board. this should be unique per board */
107     unsigned char mac_ethernet_address[] =
108     { 0x00, 0x0a, 0x35, 0x00, 0x01, 0x02 };
109 
110     echo_netif = &server_netif;
111 #if defined (__arm__) && !defined (ARMR5)
112 #if XPAR_GIGE_PCS_PMA_SGMII_CORE_PRESENT == 1 || XPAR_GIGE_PCS_PMA_1000BASEX_CORE_PRESENT == 1
113     ProgramSi5324();
114     ProgramSfpPhy();
115 #endif
116 #endif
117 
118 /* Define this board specific macro in order perform PHY reset on ZCU102 */
119 #ifdef XPS_BOARD_ZCU102
120     IicPhyReset();
121 #endif
122 
123     init_platform();
124 
125 #if LWIP_DHCP==1
126     ipaddr.addr = 0;
127     gw.addr = 0;
128     netmask.addr = 0;
129 #else
130     /* initliaze IP addresses to be used */
131     IP4_ADDR(&ipaddr,  192, 168,   1, 10);
132     IP4_ADDR(&netmask, 255, 255, 255,  0);
133     IP4_ADDR(&gw,      192, 168,   1,  1);
134 #endif    
135     print_app_header();
136 
137     lwip_init();//网络参数初始化
138 
139       /* Add network interface to the netif_list, and set it as default */
140     if (!xemac_add(echo_netif, &ipaddr, &netmask,
141                         &gw, mac_ethernet_address,
142                         PLATFORM_EMAC_BASEADDR)) {
143         xil_printf("Error adding N/W interfacenr");
144         return -1;
145     }
146     netif_set_default(echo_netif);
147 
148     /* now enable interrupts */
149     platform_enable_interrupts();
150 
151     /* specify that the network if is up */
152     netif_set_up(echo_netif);
153 
154 #if (LWIP_DHCP==1)
155     /* Create a new DHCP client for this interface.
156      * Note: you must call dhcp_fine_tmr() and dhcp_coarse_tmr() at
157      * the predefined regular intervals after starting the client.
158      */
159     dhcp_start(echo_netif);
160     dhcp_timoutcntr = 24;
161 
162     while(((echo_netif->ip_addr.addr) == 0) && (dhcp_timoutcntr > 0))
163         xemacif_input(echo_netif);
164 
165     if (dhcp_timoutcntr <= 0) {
166         if ((echo_netif->ip_addr.addr) == 0) {
167             xil_printf("DHCP Timeoutrn");
168             xil_printf("Configuring default IP of 192.168.1.10rn");
169             IP4_ADDR(&(echo_netif->ip_addr),  192, 168,   1, 10);
170             IP4_ADDR(&(echo_netif->netmask), 255, 255, 255,  0);
171             IP4_ADDR(&(echo_netif->gw),      192, 168,   1,  1);
172         }
173     }
174 
175     ipaddr.addr = echo_netif->ip_addr.addr;
176     gw.addr = echo_netif->gw.addr;
177     netmask.addr = echo_netif->netmask.addr;
178 #endif
179 
180     print_ip_settings(&ipaddr, &netmask, &gw);//打印关键网络参数
181 
182     /* start the application (web server, rxtest, txtest, etc..) */
183     start_application();//设置回调函数,这些函数在特定事件发生时以函数指针的方式被调用
184 
185     /* receive and process packets */
186     while (1) {
187         if (TcpFastTmrFlag) {//发送处理,如差错重传,通过定时器置位标志位
188             tcp_fasttmr();
189             TcpFastTmrFlag = 0;
190         }
191         if (TcpSlowTmrFlag) {
192             tcp_slowtmr();
193             TcpSlowTmrFlag = 0;
194         }
195         xemacif_input(echo_netif);//连续接收数据包,并将数据包存入LWIP
196         transfer_data();//空函数
197     }
198   
199     /* never reached */
200     cleanup_platform();
201 
202     return 0;
203 }
echo

  整体流程为:初始化LWIP、添加网络接口(MAC)、使能中断、设置回调函数。最终进入主循环,内部不断检测定时器中断标志位,当标志位TcpFastTmrFlag或TcpSlowTmrFlag为1则调用相应的处理函数,完成超时重传等任务。接下来查看回调函数的设置:

int start_application()
{
    struct tcp_pcb *pcb;//protocol control block 简称PCB
    err_t err;
    unsigned port = 7;

    /* create new TCP PCB structure */
    pcb = tcp_new();
    if (!pcb) {
        xil_printf("Error creating PCB. Out of Memorynr");
        return -1;
    }

    /* bind to specified @port */
    err = tcp_bind(pcb, IP_ADDR_ANY, port);
    if (err != ERR_OK) {
        xil_printf("Unable to bind to port %d: err = %dnr", port, err);
        return -2;
    }

    /* we do not need any arguments to callback functions */
    tcp_arg(pcb, NULL);

    /* listen for connections */
    pcb = tcp_listen(pcb);
    if (!pcb) {
        xil_printf("Out of memory while tcp_listennr");
        return -3;
    }

    /* specify callback to use for incoming connections */
    tcp_accept(pcb, accept_callback);

    xil_printf("TCP echo server started @ port %dnr", port);

    return 0;
}
start_application

  创建PCB(protocol control block)建立连接、绑定IP地址和端口号、监听请求,最后tcp_accept函数用于指定当监听到连接请求时调用的函数accept_callback。进入该函数内部查看:

 1 err_t accept_callback(void *arg, struct tcp_pcb *newpcb, err_t err)
 2 {
 3     static int connection = 1;
 4 
 5     /* set the receive callback for this connection */
 6     tcp_recv(newpcb, recv_callback);
 7 
 8     /* just use an integer number indicating the connection id as the
 9        callback argument */
10     tcp_arg(newpcb, (void*)(UINTPTR)connection);
11 
12     /* increment for subsequent accepted connections */
13     connection++;
14 
15     return ERR_OK;
16 }
accept_callback

  内部主要通过tcp_recv函数来指定当收到TCP包后调用的函数recv_callback。我们再次观察其内容:

 1 err_t recv_callback(void *arg, struct tcp_pcb *tpcb,
 2                                struct pbuf *p, err_t err)
 3 {
 4     /* do not read the packet if we are not in ESTABLISHED state */
 5     if (!p) {
 6         tcp_close(tpcb);
 7         tcp_recv(tpcb, NULL);
 8         return ERR_OK;
 9     }
10 
11     /* indicate that the packet has been received */
12     tcp_recved(tpcb, p->len);
13 
14     /* echo back the payload */
15     /* in this case, we assume that the payload is < TCP_SND_BUF */
16     if (tcp_sndbuf(tpcb) > p->len) {
17         err = tcp_write(tpcb, p->payload, p->len, 1);
18     } else
19         xil_printf("no space in tcp_sndbufnr");
20 
21     /* free the received pbuf */
22     pbuf_free(p);
23 
24     return ERR_OK;
25 }
recv_callback

  tcp_recved函数指示用来告知LWIP接收数据量,然后检测发送缓冲区是否足够容纳接收内容,若大于则调用tcp_write函数将接收数据写入发送缓冲区等待发送。综上,整体的调用流程为:tcp_accept -> accept_callback -> tcp_recv -> recv_callback -> tcp_recved和tcp_write。前四个用于接收,后两个用于发送。

  函数解析完毕,之后改动上位机网络参数,使PC机IP地址与Board在同一网段内,这里设置为192.168.1.11.打开网络调试助手,设置PC为TCP Client。以下是ZYNQ串口打印及网络调试结果。 

     

  

 

三、TCP Client Send data

  现在我们来改动demo,设计一个客户端发送数据包的示例工程,功能是循环发送一个常数数组中数据到远程服务器。该工程参考米联客教程中相关章节内容。代码如下:

/******************************************************************************
*
* Copyright (C) 2009 - 2014 Xilinx, Inc.  All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* Use of the Software is limited solely to applications:
* (a) running on a Xilinx device, or
* (b) that interact with a Xilinx device through a bus or interconnect.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* XILINX  BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF
* OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*
* Except as contained in this notice, the name of the Xilinx shall not be used
* in advertising or otherwise to promote the sale, use or other dealings in
* this Software without prior written authorization from Xilinx.
*
******************************************************************************/

#include <stdio.h>

#include "xparameters.h"

#include "netif/xadapter.h"

#include "platform.h"
#include "platform_config.h"
#if defined (__arm__) || defined(__aarch64__)
#include "xil_printf.h"
#endif

#include "lwip/tcp.h"
#include "xil_cache.h"

#if LWIP_DHCP==1
#include "lwip/dhcp.h"
#endif

/* defined by each RAW mode application */
void print_app_header();
int client_application();
//int start_application();
//int transfer_data();
int send_data();
void tcp_fasttmr(void);
void tcp_slowtmr(void);

/* missing declaration in lwIP */
void lwip_init();

#if LWIP_DHCP==1
extern volatile int dhcp_timoutcntr;
err_t dhcp_start(struct netif *netif);
#endif

extern volatile int TcpFastTmrFlag;
extern volatile int TcpSlowTmrFlag;
static struct netif server_netif;
struct netif *echo_netif;

void
print_ip(char *msg, struct ip_addr *ip) 
{
    print(msg);
    xil_printf("%d.%d.%d.%dnr", ip4_addr1(ip), ip4_addr2(ip), 
            ip4_addr3(ip), ip4_addr4(ip));
}

void
print_ip_settings(struct ip_addr *ip, struct ip_addr *mask, struct ip_addr *gw)
{

    print_ip("Board IP: ", ip);
    print_ip("Netmask : ", mask);
    print_ip("Gateway : ", gw);
}


int main()
{
    uint cycle = 0;
    struct ip_addr ipaddr, netmask, gw;

    /* the mac address of the board. this should be unique per board */
    unsigned char mac_ethernet_address[] =
    { 0x00, 0x0a, 0x35, 0x00, 0x01, 0x02 };

    echo_netif = &server_netif;

/* Define this board specific macro in order perform PHY reset on ZCU102 */


    init_platform();

    /* initliaze IP addresses to be used */
    IP4_ADDR(&ipaddr,  192, 168,   1, 10);
    IP4_ADDR(&netmask, 255, 255, 255,  0);
    IP4_ADDR(&gw,      192, 168,   1,  1);

    print_app_header();

    lwip_init();

      /* Add network interface to the netif_list, and set it as default */
    if (!xemac_add(echo_netif, &ipaddr, &netmask,
                        &gw, mac_ethernet_address,
                        PLATFORM_EMAC_BASEADDR)) {
        xil_printf("Error adding N/W interfacenr");
        return -1;
    }
    netif_set_default(echo_netif);

    /* now enable interrupts */
    platform_enable_interrupts();

    /* specify that the network if is up */
    netif_set_up(echo_netif);

    print_ip_settings(&ipaddr, &netmask, &gw);

    /* start the application (web server, rxtest, txtest, etc..) */
    //start_application();
    client_application();

    /* receive and process packets */
    while (1) {
        if (TcpFastTmrFlag) {
            tcp_fasttmr();
            TcpFastTmrFlag = 0;
        }
        if (TcpSlowTmrFlag) {
            tcp_slowtmr();
            TcpSlowTmrFlag = 0;
        }
        xemacif_input(echo_netif);
        //transfer_data();
        if(cycle == 9999){
            cycle = 0;
            send_data();
        }
        else
            cycle++;
    }
  

    return 0;
}
main

  函数定义:

  1 /*
  2  * tcp_trans.c
  3  *
  4  *  Created on: 2018年10月18日
  5  *      Author: s
  6  */
  7 
  8 
  9 #include <stdio.h>
 10 #include <string.h>
 11 
 12 #include "lwip/err.h"
 13 #include "lwip/tcp.h"
 14 #include "lwipopts.h"
 15 #include "xil_cache.h"
 16 #include "xil_printf.h"
 17 #include "sleep.h"
 18 
 19 #define TX_SIZE 10
 20 
 21 static struct tcp_pcb*connected_pcb = NULL;
 22 unsigned client_connected = 0;
 23 //静态全局函数 外部文件不可见
 24 uint tcp_trans_done = 0;
 25 
 26 u_char data[TX_SIZE] = {0,1,2,3,4,5,6,7,8,9};
 27 
 28 int send_data()
 29 {
 30     err_t err;
 31     struct tcp_pcb *tpcb = connected_pcb;
 32 
 33     if (!tpcb)
 34         return -1;
 35 
 36     //判断发送数据长度是否小于发送缓冲区剩余可用长度
 37     if (TX_SIZE < tcp_sndbuf(tpcb)) {
 38         //Write data for sending (but does not send it immediately).
 39         err = tcp_write(tpcb, data, TX_SIZE, 1);
 40         if (err != ERR_OK) {
 41             xil_printf("txperf: Error on tcp_write: %drn", err);
 42             connected_pcb = NULL;
 43             return -1;
 44         }
 45 
 46         //Find out what we can send and send it
 47         err = tcp_output(tpcb);
 48         if (err != ERR_OK) {
 49             xil_printf("txperf: Error on tcp_output: %drn",err);
 50             return -1;
 51         }
 52     }
 53     else
 54         xil_printf("no space in tcp_sndbufnr");
 55 
 56     return 0;
 57 }
 58 
 59 static err_t tcp_sent_callback(void *arg, struct tcp_pcb *tpcb,u16_t len)
 60 {
 61     tcp_trans_done ++;
 62     return ERR_OK;
 63 }
 64 
 65 //tcp连接回调函数 设置为静态函数,外部文件不可见
 66 static err_t tcp_connected_callback(void *arg, struct tcp_pcb *tpcb, err_t err)
 67 {
 68     /* store state */
 69     connected_pcb = tpcb;
 70 
 71     /* set callback values & functions */
 72     tcp_arg(tpcb, NULL);
 73 
 74     //发送到远程主机后调用tcp_sent_callback
 75     tcp_sent(tpcb, tcp_sent_callback);
 76 
 77     client_connected = 1;
 78 
 79     /* initiate data transfer */
 80     return ERR_OK;
 81 }
 82 
 83 int client_application()
 84 {
 85     struct tcp_pcb *pcb;
 86     struct ip_addr ipaddr;
 87     err_t err;
 88     unsigned port = 7;
 89 
 90     /* create new TCP PCB structure */
 91     pcb = tcp_new();
 92     if (!pcb) {
 93         xil_printf("Error creating PCB. Out of Memorynr");
 94         return -1;
 95     }
 96 
 97     /* connect to iperf tcp server */
 98     IP4_ADDR(&ipaddr,  192, 168,   1, 209);//设置要连接的主机的地址
 99 
100     //当连接到主机时,调用tcp_connected_callback
101     err = tcp_connect(pcb, &ipaddr, port, tcp_connected_callback);
102     if (err != ERR_OK) {
103         xil_printf("txperf: tcp_connect returned error: %drn", err);
104         return err;
105     }
106 
107     return 0;
108 }
tcp_trans

  可以看出还是一样的套路,在client_application函数中设置回调函数。首先新建PCB,tcp_connect函数设定要连接远程服务器的IP地址和端口号,连接建立时将调用回调函数tcp_connected_callback。tcp_connected_callback内部tcp_sent函数用于指定当发送数据包完成后执行的tcp_sent_callback。tcp_sent_callback内部只利用tcp_trans_done变量计数发送次数。而真正的发送处理任务则交给主循环中的send_data。若处于连接状态,且发送缓冲区容量比带发送数据量大,则调用tcp_write将待发送数据写入发送缓冲区,之后调用tcp_output函数立即传输发送缓冲区内容。如果不调用tcp_output,LWIP会等待数据量达到一定值时一起发送来提高效率,是否调用tcp_output函数可根据具体需求而定。

  接下来看下实验结果:

 

  PC端正确接收到常数数组,实验无误。

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

参考文献:

1 LWIP 无OS RAW-API 函数 - 专注的力量 - CSDN博客 https://blog.csdn.net/liang890319/article/details/8574603

解读TCP 四种定时器 - xiaofei0859的专栏 - CSDN博客 https://blog.csdn.net/xiaofei0859/article/details/52794576

3 米联 《ZYNQ SOC修炼秘籍》

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