利用ZYNQ SOC快速打开算法验证通路（6）——LWIP实现千兆TCP/IP网络传输
程序员文章站
2022-10-16 17:00:01
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 ......
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.%d\n\r", 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 interface\n\r");
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 timeout\r\n");
168 xil_printf("configuring default ip of 192.168.1.10\r\n");
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 }
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 memory\n\r");
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 = %d\n\r", 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_listen\n\r");
return -3;
}
/* specify callback to use for incoming connections */
tcp_accept(pcb, accept_callback);
xil_printf("tcp echo server started @ port %d\n\r", port);
return 0;
}
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 }
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_sndbuf\n\r");
20
21 /* free the received pbuf */
22 pbuf_free(p);
23
24 return err_ok;
25 }
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.%d\n\r", 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 interface\n\r");
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;
}
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: %d\r\n", 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: %d\r\n",err);
50 return -1;
51 }
52 }
53 else
54 xil_printf("no space in tcp_sndbuf\n\r");
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 memory\n\r");
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: %d\r\n", err);
104 return err;
105 }
106
107 return 0;
108 }
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
2 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》