利用ZYNQ SOC快速開啟演算法驗證通路（6）——LWIP實現千兆TCP/IP網路傳輸

TCP/IP Zynq 演算法 · 發表 2018-10-28 18:39:00

摘要：一、前言之前ZYNQ與PC之間的網路連線依賴於外接硬體協議棧晶片，雖然C驅動非常簡單，但網路頻寬受限。現採用LWIP+PS端MAC控制器+PHY晶片的通用架構。關於LWIP庫，已經有很多現成的資料和書籍。其有兩套API，一個是SOCKET，另一個是本例中要用到的RAW。RAW API...

一、前言

之前ZYNQ與PC之間的網路連線依賴於外接硬體協議棧晶片，雖然C驅動非常簡單，但網路頻寬受限。現採用LWIP+PS端MAC控制器+PHY晶片的通用架構。關於LWIP庫，已經有很多現成的資料和書籍。其有兩套API，一個是SOCKET，另一個是本例中要用到的RAW。RAW API理解起來較為複雜，整個程式基於中斷機制執行，通過函式指標完成多層回撥函式的執行。SOCKET API需要支援多執行緒作業系統的支援，也犧牲了效率，但理解和程式設計都較為容易。實際上SOCKET API是對RAW API的進一步封裝。

二、LWIP Echo Server demo解讀

首先開啟Xilinx SDK自帶的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 * XILINXBE 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 {
 75print(msg);
 76xil_printf("%d.%d.%d.%d\n\r", ip4_addr1(ip), ip4_addr2(ip), 
 77ip4_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 
 84print_ip("Board IP: ", ip);
 85print_ip("Netmask : ", mask);
 86print_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 {
104struct ip_addr ipaddr, netmask, gw;
105 
106/* the mac address of the board. this should be unique per board */
107unsigned char mac_ethernet_address[] =
108{ 0x00, 0x0a, 0x35, 0x00, 0x01, 0x02 };
109 
110echo_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
113ProgramSi5324();
114ProgramSfpPhy();
115 #endif
116 #endif
117 
118 /* Define this board specific macro in order perform PHY reset on ZCU102 */
119 #ifdef XPS_BOARD_ZCU102
120IicPhyReset();
121 #endif
122 
123init_platform();
124 
125 #if LWIP_DHCP==1
126ipaddr.addr = 0;
127gw.addr = 0;
128netmask.addr = 0;
129 #else
130/* initliaze IP addresses to be used */
131IP4_ADDR(&ipaddr,192, 168,1, 10);
132IP4_ADDR(&netmask, 255, 255, 255,0);
133IP4_ADDR(&gw,192, 168,1,1);
134 #endif
135print_app_header();
136 
137lwip_init();//網路引數初始化
138 
139/* Add network interface to the netif_list, and set it as default */
140if (!xemac_add(echo_netif, &ipaddr, &netmask,
141&gw, mac_ethernet_address,
142PLATFORM_EMAC_BASEADDR)) {
143xil_printf("Error adding N/W interface\n\r");
144return -1;
145}
146netif_set_default(echo_netif);
147 
148/* now enable interrupts */
149platform_enable_interrupts();
150 
151/* specify that the network if is up */
152netif_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*/
159dhcp_start(echo_netif);
160dhcp_timoutcntr = 24;
161 
162while(((echo_netif->ip_addr.addr) == 0) && (dhcp_timoutcntr > 0))
163xemacif_input(echo_netif);
164 
165if (dhcp_timoutcntr <= 0) {
166if ((echo_netif->ip_addr.addr) == 0) {
167xil_printf("DHCP Timeout\r\n");
168xil_printf("Configuring default IP of 192.168.1.10\r\n");
169IP4_ADDR(&(echo_netif->ip_addr),192, 168,1, 10);
170IP4_ADDR(&(echo_netif->netmask), 255, 255, 255,0);
171IP4_ADDR(&(echo_netif->gw),192, 168,1,1);
172}
173}
174 
175ipaddr.addr = echo_netif->ip_addr.addr;
176gw.addr = echo_netif->gw.addr;
177netmask.addr = echo_netif->netmask.addr;
178 #endif
179 
180print_ip_settings(&ipaddr, &netmask, &gw);//列印關鍵網路引數
181 
182/* start the application (web server, rxtest, txtest, etc..) */
183start_application();//設定回撥函式，這些函式在特定事件發生時以函式指標的方式被呼叫
184 
185/* receive and process packets */
186while (1) {
187if (TcpFastTmrFlag) {//傳送處理，如差錯重傳，通過定時器置位標誌位
188tcp_fasttmr();
189TcpFastTmrFlag = 0;
190}
191if (TcpSlowTmrFlag) {
192tcp_slowtmr();
193TcpSlowTmrFlag = 0;
194}
195xemacif_input(echo_netif);//連續接收資料包，並將資料包存入LWIP
196transfer_data();//空函式
197}
198
199/* never reached */
200cleanup_platform();
201 
202return 0;
203 }

echo

整體流程為：初始化LWIP、新增網路介面（MAC）、使能中斷、設定回撥函式。最終進入主迴圈，內部不斷檢測定時器中斷標誌位，當標誌位TcpFastTmrFlag或TcpSlowTmrFlag為1則呼叫相應的處理函式，完成超時重傳等任務。接下來查看回調函式的設定：


int start_application()
{
struct tcp_pcb *pcb;//protocol control block 簡稱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;
}

start_application

建立PCB（protocol control block）建立連線、繫結IP地址和埠號、監聽請求，最後tcp_accept函式用於指定當監聽到連線請求時呼叫的函式accept_callback。進入該函式內部檢視：


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

accept_callback

內部主要通過tcp_recv函式來指定當收到TCP包後呼叫的函式recv_callback。我們再次觀察其內容：


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

recv_callback

tcp_recved函式指示用來告知LWIP接收資料量，然後檢測傳送緩衝區是否足夠容納接收內容，若大於則呼叫tcp_write函式將接收資料寫入傳送緩衝區等待發送。綜上，整體的呼叫流程為：tcp_accept -> accept_callback -> tcp_recv -> recv_callback -> tcp_recved和tcp_write。前四個用於接收，後兩個用於傳送。

函式解析完畢，之後改動上位機網路引數，使PC機IP地址與Board在同一網段內，這裡設定為192.168.1.11.開啟網路除錯助手，設定PC為TCP Client。以下是ZYNQ串列埠列印及網路除錯結果。

三、TCP Client Send data

現在我們來改動demo，設計一個客戶端傳送資料包的示例工程，功能是迴圈傳送一個常數陣列中資料到遠端伺服器。該工程參考米聯客教程中相關章節內容。程式碼如下：


/******************************************************************************
*
* 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
* XILINXBE 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;
}

main

函式定義：


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 //靜態全域性函式 外部檔案不可見
 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 {
 30err_t err;
 31struct tcp_pcb *tpcb = connected_pcb;
 32 
 33if (!tpcb)
 34return -1;
 35 
 36//判斷髮送資料長度是否小於傳送緩衝區剩餘可用長度
 37if (TX_SIZE < tcp_sndbuf(tpcb)) {
 38//Write data for sending (but does not send it immediately).
 39err = tcp_write(tpcb, data, TX_SIZE, 1);
 40if (err != ERR_OK) {
 41xil_printf("txperf: Error on tcp_write: %d\r\n", err);
 42connected_pcb = NULL;
 43return -1;
 44}
 45 
 46//Find out what we can send and send it
 47err = tcp_output(tpcb);
 48if (err != ERR_OK) {
 49xil_printf("txperf: Error on tcp_output: %d\r\n",err);
 50return -1;
 51}
 52}
 53else
 54xil_printf("no space in tcp_sndbuf\n\r");
 55 
 56return 0;
 57 }
 58 
 59 static err_t tcp_sent_callback(void *arg, struct tcp_pcb *tpcb,u16_t len)
 60 {
 61tcp_trans_done ++;
 62return ERR_OK;
 63 }
 64 
 65 //tcp連接回調函式 設定為靜態函式，外部檔案不可見
 66 static err_t tcp_connected_callback(void *arg, struct tcp_pcb *tpcb, err_t err)
 67 {
 68/* store state */
 69connected_pcb = tpcb;
 70 
 71/* set callback values & functions */
 72tcp_arg(tpcb, NULL);
 73 
 74//傳送到遠端主機後呼叫tcp_sent_callback
 75tcp_sent(tpcb, tcp_sent_callback);
 76 
 77client_connected = 1;
 78 
 79/* initiate data transfer */
 80return ERR_OK;
 81 }
 82 
 83 int client_application()
 84 {
 85struct tcp_pcb *pcb;
 86struct ip_addr ipaddr;
 87err_t err;
 88unsigned port = 7;
 89 
 90/* create new TCP PCB structure */
 91pcb = tcp_new();
 92if (!pcb) {
 93xil_printf("Error creating PCB. Out of Memory\n\r");
 94return -1;
 95}
 96 
 97/* connect to iperf tcp server */
 98IP4_ADDR(&ipaddr,192, 168,1, 209);//設定要連線的主機的地址
 99 
100//當連線到主機時，呼叫tcp_connected_callback
101err = tcp_connect(pcb, &ipaddr, port, tcp_connected_callback);
102if (err != ERR_OK) {
103xil_printf("txperf: tcp_connect returned error: %d\r\n", err);
104return err;
105}
106 
107return 0;
108 }

tcp_trans

可以看出還是一樣的套路，在client_application函式中設定回撥函式。首先新建PCB，tcp_connect函式設定要連線遠端伺服器的IP地址和埠號，連線建立時將呼叫回撥函式tcp_connected_callback。tcp_connected_callback內部tcp_sent函式用於指定當傳送資料包完成後執行的tcp_sent_callback。tcp_sent_callback內部只利用tcp_trans_done變數計數傳送次數。而真正的傳送處理任務則交給主迴圈中的send_data。若處於連線狀態，且傳送緩衝區容量比帶傳送資料量大，則呼叫tcp_write將待發送資料寫入傳送緩衝區，之後呼叫tcp_output函式立即傳輸傳送緩衝區內容。如果不呼叫tcp_output，LWIP會等待資料量達到一定值時一起傳送來提高效率，是否呼叫tcp_output函式可根據具體需求而定。

接下來看下實驗結果：

PC端正確接收到常數陣列，實驗無誤。

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

參考文獻：

1 LWIP 無OS RAW-API 函式 - 專注的力量 - CSDN部落格 https://blog.csdn.net/liang890319/article/details/8574603

2 解讀TCP 四種定時器 - xiaofei0859的專欄 - CSDN部落格 https://blog.csdn.net/xiaofei0859/article/details/52794576

3 米聯《ZYNQ SOC修煉祕籍》

利用ZYNQ SOC快速開啟演算法驗證通路（6）——LWIP實現千兆TCP/IP網路傳輸

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