• linuxptp源码研究

    目录

    1. 检查网卡是否支持相应的时间戳

    2. linuxptp的目录架构

    3. ptp4l的大致流程分析

    4. gptp协议对应的sync, follow-up, delay-request, delay-response消息在代码的位置

    5.slave收到消息如何处理并调整时间：

    6.一个完整的时间同步的例子

    gptp的报文格式： 报文格式地图——重庆网管博客

    1. 检查网卡是否支持相应的时间戳

    • 通过终端命令ethtool -T eth0查看

    否则可能出现以下这种：eth0网卡不支持软时间戳（-S）对应的SOF_TIMESTAMPING_TX_SOFTWARE，SOF_TIMESTAMPING_RX_SOFTWARE，SOF_TIMESTAMPING_SOFTWARE，

    1. /usrdata # ./ptp4l -i eth0 -m -S
    2. ptp4l[5430.909]: interface 'eth0' does not support requested timestamping mode
    • 找到打印出错的地方--
    1. 	/* Check the time stamping mode on each interface. */
    2. 	c->timestamping = timestamping;
    3. 	required_modes = clock_required_modes(c);
    4. 	STAILQ_FOREACH(iface, &config->interfaces, list) {
    5. 		memset(ts_label, 0, sizeof(ts_label));
    6. 		if (!rtnl_get_ts_device(interface_name(iface), ts_label))
    7. 			interface_set_label(iface, ts_label);
    8. 		interface_get_tsinfo(iface);
    9. 		if (interface_tsinfo_valid(iface) &&
    10. 		    !interface_tsmodes_supported(iface, required_modes)) {
    11. 			pr_err("interface '%s' does not support requested timestamping mode",
    12. 			       interface_name(iface));
    13. 			return NULL;
    14. 		}

    config_get_int(config, NULL, "time_stamping");  // 配置的时间戳

    ----->clock_required_modes()  //逻辑上需要支持的时间戳：比如SOF_TIMESTAMPING_SOFTWARE， 

    SOF_TIMESTAMPING_TX_SOFTWARE，//发包的时间戳

    ----->interface_get_tsinfo ----->sk_get_ts_info

    • 创建socket---------------------fd = socket(AF_INET, SOCK_DGRAM, 0)
    • 通过socket去把信息放到ifr--------ioctl(fd, SIOCETHTOOL, &ifr);     //获取网卡支持的时间类型---和ethtool -T eth0 对应支持的时间戳应该一致

    ------>interface_tsinfo_valid()  和 interface_tsmodes_supported() 来确认这个网卡是否支持此时间模式

    2. linuxptp的目录架构

    研究目录下的makefile发现会编译出来几个APP：主要研究ptp4l， phc2sys这两个app

    • ptp4l：主要是用来计算得出两个设备之间的时间误差（时间戳相差的大小），频率误差（时间走的快慢的差异）。
    • phc2sys：主要是把两个时钟进行同步，比如把systime同步到phc时钟(ptp hardware clock)

    3. ptp4l的大致流程分析

    LinuxPTP的ptp4l.c文件有个int main()函数，makefile通过这个main函数会编译出来ptp4l的可执行程序。

    • 简单的说就是通过getopt_long()函数拿到配置的参数，然后通过clock_create创建一个时钟，在通过poll处理这个时钟相关的事件。
    1. int main(int argc, char *argv[])
    2. {
    3. ......拿到配置对应的参数
    4. 	while (EOF != (c = getopt_long(argc, argv, "MAEP246HSLf:i:p:sl:mqvh",
    5. 				       opts, &index))) { ......}
    6.  
    7. ......创建时钟
    8. 	clock = clock_create(type, cfg, req_phc);
    9. ......
    10. 	while (is_running()) {
    11.       实时的处理poll得到的clock对应的事件
    12. 		if (clock_poll(clock))  
    13. 			break;
    14. 	}
    15. ......
    16. }
    • clock_create函数
    1. struct clock *clock_create(enum clock_type type, struct config *config,
    2. 			   const char *phc_device)
    3. {
    4. ....一些参数配置
    5. ....检查 -i [dev] -i参数指定的设备是否支持需要的时间戳类型
    6. 	/* Check the time stamping mode on each interface. */
    7. 	c->timestamping = timestamping;
    8. 	required_modes = clock_required_modes(c);
    9. 	STAILQ_FOREACH(iface, &config->interfaces, list) {
    10. 		memset(ts_label, 0, sizeof(ts_label));
    11. 		if (!rtnl_get_ts_device(interface_name(iface), ts_label))
    12. 			interface_set_label(iface, ts_label);
    13. 		interface_get_tsinfo(iface);
    14. 		if (interface_tsinfo_valid(iface) &&
    15. 		    !interface_tsmodes_supported(iface, required_modes)) {
    16. 			pr_err("interface '%s' does not support requested timestamping mode",
    17. 			       interface_name(iface));
    18. 			return NULL;
    19. 		}
    20. 	}
    21. ...... 打开ptp hardware clock 
    22. 		c->clkid = phc_open(phc);
    23. ......  通过拿到的clkid初始化clock
    24. 		clockadj_init(c->clkid);
    25. ...... 创建时间控制器，通过makefile的
    26. SERVOS	= linreg.o ntpshm.o nullf.o pi.o servo.o
    27. 可知，servos是一个接口类，通过servo_create()创建不同的控制器，
    28. 比如比例积分(pi)控制器，线性(linreg)控制器
    29. 	c->servo = servo_create(c->config, servo, -fadj, max_adj, sw_ts);
    30.  
    31. ...... port_open通过指定不同的phc_device来创建相应的回调函数：
    32.                         p->dispatch 和 p->event
    33.     c->uds_ro_port = port_open(phc_device, phc_index, timestamping, 0,
    34. 				   c->uds_ro_if, c);
    35. }

    clock_create函数最重要的两点：

    1. 检查指定的网卡设备是否支持需要的时间戳模式

    2. 通过port_open指定p->dispatch（事件处理分发机制）和p->event（事件有限元状态机的变化）

    4. gptp协议对应的sync, follow-up, delay-request, delay-response消息在代码的位置

    参考：以 ptp4l、E2E 为例的 Linuxptp 代码分析_悠扬侠的博客-CSDN博客_linuxptp源码分析

    之前说了clock_create创建了时钟：在port_open函数指定了事件处理的函数，因为我用到的是bc_event和bc_dispatch,所以以这两个为例子.

    参考的文章已经写的很清楚了：自己也大概的写下：

    1. port_dispatch接口函数里面调用了clock_create函数的p->dispatch方法，而                port_dispatch(p, event, 0);在clock_poll()函数中被一直调用，那么正常的运行状态，所有的事件都是从clock_poll()函数调用port_dispatch--->bc_dispatch
    2. 个人感觉：bc_dispatch做了一些预处理的操作，可以暂时忽略.
    3. 然后就在clock_poll函数调用port_event()接口函数，同样的会一路调用到bc_event()函数
    • master发送sync消息：port_tx_sync（）函数：这个函数发送了sync和follow-up报文

    --->port_prepare_and_send函数执行发送消息

    --->transport_send或者transport_sendto调用t->send方法发送数据

    {

    以UDP为例 

    t->send(t, fda, event, 0, msg, len, NULL, &msg->hwts); 对应的是 udp->t.send  = udp_send;

    --->udpsend调用sendto发送数据

    --->立刻调用sk_receive接收反馈的消息，这里是最开始的ioctrl函数指定了发送一条报文，需要从网口设备返回一个时间戳给应用层，如果网口对应的driver有问题，可能会收不到时间戳

    • 设置接口，拿到发送的系统时间戳
    1. {
    2. setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING,×tamping, sizeof(timestamping));
    3. setsockopt(fd, SOL_SOCKET, SO_SELECT_ERR_QUEUE,  &flags, sizeof(flags));
    4. }

    }

    • master发送follow-up报文：port_tx_sync
    • master发送delay-request报文：port_pdelay_request
    • slave收到sync报文处理：process_sync
    • slave收到follow-up报文处理：process_follow_up

    5.slave收到消息如何处理并调整时间：

    按照gptp协议的规定，master和slave之间交互了sync.follow-up,delay_requst, delay_response消息，会计算得出时间戳误差，频率误差。

    • 可以查代码看出：在process_follow_up和process_sync函数会调用port_syfufsm(p, event, m);函数（这函数用来切换收到master发来的消息之后的状态机），其中调用了port_synchronize（）函数来调整状态并通过port_dispatch分发事件
    • 关键就是通过slave端的几个状态的跳变完成对时间的同步：

    其中master offst对应的是clock_synchronize中的状态跳变，可以很容易看出：比较关键的就是S0到S1，调用了clockadj_step函数，完成对时间戳的改变

    • 还有需要注意：clockadj_step()函数调整的是clkid对应的时间（如果调整的时间是phc对应的clkid的时间，那么同步到系统时间需要用phc2sys这个app）
    1. 	switch (state) {
    2. 	case SERVO_UNLOCKED: // S0
    3. 		break;
    4. 	case SERVO_JUMP: //s1
    5. 		clockadj_set_freq(c->clkid, -adj);
    6. //调整时间戳的差值
    7. 		clockadj_step(c->clkid, -tmv_to_nanoseconds(c->master_offset)); 
    8. 		c->ingress_ts = tmv_zero();
    9. 		if (c->sanity_check) {
    10. 			clockcheck_set_freq(c->sanity_check, -adj);
    11. 			clockcheck_step(c->sanity_check,
    12. 					-tmv_to_nanoseconds(c->master_offset));
    13. 		}
    14. 		tsproc_reset(c->tsproc, 0);
    15. 		clock_step_window(c);
    16. 		break;
    17. 	case SERVO_LOCKED:
    18. //调整频率
    19. 		clock_synchronize_locked(c, adj);
    20. 		break;
    21. 	case SERVO_LOCKED_STABLE:
    22. 		if (c->write_phase_mode) {
    23. 			clockadj_set_phase(c->clkid, -offset);
    24. 			adj = 0;
    25. 		} else {
    26. 			clock_synchronize_locked(c, adj);
    27. 		}
    28. 		break;
    29. 	}
    • 调整的时间的日志

    1. s0，s1，s2 : 表示时钟伺服器的不同状态，s0表示未锁定，s1表示正在同步，s2表示锁定，锁定状态表示不会再发生阶跃行同步，只是缓慢调整

    6.一个完整的时间同步的例子

    • 交叉工具链编译内核的testptp.c文件
    1. /*
    2.  * PTP 1588 clock support - User space test program
    3.  *
    4.  * Copyright (C) 2010 OMICRON electronics GmbH
    5.  *
    6.  *  This program is free software; you can redistribute it and/or modify
    7.  *  it under the terms of the GNU General Public License as published by
    8.  *  the Free Software Foundation; either version 2 of the License, or
    9.  *  (at your option) any later version.
    10.  *
    11.  *  This program is distributed in the hope that it will be useful,
    12.  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
    13.  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    14.  *  GNU General Public License for more details.
    15.  *
    16.  *  You should have received a copy of the GNU General Public License
    17.  *  along with this program; if not, write to the Free Software
    18.  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
    19.  */
    20. #define _GNU_SOURCE
    21. #define __SANE_USERSPACE_TYPES__        /* For PPC64, to get LL64 types */
    22. #include 
    23. #include 
    24. #include 
    25. #include 
    26. #include 
    27. #include 
    28. #include 
    29. #include 
    30. #include 
    31. #include 
    32. #include 
    33. #include 
    34. #include 
    35. #include 
    36. #include 
    37. #include 
    38.  
    39. #include 
    40.  
    41. #define DEVICE "/dev/ptp0"
    42.  
    43. #ifndef ADJ_SETOFFSET
    44. #define ADJ_SETOFFSET 0x0100
    45. #endif
    46.  
    47. #ifndef CLOCK_INVALID
    48. #define CLOCK_INVALID -1
    49. #endif
    50.  
    51. /* clock_adjtime is not available in GLIBC < 2.14 */
    52. #if !__GLIBC_PREREQ(2, 14)
    53. #include 
    54. static int clock_adjtime(clockid_t id, struct timex *tx)
    55. {
    56. 	return syscall(__NR_clock_adjtime, id, tx);
    57. }
    58. #endif
    59.  
    60. static clockid_t get_clockid(int fd)
    61. {
    62. #define CLOCKFD 3
    63. #define FD_TO_CLOCKID(fd)	((~(clockid_t) (fd) << 3) | CLOCKFD)
    64.  
    65. 	return FD_TO_CLOCKID(fd);
    66. }
    67.  
    68. static void handle_alarm(int s)
    69. {
    70. 	printf("received signal %d\n", s);
    71. }
    72.  
    73. static int install_handler(int signum, void (*handler)(int))
    74. {
    75. 	struct sigaction action;
    76. 	sigset_t mask;
    77.  
    78. 	/* Unblock the signal. */
    79. 	sigemptyset(&mask);
    80. 	sigaddset(&mask, signum);
    81. 	sigprocmask(SIG_UNBLOCK, &mask, NULL);
    82.  
    83. 	/* Install the signal handler. */
    84. 	action.sa_handler = handler;
    85. 	action.sa_flags = 0;
    86. 	sigemptyset(&action.sa_mask);
    87. 	sigaction(signum, &action, NULL);
    88.  
    89. 	return 0;
    90. }
    91.  
    92. static long ppb_to_scaled_ppm(int ppb)
    93. {
    94. 	/*
    95. 	 * The 'freq' field in the 'struct timex' is in parts per
    96. 	 * million, but with a 16 bit binary fractional field.
    97. 	 * Instead of calculating either one of
    98. 	 *
    99. 	 *    scaled_ppm = (ppb / 1000) << 16  [1]
    100. 	 *    scaled_ppm = (ppb << 16) / 1000  [2]
    101. 	 *
    102. 	 * we simply use double precision math, in order to avoid the
    103. 	 * truncation in [1] and the possible overflow in [2].
    104. 	 */
    105. 	return (long) (ppb * 65.536);
    106. }
    107.  
    108. static int64_t pctns(struct ptp_clock_time *t)
    109. {
    110. 	return t->sec * 1000000000LL + t->nsec;
    111. }
    112.  
    113. static void usage(char *progname)
    114. {
    115. 	fprintf(stderr,
    116. 		"usage: %s [options]\n"
    117. 		" -a val     request a one-shot alarm after 'val' seconds\n"
    118. 		" -A val     request a periodic alarm every 'val' seconds\n"
    119. 		" -c         query the ptp clock's capabilities\n"
    120. 		" -d name    device to open\n"
    121. 		" -e val     read 'val' external time stamp events\n"
    122. 		" -f val     adjust the ptp clock frequency by 'val' ppb\n"
    123. 		" -g         get the ptp clock time\n"
    124. 		" -h         prints this message\n"
    125. 		" -i val     index for event/trigger\n"
    126. 		" -k val     measure the time offset between system and phc clock\n"
    127. 		"            for 'val' times (Maximum 25)\n"
    128. 		" -l         list the current pin configuration\n"
    129. 		" -L pin,val configure pin index 'pin' with function 'val'\n"
    130. 		"            the channel index is taken from the '-i' option\n"
    131. 		"            'val' specifies the auxiliary function:\n"
    132. 		"            0 - none\n"
    133. 		"            1 - external time stamp\n"
    134. 		"            2 - periodic output\n"
    135. 		" -p val     enable output with a period of 'val' nanoseconds\n"
    136. 		" -P val     enable or disable (val=1|0) the system clock PPS\n"
    137. 		" -s         set the ptp clock time from the system time\n"
    138. 		" -S         set the system time from the ptp clock time\n"
    139. 		" -t val     shift the ptp clock time by 'val' seconds\n"
    140. 		" -T val     set the ptp clock time to 'val' seconds\n",
    141. 		progname);
    142. }
    143.  
    144. int main(int argc, char *argv[])
    145. {
    146. 	struct ptp_clock_caps caps;
    147. 	struct ptp_extts_event event;
    148. 	struct ptp_extts_request extts_request;
    149. 	struct ptp_perout_request perout_request;
    150. 	struct ptp_pin_desc desc;
    151. 	struct timespec ts;
    152. 	struct timex tx;
    153.  
    154. 	static timer_t timerid;
    155. 	struct itimerspec timeout;
    156. 	struct sigevent sigevent;
    157.  
    158. 	struct ptp_clock_time *pct;
    159. 	struct ptp_sys_offset *sysoff;
    160.  
    161.  
    162. 	char *progname;
    163. 	unsigned int i;
    164. 	int c, cnt, fd;
    165.  
    166. 	char *device = DEVICE;
    167. 	clockid_t clkid;
    168. 	int adjfreq = 0x7fffffff;
    169. 	int adjtime = 0;
    170. 	int capabilities = 0;
    171. 	int extts = 0;
    172. 	int gettime = 0;
    173. 	int index = 0;
    174. 	int list_pins = 0;
    175. 	int oneshot = 0;
    176. 	int pct_offset = 0;
    177. 	int n_samples = 0;
    178. 	int periodic = 0;
    179. 	int perout = -1;
    180. 	int pin_index = -1, pin_func;
    181. 	int pps = -1;
    182. 	int seconds = 0;
    183. 	int settime = 0;
    184.  
    185. 	int64_t t1, t2, tp;
    186. 	int64_t interval, offset;
    187.  
    188. 	progname = strrchr(argv[0], '/');
    189. 	progname = progname ? 1+progname : argv[0];
    190. 	while (EOF != (c = getopt(argc, argv, "a:A:cd:e:f:ghi:k:lL:p:P:sSt:T:v"))) {
    191. 		switch (c) {
    192. 		case 'a':
    193. 			oneshot = atoi(optarg);
    194. 			break;
    195. 		case 'A':
    196. 			periodic = atoi(optarg);
    197. 			break;
    198. 		case 'c':
    199. 			capabilities = 1;
    200. 			break;
    201. 		case 'd':
    202. 			device = optarg;
    203. 			break;
    204. 		case 'e':
    205. 			extts = atoi(optarg);
    206. 			break;
    207. 		case 'f':
    208. 			adjfreq = atoi(optarg);
    209. 			break;
    210. 		case 'g':
    211. 			gettime = 1;
    212. 			break;
    213. 		case 'i':
    214. 			index = atoi(optarg);
    215. 			break;
    216. 		case 'k':
    217. 			pct_offset = 1;
    218. 			n_samples = atoi(optarg);
    219. 			break;
    220. 		case 'l':
    221. 			list_pins = 1;
    222. 			break;
    223. 		case 'L':
    224. 			cnt = sscanf(optarg, "%d,%d", &pin_index, &pin_func);
    225. 			if (cnt != 2) {
    226. 				usage(progname);
    227. 				return -1;
    228. 			}
    229. 			break;
    230. 		case 'p':
    231. 			perout = atoi(optarg);
    232. 			break;
    233. 		case 'P':
    234. 			pps = atoi(optarg);
    235. 			break;
    236. 		case 's':
    237. 			settime = 1;
    238. 			break;
    239. 		case 'S':
    240. 			settime = 2;
    241. 			break;
    242. 		case 't':
    243. 			adjtime = atoi(optarg);
    244. 			break;
    245. 		case 'T':
    246. 			settime = 3;
    247. 			seconds = atoi(optarg);
    248. 			break;
    249. 		case 'h':
    250. 			usage(progname);
    251. 			return 0;
    252. 		case '?':
    253. 		default:
    254. 			usage(progname);
    255. 			return -1;
    256. 		}
    257. 	}
    258.  
    259. 	fd = open(device, O_RDWR);
    260. 	if (fd < 0) {
    261. 		fprintf(stderr, "opening %s: %s\n", device, strerror(errno));
    262. 		return -1;
    263. 	}
    264.  
    265. 	clkid = get_clockid(fd);
    266. 	if (CLOCK_INVALID == clkid) {
    267. 		fprintf(stderr, "failed to read clock id\n");
    268. 		return -1;
    269. 	}
    270.  
    271. 	if (capabilities) {
    272. 		if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
    273. 			perror("PTP_CLOCK_GETCAPS");
    274. 		} else {
    275. 			printf("capabilities:\n"
    276. 			       "  %d maximum frequency adjustment (ppb)\n"
    277. 			       "  %d programmable alarms\n"
    278. 			       "  %d external time stamp channels\n"
    279. 			       "  %d programmable periodic signals\n"
    280. 			       "  %d pulse per second\n"
    281. 			       "  %d programmable pins\n"
    282. 			       "  %d cross timestamping\n",
    283. 			       caps.max_adj,
    284. 			       caps.n_alarm,
    285. 			       caps.n_ext_ts,
    286. 			       caps.n_per_out,
    287. 			       caps.pps,
    288. 			       caps.n_pins,
    289. 			       caps.cross_timestamping);
    290. 		}
    291. 	}
    292.  
    293. 	if (0x7fffffff != adjfreq) {
    294. 		memset(&tx, 0, sizeof(tx));
    295. 		tx.modes = ADJ_FREQUENCY;
    296. 		tx.freq = ppb_to_scaled_ppm(adjfreq);
    297. 		if (clock_adjtime(clkid, &tx)) {
    298. 			perror("clock_adjtime");
    299. 		} else {
    300. 			puts("frequency adjustment okay");
    301. 		}
    302. 	}
    303.  
    304. 	if (adjtime) {
    305. 		memset(&tx, 0, sizeof(tx));
    306. 		tx.modes = ADJ_SETOFFSET;
    307. 		tx.time.tv_sec = adjtime;
    308. 		tx.time.tv_usec = 0;
    309. 		if (clock_adjtime(clkid, &tx) < 0) {
    310. 			perror("clock_adjtime");
    311. 		} else {
    312. 			puts("time shift okay");
    313. 		}
    314. 	}
    315.  
    316. 	if (gettime) {
    317. 		if (clock_gettime(clkid, &ts)) {
    318. 			perror("clock_gettime");
    319. 		} else {
    320. 			printf("clock time: %ld.%09ld or %s",
    321. 			       ts.tv_sec, ts.tv_nsec, ctime(&ts.tv_sec));
    322. 		}
    323. 	}
    324.  
    325. 	if (settime == 1) {
    326. 		clock_gettime(CLOCK_REALTIME, &ts);
    327. 		if (clock_settime(clkid, &ts)) {
    328. 			perror("clock_settime");
    329. 		} else {
    330. 			puts("set time okay");
    331. 		}
    332. 	}
    333.  
    334. 	if (settime == 2) {
    335. 		clock_gettime(clkid, &ts);
    336. 		if (clock_settime(CLOCK_REALTIME, &ts)) {
    337. 			perror("clock_settime");
    338. 		} else {
    339. 			puts("set time okay");
    340. 		}
    341. 	}
    342.  
    343. 	if (settime == 3) {
    344. 		ts.tv_sec = seconds;
    345. 		ts.tv_nsec = 0;
    346. 		if (clock_settime(clkid, &ts)) {
    347. 			perror("clock_settime");
    348. 		} else {
    349. 			puts("set time okay");
    350. 		}
    351. 	}
    352.  
    353. 	if (extts) {
    354. 		memset(&extts_request, 0, sizeof(extts_request));
    355. 		extts_request.index = index;
    356. 		extts_request.flags = PTP_ENABLE_FEATURE;
    357. 		if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
    358. 			perror("PTP_EXTTS_REQUEST");
    359. 			extts = 0;
    360. 		} else {
    361. 			puts("external time stamp request okay");
    362. 		}
    363. 		for (; extts; extts--) {
    364. 			cnt = read(fd, &event, sizeof(event));
    365. 			if (cnt != sizeof(event)) {
    366. 				perror("read");
    367. 				break;
    368. 			}
    369. 			printf("event index %u at %lld.%09u\n", event.index,
    370. 			       event.t.sec, event.t.nsec);
    371. 			fflush(stdout);
    372. 		}
    373. 		/* Disable the feature again. */
    374. 		extts_request.flags = 0;
    375. 		if (ioctl(fd, PTP_EXTTS_REQUEST, &extts_request)) {
    376. 			perror("PTP_EXTTS_REQUEST");
    377. 		}
    378. 	}
    379.  
    380. 	if (list_pins) {
    381. 		int n_pins = 0;
    382. 		if (ioctl(fd, PTP_CLOCK_GETCAPS, &caps)) {
    383. 			perror("PTP_CLOCK_GETCAPS");
    384. 		} else {
    385. 			n_pins = caps.n_pins;
    386. 		}
    387. 		for (i = 0; i < n_pins; i++) {
    388. 			desc.index = i;
    389. 			if (ioctl(fd, PTP_PIN_GETFUNC, &desc)) {
    390. 				perror("PTP_PIN_GETFUNC");
    391. 				break;
    392. 			}
    393. 			printf("name %s index %u func %u chan %u\n",
    394. 			       desc.name, desc.index, desc.func, desc.chan);
    395. 		}
    396. 	}
    397.  
    398. 	if (oneshot) {
    399. 		install_handler(SIGALRM, handle_alarm);
    400. 		/* Create a timer. */
    401. 		sigevent.sigev_notify = SIGEV_SIGNAL;
    402. 		sigevent.sigev_signo = SIGALRM;
    403. 		if (timer_create(clkid, &sigevent, &timerid)) {
    404. 			perror("timer_create");
    405. 			return -1;
    406. 		}
    407. 		/* Start the timer. */
    408. 		memset(&timeout, 0, sizeof(timeout));
    409. 		timeout.it_value.tv_sec = oneshot;
    410. 		if (timer_settime(timerid, 0, &timeout, NULL)) {
    411. 			perror("timer_settime");
    412. 			return -1;
    413. 		}
    414. 		pause();
    415. 		timer_delete(timerid);
    416. 	}
    417.  
    418. 	if (periodic) {
    419. 		install_handler(SIGALRM, handle_alarm);
    420. 		/* Create a timer. */
    421. 		sigevent.sigev_notify = SIGEV_SIGNAL;
    422. 		sigevent.sigev_signo = SIGALRM;
    423. 		if (timer_create(clkid, &sigevent, &timerid)) {
    424. 			perror("timer_create");
    425. 			return -1;
    426. 		}
    427. 		/* Start the timer. */
    428. 		memset(&timeout, 0, sizeof(timeout));
    429. 		timeout.it_interval.tv_sec = periodic;
    430. 		timeout.it_value.tv_sec = periodic;
    431. 		if (timer_settime(timerid, 0, &timeout, NULL)) {
    432. 			perror("timer_settime");
    433. 			return -1;
    434. 		}
    435. 		while (1) {
    436. 			pause();
    437. 		}
    438. 		timer_delete(timerid);
    439. 	}
    440.  
    441. 	if (perout >= 0) {
    442. 		if (clock_gettime(clkid, &ts)) {
    443. 			perror("clock_gettime");
    444. 			return -1;
    445. 		}
    446. 		memset(&perout_request, 0, sizeof(perout_request));
    447. 		perout_request.index = index;
    448. 		perout_request.start.sec = ts.tv_sec + 2;
    449. 		perout_request.start.nsec = 0;
    450. 		perout_request.period.sec = 0;
    451. 		perout_request.period.nsec = perout;
    452. 		if (ioctl(fd, PTP_PEROUT_REQUEST, &perout_request)) {
    453. 			perror("PTP_PEROUT_REQUEST");
    454. 		} else {
    455. 			puts("periodic output request okay");
    456. 		}
    457. 	}
    458.  
    459. 	if (pin_index >= 0) {
    460. 		memset(&desc, 0, sizeof(desc));
    461. 		desc.index = pin_index;
    462. 		desc.func = pin_func;
    463. 		desc.chan = index;
    464. 		if (ioctl(fd, PTP_PIN_SETFUNC, &desc)) {
    465. 			perror("PTP_PIN_SETFUNC");
    466. 		} else {
    467. 			puts("set pin function okay");
    468. 		}
    469. 	}
    470.  
    471. 	if (pps != -1) {
    472. 		int enable = pps ? 1 : 0;
    473. 		if (ioctl(fd, PTP_ENABLE_PPS, enable)) {
    474. 			perror("PTP_ENABLE_PPS");
    475. 		} else {
    476. 			puts("pps for system time request okay");
    477. 		}
    478. 	}
    479.  
    480. 	if (pct_offset) {
    481. 		if (n_samples <= 0 || n_samples > 25) {
    482. 			puts("n_samples should be between 1 and 25");
    483. 			usage(progname);
    484. 			return -1;
    485. 		}
    486.  
    487. 		sysoff = calloc(1, sizeof(*sysoff));
    488. 		if (!sysoff) {
    489. 			perror("calloc");
    490. 			return -1;
    491. 		}
    492. 		sysoff->n_samples = n_samples;
    493.  
    494. 		if (ioctl(fd, PTP_SYS_OFFSET, sysoff))
    495. 			perror("PTP_SYS_OFFSET");
    496. 		else
    497. 			puts("system and phc clock time offset request okay");
    498.  
    499. 		pct = &sysoff->ts[0];
    500. 		for (i = 0; i < sysoff->n_samples; i++) {
    501. 			t1 = pctns(pct+2*i);
    502. 			tp = pctns(pct+2*i+1);
    503. 			t2 = pctns(pct+2*i+2);
    504. 			interval = t2 - t1;
    505. 			offset = (t2 + t1) / 2 - tp;
    506.  
    507. 			printf("system time: %lld.%u\n",
    508. 				(pct+2*i)->sec, (pct+2*i)->nsec);
    509. 			printf("phc    time: %lld.%u\n",
    510. 				(pct+2*i+1)->sec, (pct+2*i+1)->nsec);
    511. 			printf("system time: %lld.%u\n",
    512. 				(pct+2*i+2)->sec, (pct+2*i+2)->nsec);
    513. 			printf("system/phc clock time offset is %" PRId64 " ns\n"
    514. 			       "system     clock time delay  is %" PRId64 " ns\n",
    515. 				offset, interval);
    516. 		}
    517.  
    518. 		free(sysoff);
    519. 	}
    520.  
    521. 	close(fd);
    522. 	return 0;
    523. }

    master：

    • ./ptp4l -i eth0 -E -m -l 7 -S -4 & 

    把带时间戳的报文通过ptp报文发送给slave端，用的是systime
    slave: [选择/dev/ptp1是发现在clokadj_step的时候对应的clkid对应的设备是/dev/ptp1，需要根据调试过程动态调整]

    • ./testptp -d /dev/ptp1 -s    //把systime设到/dev/ptp1时间
    • ./ptp4l -i pfe2 -m -4 -E -S -s

     拿到master过来的systime，计算得到的offset是master和slave之间的systime的误差，而在调用clockadj_step的时候用的是两边系统时间的offset。所以需要保证clockadj_step对应的clkid的时间和系统时间是一样的！！

    • ./testptp -d /dev/ptp1 -S    //把/dev/ptp1时间设到systime

    或者

    • ./phc2sys -l 7 -m -c CLOCK_REALTIME -s /dev/ptp1 -w &

    把/dev/ptp1对应的phc时间同步到systime， 

    -w是等待ptp4l： 通过pmc_create()来创建进程间通信，-w当收到了来自ptp4l的消息，就会跳出 Waiting for ptp4l...的循环，然后执行do_loop来执行 update_clock()来跟新时间（把/dev/ptp1上的时间更新到CLOCK_REALTIME上！！）

    • ./testptp -d /dev/ptp1 -k 1  //打印系统，/dev/ptp1时间

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  • 原文地址：https://blog.csdn.net/m0_37844072/article/details/126270366