// SPDX-License-Identifier: LGPL-2.1
/*
 * Copyright (C) 2019, VMware, Tzvetomir Stoyanov tz.stoyanov@gmail.com>
 *
 */

#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/types.h>
#include <linux/types.h>
#include <time.h>
#include <sched.h>
#include <limits.h>

#include "trace-cmd.h"
#include "trace-cmd-private.h"
#include "tracefs.h"
#include "trace-tsync-local.h"
#include "trace-msg.h"
#include "trace-cmd-local.h"

typedef __be32 be32;
typedef __u64 u64;
typedef __s64 s64;

#define PTP_SYNC_LOOP	339

#define PTP_SYNC_PKT_START	1
#define PTP_SYNC_PKT_PROBE	2
#define PTP_SYNC_PKT_PROBES	3
#define PTP_SYNC_PKT_OFFSET	4
#define PTP_SYNC_PKT_END	5

/* print time sync debug messages */
/* #define TSYNC_DEBUG */

struct ptp_clock_sync {
	struct tep_handle	*tep;
	struct tep_format_field	*id;
	int			raw_id;
	int			marker_fd;
	int			series_id;
	int			flags;
	int			debug_fd;
};

enum {
/*
 * Consider only the probe with fastest response time,
 * otherwise make a histogram from all probes.
 */
	PTP_FLAG_FASTEST_RESPONSE		= (1 << 0),
/*
 * Use trace marker to get the clock,
 * otherwise use the system clock directly.
 */
	PTP_FLAG_USE_MARKER			= (1 << 1),
};
static int ptp_flags = PTP_FLAG_FASTEST_RESPONSE | PTP_FLAG_USE_MARKER;

/*
 * Calculated using formula [CPU rate]*[calculated offset deviation]
 * tested on 3GHz CPU, with x86-tsc trace clock and compare the calculated
 * offset with /sys/kernel/debug/kvm/<VM ID>/vcpu0/tsc-offset
 * measured 2000ns deviation
 * using PTP flags PTP_FLAG_FASTEST_RESPONSE | PTP_FLAG_USE_MARKER
 */
#define PTP_ACCURACY	6000
#define PTP_NAME	"ptp"

struct ptp_clock_start_msg {
	be32	series_id;
	be32	flags;
} __packed;

struct ptp_clock_sample {
	s64		ts;
	be32		id;
} __packed;

struct ptp_clock_result_msg {
	be32			series_id;
	be32			count;
	struct ptp_clock_sample	samples[2*PTP_SYNC_LOOP];
} __packed;

struct ptp_clock_offset_msg {
	s64	ts;
	s64	offset;
};

struct ptp_markers_context {
	struct clock_sync_context	*clock;
	struct ptp_clock_sync		*ptp;
	struct ptp_clock_result_msg	msg;
	int				size;
};

struct ptp_marker_buf {
	int local_id;
	int remote_id;
	int count;
	int packet_id;
} __packed;

struct ptp_marker {
	int series_id;
	struct ptp_marker_buf data;
} __packed;

static int ptp_clock_sync_init(struct tracecmd_time_sync *tsync)
{
	const char *systems[] = {"ftrace", NULL};
	struct clock_sync_context *clock_context;
	struct ptp_clock_sync *ptp;
	struct tep_event *raw;
	char *path;

	if (!tsync || !tsync->context)
		return -1;
	clock_context = (struct clock_sync_context *)tsync->context;
	if (clock_context->proto_data)
		return 0;

	ptp = calloc(1, sizeof(struct ptp_clock_sync));
	if (!ptp)
		return -1;

	ptp->marker_fd = -1;
	ptp->debug_fd = -1;

	path = tracefs_instance_get_dir(clock_context->instance);
	if (!path)
		goto error;
	ptp->tep = tracefs_local_events_system(path, systems);
	tracefs_put_tracing_file(path);
	if (!ptp->tep)
		goto error;
	raw = tep_find_event_by_name(ptp->tep, "ftrace", "raw_data");
	if (!raw)
		goto error;
	ptp->id = tep_find_field(raw, "id");
	if (!ptp->id)
		goto error;
	ptp->raw_id = raw->id;

	tep_set_file_bigendian(ptp->tep, tracecmd_host_bigendian());
	tep_set_local_bigendian(ptp->tep, tracecmd_host_bigendian());

	path = tracefs_instance_get_file(clock_context->instance, "trace_marker_raw");
	if (!path)
		goto error;
	ptp->marker_fd = open(path, O_WRONLY);
	tracefs_put_tracing_file(path);

	clock_context->proto_data = ptp;

#ifdef TSYNC_DEBUG
	if (clock_context->is_server) {
		char buff[256];
		int res_fd;

		sprintf(buff, "res-id%d.txt", clock_context->remote_id);

		res_fd = open(buff, O_CREAT|O_WRONLY|O_TRUNC, 0644);
		if (res_fd > 0)
			close(res_fd);
	}
#endif

	return 0;

error:
	if (ptp) {
		tep_free(ptp->tep);
		if (ptp->marker_fd >= 0)
			close(ptp->marker_fd);
	}
	free(ptp);
	return -1;
}

static int ptp_clock_sync_free(struct tracecmd_time_sync *tsync)
{
	struct clock_sync_context *clock_context;
	struct ptp_clock_sync *ptp;

	if (!tsync || !tsync->context)
		return -1;
	clock_context = (struct clock_sync_context *)tsync->context;

	if (clock_context && clock_context->proto_data) {
		ptp = (struct ptp_clock_sync *)clock_context->proto_data;
		tep_free(ptp->tep);
		if (ptp->marker_fd >= 0)
			close(ptp->marker_fd);
		if (ptp->debug_fd >= 0)
			close(ptp->debug_fd);
		free(clock_context->proto_data);
		clock_context->proto_data = NULL;
	}
	return 0;
}

/* Save the timestamps of sent ('s') and returned ('r') probes in the
 * ctx->msg.samples[] array. Depending of the context (server or client), there
 * may be only returned probes, or both sent and returned probes. The returned
 * probes are saved first in the array, after them are the sent probes.
 * Depending of the context, the array can be with size:
 *  [0 .. max data.count] - holds only returned probes
 *  [0 .. 2 * max data.count] - holds both returned and sent probes
 */
static void ptp_probe_store(struct ptp_markers_context *ctx,
			    struct ptp_marker *marker,
			    unsigned long long ts)
{
	int index = -1;

	if (marker->data.packet_id == 'r' &&
	    marker->data.count <= ctx->size) {
		index = marker->data.count - 1;
	} else if (marker->data.packet_id == 's' &&
		  marker->data.count * 2 <= ctx->size){
		index = ctx->size / 2 + marker->data.count - 1;
	}

	if (index >= 0) {
		ctx->msg.samples[index].id = marker->data.count;
		ctx->msg.samples[index].ts = ts;
		ctx->msg.count++;
	}
}

static int ptp_marker_find(struct tep_event *event, struct tep_record *record,
			   int cpu, void *context)
{
	struct ptp_markers_context *ctx;
	struct ptp_marker *marker;

	ctx = (struct ptp_markers_context *)context;

	/* Make sure this is our event */
	if (event->id != ctx->ptp->raw_id || !ctx->ptp->id)
		return 0;
	if (record->size >= (ctx->ptp->id->offset + sizeof(struct ptp_marker))) {
		marker = (struct ptp_marker *)(record->data + ctx->ptp->id->offset);
		if (marker->data.local_id == ctx->clock->local_id &&
		    marker->data.remote_id == ctx->clock->remote_id &&
		    marker->series_id == ctx->ptp->series_id &&
		    marker->data.count)
			ptp_probe_store(ctx, marker, record->ts);
	}

	return 0;
}

static inline bool good_probe(struct ptp_clock_sample *server_sample,
			      struct ptp_clock_sample *send_sample,
			      struct ptp_clock_sample *client_sample,
			      int *bad_probes)
{
	if (server_sample->ts && send_sample->ts && client_sample->ts &&
	    server_sample->id == send_sample->id &&
	    server_sample->id == client_sample->id)
		return true;
	(*bad_probes)++;
	return false;
}

static int ptp_calc_offset_fastest(struct clock_sync_context *clock,
			   struct ptp_clock_result_msg *server,
			   struct ptp_clock_result_msg *client,
			   long long *offset_ret, long long *ts_ret,
			   int *bad_probes)
{
	struct ptp_clock_sample *sample_send;
	long long delta_min = LLONG_MAX;
	long long offset = 0;
	long long delta = 0;
	long long ts = 0;
	int max_i;
	int i;

	*bad_probes = 0;
	sample_send = server->samples + (server->count / 2);
	max_i = server->count / 2 < client->count ?
		server->count / 2 : client->count;
	for (i = 0; i < max_i; i++) {
		if (!good_probe(&server->samples[i], &sample_send[i],
		    &client->samples[i], bad_probes))
			continue;
		ts = (sample_send[i].ts + server->samples[i].ts) / 2;
		offset = client->samples[i].ts - ts;

		delta = server->samples[i].ts - sample_send[i].ts;
		if (delta_min > delta) {
			delta_min = delta;
			*offset_ret = offset;
			*ts_ret = ts;
		}
#ifdef TSYNC_DEBUG
		{
			struct ptp_clock_sync *ptp;

			ptp = (struct ptp_clock_sync *)clock->proto_data;
			if (ptp && ptp->debug_fd > 0) {
				char buff[256];

				sprintf(buff, "%lld %lld %lld\n",
					ts, client->samples[i].ts, offset);
				write(ptp->debug_fd, buff, strlen(buff));
			}
		}
#endif
	}

	return 0;
}

static int ptp_calc_offset_hist(struct clock_sync_context *clock,
			   struct ptp_clock_result_msg *server,
			   struct ptp_clock_result_msg *client,
			   long long *offset_ret, long long *ts_ret,
			   int *bad_probes)
{
	struct ptp_clock_sample *sample_send;
	long long timestamps[PTP_SYNC_LOOP];
	long long offsets[PTP_SYNC_LOOP];
	long long offset_min = LLONG_MAX;
	long long offset_max = 0;
	int hist[PTP_SYNC_LOOP];
	int ind, max = 0;
	long long bin;
	int i, k = 0;

	*bad_probes = 0;
	memset(hist, 0, sizeof(int) * PTP_SYNC_LOOP);
	sample_send = server->samples + (server->count / 2);
	for (i = 0; i * 2 < server->count && i < client->count; i++) {
		if (!good_probe(&server->samples[i], &sample_send[i],
		    &client->samples[i], bad_probes))
			continue;
		timestamps[k] = (sample_send[i].ts + server->samples[i].ts) / 2;
		offsets[k] = client->samples[i].ts - timestamps[k];
		if (offset_max < llabs(offsets[k]))
			offset_max = llabs(offsets[k]);
		if (offset_min > llabs(offsets[k]))
			offset_min = llabs(offsets[k]);
#ifdef TSYNC_DEBUG
		{
			struct ptp_clock_sync *ptp;

			ptp = (struct ptp_clock_sync *)clock->proto_data;

			if (ptp && ptp->debug_fd > 0) {
				char buff[256];

				sprintf(buff, "%lld %lld %lld\n",
					timestamps[k],
					client->samples[i].ts, offsets[k]);
				write(ptp->debug_fd, buff, strlen(buff));
			}
		}
#endif
		k++;
	}

	bin = (offset_max - offset_min) / PTP_SYNC_LOOP;
	for (i = 0; i < k; i++) {
		ind = (llabs(offsets[i]) - offset_min) / bin;
		if (ind < PTP_SYNC_LOOP) {
			hist[ind]++;
			if (max < hist[ind]) {
				max = hist[ind];
				*offset_ret = offsets[i];
				*ts_ret = timestamps[i];
			}
		}
	}

	return 0;
}

static void ntoh_ptp_results(struct ptp_clock_result_msg *msg)
{
	int i;

	msg->count = ntohl(msg->count);
	for (i = 0; i < msg->count; i++) {
		msg->samples[i].id = ntohl(msg->samples[i].id);
		msg->samples[i].ts = ntohll(msg->samples[i].ts);
	}
	msg->series_id = ntohl(msg->series_id);
}


static void hton_ptp_results(struct ptp_clock_result_msg *msg)
{
	int i;

	for (i = 0; i < msg->count; i++) {
		msg->samples[i].id = htonl(msg->samples[i].id);
		msg->samples[i].ts = htonll(msg->samples[i].ts);
	}
	msg->series_id = htonl(msg->series_id);
	msg->count = htonl(msg->count);
}

static inline void ptp_track_clock(struct ptp_markers_context *ctx,
				   struct ptp_marker *marker)
{
	if (ctx->ptp->flags & PTP_FLAG_USE_MARKER) {
		write(ctx->ptp->marker_fd, marker, sizeof(struct ptp_marker));
	} else {
		struct timespec clock;
		unsigned long long ts;

		clock_gettime(CLOCK_MONOTONIC_RAW, &clock);
		ts = clock.tv_sec * 1000000000LL;
		ts += clock.tv_nsec;
		ptp_probe_store(ctx, marker, ts);
	}
}

static int ptp_clock_client(struct tracecmd_time_sync *tsync,
			    long long *offset, long long *timestamp)
{
	char sync_proto[TRACECMD_TSYNC_PNAME_LENGTH];
	struct clock_sync_context *clock_context;
	struct ptp_clock_offset_msg res_offset;
	struct ptp_clock_start_msg start;
	struct ptp_markers_context ctx;
	struct ptp_clock_sync *ptp;
	struct ptp_marker marker;
	unsigned int sync_msg;
	unsigned int size;
	char *msg;
	int count;
	int ret;

	if (!tsync || !tsync->context || !tsync->msg_handle)
		return -1;

	clock_context = (struct clock_sync_context *)tsync->context;
	if (clock_context->proto_data == NULL)
		return -1;

	ptp = (struct ptp_clock_sync *)clock_context->proto_data;
	size = sizeof(start);
	msg = (char *)&start;
	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
					  sync_proto, &sync_msg,
					  &size, &msg);
	if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
	    sync_msg != PTP_SYNC_PKT_START)
		return -1;
	ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
					  PTP_SYNC_PKT_START, sizeof(start),
					  (char *)&start);
	marker.data.local_id = clock_context->local_id;
	marker.data.remote_id = clock_context->remote_id;
	marker.series_id = ntohl(start.series_id);
	marker.data.packet_id = 'r';
	ptp->series_id = marker.series_id;
	ptp->flags = ntohl(start.flags);
	msg = (char *)&count;
	size = sizeof(count);
	ctx.msg.count = 0;
	ctx.size = PTP_SYNC_LOOP;
	ctx.ptp = ptp;
	ctx.clock = clock_context;
	ctx.msg.series_id = ptp->series_id;
	while (true) {
		count = 0;
		ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
						  sync_proto, &sync_msg,
						  &size, &msg);
		if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
		    sync_msg != PTP_SYNC_PKT_PROBE || !ntohl(count))
			break;
		marker.data.count = ntohl(count);
		ptp_track_clock(&ctx, &marker);
		ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
						  PTP_SYNC_PKT_PROBE,
						  sizeof(count), (char *)&count);
		if (ret)
			break;
	}

	if (strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
	    sync_msg != PTP_SYNC_PKT_END)
		return -1;

	if (ptp->flags & PTP_FLAG_USE_MARKER)
		tracefs_iterate_raw_events(ptp->tep, clock_context->instance,
					   NULL, 0, ptp_marker_find, &ctx);

	hton_ptp_results(&ctx.msg);
	ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
					  PTP_SYNC_PKT_PROBES,
					  sizeof(ctx.msg), (char *)&ctx.msg);

	msg = (char *)&res_offset;
	size = sizeof(res_offset);
	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
					  sync_proto, &sync_msg,
					  &size, (char **)&msg);
	if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
	    sync_msg != PTP_SYNC_PKT_OFFSET)
		return -1;

	*offset = ntohll(res_offset.offset);
	*timestamp = ntohll(res_offset.ts);

	return 0;
}


static int ptp_clock_server(struct tracecmd_time_sync *tsync,
			    long long *offset, long long *timestamp)
{
	char sync_proto[TRACECMD_TSYNC_PNAME_LENGTH];
	struct ptp_clock_result_msg *results = NULL;
	struct clock_sync_context *clock_context;
	struct ptp_clock_offset_msg res_offset;
	struct ptp_clock_start_msg start;
	struct ptp_markers_context ctx;
	int sync_loop = PTP_SYNC_LOOP;
	struct ptp_clock_sync *ptp;
	struct ptp_marker marker;
	unsigned int sync_msg;
	unsigned int size;
	int bad_probes;
	int count = 1;
	int msg_count;
	int msg_ret;
	char *msg;
	int ret;

	if (!tsync || !tsync->context || !tsync->msg_handle)
		return -1;

	clock_context = (struct clock_sync_context *)tsync->context;
	if (clock_context->proto_data == NULL)
		return -1;

	ptp = (struct ptp_clock_sync *)clock_context->proto_data;
	ptp->flags = ptp_flags;
	memset(&start, 0, sizeof(start));
	start.series_id = htonl(ptp->series_id + 1);
	start.flags = htonl(ptp->flags);
	ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
					 PTP_SYNC_PKT_START, sizeof(start),
					 (char *)&start);
	if (!ret)
		ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
						  sync_proto, &sync_msg,
						  NULL, NULL);
	if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
	    sync_msg != PTP_SYNC_PKT_START)
		return -1;

	tracefs_instance_file_write(clock_context->instance, "trace", "\0");

	ptp->series_id++;
	marker.data.local_id = clock_context->local_id;
	marker.data.remote_id = clock_context->remote_id;
	marker.series_id = ptp->series_id;
	msg = (char *)&msg_ret;
	size = sizeof(msg_ret);
	ctx.size = 2*PTP_SYNC_LOOP;
	ctx.ptp = ptp;
	ctx.clock = clock_context;
	ctx.msg.count = 0;
	ctx.msg.series_id = ptp->series_id;
	do {
		marker.data.count = count++;
		marker.data.packet_id = 's';
		msg_count = htonl(marker.data.count);
		ptp_track_clock(&ctx, &marker);
		ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
						 PTP_SYNC_PKT_PROBE,
						 sizeof(msg_count),
						 (char *)&msg_count);
		if (!ret)
			ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
							  sync_proto, &sync_msg,
							  &size, &msg);

		marker.data.packet_id = 'r';
		ptp_track_clock(&ctx, &marker);
		if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
		    sync_msg != PTP_SYNC_PKT_PROBE ||
		    ntohl(msg_ret) != marker.data.count)
			break;
	} while (--sync_loop);

	if (sync_loop)
		return -1;

	ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
					  PTP_SYNC_PKT_END, 0, NULL);

	size = 0;
	ret = tracecmd_msg_recv_time_sync(tsync->msg_handle,
					  sync_proto, &sync_msg,
					  &size, (char **)&results);
	if (ret || strncmp(sync_proto, PTP_NAME, TRACECMD_TSYNC_PNAME_LENGTH) ||
	    sync_msg != PTP_SYNC_PKT_PROBES || size == 0 || results == NULL)
		return -1;

	ntoh_ptp_results(results);
	if (ptp->flags & PTP_FLAG_USE_MARKER)
		tracefs_iterate_raw_events(ptp->tep, clock_context->instance,
					   NULL, 0, ptp_marker_find, &ctx);
	if (ptp->flags & PTP_FLAG_FASTEST_RESPONSE)
		ptp_calc_offset_fastest(clock_context, &ctx.msg, results, offset,
					timestamp, &bad_probes);
	else
		ptp_calc_offset_hist(clock_context, &ctx.msg, results, offset,
				     timestamp, &bad_probes);
#ifdef TSYNC_DEBUG
	{
		char buff[256];
		int res_fd;

		sprintf(buff, "res-id%d.txt", clock_context->remote_id);

		res_fd = open(buff, O_WRONLY|O_APPEND, 0644);
		if (res_fd > 0) {
			if (*offset && *timestamp) {
				sprintf(buff, "%d %lld %lld\n",
					ptp->series_id, *offset, *timestamp);
				write(res_fd, buff, strlen(buff));
			}
			close(res_fd);
		}

		printf("\n calculated offset %d: %lld, %d probes, filtered out %d, PTP flags 0x%X\n\r",
			ptp->series_id, *offset, results->count, bad_probes, ptp->flags);
		if (ptp && ptp->debug_fd > 0) {
			sprintf(buff, "%lld %lld 0\n", *offset, *timestamp);
			write(ptp->debug_fd, buff, strlen(buff));
			close(ptp->debug_fd);
			ptp->debug_fd = -1;
		}

	}
#endif

	res_offset.offset = htonll(*offset);
	res_offset.ts = htonll(*timestamp);
	ret = tracecmd_msg_send_time_sync(tsync->msg_handle, PTP_NAME,
					  PTP_SYNC_PKT_OFFSET,
					  sizeof(res_offset),
					  (char *)&res_offset);

	free(results);
	return 0;
}

static int ptp_clock_sync_calc(struct tracecmd_time_sync *tsync,
			       long long *offset, long long *scaling, long long *frac,
			       long long *timestamp, unsigned int cpu)
{
	struct clock_sync_context *clock_context;
	int ret;

	if (!tsync || !tsync->context)
		return -1;
	clock_context = (struct clock_sync_context *)tsync->context;

#ifdef TSYNC_DEBUG
	if (clock_context->is_server) {
		struct ptp_clock_sync *ptp;
		char buff[256];

		ptp = (struct ptp_clock_sync *)clock_context->proto_data;
		if (ptp->debug_fd > 0)
			close(ptp->debug_fd);
		sprintf(buff, "s-id%d_%d.txt",
				clock_context->remote_id, ptp->series_id+1);
		ptp->debug_fd = open(buff, O_CREAT|O_WRONLY|O_TRUNC, 0644);
	}
#endif

	if (scaling)
		*scaling = 1;
	if (frac)
		*frac = 0;
	if (clock_context->is_server)
		ret = ptp_clock_server(tsync, offset, timestamp);
	else
		ret = ptp_clock_client(tsync, offset, timestamp);

	return ret;
}

int ptp_clock_sync_register(void)
{
	return tracecmd_tsync_proto_register(PTP_NAME, PTP_ACCURACY,
					     TRACECMD_TIME_SYNC_ROLE_GUEST |
					     TRACECMD_TIME_SYNC_ROLE_HOST |
					     TRACECMD_TIME_SYNC_ROLE_CLIENT |
					     TRACECMD_TIME_SYNC_ROLE_SERVER,
					     0, TRACECMD_TSYNC_FLAG_INTERPOLATE,
					     ptp_clock_sync_init,
					     ptp_clock_sync_free,
					     ptp_clock_sync_calc);

}

int ptp_clock_sync_unregister(void)
{
	return tracecmd_tsync_proto_unregister(PTP_NAME);
}