From 5f9163af4bf6b54ea08f7fef112e9fcf4a669e56 Mon Sep 17 00:00:00 2001
From: Richard Cochran <richardcochran@gmail.com>
Date: Sat, 17 Mar 2018 12:12:59 -0700
Subject: [PATCH] transport: Introduce method for fetching a deferred transmit
 time stamp.

When a messages is sent with the DEFER_EVENT flag, the lower transport
code does not fetch the time stamp right away.  This patch introduces
a method that allows a second call to retrieve the waiting transmit
time stamp.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
 transport.c | 11 +++++++++++
 transport.h | 13 +++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/transport.c b/transport.c
index ff5e307..8fb94de 100644
--- a/transport.c
+++ b/transport.c
@@ -66,6 +66,17 @@ int transport_sendto(struct transport *t, struct fdarray *fda,
 	return t->send(t, fda, event, 0, msg, len, &msg->address, &msg->hwts);
 }
 
+int transport_txts(struct transport *t, struct fdarray *fda,
+		   struct ptp_message *msg)
+{
+	int cnt, len = ntohs(msg->header.messageLength);
+	struct hw_timestamp *hwts = &msg->hwts;
+	unsigned char pkt[1600];
+
+	cnt = sk_receive(fda->fd[FD_EVENT], pkt, len, NULL, hwts, MSG_ERRQUEUE);
+	return cnt > 0 ? 0 : cnt;
+}
+
 int transport_physical_addr(struct transport *t, uint8_t *addr)
 {
 	if (t->physical_addr) {
diff --git a/transport.h b/transport.h
index 171e59f..4f6dc36 100644
--- a/transport.h
+++ b/transport.h
@@ -101,6 +101,19 @@ int transport_peer(struct transport *t, struct fdarray *fda,
 int transport_sendto(struct transport *t, struct fdarray *fda,
 		     enum transport_event event, struct ptp_message *msg);
 
+/**
+ * Fetches the transmit time stamp for a PTP message that was sent
+ * with the TRANS_DEFER_EVENT flag.
+ *
+ * @param t	The transport.
+ * @param fda	The array of descriptors filled in by transport_open.
+ * @param msg	The message previously sent using transport_send(),
+ *              transport_peer(), or transport_sendto().
+ * @return	Zero on success, or negative value in case of an error.
+ */
+int transport_txts(struct transport *t, struct fdarray *fda,
+		   struct ptp_message *msg);
+
 /**
  * Returns the transport's type.
  */