From 36951376198a395cc6db0ee3d85037fca2dad9ea Mon Sep 17 00:00:00 2001
From: Richard Cochran <richardcochran@gmail.com>
Date: Thu, 16 May 2013 16:31:45 +0200
Subject: [PATCH] Let the clock servo know the expected sync interval.

This patch adds a new servo method to let the algorithm know about the
master clock's reported sync message interval. This information can be
used by the servo to adapt its synchronization parameters.

Signed-off-by: Richard Cochran <richardcochran@gmail.com>
---
 clock.c         | 2 ++
 pi.c            | 5 +++++
 servo.c         | 5 +++++
 servo.h         | 7 +++++++
 servo_private.h | 2 ++
 5 files changed, 21 insertions(+)

diff --git a/clock.c b/clock.c
index f59e753..b097911 100644
--- a/clock.c
+++ b/clock.c
@@ -1127,6 +1127,8 @@ void clock_sync_interval(struct clock *c, int n)
 		pr_warning("summary_interval is too long");
 	}
 	c->stats.max_count = (1 << shift);
+
+	servo_sync_interval(c->servo, n < 0 ? 1.0 / (1 << -n) : 1 << n);
 }
 
 struct timePropertiesDS *clock_time_properties(struct clock *c)
diff --git a/pi.c b/pi.c
index 89080c4..d42bf0b 100644
--- a/pi.c
+++ b/pi.c
@@ -132,6 +132,10 @@ static double pi_sample(struct servo *servo,
 	return ppb;
 }
 
+static void pi_sync_interval(struct servo *servo, double interval)
+{
+}
+
 struct servo *pi_servo_create(int fadj, int max_ppb, int sw_ts)
 {
 	struct pi_servo *s;
@@ -142,6 +146,7 @@ struct servo *pi_servo_create(int fadj, int max_ppb, int sw_ts)
 
 	s->servo.destroy = pi_destroy;
 	s->servo.sample  = pi_sample;
+	s->servo.sync_interval = pi_sync_interval;
 	s->drift         = fadj;
 	s->maxppb        = max_ppb;
 	s->first_update  = 1;
diff --git a/servo.c b/servo.c
index a312ad1..45c5832 100644
--- a/servo.c
+++ b/servo.c
@@ -41,3 +41,8 @@ double servo_sample(struct servo *servo,
 {
 	return servo->sample(servo, offset, local_ts, state);
 }
+
+void servo_sync_interval(struct servo *servo, double interval)
+{
+	servo->sync_interval(servo, interval);
+}
diff --git a/servo.h b/servo.h
index 4d4a8e7..052740e 100644
--- a/servo.h
+++ b/servo.h
@@ -86,4 +86,11 @@ double servo_sample(struct servo *servo,
 		    uint64_t local_ts,
 		    enum servo_state *state);
 
+/**
+ * Inform a clock servo about the master's sync interval.
+ * @param servo   Pointer to a servo obtained via @ref servo_create().
+ * @param interval The sync interval in seconds.
+ */
+void servo_sync_interval(struct servo *servo, double interval);
+
 #endif
diff --git a/servo_private.h b/servo_private.h
index f9c151f..98c7db2 100644
--- a/servo_private.h
+++ b/servo_private.h
@@ -28,6 +28,8 @@ struct servo {
 	double (*sample)(struct servo *servo,
 			 int64_t offset, uint64_t local_ts,
 			 enum servo_state *state);
+
+	void (*sync_interval)(struct servo *servo, double interval);
 };
 
 #endif