Degrade the sensor state from OK to WARNING and CRITICAL after periods of

ten minutes (same behaviour as nmea(4)).  If the cable is pulled, the sensor
no longer keeps the OK status forever.  Tested with a PEX511 as MSTS sender.

1 files changed, 56 insertions, 10 deletions

diff --git a/sys/kern/tty_msts.c b/sys/kern/tty_msts.c
index 128c3cc3746..5ba54209130 100644
--- a/sys/kern/tty_msts.c
+++ b/sys/kern/tty_msts.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: tty_msts.c,v 1.1 2008/01/05 17:33:28 mbalmer Exp $ */
+/*	$OpenBSD: tty_msts.c,v 1.2 2008/01/06 13:11:51 mbalmer Exp $ */
 
 /*
  * Copyright (c) 2008 Marc Balmer <mbalmer@openbsd.org>
@@ -46,8 +46,14 @@ void	mstsattach(int);
 
 #define MSTSMAX	32
 #define MAXFLDS	4
+#ifdef MSTS_DEBUG
+#define TRUSTTIME	30
+#else
+#define TRUSTTIME	(10 * 60)	/* 10 minutes */
+#endif
 
 int msts_count;	/* this is wrong, it should really be a SLIST */
+static int t_trust;
 
 struct msts {
 	char			cbuf[MSTSMAX];	/* receive buffer */
@@ -55,6 +61,7 @@ struct msts {
 	struct ksensordev	timedev;
 	struct timespec		ts;		/* current timestamp */
 	struct timespec		lts;		/* timestamp of last <STX> */
+	struct timeout		msts_tout;	/* invalidate sensor */
 	int64_t			gap;		/* gap between two sentences */
 	int64_t			last;		/* last time rcvd */
 	int			sync;		/* if 1, waiting for <STX> */
@@ -84,6 +91,7 @@ mstsopen(dev_t dev, struct tty *tp)
 {
 	struct proc *p = curproc;
 	struct msts *np;
+	struct timeval t;
 	int error;
 
 	DPRINTF(("mstsopen\n"));
@@ -107,8 +115,16 @@ mstsopen(dev_t dev, struct tty *tp)
 	if (error) {
 		free(np, M_DEVBUF);
 		tp->t_sc = NULL;
-	} else
+	} else {
 		sensordev_install(&np->timedev);
+		timeout_set(&np->msts_tout, msts_timeout, np);
+
+		/* convert timevals to hz */
+		t.tv_sec = TRUSTTIME;
+		t.tv_usec = 0;
+		t_trust = tvtohz(&t);
+	}
+
 	return error;
 }
 
@@ -118,6 +134,7 @@ mstsclose(struct tty *tp, int flags)
 	struct msts *np = (struct msts *)tp->t_sc;
 
 	tp->t_line = TTYDISC;	/* switch back to termios */
+	timeout_del(&np->msts_tout);
 	sensordev_deinstall(&np->timedev);
 	free(np, M_DEVBUF);
 	tp->t_sc = NULL;
@@ -248,6 +265,13 @@ msts_decode(struct msts *np, struct tty *tp, char *fld[], int fldcnt)
 	}
 	np->last = msts_now;
 	np->gap = 0LL;
+#ifdef MSTS_DEBUG
+	if (np->time.status == SENSOR_S_UNKNOWN) {
+		np->time.status = SENSOR_S_OK;
+		timeout_add(&np->msts_tout, t_trust);
+	}
+	np->gapno = 0;
+#endif
 
 	np->time.value = np->ts.tv_sec * 1000000000LL +
 	    np->ts.tv_nsec - msts_now;
@@ -259,15 +283,17 @@ msts_decode(struct msts *np, struct tty *tp, char *fld[], int fldcnt)
 		if (fldcnt != 13)
 			strlcpy(np->time.desc, "MSTS", sizeof(np->time.desc));
 	}
-	if (fld[3][0] == '#')
-		np->time.status = SENSOR_S_CRIT;
-	else if (fld[3][0] == ' ' && fld[3][1] == '*')
-		np->time.status = SENSOR_S_WARN;
-	else if (fld[3][0] == ' ' && fld[3][1] == ' ')
+	/*
+	 * only update the timeout if the clock reports the time a valid,
+	 * the status is reported in fld[3][0] and fld[3][1] as follows:
+	 * fld[3][0] == '#'				critical
+	 * fld[3][0] == ' ' && fld[3][1] == '*'		warning
+	 * fld[3][0] == ' ' && fld[3][1] == ' '		ok
+	 */
+	if (fld[3][0] == ' ' && fld[3][1] == ' ') {
 		np->time.status = SENSOR_S_OK;
-	else
-		DPRINTF(("msts: unknown clock status indication\n"));
-
+		timeout_add(&np->msts_tout, t_trust);
+	}
 	/*
 	 * If tty timestamping is requested, but not PPS signal is present, set
 	 * the sensor state to CRITICAL.
@@ -371,3 +397,23 @@ msts_time_to_nano(char *s, int64_t *nano)
 	*nano = secs * 1000000000LL;
 	return 0;
 }
+
+/*
+ * Degrade the sensor state if we received no MSTS string for more than
+ * TRUSTTIME seconds.
+ */
+void
+msts_timeout(void *xnp)
+{
+	struct msts *np = xnp;
+
+	if (np->time.status == SENSOR_S_OK) {
+		np->time.status = SENSOR_S_WARN;
+		/*
+		 * further degrade in TRUSTTIME seconds if no new valid MSTS
+		 * strings are received.
+		 */
+		timeout_add(&np->msts_tout, t_trust);
+	} else
+		np->time.status = SENSOR_S_CRIT;
+}