[LinuxPPS] refclock_nmea patch

[Rodolfo Giometti]

On Mon, Oct 22, 2007 at 08:21:47PM +0200, Udo van den Heuvel wrote:
> Rodolfo Giometti wrote:
> > On Mon, Oct 22, 2007 at 08:04:12PM +0200, Udo van den Heuvel wrote:
> >> Udo van den Heuvel wrote:
> >>> Oct 22 19:19:53 epia ntpd[3499]: kernel time sync status 0040
> >>> Oct 22 19:19:53 epia ntpd[3499]: refclock_nmea: try alternate PPS device
> >>> /dev/pps0
> >>> Oct 22 19:19:53 epia ntpd[3499]: refclock_nmea: found PPS source
> >>> "/dev/pps%d" at id #6 on ""
> >>>
> >>> Note the %d in the message string and that the first gps0 device is not
> >>> used. 
> >> /sys/class/pps has a directory for pps0 but not for gps0.
> > 
> > This directory hold __only__ PPS devices.
> 
> The first pps device I offer is via /dev/gps0 and it is not used.

With "used" do you mean "used by ntpd as PPS source" or "used by ntpd
as GPS data source"?

The former is correct beacuse /dev/gps0 is _not_ a PPS source, it's a
serial line (points to /dev/ttyS0), the latter I don't know. :)

> >> Is my link from gps0 to /dev/ttyS0 in the way?
> > 
> > No.
> 
> So why is /dev/gps0 not used?
> 
> This puzzles me.
> 
> Udo

> --- /usr/src/redhat/ntp-4.2.4p2/ntpd/refclock_nmea.c	2006-06-06 22:16:53.000000000 +0200
> +++ refclock_nmea.c	2007-10-22 20:15:57.000000000 +0200
> @@ -61,6 +61,7 @@
>  # define DEVICE "COM%d:" 	/* COM 1 - 3 supported */
>  #else
>  # define DEVICE	"/dev/gps%d"	/* name of radio device */
> +# define DEVICEPPS "/dev/pps%d" /* name of alternate PPS radio device */
>  #endif
>  #define	SPEED232	B4800	/* uart speed (4800 bps) */
>  #define	PRECISION	(-9)	/* precision assumed (about 2 ms) */
> @@ -71,6 +72,7 @@
>  #define RANGEGATE	500000	/* range gate (ns) */
>  
>  #define LENNMEA		75	/* min timecode length */
> +#define LENPPS		PPS_MAX_NAME_LEN
>  
>  /*
>   * Tables to compute the ddd of year form icky dd/mm timecode. Viva la
> @@ -231,15 +233,27 @@
>  	 * the assert edge and do not enable the kernel hardpps.
>  	 */
>  	if (time_pps_create(fd, &up->handle) < 0) {
> -		up->handle = 0;
> -		msyslog(LOG_ERR,
> -		    "refclock_nmea: time_pps_create failed: %m");
> -		return (1);
> +		/* Try the alternare PPS device */
> +                (void) sprintf(device, DEVICEPPS, unit);
> +		msyslog(LOG_ERR, "refclock_nmea: try alternate PPS device %s", device);

Maybe you should do as in msyslog() below:

+             msyslog(LOG_ERR, "refclock_nmea: try alternate PPS device \"%s\"", device);

> +                fd = open(device, O_RDWR);
> +                if (fd < 0)
> +                	goto pps_error;
> +		if (time_pps_create(fd, &up->handle) < 0)
> +               		goto pps_error;
>  	}
> +	else (void) sprintf(device, DEVICE, unit); /* just rebuild device's name */
> +	msyslog(LOG_INFO, "refclock_nmea: found PPS source \"%s\"", device);
>  	return(nmea_ppsapi(peer, 0, 0));
>  #else
>  	return (1);
>  #endif /* HAVE_PPSAPI */
> +
> +pps_error:
> +	/* No luck, no PPS unit available! */
> +	up->handle = -1;
> +	msyslog(LOG_ERR, "refclock_nmea: no PPS devices found at " DEVICE " nor " DEVICEPPS ": %m", unit, unit);
> +	return (1);
>  }
>  
>  /*
> @@ -257,8 +271,7 @@
>  	pp = peer->procptr;
>  	up = (struct nmeaunit *)pp->unitptr;
>  #ifdef HAVE_PPSAPI
> -	if (up->handle != 0)
> -		time_pps_destroy(up->handle);
> +	time_pps_destroy(up->handle);
>  #endif /* HAVE_PPSAPI */
>  	io_closeclock(&pp->io);
>  	free(up);
> @@ -366,7 +379,7 @@
>  	/*
>  	 * Convert the timespec nanoseconds field to ntp l_fp units.
>  	 */ 
> -	if (up->handle == 0)
> +	if (up->handle == -1)
>  		return (0);
>  	timeout.tv_sec = 0;
>  	timeout.tv_nsec = 0;

>From LinuxPPS's point of view the patch is correct. Good job! :)

Ciao,

Rodolfo

-- 

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Linux Device Driver                             giometti at gnudd.com
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