[LinuxPPS] Re: [Bug 610] Generic NMEA GPS Receiver driver w/ PPS expects PPS after NMEA data

[Rodolfo Giometti]

On Mon, Oct 29, 2007 at 05:26:58PM +0100, Udo van den Heuvel wrote:
> Rodolfo Giometti wrote:
> > In this situation you should do something like:
> 
> Like the attached patch?
> 
> Is this better?

Yes... but maybe you can do..

> --- org.ntp-4.2.4p2/ntpd/refclock_nmea.c	2006-06-06 22:16:53.000000000 +0200
> +++ ntp-4.2.4p2/ntpd/refclock_nmea.c	2007-10-29 17:25:57.000000000 +0100
> @@ -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/gpspps%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
> @@ -230,13 +232,32 @@
>  	 * Start the PPSAPI interface if it is there. Default to use
>  	 * 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);
> -	}
> +	msyslog(LOG_ERR, "refclock_nmea: found GPS source \"%s\"", device);
> +        (void) sprintf(device, DEVICEPPS, unit);
> +        fd = open(device, O_RDWR);
> +        if (fd < 0) { 			/* no /dev/gpspps0 */
> +		goto try_main_device; 	/* Try /dev/gps device for PPS */
> +	} else {  			/* /dev/gpspps0 exists */
> +		msyslog(LOG_ERR, "refclock_nmea: try \"%s\" for PPS", device);
> +		if (time_pps_create(fd, &up->handle) < 0)  
> +			goto try_main_device;   /* Try /dev/gps for PPS */
> +		else goto found_source; /* PPS on /dev/gpspps0 */
> +	}

You don't need "else" clause here. You can do:

+        fd = open(device, O_RDWR);
+        if (fd < 0)                     /* no alternate device... */
+                goto try_main_device;   /* let's try main device for PPS */
+
+        /* Alternate device exists! */
+        msyslog(LOG_ERR, "refclock_nmea: try alternate PPS device \"%s\" for PPS", device);
+        if (time_pps_create(fd, &up->handle) < 0)
+                goto try_main_device;   /* No way... try main device for PPS */
+
+        msyslog(LOG_INFO, "refclock_nmea: found PPS source \"%s\" (alternate)", device);
+        return nmea_ppsapi(peer, 0, 0);
+
+try_main_device:
+        (void) sprintf(device, DEVICE, unit);
+	 msyslog(LOG_ERR, "refclock_nmea: try GPS device \"%s\" for PPS", device);
+	 if (time_pps_create(pp->io.fd, &up->handle) < 0)
+                goto pps_error;
+
+	 msyslog(LOG_INFO, "refclock_nmea: found PPS source \"%s\" (main)", device);
+  	 return nmea_ppsapi(peer, 0, 0);
+
> +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);

It seems more clear to me... but also your solution seem ok.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti at enneenne.com
Linux Device Driver                             giometti at gnudd.com
Embedded Systems                     		giometti at linux.it
UNIX programming                     phone:     +39 349 2432127