/**

 * @file phc.c

 * @note Copyright (C) 2011 Richard Cochran <richardcochran@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License along

 * with this program; if not, write to the Free Software Foundation, Inc.,

 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include <stdio.h>

#include <sys/ioctl.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <unistd.h>

#include <linux/ptp_clock.h>

#include "phc.h"

/*

 * On 32 bit platforms, the PHC driver's maximum adjustment (type

 * 'int' in units of ppb) can overflow the timex.freq field (type

 * 'long'). So in this case we clamp the maximum to the largest

 * possible adjustment that fits into a 32 bit long.

 */

#define BITS_PER_LONG	(sizeof(long)*8)

#define MAX_PPB_32	32767999	/* 2^31 - 1 / 65.536 */

static int phc_get_caps(clockid_t clkid, struct ptp_clock_caps *caps);

clockid_t phc_open(char *phc)

{

	clockid_t clkid;

	struct ptp_clock_caps caps;

	int fd = open(phc, O_RDWR);

	if (fd < 0)

		return CLOCK_INVALID;

	clkid = FD_TO_CLOCKID(fd);

	/* check if clkid is valid */

	if (phc_get_caps(clkid, &caps)) {

		close(fd);

		return CLOCK_INVALID;

	}

	return clkid;

}

void phc_close(clockid_t clkid)

{

	if (clkid == CLOCK_INVALID)

		return;

	close(CLOCKID_TO_FD(clkid));

}

static int phc_get_caps(clockid_t clkid, struct ptp_clock_caps *caps)

{

	int fd = CLOCKID_TO_FD(clkid), err;

	err = ioctl(fd, PTP_CLOCK_GETCAPS, caps);

	if (err)

		perror("PTP_CLOCK_GETCAPS");

	return err;

}

int phc_max_adj(clockid_t clkid)

{

	int max;

	struct ptp_clock_caps caps;

	if (phc_get_caps(clkid, &caps))

		return 0;

	max = caps.max_adj;

	if (BITS_PER_LONG == 32 && max > MAX_PPB_32)

		max = MAX_PPB_32;

	return max;

}

int phc_has_pps(clockid_t clkid)

{

	struct ptp_clock_caps caps;

	if (phc_get_caps(clkid, &caps))

		return 0;

	return caps.pps;

}