text: /*
   * kernel API
   *
   *
   * Copyright (C) 2005-2009   Rodolfo Giometti <giometti@linux.it>
   *
   *   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., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/time.h>
  #include <linux/timex.h>
  #include <linux/spinlock.h>
  #include <linux/fs.h>
  #include <linux/pps_kernel.h>
  #include <linux/slab.h>
  
  #include "kc.h"
  
  /*
   * Local functions
   */
  
  static void pps_add_offset(struct pps_ktime *ts, struct pps_ktime *offset)
  {
  	ts->nsec += offset->nsec;
  	while (ts->nsec >= NSEC_PER_SEC) {
  		ts->nsec -= NSEC_PER_SEC;
  		ts->sec++;
  	}
  	while (ts->nsec < 0) {
  		ts->nsec += NSEC_PER_SEC;
  		ts->sec--;
  	}
  	ts->sec += offset->sec;
  }
  
  static void pps_echo_client_default(struct pps_device *pps, int event,
  		void *data)
  {
  	dev_info(pps->dev, "echo %s %s\n",
  		event & PPS_CAPTUREASSERT ? "assert" : "",
  		event & PPS_CAPTURECLEAR ? "clear" : "");
  }
  
  /*
   * Exported functions
   */
  
  /* pps_register_source - add a PPS source in the system
   * @info: the PPS info struct
   * @default_params: the default PPS parameters of the new source
   *
   * This function is used to add a new PPS source in the system. The new
   * source is described by info's fields and it will have, as default PPS
   * parameters, the ones specified into default_params.
   *
   * The function returns, in case of success, the PPS device. Otherwise NULL.
   */
  
  struct pps_device *pps_register_source(struct pps_source_info *info,
  		int default_params)
  {
  	struct pps_device *pps;
  	int err;
  
  	/* Sanity checks */
  	if ((info->mode & default_params) != default_params) {
  		pr_err("%s: unsupported default parameters\n",
  					info->name);
  		err = -EINVAL;
  		goto pps_register_source_exit;
  	}
  	if ((info->mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
  		pr_err("%s: unspecified time format\n",
  					info->name);
  		err = -EINVAL;
  		goto pps_register_source_exit;
  	}
  
  	/* Allocate memory for the new PPS source struct */
  	pps = kzalloc(sizeof(struct pps_device), GFP_KERNEL);
  	if (pps == NULL) {
  		err = -ENOMEM;
  		goto pps_register_source_exit;
  	}
  
  	/* These initializations must be done before calling idr_alloc()
  	 * in order to avoid reces into pps_event().
  	 */
  	pps->params.api_version = PPS_API_VERS;
  	pps->params.mode = default_params;
  	pps->info = *info;
  
  	/* check for default echo function */
  	if ((pps->info.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)) &&
  			pps->info.echo == NULL)
  		pps->info.echo = pps_echo_client_default;
  
  	init_waitqueue_head(&pps->queue);
  	spin_lock_init(&pps->lock);
  
  	/* Create the char device */
  	err = pps_register_cdev(pps);
  	if (err < 0) {
  		pr_err("%s: unable to create char device\n",
  					info->name);
  		goto kfree_pps;
  	}
  
  	dev_info(pps->dev, "new PPS source %s\n", info->name);
  
  	return pps;
  
  kfree_pps:
  	kfree(pps);
  
  pps_register_source_exit:
  	pr_err("%s: unable to register source\n", info->name);
  
  	return NULL;
  }
  EXPORT_SYMBOL(pps_register_source);
  
  /* pps_unregister_source - remove a PPS source from the system
   * @pps: the PPS source
   *
   * This function is used to remove a previously registered PPS source from
   * the system.
   */
  
  void pps_unregister_source(struct pps_device *pps)
  {
  	pps_kc_remove(pps);
  	pps_unregister_cdev(pps);
  
  	/* don't have to kfree(pps) here because it will be done on
  	 * device destruction */
  }
  EXPORT_SYMBOL(pps_unregister_source);
  
  /* pps_event - register a PPS event into the system
   * @pps: the PPS device
   * @ts: the event timestamp
   * @event: the event type
   * @data: userdef pointer
   *
   * This function is used by each PPS client in order to register a new
   * PPS event into the system (it's usually called inside an IRQ handler).
   *
   * If an echo function is associated with the PPS device it will be called
   * as:
   *	pps->info.echo(pps, event, data);
   */
  void pps_event(struct pps_device *pps, struct pps_event_time *ts, int event,
  		void *data)
  {
  	unsigned long flags;
  	int captured = 0;
  	struct pps_ktime ts_real = { .sec = 0, .nsec = 0, .flags = 0 };
  
  	/* check event type */
  	BUG_ON((event & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR)) == 0);
  
  	dev_dbg(pps->dev, "PPS event at %ld.%09ld\n",
  			ts->ts_real.tv_sec, ts->ts_real.tv_nsec);
  
  	timespec_to_pps_ktime(&ts_real, ts->ts_real);
  
  	spin_lock_irqsave(&pps->lock, flags);
  
  	/* Must call the echo function? */
  	if ((pps->params.mode & (PPS_ECHOASSERT | PPS_ECHOCLEAR)))
  		pps->info.echo(pps, event, data);
  
  	/* Check the event */
  	pps->current_mode = pps->params.mode;
  	if (event & pps->params.mode & PPS_CAPTUREASSERT) {
  		/* We have to add an offset? */
  		if (pps->params.mode & PPS_OFFSETASSERT)
  			pps_add_offset(&ts_real,
  					&pps->params.assert_off_tu);
  
  		/* Save the time stamp */
  		pps->assert_tu = ts_real;
  		pps->assert_sequence++;
  		dev_dbg(pps->dev, "capture assert seq #%u\n",
  			pps->assert_sequence);
  
  		captured = ~0;
  	}
  	if (event & pps->params.mode & PPS_CAPTURECLEAR) {
  		/* We have to add an offset? */
  		if (pps->params.mode & PPS_OFFSETCLEAR)
  			pps_add_offset(&ts_real,
  					&pps->params.clear_off_tu);
  
  		/* Save the time stamp */
  		pps->clear_tu = ts_real;
  		pps->clear_sequence++;
  		dev_dbg(pps->dev, "capture clear seq #%u\n",
  			pps->clear_sequence);
  
  		captured = ~0;
  	}
  
  	pps_kc_event(pps, ts, event);
  
  	/* Wake up if captured something */
  	if (captured) {
  		pps->last_ev++;
  		wake_up_interruptible_all(&pps->queue);
  
  		kill_fasync(&pps->async_queue, SIGIO, POLL_IN);
  	}
  
  	spin_unlock_irqrestore(&pps->lock, flags);
  }
  EXPORT_SYMBOL(pps_event);
  