/*
   * 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
  ",
  		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
  ",

  					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
  ",

  					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_get_new()
  	 * 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
  ",

  					info->name);

  		goto kfree_pps;

  	}

  	dev_info(pps->dev, "new PPS source %s
  ", info->name);

  	return pps;

  kfree_pps:
  	kfree(pps);
  
  pps_register_source_exit:

  	pr_err("%s: unable to register source
  ", 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
  ",
  			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
  ",
  			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
  ",
  			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);