/*
   * PPS core file
   *
   *
   * 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/uaccess.h>
  #include <linux/idr.h>

  #include <linux/mutex.h>

  #include <linux/cdev.h>
  #include <linux/poll.h>
  #include <linux/pps_kernel.h>

  #include <linux/slab.h>

  #include "kc.h"

  /*
   * Local variables
   */
  
  static dev_t pps_devt;
  static struct class *pps_class;

  static DEFINE_MUTEX(pps_idr_lock);

  static DEFINE_IDR(pps_idr);

  /*
   * Char device methods
   */
  
  static unsigned int pps_cdev_poll(struct file *file, poll_table *wait)
  {
  	struct pps_device *pps = file->private_data;
  
  	poll_wait(file, &pps->queue, wait);
  
  	return POLLIN | POLLRDNORM;
  }
  
  static int pps_cdev_fasync(int fd, struct file *file, int on)
  {
  	struct pps_device *pps = file->private_data;
  	return fasync_helper(fd, file, on, &pps->async_queue);
  }
  
  static long pps_cdev_ioctl(struct file *file,
  		unsigned int cmd, unsigned long arg)
  {
  	struct pps_device *pps = file->private_data;
  	struct pps_kparams params;

  	void __user *uarg = (void __user *) arg;
  	int __user *iuarg = (int __user *) arg;
  	int err;
  
  	switch (cmd) {
  	case PPS_GETPARAMS:

  		dev_dbg(pps->dev, "PPS_GETPARAMS
  ");

  		spin_lock_irq(&pps->lock);
  
  		/* Get the current parameters */
  		params = pps->params;
  
  		spin_unlock_irq(&pps->lock);
  
  		err = copy_to_user(uarg, &params, sizeof(struct pps_kparams));

  		if (err)
  			return -EFAULT;
  
  		break;
  
  	case PPS_SETPARAMS:

  		dev_dbg(pps->dev, "PPS_SETPARAMS
  ");

  
  		/* Check the capabilities */
  		if (!capable(CAP_SYS_TIME))
  			return -EPERM;
  
  		err = copy_from_user(&params, uarg, sizeof(struct pps_kparams));
  		if (err)
  			return -EFAULT;
  		if (!(params.mode & (PPS_CAPTUREASSERT | PPS_CAPTURECLEAR))) {

  			dev_dbg(pps->dev, "capture mode unspecified (%x)
  ",

  								params.mode);
  			return -EINVAL;
  		}
  
  		/* Check for supported capabilities */
  		if ((params.mode & ~pps->info.mode) != 0) {

  			dev_dbg(pps->dev, "unsupported capabilities (%x)
  ",

  								params.mode);
  			return -EINVAL;
  		}
  
  		spin_lock_irq(&pps->lock);
  
  		/* Save the new parameters */
  		pps->params = params;
  
  		/* Restore the read only parameters */
  		if ((params.mode & (PPS_TSFMT_TSPEC | PPS_TSFMT_NTPFP)) == 0) {
  			/* section 3.3 of RFC 2783 interpreted */

  			dev_dbg(pps->dev, "time format unspecified (%x)
  ",

  								params.mode);
  			pps->params.mode |= PPS_TSFMT_TSPEC;
  		}
  		if (pps->info.mode & PPS_CANWAIT)
  			pps->params.mode |= PPS_CANWAIT;
  		pps->params.api_version = PPS_API_VERS;
  
  		spin_unlock_irq(&pps->lock);
  
  		break;
  
  	case PPS_GETCAP:

  		dev_dbg(pps->dev, "PPS_GETCAP
  ");

  
  		err = put_user(pps->info.mode, iuarg);
  		if (err)
  			return -EFAULT;
  
  		break;

  	case PPS_FETCH: {
  		struct pps_fdata fdata;

  		unsigned int ev;

  		dev_dbg(pps->dev, "PPS_FETCH
  ");

  
  		err = copy_from_user(&fdata, uarg, sizeof(struct pps_fdata));
  		if (err)
  			return -EFAULT;

  		ev = pps->last_ev;

  
  		/* Manage the timeout */
  		if (fdata.timeout.flags & PPS_TIME_INVALID)

  			err = wait_event_interruptible(pps->queue,
  					ev != pps->last_ev);

  		else {

  			unsigned long ticks;

  			dev_dbg(pps->dev, "timeout %lld.%09d
  ",

  					(long long) fdata.timeout.sec,
  					fdata.timeout.nsec);
  			ticks = fdata.timeout.sec * HZ;
  			ticks += fdata.timeout.nsec / (NSEC_PER_SEC / HZ);
  
  			if (ticks != 0) {
  				err = wait_event_interruptible_timeout(

  						pps->queue,
  						ev != pps->last_ev,
  						ticks);

  				if (err == 0)
  					return -ETIMEDOUT;
  			}
  		}
  
  		/* Check for pending signals */
  		if (err == -ERESTARTSYS) {

  			dev_dbg(pps->dev, "pending signal caught
  ");

  			return -EINTR;
  		}
  
  		/* Return the fetched timestamp */
  		spin_lock_irq(&pps->lock);
  
  		fdata.info.assert_sequence = pps->assert_sequence;
  		fdata.info.clear_sequence = pps->clear_sequence;
  		fdata.info.assert_tu = pps->assert_tu;
  		fdata.info.clear_tu = pps->clear_tu;
  		fdata.info.current_mode = pps->current_mode;
  
  		spin_unlock_irq(&pps->lock);
  
  		err = copy_to_user(uarg, &fdata, sizeof(struct pps_fdata));
  		if (err)
  			return -EFAULT;
  
  		break;

  	}

  	case PPS_KC_BIND: {
  		struct pps_bind_args bind_args;
  
  		dev_dbg(pps->dev, "PPS_KC_BIND
  ");
  
  		/* Check the capabilities */
  		if (!capable(CAP_SYS_TIME))
  			return -EPERM;
  
  		if (copy_from_user(&bind_args, uarg,
  					sizeof(struct pps_bind_args)))
  			return -EFAULT;
  
  		/* Check for supported capabilities */
  		if ((bind_args.edge & ~pps->info.mode) != 0) {
  			dev_err(pps->dev, "unsupported capabilities (%x)
  ",
  					bind_args.edge);
  			return -EINVAL;
  		}
  
  		/* Validate parameters roughly */
  		if (bind_args.tsformat != PPS_TSFMT_TSPEC ||
  				(bind_args.edge & ~PPS_CAPTUREBOTH) != 0 ||
  				bind_args.consumer != PPS_KC_HARDPPS) {
  			dev_err(pps->dev, "invalid kernel consumer bind"
  					" parameters (%x)
  ", bind_args.edge);
  			return -EINVAL;
  		}
  
  		err = pps_kc_bind(pps, &bind_args);
  		if (err < 0)
  			return err;
  
  		break;
  	}

  	default:
  		return -ENOTTY;

  	}
  
  	return 0;
  }
  
  static int pps_cdev_open(struct inode *inode, struct file *file)
  {
  	struct pps_device *pps = container_of(inode->i_cdev,
  						struct pps_device, cdev);

  	file->private_data = pps;
  
  	return 0;
  }
  
  static int pps_cdev_release(struct inode *inode, struct file *file)
  {

  	return 0;
  }
  
  /*
   * Char device stuff
   */
  
  static const struct file_operations pps_cdev_fops = {
  	.owner		= THIS_MODULE,
  	.llseek		= no_llseek,
  	.poll		= pps_cdev_poll,
  	.fasync		= pps_cdev_fasync,
  	.unlocked_ioctl	= pps_cdev_ioctl,
  	.open		= pps_cdev_open,
  	.release	= pps_cdev_release,
  };

  static void pps_device_destruct(struct device *dev)
  {
  	struct pps_device *pps = dev_get_drvdata(dev);
  
  	/* release id here to protect others from using it while it's
  	 * still in use */

  	mutex_lock(&pps_idr_lock);

  	idr_remove(&pps_idr, pps->id);

  	mutex_unlock(&pps_idr_lock);

  
  	kfree(dev);
  	kfree(pps);
  }

  int pps_register_cdev(struct pps_device *pps)
  {
  	int err;

  	dev_t devt;

  	mutex_lock(&pps_idr_lock);

  	/* Get new ID for the new PPS source */

  	if (idr_pre_get(&pps_idr, GFP_KERNEL) == 0) {
  		mutex_unlock(&pps_idr_lock);

  		return -ENOMEM;

  	}

  
  	/* Now really allocate the PPS source.
  	 * After idr_get_new() calling the new source will be freely available
  	 * into the kernel.
  	 */

  	err = idr_get_new(&pps_idr, pps, &pps->id);

  	mutex_unlock(&pps_idr_lock);

  
  	if (err < 0)
  		return err;
  
  	pps->id &= MAX_ID_MASK;
  	if (pps->id >= PPS_MAX_SOURCES) {
  		pr_err("%s: too many PPS sources in the system
  ",
  					pps->info.name);
  		err = -EBUSY;
  		goto free_idr;
  	}

  	devt = MKDEV(MAJOR(pps_devt), pps->id);

  	cdev_init(&pps->cdev, &pps_cdev_fops);
  	pps->cdev.owner = pps->info.owner;

  	err = cdev_add(&pps->cdev, devt, 1);

  	if (err) {

  		pr_err("%s: failed to add char device %d:%d
  ",

  				pps->info.name, MAJOR(pps_devt), pps->id);

  		goto free_idr;

  	}

  	pps->dev = device_create(pps_class, pps->info.dev, devt, pps,

  							"pps%d", pps->id);

  	if (IS_ERR(pps->dev))

  		goto del_cdev;

  	pps->dev->release = pps_device_destruct;

  	pr_debug("source %s got cdev (%d:%d)
  ", pps->info.name,
  			MAJOR(pps_devt), pps->id);
  
  	return 0;
  
  del_cdev:
  	cdev_del(&pps->cdev);

  free_idr:

  	mutex_lock(&pps_idr_lock);

  	idr_remove(&pps_idr, pps->id);

  	mutex_unlock(&pps_idr_lock);

  	return err;
  }
  
  void pps_unregister_cdev(struct pps_device *pps)
  {

  	device_destroy(pps_class, pps->dev->devt);

  	cdev_del(&pps->cdev);
  }
  
  /*
   * Module stuff
   */
  
  static void __exit pps_exit(void)
  {
  	class_destroy(pps_class);
  	unregister_chrdev_region(pps_devt, PPS_MAX_SOURCES);
  }
  
  static int __init pps_init(void)
  {
  	int err;
  
  	pps_class = class_create(THIS_MODULE, "pps");
  	if (!pps_class) {

  		pr_err("failed to allocate class
  ");

  		return -ENOMEM;
  	}
  	pps_class->dev_attrs = pps_attrs;
  
  	err = alloc_chrdev_region(&pps_devt, 0, PPS_MAX_SOURCES, "pps");
  	if (err < 0) {

  		pr_err("failed to allocate char device region
  ");

  		goto remove_class;
  	}
  
  	pr_info("LinuxPPS API ver. %d registered
  ", PPS_API_VERS);
  	pr_info("Software ver. %s - Copyright 2005-2007 Rodolfo Giometti "
  		"<giometti@linux.it>
  ", PPS_VERSION);
  
  	return 0;
  
  remove_class:
  	class_destroy(pps_class);
  
  	return err;
  }
  
  subsys_initcall(pps_init);
  module_exit(pps_exit);
  
  MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
  MODULE_DESCRIPTION("LinuxPPS support (RFC 2783) - ver. " PPS_VERSION);
  MODULE_LICENSE("GPL");