/*
   * PTP 1588 clock support
   *
   * Copyright (C) 2010 OMICRON electronics GmbH
   *
   *  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.
   */
  #include <linux/idr.h>
  #include <linux/device.h>
  #include <linux/err.h>
  #include <linux/init.h>
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/posix-clock.h>
  #include <linux/pps_kernel.h>
  #include <linux/slab.h>
  #include <linux/syscalls.h>
  #include <linux/uaccess.h>
  
  #include "ptp_private.h"
  
  #define PTP_MAX_ALARMS 4
  #define PTP_PPS_DEFAULTS (PPS_CAPTUREASSERT | PPS_OFFSETASSERT)
  #define PTP_PPS_EVENT PPS_CAPTUREASSERT
  #define PTP_PPS_MODE (PTP_PPS_DEFAULTS | PPS_CANWAIT | PPS_TSFMT_TSPEC)
  
  /* private globals */
  
  static dev_t ptp_devt;
  static struct class *ptp_class;
  
  static DEFINE_IDA(ptp_clocks_map);
  
  /* time stamp event queue operations */
  
  static inline int queue_free(struct timestamp_event_queue *q)
  {
  	return PTP_MAX_TIMESTAMPS - queue_cnt(q) - 1;
  }
  
  static void enqueue_external_timestamp(struct timestamp_event_queue *queue,
  				       struct ptp_clock_event *src)
  {
  	struct ptp_extts_event *dst;
  	unsigned long flags;
  	s64 seconds;
  	u32 remainder;
  
  	seconds = div_u64_rem(src->timestamp, 1000000000, &remainder);
  
  	spin_lock_irqsave(&queue->lock, flags);
  
  	dst = &queue->buf[queue->tail];
  	dst->index = src->index;
  	dst->t.sec = seconds;
  	dst->t.nsec = remainder;
  
  	if (!queue_free(queue))
  		queue->head = (queue->head + 1) % PTP_MAX_TIMESTAMPS;
  
  	queue->tail = (queue->tail + 1) % PTP_MAX_TIMESTAMPS;
  
  	spin_unlock_irqrestore(&queue->lock, flags);
  }
  
  static s32 scaled_ppm_to_ppb(long ppm)
  {
  	/*
  	 * The 'freq' field in the 'struct timex' is in parts per
  	 * million, but with a 16 bit binary fractional field.
  	 *
  	 * We want to calculate
  	 *
  	 *    ppb = scaled_ppm * 1000 / 2^16
  	 *
  	 * which simplifies to
  	 *
  	 *    ppb = scaled_ppm * 125 / 2^13
  	 */
  	s64 ppb = 1 + ppm;
  	ppb *= 125;
  	ppb >>= 13;
  	return (s32) ppb;
  }
  
  /* posix clock implementation */
  
  static int ptp_clock_getres(struct posix_clock *pc, struct timespec *tp)
  {
  	tp->tv_sec = 0;
  	tp->tv_nsec = 1;
  	return 0;
  }
  
  static int ptp_clock_settime(struct posix_clock *pc, const struct timespec *tp)
  {
  	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
  	return ptp->info->settime(ptp->info, tp);
  }
  
  static int ptp_clock_gettime(struct posix_clock *pc, struct timespec *tp)
  {
  	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
  	return ptp->info->gettime(ptp->info, tp);
  }
  
  static int ptp_clock_adjtime(struct posix_clock *pc, struct timex *tx)
  {
  	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
  	struct ptp_clock_info *ops;
  	int err = -EOPNOTSUPP;
  
  	ops = ptp->info;
  
  	if (tx->modes & ADJ_SETOFFSET) {
  		struct timespec ts;
  		ktime_t kt;
  		s64 delta;
  
  		ts.tv_sec  = tx->time.tv_sec;
  		ts.tv_nsec = tx->time.tv_usec;
  
  		if (!(tx->modes & ADJ_NANO))
  			ts.tv_nsec *= 1000;
  
  		if ((unsigned long) ts.tv_nsec >= NSEC_PER_SEC)
  			return -EINVAL;
  
  		kt = timespec_to_ktime(ts);
  		delta = ktime_to_ns(kt);
  		err = ops->adjtime(ops, delta);
  	} else if (tx->modes & ADJ_FREQUENCY) {
  		err = ops->adjfreq(ops, scaled_ppm_to_ppb(tx->freq));
  		ptp->dialed_frequency = tx->freq;
  	} else if (tx->modes == 0) {
  		tx->freq = ptp->dialed_frequency;
  		err = 0;
  	}
  
  	return err;
  }
  
  static struct posix_clock_operations ptp_clock_ops = {
  	.owner		= THIS_MODULE,
  	.clock_adjtime	= ptp_clock_adjtime,
  	.clock_gettime	= ptp_clock_gettime,
  	.clock_getres	= ptp_clock_getres,
  	.clock_settime	= ptp_clock_settime,
  	.ioctl		= ptp_ioctl,
  	.open		= ptp_open,
  	.poll		= ptp_poll,
  	.read		= ptp_read,
  };
  
  static void delete_ptp_clock(struct posix_clock *pc)
  {
  	struct ptp_clock *ptp = container_of(pc, struct ptp_clock, clock);
  
  	mutex_destroy(&ptp->tsevq_mux);
  	mutex_destroy(&ptp->pincfg_mux);
  	ida_simple_remove(&ptp_clocks_map, ptp->index);
  	kfree(ptp);
  }
  
  /* public interface */
  
  struct ptp_clock *ptp_clock_register(struct ptp_clock_info *info,
  				     struct device *parent)
  {
  	struct ptp_clock *ptp;
  	int err = 0, index, major = MAJOR(ptp_devt);
  
  	if (info->n_alarm > PTP_MAX_ALARMS)
  		return ERR_PTR(-EINVAL);
  
  	/* Initialize a clock structure. */
  	err = -ENOMEM;
  	ptp = kzalloc(sizeof(struct ptp_clock), GFP_KERNEL);
  	if (ptp == NULL)
  		goto no_memory;
  
  	index = ida_simple_get(&ptp_clocks_map, 0, MINORMASK + 1, GFP_KERNEL);
  	if (index < 0) {
  		err = index;
  		goto no_slot;
  	}
  
  	ptp->clock.ops = ptp_clock_ops;
  	ptp->clock.release = delete_ptp_clock;
  	ptp->info = info;
  	ptp->devid = MKDEV(major, index);
  	ptp->index = index;
  	spin_lock_init(&ptp->tsevq.lock);
  	mutex_init(&ptp->tsevq_mux);
  	mutex_init(&ptp->pincfg_mux);
  	init_waitqueue_head(&ptp->tsev_wq);
  
  	/* Create a new device in our class. */
  	ptp->dev = device_create(ptp_class, parent, ptp->devid, ptp,
  				 "ptp%d", ptp->index);
  	if (IS_ERR(ptp->dev))
  		goto no_device;
  
  	dev_set_drvdata(ptp->dev, ptp);
  
  	err = ptp_populate_sysfs(ptp);
  	if (err)
  		goto no_sysfs;
  
  	/* Register a new PPS source. */
  	if (info->pps) {
  		struct pps_source_info pps;
  		memset(&pps, 0, sizeof(pps));
  		snprintf(pps.name, PPS_MAX_NAME_LEN, "ptp%d", index);
  		pps.mode = PTP_PPS_MODE;
  		pps.owner = info->owner;
  		ptp->pps_source = pps_register_source(&pps, PTP_PPS_DEFAULTS);
  		if (!ptp->pps_source) {
  			pr_err("failed to register pps source
  ");
  			goto no_pps;
  		}
  	}
  
  	/* Create a posix clock. */
  	err = posix_clock_register(&ptp->clock, ptp->devid);
  	if (err) {
  		pr_err("failed to create posix clock
  ");
  		goto no_clock;
  	}
  
  	return ptp;
  
  no_clock:
  	if (ptp->pps_source)
  		pps_unregister_source(ptp->pps_source);
  no_pps:
  	ptp_cleanup_sysfs(ptp);
  no_sysfs:
  	device_destroy(ptp_class, ptp->devid);
  no_device:
  	mutex_destroy(&ptp->tsevq_mux);
  	mutex_destroy(&ptp->pincfg_mux);
  no_slot:
  	kfree(ptp);
  no_memory:
  	return ERR_PTR(err);
  }
  EXPORT_SYMBOL(ptp_clock_register);
  
  int ptp_clock_unregister(struct ptp_clock *ptp)
  {
  	ptp->defunct = 1;
  	wake_up_interruptible(&ptp->tsev_wq);
  
  	/* Release the clock's resources. */
  	if (ptp->pps_source)
  		pps_unregister_source(ptp->pps_source);
  	ptp_cleanup_sysfs(ptp);
  	device_destroy(ptp_class, ptp->devid);
  
  	posix_clock_unregister(&ptp->clock);
  	return 0;
  }
  EXPORT_SYMBOL(ptp_clock_unregister);
  
  void ptp_clock_event(struct ptp_clock *ptp, struct ptp_clock_event *event)
  {
  	struct pps_event_time evt;
  
  	switch (event->type) {
  
  	case PTP_CLOCK_ALARM:
  		break;
  
  	case PTP_CLOCK_EXTTS:
  		enqueue_external_timestamp(&ptp->tsevq, event);
  		wake_up_interruptible(&ptp->tsev_wq);
  		break;
  
  	case PTP_CLOCK_PPS:
  		pps_get_ts(&evt);
  		pps_event(ptp->pps_source, &evt, PTP_PPS_EVENT, NULL);
  		break;
  
  	case PTP_CLOCK_PPSUSR:
  		pps_event(ptp->pps_source, &event->pps_times,
  			  PTP_PPS_EVENT, NULL);
  		break;
  	}
  }
  EXPORT_SYMBOL(ptp_clock_event);
  
  int ptp_clock_index(struct ptp_clock *ptp)
  {
  	return ptp->index;
  }
  EXPORT_SYMBOL(ptp_clock_index);
  
  int ptp_find_pin(struct ptp_clock *ptp,
  		 enum ptp_pin_function func, unsigned int chan)
  {
  	struct ptp_pin_desc *pin = NULL;
  	int i;
  
  	mutex_lock(&ptp->pincfg_mux);
  	for (i = 0; i < ptp->info->n_pins; i++) {
  		if (ptp->info->pin_config[i].func == func &&
  		    ptp->info->pin_config[i].chan == chan) {
  			pin = &ptp->info->pin_config[i];
  			break;
  		}
  	}
  	mutex_unlock(&ptp->pincfg_mux);
  
  	return pin ? i : -1;
  }
  EXPORT_SYMBOL(ptp_find_pin);
  
  /* module operations */
  
  static void __exit ptp_exit(void)
  {
  	class_destroy(ptp_class);
  	unregister_chrdev_region(ptp_devt, MINORMASK + 1);
  	ida_destroy(&ptp_clocks_map);
  }
  
  static int __init ptp_init(void)
  {
  	int err;
  
  	ptp_class = class_create(THIS_MODULE, "ptp");
  	if (IS_ERR(ptp_class)) {
  		pr_err("ptp: failed to allocate class
  ");
  		return PTR_ERR(ptp_class);
  	}
  
  	err = alloc_chrdev_region(&ptp_devt, 0, MINORMASK + 1, "ptp");
  	if (err < 0) {
  		pr_err("ptp: failed to allocate device region
  ");
  		goto no_region;
  	}
  
  	ptp_class->dev_groups = ptp_groups;
  	pr_info("PTP clock support registered
  ");
  	return 0;
  
  no_region:
  	class_destroy(ptp_class);
  	return err;
  }
  
  subsys_initcall(ptp_init);
  module_exit(ptp_exit);
  
  MODULE_AUTHOR("Richard Cochran <richardcochran@gmail.com>");
  MODULE_DESCRIPTION("PTP clocks support");
  MODULE_LICENSE("GPL");