/* Industrial I/O event handling
   *
   * Copyright (c) 2008 Jonathan Cameron
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 as published by
   * the Free Software Foundation.
   *
   * Based on elements of hwmon and input subsystems.
   */
  
  #include <linux/anon_inodes.h>
  #include <linux/device.h>
  #include <linux/fs.h>
  #include <linux/kernel.h>
  #include <linux/kfifo.h>
  #include <linux/module.h>
  #include <linux/poll.h>
  #include <linux/sched.h>
  #include <linux/slab.h>
  #include <linux/uaccess.h>
  #include <linux/wait.h>
  #include <linux/iio/iio.h>
  #include "iio_core.h"
  #include <linux/iio/sysfs.h>
  #include <linux/iio/events.h>
  
  /**
   * struct iio_event_interface - chrdev interface for an event line
   * @wait:		wait queue to allow blocking reads of events
   * @det_events:		list of detected events
   * @dev_attr_list:	list of event interface sysfs attribute
   * @flags:		file operations related flags including busy flag.
   * @group:		event interface sysfs attribute group
   */
  struct iio_event_interface {
  	wait_queue_head_t	wait;
  	DECLARE_KFIFO(det_events, struct iio_event_data, 16);
  
  	struct list_head	dev_attr_list;
  	unsigned long		flags;
  	struct attribute_group	group;
  };
  
  /**
   * iio_push_event() - try to add event to the list for userspace reading
   * @indio_dev:		IIO device structure
   * @ev_code:		What event
   * @timestamp:		When the event occurred
   **/
  int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
  {
  	struct iio_event_interface *ev_int = indio_dev->event_interface;
  	struct iio_event_data ev;
  	unsigned long flags;
  	int copied;
  
  	/* Does anyone care? */
  	spin_lock_irqsave(&ev_int->wait.lock, flags);
  	if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  
  		ev.id = ev_code;
  		ev.timestamp = timestamp;
  
  		copied = kfifo_put(&ev_int->det_events, ev);
  		if (copied != 0)
  			wake_up_locked_poll(&ev_int->wait, POLLIN);
  	}
  	spin_unlock_irqrestore(&ev_int->wait.lock, flags);
  
  	return 0;
  }
  EXPORT_SYMBOL(iio_push_event);
  
  /**
   * iio_event_poll() - poll the event queue to find out if it has data
   */
  static unsigned int iio_event_poll(struct file *filep,
  			     struct poll_table_struct *wait)
  {
  	struct iio_dev *indio_dev = filep->private_data;
  	struct iio_event_interface *ev_int = indio_dev->event_interface;
  	unsigned int events = 0;
  
  	if (!indio_dev->info)
  		return -ENODEV;
  
  	poll_wait(filep, &ev_int->wait, wait);
  
  	spin_lock_irq(&ev_int->wait.lock);
  	if (!kfifo_is_empty(&ev_int->det_events))
  		events = POLLIN | POLLRDNORM;
  	spin_unlock_irq(&ev_int->wait.lock);
  
  	return events;
  }
  
  static ssize_t iio_event_chrdev_read(struct file *filep,
  				     char __user *buf,
  				     size_t count,
  				     loff_t *f_ps)
  {
  	struct iio_dev *indio_dev = filep->private_data;
  	struct iio_event_interface *ev_int = indio_dev->event_interface;
  	unsigned int copied;
  	int ret;
  
  	if (!indio_dev->info)
  		return -ENODEV;
  
  	if (count < sizeof(struct iio_event_data))
  		return -EINVAL;
  
  	spin_lock_irq(&ev_int->wait.lock);
  	if (kfifo_is_empty(&ev_int->det_events)) {
  		if (filep->f_flags & O_NONBLOCK) {
  			ret = -EAGAIN;
  			goto error_unlock;
  		}
  		/* Blocking on device; waiting for something to be there */
  		ret = wait_event_interruptible_locked_irq(ev_int->wait,
  					!kfifo_is_empty(&ev_int->det_events) ||
  					indio_dev->info == NULL);
  		if (ret)
  			goto error_unlock;
  		if (indio_dev->info == NULL) {
  			ret = -ENODEV;
  			goto error_unlock;
  		}
  		/* Single access device so no one else can get the data */
  	}
  
  	ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
  
  error_unlock:
  	spin_unlock_irq(&ev_int->wait.lock);
  
  	return ret ? ret : copied;
  }
  
  static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
  {
  	struct iio_dev *indio_dev = filep->private_data;
  	struct iio_event_interface *ev_int = indio_dev->event_interface;
  
  	spin_lock_irq(&ev_int->wait.lock);
  	__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
  	/*
  	 * In order to maintain a clean state for reopening,
  	 * clear out any awaiting events. The mask will prevent
  	 * any new __iio_push_event calls running.
  	 */
  	kfifo_reset_out(&ev_int->det_events);
  	spin_unlock_irq(&ev_int->wait.lock);
  
  	iio_device_put(indio_dev);
  
  	return 0;
  }
  
  static const struct file_operations iio_event_chrdev_fileops = {
  	.read =  iio_event_chrdev_read,
  	.poll =  iio_event_poll,
  	.release = iio_event_chrdev_release,
  	.owner = THIS_MODULE,
  	.llseek = noop_llseek,
  };
  
  int iio_event_getfd(struct iio_dev *indio_dev)
  {
  	struct iio_event_interface *ev_int = indio_dev->event_interface;
  	int fd;
  
  	if (ev_int == NULL)
  		return -ENODEV;
  
  	spin_lock_irq(&ev_int->wait.lock);
  	if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
  		spin_unlock_irq(&ev_int->wait.lock);
  		return -EBUSY;
  	}
  	spin_unlock_irq(&ev_int->wait.lock);
  	iio_device_get(indio_dev);
  
  	fd = anon_inode_getfd("iio:event", &iio_event_chrdev_fileops,
  				indio_dev, O_RDONLY | O_CLOEXEC);
  	if (fd < 0) {
  		spin_lock_irq(&ev_int->wait.lock);
  		__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
  		spin_unlock_irq(&ev_int->wait.lock);
  		iio_device_put(indio_dev);
  	}
  	return fd;
  }
  
  static const char * const iio_ev_type_text[] = {
  	[IIO_EV_TYPE_THRESH] = "thresh",
  	[IIO_EV_TYPE_MAG] = "mag",
  	[IIO_EV_TYPE_ROC] = "roc",
  	[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
  	[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
  };
  
  static const char * const iio_ev_dir_text[] = {
  	[IIO_EV_DIR_EITHER] = "either",
  	[IIO_EV_DIR_RISING] = "rising",
  	[IIO_EV_DIR_FALLING] = "falling"
  };
  
  static const char * const iio_ev_info_text[] = {
  	[IIO_EV_INFO_ENABLE] = "en",
  	[IIO_EV_INFO_VALUE] = "value",
  	[IIO_EV_INFO_HYSTERESIS] = "hysteresis",
  };
  
  static enum iio_event_direction iio_ev_attr_dir(struct iio_dev_attr *attr)
  {
  	return attr->c->event_spec[attr->address & 0xffff].dir;
  }
  
  static enum iio_event_type iio_ev_attr_type(struct iio_dev_attr *attr)
  {
  	return attr->c->event_spec[attr->address & 0xffff].type;
  }
  
  static enum iio_event_info iio_ev_attr_info(struct iio_dev_attr *attr)
  {
  	return (attr->address >> 16) & 0xffff;
  }
  
  static ssize_t iio_ev_state_store(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf,
  				  size_t len)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int ret;
  	bool val;
  
  	ret = strtobool(buf, &val);
  	if (ret < 0)
  		return ret;
  
  	ret = indio_dev->info->write_event_config(indio_dev,
  		this_attr->c, iio_ev_attr_type(this_attr),
  		iio_ev_attr_dir(this_attr), val);
  
  	return (ret < 0) ? ret : len;
  }
  
  static ssize_t iio_ev_state_show(struct device *dev,
  				 struct device_attribute *attr,
  				 char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int val;
  
  	val = indio_dev->info->read_event_config(indio_dev,
  		this_attr->c, iio_ev_attr_type(this_attr),
  		iio_ev_attr_dir(this_attr));
  	if (val < 0)
  		return val;
  	else
  		return sprintf(buf, "%d
  ", val);
  }
  
  static ssize_t iio_ev_value_show(struct device *dev,
  				 struct device_attribute *attr,
  				 char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int val, val2;
  	int ret;
  
  	ret = indio_dev->info->read_event_value(indio_dev,
  		this_attr->c, iio_ev_attr_type(this_attr),
  		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
  		&val, &val2);
  	if (ret < 0)
  		return ret;
  	return iio_format_value(buf, ret, val, val2);
  }
  
  static ssize_t iio_ev_value_store(struct device *dev,
  				  struct device_attribute *attr,
  				  const char *buf,
  				  size_t len)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	int val, val2;
  	int ret;
  
  	if (!indio_dev->info->write_event_value)
  		return -EINVAL;
  
  	ret = iio_str_to_fixpoint(buf, 100000, &val, &val2);
  	if (ret)
  		return ret;
  	ret = indio_dev->info->write_event_value(indio_dev,
  		this_attr->c, iio_ev_attr_type(this_attr),
  		iio_ev_attr_dir(this_attr), iio_ev_attr_info(this_attr),
  		val, val2);
  	if (ret < 0)
  		return ret;
  
  	return len;
  }
  
  static int iio_device_add_event(struct iio_dev *indio_dev,
  	const struct iio_chan_spec *chan, unsigned int spec_index,
  	enum iio_event_type type, enum iio_event_direction dir,
  	enum iio_shared_by shared_by, const unsigned long *mask)
  {
  	ssize_t (*show)(struct device *, struct device_attribute *, char *);
  	ssize_t (*store)(struct device *, struct device_attribute *,
  		const char *, size_t);
  	unsigned int attrcount = 0;
  	unsigned int i;
  	char *postfix;
  	int ret;
  
  	for_each_set_bit(i, mask, sizeof(*mask)) {
  		postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
  				iio_ev_type_text[type], iio_ev_dir_text[dir],
  				iio_ev_info_text[i]);
  		if (postfix == NULL)
  			return -ENOMEM;
  
  		if (i == IIO_EV_INFO_ENABLE) {
  			show = iio_ev_state_show;
  			store = iio_ev_state_store;
  		} else {
  			show = iio_ev_value_show;
  			store = iio_ev_value_store;
  		}
  
  		ret = __iio_add_chan_devattr(postfix, chan, show, store,
  			 (i << 16) | spec_index, shared_by, &indio_dev->dev,
  			&indio_dev->event_interface->dev_attr_list);
  		kfree(postfix);
  
  		if ((ret == -EBUSY) && (shared_by != IIO_SEPARATE))
  			continue;
  
  		if (ret)
  			return ret;
  
  		attrcount++;
  	}
  
  	return attrcount;
  }
  
  static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
  	struct iio_chan_spec const *chan)
  {
  	int ret = 0, i, attrcount = 0;
  	enum iio_event_direction dir;
  	enum iio_event_type type;
  
  	for (i = 0; i < chan->num_event_specs; i++) {
  		type = chan->event_spec[i].type;
  		dir = chan->event_spec[i].dir;
  
  		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
  			IIO_SEPARATE, &chan->event_spec[i].mask_separate);
  		if (ret < 0)
  			goto error_ret;
  		attrcount += ret;
  
  		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
  			IIO_SHARED_BY_TYPE,
  			&chan->event_spec[i].mask_shared_by_type);
  		if (ret < 0)
  			goto error_ret;
  		attrcount += ret;
  
  		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
  			IIO_SHARED_BY_DIR,
  			&chan->event_spec[i].mask_shared_by_dir);
  		if (ret < 0)
  			goto error_ret;
  		attrcount += ret;
  
  		ret = iio_device_add_event(indio_dev, chan, i, type, dir,
  			IIO_SHARED_BY_ALL,
  			&chan->event_spec[i].mask_shared_by_all);
  		if (ret < 0)
  			goto error_ret;
  		attrcount += ret;
  	}
  	ret = attrcount;
  error_ret:
  	return ret;
  }
  
  static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
  {
  	int j, ret, attrcount = 0;
  
  	/* Dynically created from the channels array */
  	for (j = 0; j < indio_dev->num_channels; j++) {
  		ret = iio_device_add_event_sysfs(indio_dev,
  						 &indio_dev->channels[j]);
  		if (ret < 0)
  			return ret;
  		attrcount += ret;
  	}
  	return attrcount;
  }
  
  static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
  {
  	int j;
  
  	for (j = 0; j < indio_dev->num_channels; j++) {
  		if (indio_dev->channels[j].num_event_specs != 0)
  			return true;
  	}
  	return false;
  }
  
  static void iio_setup_ev_int(struct iio_event_interface *ev_int)
  {
  	INIT_KFIFO(ev_int->det_events);
  	init_waitqueue_head(&ev_int->wait);
  }
  
  static const char *iio_event_group_name = "events";
  int iio_device_register_eventset(struct iio_dev *indio_dev)
  {
  	struct iio_dev_attr *p;
  	int ret = 0, attrcount_orig = 0, attrcount, attrn;
  	struct attribute **attr;
  
  	if (!(indio_dev->info->event_attrs ||
  	      iio_check_for_dynamic_events(indio_dev)))
  		return 0;
  
  	indio_dev->event_interface =
  		kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
  	if (indio_dev->event_interface == NULL) {
  		ret = -ENOMEM;
  		goto error_ret;
  	}
  
  	INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
  
  	iio_setup_ev_int(indio_dev->event_interface);
  	if (indio_dev->info->event_attrs != NULL) {
  		attr = indio_dev->info->event_attrs->attrs;
  		while (*attr++ != NULL)
  			attrcount_orig++;
  	}
  	attrcount = attrcount_orig;
  	if (indio_dev->channels) {
  		ret = __iio_add_event_config_attrs(indio_dev);
  		if (ret < 0)
  			goto error_free_setup_event_lines;
  		attrcount += ret;
  	}
  
  	indio_dev->event_interface->group.name = iio_event_group_name;
  	indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
  							  sizeof(indio_dev->event_interface->group.attrs[0]),
  							  GFP_KERNEL);
  	if (indio_dev->event_interface->group.attrs == NULL) {
  		ret = -ENOMEM;
  		goto error_free_setup_event_lines;
  	}
  	if (indio_dev->info->event_attrs)
  		memcpy(indio_dev->event_interface->group.attrs,
  		       indio_dev->info->event_attrs->attrs,
  		       sizeof(indio_dev->event_interface->group.attrs[0])
  		       *attrcount_orig);
  	attrn = attrcount_orig;
  	/* Add all elements from the list. */
  	list_for_each_entry(p,
  			    &indio_dev->event_interface->dev_attr_list,
  			    l)
  		indio_dev->event_interface->group.attrs[attrn++] =
  			&p->dev_attr.attr;
  	indio_dev->groups[indio_dev->groupcounter++] =
  		&indio_dev->event_interface->group;
  
  	return 0;
  
  error_free_setup_event_lines:
  	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
  	kfree(indio_dev->event_interface);
  error_ret:
  
  	return ret;
  }
  
  /**
   * iio_device_wakeup_eventset - Wakes up the event waitqueue
   * @indio_dev: The IIO device
   *
   * Wakes up the event waitqueue used for poll() and blocking read().
   * Should usually be called when the device is unregistered.
   */
  void iio_device_wakeup_eventset(struct iio_dev *indio_dev)
  {
  	if (indio_dev->event_interface == NULL)
  		return;
  	wake_up(&indio_dev->event_interface->wait);
  }
  
  void iio_device_unregister_eventset(struct iio_dev *indio_dev)
  {
  	if (indio_dev->event_interface == NULL)
  		return;
  	iio_free_chan_devattr_list(&indio_dev->event_interface->dev_attr_list);
  	kfree(indio_dev->event_interface->group.attrs);
  	kfree(indio_dev->event_interface);
  }