xref: /drivers/staging/iio/industrialio-core.c

/* The industrial I/O core
 *
 * 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/kernel.h>
#include <linux/module.h>
#include <linux/idr.h>
#include <linux/kdev_t.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/cdev.h>
#include <linux/slab.h>
#include <linux/anon_inodes.h>
#include "iio.h"
#include "iio_core.h"
#include "iio_core_trigger.h"
#include "sysfs.h"
#include "events.h"

/* IDA to assign each registered device a unique id*/
static DEFINE_IDA(iio_ida);

static dev_t iio_devt;

#define IIO_DEV_MAX 256
struct bus_type iio_bus_type = {
	.name = "iio",
};
EXPORT_SYMBOL(iio_bus_type);

static const char * const iio_data_type_name[] = {
	[IIO_RAW] = "raw",
	[IIO_PROCESSED] = "input",
};

static const char * const iio_direction[] = {
	[0] = "in",
	[1] = "out",
};

static const char * const iio_chan_type_name_spec[] = {
	[IIO_VOLTAGE] = "voltage",
	[IIO_CURRENT] = "current",
	[IIO_POWER] = "power",
	[IIO_ACCEL] = "accel",
	[IIO_ANGL_VEL] = "anglvel",
	[IIO_MAGN] = "magn",
	[IIO_LIGHT] = "illuminance",
	[IIO_INTENSITY] = "intensity",
	[IIO_PROXIMITY] = "proximity",
	[IIO_TEMP] = "temp",
	[IIO_INCLI] = "incli",
	[IIO_ROT] = "rot",
	[IIO_ANGL] = "angl",
	[IIO_TIMESTAMP] = "timestamp",
	[IIO_CAPACITANCE] = "capacitance",
};

static const char * const iio_modifier_names[] = {
	[IIO_MOD_X] = "x",
	[IIO_MOD_Y] = "y",
	[IIO_MOD_Z] = "z",
	[IIO_MOD_LIGHT_BOTH] = "both",
	[IIO_MOD_LIGHT_IR] = "ir",
};

/* relies on pairs of these shared then separate */
static const char * const iio_chan_info_postfix[] = {
	[IIO_CHAN_INFO_SCALE] = "scale",
	[IIO_CHAN_INFO_OFFSET] = "offset",
	[IIO_CHAN_INFO_CALIBSCALE] = "calibscale",
	[IIO_CHAN_INFO_CALIBBIAS] = "calibbias",
	[IIO_CHAN_INFO_PEAK] = "peak_raw",
	[IIO_CHAN_INFO_PEAK_SCALE] = "peak_scale",
	[IIO_CHAN_INFO_QUADRATURE_CORRECTION_RAW] = "quadrature_correction_raw",
	[IIO_CHAN_INFO_AVERAGE_RAW] = "mean_raw",
};

/**
 * struct iio_detected_event_list - list element for events that have occurred
 * @list:		linked list header
 * @ev:			the event itself
 */
struct iio_detected_event_list {
	struct list_head		list;
	struct iio_event_data		ev;
};

/**
 * struct iio_event_interface - chrdev interface for an event line
 * @dev:		device assocated with event interface
 * @wait:		wait queue to allow blocking reads of events
 * @event_list_lock:	mutex to protect the list of detected events
 * @det_events:		list of detected events
 * @max_events:		maximum number of events before new ones are dropped
 * @current_events:	number of events in detected list
 * @flags:		file operations related flags including busy flag.
 */
struct iio_event_interface {
	wait_queue_head_t			wait;
	struct mutex				event_list_lock;
	struct list_head			det_events;
	int					max_events;
	int					current_events;
	struct list_head dev_attr_list;
	unsigned long flags;
	struct attribute_group			group;
};

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_detected_event_list *ev;
	int ret = 0;

	/* Does anyone care? */
	mutex_lock(&ev_int->event_list_lock);
	if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
		if (ev_int->current_events == ev_int->max_events) {
			mutex_unlock(&ev_int->event_list_lock);
			return 0;
		}
		ev = kmalloc(sizeof(*ev), GFP_KERNEL);
		if (ev == NULL) {
			ret = -ENOMEM;
			mutex_unlock(&ev_int->event_list_lock);
			goto error_ret;
		}
		ev->ev.id = ev_code;
		ev->ev.timestamp = timestamp;

		list_add_tail(&ev->list, &ev_int->det_events);
		ev_int->current_events++;
		mutex_unlock(&ev_int->event_list_lock);
		wake_up_interruptible(&ev_int->wait);
	} else
		mutex_unlock(&ev_int->event_list_lock);

error_ret:
	return ret;
}
EXPORT_SYMBOL(iio_push_event);

/* This turns up an awful lot */
ssize_t iio_read_const_attr(struct device *dev,
			    struct device_attribute *attr,
			    char *buf)
{
	return sprintf(buf, "%s\n", to_iio_const_attr(attr)->string);
}
EXPORT_SYMBOL(iio_read_const_attr);

static ssize_t iio_event_chrdev_read(struct file *filep,
				     char __user *buf,
				     size_t count,
				     loff_t *f_ps)
{
	struct iio_event_interface *ev_int = filep->private_data;
	struct iio_detected_event_list *el;
	size_t len = sizeof(el->ev);
	int ret;

	if (count < len)
		return -EINVAL;

	mutex_lock(&ev_int->event_list_lock);
	if (list_empty(&ev_int->det_events)) {
		if (filep->f_flags & O_NONBLOCK) {
			ret = -EAGAIN;
			goto error_mutex_unlock;
		}
		mutex_unlock(&ev_int->event_list_lock);
		/* Blocking on device; waiting for something to be there */
		ret = wait_event_interruptible(ev_int->wait,
					       !list_empty(&ev_int
							   ->det_events));
		if (ret)
			goto error_ret;
		/* Single access device so no one else can get the data */
		mutex_lock(&ev_int->event_list_lock);
	}

	el = list_first_entry(&ev_int->det_events,
			      struct iio_detected_event_list,
			      list);
	if (copy_to_user(buf, &(el->ev), len)) {
		ret = -EFAULT;
		goto error_mutex_unlock;
	}
	list_del(&el->list);
	ev_int->current_events--;
	mutex_unlock(&ev_int->event_list_lock);
	kfree(el);

	return len;

error_mutex_unlock:
	mutex_unlock(&ev_int->event_list_lock);
error_ret:

	return ret;
}

static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{
	struct iio_event_interface *ev_int = filep->private_data;
	struct iio_detected_event_list *el, *t;

	mutex_lock(&ev_int->event_list_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.
	 */
	list_for_each_entry_safe(el, t, &ev_int->det_events, list) {
		list_del(&el->list);
		kfree(el);
	}
	ev_int->current_events = 0;
	mutex_unlock(&ev_int->event_list_lock);

	return 0;
}

static const struct file_operations iio_event_chrdev_fileops = {
	.read =  iio_event_chrdev_read,
	.release = iio_event_chrdev_release,
	.owner = THIS_MODULE,
	.llseek = noop_llseek,
};

static int iio_event_getfd(struct iio_dev *indio_dev)
{
	int fd;

	if (indio_dev->event_interface == NULL)
		return -ENODEV;

	mutex_lock(&indio_dev->event_interface->event_list_lock);
	if (test_and_set_bit(IIO_BUSY_BIT_POS,
			     &indio_dev->event_interface->flags)) {
		mutex_unlock(&indio_dev->event_interface->event_list_lock);
		return -EBUSY;
	}
	mutex_unlock(&indio_dev->event_interface->event_list_lock);
	fd = anon_inode_getfd("iio:event",
				&iio_event_chrdev_fileops,
				indio_dev->event_interface, O_RDONLY);
	if (fd < 0) {
		mutex_lock(&indio_dev->event_interface->event_list_lock);
		clear_bit(IIO_BUSY_BIT_POS, &indio_dev->event_interface->flags);
		mutex_unlock(&indio_dev->event_interface->event_list_lock);
	}
	return fd;
}

static int __init iio_init(void)
{
	int ret;

	/* Register sysfs bus */
	ret  = bus_register(&iio_bus_type);
	if (ret < 0) {
		printk(KERN_ERR
		       "%s could not register bus type\n",
			__FILE__);
		goto error_nothing;
	}

	ret = alloc_chrdev_region(&iio_devt, 0, IIO_DEV_MAX, "iio");
	if (ret < 0) {
		printk(KERN_ERR "%s: failed to allocate char dev region\n",
		       __FILE__);
		goto error_unregister_bus_type;
	}

	return 0;

error_unregister_bus_type:
	bus_unregister(&iio_bus_type);
error_nothing:
	return ret;
}

static void __exit iio_exit(void)
{
	if (iio_devt)
		unregister_chrdev_region(iio_devt, IIO_DEV_MAX);
	bus_unregister(&iio_bus_type);
}

static ssize_t iio_read_channel_info(struct device *dev,
				     struct device_attribute *attr,
				     char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int val, val2;
	int ret = indio_dev->info->read_raw(indio_dev, this_attr->c,
					    &val, &val2, this_attr->address);

	if (ret < 0)
		return ret;

	if (ret == IIO_VAL_INT)
		return sprintf(buf, "%d\n", val);
	else if (ret == IIO_VAL_INT_PLUS_MICRO) {
		if (val2 < 0)
			return sprintf(buf, "-%d.%06u\n", val, -val2);
		else
			return sprintf(buf, "%d.%06u\n", val, val2);
	} else if (ret == IIO_VAL_INT_PLUS_NANO) {
		if (val2 < 0)
			return sprintf(buf, "-%d.%09u\n", val, -val2);
		else
			return sprintf(buf, "%d.%09u\n", val, val2);
	} else
		return 0;
}

static ssize_t iio_write_channel_info(struct device *dev,
				      struct device_attribute *attr,
				      const char *buf,
				      size_t len)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int ret, integer = 0, fract = 0, fract_mult = 100000;
	bool integer_part = true, negative = false;

	/* Assumes decimal - precision based on number of digits */
	if (!indio_dev->info->write_raw)
		return -EINVAL;

	if (indio_dev->info->write_raw_get_fmt)
		switch (indio_dev->info->write_raw_get_fmt(indio_dev,
			this_attr->c, this_attr->address)) {
		case IIO_VAL_INT_PLUS_MICRO:
			fract_mult = 100000;
			break;
		case IIO_VAL_INT_PLUS_NANO:
			fract_mult = 100000000;
			break;
		default:
			return -EINVAL;
		}

	if (buf[0] == '-') {
		negative = true;
		buf++;
	}

	while (*buf) {
		if ('0' <= *buf && *buf <= '9') {
			if (integer_part)
				integer = integer*10 + *buf - '0';
			else {
				fract += fract_mult*(*buf - '0');
				if (fract_mult == 1)
					break;
				fract_mult /= 10;
			}
		} else if (*buf == '\n') {
			if (*(buf + 1) == '\0')
				break;
			else
				return -EINVAL;
		} else if (*buf == '.') {
			integer_part = false;
		} else {
			return -EINVAL;
		}
		buf++;
	}
	if (negative) {
		if (integer)
			integer = -integer;
		else
			fract = -fract;
	}

	ret = indio_dev->info->write_raw(indio_dev, this_attr->c,
					 integer, fract, this_attr->address);
	if (ret)
		return ret;

	return len;
}

static
int __iio_device_attr_init(struct device_attribute *dev_attr,
			   const char *postfix,
			   struct iio_chan_spec const *chan,
			   ssize_t (*readfunc)(struct device *dev,
					       struct device_attribute *attr,
					       char *buf),
			   ssize_t (*writefunc)(struct device *dev,
						struct device_attribute *attr,
						const char *buf,
						size_t len),
			   bool generic)
{
	int ret;
	char *name_format, *full_postfix;
	sysfs_attr_init(&dev_attr->attr);

	/* Build up postfix of <extend_name>_<modifier>_postfix */
	if (chan->modified && !generic) {
		if (chan->extend_name)
			full_postfix = kasprintf(GFP_KERNEL, "%s_%s_%s",
						 iio_modifier_names[chan
								    ->channel2],
						 chan->extend_name,
						 postfix);
		else
			full_postfix = kasprintf(GFP_KERNEL, "%s_%s",
						 iio_modifier_names[chan
								    ->channel2],
						 postfix);
	} else {
		if (chan->extend_name == NULL)
			full_postfix = kstrdup(postfix, GFP_KERNEL);
		else
			full_postfix = kasprintf(GFP_KERNEL,
						 "%s_%s",
						 chan->extend_name,
						 postfix);
	}
	if (full_postfix == NULL) {
		ret = -ENOMEM;
		goto error_ret;
	}

	if (chan->differential) { /* Differential  can not have modifier */
		if (generic)
			name_format
				= kasprintf(GFP_KERNEL, "%s_%s-%s_%s",
					    iio_direction[chan->output],
					    iio_chan_type_name_spec[chan->type],
					    iio_chan_type_name_spec[chan->type],
					    full_postfix);
		else if (chan->indexed)
			name_format
				= kasprintf(GFP_KERNEL, "%s_%s%d-%s%d_%s",
					    iio_direction[chan->output],
					    iio_chan_type_name_spec[chan->type],
					    chan->channel,
					    iio_chan_type_name_spec[chan->type],
					    chan->channel2,
					    full_postfix);
		else {
			WARN_ON("Differential channels must be indexed\n");
			ret = -EINVAL;
			goto error_free_full_postfix;
		}
	} else { /* Single ended */
		if (generic)
			name_format
				= kasprintf(GFP_KERNEL, "%s_%s_%s",
					    iio_direction[chan->output],
					    iio_chan_type_name_spec[chan->type],
					    full_postfix);
		else if (chan->indexed)
			name_format
				= kasprintf(GFP_KERNEL, "%s_%s%d_%s",
					    iio_direction[chan->output],
					    iio_chan_type_name_spec[chan->type],
					    chan->channel,
					    full_postfix);
		else
			name_format
				= kasprintf(GFP_KERNEL, "%s_%s_%s",
					    iio_direction[chan->output],
					    iio_chan_type_name_spec[chan->type],
					    full_postfix);
	}
	if (name_format == NULL) {
		ret = -ENOMEM;
		goto error_free_full_postfix;
	}
	dev_attr->attr.name = kasprintf(GFP_KERNEL,
					name_format,
					chan->channel,
					chan->channel2);
	if (dev_attr->attr.name == NULL) {
		ret = -ENOMEM;
		goto error_free_name_format;
	}

	if (readfunc) {
		dev_attr->attr.mode |= S_IRUGO;
		dev_attr->show = readfunc;
	}

	if (writefunc) {
		dev_attr->attr.mode |= S_IWUSR;
		dev_attr->store = writefunc;
	}
	kfree(name_format);
	kfree(full_postfix);

	return 0;

error_free_name_format:
	kfree(name_format);
error_free_full_postfix:
	kfree(full_postfix);
error_ret:
	return ret;
}

static void __iio_device_attr_deinit(struct device_attribute *dev_attr)
{
	kfree(dev_attr->attr.name);
}

int __iio_add_chan_devattr(const char *postfix,
			   struct iio_chan_spec const *chan,
			   ssize_t (*readfunc)(struct device *dev,
					       struct device_attribute *attr,
					       char *buf),
			   ssize_t (*writefunc)(struct device *dev,
						struct device_attribute *attr,
						const char *buf,
						size_t len),
			   u64 mask,
			   bool generic,
			   struct device *dev,
			   struct list_head *attr_list)
{
	int ret;
	struct iio_dev_attr *iio_attr, *t;

	iio_attr = kzalloc(sizeof *iio_attr, GFP_KERNEL);
	if (iio_attr == NULL) {
		ret = -ENOMEM;
		goto error_ret;
	}
	ret = __iio_device_attr_init(&iio_attr->dev_attr,
				     postfix, chan,
				     readfunc, writefunc, generic);
	if (ret)
		goto error_iio_dev_attr_free;
	iio_attr->c = chan;
	iio_attr->address = mask;
	list_for_each_entry(t, attr_list, l)
		if (strcmp(t->dev_attr.attr.name,
			   iio_attr->dev_attr.attr.name) == 0) {
			if (!generic)
				dev_err(dev, "tried to double register : %s\n",
					t->dev_attr.attr.name);
			ret = -EBUSY;
			goto error_device_attr_deinit;
		}
	list_add(&iio_attr->l, attr_list);

	return 0;

error_device_attr_deinit:
	__iio_device_attr_deinit(&iio_attr->dev_attr);
error_iio_dev_attr_free:
	kfree(iio_attr);
error_ret:
	return ret;
}

static int iio_device_add_channel_sysfs(struct iio_dev *indio_dev,
					struct iio_chan_spec const *chan)
{
	int ret, i, attrcount = 0;

	if (chan->channel < 0)
		return 0;

	ret = __iio_add_chan_devattr(iio_data_type_name[chan->processed_val],
				     chan,
				     &iio_read_channel_info,
				     (chan->output ?
				      &iio_write_channel_info : NULL),
				     0,
				     0,
				     &indio_dev->dev,
				     &indio_dev->channel_attr_list);
	if (ret)
		goto error_ret;
	attrcount++;

	for_each_set_bit(i, &chan->info_mask, sizeof(long)*8) {
		ret = __iio_add_chan_devattr(iio_chan_info_postfix[i/2],
					     chan,
					     &iio_read_channel_info,
					     &iio_write_channel_info,
					     i/2,
					     !(i%2),
					     &indio_dev->dev,
					     &indio_dev->channel_attr_list);
		if (ret == -EBUSY && (i%2 == 0)) {
			ret = 0;
			continue;
		}
		if (ret < 0)
			goto error_ret;
		attrcount++;
	}
	ret = attrcount;
error_ret:
	return ret;
}

static void iio_device_remove_and_free_read_attr(struct iio_dev *indio_dev,
						 struct iio_dev_attr *p)
{
	kfree(p->dev_attr.attr.name);
	kfree(p);
}

static ssize_t iio_show_dev_name(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	return sprintf(buf, "%s\n", indio_dev->name);
}

static DEVICE_ATTR(name, S_IRUGO, iio_show_dev_name, NULL);

static int iio_device_register_sysfs(struct iio_dev *indio_dev)
{
	int i, ret = 0, attrcount, attrn, attrcount_orig = 0;
	struct iio_dev_attr *p, *n;
	struct attribute **attr;

	/* First count elements in any existing group */
	if (indio_dev->info->attrs) {
		attr = indio_dev->info->attrs->attrs;
		while (*attr++ != NULL)
			attrcount_orig++;
	}
	attrcount = attrcount_orig;
	/*
	 * New channel registration method - relies on the fact a group does
	 *  not need to be initialized if it is name is NULL.
	 */
	INIT_LIST_HEAD(&indio_dev->channel_attr_list);
	if (indio_dev->channels)
		for (i = 0; i < indio_dev->num_channels; i++) {
			ret = iio_device_add_channel_sysfs(indio_dev,
							   &indio_dev
							   ->channels[i]);
			if (ret < 0)
				goto error_clear_attrs;
			attrcount += ret;
		}

	if (indio_dev->name)
		attrcount++;

	indio_dev->chan_attr_group.attrs
		= kzalloc(sizeof(indio_dev->chan_attr_group.attrs[0])*
			  (attrcount + 1),
			  GFP_KERNEL);
	if (indio_dev->chan_attr_group.attrs == NULL) {
		ret = -ENOMEM;
		goto error_clear_attrs;
	}
	/* Copy across original attributes */
	if (indio_dev->info->attrs)
		memcpy(indio_dev->chan_attr_group.attrs,
		       indio_dev->info->attrs->attrs,
		       sizeof(indio_dev->chan_attr_group.attrs[0])
		       *attrcount_orig);
	attrn = attrcount_orig;
	/* Add all elements from the list. */
	list_for_each_entry(p, &indio_dev->channel_attr_list, l)
		indio_dev->chan_attr_group.attrs[attrn++] = &p->dev_attr.attr;
	if (indio_dev->name)
		indio_dev->chan_attr_group.attrs[attrn++] = &dev_attr_name.attr;

	indio_dev->groups[indio_dev->groupcounter++] =
		&indio_dev->chan_attr_group;

	return 0;

error_clear_attrs:
	list_for_each_entry_safe(p, n,
				 &indio_dev->channel_attr_list, l) {
		list_del(&p->l);
		iio_device_remove_and_free_read_attr(indio_dev, p);
	}

	return ret;
}

static void iio_device_unregister_sysfs(struct iio_dev *indio_dev)
{

	struct iio_dev_attr *p, *n;

	list_for_each_entry_safe(p, n, &indio_dev->channel_attr_list, l) {
		list_del(&p->l);
		iio_device_remove_and_free_read_attr(indio_dev, p);
	}
	kfree(indio_dev->chan_attr_group.attrs);
}

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 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_get_drvdata(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->address,
						  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_get_drvdata(dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int val = indio_dev->info->read_event_config(indio_dev,
						     this_attr->address);

	if (val < 0)
		return val;
	else
		return sprintf(buf, "%d\n", val);
}

static ssize_t iio_ev_value_show(struct device *dev,
				 struct device_attribute *attr,
				 char *buf)
{
	struct iio_dev *indio_dev = dev_get_drvdata(dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	int val, ret;

	ret = indio_dev->info->read_event_value(indio_dev,
						this_attr->address, &val);
	if (ret < 0)
		return ret;

	return sprintf(buf, "%d\n", val);
}

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_get_drvdata(dev);
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	unsigned long val;
	int ret;

	ret = strict_strtoul(buf, 10, &val);
	if (ret)
		return ret;

	ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
						 val);
	if (ret < 0)
		return ret;

	return len;
}

static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
				      struct iio_chan_spec const *chan)
{
	int ret = 0, i, attrcount = 0;
	u64 mask = 0;
	char *postfix;
	if (!chan->event_mask)
		return 0;

	for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
		postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
				    iio_ev_type_text[i/IIO_EV_DIR_MAX],
				    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
		if (postfix == NULL) {
			ret = -ENOMEM;
			goto error_ret;
		}
		if (chan->modified)
			mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel,
						  i/IIO_EV_DIR_MAX,
						  i%IIO_EV_DIR_MAX);
		else if (chan->differential)
			mask = IIO_EVENT_CODE(chan->type,
					      0, 0,
					      i%IIO_EV_DIR_MAX,
					      i/IIO_EV_DIR_MAX,
					      0,
					      chan->channel,
					      chan->channel2);
		else
			mask = IIO_UNMOD_EVENT_CODE(chan->type,
						    chan->channel,
						    i/IIO_EV_DIR_MAX,
						    i%IIO_EV_DIR_MAX);

		ret = __iio_add_chan_devattr(postfix,
					     chan,
					     &iio_ev_state_show,
					     iio_ev_state_store,
					     mask,
					     0,
					     &indio_dev->dev,
					     &indio_dev->event_interface->
					     dev_attr_list);
		kfree(postfix);
		if (ret)
			goto error_ret;
		attrcount++;
		postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
				    iio_ev_type_text[i/IIO_EV_DIR_MAX],
				    iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
		if (postfix == NULL) {
			ret = -ENOMEM;
			goto error_ret;
		}
		ret = __iio_add_chan_devattr(postfix, chan,
					     iio_ev_value_show,
					     iio_ev_value_store,
					     mask,
					     0,
					     &indio_dev->dev,
					     &indio_dev->event_interface->
					     dev_attr_list);
		kfree(postfix);
		if (ret)
			goto error_ret;
		attrcount++;
	}
	ret = attrcount;
error_ret:
	return ret;
}

static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
{
	struct iio_dev_attr *p, *n;
	list_for_each_entry_safe(p, n,
				 &indio_dev->event_interface->
				 dev_attr_list, l) {
		kfree(p->dev_attr.attr.name);
		kfree(p);
	}
}

static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
{
	int j, ret, attrcount = 0;

	INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
	/* 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)
			goto error_clear_attrs;
		attrcount += ret;
	}
	return attrcount;

error_clear_attrs:
	__iio_remove_event_config_attrs(indio_dev);

	return ret;
}

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].event_mask != 0)
			return true;
	return false;
}

static void iio_setup_ev_int(struct iio_event_interface *ev_int)
{
	mutex_init(&ev_int->event_list_lock);
	/* discussion point - make this variable? */
	ev_int->max_events = 10;
	ev_int->current_events = 0;
	INIT_LIST_HEAD(&ev_int->det_events);
	init_waitqueue_head(&ev_int->wait);
}

static const char *iio_event_group_name = "events";
static 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;
	}

	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 =
		kzalloc(sizeof(indio_dev->event_interface->group.attrs[0])
			*(attrcount + 1),
			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_remove_event_config_attrs(indio_dev);
	kfree(indio_dev->event_interface);
error_ret:

	return ret;
}

static void iio_device_unregister_eventset(struct iio_dev *indio_dev)
{
	if (indio_dev->event_interface == NULL)
		return;
	__iio_remove_event_config_attrs(indio_dev);
	kfree(indio_dev->event_interface->group.attrs);
	kfree(indio_dev->event_interface);
}

static void iio_dev_release(struct device *device)
{
	struct iio_dev *indio_dev = container_of(device, struct iio_dev, dev);
	cdev_del(&indio_dev->chrdev);
	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
		iio_device_unregister_trigger_consumer(indio_dev);
	iio_device_unregister_eventset(indio_dev);
	iio_device_unregister_sysfs(indio_dev);
}

static struct device_type iio_dev_type = {
	.name = "iio_device",
	.release = iio_dev_release,
};

struct iio_dev *iio_allocate_device(int sizeof_priv)
{
	struct iio_dev *dev;
	size_t alloc_size;

	alloc_size = sizeof(struct iio_dev);
	if (sizeof_priv) {
		alloc_size = ALIGN(alloc_size, IIO_ALIGN);
		alloc_size += sizeof_priv;
	}
	/* ensure 32-byte alignment of whole construct ? */
	alloc_size += IIO_ALIGN - 1;

	dev = kzalloc(alloc_size, GFP_KERNEL);

	if (dev) {
		dev->dev.groups = dev->groups;
		dev->dev.type = &iio_dev_type;
		dev->dev.bus = &iio_bus_type;
		device_initialize(&dev->dev);
		dev_set_drvdata(&dev->dev, (void *)dev);
		mutex_init(&dev->mlock);

		dev->id = ida_simple_get(&iio_ida, 0, 0, GFP_KERNEL);
		if (dev->id < 0) {
			/* cannot use a dev_err as the name isn't available */
			printk(KERN_ERR "Failed to get id\n");
			kfree(dev);
			return NULL;
		}
		dev_set_name(&dev->dev, "iio:device%d", dev->id);
	}

	return dev;
}
EXPORT_SYMBOL(iio_allocate_device);

void iio_free_device(struct iio_dev *dev)
{
	if (dev) {
		ida_simple_remove(&iio_ida, dev->id);
		kfree(dev);
	}
}
EXPORT_SYMBOL(iio_free_device);

/**
 * iio_chrdev_open() - chrdev file open for buffer access and ioctls
 **/
static int iio_chrdev_open(struct inode *inode, struct file *filp)
{
	struct iio_dev *indio_dev = container_of(inode->i_cdev,
						struct iio_dev, chrdev);
	filp->private_data = indio_dev;

	return iio_chrdev_buffer_open(indio_dev);
}

/**
 * iio_chrdev_release() - chrdev file close buffer access and ioctls
 **/
static int iio_chrdev_release(struct inode *inode, struct file *filp)
{
	iio_chrdev_buffer_release(container_of(inode->i_cdev,
					     struct iio_dev, chrdev));
	return 0;
}

/* Somewhat of a cross file organization violation - ioctls here are actually
 * event related */
static long iio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
	struct iio_dev *indio_dev = filp->private_data;
	int __user *ip = (int __user *)arg;
	int fd;

	if (cmd == IIO_GET_EVENT_FD_IOCTL) {
		fd = iio_event_getfd(indio_dev);
		if (copy_to_user(ip, &fd, sizeof(fd)))
			return -EFAULT;
		return 0;
	}
	return -EINVAL;
}

static const struct file_operations iio_buffer_fileops = {
	.read = iio_buffer_read_first_n_outer_addr,
	.release = iio_chrdev_release,
	.open = iio_chrdev_open,
	.poll = iio_buffer_poll_addr,
	.owner = THIS_MODULE,
	.llseek = noop_llseek,
	.unlocked_ioctl = iio_ioctl,
	.compat_ioctl = iio_ioctl,
};

int iio_device_register(struct iio_dev *indio_dev)
{
	int ret;

	/* configure elements for the chrdev */
	indio_dev->dev.devt = MKDEV(MAJOR(iio_devt), indio_dev->id);

	ret = iio_device_register_sysfs(indio_dev);
	if (ret) {
		dev_err(indio_dev->dev.parent,
			"Failed to register sysfs interfaces\n");
		goto error_ret;
	}
	ret = iio_device_register_eventset(indio_dev);
	if (ret) {
		dev_err(indio_dev->dev.parent,
			"Failed to register event set\n");
		goto error_free_sysfs;
	}
	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
		iio_device_register_trigger_consumer(indio_dev);

	ret = device_add(&indio_dev->dev);
	if (ret < 0)
		goto error_unreg_eventset;
	cdev_init(&indio_dev->chrdev, &iio_buffer_fileops);
	indio_dev->chrdev.owner = indio_dev->info->driver_module;
	ret = cdev_add(&indio_dev->chrdev, indio_dev->dev.devt, 1);
	if (ret < 0)
		goto error_del_device;
	return 0;

error_del_device:
	device_del(&indio_dev->dev);
error_unreg_eventset:
	iio_device_unregister_eventset(indio_dev);
error_free_sysfs:
	iio_device_unregister_sysfs(indio_dev);
error_ret:
	return ret;
}
EXPORT_SYMBOL(iio_device_register);

void iio_device_unregister(struct iio_dev *indio_dev)
{
	device_unregister(&indio_dev->dev);
}
EXPORT_SYMBOL(iio_device_unregister);
subsys_initcall(iio_init);
module_exit(iio_exit);

MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
MODULE_DESCRIPTION("Industrial I/O core");
MODULE_LICENSE("GPL");