/* 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.
   *
   * Handling of buffer allocation / resizing.
   *
   *
   * Things to look at here.
   * - Better memory allocation techniques?
   * - Alternative access techniques?
   */
  #include <linux/kernel.h>
  #include <linux/export.h>
  #include <linux/device.h>
  #include <linux/fs.h>
  #include <linux/cdev.h>
  #include <linux/slab.h>
  #include <linux/poll.h>
  #include <linux/sched.h>
  
  #include <linux/iio/iio.h>
  #include "iio_core.h"
  #include <linux/iio/sysfs.h>
  #include <linux/iio/buffer.h>
  
  static const char * const iio_endian_prefix[] = {
  	[IIO_BE] = "be",
  	[IIO_LE] = "le",
  };
  
  static bool iio_buffer_is_active(struct iio_buffer *buf)
  {
  	return !list_empty(&buf->buffer_list);
  }
  
  static bool iio_buffer_data_available(struct iio_buffer *buf)
  {
  	if (buf->access->data_available)
  		return buf->access->data_available(buf);
  
  	return buf->stufftoread;
  }
  
  /**
   * iio_buffer_read_first_n_outer() - chrdev read for buffer access
   *
   * This function relies on all buffer implementations having an
   * iio_buffer as their first element.
   **/
  ssize_t iio_buffer_read_first_n_outer(struct file *filp, char __user *buf,
  				      size_t n, loff_t *f_ps)
  {
  	struct iio_dev *indio_dev = filp->private_data;
  	struct iio_buffer *rb = indio_dev->buffer;
  	int ret;
  
  	if (!indio_dev->info)
  		return -ENODEV;
  
  	if (!rb || !rb->access->read_first_n)
  		return -EINVAL;
  
  	do {
  		if (!iio_buffer_data_available(rb)) {
  			if (filp->f_flags & O_NONBLOCK)
  				return -EAGAIN;
  
  			ret = wait_event_interruptible(rb->pollq,
  					iio_buffer_data_available(rb) ||
  					indio_dev->info == NULL);
  			if (ret)
  				return ret;
  			if (indio_dev->info == NULL)
  				return -ENODEV;
  		}
  
  		ret = rb->access->read_first_n(rb, n, buf);
  		if (ret == 0 && (filp->f_flags & O_NONBLOCK))
  			ret = -EAGAIN;
  	 } while (ret == 0);
  
  	return ret;
  }
  
  /**
   * iio_buffer_poll() - poll the buffer to find out if it has data
   */
  unsigned int iio_buffer_poll(struct file *filp,
  			     struct poll_table_struct *wait)
  {
  	struct iio_dev *indio_dev = filp->private_data;
  	struct iio_buffer *rb = indio_dev->buffer;
  
  	if (!indio_dev->info)
  		return -ENODEV;
  
  	poll_wait(filp, &rb->pollq, wait);
  	if (iio_buffer_data_available(rb))
  		return POLLIN | POLLRDNORM;
  	/* need a way of knowing if there may be enough data... */
  	return 0;
  }
  
  /**
   * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue
   * @indio_dev: The IIO device
   *
   * Wakes up the event waitqueue used for poll(). Should usually
   * be called when the device is unregistered.
   */
  void iio_buffer_wakeup_poll(struct iio_dev *indio_dev)
  {
  	if (!indio_dev->buffer)
  		return;
  
  	wake_up(&indio_dev->buffer->pollq);
  }
  
  void iio_buffer_init(struct iio_buffer *buffer)
  {
  	INIT_LIST_HEAD(&buffer->demux_list);
  	INIT_LIST_HEAD(&buffer->buffer_list);
  	init_waitqueue_head(&buffer->pollq);
  	kref_init(&buffer->ref);
  }
  EXPORT_SYMBOL(iio_buffer_init);
  
  static ssize_t iio_show_scan_index(struct device *dev,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	return sprintf(buf, "%u
  ", to_iio_dev_attr(attr)->c->scan_index);
  }
  
  static ssize_t iio_show_fixed_type(struct device *dev,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  	u8 type = this_attr->c->scan_type.endianness;
  
  	if (type == IIO_CPU) {
  #ifdef __LITTLE_ENDIAN
  		type = IIO_LE;
  #else
  		type = IIO_BE;
  #endif
  	}
  	return sprintf(buf, "%s:%c%d/%d>>%u
  ",
  		       iio_endian_prefix[type],
  		       this_attr->c->scan_type.sign,
  		       this_attr->c->scan_type.realbits,
  		       this_attr->c->scan_type.storagebits,
  		       this_attr->c->scan_type.shift);
  }
  
  static ssize_t iio_scan_el_show(struct device *dev,
  				struct device_attribute *attr,
  				char *buf)
  {
  	int ret;
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  
  	/* Ensure ret is 0 or 1. */
  	ret = !!test_bit(to_iio_dev_attr(attr)->address,
  		       indio_dev->buffer->scan_mask);
  
  	return sprintf(buf, "%d
  ", ret);
  }
  
  static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
  {
  	clear_bit(bit, buffer->scan_mask);
  	return 0;
  }
  
  static ssize_t iio_scan_el_store(struct device *dev,
  				 struct device_attribute *attr,
  				 const char *buf,
  				 size_t len)
  {
  	int ret;
  	bool state;
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_buffer *buffer = indio_dev->buffer;
  	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
  
  	ret = strtobool(buf, &state);
  	if (ret < 0)
  		return ret;
  	mutex_lock(&indio_dev->mlock);
  	if (iio_buffer_is_active(indio_dev->buffer)) {
  		ret = -EBUSY;
  		goto error_ret;
  	}
  	ret = iio_scan_mask_query(indio_dev, buffer, this_attr->address);
  	if (ret < 0)
  		goto error_ret;
  	if (!state && ret) {
  		ret = iio_scan_mask_clear(buffer, this_attr->address);
  		if (ret)
  			goto error_ret;
  	} else if (state && !ret) {
  		ret = iio_scan_mask_set(indio_dev, buffer, this_attr->address);
  		if (ret)
  			goto error_ret;
  	}
  
  error_ret:
  	mutex_unlock(&indio_dev->mlock);
  
  	return ret < 0 ? ret : len;
  
  }
  
  static ssize_t iio_scan_el_ts_show(struct device *dev,
  				   struct device_attribute *attr,
  				   char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	return sprintf(buf, "%d
  ", indio_dev->buffer->scan_timestamp);
  }
  
  static ssize_t iio_scan_el_ts_store(struct device *dev,
  				    struct device_attribute *attr,
  				    const char *buf,
  				    size_t len)
  {
  	int ret;
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	bool state;
  
  	ret = strtobool(buf, &state);
  	if (ret < 0)
  		return ret;
  
  	mutex_lock(&indio_dev->mlock);
  	if (iio_buffer_is_active(indio_dev->buffer)) {
  		ret = -EBUSY;
  		goto error_ret;
  	}
  	indio_dev->buffer->scan_timestamp = state;
  error_ret:
  	mutex_unlock(&indio_dev->mlock);
  
  	return ret ? ret : len;
  }
  
  static int iio_buffer_add_channel_sysfs(struct iio_dev *indio_dev,
  					const struct iio_chan_spec *chan)
  {
  	int ret, attrcount = 0;
  	struct iio_buffer *buffer = indio_dev->buffer;
  
  	ret = __iio_add_chan_devattr("index",
  				     chan,
  				     &iio_show_scan_index,
  				     NULL,
  				     0,
  				     IIO_SEPARATE,
  				     &indio_dev->dev,
  				     &buffer->scan_el_dev_attr_list);
  	if (ret)
  		goto error_ret;
  	attrcount++;
  	ret = __iio_add_chan_devattr("type",
  				     chan,
  				     &iio_show_fixed_type,
  				     NULL,
  				     0,
  				     0,
  				     &indio_dev->dev,
  				     &buffer->scan_el_dev_attr_list);
  	if (ret)
  		goto error_ret;
  	attrcount++;
  	if (chan->type != IIO_TIMESTAMP)
  		ret = __iio_add_chan_devattr("en",
  					     chan,
  					     &iio_scan_el_show,
  					     &iio_scan_el_store,
  					     chan->scan_index,
  					     0,
  					     &indio_dev->dev,
  					     &buffer->scan_el_dev_attr_list);
  	else
  		ret = __iio_add_chan_devattr("en",
  					     chan,
  					     &iio_scan_el_ts_show,
  					     &iio_scan_el_ts_store,
  					     chan->scan_index,
  					     0,
  					     &indio_dev->dev,
  					     &buffer->scan_el_dev_attr_list);
  	if (ret)
  		goto error_ret;
  	attrcount++;
  	ret = attrcount;
  error_ret:
  	return ret;
  }
  
  static const char * const iio_scan_elements_group_name = "scan_elements";
  
  int iio_buffer_register(struct iio_dev *indio_dev,
  			const struct iio_chan_spec *channels,
  			int num_channels)
  {
  	struct iio_dev_attr *p;
  	struct attribute **attr;
  	struct iio_buffer *buffer = indio_dev->buffer;
  	int ret, i, attrn, attrcount, attrcount_orig = 0;
  
  	if (buffer->attrs)
  		indio_dev->groups[indio_dev->groupcounter++] = buffer->attrs;
  
  	if (buffer->scan_el_attrs != NULL) {
  		attr = buffer->scan_el_attrs->attrs;
  		while (*attr++ != NULL)
  			attrcount_orig++;
  	}
  	attrcount = attrcount_orig;
  	INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
  	if (channels) {
  		/* new magic */
  		for (i = 0; i < num_channels; i++) {
  			if (channels[i].scan_index < 0)
  				continue;
  
  			/* Establish necessary mask length */
  			if (channels[i].scan_index >
  			    (int)indio_dev->masklength - 1)
  				indio_dev->masklength
  					= channels[i].scan_index + 1;
  
  			ret = iio_buffer_add_channel_sysfs(indio_dev,
  							 &channels[i]);
  			if (ret < 0)
  				goto error_cleanup_dynamic;
  			attrcount += ret;
  			if (channels[i].type == IIO_TIMESTAMP)
  				indio_dev->scan_index_timestamp =
  					channels[i].scan_index;
  		}
  		if (indio_dev->masklength && buffer->scan_mask == NULL) {
  			buffer->scan_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
  						    sizeof(*buffer->scan_mask),
  						    GFP_KERNEL);
  			if (buffer->scan_mask == NULL) {
  				ret = -ENOMEM;
  				goto error_cleanup_dynamic;
  			}
  		}
  	}
  
  	buffer->scan_el_group.name = iio_scan_elements_group_name;
  
  	buffer->scan_el_group.attrs = kcalloc(attrcount + 1,
  					      sizeof(buffer->scan_el_group.attrs[0]),
  					      GFP_KERNEL);
  	if (buffer->scan_el_group.attrs == NULL) {
  		ret = -ENOMEM;
  		goto error_free_scan_mask;
  	}
  	if (buffer->scan_el_attrs)
  		memcpy(buffer->scan_el_group.attrs, buffer->scan_el_attrs,
  		       sizeof(buffer->scan_el_group.attrs[0])*attrcount_orig);
  	attrn = attrcount_orig;
  
  	list_for_each_entry(p, &buffer->scan_el_dev_attr_list, l)
  		buffer->scan_el_group.attrs[attrn++] = &p->dev_attr.attr;
  	indio_dev->groups[indio_dev->groupcounter++] = &buffer->scan_el_group;
  
  	return 0;
  
  error_free_scan_mask:
  	kfree(buffer->scan_mask);
  error_cleanup_dynamic:
  	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
  
  	return ret;
  }
  EXPORT_SYMBOL(iio_buffer_register);
  
  void iio_buffer_unregister(struct iio_dev *indio_dev)
  {
  	kfree(indio_dev->buffer->scan_mask);
  	kfree(indio_dev->buffer->scan_el_group.attrs);
  	iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
  }
  EXPORT_SYMBOL(iio_buffer_unregister);
  
  ssize_t iio_buffer_read_length(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	struct iio_buffer *buffer = indio_dev->buffer;
  
  	if (buffer->access->get_length)
  		return sprintf(buf, "%d
  ",
  			       buffer->access->get_length(buffer));
  
  	return 0;
  }
  EXPORT_SYMBOL(iio_buffer_read_length);
  
  ssize_t iio_buffer_write_length(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_buffer *buffer = indio_dev->buffer;
  	unsigned int val;
  	int ret;
  
  	ret = kstrtouint(buf, 10, &val);
  	if (ret)
  		return ret;
  
  	if (buffer->access->get_length)
  		if (val == buffer->access->get_length(buffer))
  			return len;
  
  	mutex_lock(&indio_dev->mlock);
  	if (iio_buffer_is_active(indio_dev->buffer)) {
  		ret = -EBUSY;
  	} else {
  		if (buffer->access->set_length)
  			buffer->access->set_length(buffer, val);
  		ret = 0;
  	}
  	mutex_unlock(&indio_dev->mlock);
  
  	return ret ? ret : len;
  }
  EXPORT_SYMBOL(iio_buffer_write_length);
  
  ssize_t iio_buffer_show_enable(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	return sprintf(buf, "%d
  ", iio_buffer_is_active(indio_dev->buffer));
  }
  EXPORT_SYMBOL(iio_buffer_show_enable);
  
  /* Note NULL used as error indicator as it doesn't make sense. */
  static const unsigned long *iio_scan_mask_match(const unsigned long *av_masks,
  					  unsigned int masklength,
  					  const unsigned long *mask)
  {
  	if (bitmap_empty(mask, masklength))
  		return NULL;
  	while (*av_masks) {
  		if (bitmap_subset(mask, av_masks, masklength))
  			return av_masks;
  		av_masks += BITS_TO_LONGS(masklength);
  	}
  	return NULL;
  }
  
  static int iio_compute_scan_bytes(struct iio_dev *indio_dev,
  				const unsigned long *mask, bool timestamp)
  {
  	const struct iio_chan_spec *ch;
  	unsigned bytes = 0;
  	int length, i;
  
  	/* How much space will the demuxed element take? */
  	for_each_set_bit(i, mask,
  			 indio_dev->masklength) {
  		ch = iio_find_channel_from_si(indio_dev, i);
  		length = ch->scan_type.storagebits / 8;
  		bytes = ALIGN(bytes, length);
  		bytes += length;
  	}
  	if (timestamp) {
  		ch = iio_find_channel_from_si(indio_dev,
  					      indio_dev->scan_index_timestamp);
  		length = ch->scan_type.storagebits / 8;
  		bytes = ALIGN(bytes, length);
  		bytes += length;
  	}
  	return bytes;
  }
  
  static void iio_buffer_activate(struct iio_dev *indio_dev,
  	struct iio_buffer *buffer)
  {
  	iio_buffer_get(buffer);
  	list_add(&buffer->buffer_list, &indio_dev->buffer_list);
  }
  
  static void iio_buffer_deactivate(struct iio_buffer *buffer)
  {
  	list_del_init(&buffer->buffer_list);
  	iio_buffer_put(buffer);
  }
  
  void iio_disable_all_buffers(struct iio_dev *indio_dev)
  {
  	struct iio_buffer *buffer, *_buffer;
  
  	if (list_empty(&indio_dev->buffer_list))
  		return;
  
  	if (indio_dev->setup_ops->predisable)
  		indio_dev->setup_ops->predisable(indio_dev);
  
  	list_for_each_entry_safe(buffer, _buffer,
  			&indio_dev->buffer_list, buffer_list)
  		iio_buffer_deactivate(buffer);
  
  	indio_dev->currentmode = INDIO_DIRECT_MODE;
  	if (indio_dev->setup_ops->postdisable)
  		indio_dev->setup_ops->postdisable(indio_dev);
  
  	if (indio_dev->available_scan_masks == NULL)
  		kfree(indio_dev->active_scan_mask);
  }
  
  static void iio_buffer_update_bytes_per_datum(struct iio_dev *indio_dev,
  	struct iio_buffer *buffer)
  {
  	unsigned int bytes;
  
  	if (!buffer->access->set_bytes_per_datum)
  		return;
  
  	bytes = iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
  		buffer->scan_timestamp);
  
  	buffer->access->set_bytes_per_datum(buffer, bytes);
  }
  
  static int __iio_update_buffers(struct iio_dev *indio_dev,
  		       struct iio_buffer *insert_buffer,
  		       struct iio_buffer *remove_buffer)
  {
  	int ret;
  	int success = 0;
  	struct iio_buffer *buffer;
  	unsigned long *compound_mask;
  	const unsigned long *old_mask;
  
  	/* Wind down existing buffers - iff there are any */
  	if (!list_empty(&indio_dev->buffer_list)) {
  		if (indio_dev->setup_ops->predisable) {
  			ret = indio_dev->setup_ops->predisable(indio_dev);
  			if (ret)
  				goto error_ret;
  		}
  		indio_dev->currentmode = INDIO_DIRECT_MODE;
  		if (indio_dev->setup_ops->postdisable) {
  			ret = indio_dev->setup_ops->postdisable(indio_dev);
  			if (ret)
  				goto error_ret;
  		}
  	}
  	/* Keep a copy of current setup to allow roll back */
  	old_mask = indio_dev->active_scan_mask;
  	if (!indio_dev->available_scan_masks)
  		indio_dev->active_scan_mask = NULL;
  
  	if (remove_buffer)
  		iio_buffer_deactivate(remove_buffer);
  	if (insert_buffer)
  		iio_buffer_activate(indio_dev, insert_buffer);
  
  	/* If no buffers in list, we are done */
  	if (list_empty(&indio_dev->buffer_list)) {
  		indio_dev->currentmode = INDIO_DIRECT_MODE;
  		if (indio_dev->available_scan_masks == NULL)
  			kfree(old_mask);
  		return 0;
  	}
  
  	/* What scan mask do we actually have? */
  	compound_mask = kcalloc(BITS_TO_LONGS(indio_dev->masklength),
  				sizeof(long), GFP_KERNEL);
  	if (compound_mask == NULL) {
  		if (indio_dev->available_scan_masks == NULL)
  			kfree(old_mask);
  		return -ENOMEM;
  	}
  	indio_dev->scan_timestamp = 0;
  
  	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
  		bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
  			  indio_dev->masklength);
  		indio_dev->scan_timestamp |= buffer->scan_timestamp;
  	}
  	if (indio_dev->available_scan_masks) {
  		indio_dev->active_scan_mask =
  			iio_scan_mask_match(indio_dev->available_scan_masks,
  					    indio_dev->masklength,
  					    compound_mask);
  		if (indio_dev->active_scan_mask == NULL) {
  			/*
  			 * Roll back.
  			 * Note can only occur when adding a buffer.
  			 */
  			iio_buffer_deactivate(insert_buffer);
  			if (old_mask) {
  				indio_dev->active_scan_mask = old_mask;
  				success = -EINVAL;
  			}
  			else {
  				kfree(compound_mask);
  				ret = -EINVAL;
  				goto error_ret;
  			}
  		}
  	} else {
  		indio_dev->active_scan_mask = compound_mask;
  	}
  
  	iio_update_demux(indio_dev);
  
  	/* Wind up again */
  	if (indio_dev->setup_ops->preenable) {
  		ret = indio_dev->setup_ops->preenable(indio_dev);
  		if (ret) {
  			printk(KERN_ERR
  			       "Buffer not started: buffer preenable failed (%d)
  ", ret);
  			goto error_remove_inserted;
  		}
  	}
  	indio_dev->scan_bytes =
  		iio_compute_scan_bytes(indio_dev,
  				       indio_dev->active_scan_mask,
  				       indio_dev->scan_timestamp);
  	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
  		iio_buffer_update_bytes_per_datum(indio_dev, buffer);
  		if (buffer->access->request_update) {
  			ret = buffer->access->request_update(buffer);
  			if (ret) {
  				printk(KERN_INFO
  				       "Buffer not started: buffer parameter update failed (%d)
  ", ret);
  				goto error_run_postdisable;
  			}
  		}
  	}
  	if (indio_dev->info->update_scan_mode) {
  		ret = indio_dev->info
  			->update_scan_mode(indio_dev,
  					   indio_dev->active_scan_mask);
  		if (ret < 0) {
  			printk(KERN_INFO "Buffer not started: update scan mode failed (%d)
  ", ret);
  			goto error_run_postdisable;
  		}
  	}
  	/* Definitely possible for devices to support both of these. */
  	if (indio_dev->modes & INDIO_BUFFER_TRIGGERED) {
  		if (!indio_dev->trig) {
  			printk(KERN_INFO "Buffer not started: no trigger
  ");
  			ret = -EINVAL;
  			/* Can only occur on first buffer */
  			goto error_run_postdisable;
  		}
  		indio_dev->currentmode = INDIO_BUFFER_TRIGGERED;
  	} else if (indio_dev->modes & INDIO_BUFFER_HARDWARE) {
  		indio_dev->currentmode = INDIO_BUFFER_HARDWARE;
  	} else { /* Should never be reached */
  		ret = -EINVAL;
  		goto error_run_postdisable;
  	}
  
  	if (indio_dev->setup_ops->postenable) {
  		ret = indio_dev->setup_ops->postenable(indio_dev);
  		if (ret) {
  			printk(KERN_INFO
  			       "Buffer not started: postenable failed (%d)
  ", ret);
  			indio_dev->currentmode = INDIO_DIRECT_MODE;
  			if (indio_dev->setup_ops->postdisable)
  				indio_dev->setup_ops->postdisable(indio_dev);
  			goto error_disable_all_buffers;
  		}
  	}
  
  	if (indio_dev->available_scan_masks)
  		kfree(compound_mask);
  	else
  		kfree(old_mask);
  
  	return success;
  
  error_disable_all_buffers:
  	indio_dev->currentmode = INDIO_DIRECT_MODE;
  error_run_postdisable:
  	if (indio_dev->setup_ops->postdisable)
  		indio_dev->setup_ops->postdisable(indio_dev);
  error_remove_inserted:
  
  	if (insert_buffer)
  		iio_buffer_deactivate(insert_buffer);
  	indio_dev->active_scan_mask = old_mask;
  	kfree(compound_mask);
  error_ret:
  
  	return ret;
  }
  
  int iio_update_buffers(struct iio_dev *indio_dev,
  		       struct iio_buffer *insert_buffer,
  		       struct iio_buffer *remove_buffer)
  {
  	int ret;
  
  	if (insert_buffer == remove_buffer)
  		return 0;
  
  	mutex_lock(&indio_dev->info_exist_lock);
  	mutex_lock(&indio_dev->mlock);
  
  	if (insert_buffer && iio_buffer_is_active(insert_buffer))
  		insert_buffer = NULL;
  
  	if (remove_buffer && !iio_buffer_is_active(remove_buffer))
  		remove_buffer = NULL;
  
  	if (!insert_buffer && !remove_buffer) {
  		ret = 0;
  		goto out_unlock;
  	}
  
  	if (indio_dev->info == NULL) {
  		ret = -ENODEV;
  		goto out_unlock;
  	}
  
  	ret = __iio_update_buffers(indio_dev, insert_buffer, remove_buffer);
  
  out_unlock:
  	mutex_unlock(&indio_dev->mlock);
  	mutex_unlock(&indio_dev->info_exist_lock);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(iio_update_buffers);
  
  ssize_t iio_buffer_store_enable(struct device *dev,
  				struct device_attribute *attr,
  				const char *buf,
  				size_t len)
  {
  	int ret;
  	bool requested_state;
  	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
  	bool inlist;
  
  	ret = strtobool(buf, &requested_state);
  	if (ret < 0)
  		return ret;
  
  	mutex_lock(&indio_dev->mlock);
  
  	/* Find out if it is in the list */
  	inlist = iio_buffer_is_active(indio_dev->buffer);
  	/* Already in desired state */
  	if (inlist == requested_state)
  		goto done;
  
  	if (requested_state)
  		ret = __iio_update_buffers(indio_dev,
  					 indio_dev->buffer, NULL);
  	else
  		ret = __iio_update_buffers(indio_dev,
  					 NULL, indio_dev->buffer);
  
  	if (ret < 0)
  		goto done;
  done:
  	mutex_unlock(&indio_dev->mlock);
  	return (ret < 0) ? ret : len;
  }
  EXPORT_SYMBOL(iio_buffer_store_enable);
  
  /**
   * iio_validate_scan_mask_onehot() - Validates that exactly one channel is selected
   * @indio_dev: the iio device
   * @mask: scan mask to be checked
   *
   * Return true if exactly one bit is set in the scan mask, false otherwise. It
   * can be used for devices where only one channel can be active for sampling at
   * a time.
   */
  bool iio_validate_scan_mask_onehot(struct iio_dev *indio_dev,
  	const unsigned long *mask)
  {
  	return bitmap_weight(mask, indio_dev->masklength) == 1;
  }
  EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
  
  static bool iio_validate_scan_mask(struct iio_dev *indio_dev,
  	const unsigned long *mask)
  {
  	if (!indio_dev->setup_ops->validate_scan_mask)
  		return true;
  
  	return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
  }
  
  /**
   * iio_scan_mask_set() - set particular bit in the scan mask
   * @indio_dev: the iio device
   * @buffer: the buffer whose scan mask we are interested in
   * @bit: the bit to be set.
   *
   * Note that at this point we have no way of knowing what other
   * buffers might request, hence this code only verifies that the
   * individual buffers request is plausible.
   */
  int iio_scan_mask_set(struct iio_dev *indio_dev,
  		      struct iio_buffer *buffer, int bit)
  {
  	const unsigned long *mask;
  	unsigned long *trialmask;
  
  	trialmask = kmalloc(sizeof(*trialmask)*
  			    BITS_TO_LONGS(indio_dev->masklength),
  			    GFP_KERNEL);
  
  	if (trialmask == NULL)
  		return -ENOMEM;
  	if (!indio_dev->masklength) {
  		WARN_ON("Trying to set scanmask prior to registering buffer
  ");
  		goto err_invalid_mask;
  	}
  	bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
  	set_bit(bit, trialmask);
  
  	if (!iio_validate_scan_mask(indio_dev, trialmask))
  		goto err_invalid_mask;
  
  	if (indio_dev->available_scan_masks) {
  		mask = iio_scan_mask_match(indio_dev->available_scan_masks,
  					   indio_dev->masklength,
  					   trialmask);
  		if (!mask)
  			goto err_invalid_mask;
  	}
  	bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
  
  	kfree(trialmask);
  
  	return 0;
  
  err_invalid_mask:
  	kfree(trialmask);
  	return -EINVAL;
  }
  EXPORT_SYMBOL_GPL(iio_scan_mask_set);
  
  int iio_scan_mask_query(struct iio_dev *indio_dev,
  			struct iio_buffer *buffer, int bit)
  {
  	if (bit > indio_dev->masklength)
  		return -EINVAL;
  
  	if (!buffer->scan_mask)
  		return 0;
  
  	/* Ensure return value is 0 or 1. */
  	return !!test_bit(bit, buffer->scan_mask);
  };
  EXPORT_SYMBOL_GPL(iio_scan_mask_query);
  
  /**
   * struct iio_demux_table() - table describing demux memcpy ops
   * @from:	index to copy from
   * @to:		index to copy to
   * @length:	how many bytes to copy
   * @l:		list head used for management
   */
  struct iio_demux_table {
  	unsigned from;
  	unsigned to;
  	unsigned length;
  	struct list_head l;
  };
  
  static const void *iio_demux(struct iio_buffer *buffer,
  				 const void *datain)
  {
  	struct iio_demux_table *t;
  
  	if (list_empty(&buffer->demux_list))
  		return datain;
  	list_for_each_entry(t, &buffer->demux_list, l)
  		memcpy(buffer->demux_bounce + t->to,
  		       datain + t->from, t->length);
  
  	return buffer->demux_bounce;
  }
  
  static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
  {
  	const void *dataout = iio_demux(buffer, data);
  
  	return buffer->access->store_to(buffer, dataout);
  }
  
  static void iio_buffer_demux_free(struct iio_buffer *buffer)
  {
  	struct iio_demux_table *p, *q;
  	list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
  		list_del(&p->l);
  		kfree(p);
  	}
  }
  
  
  int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
  {
  	int ret;
  	struct iio_buffer *buf;
  
  	list_for_each_entry(buf, &indio_dev->buffer_list, buffer_list) {
  		ret = iio_push_to_buffer(buf, data);
  		if (ret < 0)
  			return ret;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(iio_push_to_buffers);
  
  static int iio_buffer_update_demux(struct iio_dev *indio_dev,
  				   struct iio_buffer *buffer)
  {
  	const struct iio_chan_spec *ch;
  	int ret, in_ind = -1, out_ind, length;
  	unsigned in_loc = 0, out_loc = 0;
  	struct iio_demux_table *p;
  
  	/* Clear out any old demux */
  	iio_buffer_demux_free(buffer);
  	kfree(buffer->demux_bounce);
  	buffer->demux_bounce = NULL;
  
  	/* First work out which scan mode we will actually have */
  	if (bitmap_equal(indio_dev->active_scan_mask,
  			 buffer->scan_mask,
  			 indio_dev->masklength))
  		return 0;
  
  	/* Now we have the two masks, work from least sig and build up sizes */
  	for_each_set_bit(out_ind,
  			 buffer->scan_mask,
  			 indio_dev->masklength) {
  		in_ind = find_next_bit(indio_dev->active_scan_mask,
  				       indio_dev->masklength,
  				       in_ind + 1);
  		while (in_ind != out_ind) {
  			in_ind = find_next_bit(indio_dev->active_scan_mask,
  					       indio_dev->masklength,
  					       in_ind + 1);
  			ch = iio_find_channel_from_si(indio_dev, in_ind);
  			length = ch->scan_type.storagebits/8;
  			/* Make sure we are aligned */
  			in_loc += length;
  			if (in_loc % length)
  				in_loc += length - in_loc % length;
  		}
  		p = kmalloc(sizeof(*p), GFP_KERNEL);
  		if (p == NULL) {
  			ret = -ENOMEM;
  			goto error_clear_mux_table;
  		}
  		ch = iio_find_channel_from_si(indio_dev, in_ind);
  		length = ch->scan_type.storagebits/8;
  		if (out_loc % length)
  			out_loc += length - out_loc % length;
  		if (in_loc % length)
  			in_loc += length - in_loc % length;
  		p->from = in_loc;
  		p->to = out_loc;
  		p->length = length;
  		list_add_tail(&p->l, &buffer->demux_list);
  		out_loc += length;
  		in_loc += length;
  	}
  	/* Relies on scan_timestamp being last */
  	if (buffer->scan_timestamp) {
  		p = kmalloc(sizeof(*p), GFP_KERNEL);
  		if (p == NULL) {
  			ret = -ENOMEM;
  			goto error_clear_mux_table;
  		}
  		ch = iio_find_channel_from_si(indio_dev,
  			indio_dev->scan_index_timestamp);
  		length = ch->scan_type.storagebits/8;
  		if (out_loc % length)
  			out_loc += length - out_loc % length;
  		if (in_loc % length)
  			in_loc += length - in_loc % length;
  		p->from = in_loc;
  		p->to = out_loc;
  		p->length = length;
  		list_add_tail(&p->l, &buffer->demux_list);
  		out_loc += length;
  		in_loc += length;
  	}
  	buffer->demux_bounce = kzalloc(out_loc, GFP_KERNEL);
  	if (buffer->demux_bounce == NULL) {
  		ret = -ENOMEM;
  		goto error_clear_mux_table;
  	}
  	return 0;
  
  error_clear_mux_table:
  	iio_buffer_demux_free(buffer);
  
  	return ret;
  }
  
  int iio_update_demux(struct iio_dev *indio_dev)
  {
  	struct iio_buffer *buffer;
  	int ret;
  
  	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
  		ret = iio_buffer_update_demux(indio_dev, buffer);
  		if (ret < 0)
  			goto error_clear_mux_table;
  	}
  	return 0;
  
  error_clear_mux_table:
  	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
  		iio_buffer_demux_free(buffer);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(iio_update_demux);
  
  /**
   * iio_buffer_release() - Free a buffer's resources
   * @ref: Pointer to the kref embedded in the iio_buffer struct
   *
   * This function is called when the last reference to the buffer has been
   * dropped. It will typically free all resources allocated by the buffer. Do not
   * call this function manually, always use iio_buffer_put() when done using a
   * buffer.
   */
  static void iio_buffer_release(struct kref *ref)
  {
  	struct iio_buffer *buffer = container_of(ref, struct iio_buffer, ref);
  
  	buffer->access->release(buffer);
  }
  
  /**
   * iio_buffer_get() - Grab a reference to the buffer
   * @buffer: The buffer to grab a reference for, may be NULL
   *
   * Returns the pointer to the buffer that was passed into the function.
   */
  struct iio_buffer *iio_buffer_get(struct iio_buffer *buffer)
  {
  	if (buffer)
  		kref_get(&buffer->ref);
  
  	return buffer;
  }
  EXPORT_SYMBOL_GPL(iio_buffer_get);
  
  /**
   * iio_buffer_put() - Release the reference to the buffer
   * @buffer: The buffer to release the reference for, may be NULL
   */
  void iio_buffer_put(struct iio_buffer *buffer)
  {
  	if (buffer)
  		kref_put(&buffer->ref, iio_buffer_release);
  }
  EXPORT_SYMBOL_GPL(iio_buffer_put);