1 files changed, 755 insertions, 0 deletions

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
new file mode 100644
index 000000000000..ac185b8694bd
--- /dev/null
+++ b/drivers/iio/industrialio-buffer.c
@@ -0,0 +1,755 @@
+/* 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/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",
+};
+
+/**
+ * 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;
+
+	if (!rb || !rb->access->read_first_n)
+		return -EINVAL;
+	return rb->access->read_first_n(rb, n, buf);
+}
+
+/**
+ * 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;
+
+	poll_wait(filp, &rb->pollq, wait);
+	if (rb->stufftoread)
+		return POLLIN | POLLRDNORM;
+	/* need a way of knowing if there may be enough data... */
+	return 0;
+}
+
+void iio_buffer_init(struct iio_buffer *buffer)
+{
+	INIT_LIST_HEAD(&buffer->demux_list);
+	init_waitqueue_head(&buffer->pollq);
+}
+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\n", 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\n",
+		       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);
+
+	ret = test_bit(to_iio_dev_attr(attr)->address,
+		       indio_dev->buffer->scan_mask);
+
+	return sprintf(buf, "%d\n", 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_enabled(indio_dev)) {
+		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\n", 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_enabled(indio_dev)) {
+		ret = -EBUSY;
+		goto error_ret;
+	}
+	indio_dev->buffer->scan_timestamp = state;
+	indio_dev->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,
+				     0,
+				     &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);
+	attrcount++;
+	ret = attrcount;
+error_ret:
+	return ret;
+}
+
+static void iio_buffer_remove_and_free_scan_dev_attr(struct iio_dev *indio_dev,
+						     struct iio_dev_attr *p)
+{
+	kfree(p->dev_attr.attr.name);
+	kfree(p);
+}
+
+static void __iio_buffer_attr_cleanup(struct iio_dev *indio_dev)
+{
+	struct iio_dev_attr *p, *n;
+	struct iio_buffer *buffer = indio_dev->buffer;
+
+	list_for_each_entry_safe(p, n,
+				 &buffer->scan_el_dev_attr_list, l)
+		iio_buffer_remove_and_free_scan_dev_attr(indio_dev, p);
+}
+
+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++) {
+			/* Establish necessary mask length */
+			if (channels[i].scan_index >
+			    (int)indio_dev->masklength - 1)
+				indio_dev->masklength
+					= indio_dev->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_buffer_attr_cleanup(indio_dev);
+
+	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_buffer_attr_cleanup(indio_dev);
+}
+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\n",
+			       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)
+{
+	int ret;
+	ulong val;
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_buffer *buffer = indio_dev->buffer;
+
+	ret = strict_strtoul(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_enabled(indio_dev)) {
+		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_store_enable(struct device *dev,
+				struct device_attribute *attr,
+				const char *buf,
+				size_t len)
+{
+	int ret;
+	bool requested_state, current_state;
+	int previous_mode;
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_buffer *buffer = indio_dev->buffer;
+
+	mutex_lock(&indio_dev->mlock);
+	previous_mode = indio_dev->currentmode;
+	requested_state = !(buf[0] == '0');
+	current_state = iio_buffer_enabled(indio_dev);
+	if (current_state == requested_state) {
+		printk(KERN_INFO "iio-buffer, current state requested again\n");
+		goto done;
+	}
+	if (requested_state) {
+		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\n");
+				goto error_ret;
+			}
+		}
+		if (buffer->access->request_update) {
+			ret = buffer->access->request_update(buffer);
+			if (ret) {
+				printk(KERN_INFO
+				       "Buffer not started:"
+				       "buffer parameter update failed\n");
+				goto error_ret;
+			}
+		}
+		/* 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\n");
+				ret = -EINVAL;
+				goto error_ret;
+			}
+			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_ret;
+		}
+
+		if (indio_dev->setup_ops->postenable) {
+			ret = indio_dev->setup_ops->postenable(indio_dev);
+			if (ret) {
+				printk(KERN_INFO
+				       "Buffer not started:"
+				       "postenable failed\n");
+				indio_dev->currentmode = previous_mode;
+				if (indio_dev->setup_ops->postdisable)
+					indio_dev->setup_ops->
+						postdisable(indio_dev);
+				goto error_ret;
+			}
+		}
+	} else {
+		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;
+		}
+	}
+done:
+	mutex_unlock(&indio_dev->mlock);
+	return len;
+
+error_ret:
+	mutex_unlock(&indio_dev->mlock);
+	return ret;
+}
+EXPORT_SYMBOL(iio_buffer_store_enable);
+
+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\n", iio_buffer_enabled(indio_dev));
+}
+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 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;
+}
+
+int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer = indio_dev->buffer;
+	dev_dbg(&indio_dev->dev, "%s\n", __func__);
+
+	/* How much space will the demuxed element take? */
+	indio_dev->scan_bytes =
+		iio_compute_scan_bytes(indio_dev, buffer->scan_mask,
+				       buffer->scan_timestamp);
+	buffer->access->set_bytes_per_datum(buffer, indio_dev->scan_bytes);
+
+	/* What scan mask do we actually have ?*/
+	if (indio_dev->available_scan_masks)
+		indio_dev->active_scan_mask =
+			iio_scan_mask_match(indio_dev->available_scan_masks,
+					    indio_dev->masklength,
+					    buffer->scan_mask);
+	else
+		indio_dev->active_scan_mask = buffer->scan_mask;
+	iio_update_demux(indio_dev);
+
+	if (indio_dev->info->update_scan_mode)
+		return indio_dev->info
+			->update_scan_mode(indio_dev,
+					   indio_dev->active_scan_mask);
+	return 0;
+}
+EXPORT_SYMBOL(iio_sw_buffer_preenable);
+
+/**
+ * iio_scan_mask_set() - set particular bit in the scan mask
+ * @buffer: the buffer whose scan mask we are interested in
+ * @bit: the bit to be set.
+ **/
+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\n");
+		kfree(trialmask);
+		return -EINVAL;
+	}
+	bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
+	set_bit(bit, trialmask);
+
+	if (indio_dev->available_scan_masks) {
+		mask = iio_scan_mask_match(indio_dev->available_scan_masks,
+					   indio_dev->masklength,
+					   trialmask);
+		if (!mask) {
+			kfree(trialmask);
+			return -EINVAL;
+		}
+	}
+	bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
+
+	kfree(trialmask);
+
+	return 0;
+};
+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;
+
+	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 unsigned char *iio_demux(struct iio_buffer *buffer,
+				 unsigned char *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;
+}
+
+int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
+		       s64 timestamp)
+{
+	unsigned char *dataout = iio_demux(buffer, data);
+
+	return buffer->access->store_to(buffer, dataout, timestamp);
+}
+EXPORT_SYMBOL_GPL(iio_push_to_buffer);
+
+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_update_demux(struct iio_dev *indio_dev)
+{
+	const struct iio_chan_spec *ch;
+	struct iio_buffer *buffer = indio_dev->buffer;
+	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,
+			 indio_dev->active_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;
+}
+EXPORT_SYMBOL_GPL(iio_update_demux);