--- zzzz-none-000/linux-3.10.107/drivers/iio/industrialio-buffer.c	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/drivers/iio/industrialio-buffer.c	2021-02-04 17:41:59.000000000 +0000
@@ -20,6 +20,7 @@
 #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"
@@ -31,37 +32,141 @@
 	[IIO_LE] = "le",
 };
 
-static bool iio_buffer_is_active(struct iio_dev *indio_dev,
-				 struct iio_buffer *buf)
+static bool iio_buffer_is_active(struct iio_buffer *buf)
 {
-	struct list_head *p;
+	return !list_empty(&buf->buffer_list);
+}
+
+static size_t iio_buffer_data_available(struct iio_buffer *buf)
+{
+	return buf->access->data_available(buf);
+}
+
+static int iio_buffer_flush_hwfifo(struct iio_dev *indio_dev,
+				   struct iio_buffer *buf, size_t required)
+{
+	if (!indio_dev->info->hwfifo_flush_to_buffer)
+		return -ENODEV;
+
+	return indio_dev->info->hwfifo_flush_to_buffer(indio_dev, required);
+}
+
+static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf,
+			     size_t to_wait, int to_flush)
+{
+	size_t avail;
+	int flushed = 0;
 
-	list_for_each(p, &indio_dev->buffer_list)
-		if (p == &buf->buffer_list)
-			return true;
+	/* wakeup if the device was unregistered */
+	if (!indio_dev->info)
+		return true;
+
+	/* drain the buffer if it was disabled */
+	if (!iio_buffer_is_active(buf)) {
+		to_wait = min_t(size_t, to_wait, 1);
+		to_flush = 0;
+	}
+
+	avail = iio_buffer_data_available(buf);
+
+	if (avail >= to_wait) {
+		/* force a flush for non-blocking reads */
+		if (!to_wait && avail < to_flush)
+			iio_buffer_flush_hwfifo(indio_dev, buf,
+						to_flush - avail);
+		return true;
+	}
+
+	if (to_flush)
+		flushed = iio_buffer_flush_hwfifo(indio_dev, buf,
+						  to_wait - avail);
+	if (flushed <= 0)
+		return false;
+
+	if (avail + flushed >= to_wait)
+		return true;
 
 	return false;
 }
 
 /**
  * iio_buffer_read_first_n_outer() - chrdev read for buffer access
+ * @filp:	File structure pointer for the char device
+ * @buf:	Destination buffer for iio buffer read
+ * @n:		First n bytes to read
+ * @f_ps:	Long offset provided by the user as a seek position
  *
  * This function relies on all buffer implementations having an
  * iio_buffer as their first element.
+ *
+ * Return: negative values corresponding to error codes or ret != 0
+ *	   for ending the reading activity
  **/
 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;
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	size_t datum_size;
+	size_t to_wait;
+	int ret = 0;
+
+	if (!indio_dev->info)
+		return -ENODEV;
 
 	if (!rb || !rb->access->read_first_n)
 		return -EINVAL;
-	return rb->access->read_first_n(rb, n, buf);
+
+	datum_size = rb->bytes_per_datum;
+
+	/*
+	 * If datum_size is 0 there will never be anything to read from the
+	 * buffer, so signal end of file now.
+	 */
+	if (!datum_size)
+		return 0;
+
+	if (filp->f_flags & O_NONBLOCK)
+		to_wait = 0;
+	else
+		to_wait = min_t(size_t, n / datum_size, rb->watermark);
+
+	add_wait_queue(&rb->pollq, &wait);
+	do {
+		if (!indio_dev->info) {
+			ret = -ENODEV;
+			break;
+		}
+
+		if (!iio_buffer_ready(indio_dev, rb, to_wait, n / datum_size)) {
+			if (signal_pending(current)) {
+				ret = -ERESTARTSYS;
+				break;
+			}
+
+			wait_woken(&wait, TASK_INTERRUPTIBLE,
+				   MAX_SCHEDULE_TIMEOUT);
+			continue;
+		}
+
+		ret = rb->access->read_first_n(rb, n, buf);
+		if (ret == 0 && (filp->f_flags & O_NONBLOCK))
+			ret = -EAGAIN;
+	} while (ret == 0);
+	remove_wait_queue(&rb->pollq, &wait);
+
+	return ret;
 }
 
 /**
  * iio_buffer_poll() - poll the buffer to find out if it has data
+ * @filp:	File structure pointer for device access
+ * @wait:	Poll table structure pointer for which the driver adds
+ *		a wait queue
+ *
+ * Return: (POLLIN | POLLRDNORM) if data is available for reading
+ *	   or 0 for other cases
  */
 unsigned int iio_buffer_poll(struct file *filp,
 			     struct poll_table_struct *wait)
@@ -69,17 +174,37 @@
 	struct iio_dev *indio_dev = filp->private_data;
 	struct iio_buffer *rb = indio_dev->buffer;
 
+	if (!indio_dev->info)
+		return 0;
+
 	poll_wait(filp, &rb->pollq, wait);
-	if (rb->stufftoread)
+	if (iio_buffer_ready(indio_dev, rb, rb->watermark, 0))
 		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);
+	buffer->watermark = 1;
 }
 EXPORT_SYMBOL(iio_buffer_init);
 
@@ -104,7 +229,16 @@
 		type = IIO_BE;
 #endif
 	}
-	return sprintf(buf, "%s:%c%d/%d>>%u\n",
+	if (this_attr->c->scan_type.repeat > 1)
+		return sprintf(buf, "%s:%c%d/%dX%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.repeat,
+		       this_attr->c->scan_type.shift);
+		else
+			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,
@@ -126,6 +260,86 @@
 	return sprintf(buf, "%d\n", ret);
 }
 
+/* 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,
+					  bool strict)
+{
+	if (bitmap_empty(mask, masklength))
+		return NULL;
+	while (*av_masks) {
+		if (strict) {
+			if (bitmap_equal(mask, av_masks, masklength))
+				return av_masks;
+		} else {
+			if (bitmap_subset(mask, av_masks, masklength))
+				return av_masks;
+		}
+		av_masks += BITS_TO_LONGS(masklength);
+	}
+	return NULL;
+}
+
+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.
+ */
+static 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(1, "Trying to set scanmask prior to registering buffer\n");
+		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, false);
+		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;
+}
+
 static int iio_scan_mask_clear(struct iio_buffer *buffer, int bit)
 {
 	clear_bit(bit, buffer->scan_mask);
@@ -147,7 +361,7 @@
 	if (ret < 0)
 		return ret;
 	mutex_lock(&indio_dev->mlock);
-	if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+	if (iio_buffer_is_active(indio_dev->buffer)) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
@@ -193,7 +407,7 @@
 		return ret;
 
 	mutex_lock(&indio_dev->mlock);
-	if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+	if (iio_buffer_is_active(indio_dev->buffer)) {
 		ret = -EBUSY;
 		goto error_ret;
 	}
@@ -215,11 +429,11 @@
 				     &iio_show_scan_index,
 				     NULL,
 				     0,
-				     0,
+				     IIO_SEPARATE,
 				     &indio_dev->dev,
 				     &buffer->scan_el_dev_attr_list);
 	if (ret)
-		goto error_ret;
+		return ret;
 	attrcount++;
 	ret = __iio_add_chan_devattr("type",
 				     chan,
@@ -230,7 +444,7 @@
 				     &indio_dev->dev,
 				     &buffer->scan_el_dev_attr_list);
 	if (ret)
-		goto error_ret;
+		return ret;
 	attrcount++;
 	if (chan->type != IIO_TIMESTAMP)
 		ret = __iio_add_chan_devattr("en",
@@ -250,138 +464,26 @@
 					     0,
 					     &indio_dev->dev,
 					     &buffer->scan_el_dev_attr_list);
+	if (ret)
+		return ret;
 	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++) {
-			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_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)
+static 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;
+	return sprintf(buf, "%d\n", buffer->length);
 }
-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)
+static 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;
@@ -392,52 +494,36 @@
 	if (ret)
 		return ret;
 
-	if (buffer->access->get_length)
-		if (val == buffer->access->get_length(buffer))
-			return len;
+	if (val == buffer->length)
+		return len;
 
 	mutex_lock(&indio_dev->mlock);
-	if (iio_buffer_is_active(indio_dev, indio_dev->buffer)) {
+	if (iio_buffer_is_active(indio_dev->buffer)) {
 		ret = -EBUSY;
 	} else {
-		if (buffer->access->set_length)
-			buffer->access->set_length(buffer, val);
+		buffer->access->set_length(buffer, val);
 		ret = 0;
 	}
+	if (ret)
+		goto out;
+	if (buffer->length && buffer->length < buffer->watermark)
+		buffer->watermark = buffer->length;
+out:
 	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)
+static 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_is_active(indio_dev,
-					    indio_dev->buffer));
+	return sprintf(buf, "%d\n", 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 long *mask,
-				  bool timestamp)
+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;
@@ -447,191 +533,391 @@
 	for_each_set_bit(i, mask,
 			 indio_dev->masklength) {
 		ch = iio_find_channel_from_si(indio_dev, i);
-		length = ch->scan_type.storagebits / 8;
+		if (ch->scan_type.repeat > 1)
+			length = ch->scan_type.storagebits / 8 *
+				ch->scan_type.repeat;
+		else
+			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;
+		if (ch->scan_type.repeat > 1)
+			length = ch->scan_type.storagebits / 8 *
+				ch->scan_type.repeat;
+		else
+			length = ch->scan_type.storagebits / 8;
 		bytes = ALIGN(bytes, length);
 		bytes += length;
 	}
 	return bytes;
 }
 
-int iio_update_buffers(struct iio_dev *indio_dev,
-		       struct iio_buffer *insert_buffer,
-		       struct iio_buffer *remove_buffer)
+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);
+	wake_up_interruptible(&buffer->pollq);
+	iio_buffer_put(buffer);
+}
+
+static void iio_buffer_deactivate_all(struct iio_dev *indio_dev)
+{
+	struct iio_buffer *buffer, *_buffer;
+
+	list_for_each_entry_safe(buffer, _buffer,
+			&indio_dev->buffer_list, buffer_list)
+		iio_buffer_deactivate(buffer);
+}
+
+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_buffer_request_update(struct iio_dev *indio_dev,
+	struct iio_buffer *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;
+	iio_buffer_update_bytes_per_datum(indio_dev, buffer);
+	if (buffer->access->request_update) {
+		ret = buffer->access->request_update(buffer);
+		if (ret) {
+			dev_dbg(&indio_dev->dev,
+			       "Buffer not started: buffer parameter update failed (%d)\n",
+				ret);
+			return ret;
 		}
 	}
-	/* Keep a copy of current setup to allow roll back */
-	old_mask = indio_dev->active_scan_mask;
+
+	return 0;
+}
+
+static void iio_free_scan_mask(struct iio_dev *indio_dev,
+	const unsigned long *mask)
+{
+	/* If the mask is dynamically allocated free it, otherwise do nothing */
 	if (!indio_dev->available_scan_masks)
-		indio_dev->active_scan_mask = NULL;
+		kfree(mask);
+}
+
+struct iio_device_config {
+	unsigned int mode;
+	const unsigned long *scan_mask;
+	unsigned int scan_bytes;
+	bool scan_timestamp;
+};
+
+static int iio_verify_update(struct iio_dev *indio_dev,
+	struct iio_buffer *insert_buffer, struct iio_buffer *remove_buffer,
+	struct iio_device_config *config)
+{
+	unsigned long *compound_mask;
+	const unsigned long *scan_mask;
+	bool strict_scanmask = false;
+	struct iio_buffer *buffer;
+	bool scan_timestamp;
+	unsigned int modes;
+
+	memset(config, 0, sizeof(*config));
+
+	/*
+	 * If there is just one buffer and we are removing it there is nothing
+	 * to verify.
+	 */
+	if (remove_buffer && !insert_buffer &&
+		list_is_singular(&indio_dev->buffer_list))
+			return 0;
+
+	modes = indio_dev->modes;
+
+	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
+		if (buffer == remove_buffer)
+			continue;
+		modes &= buffer->access->modes;
+	}
 
-	if (remove_buffer)
-		list_del(&remove_buffer->buffer_list);
 	if (insert_buffer)
-		list_add(&insert_buffer->buffer_list, &indio_dev->buffer_list);
+		modes &= insert_buffer->access->modes;
 
-	/* 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;
+	/* Definitely possible for devices to support both of these. */
+	if ((modes & INDIO_BUFFER_TRIGGERED) && indio_dev->trig) {
+		config->mode = INDIO_BUFFER_TRIGGERED;
+	} else if (modes & INDIO_BUFFER_HARDWARE) {
+		/*
+		 * Keep things simple for now and only allow a single buffer to
+		 * be connected in hardware mode.
+		 */
+		if (insert_buffer && !list_empty(&indio_dev->buffer_list))
+			return -EINVAL;
+		config->mode = INDIO_BUFFER_HARDWARE;
+		strict_scanmask = true;
+	} else if (modes & INDIO_BUFFER_SOFTWARE) {
+		config->mode = INDIO_BUFFER_SOFTWARE;
+	} else {
+		/* Can only occur on first buffer */
+		if (indio_dev->modes & INDIO_BUFFER_TRIGGERED)
+			dev_dbg(&indio_dev->dev, "Buffer not started: no trigger\n");
+		return -EINVAL;
 	}
 
-	/* What scan mask do we actually have ?*/
+	/* 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);
+	if (compound_mask == NULL)
 		return -ENOMEM;
-	}
-	indio_dev->scan_timestamp = 0;
+
+	scan_timestamp = false;
 
 	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list) {
+		if (buffer == remove_buffer)
+			continue;
 		bitmap_or(compound_mask, compound_mask, buffer->scan_mask,
 			  indio_dev->masklength);
-		indio_dev->scan_timestamp |= buffer->scan_timestamp;
+		scan_timestamp |= buffer->scan_timestamp;
 	}
+
+	if (insert_buffer) {
+		bitmap_or(compound_mask, compound_mask,
+			  insert_buffer->scan_mask, indio_dev->masklength);
+		scan_timestamp |= insert_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.
-			 */
-			list_del(&insert_buffer->buffer_list);
-			indio_dev->active_scan_mask = old_mask;
-			success = -EINVAL;
-		}
+		scan_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
+				    indio_dev->masklength,
+				    compound_mask,
+				    strict_scanmask);
+		kfree(compound_mask);
+		if (scan_mask == NULL)
+			return -EINVAL;
 	} else {
-		indio_dev->active_scan_mask = compound_mask;
+	    scan_mask = compound_mask;
 	}
 
+	config->scan_bytes = iio_compute_scan_bytes(indio_dev,
+				    scan_mask, scan_timestamp);
+	config->scan_mask = scan_mask;
+	config->scan_timestamp = scan_timestamp;
+
+	return 0;
+}
+
+static int iio_enable_buffers(struct iio_dev *indio_dev,
+	struct iio_device_config *config)
+{
+	int ret;
+
+	indio_dev->active_scan_mask = config->scan_mask;
+	indio_dev->scan_timestamp = config->scan_timestamp;
+	indio_dev->scan_bytes = config->scan_bytes;
+
 	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\n");
-			goto error_remove_inserted;
+			dev_dbg(&indio_dev->dev,
+			       "Buffer not started: buffer preenable failed (%d)\n", ret);
+			goto err_undo_config;
 		}
 	}
-	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)
-		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_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 "update scan mode failed\n");
-			goto error_run_postdisable;
+			dev_dbg(&indio_dev->dev,
+				"Buffer not started: update scan mode failed (%d)\n",
+				ret);
+			goto err_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\n");
-			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;
-	}
+
+	indio_dev->currentmode = config->mode;
 
 	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 = INDIO_DIRECT_MODE;
-			if (indio_dev->setup_ops->postdisable)
-				indio_dev->setup_ops->postdisable(indio_dev);
-			goto error_disable_all_buffers;
+			dev_dbg(&indio_dev->dev,
+			       "Buffer not started: postenable failed (%d)\n", ret);
+			goto err_run_postdisable;
 		}
 	}
 
-	if (indio_dev->available_scan_masks)
-		kfree(compound_mask);
-	else
-		kfree(old_mask);
-
-	return success;
+	return 0;
 
-error_disable_all_buffers:
+err_run_postdisable:
 	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:
+err_undo_config:
+	indio_dev->active_scan_mask = NULL;
+
+	return ret;
+}
+
+static int iio_disable_buffers(struct iio_dev *indio_dev)
+{
+	int ret = 0;
+	int ret2;
+
+	/* Wind down existing buffers - iff there are any */
+	if (list_empty(&indio_dev->buffer_list))
+		return 0;
+
+	/*
+	 * If things go wrong at some step in disable we still need to continue
+	 * to perform the other steps, otherwise we leave the device in a
+	 * inconsistent state. We return the error code for the first error we
+	 * encountered.
+	 */
+
+	if (indio_dev->setup_ops->predisable) {
+		ret2 = indio_dev->setup_ops->predisable(indio_dev);
+		if (ret2 && !ret)
+			ret = ret2;
+	}
 
+	indio_dev->currentmode = INDIO_DIRECT_MODE;
+
+	if (indio_dev->setup_ops->postdisable) {
+		ret2 = indio_dev->setup_ops->postdisable(indio_dev);
+		if (ret2 && !ret)
+			ret = ret2;
+	}
+
+	iio_free_scan_mask(indio_dev, indio_dev->active_scan_mask);
+	indio_dev->active_scan_mask = NULL;
+
+	return ret;
+}
+
+static int __iio_update_buffers(struct iio_dev *indio_dev,
+		       struct iio_buffer *insert_buffer,
+		       struct iio_buffer *remove_buffer)
+{
+	struct iio_device_config new_config;
+	int ret;
+
+	ret = iio_verify_update(indio_dev, insert_buffer, remove_buffer,
+		&new_config);
+	if (ret)
+		return ret;
+
+	if (insert_buffer) {
+		ret = iio_buffer_request_update(indio_dev, insert_buffer);
+		if (ret)
+			goto err_free_config;
+	}
+
+	ret = iio_disable_buffers(indio_dev);
+	if (ret)
+		goto err_deactivate_all;
+
+	if (remove_buffer)
+		iio_buffer_deactivate(remove_buffer);
 	if (insert_buffer)
-		list_del(&insert_buffer->buffer_list);
-	indio_dev->active_scan_mask = old_mask;
-	kfree(compound_mask);
-error_ret:
+		iio_buffer_activate(indio_dev, insert_buffer);
+
+	/* If no buffers in list, we are done */
+	if (list_empty(&indio_dev->buffer_list))
+		return 0;
+
+	ret = iio_enable_buffers(indio_dev, &new_config);
+	if (ret)
+		goto err_deactivate_all;
+
+	return 0;
+
+err_deactivate_all:
+	/*
+	 * We've already verified that the config is valid earlier. If things go
+	 * wrong in either enable or disable the most likely reason is an IO
+	 * error from the device. In this case there is no good recovery
+	 * strategy. Just make sure to disable everything and leave the device
+	 * in a sane state.  With a bit of luck the device might come back to
+	 * life again later and userspace can try again.
+	 */
+	iio_buffer_deactivate_all(indio_dev);
+
+err_free_config:
+	iio_free_scan_mask(indio_dev, new_config.scan_mask);
+	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)
+void iio_disable_all_buffers(struct iio_dev *indio_dev)
+{
+	iio_disable_buffers(indio_dev);
+	iio_buffer_deactivate_all(indio_dev);
+}
+
+static 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);
-	struct iio_buffer *pbuf = indio_dev->buffer;
 	bool inlist;
 
 	ret = strtobool(buf, &requested_state);
@@ -641,118 +927,223 @@
 	mutex_lock(&indio_dev->mlock);
 
 	/* Find out if it is in the list */
-	inlist = iio_buffer_is_active(indio_dev, pbuf);
+	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,
+		ret = __iio_update_buffers(indio_dev,
 					 indio_dev->buffer, NULL);
 	else
-		ret = iio_update_buffers(indio_dev,
+		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);
 
-int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
-{
-	struct iio_buffer *buffer;
-	unsigned bytes;
-	dev_dbg(&indio_dev->dev, "%s\n", __func__);
+static const char * const iio_scan_elements_group_name = "scan_elements";
 
-	list_for_each_entry(buffer, &indio_dev->buffer_list, buffer_list)
-		if (buffer->access->set_bytes_per_datum) {
-			bytes = iio_compute_scan_bytes(indio_dev,
-						       buffer->scan_mask,
-						       buffer->scan_timestamp);
+static ssize_t iio_buffer_show_watermark(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;
 
-			buffer->access->set_bytes_per_datum(buffer, bytes);
-		}
-	return 0;
+	return sprintf(buf, "%u\n", buffer->watermark);
 }
-EXPORT_SYMBOL(iio_sw_buffer_preenable);
 
-/**
- * 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)
+static ssize_t iio_buffer_store_watermark(struct device *dev,
+					  struct device_attribute *attr,
+					  const char *buf,
+					  size_t len)
 {
-	return bitmap_weight(mask, indio_dev->masklength) == 1;
-}
-EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
+	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
+	struct iio_buffer *buffer = indio_dev->buffer;
+	unsigned int val;
+	int ret;
 
-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;
+	ret = kstrtouint(buf, 10, &val);
+	if (ret)
+		return ret;
+	if (!val)
+		return -EINVAL;
 
-	return indio_dev->setup_ops->validate_scan_mask(indio_dev, mask);
+	mutex_lock(&indio_dev->mlock);
+
+	if (val > buffer->length) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	if (iio_buffer_is_active(indio_dev->buffer)) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	buffer->watermark = val;
+
+	if (indio_dev->info->hwfifo_set_watermark)
+		indio_dev->info->hwfifo_set_watermark(indio_dev, val);
+out:
+	mutex_unlock(&indio_dev->mlock);
+
+	return ret ? ret : len;
 }
 
-/**
- * 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.
- *
- * 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)
+static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
+		   iio_buffer_write_length);
+static struct device_attribute dev_attr_length_ro = __ATTR(length,
+	S_IRUGO, iio_buffer_read_length, NULL);
+static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
+		   iio_buffer_show_enable, iio_buffer_store_enable);
+static DEVICE_ATTR(watermark, S_IRUGO | S_IWUSR,
+		   iio_buffer_show_watermark, iio_buffer_store_watermark);
+
+static struct attribute *iio_buffer_attrs[] = {
+	&dev_attr_length.attr,
+	&dev_attr_enable.attr,
+	&dev_attr_watermark.attr,
+};
+
+int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
 {
-	const unsigned long *mask;
-	unsigned long *trialmask;
+	struct iio_dev_attr *p;
+	struct attribute **attr;
+	struct iio_buffer *buffer = indio_dev->buffer;
+	int ret, i, attrn, attrcount, attrcount_orig = 0;
+	const struct iio_chan_spec *channels;
 
-	trialmask = kmalloc(sizeof(*trialmask)*
-			    BITS_TO_LONGS(indio_dev->masklength),
-			    GFP_KERNEL);
+	channels = indio_dev->channels;
+	if (channels) {
+		int ml = indio_dev->masklength;
 
-	if (trialmask == NULL)
+		for (i = 0; i < indio_dev->num_channels; i++)
+			ml = max(ml, channels[i].scan_index + 1);
+		indio_dev->masklength = ml;
+	}
+
+	if (!buffer)
+		return 0;
+
+	attrcount = 0;
+	if (buffer->attrs) {
+		while (buffer->attrs[attrcount] != NULL)
+			attrcount++;
+	}
+
+	attr = kcalloc(attrcount + ARRAY_SIZE(iio_buffer_attrs) + 1,
+		       sizeof(struct attribute *), GFP_KERNEL);
+	if (!attr)
 		return -ENOMEM;
-	if (!indio_dev->masklength) {
-		WARN_ON("trying to set scanmask prior to registering buffer\n");
-		goto err_invalid_mask;
+
+	memcpy(attr, iio_buffer_attrs, sizeof(iio_buffer_attrs));
+	if (!buffer->access->set_length)
+		attr[0] = &dev_attr_length_ro.attr;
+
+	if (buffer->attrs)
+		memcpy(&attr[ARRAY_SIZE(iio_buffer_attrs)], buffer->attrs,
+		       sizeof(struct attribute *) * attrcount);
+
+	attr[attrcount + ARRAY_SIZE(iio_buffer_attrs)] = NULL;
+
+	buffer->buffer_group.name = "buffer";
+	buffer->buffer_group.attrs = attr;
+
+	indio_dev->groups[indio_dev->groupcounter++] = &buffer->buffer_group;
+
+	if (buffer->scan_el_attrs != NULL) {
+		attr = buffer->scan_el_attrs->attrs;
+		while (*attr++ != NULL)
+			attrcount_orig++;
 	}
-	bitmap_copy(trialmask, buffer->scan_mask, indio_dev->masklength);
-	set_bit(bit, trialmask);
+	attrcount = attrcount_orig;
+	INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
+	channels = indio_dev->channels;
+	if (channels) {
+		/* new magic */
+		for (i = 0; i < indio_dev->num_channels; i++) {
+			if (channels[i].scan_index < 0)
+				continue;
 
-	if (!iio_validate_scan_mask(indio_dev, trialmask))
-		goto err_invalid_mask;
+			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;
+			}
+		}
+	}
 
-	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;
+	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;
 	}
-	bitmap_copy(buffer->scan_mask, trialmask, indio_dev->masklength);
+	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;
 
-	kfree(trialmask);
+	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;
 
-err_invalid_mask:
-	kfree(trialmask);
-	return -EINVAL;
+error_free_scan_mask:
+	kfree(buffer->scan_mask);
+error_cleanup_dynamic:
+	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
+	kfree(indio_dev->buffer->buffer_group.attrs);
+
+	return ret;
+}
+
+void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
+{
+	if (!indio_dev->buffer)
+		return;
+
+	kfree(indio_dev->buffer->scan_mask);
+	kfree(indio_dev->buffer->buffer_group.attrs);
+	kfree(indio_dev->buffer->scan_el_group.attrs);
+	iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
+}
+
+/**
+ * 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_scan_mask_set);
+EXPORT_SYMBOL_GPL(iio_validate_scan_mask_onehot);
 
 int iio_scan_mask_query(struct iio_dev *indio_dev,
 			struct iio_buffer *buffer, int bit)
@@ -769,7 +1160,7 @@
 EXPORT_SYMBOL_GPL(iio_scan_mask_query);
 
 /**
- * struct iio_demux_table() - table describing demux memcpy ops
+ * 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
@@ -782,8 +1173,8 @@
 	struct list_head l;
 };
 
-static unsigned char *iio_demux(struct iio_buffer *buffer,
-				 unsigned char *datain)
+static const void *iio_demux(struct iio_buffer *buffer,
+				 const void *datain)
 {
 	struct iio_demux_table *t;
 
@@ -796,11 +1187,21 @@
 	return buffer->demux_bounce;
 }
 
-static int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data)
+static int iio_push_to_buffer(struct iio_buffer *buffer, const void *data)
 {
-	unsigned char *dataout = iio_demux(buffer, data);
+	const void *dataout = iio_demux(buffer, data);
+	int ret;
+
+	ret = buffer->access->store_to(buffer, dataout);
+	if (ret)
+		return ret;
 
-	return buffer->access->store_to(buffer, dataout);
+	/*
+	 * We can't just test for watermark to decide if we wake the poll queue
+	 * because read may request less samples than the watermark.
+	 */
+	wake_up_interruptible_poll(&buffer->pollq, POLLIN | POLLRDNORM);
+	return 0;
 }
 
 static void iio_buffer_demux_free(struct iio_buffer *buffer)
@@ -813,7 +1214,7 @@
 }
 
 
-int iio_push_to_buffers(struct iio_dev *indio_dev, unsigned char *data)
+int iio_push_to_buffers(struct iio_dev *indio_dev, const void *data)
 {
 	int ret;
 	struct iio_buffer *buf;
@@ -828,13 +1229,34 @@
 }
 EXPORT_SYMBOL_GPL(iio_push_to_buffers);
 
+static int iio_buffer_add_demux(struct iio_buffer *buffer,
+	struct iio_demux_table **p, unsigned int in_loc, unsigned int out_loc,
+	unsigned int length)
+{
+
+	if (*p && (*p)->from + (*p)->length == in_loc &&
+		(*p)->to + (*p)->length == out_loc) {
+		(*p)->length += length;
+	} else {
+		*p = kmalloc(sizeof(**p), GFP_KERNEL);
+		if (*p == NULL)
+			return -ENOMEM;
+		(*p)->from = in_loc;
+		(*p)->to = out_loc;
+		(*p)->length = length;
+		list_add_tail(&(*p)->l, &buffer->demux_list);
+	}
+
+	return 0;
+}
+
 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;
+	struct iio_demux_table *p = NULL;
 
 	/* Clear out any old demux */
 	iio_buffer_demux_free(buffer);
@@ -859,48 +1281,42 @@
 					       indio_dev->masklength,
 					       in_ind + 1);
 			ch = iio_find_channel_from_si(indio_dev, in_ind);
-			length = ch->scan_type.storagebits/8;
+			if (ch->scan_type.repeat > 1)
+				length = ch->scan_type.storagebits / 8 *
+					ch->scan_type.repeat;
+			else
+				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;
+			in_loc = roundup(in_loc, length) + length;
 		}
 		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);
+		if (ch->scan_type.repeat > 1)
+			length = ch->scan_type.storagebits / 8 *
+				ch->scan_type.repeat;
+		else
+			length = ch->scan_type.storagebits / 8;
+		out_loc = roundup(out_loc, length);
+		in_loc = roundup(in_loc, length);
+		ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
+		if (ret)
+			goto error_clear_mux_table;
 		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);
+		if (ch->scan_type.repeat > 1)
+			length = ch->scan_type.storagebits / 8 *
+				ch->scan_type.repeat;
+		else
+			length = ch->scan_type.storagebits / 8;
+		out_loc = roundup(out_loc, length);
+		in_loc = roundup(in_loc, length);
+		ret = iio_buffer_add_demux(buffer, &p, in_loc, out_loc, length);
+		if (ret)
+			goto error_clear_mux_table;
 		out_loc += length;
 		in_loc += length;
 	}
@@ -936,3 +1352,45 @@
 	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);