[PATCH 4/5] staging:iio: add demux optionally to path from device to buffer

[Jonathan Cameron <jic23@cam.ac.uk>]

This gives you only what you ask for which is handy
for some devices with weird scan combinations.

Routes all data flow through a core utility function.
That and this demuxing support will be needed to do
demuxing to multiple destinations in kernel.

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
---
 drivers/staging/iio/buffer_generic.h      |   15 ++++
 drivers/staging/iio/industrialio-buffer.c |  120 ++++++++++++++++++++++++++++-
 2 files changed, 131 insertions(+), 4 deletions(-)

diff --git a/drivers/staging/iio/buffer_generic.h b/drivers/staging/iio/buffer_generic.h
index 9e8f010..1b0e781 100644
--- a/drivers/staging/iio/buffer_generic.h
+++ b/drivers/staging/iio/buffer_generic.h
@@ -96,6 +96,8 @@ struct iio_buffer_setup_ops {
  * @access:		[DRIVER] buffer access functions associated with the
  *			implementation.
  * @flags:		[INTERN] file ops related flags including busy flag.
+ * @demux_list:		[INTERN] list of operations required to demux the scan.
+ * @demux_bounce:	[INTERN] buffer for doing gather from incoming scan.
  **/
 struct iio_buffer {
 	struct iio_dev				*indio_dev;
@@ -115,6 +117,8 @@ struct iio_buffer {
 	bool					stufftoread;
 	unsigned long				flags;
 	const struct attribute_group *attrs;
+	struct list_head			demux_list;
+	unsigned char				*demux_bounce;
 };
 
 /**
@@ -153,6 +157,17 @@ int iio_scan_mask_set(struct iio_buffer *buffer, int bit);
 	container_of(d, struct iio_buffer, dev)
 
 /**
+ * iio_push_to_buffer() - push to a registered buffer.
+ * @buffer:		IIO buffer structure for device
+ * @scan:		Full scan.
+ * @timestamp:
+ */
+int iio_push_to_buffer(struct iio_buffer *buffer, unsigned char *data,
+		       s64 timestamp);
+
+int iio_update_demux(struct iio_dev *indio_dev);
+
+/**
  * iio_buffer_register() - register the buffer with IIO core
  * @indio_dev: device with the buffer to be registered
  **/
diff --git a/drivers/staging/iio/industrialio-buffer.c b/drivers/staging/iio/industrialio-buffer.c
index 6dd5d7d..bac672d 100644
--- a/drivers/staging/iio/industrialio-buffer.c
+++ b/drivers/staging/iio/industrialio-buffer.c
@@ -125,10 +125,9 @@ static ssize_t iio_scan_el_show(struct device *dev,
 	int ret;
 	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 
-	ret = iio_scan_mask_query(indio_dev->buffer,
-				  to_iio_dev_attr(attr)->address);
-	if (ret < 0)
-		return ret;
+	ret = test_bit(to_iio_dev_attr(attr)->address,
+		       indio_dev->buffer->scan_mask);
+
 	return sprintf(buf, "%d\n", ret);
 }
 
@@ -295,6 +294,7 @@ int iio_buffer_register(struct iio_dev *indio_dev,
 			attrcount_orig++;
 	}
 	attrcount = attrcount_orig;
+	INIT_LIST_HEAD(&buffer->demux_list);
 	INIT_LIST_HEAD(&buffer->scan_el_dev_attr_list);
 	if (channels) {
 		/* new magic */
@@ -633,3 +633,115 @@ int iio_scan_mask_query(struct iio_buffer *buffer, int bit)
 	return test_bit(bit, 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);
+
+int iio_update_demux(struct iio_dev *indio_dev)
+{
+	const struct iio_chan_spec *ch;
+	struct iio_buffer *buffer = indio_dev->buffer;
+	long *in_mask;
+	int ret, in_ind = -1, out_ind, length;
+	unsigned in_loc = 0, out_loc = 0;
+	struct iio_demux_table *p, *q;
+
+	/* Clear out any old demux */
+	list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
+		list_del(&p->l);
+		kfree(p);
+	}
+	kfree(buffer->demux_bounce);
+
+	/* First work out which scan mode we will actually have */
+	in_mask = iio_scan_mask_match(indio_dev->available_scan_masks,
+				   indio_dev->masklength,
+				   buffer->scan_mask);
+
+	out_ind = find_first_bit(buffer->scan_mask, indio_dev->masklength);
+	/* Now we have the two masks, work from least sig and build up sizes */
+	while (out_ind != indio_dev->masklength) {
+		in_ind = find_next_bit(in_mask,
+				       indio_dev->masklength,
+				       in_ind + 1);
+		while (in_ind != out_ind) {
+			in_ind = find_next_bit(in_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;
+		out_ind = find_next_bit(buffer->scan_mask,
+					indio_dev->masklength,
+					out_ind + 1);
+	}
+	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:
+	list_for_each_entry_safe(p, q, &buffer->demux_list, l) {
+		list_del(&p->l);
+		kfree(p);
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iio_update_demux);
-- 
1.7.7