1 files changed, 44 insertions, 8 deletions

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index ac185b8694b..4add9bb40ee 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -285,11 +285,14 @@ int iio_buffer_register(struct iio_dev *indio_dev,
 	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
-					= indio_dev->channels[i].scan_index + 1;
+					= channels[i].scan_index + 1;
 
 			ret = iio_buffer_add_channel_sysfs(indio_dev,
 							 &channels[i]);
@@ -553,6 +556,10 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
 					    buffer->scan_mask);
 	else
 		indio_dev->active_scan_mask = buffer->scan_mask;
+
+	if (indio_dev->active_scan_mask == NULL)
+		return -EINVAL;
+
 	iio_update_demux(indio_dev);
 
 	if (indio_dev->info->update_scan_mode)
@@ -564,6 +571,31 @@ int iio_sw_buffer_preenable(struct iio_dev *indio_dev)
 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)
+{
+	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
  * @buffer: the buffer whose scan mask we are interested in
  * @bit: the bit to be set.
@@ -582,27 +614,31 @@ int iio_scan_mask_set(struct iio_dev *indio_dev,
 		return -ENOMEM;
 	if (!indio_dev->masklength) {
 		WARN_ON("trying to set scanmask prior to registering buffer\n");
-		kfree(trialmask);
-		return -EINVAL;
+		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) {
-			kfree(trialmask);
-			return -EINVAL;
-		}
+		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,