1 files changed, 44 insertions, 8 deletions

diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
index ac185b8694bd..4add9bb40eeb 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,