staging:iio: Switch the channel masks to bitmaps so as to allow for more channels.

This is as light as possible on changes to current drivers.
Some drivers make assumptions that their masks fit in a single
long.  Given they were previously working this is clearly valid if
not tidy.

The max1363 is an example where there should be no such assumptions.

V2: Add the new ad5933

Signed-off-by: Jonathan Cameron <jic23@cam.ac.uk>
Acked-by: Michael Hennerich <Michael.Hennerich@analog.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 100 insertions, 3 deletions

diff --git a/drivers/staging/iio/industrialio-ring.c b/drivers/staging/iio/industrialio-ring.c
index 23967d4..6f14c0d 100644
--- a/drivers/staging/iio/industrialio-ring.c
+++ b/drivers/staging/iio/industrialio-ring.c
@@ -132,9 +132,7 @@ static ssize_t iio_scan_el_show(struct device *dev,
 
 static int iio_scan_mask_clear(struct iio_ring_buffer *ring, int bit)
 {
-	if (bit > IIO_MAX_SCAN_LENGTH)
-		return -EINVAL;
-	ring->scan_mask &= ~(1 << bit);
+	clear_bit(bit, ring->scan_mask);
 	ring->scan_count--;
 	return 0;
 }
@@ -323,11 +321,27 @@ int iio_ring_buffer_register(struct iio_dev *indio_dev,
 	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_ring_add_channel_sysfs(indio_dev,
 							 &channels[i]);
 			if (ret < 0)
 				goto error_cleanup_group;
 		}
+		if (indio_dev->masklength && ring->scan_mask == NULL) {
+			ring->scan_mask
+				= kzalloc(sizeof(*ring->scan_mask)*
+					  BITS_TO_LONGS(indio_dev->masklength),
+					  GFP_KERNEL);
+			if (ring->scan_mask == NULL) {
+				ret = -ENOMEM;
+				goto error_cleanup_group;
+			}
+		}
 	}
 
 	return 0;
@@ -343,6 +357,7 @@ EXPORT_SYMBOL(iio_ring_buffer_register);
 
 void iio_ring_buffer_unregister(struct iio_dev *indio_dev)
 {
+	kfree(indio_dev->ring->scan_mask);
 	if (indio_dev->ring->attrs)
 		sysfs_remove_group(&indio_dev->dev.kobj,
 				   indio_dev->ring->attrs);
@@ -539,3 +554,85 @@ int iio_sw_ring_preenable(struct iio_dev *indio_dev)
 	return 0;
 }
 EXPORT_SYMBOL(iio_sw_ring_preenable);
+
+
+/* note NULL used as error indicator as it doesn't make sense. */
+static unsigned long *iio_scan_mask_match(unsigned long *av_masks,
+					  unsigned int masklength,
+					  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;
+}
+
+/**
+ * iio_scan_mask_set() - set particular bit in the scan mask
+ * @ring: the ring buffer whose scan mask we are interested in
+ * @bit: the bit to be set.
+ **/
+int iio_scan_mask_set(struct iio_ring_buffer *ring, int bit)
+{
+	struct iio_dev *dev_info = ring->indio_dev;
+	unsigned long *mask;
+	unsigned long *trialmask;
+
+	trialmask = kmalloc(sizeof(*trialmask)*
+			    BITS_TO_LONGS(dev_info->masklength),
+			    GFP_KERNEL);
+
+	if (trialmask == NULL)
+		return -ENOMEM;
+	if (!dev_info->masklength) {
+		WARN_ON("trying to set scan mask prior to registering ring\n");
+		kfree(trialmask);
+		return -EINVAL;
+	}
+	bitmap_copy(trialmask, ring->scan_mask, dev_info->masklength);
+	set_bit(bit, trialmask);
+
+	if (dev_info->available_scan_masks) {
+		mask = iio_scan_mask_match(dev_info->available_scan_masks,
+					   dev_info->masklength,
+					   trialmask);
+		if (!mask) {
+			kfree(trialmask);
+			return -EINVAL;
+		}
+	}
+	bitmap_copy(ring->scan_mask, trialmask, dev_info->masklength);
+	ring->scan_count++;
+
+	kfree(trialmask);
+
+	return 0;
+};
+EXPORT_SYMBOL_GPL(iio_scan_mask_set);
+
+int iio_scan_mask_query(struct iio_ring_buffer *ring, int bit)
+{
+	struct iio_dev *dev_info = ring->indio_dev;
+	long *mask;
+
+	if (bit > dev_info->masklength)
+		return -EINVAL;
+
+	if (!ring->scan_mask)
+		return 0;
+	if (dev_info->available_scan_masks)
+		mask = iio_scan_mask_match(dev_info->available_scan_masks,
+					   dev_info->masklength,
+					   ring->scan_mask);
+	else
+		mask = ring->scan_mask;
+	if (!mask)
+		return 0;
+
+	return test_bit(bit, mask);
+};
+EXPORT_SYMBOL_GPL(iio_scan_mask_query);