staging:iio: Support functions for scan mask matching

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

diff --git a/drivers/staging/iio/iio.h b/drivers/staging/iio/iio.h
index 71dbfe1..a12072a 100644 (file)
--- a/drivers/staging/iio/iio.h
+++ b/drivers/staging/iio/iio.h
@@ -96,6 +96,7 @@ void iio_remove_event_from_list(struct iio_event_handler_list *el,
  *                     control method is used
  * @scan_count:        [INTERN] the number of elements in the current scan mode
  * @scan_mask:         [INTERN] bitmask used in masking scan mode elements
+ * @available_scan_masks: [DRIVER] optional array of allowed bitmasks
  * @scan_timestamp:    [INTERN] does the scan mode include a timestamp
  * @trig:              [INTERN] current device trigger (ring buffer modes)
  * @pollfunc:          [DRIVER] function run on trigger being recieved
@@ -122,7 +123,8 @@ struct iio_dev {
        struct attribute_group          *scan_el_attrs;
        int                             scan_count;
 
-       u16                             scan_mask;
+       u32                             scan_mask;
+       u32                             *available_scan_masks;
        bool                            scan_timestamp;
        struct iio_trigger              *trig;
        struct iio_poll_func            *pollfunc;
@@ -132,22 +134,57 @@ struct iio_dev {
  * These are mainly provided to allow for a change of implementation if a device
  * has a large number of scan elements
  */
-#define IIO_MAX_SCAN_LENGTH 15
+#define IIO_MAX_SCAN_LENGTH 31
+
+/* note 0 used as error indicator as it doesn't make sense. */
+static inline u32 iio_scan_mask_match(u32 *av_masks, u32 mask)
+{
+       while (*av_masks) {
+               if (!(~*av_masks & mask))
+                       return *av_masks;
+               av_masks++;
+       }
+       return 0;
+}
 
 static inline int iio_scan_mask_query(struct iio_dev *dev_info, int bit)
 {
+       u32 mask;
+
        if (bit > IIO_MAX_SCAN_LENGTH)
                return -EINVAL;
+
+       if (!dev_info->scan_mask)
+               return 0;
+
+       if (dev_info->available_scan_masks)
+               mask = iio_scan_mask_match(dev_info->available_scan_masks,
+                                       dev_info->scan_mask);
        else
-               return !!(dev_info->scan_mask & (1 << bit));
+               mask = dev_info->scan_mask;
+
+       if (!mask)
+               return -EINVAL;
+
+       return !!(mask & (1 << bit));
 };
 
 static inline int iio_scan_mask_set(struct iio_dev *dev_info, int bit)
 {
+       u32 mask;
+       u32 trialmask = dev_info->scan_mask | (1 << bit);
+
        if (bit > IIO_MAX_SCAN_LENGTH)
                return -EINVAL;
-       dev_info->scan_mask |= (1 << bit);
+       if (dev_info->available_scan_masks) {
+               mask = iio_scan_mask_match(dev_info->available_scan_masks,
+                                       trialmask);
+               if (!mask)
+                       return -EINVAL;
+       }
+       dev_info->scan_mask = trialmask;
        dev_info->scan_count++;
+
        return 0;
 };