iio: buffer-callback: allow getting underlying iio_dev

Add iio_channel_cb_get_iio_dev function to allow getting the
underlying iio_dev. This is useful for setting the trigger of the
consumer ADC device.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

include/linux/iio/consumer.h

@@ -164,6 +164,18 @@ void iio_channel_stop_all_cb(struct iio_cb_buffer *cb_buff);
 struct iio_channel
 *iio_channel_cb_get_channels(const struct iio_cb_buffer *cb_buffer);
 
+/**
+ * iio_channel_cb_get_iio_dev() - get access to the underlying device.
+ * @cb_buffer:		The callback buffer from whom we want the device
+ *			information.
+ *
+ * This function allows one to obtain information about the device.
+ * The primary aim is to allow drivers that are consuming a device to query
+ * things like current trigger.
+ */
+struct iio_dev
+*iio_channel_cb_get_iio_dev(const struct iio_cb_buffer *cb_buffer);
+
 /**
  * iio_read_channel_raw() - read from a given channel
  * @chan:		The channel being queried.