[PATCH v8 33/36] media: subdev: add "opposite" stream helper funcs

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

Add two helper functions to make dealing with streams easier:

v4l2_state_find_opposite_end - given a routing table and a pad + stream,
return the pad + stream on the opposite side of the subdev.

v4l2_state_get_opposite_stream_format - return a pointer to the format
on the pad + stream on the opposite side from the given pad + stream.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/v4l2-core/v4l2-subdev.c | 42 +++++++++++++++++++++++++++
 include/media/v4l2-subdev.h           | 31 ++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index e8bfca595e11..68db3f23c256 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -1487,3 +1487,45 @@ v4l2_state_get_stream_format(struct v4l2_subdev_state *state, unsigned int pad,
 	return NULL;
 }
 EXPORT_SYMBOL_GPL(v4l2_state_get_stream_format);
+
+int v4l2_state_find_opposite_end(struct v4l2_subdev_krouting *routing, u32 pad,
+				 u32 stream, u32 *other_pad, u32 *other_stream)
+{
+	unsigned int i;
+
+	for (i = 0; i < routing->num_routes; ++i) {
+		struct v4l2_subdev_route *route = &routing->routes[i];
+
+		if (route->source_pad == pad &&
+		    route->source_stream == stream) {
+			*other_pad = route->sink_pad;
+			*other_stream = route->sink_stream;
+			return 0;
+		}
+
+		if (route->sink_pad == pad && route->sink_stream == stream) {
+			*other_pad = route->source_pad;
+			*other_stream = route->source_stream;
+			return 0;
+		}
+	}
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(v4l2_state_find_opposite_end);
+
+struct v4l2_mbus_framefmt *
+v4l2_state_get_opposite_stream_format(struct v4l2_subdev_state *state, u32 pad,
+				      u32 stream)
+{
+	u32 other_pad, other_stream;
+	int ret;
+
+	ret = v4l2_state_find_opposite_end(&state->routing, pad, stream,
+					   &other_pad, &other_stream);
+	if (ret)
+		return NULL;
+
+	return v4l2_state_get_stream_format(state, other_pad, other_stream);
+}
+EXPORT_SYMBOL_GPL(v4l2_state_get_opposite_stream_format);
diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h
index 5a2c7e2cb561..bc69123f71cb 100644
--- a/include/media/v4l2-subdev.h
+++ b/include/media/v4l2-subdev.h
@@ -1500,4 +1500,35 @@ struct v4l2_mbus_framefmt *
 v4l2_state_get_stream_format(struct v4l2_subdev_state *state, unsigned int pad,
 			     u32 stream);
 
+/**
+ * v4l2_state_find_opposite_end() - Find the opposite stream
+ * @routing: routing used to find the opposite side
+ * @pad: pad id
+ * @stream: stream id
+ * @other_pad: pointer used to return the opposite pad
+ * @other_stream: pointer used to return the opposite stream
+ *
+ * This function uses the routing table to find the pad + stream which is
+ * opposite the given pad + stream.
+ *
+ * Returns 0 on success, or -EINVAL if no matching route is found.
+ */
+int v4l2_state_find_opposite_end(struct v4l2_subdev_krouting *routing, u32 pad,
+				 u32 stream, u32 *other_pad, u32 *other_stream);
+
+/**
+ * v4l2_state_get_opposite_stream_format() - Get pointer to opposite stream format
+ * @state: subdevice state
+ * @pad: pad id
+ * @stream: stream id
+ *
+ * This returns a pointer to &struct v4l2_mbus_framefmt for the pad + stream
+ * that is opposite the given pad + stream in the subdev state.
+ *
+ * If the state does not contain the given pad + stream, NULL is returned.
+ */
+struct v4l2_mbus_framefmt *
+v4l2_state_get_opposite_stream_format(struct v4l2_subdev_state *state, u32 pad,
+				      u32 stream);
+
 #endif
-- 
2.25.1