ALSA: hdac: Add snd_hdac_get_hdac_stream()

Add a helper to find the stream using stream tag and direction.
This is useful for drivers to query stream based on stream tag
and direction, fox example while downloading FW thru DSP loader
code

Signed-off-by: Jeeja KP <jeeja.kp@intel.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/hdaudio.h

@@ -438,6 +438,8 @@ void snd_hdac_stream_init(struct hdac_bus *bus, struct hdac_stream *azx_dev,
 struct hdac_stream *snd_hdac_stream_assign(struct hdac_bus *bus,
 					   struct snd_pcm_substream *substream);
 void snd_hdac_stream_release(struct hdac_stream *azx_dev);
+struct hdac_stream *snd_hdac_get_stream(struct hdac_bus *bus,
+					int dir, int stream_tag);
 
 int snd_hdac_stream_setup(struct hdac_stream *azx_dev);
 void snd_hdac_stream_cleanup(struct hdac_stream *azx_dev);

sound/hda/hdac_stream.c

@@ -286,6 +286,28 @@ void snd_hdac_stream_release(struct hdac_stream *azx_dev)
 }
 EXPORT_SYMBOL_GPL(snd_hdac_stream_release);
 
+/**
+ * snd_hdac_get_stream - return hdac_stream based on stream_tag and
+ * direction
+ *
+ * @bus: HD-audio core bus
+ * @dir: direction for the stream to be found
+ * @stream_tag: stream tag for stream to be found
+ */
+struct hdac_stream *snd_hdac_get_stream(struct hdac_bus *bus,
+					int dir, int stream_tag)
+{
+	struct hdac_stream *s;
+
+	list_for_each_entry(s, &bus->stream_list, list) {
+		if (s->direction == dir && s->stream_tag == stream_tag)
+			return s;
+	}
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(snd_hdac_get_stream);
+
 /*
  * set up a BDL entry
  */