ALSA: rawmidi: Add const to snd_rawmidi_ops

Make snd_rawmidi_substream.ops to be a const pointer to be safer and
allow more optimization.  The patches to constify each rawmidi ops
will follow.

Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/rawmidi.h

@@ -103,7 +103,7 @@ struct snd_rawmidi_substream {
 	struct snd_rawmidi_runtime *runtime;
 	struct pid *pid;
 	/* hardware layer */
-	struct snd_rawmidi_ops *ops;
+	const struct snd_rawmidi_ops *ops;
 };
 
 struct snd_rawmidi_file {
@@ -155,7 +155,7 @@ int snd_rawmidi_new(struct snd_card *card, char *id, int device,
 		    int output_count, int input_count,
 		    struct snd_rawmidi **rmidi);
 void snd_rawmidi_set_ops(struct snd_rawmidi *rmidi, int stream,
-			 struct snd_rawmidi_ops *ops);
+			 const struct snd_rawmidi_ops *ops);
 
 /* callbacks */
 

sound/core/rawmidi.c

@@ -1749,7 +1749,7 @@ static int snd_rawmidi_dev_disconnect(struct snd_device *device)
  * Sets the rawmidi operators for the given stream direction.
  */
 void snd_rawmidi_set_ops(struct snd_rawmidi *rmidi, int stream,
-			 struct snd_rawmidi_ops *ops)
+			 const struct snd_rawmidi_ops *ops)
 {
 	struct snd_rawmidi_substream *substream;