[ALSA] rawmidi: add get_port_info callback for sequencer information flags

Add a get_port_info callback to the snd_rawmidi_global_ops structure to
allow the USB MIDI driver to supply information flags for the sequencer
ports created by seq_midi.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

include/sound/rawmidi.h

@@ -46,6 +46,7 @@
 
 struct snd_rawmidi;
 struct snd_rawmidi_substream;
+struct snd_seq_port_info;
 
 struct snd_rawmidi_ops {
 	int (*open) (struct snd_rawmidi_substream * substream);
@@ -57,6 +58,8 @@ struct snd_rawmidi_ops {
 struct snd_rawmidi_global_ops {
 	int (*dev_register) (struct snd_rawmidi * rmidi);
 	int (*dev_unregister) (struct snd_rawmidi * rmidi);
+	void (*get_port_info)(struct snd_rawmidi *rmidi, int number,
+			      struct snd_seq_port_info *info);
 };
 
 struct snd_rawmidi_runtime {

sound/core/seq/seq_midi.c

@@ -278,6 +278,7 @@ snd_seq_midisynth_register_port(struct snd_seq_device *dev)
 	struct seq_midisynth *msynth, *ms;
 	struct snd_seq_port_info *port;
 	struct snd_rawmidi_info *info;
+	struct snd_rawmidi *rmidi = dev->private_data;
 	int newclient = 0;
 	unsigned int p, ports;
 	struct snd_seq_port_callback pcallbacks;
@@ -389,6 +390,8 @@ snd_seq_midisynth_register_port(struct snd_seq_device *dev)
 		pcallbacks.unuse = midisynth_unuse;
 		pcallbacks.event_input = event_process_midi;
 		port->kernel = &pcallbacks;
+		if (rmidi->ops && rmidi->ops->get_port_info)
+			rmidi->ops->get_port_info(rmidi, p, port);
 		if (snd_seq_kernel_client_ctl(client->seq_client, SNDRV_SEQ_IOCTL_CREATE_PORT, port)<0)
 			goto __nomem;
 		ms->seq_client = client->seq_client;