ALSA: fireface: add model specific structure

RME Fireface series has several models and their specifications are
different. Currently, we find no way to retrieve the specifications
from actual devices and need to implement them in this driver.

This commit adds a structure to describe model specific data. This
structure has an identical name for each unit, and maximum number of
data channels in each mode. I'll describe about the mode in following
commits.

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

sound/firewire/fireface/ff.h

@@ -22,6 +22,18 @@
 
 #include "../lib.h"
 
+#define SND_FF_STREAM_MODES		3
+
+struct snd_ff_spec {
+	const char *const name;
+
+	const unsigned int pcm_capture_channels[SND_FF_STREAM_MODES];
+	const unsigned int pcm_playback_channels[SND_FF_STREAM_MODES];
+
+	unsigned int midi_in_ports;
+	unsigned int midi_out_ports;
+};
+
 struct snd_ff {
 	struct snd_card *card;
 	struct fw_unit *unit;
@@ -29,5 +41,7 @@ struct snd_ff {
 
 	bool registered;
 	struct delayed_work dwork;
+
+	const struct snd_ff_spec *spec;
 };
 #endif