ALSA: seq: Allow the tristate build of OSS emulation

Currently OSS sequencer emulation is tied with ALSA sequencer core,
both are built in the same level; i.e. when CONFIG_SND_SEQUENCER=y,
the OSS sequencer emulation is also always built-in, even though the
functionality can be built as an individual module.

This patch changes the rule and allows users to build snd-seq-oss
module while others are built-in.  Essentially, it's just a few simple
changes in Kconfig and Makefile.  Some driver codes like opl3 need to
convert from the simple ifdef to IS_ENABLED().  But that's all.

You might wonder how about the dependency: right, it can be messy, but
it still works.  Since we rewrote the sequencer binding with the
standard bus, the driver can be bound at any time on demand.  So, the
synthesizer driver module can be loaded individually from the OSS
emulation core before/after it.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

2 files changed, 6 insertions, 3 deletions

diff --git a/sound/drivers/opl3/opl3_seq.c b/sound/drivers/opl3/opl3_seq.c
index fdae5d7f421f..d3e91be8b23a 100644
--- a/sound/drivers/opl3/opl3_seq.c
+++ b/sound/drivers/opl3/opl3_seq.c
@@ -252,7 +252,7 @@ static int snd_opl3_seq_probe(struct device *_dev)
         spin_lock_init(&opl3->sys_timer_lock);
         opl3->sys_timer_status = 0;
 
-#ifdef CONFIG_SND_SEQUENCER_OSS
+#if IS_ENABLED(CONFIG_SND_SEQUENCER_OSS)
         snd_opl3_init_seq_oss(opl3, name);
 #endif
         return 0;
@@ -267,7 +267,7 @@ static int snd_opl3_seq_remove(struct device *_dev)
         if (opl3 == NULL)
                 return -EINVAL;
 
-#ifdef CONFIG_SND_SEQUENCER_OSS
+#if IS_ENABLED(CONFIG_SND_SEQUENCER_OSS)
         snd_opl3_free_seq_oss(opl3);
 #endif
         if (opl3->seq_client >= 0) {
diff --git a/sound/drivers/opl3/opl3_voice.h b/sound/drivers/opl3/opl3_voice.h
index a371c075ac87..eaef435e0528 100644
--- a/sound/drivers/opl3/opl3_voice.h
+++ b/sound/drivers/opl3/opl3_voice.h
@@ -44,9 +44,12 @@ void snd_opl3_load_drums(struct snd_opl3 *opl3);
 void snd_opl3_drum_switch(struct snd_opl3 *opl3, int note, int on_off, int vel, struct snd_midi_channel *chan);
 
 /* Prototypes for opl3_oss.c */
-#ifdef CONFIG_SND_SEQUENCER_OSS
+#if IS_ENABLED(CONFIG_SND_SEQUENCER_OSS)
 void snd_opl3_init_seq_oss(struct snd_opl3 *opl3, char *name);
 void snd_opl3_free_seq_oss(struct snd_opl3 *opl3);
+#else
+#define snd_opl3_init_seq_oss(opl3, name) /* NOP */
+#define snd_opl3_free_seq_oss(opl3) /* NOP */
 #endif
 
 #endif