ALSA: seq: Allow the modular sequencer registration

Many drivers bind the sequencer stuff in off-load by another driver
module, so that it's loaded only on demand.  In the current code, this
mechanism doesn't work when the driver is built-in while the sequencer
is module.  We check with IS_REACHABLE() and enable only when the
sequencer is in the same level of build.

However, this is basically a overshoot.  The binder code
(snd-seq-device) is an individual module from the sequencer core
(snd-seq), and we just have to make the former a built-in while
keeping the latter a module for allowing the scenario like the above.

This patch achieves that by rewriting Kconfig slightly.  Now, a driver
that provides the manual sequencer device binding should select
CONFIG_SND_SEQ_DEVICE in a way as
	select SND_SEQ_DEVICE if SND_SEQUENCER != n

Note that the "!=n" is needed here to avoid the influence of the
sequencer core is module while the driver is built-in.

Also, since rawmidi.o may be linked with snd_seq_device.o when
built-in, we have to shuffle the code to make the linker happy.
(the kernel linker isn't smart enough yet to handle such a case.)
That is, snd_seq_device.c is moved to sound/core from sound/core/seq,
as well as Makefile.

Last but not least, the patch replaces the code using IS_REACHABLE()
with IS_ENABLED(), since now the condition meets always when enabled.

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

6 files changed, 10 insertions, 5 deletions

diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index 90990eb1d250..6e937a8146a1 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -18,8 +18,12 @@ config SND_DMAENGINE_PCM
 config SND_HWDEP
 	tristate
 
+config SND_SEQ_DEVICE
+	tristate
+
 config SND_RAWMIDI
 	tristate
+	select SND_SEQ_DEVICE if SND_SEQUENCER != n
 
 config SND_COMPRESS_OFFLOAD
 	tristate
diff --git a/sound/core/Makefile b/sound/core/Makefile
index a8514b313a89..e2066e2ef9f8 100644
--- a/sound/core/Makefile
+++ b/sound/core/Makefile
@@ -31,6 +31,7 @@ snd-timer-objs    := timer.o
 snd-hrtimer-objs  := hrtimer.o
 snd-rtctimer-objs := rtctimer.o
 snd-hwdep-objs    := hwdep.o
+snd-seq-device-objs := seq_device.o
 
 snd-compress-objs := compress_offload.o
 
@@ -40,6 +41,7 @@ obj-$(CONFIG_SND_TIMER)		+= snd-timer.o
 obj-$(CONFIG_SND_HRTIMER)	+= snd-hrtimer.o
 obj-$(CONFIG_SND_PCM)		+= snd-pcm.o
 obj-$(CONFIG_SND_DMAENGINE_PCM)	+= snd-pcm-dmaengine.o
+obj-$(CONFIG_SND_SEQ_DEVICE)	+= snd-seq-device.o
 obj-$(CONFIG_SND_RAWMIDI)	+= snd-rawmidi.o
 
 obj-$(CONFIG_SND_OSSEMUL)	+= oss/
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index ab890336175f..153d78bc79c0 100644
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -1610,7 +1610,7 @@ static int snd_rawmidi_dev_free(struct snd_device *device)
 	return snd_rawmidi_free(rmidi);
 }
 
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 static void snd_rawmidi_dev_seq_free(struct snd_seq_device *device)
 {
 	struct snd_rawmidi *rmidi = device->private_data;
@@ -1691,7 +1691,7 @@ static int snd_rawmidi_dev_register(struct snd_device *device)
 		}
 	}
 	rmidi->proc_entry = entry;
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 	if (!rmidi->ops || !rmidi->ops->dev_register) { /* own registration mechanism */
 		if (snd_seq_device_new(rmidi->card, rmidi->device, SNDRV_SEQ_DEV_ID_MIDISYNTH, 0, &rmidi->seq_dev) >= 0) {
 			rmidi->seq_dev->private_data = rmidi;
diff --git a/sound/core/seq/Kconfig b/sound/core/seq/Kconfig
index 140e640e62a6..a536760a94c2 100644
--- a/sound/core/seq/Kconfig
+++ b/sound/core/seq/Kconfig
@@ -1,6 +1,7 @@
 config SND_SEQUENCER
 	tristate "Sequencer support"
 	select SND_TIMER
+	select SND_SEQ_DEVICE
 	help
 	  Say Y or M to enable MIDI sequencer and router support.  This
 	  feature allows routing and enqueueing of MIDI events.  Events
@@ -59,4 +60,3 @@ config SND_SEQ_VIRMIDI
 	tristate
 
 endif # SND_SEQUENCER
-
diff --git a/sound/core/seq/Makefile b/sound/core/seq/Makefile
index 81a8ea537209..68fd367ac39c 100644
--- a/sound/core/seq/Makefile
+++ b/sound/core/seq/Makefile
@@ -3,7 +3,6 @@
 # Copyright (c) 1999 by Jaroslav Kysela <perex@perex.cz>
 #
 
-snd-seq-device-objs := seq_device.o
 snd-seq-objs := seq.o seq_lock.o seq_clientmgr.o seq_memory.o seq_queue.o \
                 seq_fifo.o seq_prioq.o seq_timer.o \
                 seq_system.o seq_ports.o
@@ -14,7 +13,7 @@ snd-seq-midi-event-objs := seq_midi_event.o
 snd-seq-dummy-objs := seq_dummy.o
 snd-seq-virmidi-objs := seq_virmidi.o
 
-obj-$(CONFIG_SND_SEQUENCER) += snd-seq.o snd-seq-device.o
+obj-$(CONFIG_SND_SEQUENCER) += snd-seq.o
 obj-$(CONFIG_SND_SEQUENCER_OSS) += oss/
 
 obj-$(CONFIG_SND_SEQ_DUMMY) += snd-seq-dummy.o
diff --git a/sound/core/seq/seq_device.c b/sound/core/seq_device.c
index c4acf17e9f5e..c4acf17e9f5e 100644
--- a/sound/core/seq/seq_device.c
+++ b/sound/core/seq_device.c