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 <[e-mail]>

sound/core/Kconfig

···
 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

sound/core/Makefile

···
 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
 
···
 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/

sound/core/rawmidi.c

···
 	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;
···
 		}
 	}
 	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;

sound/core/seq/Kconfig

···
 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
···
 	tristate
 
 endif # SND_SEQUENCER
-

sound/core/seq/Makefile

···
 # Copyright (c) 1999 by Jaroslav Kysela <[e-mail]>
 #
 
-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
···
 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

sound/drivers/Kconfig

···
 	tristate
 	select SND_TIMER
 	select SND_HWDEP
+	select SND_SEQ_DEVICE if SND_SEQUENCER != n
 
 config SND_OPL4_LIB
 	tristate
 	select SND_TIMER
 	select SND_HWDEP
+	select SND_SEQ_DEVICE if SND_SEQUENCER != n
 
 # select SEQ stuff to min(SND_SEQUENCER,SND_XXX)
 config SND_OPL3_LIB_SEQ

sound/drivers/opl3/opl3_lib.c

···
 
 	opl3->hwdep = hw;
 	opl3->seq_dev_num = seq_device;
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 	if (snd_seq_device_new(card, seq_device, SNDRV_SEQ_DEV_ID_OPL3,
 			       sizeof(struct snd_opl3 *), &opl3->seq_dev) >= 0) {
 		strcpy(opl3->seq_dev->name, hw->name);

sound/drivers/opl4/opl4_lib.c

···
 	return 0;
 }
 
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 static void snd_opl4_seq_dev_free(struct snd_seq_device *seq_dev)
 {
 	struct snd_opl4 *opl4 = seq_dev->private_data;
···
 	snd_opl4_create_mixer(opl4);
 	snd_opl4_create_proc(opl4);
 
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 	opl4->seq_client = -1;
 	if (opl4->hardware < OPL3_HW_OPL4_ML)
 		snd_opl4_create_seq_dev(opl4, seq_device);

sound/drivers/opl4/opl4_local.h

···
 #endif
 	struct mutex access_mutex;
 
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 	int used;
 
 	int seq_dev_num;

sound/isa/Kconfig

···
 	select SND_OPL3_LIB
 	select SND_MPU401_UART
 	select SND_SB16_DSP
+	select SND_SEQ_DEVICE if SND_SEQUENCER != n
 	help
 	  Say Y here to include support for Sound Blaster AWE soundcards
 	  (including the Plug and Play version).

sound/isa/sb/emu8000.c

···
 		snd_emu8000_free(hw);
 		return err;
 	}
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 	if (snd_seq_device_new(card, index, SNDRV_SEQ_DEV_ID_EMU8000,
 			       sizeof(struct snd_emu8000*), &awe) >= 0) {
 		strcpy(awe->name, "EMU-8000");

sound/isa/sb/sb16.c

···
 #define SNDRV_DEBUG_IRQ
 #endif
 
-#if defined(SNDRV_SBAWE) && IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if defined(SNDRV_SBAWE) && IS_ENABLED(CONFIG_SND_SEQUENCER)
 #define SNDRV_SBAWE_EMU8000
 #endif
 

sound/pci/Kconfig

···
 	select SND_RAWMIDI
 	select SND_AC97_CODEC
 	select SND_TIMER
+	select SND_SEQ_DEVICE if SND_SEQUENCER != n
 	depends on ZONE_DMA
 	help
 	  Say Y to include support for Sound Blaster PCI 512, Live!,

sound/pci/emu10k1/emu10k1.c

···
 MODULE_SUPPORTED_DEVICE("{{Creative Labs,SB Live!/PCI512/E-mu APS},"
 	       "{Creative Labs,SB Audigy}}");
 
-#if IS_REACHABLE(CONFIG_SND_SEQUENCER)
+#if IS_ENABLED(CONFIG_SND_SEQUENCER)
 #define ENABLE_SYNTH
 #include <sound/emu10k1_synth.h>
 #endif