sound: make OSS sound core optional

sound/sound_core.c implements soundcore.ko and contains two parts -
sound_class which is shared by both ALSA and OSS and device
redirection support for OSS. It's always compiled when any sound
support is enabled although it's necessary only when OSS (the actual
one or emulation) is enabled. This is slightly wasteful and as device
redirection always registers character device region for major 14, it
prevents alternative implementation.

This patch introduces a new config SOUND_OSS_CORE which is selected
iff OSS support is actually necessary and build the OSS core part
conditionally.

If OSS is disabled, soundcore merely contains sound_class but leaving
it that way seems to be the simplest approach as otherwise sound_class
should be in ALSA core file if OSS is disabled but should be in
soundcore if OSS is enabled. Also, there's also the user confusion
factor.

Signed-off-by: Tejun Heo <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>
Signed-off-by: Jaroslav Kysela <[e-mail]>

arch/um/Kconfig.char

···
 	tristate
 	default UML_SOUND
 
+config SOUND_OSS_CORE
+	bool
+	default UML_SOUND
+
 config HOSTAUDIO
 	tristate
 	default UML_SOUND

sound/Kconfig

···
 
 if SOUND
 
+config SOUND_OSS_CORE
+	bool
+	default n
+
 source "sound/oss/dmasound/Kconfig"
 
 if !M68K
···
 
 menuconfig SOUND_PRIME
 	tristate "Open Sound System (DEPRECATED)"
+	select SOUND_OSS_CORE
 	help
 	  Say 'Y' or 'M' to enable Open Sound System drivers.
 

sound/core/Kconfig

···
 	  will be called snd-seq-dummy.
 
 config SND_OSSEMUL
+	select SOUND_OSS_CORE
 	bool
 
 config SND_MIXER_OSS

sound/oss/dmasound/Kconfig

···
 
 config DMASOUND
 	tristate
+	select SOUND_OSS_CORE

sound/sound_core.c

···
 /*
- *	Sound core handling. Breaks out sound functions to submodules
+ *	Sound core.  This file is composed of two parts.  sound_class
+ *	which is common to both OSS and ALSA and OSS sound core which
+ *	is used OSS or emulation of it.
+ */
+
+/*
+ * First, the common part.
+ */
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+
+#ifdef CONFIG_SOUND_OSS_CORE
+static int __init init_oss_soundcore(void);
+static void __exit cleanup_oss_soundcore(void);
+#else
+static inline int init_oss_soundcore(void)	{ return 0; }
+static inline void cleanup_oss_soundcore(void)	{ }
+#endif
+
+struct class *sound_class;
+EXPORT_SYMBOL(sound_class);
+
+MODULE_DESCRIPTION("Core sound module");
+MODULE_AUTHOR("Alan Cox");
+MODULE_LICENSE("GPL");
+
+static int __init init_soundcore(void)
+{
+	int rc;
+
+	rc = init_oss_soundcore();
+	if (rc)
+		return rc;
+
+	sound_class = class_create(THIS_MODULE, "sound");
+	if (IS_ERR(sound_class)) {
+		cleanup_oss_soundcore();
+		return PTR_ERR(sound_class);
+	}
+
+	return 0;
+}
+
+static void __exit cleanup_soundcore(void)
+{
+	cleanup_oss_soundcore();
+	class_destroy(sound_class);
+}
+
+module_init(init_soundcore);
+module_exit(cleanup_soundcore);
+
+
+#ifdef CONFIG_SOUND_OSS_CORE
+/*
+ *	OSS sound core handling. Breaks out sound functions to submodules
  *	
  *	Author:		Alan Cox <[e-mail]>
  *
···
  *	locking at some point in 2.3.x.
  */
 
-#include <linux/module.h>
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 #include <linux/types.h>
 #include <linux/kernel.h>
-#include <linux/fs.h>
 #include <linux/sound.h>
 #include <linux/major.h>
 #include <linux/kmod.h>
-#include <linux/device.h>
 
 #define SOUND_STEP 16
-
 
 struct sound_unit
 {
···
 #ifdef CONFIG_SOUND_MSNDPIN
 extern int msnd_pinnacle_init(void);
 #endif
-
-struct class *sound_class;
-EXPORT_SYMBOL(sound_class);
 
 /*
  *	Low level list operator. Scan the ordered list, find a hole and
···
 	return -ENODEV;
 }
 
-MODULE_DESCRIPTION("Core sound module");
-MODULE_AUTHOR("Alan Cox");
-MODULE_LICENSE("GPL");
 MODULE_ALIAS_CHARDEV_MAJOR(SOUND_MAJOR);
 
-static void __exit cleanup_soundcore(void)
+static void __exit cleanup_oss_soundcore(void)
 {
 	/* We have nothing to really do here - we know the lists must be
 	   empty */
 	unregister_chrdev(SOUND_MAJOR, "sound");
-	class_destroy(sound_class);
 }
 
-static int __init init_soundcore(void)
+static int __init init_oss_soundcore(void)
 {
 	if (register_chrdev(SOUND_MAJOR, "sound", &soundcore_fops)==-1) {
 		printk(KERN_ERR "soundcore: sound device already in use.\n");
 		return -EBUSY;
 	}
-	sound_class = class_create(THIS_MODULE, "sound");
-	if (IS_ERR(sound_class))
-		return PTR_ERR(sound_class);
 
 	return 0;
 }
 
-module_init(init_soundcore);
-module_exit(cleanup_soundcore);
+#endif /* CONFIG_SOUND_OSS_CORE */