ALSA: core: add support for compressed devices

Use the minor numbers 2 and 3 for audio compressed offload devices.
Also add support for these devices in core

Signed-off-by: Omair Mohammed Abdullah <[e-mail]>
Signed-off-by: Pierre-Louis Bossart <[e-mail]>
Signed-off-by: Vinod Koul <[e-mail]>
Reviewed-by: Mark Brown <[e-mail]>
Signed-off-by: Takashi Iwai <[e-mail]>

include/sound/core.h

···
 #define	SNDRV_DEV_BUS		((__force snd_device_type_t) 0x1007)
 #define	SNDRV_DEV_CODEC		((__force snd_device_type_t) 0x1008)
 #define	SNDRV_DEV_JACK          ((__force snd_device_type_t) 0x1009)
+#define	SNDRV_DEV_COMPRESS	((__force snd_device_type_t) 0x100A)
 #define	SNDRV_DEV_LOWLEVEL	((__force snd_device_type_t) 0x2000)
 
 typedef int __bitwise snd_device_state_t;

include/sound/minors.h

···
 #define SNDRV_MINOR_TIMER		33	/* SNDRV_MINOR_GLOBAL + 1 * 32 */
 
 #ifndef CONFIG_SND_DYNAMIC_MINORS
-						/* 2 - 3 (reserved) */
+#define SNDRV_MINOR_COMPRESS		2	/* 2 - 3 */
 #define SNDRV_MINOR_HWDEP		4	/* 4 - 7 */
 #define SNDRV_MINOR_RAWMIDI		8	/* 8 - 15 */
 #define SNDRV_MINOR_PCM_PLAYBACK	16	/* 16 - 23 */
···
 #define SNDRV_DEVICE_TYPE_PCM_CAPTURE	SNDRV_MINOR_PCM_CAPTURE
 #define SNDRV_DEVICE_TYPE_SEQUENCER	SNDRV_MINOR_SEQUENCER
 #define SNDRV_DEVICE_TYPE_TIMER		SNDRV_MINOR_TIMER
+#define SNDRV_DEVICE_TYPE_COMPRESS	SNDRV_MINOR_COMPRESS
 
 #else /* CONFIG_SND_DYNAMIC_MINORS */
 
···
 	SNDRV_DEVICE_TYPE_RAWMIDI,
 	SNDRV_DEVICE_TYPE_PCM_PLAYBACK,
 	SNDRV_DEVICE_TYPE_PCM_CAPTURE,
+	SNDRV_DEVICE_TYPE_COMPRESS,
 };
 
 #endif /* CONFIG_SND_DYNAMIC_MINORS */

sound/core/sound.c

···
 	case SNDRV_DEVICE_TYPE_RAWMIDI:
 	case SNDRV_DEVICE_TYPE_PCM_PLAYBACK:
 	case SNDRV_DEVICE_TYPE_PCM_CAPTURE:
+	case SNDRV_DEVICE_TYPE_COMPRESS:
 		if (snd_BUG_ON(!card))
 			return -EINVAL;
 		minor = SNDRV_MINOR(card->number, type + dev);