ALSA: xen-front: Read sound driver configuration from Xen store

Read configuration values from Xen store according
to xen/interface/io/sndif.h protocol:
  - introduce configuration structures for different
    components, e.g. sound card, device, stream
  - read PCM HW parameters, e.g rate, format etc.
  - detect stream type (capture/playback)
  - read device and card parameters
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/xen/Makefile

 # SPDX-License-Identifier: GPL-2.0 OR MIT
 
-snd_xen_front-objs := xen_snd_front.o
+snd_xen_front-objs := xen_snd_front.o \
+		      xen_snd_front_cfg.o
 
 obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o

sound/xen/xen_snd_front.c

@@ -25,6 +25,13 @@ static void xen_snd_drv_fini(struct xen_snd_front_info *front_info)
 
 static int sndback_initwait(struct xen_snd_front_info *front_info)
 {
+	int num_streams;
+	int ret;
+
+	ret = xen_snd_front_cfg_card(front_info, &num_streams);
+	if (ret < 0)
+		return ret;
+
 	return 0;
 }
 

sound/xen/xen_snd_front.h

@@ -11,8 +11,12 @@
 #ifndef __XEN_SND_FRONT_H
 #define __XEN_SND_FRONT_H
 
+#include "xen_snd_front_cfg.h"
+
 struct xen_snd_front_info {
 	struct xenbus_device *xb_dev;
+
+	struct xen_front_cfg_card cfg;
 };
 
 #endif /* __XEN_SND_FRONT_H */

sound/xen/xen_snd_front_cfg.h

+/* SPDX-License-Identifier: GPL-2.0 OR MIT */
+
+/*
+ * Xen para-virtual sound device
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ */
+
+#ifndef __XEN_SND_FRONT_CFG_H
+#define __XEN_SND_FRONT_CFG_H
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+
+struct xen_snd_front_info;
+
+struct xen_front_cfg_stream {
+	int index;
+	char *xenstore_path;
+	struct snd_pcm_hardware pcm_hw;
+};
+
+struct xen_front_cfg_pcm_instance {
+	char name[80];
+	int device_id;
+	struct snd_pcm_hardware pcm_hw;
+	int  num_streams_pb;
+	struct xen_front_cfg_stream *streams_pb;
+	int  num_streams_cap;
+	struct xen_front_cfg_stream *streams_cap;
+};
+
+struct xen_front_cfg_card {
+	char name_short[32];
+	char name_long[80];
+	struct snd_pcm_hardware pcm_hw;
+	int num_pcm_instances;
+	struct xen_front_cfg_pcm_instance *pcm_instances;
+};
+
+int xen_snd_front_cfg_card(struct xen_snd_front_info *front_info,
+			   int *stream_cnt);
+
+#endif /* __XEN_SND_FRONT_CFG_H */