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[Xen-devel] [PATCH v3 1/2] xen-sndfront: add sound frontend driver



This is Para-virtual sound driver.

Frontend driver registers an virtual sound card
and sends an PCM streams to the backend driver.
Backend driver is an user-space application and
uses ALSA with dmix plugin to play audio.

Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@xxxxxxxxxxxxxxx>
Signed-off-by: Iurii Konovalenko <iurii.konovalenko@xxxxxxxxxxxxxxx>
---
 include/xen/interface/io/sndif.h |  208 ++++++
 sound/drivers/Kconfig            |   10 +
 sound/drivers/Makefile           |    2 +
 sound/drivers/xen-sndfront.c     | 1478 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 1698 insertions(+)
 create mode 100644 include/xen/interface/io/sndif.h
 create mode 100644 sound/drivers/xen-sndfront.c

diff --git a/include/xen/interface/io/sndif.h b/include/xen/interface/io/sndif.h
new file mode 100644
index 0000000..99e6f8e
--- /dev/null
+++ b/include/xen/interface/io/sndif.h
@@ -0,0 +1,208 @@
+/******************************************************************************
+ * sndif.h
+ *
+ * Unified sound-device I/O interface for Xen guest OSes.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Copyright (C) 2013-2015 GlobalLogic Inc.
+ */
+
+#ifndef __XEN_PUBLIC_IO_SNDIF_H__
+#define __XEN_PUBLIC_IO_SNDIF_H__
+
+#include <xen/interface/io/ring.h>
+#include <xen/interface/grant_table.h>
+
+/*
+ * Feature and Parameter Negotiation
+ * =================================
+ * The two halves of a Xen vsnd driver utilize nodes within the XenStore to
+ * communicate capabilities and to negotiate operating parameters.  This
+ * section enumerates these nodes which reside in the respective front and
+ * backend portions of the XenStore, following the XenBus convention.
+ *
+ * All data in the XenStore is stored as strings.  Nodes specifying numeric
+ * values are encoded in decimal.  Integer value ranges listed below are
+ * expressed as fixed sized integer types capable of storing the conversion
+ * of a properly formated node string, without loss of information.
+ *
+ * Any specified default value is in effect if the corresponding XenBus node
+ * is not present in the XenStore.
+ *
+ * XenStore nodes in sections marked "PRIVATE" are solely for use by the
+ * driver side whose XenBus tree contains them.
+ *
+ *****************************************************************************
+ *                            Backend XenBus Nodes
+ *****************************************************************************
+ *
+ *------------------ Backend Device Identification (PRIVATE) ------------------
+ *
+ * stream_id
+ *      Values:         <uint32_t>
+ *
+ *      Virtuelized stream number
+ *
+ *****************************************************************************
+ *                            Frontend XenBus Nodes
+ *****************************************************************************
+ *
+ *----------------------- Request Transport Parameters -----------------------
+ *
+ * event-channel
+ *      Values:         <uint32_t>
+ *
+ *      The identifier of the Xen event channel used to signal activity
+ *      in the ring buffer.
+ *
+ * ring-ref
+ *      Values:         <uint32_t>
+ *      Notes:          6
+ *
+ *      The Xen grant reference granting permission for the backend to map
+ *      the sole page in a single page sized ring buffer.
+ */
+
+/*
+ * PCM FORMATS.
+ */
+#define SNDIF_PCM_FORMAT_S8            (0)
+#define SNDIF_PCM_FORMAT_U8            (1)
+#define SNDIF_PCM_FORMAT_S16_LE                (2)
+#define SNDIF_PCM_FORMAT_S16_BE                (3)
+#define SNDIF_PCM_FORMAT_U16_LE                (4)
+#define SNDIF_PCM_FORMAT_U16_BE                (5)
+
+/* low three bytes */
+#define SNDIF_PCM_FORMAT_S24_LE                (6)
+
+/* low three bytes */
+#define SNDIF_PCM_FORMAT_S24_BE                (7)
+
+/* low three bytes */
+#define SNDIF_PCM_FORMAT_U24_LE                (8)
+
+/* low three bytes */
+#define SNDIF_PCM_FORMAT_U24_BE                (9)
+
+#define SNDIF_PCM_FORMAT_S32_LE                (10)
+#define SNDIF_PCM_FORMAT_S32_BE                (11)
+#define SNDIF_PCM_FORMAT_U32_LE                (12)
+#define SNDIF_PCM_FORMAT_U32_BE                (13)
+
+/* 4-byte float, IEEE-754 32-bit, range -1.0 to 1.0 */
+#define SNDIF_PCM_FORMAT_FLOAT_LE      (14)
+
+/* 4-byte float, IEEE-754 32-bit, range -1.0 to 1.0 */
+#define SNDIF_PCM_FORMAT_FLOAT_BE      (15)
+
+/* 8-byte float, IEEE-754 64-bit, range -1.0 to 1.0 */
+#define SNDIF_PCM_FORMAT_FLOAT64_LE    (16)
+
+/* 8-byte float, IEEE-754 64-bit, range -1.0 to 1.0 */
+#define SNDIF_PCM_FORMAT_FLOAT64_BE    (17)
+
+/* IEC-958 subframe, Little Endian */
+#define SNDIF_PCM_FORMAT_IEC958_SUBFRAME_LE (18)
+
+/* IEC-958 subframe, Big Endian */
+#define SNDIF_PCM_FORMAT_IEC958_SUBFRAME_BE (19)
+
+#define SNDIF_PCM_FORMAT_MU_LAW                (20)
+#define SNDIF_PCM_FORMAT_A_LAW         (21)
+#define SNDIF_PCM_FORMAT_IMA_ADPCM     (22)
+#define SNDIF_PCM_FORMAT_MPEG          (23)
+#define SNDIF_PCM_FORMAT_GSM           (24)
+#define SNDIF_PCM_FORMAT_SPECIAL       (31)
+
+/*
+ * REQUEST CODES.
+ */
+#define SNDIF_OP_OPEN                  0
+#define SNDIF_OP_CLOSE                 1
+#define SNDIF_OP_READ                  2
+#define SNDIF_OP_WRITE                 3
+#define SNDIF_SET_VOLUME               4
+#define SNDIF_GET_VOLUME               5
+
+#define SNDIF_MAX_PAGES_PER_REQUEST    10
+
+/*
+ * STATUS RETURN CODES.
+ */
+ /* Operation failed for some unspecified reason (-EIO). */
+#define SNDIF_RSP_ERROR       -1
+ /* Operation completed successfully. */
+#define SNDIF_RSP_OKAY         0
+
+struct snd_params {
+       uint32_t format;        /* SNDIF_PCM_FORMAT_??? */
+       uint32_t channels;      /* Channels count       */
+       uint32_t rate;          /* Data rate            */
+};
+
+struct sndif_request_common {
+       uint64_t id;            /* private guest value, echoed in resp  */
+       struct snd_params _pad1;
+       uint32_t _pad2;
+       uint32_t _pad3;
+};
+
+struct sndif_request_open {
+       uint64_t id;            /* private guest value, echoed in resp  */
+       struct snd_params snd_params;
+       uint32_t stream;
+       uint32_t _pad2;
+};
+
+struct sndif_request_rw {
+       uint64_t id;            /* private guest value, echoed in resp  */
+       struct snd_params _pad1;
+       uint32_t len;
+       uint32_t _pad2;
+       grant_ref_t gref[SNDIF_MAX_PAGES_PER_REQUEST];
+};
+
+struct sndif_request_volume {
+       uint64_t id;            /* private guest value, echoed in resp  */
+       struct snd_params _pad1;
+       uint32_t left;
+       uint32_t right;
+};
+
+struct sndif_request {
+       uint8_t operation;      /* SNDIF_OP_??? */
+       union {
+               struct sndif_request_common common;
+               struct sndif_request_open open;
+               struct sndif_request_rw rw;
+               struct sndif_request_volume vol;
+       } u;
+};
+
+struct sndif_response {
+       uint64_t id;            /* copied from request */
+       uint8_t operation;      /* copied from request */
+       int16_t status;         /* SNDIF_RSP_???       */
+};
+
+DEFINE_RING_TYPES(sndif, struct sndif_request, struct sndif_response);
+
+#endif /* __XEN_PUBLIC_IO_SNDIF_H__ */
diff --git a/sound/drivers/Kconfig b/sound/drivers/Kconfig
index 8545da9..cd3db5a 100644
--- a/sound/drivers/Kconfig
+++ b/sound/drivers/Kconfig
@@ -24,6 +24,16 @@ config SND_AC97_CODEC
        select AC97_BUS
        select SND_VMASTER
 
+config XEN_SND_FRONTEND
+       tristate "Xen virtual audio front-end driver support"
+       depends on SND && XEN_DOMU
+       default n
+       select SND_PCM
+       help
+         This driver implements the front-end of the Xen virtual
+         audio driver.  It communicates with a back-end
+         in another domain.
+
 menuconfig SND_DRIVERS
        bool "Generic sound devices"
        default y
diff --git a/sound/drivers/Makefile b/sound/drivers/Makefile
index 1a8440c..f9f7e19 100644
--- a/sound/drivers/Makefile
+++ b/sound/drivers/Makefile
@@ -11,6 +11,7 @@ snd-portman2x4-objs := portman2x4.o
 snd-serial-u16550-objs := serial-u16550.o
 snd-virmidi-objs := virmidi.o
 snd-ml403-ac97cr-objs := ml403-ac97cr.o pcm-indirect2.o
+xen-sndfrontend-objs := xen-sndfront.o
 
 # Toplevel Module Dependency
 obj-$(CONFIG_SND_DUMMY) += snd-dummy.o
@@ -21,5 +22,6 @@ obj-$(CONFIG_SND_MTPAV) += snd-mtpav.o
 obj-$(CONFIG_SND_MTS64) += snd-mts64.o
 obj-$(CONFIG_SND_PORTMAN2X4) += snd-portman2x4.o
 obj-$(CONFIG_SND_ML403_AC97CR) += snd-ml403-ac97cr.o
+obj-$(CONFIG_XEN_SND_FRONTEND) += xen-sndfrontend.o
 
 obj-$(CONFIG_SND) += opl3/ opl4/ mpu401/ vx/ pcsp/
diff --git a/sound/drivers/xen-sndfront.c b/sound/drivers/xen-sndfront.c
new file mode 100644
index 0000000..d0367c2
--- /dev/null
+++ b/sound/drivers/xen-sndfront.c
@@ -0,0 +1,1478 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation; or, when distributed
+ * separately from the Linux kernel or incorporated into other
+ * software packages, subject to the following license:
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this source file (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy, modify,
+ * merge, publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ *
+ * Copyright (C) 2013-2015 GlobalLogic Inc.
+ */
+
+#include <linux/init.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/jiffies.h>
+#include <linux/slab.h>
+#include <linux/time.h>
+#include <linux/wait.h>
+#include <linux/hrtimer.h>
+#include <linux/math64.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <sound/core.h>
+#include <sound/control.h>
+#include <sound/tlv.h>
+#include <sound/pcm.h>
+#include <sound/rawmidi.h>
+#include <sound/info.h>
+#include <sound/initval.h>
+
+#include <linux/uaccess.h>
+
+#include <xen/xen.h>
+#include <xen/events.h>
+#include <xen/page.h>
+#include <xen/grant_table.h>
+#include <xen/xenbus.h>
+#include <xen/interface/grant_table.h>
+
+#include <xen/interface/io/protocols.h>
+#include <xen/interface/io/sndif.h>
+
+MODULE_LICENSE("GPL");
+MODULE_SUPPORTED_DEVICE("{{ALSA,Virtual soundcard}}");
+
+#define VSND_WAIT_ANSWER_TOUT  5000
+
+#define MAX_PCM_DEVICES                1
+#define MAX_PCM_SUBSTREAMS     1
+#define MAX_BUFFER_SIZE                (64*1024)
+
+/* defaults */
+#define MIN_PERIOD_SIZE                64
+#define MAX_PERIOD_SIZE                (4*1024)
+#define USE_FORMATS            (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE)
+#define USE_RATE               (SNDRV_PCM_RATE_CONTINUOUS |\
+                                SNDRV_PCM_RATE_8000_48000)
+#define USE_RATE_MIN           5500
+#define USE_RATE_MAX           48000
+#define USE_CHANNELS_MIN       1
+#define USE_CHANNELS_MAX       2
+#define USE_PERIODS_MIN                1
+#define USE_PERIODS_MAX                1024
+
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;     /* Index 0-MAX */
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR;      /* ID for this card */
+static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
+static char *model[SNDRV_CARDS] = {[0 ... (SNDRV_CARDS - 1)] = NULL};
+
+module_param_array(index, int, NULL, 0444);
+MODULE_PARM_DESC(index, "Index value for virtual soundcard.");
+module_param_array(id, charp, NULL, 0444);
+MODULE_PARM_DESC(id, "ID string for virtual soundcard.");
+module_param_array(enable, bool, NULL, 0444);
+MODULE_PARM_DESC(enable, "Enable this virtual soundcard.");
+module_param_array(model, charp, NULL, 0444);
+MODULE_PARM_DESC(model, "Soundcard model.");
+
+#define MIXER_ADDR_MASTER_IN   0
+#define MIXER_ADDR_MASTER_OUT  1
+#define MIXER_ADDR_LAST                        MIXER_ADDR_MASTER_OUT
+
+struct vsnd_card {
+       struct sndfront_info *fr_info;
+       unsigned int stream_id;
+       grant_ref_t grefs[SNDIF_MAX_PAGES_PER_REQUEST];
+       unsigned char *buf;
+};
+
+#define SND_RING_SIZE __CONST_RING_SIZE(sndif, PAGE_SIZE)
+
+enum sndif_state {
+       SNDIF_STATE_DISCONNECTED,
+       SNDIF_STATE_CONNECTED,
+       SNDIF_STATE_SUSPENDED,
+};
+
+struct sndfront_info {
+       struct mutex mutex;             /* protect sndfront closing state */
+       struct completion completion;
+       spinlock_t io_lock;             /* protect 'connected' member */
+       struct xenbus_device *xbdev;
+       enum sndif_state connected;
+       int ring_ref;
+       struct sndif_front_ring ring;
+       unsigned int evtchn, irq;
+       struct vsnd_card *vcard;
+       int bret_code;
+       struct platform_device *card_dev;
+};
+
+#define GRANT_INVALID_REF      0
+
+struct virtualcard_model {
+       const char *name;
+       u64 formats;
+       size_t buffer_bytes_max;
+       size_t period_bytes_min;
+       size_t period_bytes_max;
+       unsigned int periods_min;
+       unsigned int periods_max;
+       unsigned int rates;
+       unsigned int rate_min;
+       unsigned int rate_max;
+       unsigned int channels_min;
+       unsigned int channels_max;
+};
+
+struct stream_info {
+       snd_pcm_uframes_t position;     /* Current position */
+       snd_pcm_uframes_t crossed;      /* Number of crossed writes*/
+       snd_pcm_format_t format;        /* SNDRV_PCM_FORMAT_* */
+       unsigned int rate;              /* rate in Hz */
+       unsigned int channels;          /* channels */
+       bool opened;                    /* opened status */
+};
+
+struct snd_virtualcard {
+       struct snd_card *card;
+       struct virtualcard_model *model;
+       struct snd_pcm *pcm;
+       struct snd_pcm_hardware pcm_hw;
+       spinlock_t mixer_lock;          /* protect mixer settings */
+       int mixer_volume[MIXER_ADDR_LAST+1][2];
+       int capture_source[MIXER_ADDR_LAST+1][2];
+       struct sndfront_info *fr_info;
+       struct stream_info streams[2];
+};
+
+/*
+ * card models
+ */
+
+struct virtualcard_model model_ac97 = {
+       .name = "ac97",
+       .formats = (SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE),
+       .channels_min = 1,
+       .channels_max = 2,
+       .rates = SNDRV_PCM_RATE_8000_48000,
+       .rate_min = 8000,
+       .rate_max = 48000,
+};
+
+struct virtualcard_model *virtualcard_models[] = {
+       &model_ac97,
+       NULL
+};
+
+/*
+ * PCM interface
+ */
+
+static struct snd_pcm_hardware virtualcard_pcm_hardware = {
+       .info =                 (SNDRV_PCM_INFO_MMAP |
+                                SNDRV_PCM_INFO_INTERLEAVED |
+                                SNDRV_PCM_INFO_RESUME |
+                                SNDRV_PCM_INFO_MMAP_VALID),
+       .formats =              USE_FORMATS,
+       .rates =                USE_RATE,
+       .rate_min =             USE_RATE_MIN,
+       .rate_max =             USE_RATE_MAX,
+       .channels_min =         USE_CHANNELS_MIN,
+       .channels_max =         USE_CHANNELS_MAX,
+       .buffer_bytes_max =     MAX_BUFFER_SIZE,
+       .period_bytes_min =     MIN_PERIOD_SIZE,
+       .period_bytes_max =     MAX_PERIOD_SIZE,
+       .periods_min =          USE_PERIODS_MIN,
+       .periods_max =          USE_PERIODS_MAX,
+       .fifo_size =            0,
+};
+
+static inline
+struct stream_info *get_vcard_stream(struct snd_virtualcard *virtualcard,
+                                    struct snd_pcm_substream *substream)
+{
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               return &virtualcard->streams[0];
+       else
+               return &virtualcard->streams[1];
+}
+
+static unsigned long vmalloc_to_mfn(void *address)
+{
+       return pfn_to_mfn(vmalloc_to_pfn(address));
+}
+
+static inline void flush_requests(struct sndfront_info *info)
+{
+       int notify;
+
+       RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
+
+       if (notify)
+               notify_remote_via_irq(info->irq);
+}
+
+static int sndif_queue_request_open(struct sndfront_info *info,
+                                   snd_pcm_format_t format,
+                                   unsigned int channels,
+                                   unsigned int rate)
+{
+       struct sndif_request *req;
+
+       if (unlikely(info->connected != SNDIF_STATE_CONNECTED))
+               return 1;
+
+       req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
+
+       req->operation = SNDIF_OP_OPEN;
+       req->u.open.id = info->vcard->stream_id;
+       req->u.open.snd_params.format = format;
+       req->u.open.snd_params.channels = channels;
+       req->u.open.snd_params.rate = rate;
+       info->ring.req_prod_pvt++;
+
+       flush_requests(info);
+       return 0;
+}
+
+static int sndif_queue_request_close(struct sndfront_info *info)
+{
+       struct sndif_request *req;
+
+       if (unlikely(info->connected != SNDIF_STATE_CONNECTED))
+               return 1;
+
+       req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
+
+       req->operation = SNDIF_OP_CLOSE;
+       req->u.open.id = info->vcard->stream_id;
+
+       info->ring.req_prod_pvt++;
+
+       flush_requests(info);
+       return 0;
+}
+
+static int sndif_queue_request_write(struct sndfront_info *info,
+                                    unsigned int len)
+{
+       struct sndif_request *req;
+       grant_ref_t *gref;
+       int i;
+
+       if (unlikely(info->connected != SNDIF_STATE_CONNECTED))
+               return 1;
+
+       req = RING_GET_REQUEST(&info->ring, info->ring.req_prod_pvt);
+
+       req->operation = SNDIF_OP_WRITE;
+       req->u.rw.id = info->vcard->stream_id;
+
+       req->u.rw.len = len;
+
+       gref = info->vcard->grefs;
+
+       for (i = 0; i < SNDIF_MAX_PAGES_PER_REQUEST; i++)
+               req->u.rw.gref[i] = gref[i];
+
+       info->ring.req_prod_pvt++;
+
+       flush_requests(info);
+       return 0;
+}
+
+static int alsa_pcm_open(struct sndfront_info *info,
+                        snd_pcm_format_t format,
+                        unsigned int channels,
+                        unsigned int rate)
+{
+       unsigned long answer_tout;
+
+       reinit_completion(&info->completion);
+
+       if (sndif_queue_request_open(info, format, channels, rate))
+               return -EIO;
+
+       answer_tout = msecs_to_jiffies(VSND_WAIT_ANSWER_TOUT);
+       if (wait_for_completion_interruptible_timeout(&info->completion,
+                                                     answer_tout) <= 0)
+               return -ETIMEDOUT;
+
+       return info->bret_code;
+}
+
+static int alsa_pcm_close(struct sndfront_info *info)
+{
+       unsigned long answer_tout;
+
+       reinit_completion(&info->completion);
+
+       if (sndif_queue_request_close(info))
+               return -EIO;
+
+       answer_tout = msecs_to_jiffies(VSND_WAIT_ANSWER_TOUT);
+       if (wait_for_completion_interruptible_timeout(&info->completion,
+                                                     answer_tout) <= 0)
+               return -ETIMEDOUT;
+
+       return info->bret_code;
+}
+
+static int alsa_pcm_write(struct sndfront_info *info, char __user *buf,
+                         int len)
+{
+       unsigned char *shared_data;
+       unsigned long answer_tout;
+
+       shared_data = info->vcard->buf;
+
+       if (len > PAGE_SIZE * SNDIF_MAX_PAGES_PER_REQUEST)
+               return -EFAULT;
+
+       if (copy_from_user(shared_data, buf, len))
+               return -EFAULT;
+
+       reinit_completion(&info->completion);
+
+       if (sndif_queue_request_write(info, len))
+               return -EIO;
+
+       answer_tout = msecs_to_jiffies(VSND_WAIT_ANSWER_TOUT);
+       if (wait_for_completion_interruptible_timeout(&info->completion,
+                                                     answer_tout) <= 0)
+               return -ETIMEDOUT;
+
+       return info->bret_code;
+}
+
+static int alsa_pcm_silence(struct sndfront_info *info, int len)
+{
+       unsigned char *shared_data;
+       unsigned long answer_tout;
+
+       shared_data = info->vcard->buf;
+
+       if (len > PAGE_SIZE * SNDIF_MAX_PAGES_PER_REQUEST)
+               return -EFAULT;
+
+       memset(shared_data, 0, len);
+
+       reinit_completion(&info->completion);
+
+       if (sndif_queue_request_write(info, len))
+               return -EIO;
+
+       answer_tout = msecs_to_jiffies(VSND_WAIT_ANSWER_TOUT);
+       if (wait_for_completion_interruptible_timeout(&info->completion,
+                                                     answer_tout) <= 0)
+               return -ETIMEDOUT;
+
+       return info->bret_code;
+}
+
+static int sndif_setup_vcard(struct sndfront_info *info)
+{
+       grant_ref_t gref_head;
+       unsigned long mfn;
+       int ref;
+       int i;
+       int ret;
+
+       info->vcard->buf = vmalloc(SNDIF_MAX_PAGES_PER_REQUEST * PAGE_SIZE);
+       if (!info->vcard->buf) {
+               ret = -ENOMEM;
+               goto err_ret;
+       }
+
+       ret = gnttab_alloc_grant_references(SNDIF_MAX_PAGES_PER_REQUEST,
+                                           &gref_head);
+       if (ret)
+               goto err_vstream_free_buf;
+
+       for (i = 0; i < SNDIF_MAX_PAGES_PER_REQUEST; i++) {
+               ref = gnttab_claim_grant_reference(&gref_head);
+               BUG_ON(ref == -ENOSPC);
+
+               mfn = vmalloc_to_mfn(info->vcard->buf + PAGE_SIZE * i);
+
+               gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id,
+                                               mfn, 0);
+
+               info->vcard->grefs[i] = ref;
+       }
+
+       gnttab_free_grant_references(gref_head);
+       return ret;
+
+err_vstream_free_buf:
+       vfree(info->vcard->buf);
+       for (i = 0; i < SNDIF_MAX_PAGES_PER_REQUEST; i++)
+               gnttab_end_foreign_access(info->vcard->grefs[i], 0, 0UL);
+
+       gnttab_free_grant_references(gref_head);
+err_ret:
+       return ret;
+}
+
+static void sndif_cleanup_vcard(struct sndfront_info *info)
+{
+       int i;
+
+       if (info->vcard->buf) {
+               vfree(info->vcard->buf);
+               for (i = 0; i < SNDIF_MAX_PAGES_PER_REQUEST; i++)
+                       gnttab_end_foreign_access(info->vcard->grefs[i],
+                                                 0, 0UL);
+       }
+}
+
+static int sndif_add_virt_devices(struct sndfront_info *info,
+                                 unsigned int stream_id)
+{
+       int ret = 0;
+
+       struct vsnd_card *vcard;
+
+       vcard = kmalloc(sizeof(*vcard), GFP_KERNEL);
+
+       if (!vcard)
+               return -ENOMEM;
+
+       vcard->stream_id = stream_id;
+       vcard->fr_info = info;
+
+       info->vcard = vcard;
+
+       sndif_setup_vcard(info);
+
+       return ret;
+}
+
+static void sndif_cleanup_virt_devices(struct sndfront_info *info)
+{
+       if (info->vcard) {
+               sndif_cleanup_vcard(info);
+               kfree(info->vcard);
+       }
+}
+
+static void sndif_free(struct sndfront_info *info, int suspend)
+{
+       /* Free resources associated with old device channel. */
+       if (info->ring_ref != GRANT_INVALID_REF) {
+               gnttab_end_foreign_access(info->ring_ref, 0,
+                                         (unsigned long)info->ring.sring);
+               info->ring_ref = GRANT_INVALID_REF;
+               info->ring.sring = NULL;
+       }
+       if (info->irq)
+               unbind_from_irqhandler(info->irq, info);
+       info->evtchn = 0;
+       info->irq = 0;
+}
+
+static irqreturn_t sndif_interrupt(int irq, void *data)
+{
+       struct sndif_response *bret;
+       RING_IDX i, rp;
+       unsigned long flags;
+       struct sndfront_info *info = (struct sndfront_info *)data;
+       int error;
+
+       spin_lock_irqsave(&info->io_lock, flags);
+
+       if (unlikely(info->connected != SNDIF_STATE_CONNECTED)) {
+               spin_unlock_irqrestore(&info->io_lock, flags);
+               return IRQ_HANDLED;
+       }
+
+ again:
+       rp = info->ring.sring->rsp_prod;
+       rmb(); /* Ensure we see queued responses up to 'rp'. */
+
+       for (i = info->ring.rsp_cons; i != rp; i++) {
+               unsigned long id;
+
+               bret = RING_GET_RESPONSE(&info->ring, i);
+               id   = bret->id;
+
+               error = (bret->status == SNDIF_RSP_OKAY) ? 0 : -EIO;
+               switch (bret->operation) {
+               case SNDIF_OP_OPEN:
+               case SNDIF_OP_CLOSE:
+               case SNDIF_OP_WRITE:
+                       if (unlikely(bret->status != SNDIF_RSP_OKAY))
+                               dev_dbg(&info->xbdev->dev,
+                                       "snddev data request error: %x\n",
+                                       bret->status);
+
+                       info->bret_code = bret->status;
+                       complete(&info->completion);
+                       break;
+
+               default:
+                       BUG();
+               }
+       }
+
+       info->ring.rsp_cons = i;
+
+       if (i != info->ring.req_prod_pvt) {
+               int more_to_do;
+
+               RING_FINAL_CHECK_FOR_RESPONSES(&info->ring, more_to_do);
+               if (more_to_do)
+                       goto again;
+       } else {
+               info->ring.sring->rsp_event = i + 1;
+       }
+
+       spin_unlock_irqrestore(&info->io_lock, flags);
+       return IRQ_HANDLED;
+}
+
+static int setup_sndring(struct xenbus_device *dev,
+                        struct sndfront_info *info)
+{
+       struct sndif_sring *sring;
+       int err;
+
+       info->ring_ref = GRANT_INVALID_REF;
+
+       sring = (struct sndif_sring *)__get_free_page(GFP_NOIO | __GFP_HIGH);
+       if (!sring) {
+               xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
+               return -ENOMEM;
+       }
+       SHARED_RING_INIT(sring);
+       FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
+
+       err = xenbus_grant_ring(dev, virt_to_mfn(info->ring.sring));
+       if (err < 0) {
+               free_page((unsigned long)sring);
+               info->ring.sring = NULL;
+               goto fail;
+       }
+       info->ring_ref = err;
+
+       err = xenbus_alloc_evtchn(dev, &info->evtchn);
+       if (err)
+               goto fail;
+
+       err = bind_evtchn_to_irqhandler(info->evtchn, sndif_interrupt, 0,
+                                       "sndif", info);
+       if (err <= 0) {
+               xenbus_dev_fatal(dev, err,
+                                "bind_evtchn_to_irqhandler failed");
+               goto fail;
+       }
+       info->irq = err;
+
+       return 0;
+fail:
+       sndif_free(info, 0);
+       return err;
+}
+
+/* Common code used when first setting up, and when resuming. */
+static int talk_to_sndback(struct xenbus_device *dev,
+                          struct sndfront_info *info)
+{
+       const char *message = NULL;
+       struct xenbus_transaction xbt;
+       int err;
+
+       /* Create shared ring, alloc event channel. */
+       err = setup_sndring(dev, info);
+       if (err)
+               goto out;
+
+again:
+       err = xenbus_transaction_start(&xbt);
+       if (err) {
+               xenbus_dev_fatal(dev, err, "starting transaction");
+               goto destroy_sndring;
+       }
+
+       err = xenbus_printf(xbt, dev->nodename,
+                           "ring-ref", "%u", info->ring_ref);
+       if (err) {
+               message = "writing ring-ref";
+               goto abort_transaction;
+       }
+       err = xenbus_printf(xbt, dev->nodename,
+                           "event-channel", "%u", info->evtchn);
+       if (err) {
+               message = "writing event-channel";
+               goto abort_transaction;
+       }
+
+       err = xenbus_transaction_end(xbt, 0);
+       if (err) {
+               if (err == -EAGAIN)
+                       goto again;
+               xenbus_dev_fatal(dev, err, "completing transaction");
+               goto destroy_sndring;
+       }
+
+       xenbus_switch_state(dev, XenbusStateInitialised);
+
+       return 0;
+
+ abort_transaction:
+       xenbus_transaction_end(xbt, 1);
+       if (message)
+               xenbus_dev_fatal(dev, err, "%s", message);
+ destroy_sndring:
+       sndif_free(info, 0);
+ out:
+       return err;
+}
+
+static int virtualcard_pcm_trigger(struct snd_pcm_substream *substream, int 
cmd)
+{
+       struct snd_pcm_runtime *runtime = substream->runtime;
+
+       switch (cmd) {
+       case SNDRV_PCM_TRIGGER_START:
+       case SNDRV_PCM_TRIGGER_RESUME:
+               runtime->stop_threshold = runtime->buffer_size + 1;
+               break;
+       case SNDRV_PCM_TRIGGER_STOP:
+       case SNDRV_PCM_TRIGGER_SUSPEND:
+               runtime->stop_threshold = runtime->buffer_size;
+               break;
+       }
+       return 0;
+}
+
+static int virtualcard_pcm_prepare(struct snd_pcm_substream *substream)
+{
+       int err;
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct stream_info *vcard_stream;
+
+       vcard_stream = get_vcard_stream(virtualcard, substream);
+
+       if ((runtime->rate != vcard_stream->rate) ||
+           (runtime->channels != vcard_stream->channels) ||
+           (runtime->format != vcard_stream->format)) {
+               if (vcard_stream->opened) {
+                       err = alsa_pcm_close(virtualcard->fr_info);
+                       if (err)
+                               return err;
+
+                       /* if closed successfully */
+                       vcard_stream->opened = false;
+               }
+               err = alsa_pcm_open(virtualcard->fr_info, runtime->format,
+                                   runtime->channels, runtime->rate);
+               if (err)
+                       return err;
+
+               /* if opened successfully */
+               vcard_stream->rate = runtime->rate;
+               vcard_stream->channels = runtime->channels;
+               vcard_stream->format = runtime->format;
+               vcard_stream->opened = true;
+       }
+       return 0;
+}
+
+static
+snd_pcm_uframes_t virtualcard_pcm_pointer(struct snd_pcm_substream *substream)
+{
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       snd_pcm_uframes_t buff_size = substream->runtime->buffer_size;
+       struct stream_info *vcard_stream;
+
+       vcard_stream = get_vcard_stream(virtualcard, substream);
+
+       if (vcard_stream->crossed) {
+               snd_pcm_uframes_t hw_base = substream->runtime->hw_ptr_base;
+
+               hw_base += buff_size;
+               if (hw_base >= substream->runtime->boundary)
+                       hw_base = 0;
+
+               substream->runtime->hw_ptr_base = hw_base;
+               vcard_stream->crossed = 0;
+       }
+       return vcard_stream->position;
+}
+
+static int virtualcard_pcm_hw_params(struct snd_pcm_substream *substream,
+                                    struct snd_pcm_hw_params *hw_params)
+{
+       return 0;
+}
+
+static int virtualcard_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+       return 0;
+}
+
+static int virtualcard_pcm_open(struct snd_pcm_substream *substream)
+{
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct stream_info *vcard_stream;
+
+       vcard_stream = get_vcard_stream(virtualcard, substream);
+
+       vcard_stream->channels = 0;
+       vcard_stream->rate = 0;
+       vcard_stream->position = 0;
+       vcard_stream->crossed = 0;
+       vcard_stream->format = 0;
+       vcard_stream->opened = false;
+
+       runtime->hw = virtualcard->pcm_hw;
+       runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP |
+                                     SNDRV_PCM_INFO_MMAP_VALID |
+                                     SNDRV_PCM_INFO_DOUBLE |
+                                     SNDRV_PCM_INFO_BATCH |
+                                     SNDRV_PCM_INFO_NONINTERLEAVED |
+                                     SNDRV_PCM_INFO_RESUME |
+                                     SNDRV_PCM_INFO_PAUSE);
+       runtime->hw.info |= SNDRV_PCM_INFO_INTERLEAVED;
+       return 0;
+}
+
+static int virtualcard_pcm_close(struct snd_pcm_substream *substream)
+{
+       int err;
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+
+       err = alsa_pcm_close(virtualcard->fr_info);
+       if (err)
+               return err;
+
+       get_vcard_stream(virtualcard, substream)->opened = false;
+
+       return 0;
+}
+
+static int virtualcard_pcm_playback_copy(struct snd_pcm_substream *substream,
+                                        int channel, snd_pcm_uframes_t pos,
+                                        void __user *src,
+                                        snd_pcm_uframes_t count)
+{
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct stream_info *vcard_stream = &virtualcard->streams[0];
+       snd_pcm_uframes_t stream_pos = vcard_stream->position;
+
+       vcard_stream->position = (stream_pos + count) % runtime->buffer_size;
+       vcard_stream->crossed = count / runtime->buffer_size;
+       return alsa_pcm_write(virtualcard->fr_info, src,
+                             frames_to_bytes(runtime, count));
+}
+
+static int virtualcard_pcm_playback_silence(struct snd_pcm_substream 
*substream,
+                                           int channel, snd_pcm_uframes_t pos,
+                                           snd_pcm_uframes_t count)
+{
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct stream_info *vcard_stream = &virtualcard->streams[0];
+       snd_pcm_uframes_t stream_pos = vcard_stream->position;
+
+       vcard_stream->position = (stream_pos + count) % runtime->buffer_size;
+       vcard_stream->crossed = count / runtime->buffer_size;
+
+       return alsa_pcm_silence(virtualcard->fr_info,
+                               frames_to_bytes(runtime, count));
+}
+
+static int virtualcard_pcm_capture_copy(struct snd_pcm_substream *substream,
+                                       int channel, snd_pcm_uframes_t pos,
+                                       void __user *dst,
+                                       snd_pcm_uframes_t count)
+{
+       struct snd_virtualcard *virtualcard = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct stream_info *vcard_stream = &virtualcard->streams[1];
+       snd_pcm_uframes_t stream_pos = vcard_stream->position;
+
+       vcard_stream->position = (stream_pos + count) % runtime->buffer_size;
+       vcard_stream->crossed = count / runtime->buffer_size;
+
+       return 0;
+}
+
+static struct snd_pcm_ops virtualcard_pcm_playback_ops = {
+       .open =         virtualcard_pcm_open,
+       .close =        virtualcard_pcm_close,
+       .ioctl =        snd_pcm_lib_ioctl,
+       .hw_params =    virtualcard_pcm_hw_params,
+       .hw_free =      virtualcard_pcm_hw_free,
+       .prepare =      virtualcard_pcm_prepare,
+       .trigger =      virtualcard_pcm_trigger,
+       .pointer =      virtualcard_pcm_pointer,
+       .copy =         virtualcard_pcm_playback_copy,
+       .silence =      virtualcard_pcm_playback_silence,
+};
+
+static struct snd_pcm_ops virtualcard_pcm_capture_ops = {
+       .open =         virtualcard_pcm_open,
+       .close =        virtualcard_pcm_close,
+       .ioctl =        snd_pcm_lib_ioctl,
+       .hw_params =    virtualcard_pcm_hw_params,
+       .hw_free =      virtualcard_pcm_hw_free,
+       .prepare =      virtualcard_pcm_prepare,
+       .trigger =      virtualcard_pcm_trigger,
+       .pointer =      virtualcard_pcm_pointer,
+       .copy =         virtualcard_pcm_capture_copy,
+};
+
+static int snd_card_virtualcard_pcm(struct snd_virtualcard *virtualcard,
+                                   int device, int substreams)
+{
+       struct snd_pcm *pcm;
+       int err;
+
+       err = snd_pcm_new(virtualcard->card, "Virtual card PCM", device,
+                         substreams, substreams, &pcm);
+       if (err < 0)
+               return err;
+       virtualcard->pcm = pcm;
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK,
+                       &virtualcard_pcm_playback_ops);
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE,
+                       &virtualcard_pcm_capture_ops);
+       pcm->private_data = virtualcard;
+       pcm->info_flags = 0;
+       strcpy(pcm->name, "Virtual card PCM");
+
+       return 0;
+}
+
+/*
+ * mixer interface
+ */
+
+#define VIRTUALCARD_VOLUME(xname, xindex, addr) {      \
+       .iface = SNDRV_CTL_ELEM_IFACE_MIXER,            \
+       .access = SNDRV_CTL_ELEM_ACCESS_READWRITE |     \
+                 SNDRV_CTL_ELEM_ACCESS_TLV_READ,       \
+       .name = xname,                                  \
+       .index = xindex,                                \
+       .info = snd_virtualcard_volume_info,            \
+       .get = snd_virtualcard_volume_get,              \
+       .put = snd_virtualcard_volume_put,              \
+       .private_value = addr,                          \
+       .tlv = { .p = db_scale_virtualcard }            \
+}
+
+static int snd_virtualcard_volume_info(struct snd_kcontrol *kcontrol,
+                                      struct snd_ctl_elem_info *uinfo)
+{
+       uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
+       uinfo->count = 2;
+       uinfo->value.integer.min = -50;
+       uinfo->value.integer.max = 100;
+       return 0;
+}
+
+static int snd_virtualcard_volume_get(struct snd_kcontrol *kcontrol,
+                                     struct snd_ctl_elem_value *ucontrol)
+{
+       struct snd_virtualcard *virtualcard = snd_kcontrol_chip(kcontrol);
+       int addr = kcontrol->private_value;
+
+       spin_lock_irq(&virtualcard->mixer_lock);
+       ucontrol->value.integer.value[0] = virtualcard->mixer_volume[addr][0];
+       ucontrol->value.integer.value[1] = virtualcard->mixer_volume[addr][1];
+       spin_unlock_irq(&virtualcard->mixer_lock);
+       return 0;
+}
+
+static int snd_virtualcard_volume_put(struct snd_kcontrol *kcontrol,
+                                     struct snd_ctl_elem_value *ucontrol)
+{
+       struct snd_virtualcard *virtualcard = snd_kcontrol_chip(kcontrol);
+       int change, addr = kcontrol->private_value;
+       int left, right;
+
+       left = ucontrol->value.integer.value[0];
+       if (left < -50)
+               left = -50;
+       if (left > 100)
+               left = 100;
+       right = ucontrol->value.integer.value[1];
+       if (right < -50)
+               right = -50;
+       if (right > 100)
+               right = 100;
+       spin_lock_irq(&virtualcard->mixer_lock);
+       change = virtualcard->mixer_volume[addr][0] != left ||
+                virtualcard->mixer_volume[addr][1] != right;
+       virtualcard->mixer_volume[addr][0] = left;
+       virtualcard->mixer_volume[addr][1] = right;
+       spin_unlock_irq(&virtualcard->mixer_lock);
+       return change;
+}
+
+static const DECLARE_TLV_DB_SCALE(db_scale_virtualcard, -4500, 30, 0);
+
+#define VIRTUALCARD_CAPSRC(xname, xindex, addr) {      \
+       .iface = SNDRV_CTL_ELEM_IFACE_MIXER,            \
+       .name = xname,                                  \
+       .index = xindex,                                \
+       .info = snd_virtualcard_capsrc_info,            \
+       .get = snd_virtualcard_capsrc_get,              \
+       .put = snd_virtualcard_capsrc_put,              \
+       .private_value = addr                           \
+}
+
+#define snd_virtualcard_capsrc_info    snd_ctl_boolean_stereo_info
+
+static int snd_virtualcard_capsrc_get(struct snd_kcontrol *kcontrol,
+                                     struct snd_ctl_elem_value *ucontrol)
+{
+       struct snd_virtualcard *virtualcard = snd_kcontrol_chip(kcontrol);
+       int addr = kcontrol->private_value;
+
+       spin_lock_irq(&virtualcard->mixer_lock);
+       ucontrol->value.integer.value[0] = virtualcard->capture_source[addr][0];
+       ucontrol->value.integer.value[1] = virtualcard->capture_source[addr][1];
+       spin_unlock_irq(&virtualcard->mixer_lock);
+       return 0;
+}
+
+static int snd_virtualcard_capsrc_put(struct snd_kcontrol *kcontrol,
+                                     struct snd_ctl_elem_value *ucontrol)
+{
+       struct snd_virtualcard *virtualcard = snd_kcontrol_chip(kcontrol);
+       int change, addr = kcontrol->private_value;
+       int left, right;
+
+       left = ucontrol->value.integer.value[0] & 1;
+       right = ucontrol->value.integer.value[1] & 1;
+       spin_lock_irq(&virtualcard->mixer_lock);
+       change = virtualcard->capture_source[addr][0] != left &&
+                virtualcard->capture_source[addr][1] != right;
+       virtualcard->capture_source[addr][0] = left;
+       virtualcard->capture_source[addr][1] = right;
+       spin_unlock_irq(&virtualcard->mixer_lock);
+       return change;
+}
+
+static struct snd_kcontrol_new snd_virtualcard_controls[] = {
+VIRTUALCARD_VOLUME("Master Out Volume", 0, MIXER_ADDR_MASTER_OUT),
+VIRTUALCARD_CAPSRC("Master Out Switch", 0, MIXER_ADDR_MASTER_OUT),
+VIRTUALCARD_VOLUME("Master In Volume", 0, MIXER_ADDR_MASTER_IN),
+VIRTUALCARD_CAPSRC("Master In Switch", 0, MIXER_ADDR_MASTER_IN),
+};
+
+static int snd_card_virtualcard_new_mixer(struct snd_virtualcard *virtualcard)
+{
+       struct snd_card *card = virtualcard->card;
+       struct snd_kcontrol *kcontrol;
+       unsigned int idx;
+       int err;
+
+       spin_lock_init(&virtualcard->mixer_lock);
+       strcpy(card->mixername, "Virtual card Mixer");
+
+       for (idx = 0; idx < ARRAY_SIZE(snd_virtualcard_controls); idx++) {
+               kcontrol = snd_ctl_new1(&snd_virtualcard_controls[idx],
+                                       virtualcard);
+               err = snd_ctl_add(card, kcontrol);
+               if (err < 0)
+                       return err;
+       }
+       return 0;
+}
+
+/* #define CONFIG_SND_DEBUG */
+/* #define CONFIG_PROC_FS */
+#if defined(CONFIG_SND_DEBUG) && defined(CONFIG_PROC_FS)
+/*
+ * proc interface
+ */
+static void print_formats(struct snd_virtualcard *virtualcard,
+                         struct snd_info_buffer *buffer)
+{
+       int i;
+
+       for (i = 0; i < SNDRV_PCM_FORMAT_LAST; i++) {
+               if (virtualcard->pcm_hw.formats & (1ULL << i))
+                       snd_iprintf(buffer, " %s", snd_pcm_format_name(i));
+       }
+}
+
+static void print_rates(struct snd_virtualcard *virtualcard,
+                       struct snd_info_buffer *buffer)
+{
+       static int rates[] = {
+               8000, 11025, 16000, 22050, 32000, 44100, 48000,
+               64000, 88200, 96000, 176400, 192000,
+       };
+       int i;
+
+       if (virtualcard->pcm_hw.rates & SNDRV_PCM_RATE_CONTINUOUS)
+               snd_iprintf(buffer, " continuous");
+       if (virtualcard->pcm_hw.rates & SNDRV_PCM_RATE_KNOT)
+               snd_iprintf(buffer, " knot");
+       for (i = 0; i < ARRAY_SIZE(rates); i++)
+               if (virtualcard->pcm_hw.rates & (1 << i))
+                       snd_iprintf(buffer, " %d", rates[i]);
+}
+
+#define get_virtualcard_int_ptr(virtualcard, ofs) \
+       (unsigned int *)((char *)&((virtualcard)->pcm_hw) + (ofs))
+#define get_virtualcard_ll_ptr(virtualcard, ofs) \
+       (unsigned long long *)((char *)&((virtualcard)->pcm_hw) + (ofs))
+
+struct virtualcard_hw_field {
+       const char *name;
+       const char *format;
+       unsigned int offset;
+       unsigned int size;
+};
+
+#define FIELD_ENTRY(item, fmt) {                               \
+       .name = #item,                                          \
+       .format = fmt,                                          \
+       .offset = offsetof(struct snd_pcm_hardware, item),      \
+       .size = sizeof(virtualcard_pcm_hardware.item)           \
+}
+
+static struct virtualcard_hw_field fields[] = {
+       FIELD_ENTRY(formats, "%#llx"),
+       FIELD_ENTRY(rates, "%#x"),
+       FIELD_ENTRY(rate_min, "%d"),
+       FIELD_ENTRY(rate_max, "%d"),
+       FIELD_ENTRY(channels_min, "%d"),
+       FIELD_ENTRY(channels_max, "%d"),
+       FIELD_ENTRY(buffer_bytes_max, "%ld"),
+       FIELD_ENTRY(period_bytes_min, "%ld"),
+       FIELD_ENTRY(period_bytes_max, "%ld"),
+       FIELD_ENTRY(periods_min, "%d"),
+       FIELD_ENTRY(periods_max, "%d"),
+};
+
+static void virtualcard_proc_read(struct snd_info_entry *entry,
+                                 struct snd_info_buffer *buffer)
+{
+       struct snd_virtualcard *virtualcard = entry->private_data;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(fields); i++) {
+               snd_iprintf(buffer, "%s ", fields[i].name);
+               if (fields[i].size == sizeof(int))
+                       snd_iprintf(buffer, fields[i].format,
+                                   *get_virtualcard_int_ptr(virtualcard,
+                                                            fields[i].offset));
+               else
+                       snd_iprintf(buffer, fields[i].format,
+                                   *get_virtualcard_ll_ptr(virtualcard,
+                                                           fields[i].offset));
+               if (!strcmp(fields[i].name, "formats"))
+                       print_formats(virtualcard, buffer);
+               else if (!strcmp(fields[i].name, "rates"))
+                       print_rates(virtualcard, buffer);
+               snd_iprintf(buffer, "\n");
+       }
+}
+
+static void virtualcard_proc_write(struct snd_info_entry *entry,
+                                  struct snd_info_buffer *buffer)
+{
+       struct snd_virtualcard *virtualcard = entry->private_data;
+       char line[64];
+
+       while (!snd_info_get_line(buffer, line, sizeof(line))) {
+               char item[20];
+               const char *ptr;
+               unsigned long long val;
+               unsigned int offset;
+               int i;
+
+               ptr = snd_info_get_str(item, line, sizeof(item));
+               for (i = 0; i < ARRAY_SIZE(fields); i++) {
+                       if (!strcmp(item, fields[i].name))
+                               break;
+               }
+               if (i >= ARRAY_SIZE(fields))
+                       continue;
+               snd_info_get_str(item, ptr, sizeof(item));
+               if (kstrtoull(item, 0, &val))
+                       continue;
+
+               offset = fields[i].offset;
+               if (fields[i].size == sizeof(int))
+                       *get_virtualcard_int_ptr(virtualcard, offset) = val;
+               else
+                       *get_virtualcard_ll_ptr(virtualcard, offset) = val;
+       }
+}
+
+static void virtualcard_proc_init(struct snd_virtualcard *chip)
+{
+       struct snd_info_entry *entry;
+
+       if (!snd_card_proc_new(chip->card, "virtualcard_pcm", &entry)) {
+               snd_info_set_text_ops(entry, chip, virtualcard_proc_read);
+               entry->c.text.write = virtualcard_proc_write;
+               entry->mode |= S_IWUSR;
+               entry->private_data = chip;
+       }
+}
+#else
+#define virtualcard_proc_init(x)
+#endif /* CONFIG_SND_DEBUG && CONFIG_PROC_FS */
+
+static int snd_virtualcard_probe(struct platform_device *devptr)
+{
+       struct snd_card *card;
+       struct snd_virtualcard *virtualcard;
+       struct virtualcard_model *m = NULL;
+       int err;
+       int dev = devptr->id;
+       struct snd_pcm_hardware *pcm_hw;
+
+       err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
+                          sizeof(struct snd_virtualcard), &card);
+       if (err < 0)
+               return err;
+       virtualcard = card->private_data;
+       virtualcard->card = card;
+       virtualcard->fr_info =
+               (*((struct sndfront_info **)devptr->dev.platform_data));
+
+       m = virtualcard_models[0];
+
+       err = snd_card_virtualcard_pcm(virtualcard, 0, 1);
+       if (err < 0)
+               goto __nodev;
+
+       virtualcard->pcm_hw = virtualcard_pcm_hardware;
+       pcm_hw = &virtualcard->pcm_hw;
+       if (m) {
+               if (m->formats)
+                       pcm_hw->formats = m->formats;
+               if (m->buffer_bytes_max)
+                       pcm_hw->buffer_bytes_max = m->buffer_bytes_max;
+               if (m->period_bytes_min)
+                       pcm_hw->period_bytes_min = m->period_bytes_min;
+               if (m->period_bytes_max)
+                       pcm_hw->period_bytes_max = m->period_bytes_max;
+               if (m->periods_min)
+                       pcm_hw->periods_min = m->periods_min;
+               if (m->periods_max)
+                       pcm_hw->periods_max = m->periods_max;
+               if (m->rates)
+                       pcm_hw->rates = m->rates;
+               if (m->rate_min)
+                       pcm_hw->rate_min = m->rate_min;
+               if (m->rate_max)
+                       pcm_hw->rate_max = m->rate_max;
+               if (m->channels_min)
+                       pcm_hw->channels_min = m->channels_min;
+               if (m->channels_max)
+                       pcm_hw->channels_max = m->channels_max;
+       }
+
+       err = snd_card_virtualcard_new_mixer(virtualcard);
+       if (err < 0)
+               goto __nodev;
+       strcpy(card->driver, "Virtual card");
+       strcpy(card->shortname, "Virtual card");
+       sprintf(card->longname, "Virtual card %i", dev + 1);
+
+       virtualcard_proc_init(virtualcard);
+
+       snd_card_set_dev(card, &devptr->dev);
+
+       err = snd_card_register(card);
+       if (err == 0) {
+               platform_set_drvdata(devptr, card);
+               return 0;
+       }
+__nodev:
+       snd_card_free(card);
+       return err;
+}
+
+static int snd_virtualcard_remove(struct platform_device *devptr)
+{
+       snd_card_free(platform_get_drvdata(devptr));
+       platform_set_drvdata(devptr, NULL);
+       return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int snd_virtualcard_suspend(struct device *pdev)
+{
+       struct snd_card *card = dev_get_drvdata(pdev);
+       struct snd_virtualcard *virtualcard = card->private_data;
+
+       snd_power_change_state(card, SNDRV_CTL_POWER_D3hot);
+       snd_pcm_suspend_all(virtualcard->pcm);
+       return 0;
+}
+
+static int snd_virtualcard_resume(struct device *pdev)
+{
+       struct snd_card *card = dev_get_drvdata(pdev);
+
+       snd_power_change_state(card, SNDRV_CTL_POWER_D0);
+       return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(snd_virtualcard_pm, snd_virtualcard_suspend,
+                        snd_virtualcard_resume);
+#define SND_VIRTUALCARD_PM_OPS (&snd_virtualcard_pm)
+#else
+#define SND_VIRTUALCARD_PM_OPS NULL
+#endif
+
+#define SND_VIRTUALCARD_DRIVER "snd_virtualcard"
+
+static struct platform_driver snd_virtualcard_driver = {
+       .probe          = snd_virtualcard_probe,
+       .remove         = snd_virtualcard_remove,
+       .driver         = {
+               .name   = SND_VIRTUALCARD_DRIVER,
+               .owner  = THIS_MODULE,
+               .pm     = SND_VIRTUALCARD_PM_OPS,
+       },
+};
+
+/**
+ * Entry point to this code when a new device is created.  Allocate the basic
+ * structures and the ring buffer for communication with the backend, and
+ * inform the backend of the appropriate details for those.  Switch to
+ * Initialised state.
+ */
+static int sndfront_probe(struct xenbus_device *dev,
+                         const struct xenbus_device_id *id)
+{
+       int err;
+       struct sndfront_info *info;
+
+       info = kzalloc(sizeof(*info), GFP_KERNEL);
+       if (!info) {
+               xenbus_dev_fatal(dev, -ENOMEM, "allocating info structure");
+               return -ENOMEM;
+       }
+
+       mutex_init(&info->mutex);
+       spin_lock_init(&info->io_lock);
+       init_completion(&info->completion);
+       info->xbdev = dev;
+
+       dev_set_drvdata(&dev->dev, info);
+
+       err = talk_to_sndback(dev, info);
+       if (err)
+               goto err_free_info;
+
+       info->card_dev = platform_device_register_data(NULL,
+                                                      SND_VIRTUALCARD_DRIVER,
+                                                      -1, &info, sizeof(info));
+       if (IS_ERR(info->card_dev)) {
+               err = -ENODEV;
+               goto err_free_info;
+       }
+       return 0;
+
+err_free_info:
+       kfree(info);
+       dev_set_drvdata(&dev->dev, NULL);
+       return err;
+}
+
+/**
+ * We are reconnecting to the backend, due to a suspend/resume, or a backend
+ * driver restart.  We tear down our blkif structure and recreate it, but
+ * leave the device-layer structures intact so that this is transparent to the
+ * rest of the kernel.
+ */
+static int sndfront_resume(struct xenbus_device *dev)
+{
+       struct sndfront_info *info = dev_get_drvdata(&dev->dev);
+       int err;
+
+       dev_dbg(&dev->dev, "sndfront_resume: %s\n", dev->nodename);
+
+       sndif_free(info, info->connected == SNDIF_STATE_CONNECTED);
+
+       err = talk_to_sndback(dev, info);
+       if (info->connected == SNDIF_STATE_SUSPENDED && !err)
+               info->connected = SNDIF_STATE_CONNECTED;
+
+       return err;
+}
+
+static void
+sndfront_closing(struct sndfront_info *info)
+{
+       struct xenbus_device *xbdev = info->xbdev;
+
+       mutex_lock(&info->mutex);
+
+       if (xbdev->state == XenbusStateClosing) {
+               mutex_unlock(&info->mutex);
+               return;
+       }
+
+       mutex_unlock(&info->mutex);
+
+       xenbus_frontend_closed(xbdev);
+       sndif_cleanup_virt_devices(info);
+}
+
+/*
+ * Invoked when the backend is finally 'ready' (and has told produced
+ * the details about the physical device - #sectors, size, etc).
+ */
+static void sndfront_connect(struct sndfront_info *info)
+{
+       unsigned int stream_id;
+       int err;
+
+       switch (info->connected) {
+       case SNDIF_STATE_CONNECTED:
+
+               /* fall through */
+       case SNDIF_STATE_SUSPENDED:
+               return;
+
+       default:
+               break;
+       }
+
+       dev_dbg(&info->xbdev->dev, "%s:%s.\n",
+               __func__, info->xbdev->otherend);
+
+       xenbus_switch_state(info->xbdev, XenbusStateConnected);
+
+       err = xenbus_gather(XBT_NIL, info->xbdev->otherend, "stream_id", "%u",
+                           &stream_id, NULL);
+       if (err)
+               return;
+
+       err = sndif_add_virt_devices(info, stream_id);
+       if (err)
+               return;
+
+       spin_lock_irq(&info->io_lock);
+       info->connected = SNDIF_STATE_CONNECTED;
+       spin_unlock_irq(&info->io_lock);
+}
+
+/**
+ * Callback received when the backend's state changes.
+ */
+static void sndback_changed(struct xenbus_device *dev,
+                           enum xenbus_state backend_state)
+{
+       struct sndfront_info *info = dev_get_drvdata(&dev->dev);
+
+       dev_dbg(&dev->dev, "sndfront:sndback_changed to state %d.\n",
+               backend_state);
+
+       switch (backend_state) {
+       case XenbusStateInitialising:
+       case XenbusStateInitWait:
+       case XenbusStateInitialised:
+       case XenbusStateReconfiguring:
+       case XenbusStateReconfigured:
+       case XenbusStateUnknown:
+       case XenbusStateClosed:
+               break;
+
+       case XenbusStateConnected:
+               sndfront_connect(info);
+               break;
+
+       case XenbusStateClosing:
+               sndfront_closing(info);
+               break;
+       }
+}
+
+static int sndfront_remove(struct xenbus_device *xbdev)
+{
+       struct sndfront_info *info = dev_get_drvdata(&xbdev->dev);
+
+       dev_dbg(&xbdev->dev, "%s removed", xbdev->nodename);
+
+       platform_device_unregister(info->card_dev);
+
+       sndif_free(info, 0);
+
+       return 0;
+}
+
+static const struct xenbus_device_id xen_snd_ids[] = {
+       { "vsnd" },
+       { "" }
+};
+
+static struct xenbus_driver xen_snd_driver = {
+       .name = "xensnd",
+       .ids = xen_snd_ids,
+       .probe = sndfront_probe,
+       .remove = sndfront_remove,
+       .resume = sndfront_resume,
+       .otherend_changed = sndback_changed,
+};
+
+static int __init xen_snd_front_init(void)
+{
+       int ret = 0;
+
+       /*FIXME: xen_pv_domain() should be here, but ARM hardcoded to hvm*/
+       if (!xen_domain())
+               return -ENODEV;
+
+       /* Nothing to do if running in dom0. */
+       if (xen_initial_domain())
+               return -ENODEV;
+
+       ret = xenbus_register_frontend(&xen_snd_driver);
+       if (ret)
+               return ret;
+
+       ret = platform_driver_register(&snd_virtualcard_driver);
+
+       return ret;
+}
+
+static void __exit xen_snd_front_cleanup(void)
+{
+       xenbus_unregister_driver(&xen_snd_driver);
+       platform_driver_unregister(&snd_virtualcard_driver);
+}
+
+module_init(xen_snd_front_init);
+module_exit(xen_snd_front_cleanup);
+
+MODULE_DESCRIPTION("Xen virtual audio device frontend");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("xen:vsnd");
-- 
1.9.1


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