Add M2Tech hiFace USB-SPDIF driver

Add driver for M2Tech hiFace USB-SPDIF interface and compatible devices.

M2Tech hiFace and compatible devices offer a Hi-End S/PDIF Output
Interface, see http://www.m2tech.biz/hiface.html

The supported products are:

  * M2Tech Young
  * M2Tech hiFace
  * M2Tech North Star
  * M2Tech W4S Young
  * M2Tech Corrson
  * M2Tech AUDIA
  * M2Tech SL Audio
  * M2Tech Empirical
  * M2Tech Rockna
  * M2Tech Pathos
  * M2Tech Metronome
  * M2Tech CAD
  * M2Tech Audio Esclusive
  * M2Tech Rotel
  * M2Tech Eeaudio
  * The Chord Company CHORD
  * AVA Group A/S Vitus

Signed-off-by: Antonio Ospite <ao2@amarulasolutions.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

7 files changed, 1006 insertions, 1 deletions

diff --git a/sound/usb/Kconfig b/sound/usb/Kconfig
index 225dfd7..de9408b 100644
--- a/sound/usb/Kconfig
+++ b/sound/usb/Kconfig
@@ -115,5 +115,36 @@ config SND_USB_6FIRE
           and further help can be found at
           http://sixfireusb.sourceforge.net
 
+config SND_USB_HIFACE
+        tristate "M2Tech hiFace USB-SPDIF driver"
+        select SND_PCM
+        help
+	  Select this option to include support for M2Tech hiFace USB-SPDIF
+	  interface.
+
+	  This driver supports the original M2Tech hiFace and some other
+	  compatible devices. The supported products are:
+
+	    * M2Tech Young
+	    * M2Tech hiFace
+	    * M2Tech North Star
+	    * M2Tech W4S Young
+	    * M2Tech Corrson
+	    * M2Tech AUDIA
+	    * M2Tech SL Audio
+	    * M2Tech Empirical
+	    * M2Tech Rockna
+	    * M2Tech Pathos
+	    * M2Tech Metronome
+	    * M2Tech CAD
+	    * M2Tech Audio Esclusive
+	    * M2Tech Rotel
+	    * M2Tech Eeaudio
+	    * The Chord Company CHORD
+	    * AVA Group A/S Vitus
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called snd-usb-hiface.
+
 endif	# SND_USB
 
diff --git a/sound/usb/Makefile b/sound/usb/Makefile
index ac256dc..abe668f 100644
--- a/sound/usb/Makefile
+++ b/sound/usb/Makefile
@@ -23,4 +23,4 @@ obj-$(CONFIG_SND_USB_UA101) += snd-usbmidi-lib.o
 obj-$(CONFIG_SND_USB_USX2Y) += snd-usbmidi-lib.o
 obj-$(CONFIG_SND_USB_US122L) += snd-usbmidi-lib.o
 
-obj-$(CONFIG_SND) += misc/ usx2y/ caiaq/ 6fire/
+obj-$(CONFIG_SND) += misc/ usx2y/ caiaq/ 6fire/ hiface/
diff --git a/sound/usb/hiface/Makefile b/sound/usb/hiface/Makefile
new file mode 100644
index 0000000..463b136
--- /dev/null
+++ b/sound/usb/hiface/Makefile
@@ -0,0 +1,2 @@
+snd-usb-hiface-objs := chip.o pcm.o
+obj-$(CONFIG_SND_USB_HIFACE) += snd-usb-hiface.o
diff --git a/sound/usb/hiface/chip.c b/sound/usb/hiface/chip.c
new file mode 100644
index 0000000..b0dcb39
--- /dev/null
+++ b/sound/usb/hiface/chip.c
@@ -0,0 +1,297 @@
+/*
+ * Linux driver for M2Tech hiFace compatible devices
+ *
+ * Copyright 2012-2013 (C) M2TECH S.r.l and Amarula Solutions B.V.
+ *
+ * Authors:  Michael Trimarchi <michael@amarulasolutions.com>
+ *           Antonio Ospite <ao2@amarulasolutions.com>
+ *
+ * The driver is based on the work done in TerraTec DMX 6Fire USB
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <sound/initval.h>
+
+#include "chip.h"
+#include "pcm.h"
+
+MODULE_AUTHOR("Michael Trimarchi <michael@amarulasolutions.com>");
+MODULE_AUTHOR("Antonio Ospite <ao2@amarulasolutions.com>");
+MODULE_DESCRIPTION("M2Tech hiFace USB-SPDIF audio driver");
+MODULE_LICENSE("GPL v2");
+MODULE_SUPPORTED_DEVICE("{{M2Tech,Young},"
+			 "{M2Tech,hiFace},"
+			 "{M2Tech,North Star},"
+			 "{M2Tech,W4S Young},"
+			 "{M2Tech,Corrson},"
+			 "{M2Tech,AUDIA},"
+			 "{M2Tech,SL Audio},"
+			 "{M2Tech,Empirical},"
+			 "{M2Tech,Rockna},"
+			 "{M2Tech,Pathos},"
+			 "{M2Tech,Metronome},"
+			 "{M2Tech,CAD},"
+			 "{M2Tech,Audio Esclusive},"
+			 "{M2Tech,Rotel},"
+			 "{M2Tech,Eeaudio},"
+			 "{The Chord Company,CHORD},"
+			 "{AVA Group A/S,Vitus}}");
+
+static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-max */
+static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* Id for card */
+static bool enable[SNDRV_CARDS] = SNDRV_DEFAULT_ENABLE_PNP; /* Enable this card */
+
+#define DRIVER_NAME "snd-usb-hiface"
+#define CARD_NAME "hiFace"
+
+module_param_array(index, int, NULL, 0444);
+MODULE_PARM_DESC(index, "Index value for " CARD_NAME " soundcard.");
+module_param_array(id, charp, NULL, 0444);
+MODULE_PARM_DESC(id, "ID string for " CARD_NAME " soundcard.");
+module_param_array(enable, bool, NULL, 0444);
+MODULE_PARM_DESC(enable, "Enable " CARD_NAME " soundcard.");
+
+static DEFINE_MUTEX(register_mutex);
+
+struct hiface_vendor_quirk {
+	const char *device_name;
+	u8 extra_freq;
+};
+
+static int hiface_chip_create(struct usb_device *device, int idx,
+			      const struct hiface_vendor_quirk *quirk,
+			      struct hiface_chip **rchip)
+{
+	struct snd_card *card = NULL;
+	struct hiface_chip *chip;
+	int ret;
+	int len;
+
+	*rchip = NULL;
+
+	/* if we are here, card can be registered in alsa. */
+	ret = snd_card_create(index[idx], id[idx], THIS_MODULE, sizeof(*chip), &card);
+	if (ret < 0) {
+		dev_err(&device->dev, "cannot create alsa card.\n");
+		return ret;
+	}
+
+	strlcpy(card->driver, DRIVER_NAME, sizeof(card->driver));
+
+	if (quirk && quirk->device_name)
+		strlcpy(card->shortname, quirk->device_name, sizeof(card->shortname));
+	else
+		strlcpy(card->shortname, "M2Tech generic audio", sizeof(card->shortname));
+
+	strlcat(card->longname, card->shortname, sizeof(card->longname));
+	len = strlcat(card->longname, " at ", sizeof(card->longname));
+	if (len < sizeof(card->longname))
+		usb_make_path(device, card->longname + len,
+			      sizeof(card->longname) - len);
+
+	chip = card->private_data;
+	chip->dev = device;
+	chip->card = card;
+
+	*rchip = chip;
+	return 0;
+}
+
+static int hiface_chip_probe(struct usb_interface *intf,
+			     const struct usb_device_id *usb_id)
+{
+	const struct hiface_vendor_quirk *quirk = (struct hiface_vendor_quirk *)usb_id->driver_info;
+	int ret;
+	int i;
+	struct hiface_chip *chip;
+	struct usb_device *device = interface_to_usbdev(intf);
+
+	ret = usb_set_interface(device, 0, 0);
+	if (ret != 0) {
+		dev_err(&device->dev, "can't set first interface for " CARD_NAME " device.\n");
+		return -EIO;
+	}
+
+	/* check whether the card is already registered */
+	chip = NULL;
+	mutex_lock(&register_mutex);
+
+	for (i = 0; i < SNDRV_CARDS; i++)
+		if (enable[i])
+			break;
+
+	if (i >= SNDRV_CARDS) {
+		dev_err(&device->dev, "no available " CARD_NAME " audio device\n");
+		ret = -ENODEV;
+		goto err;
+	}
+
+	ret = hiface_chip_create(device, i, quirk, &chip);
+	if (ret < 0)
+		goto err;
+
+	snd_card_set_dev(chip->card, &intf->dev);
+
+	ret = hiface_pcm_init(chip, quirk ? quirk->extra_freq : 0);
+	if (ret < 0)
+		goto err_chip_destroy;
+
+	ret = snd_card_register(chip->card);
+	if (ret < 0) {
+		dev_err(&device->dev, "cannot register " CARD_NAME " card\n");
+		goto err_chip_destroy;
+	}
+
+	mutex_unlock(&register_mutex);
+
+	usb_set_intfdata(intf, chip);
+	return 0;
+
+err_chip_destroy:
+	snd_card_free(chip->card);
+err:
+	mutex_unlock(&register_mutex);
+	return ret;
+}
+
+static void hiface_chip_disconnect(struct usb_interface *intf)
+{
+	struct hiface_chip *chip;
+	struct snd_card *card;
+
+	chip = usb_get_intfdata(intf);
+	if (!chip)
+		return;
+
+	card = chip->card;
+
+	/* Make sure that the userspace cannot create new request */
+	snd_card_disconnect(card);
+
+	hiface_pcm_abort(chip);
+	snd_card_free_when_closed(card);
+}
+
+static const struct usb_device_id device_table[] = {
+	{
+		USB_DEVICE(0x04b4, 0x0384),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Young",
+			.extra_freq = 1,
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x930b),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "hiFace",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x931b),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "North Star",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x931c),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "W4S Young",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x931d),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Corrson",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x931e),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "AUDIA",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x931f),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "SL Audio",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x9320),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Empirical",
+		}
+	},
+	{
+		USB_DEVICE(0x04b4, 0x9321),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Rockna",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x9001),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Pathos",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x9002),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Metronome",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x9006),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "CAD",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x9008),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Audio Esclusive",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x931c),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Rotel",
+		}
+	},
+	{
+		USB_DEVICE(0x249c, 0x932c),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Eeaudio",
+		}
+	},
+	{
+		USB_DEVICE(0x245f, 0x931c),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "CHORD",
+		}
+	},
+	{
+		USB_DEVICE(0x25c6, 0x9002),
+		.driver_info = (unsigned long)&(const struct hiface_vendor_quirk) {
+			.device_name = "Vitus",
+		}
+	},
+	{}
+};
+
+MODULE_DEVICE_TABLE(usb, device_table);
+
+static struct usb_driver hiface_usb_driver = {
+	.name = DRIVER_NAME,
+	.probe = hiface_chip_probe,
+	.disconnect = hiface_chip_disconnect,
+	.id_table = device_table,
+};
+
+module_usb_driver(hiface_usb_driver);
diff --git a/sound/usb/hiface/chip.h b/sound/usb/hiface/chip.h
new file mode 100644
index 0000000..189a137
--- /dev/null
+++ b/sound/usb/hiface/chip.h
@@ -0,0 +1,30 @@
+/*
+ * Linux driver for M2Tech hiFace compatible devices
+ *
+ * Copyright 2012-2013 (C) M2TECH S.r.l and Amarula Solutions B.V.
+ *
+ * Authors:  Michael Trimarchi <michael@amarulasolutions.com>
+ *           Antonio Ospite <ao2@amarulasolutions.com>
+ *
+ * The driver is based on the work done in TerraTec DMX 6Fire USB
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef HIFACE_CHIP_H
+#define HIFACE_CHIP_H
+
+#include <linux/usb.h>
+#include <sound/core.h>
+
+struct pcm_runtime;
+
+struct hiface_chip {
+	struct usb_device *dev;
+	struct snd_card *card;
+	struct pcm_runtime *pcm;
+};
+#endif /* HIFACE_CHIP_H */
diff --git a/sound/usb/hiface/pcm.c b/sound/usb/hiface/pcm.c
new file mode 100644
index 0000000..6430ed2
--- /dev/null
+++ b/sound/usb/hiface/pcm.c
@@ -0,0 +1,621 @@
+/*
+ * Linux driver for M2Tech hiFace compatible devices
+ *
+ * Copyright 2012-2013 (C) M2TECH S.r.l and Amarula Solutions B.V.
+ *
+ * Authors:  Michael Trimarchi <michael@amarulasolutions.com>
+ *           Antonio Ospite <ao2@amarulasolutions.com>
+ *
+ * The driver is based on the work done in TerraTec DMX 6Fire USB
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/slab.h>
+#include <sound/pcm.h>
+
+#include "pcm.h"
+#include "chip.h"
+
+#define OUT_EP          0x2
+#define PCM_N_URBS      8
+#define PCM_PACKET_SIZE 4096
+#define PCM_BUFFER_SIZE (2 * PCM_N_URBS * PCM_PACKET_SIZE)
+
+struct pcm_urb {
+	struct hiface_chip *chip;
+
+	struct urb instance;
+	struct usb_anchor submitted;
+	u8 *buffer;
+};
+
+struct pcm_substream {
+	spinlock_t lock;
+	struct snd_pcm_substream *instance;
+
+	bool active;
+	snd_pcm_uframes_t dma_off;    /* current position in alsa dma_area */
+	snd_pcm_uframes_t period_off; /* current position in current period */
+};
+
+enum { /* pcm streaming states */
+	STREAM_DISABLED, /* no pcm streaming */
+	STREAM_STARTING, /* pcm streaming requested, waiting to become ready */
+	STREAM_RUNNING,  /* pcm streaming running */
+	STREAM_STOPPING
+};
+
+struct pcm_runtime {
+	struct hiface_chip *chip;
+	struct snd_pcm *instance;
+
+	struct pcm_substream playback;
+	bool panic; /* if set driver won't do anymore pcm on device */
+
+	struct pcm_urb out_urbs[PCM_N_URBS];
+
+	struct mutex stream_mutex;
+	u8 stream_state; /* one of STREAM_XXX */
+	u8 extra_freq;
+	wait_queue_head_t stream_wait_queue;
+	bool stream_wait_cond;
+};
+
+static const unsigned int rates[] = { 44100, 48000, 88200, 96000, 176400, 192000,
+				      352800, 384000 };
+static const struct snd_pcm_hw_constraint_list constraints_extra_rates = {
+	.count = ARRAY_SIZE(rates),
+	.list = rates,
+	.mask = 0,
+};
+
+static const struct snd_pcm_hardware pcm_hw = {
+	.info = SNDRV_PCM_INFO_MMAP |
+		SNDRV_PCM_INFO_INTERLEAVED |
+		SNDRV_PCM_INFO_BLOCK_TRANSFER |
+		SNDRV_PCM_INFO_PAUSE |
+		SNDRV_PCM_INFO_MMAP_VALID |
+		SNDRV_PCM_INFO_BATCH,
+
+	.formats = SNDRV_PCM_FMTBIT_S32_LE,
+
+	.rates = SNDRV_PCM_RATE_44100 |
+		SNDRV_PCM_RATE_48000 |
+		SNDRV_PCM_RATE_88200 |
+		SNDRV_PCM_RATE_96000 |
+		SNDRV_PCM_RATE_176400 |
+		SNDRV_PCM_RATE_192000,
+
+	.rate_min = 44100,
+	.rate_max = 192000, /* changes in hiface_pcm_open to support extra rates */
+	.channels_min = 2,
+	.channels_max = 2,
+	.buffer_bytes_max = PCM_BUFFER_SIZE,
+	.period_bytes_min = PCM_PACKET_SIZE,
+	.period_bytes_max = PCM_BUFFER_SIZE,
+	.periods_min = 2,
+	.periods_max = 1024
+};
+
+/* message values used to change the sample rate */
+#define HIFACE_SET_RATE_REQUEST 0xb0
+
+#define HIFACE_RATE_44100  0x43
+#define HIFACE_RATE_48000  0x4b
+#define HIFACE_RATE_88200  0x42
+#define HIFACE_RATE_96000  0x4a
+#define HIFACE_RATE_176400 0x40
+#define HIFACE_RATE_192000 0x48
+#define HIFACE_RATE_352000 0x58
+#define HIFACE_RATE_384000 0x68
+
+static int hiface_pcm_set_rate(struct pcm_runtime *rt, unsigned int rate)
+{
+	struct usb_device *device = rt->chip->dev;
+	u16 rate_value;
+	int ret;
+
+	/* We are already sure that the rate is supported here thanks to
+	 * ALSA constraints
+	 */
+	switch (rate) {
+	case 44100:
+		rate_value = HIFACE_RATE_44100;
+		break;
+	case 48000:
+		rate_value = HIFACE_RATE_48000;
+		break;
+	case 88200:
+		rate_value = HIFACE_RATE_88200;
+		break;
+	case 96000:
+		rate_value = HIFACE_RATE_96000;
+		break;
+	case 176400:
+		rate_value = HIFACE_RATE_176400;
+		break;
+	case 192000:
+		rate_value = HIFACE_RATE_192000;
+		break;
+	case 352000:
+		rate_value = HIFACE_RATE_352000;
+		break;
+	case 384000:
+		rate_value = HIFACE_RATE_384000;
+		break;
+	default:
+		dev_err(&device->dev, "Unsupported rate %d\n", rate);
+		return -EINVAL;
+	}
+
+	/*
+	 * USBIO: Vendor 0xb0(wValue=0x0043, wIndex=0x0000)
+	 * 43 b0 43 00 00 00 00 00
+	 * USBIO: Vendor 0xb0(wValue=0x004b, wIndex=0x0000)
+	 * 43 b0 4b 00 00 00 00 00
+	 * This control message doesn't have any ack from the
+	 * other side
+	 */
+	ret = usb_control_msg(device, usb_sndctrlpipe(device, 0),
+			      HIFACE_SET_RATE_REQUEST,
+			      USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_OTHER,
+			      rate_value, 0, NULL, 0, 100);
+	if (ret < 0) {
+		dev_err(&device->dev, "Error setting samplerate %d.\n", rate);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct pcm_substream *hiface_pcm_get_substream(struct snd_pcm_substream
+						      *alsa_sub)
+{
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+	struct device *device = &rt->chip->dev->dev;
+
+	if (alsa_sub->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		return &rt->playback;
+
+	dev_err(device, "Error getting pcm substream slot.\n");
+	return NULL;
+}
+
+/* call with stream_mutex locked */
+static void hiface_pcm_stream_stop(struct pcm_runtime *rt)
+{
+	int i, time;
+
+	if (rt->stream_state != STREAM_DISABLED) {
+		rt->stream_state = STREAM_STOPPING;
+
+		for (i = 0; i < PCM_N_URBS; i++) {
+			time = usb_wait_anchor_empty_timeout(
+					&rt->out_urbs[i].submitted, 100);
+			if (!time)
+				usb_kill_anchored_urbs(
+					&rt->out_urbs[i].submitted);
+			usb_kill_urb(&rt->out_urbs[i].instance);
+		}
+
+		rt->stream_state = STREAM_DISABLED;
+	}
+}
+
+/* call with stream_mutex locked */
+static int hiface_pcm_stream_start(struct pcm_runtime *rt)
+{
+	int ret = 0;
+	int i;
+
+	if (rt->stream_state == STREAM_DISABLED) {
+
+		/* reset panic state when starting a new stream */
+		rt->panic = false;
+
+		/* submit our out urbs zero init */
+		rt->stream_state = STREAM_STARTING;
+		for (i = 0; i < PCM_N_URBS; i++) {
+			memset(rt->out_urbs[i].buffer, 0, PCM_PACKET_SIZE);
+			usb_anchor_urb(&rt->out_urbs[i].instance,
+				       &rt->out_urbs[i].submitted);
+			ret = usb_submit_urb(&rt->out_urbs[i].instance,
+					     GFP_ATOMIC);
+			if (ret) {
+				hiface_pcm_stream_stop(rt);
+				return ret;
+			}
+		}
+
+		/* wait for first out urb to return (sent in in urb handler) */
+		wait_event_timeout(rt->stream_wait_queue, rt->stream_wait_cond,
+				   HZ);
+		if (rt->stream_wait_cond) {
+			struct device *device = &rt->chip->dev->dev;
+			dev_dbg(device, "%s: Stream is running wakeup event\n",
+				 __func__);
+			rt->stream_state = STREAM_RUNNING;
+		} else {
+			hiface_pcm_stream_stop(rt);
+			return -EIO;
+		}
+	}
+	return ret;
+}
+
+/* The hardware wants word-swapped 32-bit values */
+static void memcpy_swahw32(u8 *dest, u8 *src, unsigned int n)
+{
+	unsigned int i;
+
+	for (i = 0; i < n / 4; i++)
+		((u32 *)dest)[i] = swahw32(((u32 *)src)[i]);
+}
+
+/* call with substream locked */
+/* returns true if a period elapsed */
+static bool hiface_pcm_playback(struct pcm_substream *sub, struct pcm_urb *urb)
+{
+	struct snd_pcm_runtime *alsa_rt = sub->instance->runtime;
+	struct device *device = &urb->chip->dev->dev;
+	u8 *source;
+	unsigned int pcm_buffer_size;
+
+	WARN_ON(alsa_rt->format != SNDRV_PCM_FORMAT_S32_LE);
+
+	pcm_buffer_size = snd_pcm_lib_buffer_bytes(sub->instance);
+
+	if (sub->dma_off + PCM_PACKET_SIZE <= pcm_buffer_size) {
+		dev_dbg(device, "%s: (1) buffer_size %#x dma_offset %#x\n", __func__,
+			 (unsigned int) pcm_buffer_size,
+			 (unsigned int) sub->dma_off);
+
+		source = alsa_rt->dma_area + sub->dma_off;
+		memcpy_swahw32(urb->buffer, source, PCM_PACKET_SIZE);
+	} else {
+		/* wrap around at end of ring buffer */
+		unsigned int len;
+
+		dev_dbg(device, "%s: (2) buffer_size %#x dma_offset %#x\n", __func__,
+			 (unsigned int) pcm_buffer_size,
+			 (unsigned int) sub->dma_off);
+
+		len = pcm_buffer_size - sub->dma_off;
+
+		source = alsa_rt->dma_area + sub->dma_off;
+		memcpy_swahw32(urb->buffer, source, len);
+
+		source = alsa_rt->dma_area;
+		memcpy_swahw32(urb->buffer + len, source,
+			       PCM_PACKET_SIZE - len);
+	}
+	sub->dma_off += PCM_PACKET_SIZE;
+	if (sub->dma_off >= pcm_buffer_size)
+		sub->dma_off -= pcm_buffer_size;
+
+	sub->period_off += PCM_PACKET_SIZE;
+	if (sub->period_off >= alsa_rt->period_size) {
+		sub->period_off %= alsa_rt->period_size;
+		return true;
+	}
+	return false;
+}
+
+static void hiface_pcm_out_urb_handler(struct urb *usb_urb)
+{
+	struct pcm_urb *out_urb = usb_urb->context;
+	struct pcm_runtime *rt = out_urb->chip->pcm;
+	struct pcm_substream *sub;
+	bool do_period_elapsed = false;
+	unsigned long flags;
+	int ret;
+
+	if (rt->panic || rt->stream_state == STREAM_STOPPING)
+		return;
+
+	if (unlikely(usb_urb->status == -ENOENT ||	/* unlinked */
+		     usb_urb->status == -ENODEV ||	/* device removed */
+		     usb_urb->status == -ECONNRESET ||	/* unlinked */
+		     usb_urb->status == -ESHUTDOWN)) {	/* device disabled */
+		goto out_fail;
+	}
+
+	if (rt->stream_state == STREAM_STARTING) {
+		rt->stream_wait_cond = true;
+		wake_up(&rt->stream_wait_queue);
+	}
+
+	/* now send our playback data (if a free out urb was found) */
+	sub = &rt->playback;
+	spin_lock_irqsave(&sub->lock, flags);
+	if (sub->active)
+		do_period_elapsed = hiface_pcm_playback(sub, out_urb);
+	else
+		memset(out_urb->buffer, 0, PCM_PACKET_SIZE);
+
+	spin_unlock_irqrestore(&sub->lock, flags);
+
+	if (do_period_elapsed)
+		snd_pcm_period_elapsed(sub->instance);
+
+	ret = usb_submit_urb(&out_urb->instance, GFP_ATOMIC);
+	if (ret < 0)
+		goto out_fail;
+
+	return;
+
+out_fail:
+	rt->panic = true;
+}
+
+static int hiface_pcm_open(struct snd_pcm_substream *alsa_sub)
+{
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+	struct pcm_substream *sub = NULL;
+	struct snd_pcm_runtime *alsa_rt = alsa_sub->runtime;
+	int ret;
+
+	if (rt->panic)
+		return -EPIPE;
+
+	mutex_lock(&rt->stream_mutex);
+	alsa_rt->hw = pcm_hw;
+
+	if (alsa_sub->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		sub = &rt->playback;
+
+	if (!sub) {
+		struct device *device = &rt->chip->dev->dev;
+		mutex_unlock(&rt->stream_mutex);
+		dev_err(device, "Invalid stream type\n");
+		return -EINVAL;
+	}
+
+	if (rt->extra_freq) {
+		alsa_rt->hw.rates |= SNDRV_PCM_RATE_KNOT;
+		alsa_rt->hw.rate_max = 384000;
+
+		/* explicit constraints needed as we added SNDRV_PCM_RATE_KNOT */
+		ret = snd_pcm_hw_constraint_list(alsa_sub->runtime, 0,
+						 SNDRV_PCM_HW_PARAM_RATE,
+						 &constraints_extra_rates);
+		if (ret < 0) {
+			mutex_unlock(&rt->stream_mutex);
+			return ret;
+		}
+	}
+
+	sub->instance = alsa_sub;
+	sub->active = false;
+	mutex_unlock(&rt->stream_mutex);
+	return 0;
+}
+
+static int hiface_pcm_close(struct snd_pcm_substream *alsa_sub)
+{
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+	struct pcm_substream *sub = hiface_pcm_get_substream(alsa_sub);
+	unsigned long flags;
+
+	if (rt->panic)
+		return 0;
+
+	mutex_lock(&rt->stream_mutex);
+	if (sub) {
+		hiface_pcm_stream_stop(rt);
+
+		/* deactivate substream */
+		spin_lock_irqsave(&sub->lock, flags);
+		sub->instance = NULL;
+		sub->active = false;
+		spin_unlock_irqrestore(&sub->lock, flags);
+
+	}
+	mutex_unlock(&rt->stream_mutex);
+	return 0;
+}
+
+static int hiface_pcm_hw_params(struct snd_pcm_substream *alsa_sub,
+				struct snd_pcm_hw_params *hw_params)
+{
+	return snd_pcm_lib_alloc_vmalloc_buffer(alsa_sub,
+						params_buffer_bytes(hw_params));
+}
+
+static int hiface_pcm_hw_free(struct snd_pcm_substream *alsa_sub)
+{
+	return snd_pcm_lib_free_vmalloc_buffer(alsa_sub);
+}
+
+static int hiface_pcm_prepare(struct snd_pcm_substream *alsa_sub)
+{
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+	struct pcm_substream *sub = hiface_pcm_get_substream(alsa_sub);
+	struct snd_pcm_runtime *alsa_rt = alsa_sub->runtime;
+	int ret;
+
+	if (rt->panic)
+		return -EPIPE;
+	if (!sub)
+		return -ENODEV;
+
+	mutex_lock(&rt->stream_mutex);
+
+	sub->dma_off = 0;
+	sub->period_off = 0;
+
+	if (rt->stream_state == STREAM_DISABLED) {
+
+		ret = hiface_pcm_set_rate(rt, alsa_rt->rate);
+		if (ret) {
+			mutex_unlock(&rt->stream_mutex);
+			return ret;
+		}
+		ret = hiface_pcm_stream_start(rt);
+		if (ret) {
+			mutex_unlock(&rt->stream_mutex);
+			return ret;
+		}
+	}
+	mutex_unlock(&rt->stream_mutex);
+	return 0;
+}
+
+static int hiface_pcm_trigger(struct snd_pcm_substream *alsa_sub, int cmd)
+{
+	struct pcm_substream *sub = hiface_pcm_get_substream(alsa_sub);
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+
+	if (rt->panic)
+		return -EPIPE;
+	if (!sub)
+		return -ENODEV;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
+		spin_lock_irq(&sub->lock);
+		sub->active = true;
+		spin_unlock_irq(&sub->lock);
+		return 0;
+
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
+		spin_lock_irq(&sub->lock);
+		sub->active = false;
+		spin_unlock_irq(&sub->lock);
+		return 0;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static snd_pcm_uframes_t hiface_pcm_pointer(struct snd_pcm_substream *alsa_sub)
+{
+	struct pcm_substream *sub = hiface_pcm_get_substream(alsa_sub);
+	struct pcm_runtime *rt = snd_pcm_substream_chip(alsa_sub);
+	unsigned long flags;
+	snd_pcm_uframes_t dma_offset;
+
+	if (rt->panic || !sub)
+		return SNDRV_PCM_STATE_XRUN;
+
+	spin_lock_irqsave(&sub->lock, flags);
+	dma_offset = sub->dma_off;
+	spin_unlock_irqrestore(&sub->lock, flags);
+	return bytes_to_frames(alsa_sub->runtime, dma_offset);
+}
+
+static struct snd_pcm_ops pcm_ops = {
+	.open = hiface_pcm_open,
+	.close = hiface_pcm_close,
+	.ioctl = snd_pcm_lib_ioctl,
+	.hw_params = hiface_pcm_hw_params,
+	.hw_free = hiface_pcm_hw_free,
+	.prepare = hiface_pcm_prepare,
+	.trigger = hiface_pcm_trigger,
+	.pointer = hiface_pcm_pointer,
+	.page = snd_pcm_lib_get_vmalloc_page,
+	.mmap = snd_pcm_lib_mmap_vmalloc,
+};
+
+static int hiface_pcm_init_urb(struct pcm_urb *urb,
+			       struct hiface_chip *chip,
+			       unsigned int ep,
+			       void (*handler)(struct urb *))
+{
+	urb->chip = chip;
+	usb_init_urb(&urb->instance);
+
+	urb->buffer = kzalloc(PCM_PACKET_SIZE, GFP_KERNEL);
+	if (!urb->buffer)
+		return -ENOMEM;
+
+	usb_fill_bulk_urb(&urb->instance, chip->dev,
+			  usb_sndbulkpipe(chip->dev, ep), (void *)urb->buffer,
+			  PCM_PACKET_SIZE, handler, urb);
+	init_usb_anchor(&urb->submitted);
+
+	return 0;
+}
+
+void hiface_pcm_abort(struct hiface_chip *chip)
+{
+	struct pcm_runtime *rt = chip->pcm;
+
+	if (rt) {
+		rt->panic = true;
+
+		mutex_lock(&rt->stream_mutex);
+		hiface_pcm_stream_stop(rt);
+		mutex_unlock(&rt->stream_mutex);
+	}
+}
+
+static void hiface_pcm_destroy(struct hiface_chip *chip)
+{
+	struct pcm_runtime *rt = chip->pcm;
+	int i;
+
+	for (i = 0; i < PCM_N_URBS; i++)
+		kfree(rt->out_urbs[i].buffer);
+
+	kfree(chip->pcm);
+	chip->pcm = NULL;
+}
+
+static void hiface_pcm_free(struct snd_pcm *pcm)
+{
+	struct pcm_runtime *rt = pcm->private_data;
+
+	if (rt)
+		hiface_pcm_destroy(rt->chip);
+}
+
+int hiface_pcm_init(struct hiface_chip *chip, u8 extra_freq)
+{
+	int i;
+	int ret;
+	struct snd_pcm *pcm;
+	struct pcm_runtime *rt;
+
+	rt = kzalloc(sizeof(*rt), GFP_KERNEL);
+	if (!rt)
+		return -ENOMEM;
+
+	rt->chip = chip;
+	rt->stream_state = STREAM_DISABLED;
+	if (extra_freq)
+		rt->extra_freq = 1;
+
+	init_waitqueue_head(&rt->stream_wait_queue);
+	mutex_init(&rt->stream_mutex);
+	spin_lock_init(&rt->playback.lock);
+
+	for (i = 0; i < PCM_N_URBS; i++)
+		hiface_pcm_init_urb(&rt->out_urbs[i], chip, OUT_EP,
+				    hiface_pcm_out_urb_handler);
+
+	ret = snd_pcm_new(chip->card, "USB-SPDIF Audio", 0, 1, 0, &pcm);
+	if (ret < 0) {
+		kfree(rt);
+		dev_err(&chip->dev->dev, "Cannot create pcm instance\n");
+		return ret;
+	}
+
+	pcm->private_data = rt;
+	pcm->private_free = hiface_pcm_free;
+
+	strlcpy(pcm->name, "USB-SPDIF Audio", sizeof(pcm->name));
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &pcm_ops);
+
+	rt->instance = pcm;
+
+	chip->pcm = rt;
+	return 0;
+}
diff --git a/sound/usb/hiface/pcm.h b/sound/usb/hiface/pcm.h
new file mode 100644
index 0000000..77edd7c
--- /dev/null
+++ b/sound/usb/hiface/pcm.h
@@ -0,0 +1,24 @@
+/*
+ * Linux driver for M2Tech hiFace compatible devices
+ *
+ * Copyright 2012-2013 (C) M2TECH S.r.l and Amarula Solutions B.V.
+ *
+ * Authors:  Michael Trimarchi <michael@amarulasolutions.com>
+ *           Antonio Ospite <ao2@amarulasolutions.com>
+ *
+ * The driver is based on the work done in TerraTec DMX 6Fire USB
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef HIFACE_PCM_H
+#define HIFACE_PCM_H
+
+struct hiface_chip;
+
+int hiface_pcm_init(struct hiface_chip *chip, u8 extra_freq);
+void hiface_pcm_abort(struct hiface_chip *chip);
+#endif /* HIFACE_PCM_H */