[PATCH 2/2] USB: Gadget: Add Audio Class 2.0 Driver

* [PATCH 2/2] USB: Gadget: Add Audio Class 2.0 Driver
@ 2011-08-19 11:22 Jassi Brar
       [not found] ` <1313752934-20081-1-git-send-email-jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
  0 siblings, 1 reply; 17+ messages in thread
From: Jassi Brar @ 2011-08-19 11:22 UTC (permalink / raw)
  To: linux-usb-u79uwXL29TY76Z2rM5mHXA, balbi-l0cyMroinI0, gregkh-l3A5Bk7waGM
  Cc: alsa-devel-K7yf7f+aM1XWsZ/bQMPhNw, zonque-Re5JQEeQqe8AvxtiuMwx3w,
	yadi.brar01-Re5JQEeQqe8AvxtiuMwx3w, Jassi Brar

This is a flexible USB Audio Class 2.0 compliant gadget driver that
implements a simple topology with a virtual sound card exposed at
the function side.

The driver doesn't expect any real audio codec to be present on the
function - the audio streams are simply sinked to and sourced from a
virtual ALSA sound card created. The user-space application may choose
to do whatever it wants with the data received from the USB Host and
choose to provide whatever it wants as audio data to the USB Host.

Capture(USB-Out) and Playback(USB-In) can be run at independent
configurations specified via module parameters while loading the driver.

Signed-off-by: Yadi Brar <yadi.brar01-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Signed-off-by: Jassi Brar <jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---

===========
How To Test
===========
  USB_DEV$ insmod g_audio2.ko c_srate=64000 p_srate=48000 ; say
    gadget: high speed config #1: UAC2

  USB_DEV$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: uac2 [uac2], device 0: UAC2 PCM [UAC2 PCM]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

  USB_DEV$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: uac2 [uac2], device 0: UAC2 PCM [UAC2 PCM]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

  USB_HOST$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC665 Analog [ALC665 Analog]
  Subdevices: 0/1
  Subdevice #0: subdevice #0
card 1: Gadget [UAC2 Gadget], device 0: USB Audio [USB Audio]  <<<<<<
  Subdevices: 1/1
  Subdevice #0: subdevice #0

  USB_HOST$ arecord -l
**** List of CAPTURE Hardware Devices ****
card 0: PCH [HDA Intel PCH], device 0: ALC665 Analog [ALC665 Analog]
  Subdevices: 1/1
  Subdevice #0: subdevice #0
card 1: Gadget [UAC2 Gadget], device 0: USB Audio [USB Audio] <<<<<<<
  Subdevices: 1/1
  Subdevice #0: subdevice #0

 After this confirmation, you should be able to use it just like another
sound card in your system. That is, a new sound card should appear in the
sound preferences which you can select to route your default audio to and
from.

============
Test Results
============
 The driver has been tested for Half as well as Full Duplex at
Stereo, S16_LE at 44.1KHz, 48KHz and 64KHz. It should also
work for other configurations as well, except for different
sample-size(TODO).

Obviously, much depends upon the underlying UDC driver.

While testing with OMAP's implementation of Inventra HDRC, I observed
some noise for configurations for which the USB-OUT packet size chosen
by the Host is not a power of 2. USB-IN works just fine.
For ex, on both Beagle/Panda board, 48KHz USB-OUT has some noise while
64KHz is smooth. Also, with full duplex, it occasioanally shows noise.

Taking benefit of doubt, I assume this driver has unmasked some subtle
bug in the underlying UDC's ISOCH handling code ;)
Please feel free to find issue with this driver by testing it over
some other UDC.

 drivers/usb/gadget/Kconfig    |   20 +
 drivers/usb/gadget/Makefile   |    2 +
 drivers/usb/gadget/audio2.c   |  155 +++++
 drivers/usb/gadget/f_audio2.c | 1448 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 1625 insertions(+), 0 deletions(-)
 create mode 100644 drivers/usb/gadget/audio2.c
 create mode 100644 drivers/usb/gadget/f_audio2.c

diff --git a/drivers/usb/gadget/Kconfig b/drivers/usb/gadget/Kconfig
index e35dfef..95c65d8 100644
--- a/drivers/usb/gadget/Kconfig
+++ b/drivers/usb/gadget/Kconfig
@@ -599,6 +599,26 @@ config USB_ZERO_HNPTEST
 	  the "B-Peripheral" role, that device will use HNP to let this
 	  one serve as the USB host instead (in the "B-Host" role).
 
+config USB_AUDIO_2
+	tristate "Audio Gadget Class 2.0 (EXPERIMENTAL)"
+	depends on SND && EXPERIMENTAL
+	select SND_PCM
+	help
+	  This Gadget Audio driver is compatible with USB Audio Class
+	  specification 2.0. It implements 1 AudioControl interface,
+	  1 AudioStreaming Interface each for USB-OUT and USB-IN.
+	  Number of channels, sample rate and sample size can be
+	  specified as module parameters.
+	  This driver doesn't expect any real Audio codec to be present
+	  on the device - the audio streams are simply sinked to and
+	  sourced from a virtual ALSA sound card created. The user-space
+	  application may choose to do whatever it wants with the data
+	  received from the USB Host and choose to provide whatever it
+	  wants as audio data to the USB Host.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_audio2".
+
 config USB_AUDIO
 	tristate "Audio Gadget (EXPERIMENTAL)"
 	depends on SND
diff --git a/drivers/usb/gadget/Makefile b/drivers/usb/gadget/Makefile
index 7409338..fa8472e 100644
--- a/drivers/usb/gadget/Makefile
+++ b/drivers/usb/gadget/Makefile
@@ -40,6 +40,7 @@ obj-$(CONFIG_USB_COMPOSITE)	+= usb-composite.o
 #
 g_zero-y			:= zero.o
 g_audio-y			:= audio.o
+g_audio2-y			:= audio2.o
 g_ether-y			:= ether.o
 g_serial-y			:= serial.o
 g_midi-y			:= gmidi.o
@@ -57,6 +58,7 @@ g_ncm-y				:= ncm.o
 
 obj-$(CONFIG_USB_ZERO)		+= g_zero.o
 obj-$(CONFIG_USB_AUDIO)		+= g_audio.o
+obj-$(CONFIG_USB_AUDIO_2)	+= g_audio2.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o
 obj-$(CONFIG_USB_FUNCTIONFS)	+= g_ffs.o
diff --git a/drivers/usb/gadget/audio2.c b/drivers/usb/gadget/audio2.c
new file mode 100644
index 0000000..92b6d64
--- /dev/null
+++ b/drivers/usb/gadget/audio2.c
@@ -0,0 +1,155 @@
+/*
+ * audio2.c -- USB Audio Class 2.0 gadget driver
+ *
+ * Copyright (C) 2011
+ *    Yadwinder Singh (yadi.brar01-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org)
+ *    Jaswinder Singh (jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org)
+ *
+ * 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/kernel.h>
+#include <linux/utsname.h>
+#include <linux/platform_device.h>
+#include <linux/usb/composite.h>
+
+/*
+ * Kbuild is not very cooperative with respect to linking separately
+ * compiled library objects into one module.  So for now we won't use
+ * separate compilation ... ensuring init/exit sections work to shrink
+ * the runtime footprint, and giving us at least some parts of what
+ * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
+ */
+#include "f_audio2.c"
+
+enum {
+	STR_MANUFACTURER = 0,
+	STR_PRODUCT,
+	STR_CONFIG,
+};
+
+/* Thanks to Linux Foundation for donating this product ID. */
+#define UAC2_VENDOR	0x1d6b	/* Linux Foundation */
+#define UAC2_PRODUCT	0x0102	/* Linux-USB Audio Gadget */
+
+static const char manufacturer[] = "Linux Foundation";
+static const char product_desc[] = "UAC2 Gadget";
+static const char config[] = "Simple Source/Sink";
+
+static struct usb_string strings_cdev[] = {
+	[STR_MANUFACTURER].s = manufacturer,
+	[STR_PRODUCT].s = product_desc,
+	[STR_CONFIG].s = config,
+	{},
+};
+
+static struct usb_gadget_strings stringtab = {
+	.language = 0x0409,	/* en-us */
+	.strings = strings_cdev,
+};
+
+static struct usb_gadget_strings *cdev_strings[] = {
+	&stringtab,
+	NULL,
+};
+
+static struct usb_device_descriptor device_desc = {
+	.bLength = sizeof device_desc,
+	.bDescriptorType = USB_DT_DEVICE,
+
+	.bcdUSB = cpu_to_le16(0x200),
+	.bDeviceClass = USB_CLASS_MISC,
+	.bDeviceSubClass = 0x02,
+	.bDeviceProtocol = 0x01,
+	.idVendor = cpu_to_le16(UAC2_VENDOR),
+	.idProduct = cpu_to_le16(UAC2_PRODUCT),
+	/*
+	 * Implemented features of USB Audio Device class solely
+	 * depend on this driver, so this is where we decide the
+	 * version of the device.
+	 * Currently, the lowest version of simplest driver - 00.01
+	 */
+	.bcdDevice = cpu_to_le16(0x0001),
+	.bNumConfigurations = 1,
+};
+
+static struct usb_otg_descriptor otg_desc = {
+	.bLength = sizeof otg_desc,
+	.bDescriptorType = USB_DT_OTG,
+
+	.bmAttributes = USB_OTG_SRP,
+};
+
+const struct usb_descriptor_header *otgd[] = {
+	(struct usb_descriptor_header *) &otg_desc,
+	NULL,
+};
+
+static struct usb_configuration audio_config = {
+	.label = "UAC2",
+	.unbind = uac2_unbind_config,
+	.bConfigurationValue = 1,
+	.bmAttributes = USB_CONFIG_ATT_SELFPOWER,
+};
+
+static int __init
+audio_bind(struct usb_composite_dev *cdev)
+{
+	int  id;
+
+	/* Allocate string descriptor numbers */
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+
+	strings_cdev[STR_MANUFACTURER].id = id;
+	device_desc.iManufacturer = id;
+
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+
+	strings_cdev[STR_PRODUCT].id = id;
+	device_desc.iProduct = id;
+
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+
+	strings_cdev[STR_CONFIG].id = id;
+	audio_config.iConfiguration = id;
+
+	if (gadget_is_otg(cdev->gadget)) {
+		audio_config.descriptors = otgd;
+		otg_desc.bmAttributes |= USB_OTG_HNP;
+		audio_config.bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	return usb_add_config(cdev, &audio_config, uac2_bind_config);
+}
+
+static struct usb_composite_driver audio_driver = {
+	.name = "USB Audio Class 2.0",
+	.dev = &device_desc,
+	.strings = cdev_strings,
+	.max_speed = USB_SPEED_HIGH,
+};
+
+static int __init init(void)
+{
+	return usb_composite_probe(&audio_driver, audio_bind);
+}
+module_init(init);
+
+static void __exit cleanup(void)
+{
+	usb_composite_unregister(&audio_driver);
+}
+module_exit(cleanup);
+
+MODULE_DESCRIPTION("USB Audio Class 2.0 Gadget Driver");
+MODULE_AUTHOR("Yadi Brar, Jassi Brar");
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/gadget/f_audio2.c b/drivers/usb/gadget/f_audio2.c
new file mode 100644
index 0000000..261d587
--- /dev/null
+++ b/drivers/usb/gadget/f_audio2.c
@@ -0,0 +1,1448 @@
+/*
+ * f_audio2.c -- USB Audio Class 2.0 Function
+ *
+ * Copyright (C) 2011
+ *    Yadwinder Singh (yadi.brar01-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org)
+ *    Jaswinder Singh (jassisinghbrar-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org)
+ *
+ * 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/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+/* Playback(USB-IN) Default Stereo - Fl/Fr */
+static int p_chmask = 0x3;
+module_param(p_chmask, uint, S_IRUGO);
+MODULE_PARM_DESC(p_chmask, "Playback Channel Mask");
+
+/* Playback Default 48 KHz */
+static int p_srate = 48000;
+module_param(p_srate, uint, S_IRUGO);
+MODULE_PARM_DESC(p_srate, "Playback Sampling Rate");
+
+/* Playback Default 16bits/sample */
+static int p_ssize = 2;
+module_param(p_ssize, uint, S_IRUGO);
+MODULE_PARM_DESC(p_ssize, "Playback Sample Size(bytes)");
+
+/* Capture(USB-OUT) Default Stereo - Fl/Fr */
+static int c_chmask = 0x3;
+module_param(c_chmask, uint, S_IRUGO);
+MODULE_PARM_DESC(c_chmask, "Capture Channel Mask");
+
+/* Capture Default 48 KHz */
+static int c_srate = 48000;
+module_param(c_srate, uint, S_IRUGO);
+MODULE_PARM_DESC(c_srate, "Capture Sampling Rate");
+
+/* Capture Default 16bits/sample */
+static int c_ssize = 2;
+module_param(c_ssize, uint, S_IRUGO);
+MODULE_PARM_DESC(c_ssize, "Capture Sample Size(bytes)");
+
+#define DMA_ADDR_INVALID	(~(dma_addr_t)0)
+
+#define ALT_SET(x, a)	do {(x) &= ~0xff; (x) |= (a); } while (0)
+#define ALT_GET(x)	((x) & 0xff)
+#define INTF_SET(x, i)	do {(x) &= 0xff; (x) |= ((i) << 8); } while (0)
+#define INTF_GET(x)	((x >> 8) & 0xff)
+
+/* Keep everyone on toes */
+#define USB_XFERS	2
+
+/*
+ * The driver implements a simple UAC_2 topology.
+ * USB-OUT -> IT_1 -> OT_3 -> ALSA_Capture
+ * ALSA_Playback -> IT_2 -> OT_4 -> USB-IN
+ * Capture and Playback sampling rates are independently
+ *  controlled by two clock sources :
+ *    CLK_5 := c_srate, and CLK_6 := p_srate
+ */
+#define USB_OUT_IT_ID	1
+#define IO_IN_IT_ID	2
+#define IO_OUT_OT_ID	3
+#define USB_IN_OT_ID	4
+#define USB_OUT_CLK_ID	5
+#define USB_IN_CLK_ID	6
+
+#define CONTROL_ABSENT	0
+#define CONTROL_RDONLY	1
+#define CONTROL_RDWR	3
+
+#define CLK_FREQ_CTRL	0
+#define CLK_VLD_CTRL	2
+
+#define COPY_CTRL	0
+#define CONN_CTRL	2
+#define OVRLD_CTRL	4
+#define CLSTR_CTRL	6
+#define UNFLW_CTRL	8
+#define OVFLW_CTRL	10
+
+const char *uac2_name = "snd_uac2";
+
+struct uac2_req {
+	struct uac2_rtd_params *pp; /* parent param */
+	struct usb_request *req;
+};
+
+struct uac2_rtd_params {
+	bool ep_enabled; /* if the ep is enabled */
+	/* Size of the ring buffer */
+	size_t dma_bytes;
+	unsigned char *dma_area;
+
+	struct snd_pcm_substream *ss;
+
+	/* Ring buffer */
+	ssize_t hw_ptr;
+
+	void *rbuf;
+
+	size_t period_size;
+
+	unsigned max_psize;
+	struct uac2_req ureq[USB_XFERS];
+
+	spinlock_t lock;
+};
+
+struct snd_uac2_chip {
+	struct platform_device pdev;
+	struct platform_driver pdrv;
+
+	struct uac2_rtd_params p_prm;
+	struct uac2_rtd_params c_prm;
+
+	struct snd_card *card;
+	struct snd_pcm *pcm;
+};
+
+#define BUFF_SIZE_MAX	(PAGE_SIZE * 16)
+#define PRD_SIZE_MAX	PAGE_SIZE
+#define MIN_PERIODS	4
+
+static struct snd_pcm_hardware uac2_pcm_hardware = {
+	.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER
+		 | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID
+		 | SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME,
+	.rates = SNDRV_PCM_RATE_CONTINUOUS,
+	.periods_max = BUFF_SIZE_MAX / PRD_SIZE_MAX,
+	.buffer_bytes_max = BUFF_SIZE_MAX,
+	.period_bytes_max = PRD_SIZE_MAX,
+	.periods_min = MIN_PERIODS,
+};
+
+struct audio_dev {
+	/* Currently active {Interface[15:8] | AltSettings[7:0]} */
+	__u16 ac_alt, as_out_alt, as_in_alt;
+
+	struct usb_ep *in_ep, *out_ep;
+	struct usb_function func;
+
+	/* The ALSA Sound Card it represents on the USB-Client side */
+	struct snd_uac2_chip uac2;
+};
+
+static struct audio_dev *agdev_g;
+
+static inline
+struct audio_dev *func_to_agdev(struct usb_function *f)
+{
+	return container_of(f, struct audio_dev, func);
+}
+
+static inline
+struct audio_dev *uac2_to_agdev(struct snd_uac2_chip *u)
+{
+	return container_of(u, struct audio_dev, uac2);
+}
+
+static inline
+struct snd_uac2_chip *pdev_to_uac2(struct platform_device *p)
+{
+	return container_of(p, struct snd_uac2_chip, pdev);
+}
+
+static inline
+struct snd_uac2_chip *prm_to_uac2(struct uac2_rtd_params *r)
+{
+	struct snd_uac2_chip *uac2 = container_of(r,
+					struct snd_uac2_chip, c_prm);
+
+	if (&uac2->c_prm != r)
+		uac2 = container_of(r, struct snd_uac2_chip, p_prm);
+
+	return uac2;
+}
+
+static inline
+uint num_channels(uint chanmask)
+{
+	uint num = 0;
+
+	while (chanmask) {
+		num += (chanmask & 1);
+		chanmask >>= 1;
+	}
+
+	return num;
+}
+
+static void
+agdev_iso_complete(struct usb_ep *ep, struct usb_request *req)
+{
+	unsigned pending;
+	unsigned long flags;
+	bool update_alsa = false;
+	unsigned char *src, *dst;
+	int status = req->status;
+	struct uac2_req *ur = req->context;
+	struct snd_pcm_substream *substream;
+	struct uac2_rtd_params *prm = ur->pp;
+	struct snd_uac2_chip *uac2 = prm_to_uac2(prm);
+
+	/* i/f shutting down */
+	if (!prm->ep_enabled)
+		return;
+
+	/*
+	 * We can't really do much about bad xfers.
+	 * Afterall, the ISOCH xfers could fail legitimately.
+	 */
+	if (status)
+		pr_debug("%s: iso_complete status(%d) %d/%d\n",
+			__func__, status, req->actual, req->length);
+
+	substream = prm->ss;
+
+	/* Do nothing if ALSA isn't active */
+	if (!substream)
+		goto exit;
+
+	spin_lock_irqsave(&prm->lock, flags);
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		src = prm->dma_area + prm->hw_ptr;
+		req->actual = req->length;
+		dst = req->buf;
+	} else {
+		dst = prm->dma_area + prm->hw_ptr;
+		src = req->buf;
+	}
+
+	pending = prm->hw_ptr % prm->period_size;
+	pending += req->actual;
+	if (pending >= prm->period_size)
+		update_alsa = true;
+
+	prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
+
+	spin_unlock_irqrestore(&prm->lock, flags);
+
+	/* Pack USB load in ALSA ring buffer */
+	memcpy(dst, src, req->actual);
+exit:
+	if (usb_ep_queue(ep, req, GFP_ATOMIC))
+		dev_err(&uac2->pdev.dev, "%d Error!\n", __LINE__);
+
+	if (update_alsa)
+		snd_pcm_period_elapsed(substream);
+
+	return;
+}
+
+static int
+uac2_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
+	struct audio_dev *agdev = uac2_to_agdev(uac2);
+	struct uac2_rtd_params *prm;
+	unsigned long flags;
+	struct usb_ep *ep;
+	int err = 0;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		ep = agdev->in_ep;
+		prm = &uac2->p_prm;
+	} else {
+		ep = agdev->out_ep;
+		prm = &uac2->c_prm;
+	}
+
+	spin_lock_irqsave(&prm->lock, flags);
+
+	/* Reset */
+	prm->hw_ptr = 0;
+
+	switch (cmd) {
+	case SNDRV_PCM_TRIGGER_START:
+	case SNDRV_PCM_TRIGGER_RESUME:
+		prm->ss = substream;
+		break;
+	case SNDRV_PCM_TRIGGER_STOP:
+	case SNDRV_PCM_TRIGGER_SUSPEND:
+		prm->ss = NULL;
+		break;
+	default:
+		err = -EINVAL;
+	}
+
+	spin_unlock_irqrestore(&prm->lock, flags);
+
+	/* Clear buffer after Play stops */
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && !prm->ss)
+		memset(prm->rbuf, 0, prm->max_psize * USB_XFERS);
+
+	return err;
+}
+
+static snd_pcm_uframes_t uac2_pcm_pointer(struct snd_pcm_substream *substream)
+{
+	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
+	struct uac2_rtd_params *prm;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		prm = &uac2->p_prm;
+	else
+		prm = &uac2->c_prm;
+
+	return bytes_to_frames(substream->runtime, prm->hw_ptr);
+}
+
+static int uac2_pcm_hw_params(struct snd_pcm_substream *substream,
+			       struct snd_pcm_hw_params *hw_params)
+{
+	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
+	struct uac2_rtd_params *prm;
+	int err;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		prm = &uac2->p_prm;
+	else
+		prm = &uac2->c_prm;
+
+	err = snd_pcm_lib_malloc_pages(substream,
+					params_buffer_bytes(hw_params));
+	if (err >= 0) {
+		prm->dma_bytes = substream->runtime->dma_bytes;
+		prm->dma_area = substream->runtime->dma_area;
+		prm->period_size = params_period_bytes(hw_params);
+	}
+
+	return err;
+}
+
+static int uac2_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
+	struct uac2_rtd_params *prm;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		prm = &uac2->p_prm;
+	else
+		prm = &uac2->c_prm;
+
+	prm->dma_area = NULL;
+	prm->dma_bytes = 0;
+	prm->period_size = 0;
+
+	return snd_pcm_lib_free_pages(substream);
+}
+
+static int uac2_pcm_open(struct snd_pcm_substream *substream)
+{
+	struct snd_uac2_chip *uac2 = snd_pcm_substream_chip(substream);
+	struct snd_pcm_runtime *runtime = substream->runtime;
+
+	runtime->hw = uac2_pcm_hardware;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+		spin_lock_init(&uac2->p_prm.lock);
+		runtime->hw.rate_min = p_srate;
+		runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE; /* ! p_ssize ! */
+		runtime->hw.channels_min = num_channels(p_chmask);
+		runtime->hw.period_bytes_min = 2 * uac2->p_prm.max_psize
+						/ runtime->hw.periods_min;
+	} else {
+		spin_lock_init(&uac2->c_prm.lock);
+		runtime->hw.rate_min = c_srate;
+		runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE; /* ! c_ssize ! */
+		runtime->hw.channels_min = num_channels(c_chmask);
+		runtime->hw.period_bytes_min = 2 * uac2->c_prm.max_psize
+						/ runtime->hw.periods_min;
+	}
+
+	runtime->hw.rate_max = runtime->hw.rate_min;
+	runtime->hw.channels_max = runtime->hw.channels_min;
+
+	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);
+
+	return 0;
+}
+
+/* ALSA cries without these function pointers */
+static int uac2_pcm_null(struct snd_pcm_substream *substream)
+{
+	return 0;
+}
+
+static struct snd_pcm_ops uac2_pcm_ops = {
+	.open = uac2_pcm_open,
+	.close = uac2_pcm_null,
+	.ioctl = snd_pcm_lib_ioctl,
+	.hw_params = uac2_pcm_hw_params,
+	.hw_free = uac2_pcm_hw_free,
+	.trigger = uac2_pcm_trigger,
+	.pointer = uac2_pcm_pointer,
+	.prepare = uac2_pcm_null,
+};
+
+static int __devinit snd_uac2_probe(struct platform_device *pdev)
+{
+	struct snd_uac2_chip *uac2 = pdev_to_uac2(pdev);
+	struct snd_card *card;
+	struct snd_pcm *pcm;
+	int err;
+
+	/* Choose any slot, with no id */
+	err = snd_card_create(-1, NULL, THIS_MODULE, 0, &card);
+	if (err < 0)
+		return err;
+
+	uac2->card = card;
+
+	/*
+	 * Create first PCM device
+	 * Create a substream only for non-zero channel streams
+	 */
+	err = snd_pcm_new(uac2->card, "UAC2 PCM", 0,
+			       p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);
+	if (err < 0)
+		goto snd_fail;
+
+	strcpy(pcm->name, "UAC2 PCM");
+	pcm->private_data = uac2;
+
+	uac2->pcm = pcm;
+
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac2_pcm_ops);
+	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac2_pcm_ops);
+
+	strcpy(card->driver, "uac2");
+	strcpy(card->shortname, "uac2");
+	sprintf(card->longname, "uac2 %i", pdev->id);
+
+	snd_card_set_dev(card, &pdev->dev);
+
+	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,
+		snd_dma_continuous_data(GFP_KERNEL), 0, BUFF_SIZE_MAX);
+
+	err = snd_card_register(card);
+	if (!err) {
+		platform_set_drvdata(pdev, card);
+		return 0;
+	}
+
+snd_fail:
+	snd_card_free(card);
+
+	uac2->pcm = NULL;
+	uac2->card = NULL;
+
+	return err;
+}
+
+static int __devexit snd_uac2_remove(struct platform_device *pdev)
+{
+	struct snd_card *card = platform_get_drvdata(pdev);
+
+	platform_set_drvdata(pdev, NULL);
+
+	if (card)
+		return snd_card_free(card);
+
+	return 0;
+}
+
+static int alsa_uac2_init(struct audio_dev *agdev)
+{
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	int err;
+
+	uac2->pdrv.probe = snd_uac2_probe;
+	uac2->pdrv.remove = snd_uac2_remove;
+	uac2->pdrv.driver.name = uac2_name;
+
+	uac2->pdev.id = 0;
+	uac2->pdev.name = uac2_name;
+
+	/* Register snd_uac2 driver */
+	err = platform_driver_register(&uac2->pdrv);
+	if (err)
+		return err;
+
+	/* Register snd_uac2 device */
+	err = platform_device_register(&uac2->pdev);
+	if (err)
+		platform_driver_unregister(&uac2->pdrv);
+
+	return err;
+}
+
+static void alsa_uac2_exit(struct audio_dev *agdev)
+{
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+
+	platform_driver_unregister(&uac2->pdrv);
+	platform_device_unregister(&uac2->pdev);
+}
+
+
+/* --------- USB Function Interface ------------- */
+
+enum {
+	STR_ASSOC,
+	STR_IF_CTRL,
+	STR_CLKSRC_IN,
+	STR_CLKSRC_OUT,
+	STR_USB_IT,
+	STR_IO_IT,
+	STR_USB_OT,
+	STR_IO_OT,
+	STR_AS_OUT_ALT0,
+	STR_AS_OUT_ALT1,
+	STR_AS_IN_ALT0,
+	STR_AS_IN_ALT1,
+};
+
+static const char ifassoc[] = "Source/Sink";
+static const char ifctrl[] = "Topology Control";
+static char clksrc_in[8];
+static char clksrc_out[8];
+static const char usb_it[] = "USBH Out";
+static const char io_it[] = "USBD Out";
+static const char usb_ot[] = "USBH In";
+static const char io_ot[] = "USBD In";
+static const char out_alt0[] = "Playback Inactive";
+static const char out_alt1[] = "Playback Active";
+static const char in_alt0[] = "Capture Inactive";
+static const char in_alt1[] = "Capture Active";
+
+static struct usb_string strings_fn[] = {
+	[STR_ASSOC].s = ifassoc,
+	[STR_IF_CTRL].s = ifctrl,
+	[STR_CLKSRC_IN].s = clksrc_in,
+	[STR_CLKSRC_OUT].s = clksrc_out,
+	[STR_USB_IT].s = usb_it,
+	[STR_IO_IT].s = io_it,
+	[STR_USB_OT].s = usb_ot,
+	[STR_IO_OT].s = io_ot,
+	[STR_AS_OUT_ALT0].s = out_alt0,
+	[STR_AS_OUT_ALT1].s = out_alt1,
+	[STR_AS_IN_ALT0].s = in_alt0,
+	[STR_AS_IN_ALT1].s = in_alt1,
+	{ },
+};
+
+static struct usb_gadget_strings str_fn = {
+	.language = 0x0409,	/* en-us */
+	.strings = strings_fn,
+};
+
+static struct usb_gadget_strings *fn_strings[] = {
+	&str_fn,
+	NULL,
+};
+
+static struct usb_qualifier_descriptor devqual_desc = {
+	.bLength = sizeof devqual_desc,
+	.bDescriptorType = USB_DT_DEVICE_QUALIFIER,
+
+	.bcdUSB = cpu_to_le16(0x200),
+	.bDeviceClass = USB_CLASS_MISC,
+	.bDeviceSubClass = 0x02,
+	.bDeviceProtocol = 0x01,
+	.bNumConfigurations = 1,
+	.bRESERVED = 0,
+};
+
+static struct usb_interface_assoc_descriptor iad_desc = {
+	.bLength = sizeof iad_desc,
+	.bDescriptorType = USB_DT_INTERFACE_ASSOCIATION,
+
+	.bFirstInterface = 0,
+	.bInterfaceCount = 3,
+	.bFunctionClass = USB_CLASS_AUDIO,
+	.bFunctionSubClass = UAC2_FUNCTION_SUBCLASS_UNDEFINED,
+	.bFunctionProtocol = UAC_VERSION_2,
+};
+
+/* Audio Control Interface */
+static struct usb_interface_descriptor std_ac_if_desc = {
+	.bLength = sizeof std_ac_if_desc,
+	.bDescriptorType = USB_DT_INTERFACE,
+
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 0,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL,
+	.bInterfaceProtocol = UAC_VERSION_2,
+};
+
+/* Clock source for IN traffic */
+struct uac_clock_source_descriptor in_clk_src_desc = {
+	.bLength = sizeof in_clk_src_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC2_CLOCK_SOURCE,
+	.bClockID = USB_IN_CLK_ID,
+	.bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
+	.bmControls = (CONTROL_RDONLY << CLK_FREQ_CTRL),
+	.bAssocTerminal = 0,
+};
+
+/* Clock source for OUT traffic */
+struct uac_clock_source_descriptor out_clk_src_desc = {
+	.bLength = sizeof out_clk_src_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC2_CLOCK_SOURCE,
+	.bClockID = USB_OUT_CLK_ID,
+	.bmAttributes = UAC_CLOCK_SOURCE_TYPE_INT_FIXED,
+	.bmControls = (CONTROL_RDONLY << CLK_FREQ_CTRL),
+	.bAssocTerminal = 0,
+};
+
+/* Input Terminal for USB_OUT */
+struct uac2_input_terminal_descriptor usb_out_it_desc = {
+	.bLength = sizeof usb_out_it_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_INPUT_TERMINAL,
+	.bTerminalID = USB_OUT_IT_ID,
+	.wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
+	.bAssocTerminal = 0,
+	.bCSourceID = USB_OUT_CLK_ID,
+	.iChannelNames = 0,
+	.bmControls = (CONTROL_RDWR << COPY_CTRL),
+};
+
+/* Input Terminal for I/O-In */
+struct uac2_input_terminal_descriptor io_in_it_desc = {
+	.bLength = sizeof io_in_it_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_INPUT_TERMINAL,
+	.bTerminalID = IO_IN_IT_ID,
+	.wTerminalType = cpu_to_le16(UAC_INPUT_TERMINAL_UNDEFINED),
+	.bAssocTerminal = 0,
+	.bCSourceID = USB_IN_CLK_ID,
+	.iChannelNames = 0,
+	.bmControls = (CONTROL_RDWR << COPY_CTRL),
+};
+
+/* Ouput Terminal for USB_IN */
+struct uac2_output_terminal_descriptor usb_in_ot_desc = {
+	.bLength = sizeof usb_in_ot_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
+	.bTerminalID = USB_IN_OT_ID,
+	.wTerminalType = cpu_to_le16(UAC_TERMINAL_STREAMING),
+	.bAssocTerminal = 0,
+	.bSourceID = IO_IN_IT_ID,
+	.bCSourceID = USB_IN_CLK_ID,
+	.bmControls = (CONTROL_RDWR << COPY_CTRL),
+};
+
+/* Ouput Terminal for I/O-Out */
+struct uac2_output_terminal_descriptor io_out_ot_desc = {
+	.bLength = sizeof io_out_ot_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_OUTPUT_TERMINAL,
+	.bTerminalID = IO_OUT_OT_ID,
+	.wTerminalType = cpu_to_le16(UAC_OUTPUT_TERMINAL_UNDEFINED),
+	.bAssocTerminal = 0,
+	.bSourceID = USB_OUT_IT_ID,
+	.bCSourceID = USB_OUT_CLK_ID,
+	.bmControls = (CONTROL_RDWR << COPY_CTRL),
+};
+
+struct uac2_ac_header_descriptor ac_hdr_desc = {
+	.bLength = sizeof ac_hdr_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_MS_HEADER,
+	.bcdADC = cpu_to_le16(0x200),
+	.bCategory = UAC2_FUNCTION_IO_BOX,
+	.wTotalLength = sizeof in_clk_src_desc + sizeof out_clk_src_desc
+			 + sizeof usb_out_it_desc + sizeof io_in_it_desc
+			+ sizeof usb_in_ot_desc + sizeof io_out_ot_desc,
+	.bmControls = 0,
+};
+
+/* Audio Streaming OUT Interface - Alt0 */
+static struct usb_interface_descriptor std_as_out_if0_desc = {
+	.bLength = sizeof std_as_out_if0_desc,
+	.bDescriptorType = USB_DT_INTERFACE,
+
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 0,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+	.bInterfaceProtocol = UAC_VERSION_2,
+};
+
+/* Audio Streaming OUT Interface - Alt1 */
+static struct usb_interface_descriptor std_as_out_if1_desc = {
+	.bLength = sizeof std_as_out_if1_desc,
+	.bDescriptorType = USB_DT_INTERFACE,
+
+	.bAlternateSetting = 1,
+	.bNumEndpoints = 1,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+	.bInterfaceProtocol = UAC_VERSION_2,
+};
+
+/* Audio Stream OUT Intface Desc */
+struct uac2_as_header_descriptor as_out_hdr_desc = {
+	.bLength = sizeof as_out_hdr_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_AS_GENERAL,
+	.bTerminalLink = USB_OUT_IT_ID,
+	.bmControls = 0,
+	.bFormatType = UAC_FORMAT_TYPE_I,
+	.bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
+	.iChannelNames = 0,
+};
+
+/* Audio USB_OUT Format */
+struct uac2_format_type_i_descriptor as_out_fmt1_desc = {
+	.bLength = sizeof as_out_fmt1_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype = UAC_FORMAT_TYPE,
+	.bFormatType = UAC_FORMAT_TYPE_I,
+};
+
+/* STD AS ISO OUT Endpoint */
+struct usb_endpoint_descriptor fs_epout_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+
+	.bEndpointAddress = USB_DIR_OUT,
+	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+	.bInterval = 1,
+};
+
+struct usb_endpoint_descriptor hs_epout_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+
+	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+	.bInterval = 4,
+};
+
+/* CS AS ISO OUT Endpoint */
+static struct uac2_iso_endpoint_descriptor as_iso_out_desc = {
+	.bLength = sizeof as_iso_out_desc,
+	.bDescriptorType = USB_DT_CS_ENDPOINT,
+
+	.bDescriptorSubtype = UAC_EP_GENERAL,
+	.bmAttributes = 0,
+	.bmControls = 0,
+	.bLockDelayUnits = 0,
+	.wLockDelay = 0,
+};
+
+/* Audio Streaming IN Interface - Alt0 */
+static struct usb_interface_descriptor std_as_in_if0_desc = {
+	.bLength = sizeof std_as_in_if0_desc,
+	.bDescriptorType = USB_DT_INTERFACE,
+
+	.bAlternateSetting = 0,
+	.bNumEndpoints = 0,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+	.bInterfaceProtocol = UAC_VERSION_2,
+};
+
+/* Audio Streaming IN Interface - Alt1 */
+static struct usb_interface_descriptor std_as_in_if1_desc = {
+	.bLength = sizeof std_as_in_if1_desc,
+	.bDescriptorType = USB_DT_INTERFACE,
+
+	.bAlternateSetting = 1,
+	.bNumEndpoints = 1,
+	.bInterfaceClass = USB_CLASS_AUDIO,
+	.bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING,
+	.bInterfaceProtocol = UAC_VERSION_2,
+};
+
+/* Audio Stream IN Intface Desc */
+struct uac2_as_header_descriptor as_in_hdr_desc = {
+	.bLength = sizeof as_in_hdr_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+
+	.bDescriptorSubtype = UAC_AS_GENERAL,
+	.bTerminalLink = USB_IN_OT_ID,
+	.bmControls = 0,
+	.bFormatType = UAC_FORMAT_TYPE_I,
+	.bmFormats = cpu_to_le32(UAC_FORMAT_TYPE_I_PCM),
+	.iChannelNames = 0,
+};
+
+/* Audio USB_IN Format */
+struct uac2_format_type_i_descriptor as_in_fmt1_desc = {
+	.bLength = sizeof as_in_fmt1_desc,
+	.bDescriptorType = USB_DT_CS_INTERFACE,
+	.bDescriptorSubtype = UAC_FORMAT_TYPE,
+	.bFormatType = UAC_FORMAT_TYPE_I,
+};
+
+/* STD AS ISO IN Endpoint */
+struct usb_endpoint_descriptor fs_epin_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+
+	.bEndpointAddress = USB_DIR_IN,
+	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+	.bInterval = 1,
+};
+
+struct usb_endpoint_descriptor hs_epin_desc = {
+	.bLength = USB_DT_ENDPOINT_SIZE,
+	.bDescriptorType = USB_DT_ENDPOINT,
+
+	.bmAttributes = USB_ENDPOINT_XFER_ISOC | USB_ENDPOINT_SYNC_ASYNC,
+	.bInterval = 4,
+};
+
+/* CS AS ISO IN Endpoint */
+static struct uac2_iso_endpoint_descriptor as_iso_in_desc = {
+	.bLength = sizeof as_iso_in_desc,
+	.bDescriptorType = USB_DT_CS_ENDPOINT,
+
+	.bDescriptorSubtype = UAC_EP_GENERAL,
+	.bmAttributes = 0,
+	.bmControls = 0,
+	.bLockDelayUnits = 0,
+	.wLockDelay = 0,
+};
+
+static struct usb_descriptor_header *fs_audio_desc[] = {
+	(struct usb_descriptor_header *)&iad_desc,
+	(struct usb_descriptor_header *)&std_ac_if_desc,
+
+	(struct usb_descriptor_header *)&ac_hdr_desc,
+	(struct usb_descriptor_header *)&in_clk_src_desc,
+	(struct usb_descriptor_header *)&out_clk_src_desc,
+	(struct usb_descriptor_header *)&usb_out_it_desc,
+	(struct usb_descriptor_header *)&io_in_it_desc,
+	(struct usb_descriptor_header *)&usb_in_ot_desc,
+	(struct usb_descriptor_header *)&io_out_ot_desc,
+
+	(struct usb_descriptor_header *)&std_as_out_if0_desc,
+	(struct usb_descriptor_header *)&std_as_out_if1_desc,
+
+	(struct usb_descriptor_header *)&as_out_hdr_desc,
+	(struct usb_descriptor_header *)&as_out_fmt1_desc,
+	(struct usb_descriptor_header *)&fs_epout_desc,
+	(struct usb_descriptor_header *)&as_iso_out_desc,
+
+	(struct usb_descriptor_header *)&std_as_in_if0_desc,
+	(struct usb_descriptor_header *)&std_as_in_if1_desc,
+
+	(struct usb_descriptor_header *)&as_in_hdr_desc,
+	(struct usb_descriptor_header *)&as_in_fmt1_desc,
+	(struct usb_descriptor_header *)&fs_epin_desc,
+	(struct usb_descriptor_header *)&as_iso_in_desc,
+	NULL,
+};
+
+static struct usb_descriptor_header *hs_audio_desc[] = {
+	(struct usb_descriptor_header *)&iad_desc,
+	(struct usb_descriptor_header *)&std_ac_if_desc,
+
+	(struct usb_descriptor_header *)&ac_hdr_desc,
+	(struct usb_descriptor_header *)&in_clk_src_desc,
+	(struct usb_descriptor_header *)&out_clk_src_desc,
+	(struct usb_descriptor_header *)&usb_out_it_desc,
+	(struct usb_descriptor_header *)&io_in_it_desc,
+	(struct usb_descriptor_header *)&usb_in_ot_desc,
+	(struct usb_descriptor_header *)&io_out_ot_desc,
+
+	(struct usb_descriptor_header *)&std_as_out_if0_desc,
+	(struct usb_descriptor_header *)&std_as_out_if1_desc,
+
+	(struct usb_descriptor_header *)&as_out_hdr_desc,
+	(struct usb_descriptor_header *)&as_out_fmt1_desc,
+	(struct usb_descriptor_header *)&hs_epout_desc,
+	(struct usb_descriptor_header *)&as_iso_out_desc,
+
+	(struct usb_descriptor_header *)&std_as_in_if0_desc,
+	(struct usb_descriptor_header *)&std_as_in_if1_desc,
+
+	(struct usb_descriptor_header *)&as_in_hdr_desc,
+	(struct usb_descriptor_header *)&as_in_fmt1_desc,
+	(struct usb_descriptor_header *)&hs_epin_desc,
+	(struct usb_descriptor_header *)&as_iso_in_desc,
+	NULL,
+};
+
+struct cntrl_cur_lay3 {
+	__u32	dCUR;
+};
+
+struct cntrl_range_lay3 {
+	__u16	wNumSubRanges;
+	__u32	dMIN;
+	__u32	dMAX;
+	__u32	dRES;
+} __packed;
+
+static inline void
+free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
+{
+	struct snd_uac2_chip *uac2 = prm_to_uac2(prm);
+	int i;
+
+	prm->ep_enabled = false;
+
+	for (i = 0; i < USB_XFERS; i++) {
+		if (prm->ureq[i].req) {
+			usb_ep_dequeue(ep, prm->ureq[i].req);
+			usb_ep_free_request(ep, prm->ureq[i].req);
+			prm->ureq[i].req = NULL;
+		}
+	}
+
+	if (usb_ep_disable(ep))
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+}
+
+static int __init
+afunc_bind(struct usb_configuration *cfg, struct usb_function *fn)
+{
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	struct usb_composite_dev *cdev = cfg->cdev;
+	struct usb_gadget *gadget = cdev->gadget;
+	struct uac2_rtd_params *prm;
+	int ret;
+
+	ret = usb_interface_id(cfg, fn);
+	if (ret < 0) {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+	std_ac_if_desc.bInterfaceNumber = ret;
+	ALT_SET(agdev->ac_alt, 0);
+	INTF_SET(agdev->ac_alt, ret);
+
+	ret = usb_interface_id(cfg, fn);
+	if (ret < 0) {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+	std_as_out_if0_desc.bInterfaceNumber = ret;
+	std_as_out_if1_desc.bInterfaceNumber = ret;
+	ALT_SET(agdev->as_out_alt, 0);
+	INTF_SET(agdev->as_out_alt, ret);
+
+	ret = usb_interface_id(cfg, fn);
+	if (ret < 0) {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return ret;
+	}
+	std_as_in_if0_desc.bInterfaceNumber = ret;
+	std_as_in_if1_desc.bInterfaceNumber = ret;
+	ALT_SET(agdev->as_in_alt, 0);
+	INTF_SET(agdev->as_in_alt, ret);
+
+	agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
+	if (!agdev->out_ep)
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+	agdev->out_ep->driver_data = agdev;
+
+	agdev->in_ep = usb_ep_autoconfig(gadget, &fs_epin_desc);
+	if (!agdev->in_ep)
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+	agdev->in_ep->driver_data = agdev;
+
+	hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
+	hs_epout_desc.wMaxPacketSize = fs_epout_desc.wMaxPacketSize;
+	hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
+	hs_epin_desc.wMaxPacketSize = fs_epin_desc.wMaxPacketSize;
+
+	fn->descriptors = usb_copy_descriptors(fs_audio_desc);
+	if (gadget_is_dualspeed(gadget))
+		fn->hs_descriptors = usb_copy_descriptors(hs_audio_desc);
+
+	prm = &agdev->uac2.c_prm;
+	prm->max_psize = hs_epout_desc.wMaxPacketSize;
+	prm->rbuf = kzalloc(prm->max_psize * USB_XFERS, GFP_KERNEL);
+	if (!prm->rbuf) {
+		prm->max_psize = 0;
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+	}
+
+	prm = &agdev->uac2.p_prm;
+	prm->max_psize = hs_epin_desc.wMaxPacketSize;
+	prm->rbuf = kzalloc(prm->max_psize * USB_XFERS, GFP_KERNEL);
+	if (!prm->rbuf) {
+		prm->max_psize = 0;
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+	}
+
+	return alsa_uac2_init(agdev);
+}
+
+static void
+afunc_unbind(struct usb_configuration *cfg, struct usb_function *fn)
+{
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct usb_composite_dev *cdev = cfg->cdev;
+	struct usb_gadget *gadget = cdev->gadget;
+	struct uac2_rtd_params *prm;
+
+	alsa_uac2_exit(agdev);
+
+	prm = &agdev->uac2.p_prm;
+	kfree(prm->rbuf);
+
+	prm = &agdev->uac2.c_prm;
+	kfree(prm->rbuf);
+
+	if (gadget_is_dualspeed(gadget))
+		usb_free_descriptors(fn->hs_descriptors);
+	usb_free_descriptors(fn->descriptors);
+
+	if (agdev->in_ep)
+		agdev->in_ep->driver_data = NULL;
+	if (agdev->out_ep)
+		agdev->out_ep->driver_data = NULL;
+}
+
+static int
+afunc_set_alt(struct usb_function *fn, unsigned intf, unsigned alt)
+{
+	struct usb_composite_dev *cdev = fn->config->cdev;
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	struct usb_gadget *gadget = cdev->gadget;
+	struct usb_request *req;
+	struct usb_ep *ep;
+	struct uac2_rtd_params *prm;
+	int i;
+
+	/* No i/f has more than 2 alt settings */
+	if (alt > 1) {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	if (intf == INTF_GET(agdev->ac_alt)) {
+		/* Control I/f has only 1 AltSetting - 0 */
+		if (alt) {
+			dev_err(&uac2->pdev.dev,
+				"%s:%d Error!\n", __func__, __LINE__);
+			return -EINVAL;
+		}
+		return 0;
+	}
+
+	if (intf == INTF_GET(agdev->as_out_alt)) {
+		ep = agdev->out_ep;
+		prm = &uac2->c_prm;
+		config_ep_by_speed(gadget, fn, ep);
+		ALT_SET(agdev->as_out_alt, alt);
+	} else if (intf == INTF_GET(agdev->as_in_alt)) {
+		ep = agdev->in_ep;
+		prm = &uac2->p_prm;
+		config_ep_by_speed(gadget, fn, ep);
+		ALT_SET(agdev->as_in_alt, alt);
+	} else {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return -EINVAL;
+	}
+
+	if (alt == 0) {
+		free_ep(prm, ep);
+		return 0;
+	}
+
+	prm->ep_enabled = true;
+	usb_ep_enable(ep);
+
+	for (i = 0; i < USB_XFERS; i++) {
+		if (prm->ureq[i].req) {
+			if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+				dev_err(&uac2->pdev.dev, "%d Error!\n",
+					__LINE__);
+			continue;
+		}
+
+		req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+		if (req == NULL) {
+			dev_err(&uac2->pdev.dev,
+				"%s:%d Error!\n", __func__, __LINE__);
+			return -EINVAL;
+		}
+
+		prm->ureq[i].req = req;
+		prm->ureq[i].pp = prm;
+
+		req->zero = 0;
+		req->dma = DMA_ADDR_INVALID;
+		req->context = &prm->ureq[i];
+		req->length = prm->max_psize;
+		req->complete =	agdev_iso_complete;
+		req->buf = prm->rbuf + i * req->length;
+
+		if (usb_ep_queue(ep, req, GFP_ATOMIC))
+			dev_err(&uac2->pdev.dev, "%d Error!\n", __LINE__);
+	}
+
+	return 0;
+}
+
+static int
+afunc_get_alt(struct usb_function *fn, unsigned intf)
+{
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+
+	if (intf == INTF_GET(agdev->ac_alt))
+		return ALT_GET(agdev->ac_alt);
+	else if (intf == INTF_GET(agdev->as_out_alt))
+		return ALT_GET(agdev->as_out_alt);
+	else if (intf == INTF_GET(agdev->as_in_alt))
+		return ALT_GET(agdev->as_in_alt);
+	else
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Invalid Interface %d!\n",
+			__func__, __LINE__, intf);
+
+	return -EINVAL;
+}
+
+static void
+afunc_disable(struct usb_function *fn)
+{
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+
+	free_ep(&uac2->p_prm, agdev->in_ep);
+	ALT_SET(agdev->as_in_alt, 0);
+
+	free_ep(&uac2->c_prm, agdev->out_ep);
+	ALT_SET(agdev->as_out_alt, 0);
+}
+
+static int
+in_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	int value = -EOPNOTSUPP;
+
+	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
+		struct cntrl_cur_lay3 c;
+
+		if (entity_id == USB_IN_CLK_ID)
+			c.dCUR = p_srate;
+		else if (entity_id == USB_OUT_CLK_ID)
+			c.dCUR = c_srate;
+
+		value = min_t(unsigned, w_length, sizeof c);
+		memcpy(req->buf, &c, value);
+	} else if (control_selector == UAC2_CS_CONTROL_CLOCK_VALID) {
+		*(u8 *)req->buf = 1;
+		value = min(w_length, (u16) 1);
+	} else {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d control_selector=%d TODO!\n",
+			__func__, __LINE__, control_selector);
+	}
+
+	return value;
+}
+
+static int
+in_rq_range(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_request *req = fn->config->cdev->req;
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 entity_id = (w_index >> 8) & 0xff;
+	u8 control_selector = w_value >> 8;
+	struct cntrl_range_lay3 r;
+	int value = -EOPNOTSUPP;
+
+	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ) {
+		if (entity_id == USB_IN_CLK_ID)
+			r.dMIN = p_srate;
+		else if (entity_id == USB_OUT_CLK_ID)
+			r.dMIN = c_srate;
+		else
+			return -EOPNOTSUPP;
+
+		r.dMAX = r.dMIN;
+		r.dRES = 0;
+		r.wNumSubRanges = 1;
+
+		value = min_t(unsigned, w_length, sizeof r);
+		memcpy(req->buf, &r, value);
+	} else {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d control_selector=%d TODO!\n",
+			__func__, __LINE__, control_selector);
+	}
+
+	return value;
+}
+
+static int
+ac_rq_in(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	if (cr->bRequest == UAC2_CS_CUR)
+		return in_rq_cur(fn, cr);
+	else if (cr->bRequest == UAC2_CS_RANGE)
+		return in_rq_range(fn, cr);
+	else
+		return -EOPNOTSUPP;
+}
+
+static int
+out_rq_cur(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	u16 w_length = le16_to_cpu(cr->wLength);
+	u16 w_value = le16_to_cpu(cr->wValue);
+	u8 control_selector = w_value >> 8;
+
+	if (control_selector == UAC2_CS_CONTROL_SAM_FREQ)
+		return w_length;
+
+	return -EOPNOTSUPP;
+}
+
+static int
+setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	u16 w_index = le16_to_cpu(cr->wIndex);
+	u8 intf = w_index & 0xff;
+
+	if (intf != INTF_GET(agdev->ac_alt)) {
+		dev_err(&uac2->pdev.dev,
+			"%s:%d Error!\n", __func__, __LINE__);
+		return -EOPNOTSUPP;
+	}
+
+	if (cr->bRequestType & USB_DIR_IN)
+		return ac_rq_in(fn, cr);
+	else if (cr->bRequest == UAC2_CS_CUR)
+		return out_rq_cur(fn, cr);
+
+	return -EOPNOTSUPP;
+}
+
+static int
+afunc_setup(struct usb_function *fn, const struct usb_ctrlrequest *cr)
+{
+	struct usb_composite_dev *cdev = fn->config->cdev;
+	struct audio_dev *agdev = func_to_agdev(fn);
+	struct snd_uac2_chip *uac2 = &agdev->uac2;
+	struct usb_request *req = cdev->req;
+	u16 w_length = le16_to_cpu(cr->wLength);
+	int value = -EOPNOTSUPP;
+
+	/* Only Class specific requests are supposed to reach here */
+	if ((cr->bRequestType & USB_TYPE_MASK) != USB_TYPE_CLASS)
+		return -EOPNOTSUPP;
+
+	if ((cr->bRequestType & USB_RECIP_MASK) == USB_RECIP_INTERFACE)
+		value = setup_rq_inf(fn, cr);
+	else
+		dev_err(&uac2->pdev.dev, "%s:%d Error!\n", __func__, __LINE__);
+
+	if (value >= 0) {
+		req->length = value;
+		req->zero = value < w_length;
+		value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC);
+		if (value < 0) {
+			dev_err(&uac2->pdev.dev,
+				"%s:%d Error!\n", __func__, __LINE__);
+			req->status = 0;
+		}
+	}
+
+	return value;
+}
+
+static int
+uac2_bind_config(struct usb_configuration *cfg)
+{
+	int id, res;
+
+	agdev_g = kzalloc(sizeof *agdev_g, GFP_KERNEL);
+	if (agdev_g == NULL) {
+		printk(KERN_ERR "Unable to allocate audio gadget\n");
+		return -ENOMEM;
+	}
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_ASSOC].id = id;
+	iad_desc.iFunction = id,
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_IF_CTRL].id = id;
+	std_ac_if_desc.iInterface = id,
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_CLKSRC_IN].id = id;
+	in_clk_src_desc.iClockSource = id,
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_CLKSRC_OUT].id = id;
+	out_clk_src_desc.iClockSource = id,
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_USB_IT].id = id;
+	usb_out_it_desc.iTerminal = id,
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_IO_IT].id = id;
+	io_in_it_desc.iTerminal = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_USB_OT].id = id;
+	usb_in_ot_desc.iTerminal = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_IO_OT].id = id;
+	io_out_ot_desc.iTerminal = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_AS_OUT_ALT0].id = id;
+	std_as_out_if0_desc.iInterface = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_AS_OUT_ALT1].id = id;
+	std_as_out_if1_desc.iInterface = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_AS_IN_ALT0].id = id;
+	std_as_in_if0_desc.iInterface = id;
+
+	id = usb_string_id(cfg->cdev);
+	if (id < 0)
+		return id;
+
+	strings_fn[STR_AS_IN_ALT1].id = id;
+	std_as_in_if1_desc.iInterface = id;
+
+	agdev_g->func.name = "uac2_func";
+	agdev_g->func.strings = fn_strings;
+	agdev_g->func.bind = afunc_bind;
+	agdev_g->func.unbind = afunc_unbind;
+	agdev_g->func.set_alt = afunc_set_alt;
+	agdev_g->func.get_alt = afunc_get_alt;
+	agdev_g->func.disable = afunc_disable;
+	agdev_g->func.setup = afunc_setup;
+
+	/* Initialize the configurable parameters */
+	usb_out_it_desc.bNrChannels = num_channels(c_chmask);
+	usb_out_it_desc.bmChannelConfig = cpu_to_le32(c_chmask);
+	io_in_it_desc.bNrChannels = num_channels(p_chmask);
+	io_in_it_desc.bmChannelConfig = cpu_to_le32(p_chmask);
+	as_out_hdr_desc.bNrChannels = num_channels(c_chmask);
+	as_out_hdr_desc.bmChannelConfig = cpu_to_le32(c_chmask);
+	as_in_hdr_desc.bNrChannels = num_channels(p_chmask);
+	as_in_hdr_desc.bmChannelConfig = cpu_to_le32(p_chmask);
+	as_out_fmt1_desc.bSubslotSize = c_ssize;
+	as_out_fmt1_desc.bBitResolution = c_ssize * 8;
+	as_in_fmt1_desc.bSubslotSize = p_ssize;
+	as_in_fmt1_desc.bBitResolution = p_ssize * 8;
+
+	snprintf(clksrc_in, sizeof(clksrc_in), "%uHz", p_srate);
+	snprintf(clksrc_out, sizeof(clksrc_out), "%uHz", c_srate);
+
+	res = usb_add_function(cfg, &agdev_g->func);
+	if (res < 0)
+		kfree(agdev_g);
+
+	return res;
+}
+
+static void
+uac2_unbind_config(struct usb_configuration *cfg)
+{
+	kfree(agdev_g);
+	agdev_g = NULL;
+}
-- 
1.7.4.1

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