USB Audio Gadget refactoring

Abstract the peripheral side ALSA sound card code from the f_uac2 function into a component that can be called by various functions, so the various flavors can be split apart and selectively reused.

Visible changes:
- add uac_params structure to pass audio paramteres for g_audio_setup
- make ALSA sound card's name configurable
- add [in/out]_ep_maxpsize
- allocate snd_uac_chip structure during g_audio_setup
- add u_audio_[start/stop]_[capture/playback] functions

Signed-off-by Ruslan Bilovol <[email protected]>

---
 drivers/usb/gadget/Kconfig            |   4 +
 drivers/usb/gadget/function/Makefile  |   1 +
 drivers/usb/gadget/function/f_uac2.c  | 721 ++++------------------------------
 drivers/usb/gadget/function/u_audio.c | 661 +++++++++++++++++++++++++++++++
 drivers/usb/gadget/function/u_audio.h |  95 +++++
 drivers/usb/gadget/legacy/Kconfig     |   1 +
 6 files changed, 846 insertions(+), 637 deletions(-)
 create mode 100644 drivers/usb/gadget/function/u_audio.c
 create mode 100644 drivers/usb/gadget/function/u_audio.h

drivers/usb/gadget/Kconfig +4 -0

index c164d6b..2ba0ace 100644
@@ -158,6 +158,9 @@ config USB_U_SERIAL
 config USB_U_ETHER
        tristate
 
+config USB_U_AUDIO
+       tristate
+
 config USB_F_SERIAL
        tristate
 

@@ -381,6 +384,7 @@ config USB_CONFIGFS_F_UAC2
        depends on SND
        select USB_LIBCOMPOSITE
        select SND_PCM
+       select USB_U_AUDIO
        select USB_F_UAC2
        help
          This Audio function is compatible with USB Audio Class

drivers/usb/gadget/function/Makefile +1 -0

index cb8c225..b29f2ae 100644
@@ -32,6 +32,7 @@ usb_f_mass_storage-y          := f_mass_storage.o storage_common.o
 obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o
 usb_f_fs-y                     := f_fs.o
 obj-$(CONFIG_USB_F_FS)         += usb_f_fs.o
+obj-$(CONFIG_USB_U_AUDIO)      += u_audio.o
 usb_f_uac1-y                   := f_uac1.o u_uac1.o
 obj-$(CONFIG_USB_F_UAC1)       += usb_f_uac1.o
 usb_f_uac2-y                   := f_uac2.o

drivers/usb/gadget/function/f_uac2.c +82 -636

index d4565b5..059a14a 100644
@@ -15,10 +15,7 @@
 #include <linux/usb/audio-v2.h>
 #include <linux/module.h>
 
-#include <sound/core.h>
-#include <sound/pcm.h>
-#include <sound/pcm_params.h>
-
+#include "u_audio.h"
 #include "u_uac2.h"
 
 /*

@@ -50,455 +47,23 @@
 #define UNFLW_CTRL     8
 #define OVFLW_CTRL     10
 
-struct uac2_req {
-       struct uac2_rtd_params *pp; /* parent param */
-       struct usb_request *req;
-};
-
-struct uac2_rtd_params {
-       struct snd_uac2_chip *uac2; /* parent chip */
-       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;
-
-       spinlock_t lock;
-};
-
-struct snd_uac2_chip {
-       struct uac2_rtd_params p_prm;
-       struct uac2_rtd_params c_prm;
-
-       struct snd_card *card;
-       struct snd_pcm *pcm;
-
-       /* timekeeping for the playback endpoint */
-       unsigned int p_interval;
-       unsigned int p_residue;
-
-       /* pre-calculated values for playback iso completion */
-       unsigned int p_pktsize;
-       unsigned int p_pktsize_residue;
-       unsigned int p_framesize;
+struct f_uac2 {
+       struct g_audio g_audio;
+       u8 ac_intf, as_in_intf, as_out_intf;
+       u8 ac_alt, as_in_alt, as_out_alt;       /* needed for get_alt() */
 };
 
-#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 {
-       u8 ac_intf, ac_alt;
-       u8 as_out_intf, as_out_alt;
-       u8 as_in_intf, as_in_alt;
-
-       struct usb_ep *in_ep, *out_ep;
-       struct usb_function func;
-       struct usb_gadget *gadget;
-
-       /* The ALSA Sound Card it represents on the USB-Client side */
-       struct snd_uac2_chip uac2;
-};
-
-static inline
-struct audio_dev *func_to_agdev(struct usb_function *f)
+static inline struct f_uac2 *func_to_uac2(struct usb_function *f)
 {
-       return container_of(f, struct audio_dev, func);
+       return container_of(f, struct f_uac2, g_audio.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 f_uac2_opts *agdev_to_uac2_opts(struct audio_dev *agdev)
+struct f_uac2_opts *g_audio_to_uac2_opts(struct g_audio *agdev)
 {
        return container_of(agdev->func.fi, struct f_uac2_opts, func_inst);
 }
 
-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;
-       unsigned int hw_ptr;
-       bool update_alsa = false;
-       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->uac2;
-
-       /* i/f shutting down */
-       if (!prm->ep_enabled || req->status == -ESHUTDOWN)
-               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) {
-               /*
-                * For each IN packet, take the quotient of the current data
-                * rate and the endpoint's interval as the base packet size.
-                * If there is a residue from this division, add it to the
-                * residue accumulator.
-                */
-               req->length = uac2->p_pktsize;
-               uac2->p_residue += uac2->p_pktsize_residue;
-
-               /*
-                * Whenever there are more bytes in the accumulator than we
-                * need to add one more sample frame, increase this packet's
-                * size and decrease the accumulator.
-                */
-               if (uac2->p_residue / uac2->p_interval >= uac2->p_framesize) {
-                       req->length += uac2->p_framesize;
-                       uac2->p_residue -= uac2->p_framesize *
-                                          uac2->p_interval;
-               }
-
-               req->actual = req->length;
-       }
-
-       pending = prm->hw_ptr % prm->period_size;
-       pending += req->actual;
-       if (pending >= prm->period_size)
-               update_alsa = true;
-
-       hw_ptr = prm->hw_ptr;
-       prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
-
-       spin_unlock_irqrestore(&prm->lock, flags);
-
-       /* Pack USB load in ALSA ring buffer */
-       pending = prm->dma_bytes - hw_ptr;
-
-       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
-               if (unlikely(pending < req->actual)) {
-                       memcpy(req->buf, prm->dma_area + hw_ptr, pending);
-                       memcpy(req->buf + pending, prm->dma_area,
-                              req->actual - pending);
-               } else {
-                       memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);
-               }
-       } else {
-               if (unlikely(pending < req->actual)) {
-                       memcpy(prm->dma_area + hw_ptr, req->buf, pending);
-                       memcpy(prm->dma_area, req->buf + pending,
-                              req->actual - pending);
-               } else {
-                       memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);
-               }
-       }
-
-exit:
-       if (usb_ep_queue(ep, req, GFP_ATOMIC))
-               dev_err(uac2->card->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 f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
-       struct uac2_rtd_params *prm;
-       unsigned long flags;
-       int err = 0;
-
-       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
-               prm = &uac2->p_prm;
-       else
-               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 * uac2_opts->req_number);
-
-       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;
-       struct audio_dev *audio_dev;
-       struct f_uac2_opts *opts;
-       int p_ssize, c_ssize;
-       int p_srate, c_srate;
-       int p_chmask, c_chmask;
-
-       audio_dev = uac2_to_agdev(uac2);
-       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
-       p_ssize = opts->p_ssize;
-       c_ssize = opts->c_ssize;
-       p_srate = opts->p_srate;
-       c_srate = opts->c_srate;
-       p_chmask = opts->p_chmask;
-       c_chmask = opts->c_chmask;
-       uac2->p_residue = 0;
-
-       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;
-               switch (p_ssize) {
-               case 3:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-                       break;
-               case 4:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-                       break;
-               default:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-                       break;
-               }
-               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;
-               switch (c_ssize) {
-               case 3:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-                       break;
-               case 4:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-                       break;
-               default:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-                       break;
-               }
-               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 snd_uac2_probe(struct audio_dev *audio_dev)
-{
-       struct snd_uac2_chip *uac2 = &audio_dev->uac2;
-       struct snd_card *card;
-       struct snd_pcm *pcm;
-       struct f_uac2_opts *opts;
-       int err;
-       int p_chmask, c_chmask;
-
-       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
-       p_chmask = opts->p_chmask;
-       c_chmask = opts->c_chmask;
-
-       /* Choose any slot, with no id */
-       err = snd_card_new(&audio_dev->gadget->dev,
-                       -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_Gadget");
-       strcpy(card->shortname, "UAC2_Gadget");
-       sprintf(card->longname, "UAC2_Gadget %i", card->dev->id);
-
-       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)
-               return 0;
-
-snd_fail:
-       snd_card_free(card);
-
-       uac2->pcm = NULL;
-       uac2->card = NULL;
-
-       return err;
-}
-
-static int snd_uac2_remove(struct audio_dev *audio_dev)
-{
-       struct snd_card *card = audio_dev->uac2.card;
-
-       if (card)
-               return snd_card_free(card);
-
-       return 0;
-}
-
-
 /* --------- USB Function Interface ------------- */
 
 enum {

@@ -886,32 +451,6 @@ struct cntrl_range_lay3 {
        __u32   dRES;
 } __packed;
 
-static inline void
-free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
-{
-       struct snd_uac2_chip *uac2 = prm->uac2;
-       struct audio_dev *agdev = uac2_to_agdev(uac2);
-       struct f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
-       int i;
-
-       if (!prm->ep_enabled)
-               return;
-
-       prm->ep_enabled = false;
-
-       for (i = 0; i < uac2_opts->req_number; 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->card->dev,
-                       "%s:%d Error!\n", __func__, __LINE__);
-}
-
 static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        struct usb_endpoint_descriptor *ep_desc,
        unsigned int factor, bool is_playback)

@@ -938,12 +477,11 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 static int
 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 f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
        struct usb_composite_dev *cdev = cfg->cdev;
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
-       struct uac2_rtd_params *prm;
        struct f_uac2_opts *uac2_opts;
        struct usb_string *us;
        int ret;

@@ -990,8 +528,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return ret;
        }
        std_ac_if_desc.bInterfaceNumber = ret;
-       agdev->ac_intf = ret;
-       agdev->ac_alt = 0;
+       uac2->ac_intf = ret;
+       uac2->ac_alt = 0;
 
        ret = usb_interface_id(cfg, fn);
        if (ret < 0) {

@@ -1000,8 +538,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        }
        std_as_out_if0_desc.bInterfaceNumber = ret;
        std_as_out_if1_desc.bInterfaceNumber = ret;
-       agdev->as_out_intf = ret;
-       agdev->as_out_alt = 0;
+       uac2->as_out_intf = ret;
+       uac2->as_out_alt = 0;
 
        ret = usb_interface_id(cfg, fn);
        if (ret < 0) {

@@ -1010,8 +548,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        }
        std_as_in_if0_desc.bInterfaceNumber = ret;
        std_as_in_if1_desc.bInterfaceNumber = ret;
-       agdev->as_in_intf = ret;
-       agdev->as_in_alt = 0;
+       uac2->as_in_intf = ret;
+       uac2->as_in_alt = 0;
 
        agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
        if (!agdev->out_ep) {

@@ -1025,15 +563,17 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return ret;
        }
 
-       uac2->p_prm.uac2 = uac2;
-       uac2->c_prm.uac2 = uac2;
-
        /* Calculate wMaxPacketSize according to audio bandwidth */
        set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000, true);
        set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000, false);
        set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000, true);
        set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000, false);
 
+       agdev->in_ep_maxpsize = max(fs_epin_desc.wMaxPacketSize,
+                                       hs_epin_desc.wMaxPacketSize);
+       agdev->out_ep_maxpsize = max(fs_epout_desc.wMaxPacketSize,
+                                       hs_epout_desc.wMaxPacketSize);
+
        hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
        hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
 

@@ -1044,46 +584,18 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 
        agdev->gadget = gadget;
 
-       prm = &agdev->uac2.c_prm;
-       prm->max_psize = hs_epout_desc.wMaxPacketSize;
-       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
-                       GFP_KERNEL);
-       if (!prm->ureq) {
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
-       if (!prm->rbuf) {
-               prm->max_psize = 0;
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-
-       prm = &agdev->uac2.p_prm;
-       prm->max_psize = hs_epin_desc.wMaxPacketSize;
-       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
-                       GFP_KERNEL);
-       if (!prm->ureq) {
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
-       if (!prm->rbuf) {
-               prm->max_psize = 0;
-               ret = -ENOMEM;
-               goto err_no_memory;
-       }
-
-       ret = snd_uac2_probe(agdev);
+       agdev->params.p_chmask = uac2_opts->p_chmask;
+       agdev->params.p_srate = uac2_opts->p_srate;
+       agdev->params.p_ssize = uac2_opts->p_ssize;
+       agdev->params.c_chmask = uac2_opts->c_chmask;
+       agdev->params.c_srate = uac2_opts->c_srate;
+       agdev->params.c_ssize = uac2_opts->c_ssize;
+       agdev->params.req_number = uac2_opts->req_number;
+       ret = g_audio_setup(agdev, "UAC2 PCM", "UAC2_Gadget");
        if (ret)
-               goto err_no_memory;
+               goto err_free_descs;
        return 0;
 
-err_no_memory:
-       kfree(agdev->uac2.p_prm.ureq);
-       kfree(agdev->uac2.c_prm.ureq);
-       kfree(agdev->uac2.p_prm.rbuf);
-       kfree(agdev->uac2.c_prm.rbuf);
 err_free_descs:
        usb_free_all_descriptors(fn);
        agdev->gadget = NULL;

@@ -1094,15 +606,10 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 f_uac2_opts *opts = agdev_to_uac2_opts(agdev);
-       struct snd_uac2_chip *uac2 = &agdev->uac2;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
-       struct usb_request *req;
-       struct usb_ep *ep;
-       struct uac2_rtd_params *prm;
-       int req_len, i;
+       int ret = 0;
 
        /* No i/f has more than 2 alt settings */
        if (alt > 1) {

@@ -1110,7 +617,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return -EINVAL;
        }
 
-       if (intf == agdev->ac_intf) {
+       if (intf == uac2->ac_intf) {
                /* Control I/f has only 1 AltSetting - 0 */
                if (alt) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

@@ -1119,92 +626,40 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return 0;
        }
 
-       if (intf == agdev->as_out_intf) {
-               ep = agdev->out_ep;
-               prm = &uac2->c_prm;
-               config_ep_by_speed(gadget, fn, ep);
-               agdev->as_out_alt = alt;
-               req_len = prm->max_psize;
-       } else if (intf == agdev->as_in_intf) {
-               unsigned int factor, rate;
-               struct usb_endpoint_descriptor *ep_desc;
-
-               ep = agdev->in_ep;
-               prm = &uac2->p_prm;
-               config_ep_by_speed(gadget, fn, ep);
-               agdev->as_in_alt = alt;
-
-               /* pre-calculate the playback endpoint's interval */
-               if (gadget->speed == USB_SPEED_FULL) {
-                       ep_desc = &fs_epin_desc;
-                       factor = 1000;
-               } else {
-                       ep_desc = &hs_epin_desc;
-                       factor = 8000;
-               }
-
-               /* pre-compute some values for iso_complete() */
-               uac2->p_framesize = opts->p_ssize *
-                                   num_channels(opts->p_chmask);
-               rate = opts->p_srate * uac2->p_framesize;
-               uac2->p_interval = factor / (1 << (ep_desc->bInterval - 1));
-               uac2->p_pktsize = min_t(unsigned int, rate / uac2->p_interval,
-                                       prm->max_psize);
+       if (intf == uac2->as_out_intf) {
+               uac2->as_out_alt = alt;
 
-               if (uac2->p_pktsize < prm->max_psize)
-                       uac2->p_pktsize_residue = rate % uac2->p_interval;
+               if (alt)
+                       ret = u_audio_start_capture(&uac2->g_audio);
                else
-                       uac2->p_pktsize_residue = 0;
+                       u_audio_stop_capture(&uac2->g_audio);
+       } else if (intf == uac2->as_in_intf) {
+               uac2->as_in_alt = alt;
 
-               req_len = uac2->p_pktsize;
-               uac2->p_residue = 0;
+               if (alt)
+                       ret = u_audio_start_playback(&uac2->g_audio);
+               else
+                       u_audio_stop_playback(&uac2->g_audio);
        } else {
                dev_err(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 < opts->req_number; i++) {
-               if (!prm->ureq[i].req) {
-                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
-                       if (req == NULL)
-                               return -ENOMEM;
-
-                       prm->ureq[i].req = req;
-                       prm->ureq[i].pp = prm;
-
-                       req->zero = 0;
-                       req->context = &prm->ureq[i];
-                       req->length = req_len;
-                       req->complete = agdev_iso_complete;
-                       req->buf = prm->rbuf + i * prm->max_psize;
-               }
-
-               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
-                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
-       }
-
-       return 0;
+       return ret;
 }
 
 static int
 afunc_get_alt(struct usb_function *fn, unsigned intf)
 {
-       struct audio_dev *agdev = func_to_agdev(fn);
-
-       if (intf == agdev->ac_intf)
-               return agdev->ac_alt;
-       else if (intf == agdev->as_out_intf)
-               return agdev->as_out_alt;
-       else if (intf == agdev->as_in_intf)
-               return agdev->as_in_alt;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
+
+       if (intf == uac2->ac_intf)
+               return uac2->ac_alt;
+       else if (intf == uac2->as_out_intf)
+               return uac2->as_out_alt;
+       else if (intf == uac2->as_in_intf)
+               return uac2->as_in_alt;
        else
                dev_err(&agdev->gadget->dev,
                        "%s:%d Invalid Interface %d!\n",

@@ -1216,21 +671,19 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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);
-       agdev->as_in_alt = 0;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
 
-       free_ep(&uac2->c_prm, agdev->out_ep);
-       agdev->as_out_alt = 0;
+       uac2->as_in_alt = 0;
+       uac2->as_out_alt = 0;
+       u_audio_stop_capture(&uac2->g_audio);
+       u_audio_stop_playback(&uac2->g_audio);
 }
 
 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 g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts;
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);

@@ -1240,7 +693,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        int value = -EOPNOTSUPP;
        int p_srate, c_srate;
 
-       opts = agdev_to_uac2_opts(agdev);
+       opts = g_audio_to_uac2_opts(agdev);
        p_srate = opts->p_srate;
        c_srate = opts->c_srate;
 

@@ -1271,7 +724,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts;
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);

@@ -1282,7 +735,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        int value = -EOPNOTSUPP;
        int p_srate, c_srate;
 
-       opts = agdev_to_uac2_opts(agdev);
+       opts = g_audio_to_uac2_opts(agdev);
        p_srate = opts->p_srate;
        c_srate = opts->c_srate;
 

@@ -1336,11 +789,12 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 static int
 setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
 {
-       struct audio_dev *agdev = func_to_agdev(fn);
+       struct f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u8 intf = w_index & 0xff;
 
-       if (intf != agdev->ac_intf) {
+       if (intf != uac2->ac_intf) {
                dev_err(&agdev->gadget->dev,
                        "%s:%d Error!\n", __func__, __LINE__);
                return -EOPNOTSUPP;

@@ -1358,7 +812,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 g_audio *agdev = func_to_g_audio(fn);
        struct usb_request *req = cdev->req;
        u16 w_length = le16_to_cpu(cr->wLength);
        int value = -EOPNOTSUPP;

@@ -1504,10 +958,10 @@ static struct usb_function_instance *afunc_alloc_inst(void)
 
 static void afunc_free(struct usb_function *f)
 {
-       struct audio_dev *agdev;
+       struct g_audio *agdev;
        struct f_uac2_opts *opts;
 
-       agdev = func_to_agdev(f);
+       agdev = func_to_g_audio(f);
        opts = container_of(f->fi, struct f_uac2_opts, func_inst);
        kfree(agdev);
        mutex_lock(&opts->lock);

@@ -1517,17 +971,9 @@ static void afunc_free(struct usb_function *f)
 
 static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
 {
-       struct audio_dev *agdev = func_to_agdev(f);
-       struct uac2_rtd_params *prm;
-
-       snd_uac2_remove(agdev);
-
-       prm = &agdev->uac2.p_prm;
-       kfree(prm->rbuf);
+       struct g_audio *agdev = func_to_g_audio(f);
 
-       prm = &agdev->uac2.c_prm;
-       kfree(prm->rbuf);
-       kfree(prm->ureq);
+       g_audio_cleanup(agdev);
        usb_free_all_descriptors(f);
 
        agdev->gadget = NULL;

@@ -1535,11 +981,11 @@ static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
 
 static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
 {
-       struct audio_dev *agdev;
+       struct f_uac2   *uac2;
        struct f_uac2_opts *opts;
 
-       agdev = kzalloc(sizeof(*agdev), GFP_KERNEL);
-       if (agdev == NULL)
+       uac2 = kzalloc(sizeof(*uac2), GFP_KERNEL);
+       if (uac2 == NULL)
                return ERR_PTR(-ENOMEM);
 
        opts = container_of(fi, struct f_uac2_opts, func_inst);

@@ -1547,19 +993,20 @@ static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
        ++opts->refcnt;
        mutex_unlock(&opts->lock);
 
-       agdev->func.name = "uac2_func";
-       agdev->func.bind = afunc_bind;
-       agdev->func.unbind = afunc_unbind;
-       agdev->func.set_alt = afunc_set_alt;
-       agdev->func.get_alt = afunc_get_alt;
-       agdev->func.disable = afunc_disable;
-       agdev->func.setup = afunc_setup;
-       agdev->func.free_func = afunc_free;
+       uac2->g_audio.func.name = "uac2_func";
+       uac2->g_audio.func.bind = afunc_bind;
+       uac2->g_audio.func.unbind = afunc_unbind;
+       uac2->g_audio.func.set_alt = afunc_set_alt;
+       uac2->g_audio.func.get_alt = afunc_get_alt;
+       uac2->g_audio.func.disable = afunc_disable;
+       uac2->g_audio.func.setup = afunc_setup;
+       uac2->g_audio.func.free_func = afunc_free;

drivers/usb/gadget/function/u_audio.c new file +1 -0

new file mode 100644
index 0000000..8ee65b8
@@ -0,0 +1,661 @@
+/*

drivers/usb/gadget/function/u_audio.c new file +650 -0

+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "u_audio.h"
+
+#define BUFF_SIZE_MAX  (PAGE_SIZE * 16)
+#define PRD_SIZE_MAX   PAGE_SIZE
+#define MIN_PERIODS    4
+
+struct uac_req {
+       struct uac_rtd_params *pp; /* parent param */
+       struct usb_request *req;
+};
+
+/* Runtime data params for one stream */
+struct uac_rtd_params {
+       struct snd_uac_chip *uac; /* parent chip */
+       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;     /* MaxPacketSize of endpoint */
+       struct uac_req *ureq;
+
+       spinlock_t lock;
+};
+
+struct snd_uac_chip {
+       struct g_audio *audio_dev;
+
+       struct uac_rtd_params p_prm;
+       struct uac_rtd_params c_prm;
+
+       struct snd_card *card;
+       struct snd_pcm *pcm;
+
+       /* timekeeping for the playback endpoint */
+       unsigned int p_interval;
+       unsigned int p_residue;
+
+       /* pre-calculated values for playback iso completion */
+       unsigned int p_pktsize;
+       unsigned int p_pktsize_residue;
+       unsigned int p_framesize;
+};
+
+static struct snd_pcm_hardware uac_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,
+};
+
+static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       unsigned pending;
+       unsigned long flags;
+       unsigned int hw_ptr;
+       bool update_alsa = false;
+       int status = req->status;
+       struct uac_req *ur = req->context;
+       struct snd_pcm_substream *substream;
+       struct uac_rtd_params *prm = ur->pp;
+       struct snd_uac_chip *uac = prm->uac;
+
+       /* i/f shutting down */
+       if (!prm->ep_enabled || req->status == -ESHUTDOWN)
+               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) {
+               /*
+                * For each IN packet, take the quotient of the current data
+                * rate and the endpoint's interval as the base packet size.
+                * If there is a residue from this division, add it to the
+                * residue accumulator.
+                */
+               req->length = uac->p_pktsize;
+               uac->p_residue += uac->p_pktsize_residue;
+
+               /*
+                * Whenever there are more bytes in the accumulator than we
+                * need to add one more sample frame, increase this packet's
+                * size and decrease the accumulator.
+                */
+               if (uac->p_residue / uac->p_interval >= uac->p_framesize) {
+                       req->length += uac->p_framesize;
+                       uac->p_residue -= uac->p_framesize *
+                                          uac->p_interval;
+               }
+
+               req->actual = req->length;
+       }
+
+       pending = prm->hw_ptr % prm->period_size;
+       pending += req->actual;
+       if (pending >= prm->period_size)
+               update_alsa = true;
+
+       hw_ptr = prm->hw_ptr;
+       prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
+
+       spin_unlock_irqrestore(&prm->lock, flags);
+
+       /* Pack USB load in ALSA ring buffer */
+       pending = prm->dma_bytes - hw_ptr;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+               if (unlikely(pending < req->actual)) {
+                       memcpy(req->buf, prm->dma_area + hw_ptr, pending);
+                       memcpy(req->buf + pending, prm->dma_area,
+                              req->actual - pending);
+               } else {
+                       memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);
+               }
+       } else {
+               if (unlikely(pending < req->actual)) {
+                       memcpy(prm->dma_area + hw_ptr, req->buf, pending);
+                       memcpy(prm->dma_area, req->buf + pending,
+                              req->actual - pending);
+               } else {
+                       memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);
+               }
+       }
+
+exit:
+       if (usb_ep_queue(ep, req, GFP_ATOMIC))
+               dev_err(uac->card->dev, "%d Error!\n", __LINE__);
+
+       if (update_alsa)
+               snd_pcm_period_elapsed(substream);
+}
+
+static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       unsigned long flags;
+       int err = 0;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->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 * params->req_number);
+
+       return err;
+}
+
+static snd_pcm_uframes_t uac_pcm_pointer(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->c_prm;
+
+       return bytes_to_frames(substream->runtime, prm->hw_ptr);
+}
+
+static int uac_pcm_hw_params(struct snd_pcm_substream *substream,
+                              struct snd_pcm_hw_params *hw_params)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+       int err;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->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 uac_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->c_prm;
+
+       prm->dma_area = NULL;
+       prm->dma_bytes = 0;
+       prm->period_size = 0;
+
+       return snd_pcm_lib_free_pages(substream);
+}
+
+static int uac_pcm_open(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       int p_ssize, c_ssize;
+       int p_srate, c_srate;
+       int p_chmask, c_chmask;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+       p_ssize = params->p_ssize;
+       c_ssize = params->c_ssize;
+       p_srate = params->p_srate;
+       c_srate = params->c_srate;
+       p_chmask = params->p_chmask;
+       c_chmask = params->c_chmask;
+       uac->p_residue = 0;
+
+       runtime->hw = uac_pcm_hardware;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+               spin_lock_init(&uac->p_prm.lock);
+               runtime->hw.rate_min = p_srate;
+               switch (p_ssize) {
+               case 3:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
+                       break;
+               case 4:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
+                       break;
+               default:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
+                       break;
+               }
+               runtime->hw.channels_min = num_channels(p_chmask);
+               runtime->hw.period_bytes_min = 2 * uac->p_prm.max_psize
+                                               / runtime->hw.periods_min;
+       } else {
+               spin_lock_init(&uac->c_prm.lock);
+               runtime->hw.rate_min = c_srate;
+               switch (c_ssize) {
+               case 3:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
+                       break;
+               case 4:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
+                       break;
+               default:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
+                       break;
+               }
+               runtime->hw.channels_min = num_channels(c_chmask);
+               runtime->hw.period_bytes_min = 2 * uac->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 uac_pcm_null(struct snd_pcm_substream *substream)
+{
+       return 0;
+}
+
+static struct snd_pcm_ops uac_pcm_ops = {
+       .open = uac_pcm_open,
+       .close = uac_pcm_null,
+       .ioctl = snd_pcm_lib_ioctl,
+       .hw_params = uac_pcm_hw_params,
+       .hw_free = uac_pcm_hw_free,
+       .trigger = uac_pcm_trigger,
+       .pointer = uac_pcm_pointer,
+       .prepare = uac_pcm_null,
+};
+
+static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
+{
+       struct snd_uac_chip *uac = prm->uac;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       int i;
+
+       if (!prm->ep_enabled)
+               return;
+
+       prm->ep_enabled = false;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+
+       for (i = 0; i < params->req_number; 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(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);
+}
+
+
+int u_audio_start_capture(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+       struct usb_gadget *gadget = audio_dev->gadget;
+       struct device *dev = &gadget->dev;
+       struct usb_request *req;
+       struct usb_ep *ep;
+       struct uac_rtd_params *prm;
+       struct uac_params *params = &audio_dev->params;
+       int req_len, i;
+
+       ep = audio_dev->out_ep;
+       prm = &uac->c_prm;
+       config_ep_by_speed(gadget, &audio_dev->func, ep);
+       req_len = prm->max_psize;
+
+       prm->ep_enabled = true;
+       usb_ep_enable(ep);
+
+       for (i = 0; i < params->req_number; i++) {
+               if (!prm->ureq[i].req) {
+                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+                       if (req == NULL)
+                               return -ENOMEM;
+
+                       prm->ureq[i].req = req;
+                       prm->ureq[i].pp = prm;
+
+                       req->zero = 0;
+                       req->context = &prm->ureq[i];
+                       req->length = req_len;
+                       req->complete = u_audio_iso_complete;
+                       req->buf = prm->rbuf + i * prm->max_psize;
+               }
+
+               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(u_audio_start_capture);
+
+void u_audio_stop_capture(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+
+       free_ep(&uac->c_prm, audio_dev->out_ep);
+}
+EXPORT_SYMBOL_GPL(u_audio_stop_capture);
+
+int u_audio_start_playback(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+       struct usb_gadget *gadget = audio_dev->gadget;
+       struct device *dev = &gadget->dev;
+       struct usb_request *req;
+       struct usb_ep *ep;
+       struct uac_rtd_params *prm;
+       struct uac_params *params = &audio_dev->params;
+       unsigned int factor, rate;
+       const struct usb_endpoint_descriptor *ep_desc;
+       int req_len, i;
+
+       ep = audio_dev->in_ep;
+       prm = &uac->p_prm;
+       config_ep_by_speed(gadget, &audio_dev->func, ep);
+
+       ep_desc = ep->desc;
+
+       /* pre-calculate the playback endpoint's interval */
+       if (gadget->speed == USB_SPEED_FULL)
+               factor = 1000;
+       else
+               factor = 8000;
+
+       /* pre-compute some values for iso_complete() */
+       uac->p_framesize = params->p_ssize *
+                           num_channels(params->p_chmask);
+       rate = params->p_srate * uac->p_framesize;
+       uac->p_interval = factor / (1 << (ep_desc->bInterval - 1));
+       uac->p_pktsize = min_t(unsigned int, rate / uac->p_interval,
+                               prm->max_psize);
+
+       if (uac->p_pktsize < prm->max_psize)
+               uac->p_pktsize_residue = rate % uac->p_interval;
+       else
+               uac->p_pktsize_residue = 0;
+
+       req_len = uac->p_pktsize;
+       uac->p_residue = 0;
+
+       prm->ep_enabled = true;
+       usb_ep_enable(ep);
+
+       for (i = 0; i < params->req_number; i++) {
+               if (!prm->ureq[i].req) {
+                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+                       if (req == NULL)
+                               return -ENOMEM;
+
+                       prm->ureq[i].req = req;
+                       prm->ureq[i].pp = prm;
+
+                       req->zero = 0;
+                       req->context = &prm->ureq[i];
+                       req->length = req_len;
+                       req->complete = u_audio_iso_complete;
+                       req->buf = prm->rbuf + i * prm->max_psize;
+               }
+
+               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(u_audio_start_playback);
+
+void u_audio_stop_playback(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+
+       free_ep(&uac->p_prm, audio_dev->in_ep);
+}
+EXPORT_SYMBOL_GPL(u_audio_stop_playback);
+
+int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
+                                       const char *card_name)
+{
+       struct snd_uac_chip *uac;
+       struct snd_card *card;
+       struct snd_pcm *pcm;
+       struct uac_params *params;
+       int p_chmask, c_chmask;
+       int err;
+
+       if (!g_audio)
+               return -EINVAL;
+
+       uac = kzalloc(sizeof(*uac), GFP_KERNEL);
+       if (!uac)
+               return -ENOMEM;
+       g_audio->uac = uac;
+       uac->audio_dev = g_audio;
+
+       params = &g_audio->params;
+       p_chmask = params->p_chmask;
+       c_chmask = params->c_chmask;
+
+       if (c_chmask) {
+               struct uac_rtd_params *prm = &uac->c_prm;
+
+               uac->c_prm.uac = uac;
+               prm->max_psize = g_audio->out_ep_maxpsize;
+
+               prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
+                               GFP_KERNEL);
+               if (!prm->ureq) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+
+               prm->rbuf = kcalloc(params->req_number, prm->max_psize,
+                               GFP_KERNEL);
+               if (!prm->rbuf) {
+                       prm->max_psize = 0;
+                       err = -ENOMEM;
+                       goto fail;
+               }
+       }
+
+       if (p_chmask) {
+               struct uac_rtd_params *prm = &uac->p_prm;
+
+               uac->p_prm.uac = uac;
+               prm->max_psize = g_audio->in_ep_maxpsize;
+
+               prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
+                               GFP_KERNEL);
+               if (!prm->ureq) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+
+               prm->rbuf = kcalloc(params->req_number, prm->max_psize,
+                               GFP_KERNEL);
+               if (!prm->rbuf) {
+                       prm->max_psize = 0;
+                       err = -ENOMEM;
+                       goto fail;
+               }
+       }
+
+       /* Choose any slot, with no id */
+       err = snd_card_new(&g_audio->gadget->dev,
+                       -1, NULL, THIS_MODULE, 0, &card);
+       if (err < 0)
+               goto fail;
+
+       uac->card = card;
+
+       /*
+        * Create first PCM device
+        * Create a substream only for non-zero channel streams
+        */
+       err = snd_pcm_new(uac->card, pcm_name, 0,
+                              p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);
+       if (err < 0)
+               goto snd_fail;
+
+       strcpy(pcm->name, pcm_name);
+       pcm->private_data = uac;
+       uac->pcm = pcm;
+
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac_pcm_ops);
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac_pcm_ops);
+
+       strcpy(card->driver, card_name);
+       strcpy(card->shortname, card_name);
+       sprintf(card->longname, "%s %i", card_name, card->dev->id);
+
+       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)
+               return 0;
+
+snd_fail:
+       snd_card_free(card);
+fail:
+       kfree(uac->p_prm.ureq);
+       kfree(uac->c_prm.ureq);
+       kfree(uac->p_prm.rbuf);
+       kfree(uac->c_prm.rbuf);
+       kfree(uac);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(g_audio_setup);
+
+void g_audio_cleanup(struct g_audio *g_audio)
+{
+       struct snd_uac_chip *uac;
+       struct snd_card *card;
+
+       if (!g_audio || !g_audio->uac)
+               return;
+
+       uac = g_audio->uac;
+       card = uac->card;
+       if (card)
+               snd_card_free(card);
+
+       kfree(uac->p_prm.ureq);
+       kfree(uac->c_prm.ureq);
+       kfree(uac->p_prm.rbuf);
+       kfree(uac->c_prm.rbuf);
+       kfree(uac);
+}
+EXPORT_SYMBOL_GPL(g_audio_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("USB gadget \"ALSA sound card\" utilities");
+MODULE_AUTHOR("Ruslan Bilovol");

drivers/usb/gadget/function/u_audio.h new file +95 -0

new file mode 100644
index 0000000..07e1378
@@ -0,0 +1,95 @@
+/*
+ * u_audio.h -- interface to USB gadget "ALSA sound card" utilities
+ *
+ * Copyright (C) 2016
+ * Author: Ruslan Bilovol <[email protected]>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __U_AUDIO_H
+#define __U_AUDIO_H
+
+#include <linux/usb/composite.h>
+
+struct uac_params {
+       /* playback */
+       int p_chmask;   /* channel mask */
+       int p_srate;    /* rate in Hz */
+       int p_ssize;    /* sample size */
+
+       /* capture */
+       int c_chmask;   /* channel mask */
+       int c_srate;    /* rate in Hz */
+       int c_ssize;    /* sample size */
+
+       int req_number; /* number of preallocated requests */
+};
+
+struct g_audio {
+       struct usb_function func;
+       struct usb_gadget *gadget;
+
+       struct usb_ep *in_ep;
+       struct usb_ep *out_ep;
+
+       /* Max packet size for all in_ep possible speeds */
+       unsigned int in_ep_maxpsize;
+       /* Max packet size for all out_ep possible speeds */
+       unsigned int out_ep_maxpsize;
+
+       /* The ALSA Sound Card it represents on the USB-Client side */
+       struct snd_uac_chip *uac;
+
+       struct uac_params params;
+};
+
+static inline struct g_audio *func_to_g_audio(struct usb_function *f)
+{
+       return container_of(f, struct g_audio, func);
+}
+
+static inline uint num_channels(uint chanmask)
+{
+       uint num = 0;
+
+       while (chanmask) {
+               num += (chanmask & 1);
+               chanmask >>= 1;
+       }
+
+       return num;
+}
+
+/*
+ * g_audio_setup - initialize one virtual ALSA sound card
+ * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize
+ * @pcm_name: the id string for a PCM instance of this sound card
+ * @card_name: name of this soundcard
+ *
+ * This sets up the single virtual ALSA sound card that may be exported by a
+ * gadget driver using this framework.
+ *
+ * Context: may sleep
+ *
+ * Returns zero on success, or a negative error on failure.
+ */
+int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
+                                       const char *card_name);
+void g_audio_cleanup(struct g_audio *g_audio);
+
+int u_audio_start_capture(struct g_audio *g_audio);
+void u_audio_stop_capture(struct g_audio *g_audio);
+int u_audio_start_playback(struct g_audio *g_audio);
+void u_audio_stop_playback(struct g_audio *g_audio);
+
+#endif /* __U_AUDIO_H */

drivers/usb/gadget/legacy/Kconfig +1 -1

index 0b36878..5344064 100644
@@ -56,6 +56,7 @@ config USB_AUDIO
        select SND_PCM
        select USB_F_UAC1 if GADGET_UAC1
        select USB_F_UAC2 if !GADGET_UAC1
+       select USB_U_AUDIO if USB_F_UAC2
        help
          This Gadget Audio driver is compatible with USB Audio Class
          specification 2.0. It implements 1 AudioControl interface,
--

1.9.1

Quoted 985 lines · Ruslan Bilovol

Abstract the peripheral side ALSA sound card code from the f_uac2 function into a component that can be called by various functions, so the various flavors can be split apart and selectively reused.

Visible changes:
- add uac_params structure to pass audio paramteres for g_audio_setup
- make ALSA sound card's name configurable
- add [in/out]_ep_maxpsize
- allocate snd_uac_chip structure during g_audio_setup
- add u_audio_[start/stop]_[capture/playback] functions

Signed-off-by Ruslan Bilovol <[email protected]>

---
 drivers/usb/gadget/Kconfig            |   4 +
 drivers/usb/gadget/function/Makefile  |   1 +
 drivers/usb/gadget/function/f_uac2.c  | 721 ++++------------------------------
 drivers/usb/gadget/function/u_audio.c | 661 +++++++++++++++++++++++++++++++
 drivers/usb/gadget/function/u_audio.h |  95 +++++
 drivers/usb/gadget/legacy/Kconfig     |   1 +
 6 files changed, 846 insertions(+), 637 deletions(-)
 create mode 100644 drivers/usb/gadget/function/u_audio.c
 create mode 100644 drivers/usb/gadget/function/u_audio.h

drivers/usb/gadget/Kconfig +4 -0

index c164d6b..2ba0ace 100644
@@ -158,6 +158,9 @@ config USB_U_SERIAL
 config USB_U_ETHER
        tristate
 
+config USB_U_AUDIO
+       tristate
+
 config USB_F_SERIAL
        tristate
 

@@ -381,6 +384,7 @@ config USB_CONFIGFS_F_UAC2
        depends on SND
        select USB_LIBCOMPOSITE
        select SND_PCM
+       select USB_U_AUDIO
        select USB_F_UAC2
        help
          This Audio function is compatible with USB Audio Class

drivers/usb/gadget/function/Makefile +1 -0

index cb8c225..b29f2ae 100644
@@ -32,6 +32,7 @@ usb_f_mass_storage-y          := f_mass_storage.o storage_common.o
 obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o
 usb_f_fs-y                     := f_fs.o
 obj-$(CONFIG_USB_F_FS)         += usb_f_fs.o
+obj-$(CONFIG_USB_U_AUDIO)      += u_audio.o
 usb_f_uac1-y                   := f_uac1.o u_uac1.o
 obj-$(CONFIG_USB_F_UAC1)       += usb_f_uac1.o
 usb_f_uac2-y                   := f_uac2.o

drivers/usb/gadget/function/f_uac2.c +82 -636

index d4565b5..059a14a 100644
@@ -15,10 +15,7 @@
 #include <linux/usb/audio-v2.h>
 #include <linux/module.h>
 
-#include <sound/core.h>
-#include <sound/pcm.h>
-#include <sound/pcm_params.h>
-
+#include "u_audio.h"
 #include "u_uac2.h"
 
 /*

@@ -50,455 +47,23 @@
 #define UNFLW_CTRL     8
 #define OVFLW_CTRL     10
 
-struct uac2_req {
-       struct uac2_rtd_params *pp; /* parent param */
-       struct usb_request *req;
-};
-
-struct uac2_rtd_params {
-       struct snd_uac2_chip *uac2; /* parent chip */
-       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;
-
-       spinlock_t lock;
-};
-
-struct snd_uac2_chip {
-       struct uac2_rtd_params p_prm;
-       struct uac2_rtd_params c_prm;
-
-       struct snd_card *card;
-       struct snd_pcm *pcm;
-
-       /* timekeeping for the playback endpoint */
-       unsigned int p_interval;
-       unsigned int p_residue;
-
-       /* pre-calculated values for playback iso completion */
-       unsigned int p_pktsize;
-       unsigned int p_pktsize_residue;
-       unsigned int p_framesize;
+struct f_uac2 {
+       struct g_audio g_audio;
+       u8 ac_intf, as_in_intf, as_out_intf;
+       u8 ac_alt, as_in_alt, as_out_alt;       /* needed for get_alt() */
 };
 
-#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 {
-       u8 ac_intf, ac_alt;
-       u8 as_out_intf, as_out_alt;
-       u8 as_in_intf, as_in_alt;
-
-       struct usb_ep *in_ep, *out_ep;
-       struct usb_function func;
-       struct usb_gadget *gadget;
-
-       /* The ALSA Sound Card it represents on the USB-Client side */
-       struct snd_uac2_chip uac2;
-};
-
-static inline
-struct audio_dev *func_to_agdev(struct usb_function *f)
+static inline struct f_uac2 *func_to_uac2(struct usb_function *f)
 {
-       return container_of(f, struct audio_dev, func);
+       return container_of(f, struct f_uac2, g_audio.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 f_uac2_opts *agdev_to_uac2_opts(struct audio_dev *agdev)
+struct f_uac2_opts *g_audio_to_uac2_opts(struct g_audio *agdev)
 {
        return container_of(agdev->func.fi, struct f_uac2_opts, func_inst);
 }
 
-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;
-       unsigned int hw_ptr;
-       bool update_alsa = false;
-       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->uac2;
-
-       /* i/f shutting down */
-       if (!prm->ep_enabled || req->status == -ESHUTDOWN)
-               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) {
-               /*
-                * For each IN packet, take the quotient of the current data
-                * rate and the endpoint's interval as the base packet size.
-                * If there is a residue from this division, add it to the
-                * residue accumulator.
-                */
-               req->length = uac2->p_pktsize;
-               uac2->p_residue += uac2->p_pktsize_residue;
-
-               /*
-                * Whenever there are more bytes in the accumulator than we
-                * need to add one more sample frame, increase this packet's
-                * size and decrease the accumulator.
-                */
-               if (uac2->p_residue / uac2->p_interval >= uac2->p_framesize) {
-                       req->length += uac2->p_framesize;
-                       uac2->p_residue -= uac2->p_framesize *
-                                          uac2->p_interval;
-               }
-
-               req->actual = req->length;
-       }
-
-       pending = prm->hw_ptr % prm->period_size;
-       pending += req->actual;
-       if (pending >= prm->period_size)
-               update_alsa = true;
-
-       hw_ptr = prm->hw_ptr;
-       prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
-
-       spin_unlock_irqrestore(&prm->lock, flags);
-
-       /* Pack USB load in ALSA ring buffer */
-       pending = prm->dma_bytes - hw_ptr;
-
-       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
-               if (unlikely(pending < req->actual)) {
-                       memcpy(req->buf, prm->dma_area + hw_ptr, pending);
-                       memcpy(req->buf + pending, prm->dma_area,
-                              req->actual - pending);
-               } else {
-                       memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);
-               }
-       } else {
-               if (unlikely(pending < req->actual)) {
-                       memcpy(prm->dma_area + hw_ptr, req->buf, pending);
-                       memcpy(prm->dma_area, req->buf + pending,
-                              req->actual - pending);
-               } else {
-                       memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);
-               }
-       }
-
-exit:
-       if (usb_ep_queue(ep, req, GFP_ATOMIC))
-               dev_err(uac2->card->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 f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
-       struct uac2_rtd_params *prm;
-       unsigned long flags;
-       int err = 0;
-
-       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
-               prm = &uac2->p_prm;
-       else
-               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 * uac2_opts->req_number);
-
-       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;
-       struct audio_dev *audio_dev;
-       struct f_uac2_opts *opts;
-       int p_ssize, c_ssize;
-       int p_srate, c_srate;
-       int p_chmask, c_chmask;
-
-       audio_dev = uac2_to_agdev(uac2);
-       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
-       p_ssize = opts->p_ssize;
-       c_ssize = opts->c_ssize;
-       p_srate = opts->p_srate;
-       c_srate = opts->c_srate;
-       p_chmask = opts->p_chmask;
-       c_chmask = opts->c_chmask;
-       uac2->p_residue = 0;
-
-       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;
-               switch (p_ssize) {
-               case 3:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-                       break;
-               case 4:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-                       break;
-               default:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-                       break;
-               }
-               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;
-               switch (c_ssize) {
-               case 3:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
-                       break;
-               case 4:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
-                       break;
-               default:
-                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
-                       break;
-               }
-               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 snd_uac2_probe(struct audio_dev *audio_dev)
-{
-       struct snd_uac2_chip *uac2 = &audio_dev->uac2;
-       struct snd_card *card;
-       struct snd_pcm *pcm;
-       struct f_uac2_opts *opts;
-       int err;
-       int p_chmask, c_chmask;
-
-       opts = container_of(audio_dev->func.fi, struct f_uac2_opts, func_inst);
-       p_chmask = opts->p_chmask;
-       c_chmask = opts->c_chmask;
-
-       /* Choose any slot, with no id */
-       err = snd_card_new(&audio_dev->gadget->dev,
-                       -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_Gadget");
-       strcpy(card->shortname, "UAC2_Gadget");
-       sprintf(card->longname, "UAC2_Gadget %i", card->dev->id);
-
-       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)
-               return 0;
-
-snd_fail:
-       snd_card_free(card);
-
-       uac2->pcm = NULL;
-       uac2->card = NULL;
-
-       return err;
-}
-
-static int snd_uac2_remove(struct audio_dev *audio_dev)
-{
-       struct snd_card *card = audio_dev->uac2.card;
-
-       if (card)
-               return snd_card_free(card);
-
-       return 0;
-}
-
-
 /* --------- USB Function Interface ------------- */
 
 enum {

@@ -886,32 +451,6 @@ struct cntrl_range_lay3 {
        __u32   dRES;
 } __packed;
 
-static inline void
-free_ep(struct uac2_rtd_params *prm, struct usb_ep *ep)
-{
-       struct snd_uac2_chip *uac2 = prm->uac2;
-       struct audio_dev *agdev = uac2_to_agdev(uac2);
-       struct f_uac2_opts *uac2_opts = agdev_to_uac2_opts(agdev);
-       int i;
-
-       if (!prm->ep_enabled)
-               return;
-
-       prm->ep_enabled = false;
-
-       for (i = 0; i < uac2_opts->req_number; 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->card->dev,
-                       "%s:%d Error!\n", __func__, __LINE__);
-}
-
 static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        struct usb_endpoint_descriptor *ep_desc,
        unsigned int factor, bool is_playback)

@@ -938,12 +477,11 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 static int
 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 f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
        struct usb_composite_dev *cdev = cfg->cdev;
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
-       struct uac2_rtd_params *prm;
        struct f_uac2_opts *uac2_opts;
        struct usb_string *us;
        int ret;

@@ -990,8 +528,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return ret;
        }
        std_ac_if_desc.bInterfaceNumber = ret;
-       agdev->ac_intf = ret;
-       agdev->ac_alt = 0;
+       uac2->ac_intf = ret;
+       uac2->ac_alt = 0;
 
        ret = usb_interface_id(cfg, fn);
        if (ret < 0) {

@@ -1000,8 +538,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        }
        std_as_out_if0_desc.bInterfaceNumber = ret;
        std_as_out_if1_desc.bInterfaceNumber = ret;
-       agdev->as_out_intf = ret;
-       agdev->as_out_alt = 0;
+       uac2->as_out_intf = ret;
+       uac2->as_out_alt = 0;
 
        ret = usb_interface_id(cfg, fn);
        if (ret < 0) {

@@ -1010,8 +548,8 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        }
        std_as_in_if0_desc.bInterfaceNumber = ret;
        std_as_in_if1_desc.bInterfaceNumber = ret;
-       agdev->as_in_intf = ret;
-       agdev->as_in_alt = 0;
+       uac2->as_in_intf = ret;
+       uac2->as_in_alt = 0;
 
        agdev->out_ep = usb_ep_autoconfig(gadget, &fs_epout_desc);
        if (!agdev->out_ep) {

@@ -1025,15 +563,17 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return ret;
        }
 
-       uac2->p_prm.uac2 = uac2;
-       uac2->c_prm.uac2 = uac2;
-
        /* Calculate wMaxPacketSize according to audio bandwidth */
        set_ep_max_packet_size(uac2_opts, &fs_epin_desc, 1000, true);
        set_ep_max_packet_size(uac2_opts, &fs_epout_desc, 1000, false);
        set_ep_max_packet_size(uac2_opts, &hs_epin_desc, 8000, true);
        set_ep_max_packet_size(uac2_opts, &hs_epout_desc, 8000, false);
 
+       agdev->in_ep_maxpsize = max(fs_epin_desc.wMaxPacketSize,
+                                       hs_epin_desc.wMaxPacketSize);
+       agdev->out_ep_maxpsize = max(fs_epout_desc.wMaxPacketSize,
+                                       hs_epout_desc.wMaxPacketSize);
+
        hs_epout_desc.bEndpointAddress = fs_epout_desc.bEndpointAddress;
        hs_epin_desc.bEndpointAddress = fs_epin_desc.bEndpointAddress;
 

@@ -1044,46 +584,18 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 
        agdev->gadget = gadget;
 
-       prm = &agdev->uac2.c_prm;
-       prm->max_psize = hs_epout_desc.wMaxPacketSize;
-       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
-                       GFP_KERNEL);
-       if (!prm->ureq) {
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
-       if (!prm->rbuf) {
-               prm->max_psize = 0;
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-
-       prm = &agdev->uac2.p_prm;
-       prm->max_psize = hs_epin_desc.wMaxPacketSize;
-       prm->ureq = kcalloc(uac2_opts->req_number, sizeof(struct uac2_req),
-                       GFP_KERNEL);
-       if (!prm->ureq) {
-               ret = -ENOMEM;
-               goto err_free_descs;
-       }
-       prm->rbuf = kcalloc(uac2_opts->req_number, prm->max_psize, GFP_KERNEL);
-       if (!prm->rbuf) {
-               prm->max_psize = 0;
-               ret = -ENOMEM;
-               goto err_no_memory;
-       }
-
-       ret = snd_uac2_probe(agdev);
+       agdev->params.p_chmask = uac2_opts->p_chmask;
+       agdev->params.p_srate = uac2_opts->p_srate;
+       agdev->params.p_ssize = uac2_opts->p_ssize;
+       agdev->params.c_chmask = uac2_opts->c_chmask;
+       agdev->params.c_srate = uac2_opts->c_srate;
+       agdev->params.c_ssize = uac2_opts->c_ssize;
+       agdev->params.req_number = uac2_opts->req_number;
+       ret = g_audio_setup(agdev, "UAC2 PCM", "UAC2_Gadget");
        if (ret)
-               goto err_no_memory;
+               goto err_free_descs;
        return 0;
 
-err_no_memory:
-       kfree(agdev->uac2.p_prm.ureq);
-       kfree(agdev->uac2.c_prm.ureq);
-       kfree(agdev->uac2.p_prm.rbuf);
-       kfree(agdev->uac2.c_prm.rbuf);
 err_free_descs:
        usb_free_all_descriptors(fn);
        agdev->gadget = NULL;

@@ -1094,15 +606,10 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 f_uac2_opts *opts = agdev_to_uac2_opts(agdev);
-       struct snd_uac2_chip *uac2 = &agdev->uac2;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
        struct usb_gadget *gadget = cdev->gadget;
        struct device *dev = &gadget->dev;
-       struct usb_request *req;
-       struct usb_ep *ep;
-       struct uac2_rtd_params *prm;
-       int req_len, i;
+       int ret = 0;
 
        /* No i/f has more than 2 alt settings */
        if (alt > 1) {

@@ -1110,7 +617,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return -EINVAL;
        }
 
-       if (intf == agdev->ac_intf) {
+       if (intf == uac2->ac_intf) {
                /* Control I/f has only 1 AltSetting - 0 */
                if (alt) {
                        dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

@@ -1119,92 +626,40 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
                return 0;
        }
 
-       if (intf == agdev->as_out_intf) {
-               ep = agdev->out_ep;
-               prm = &uac2->c_prm;
-               config_ep_by_speed(gadget, fn, ep);
-               agdev->as_out_alt = alt;
-               req_len = prm->max_psize;
-       } else if (intf == agdev->as_in_intf) {
-               unsigned int factor, rate;
-               struct usb_endpoint_descriptor *ep_desc;
-
-               ep = agdev->in_ep;
-               prm = &uac2->p_prm;
-               config_ep_by_speed(gadget, fn, ep);
-               agdev->as_in_alt = alt;
-
-               /* pre-calculate the playback endpoint's interval */
-               if (gadget->speed == USB_SPEED_FULL) {
-                       ep_desc = &fs_epin_desc;
-                       factor = 1000;
-               } else {
-                       ep_desc = &hs_epin_desc;
-                       factor = 8000;
-               }
-
-               /* pre-compute some values for iso_complete() */
-               uac2->p_framesize = opts->p_ssize *
-                                   num_channels(opts->p_chmask);
-               rate = opts->p_srate * uac2->p_framesize;
-               uac2->p_interval = factor / (1 << (ep_desc->bInterval - 1));
-               uac2->p_pktsize = min_t(unsigned int, rate / uac2->p_interval,
-                                       prm->max_psize);
+       if (intf == uac2->as_out_intf) {
+               uac2->as_out_alt = alt;
 
-               if (uac2->p_pktsize < prm->max_psize)
-                       uac2->p_pktsize_residue = rate % uac2->p_interval;
+               if (alt)
+                       ret = u_audio_start_capture(&uac2->g_audio);
                else
-                       uac2->p_pktsize_residue = 0;
+                       u_audio_stop_capture(&uac2->g_audio);
+       } else if (intf == uac2->as_in_intf) {
+               uac2->as_in_alt = alt;
 
-               req_len = uac2->p_pktsize;
-               uac2->p_residue = 0;
+               if (alt)
+                       ret = u_audio_start_playback(&uac2->g_audio);
+               else
+                       u_audio_stop_playback(&uac2->g_audio);
        } else {
                dev_err(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 < opts->req_number; i++) {
-               if (!prm->ureq[i].req) {
-                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
-                       if (req == NULL)
-                               return -ENOMEM;
-
-                       prm->ureq[i].req = req;
-                       prm->ureq[i].pp = prm;
-
-                       req->zero = 0;
-                       req->context = &prm->ureq[i];
-                       req->length = req_len;
-                       req->complete = agdev_iso_complete;
-                       req->buf = prm->rbuf + i * prm->max_psize;
-               }
-
-               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
-                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
-       }
-
-       return 0;
+       return ret;
 }
 
 static int
 afunc_get_alt(struct usb_function *fn, unsigned intf)
 {
-       struct audio_dev *agdev = func_to_agdev(fn);
-
-       if (intf == agdev->ac_intf)
-               return agdev->ac_alt;
-       else if (intf == agdev->as_out_intf)
-               return agdev->as_out_alt;
-       else if (intf == agdev->as_in_intf)
-               return agdev->as_in_alt;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
+
+       if (intf == uac2->ac_intf)
+               return uac2->ac_alt;
+       else if (intf == uac2->as_out_intf)
+               return uac2->as_out_alt;
+       else if (intf == uac2->as_in_intf)
+               return uac2->as_in_alt;
        else
                dev_err(&agdev->gadget->dev,
                        "%s:%d Invalid Interface %d!\n",

@@ -1216,21 +671,19 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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);
-       agdev->as_in_alt = 0;
+       struct f_uac2 *uac2 = func_to_uac2(fn);
 
-       free_ep(&uac2->c_prm, agdev->out_ep);
-       agdev->as_out_alt = 0;
+       uac2->as_in_alt = 0;
+       uac2->as_out_alt = 0;
+       u_audio_stop_capture(&uac2->g_audio);
+       u_audio_stop_playback(&uac2->g_audio);
 }
 
 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 g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts;
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);

@@ -1240,7 +693,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        int value = -EOPNOTSUPP;
        int p_srate, c_srate;
 
-       opts = agdev_to_uac2_opts(agdev);
+       opts = g_audio_to_uac2_opts(agdev);
        p_srate = opts->p_srate;
        c_srate = opts->c_srate;
 

@@ -1271,7 +724,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 g_audio *agdev = func_to_g_audio(fn);
        struct f_uac2_opts *opts;
        u16 w_length = le16_to_cpu(cr->wLength);
        u16 w_index = le16_to_cpu(cr->wIndex);

@@ -1282,7 +735,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
        int value = -EOPNOTSUPP;
        int p_srate, c_srate;
 
-       opts = agdev_to_uac2_opts(agdev);
+       opts = g_audio_to_uac2_opts(agdev);
        p_srate = opts->p_srate;
        c_srate = opts->c_srate;
 

@@ -1336,11 +789,12 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 static int
 setup_rq_inf(struct usb_function *fn, const struct usb_ctrlrequest *cr)
 {
-       struct audio_dev *agdev = func_to_agdev(fn);
+       struct f_uac2 *uac2 = func_to_uac2(fn);
+       struct g_audio *agdev = func_to_g_audio(fn);
        u16 w_index = le16_to_cpu(cr->wIndex);
        u8 intf = w_index & 0xff;
 
-       if (intf != agdev->ac_intf) {
+       if (intf != uac2->ac_intf) {
                dev_err(&agdev->gadget->dev,
                        "%s:%d Error!\n", __func__, __LINE__);
                return -EOPNOTSUPP;

@@ -1358,7 +812,7 @@ static void set_ep_max_packet_size(const struct f_uac2_opts *uac2_opts,
 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 g_audio *agdev = func_to_g_audio(fn);
        struct usb_request *req = cdev->req;
        u16 w_length = le16_to_cpu(cr->wLength);
        int value = -EOPNOTSUPP;

@@ -1504,10 +958,10 @@ static struct usb_function_instance *afunc_alloc_inst(void)
 
 static void afunc_free(struct usb_function *f)
 {
-       struct audio_dev *agdev;
+       struct g_audio *agdev;
        struct f_uac2_opts *opts;
 
-       agdev = func_to_agdev(f);
+       agdev = func_to_g_audio(f);
        opts = container_of(f->fi, struct f_uac2_opts, func_inst);
        kfree(agdev);
        mutex_lock(&opts->lock);

@@ -1517,17 +971,9 @@ static void afunc_free(struct usb_function *f)
 
 static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
 {
-       struct audio_dev *agdev = func_to_agdev(f);
-       struct uac2_rtd_params *prm;
-
-       snd_uac2_remove(agdev);
-
-       prm = &agdev->uac2.p_prm;
-       kfree(prm->rbuf);
+       struct g_audio *agdev = func_to_g_audio(f);
 
-       prm = &agdev->uac2.c_prm;
-       kfree(prm->rbuf);
-       kfree(prm->ureq);
+       g_audio_cleanup(agdev);
        usb_free_all_descriptors(f);
 
        agdev->gadget = NULL;

@@ -1535,11 +981,11 @@ static void afunc_unbind(struct usb_configuration *c, struct usb_function *f)
 
 static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
 {
-       struct audio_dev *agdev;
+       struct f_uac2   *uac2;
        struct f_uac2_opts *opts;
 
-       agdev = kzalloc(sizeof(*agdev), GFP_KERNEL);
-       if (agdev == NULL)
+       uac2 = kzalloc(sizeof(*uac2), GFP_KERNEL);
+       if (uac2 == NULL)
                return ERR_PTR(-ENOMEM);
 
        opts = container_of(fi, struct f_uac2_opts, func_inst);

@@ -1547,19 +993,20 @@ static struct usb_function *afunc_alloc(struct usb_function_instance *fi)
        ++opts->refcnt;
        mutex_unlock(&opts->lock);
 
-       agdev->func.name = "uac2_func";
-       agdev->func.bind = afunc_bind;
-       agdev->func.unbind = afunc_unbind;
-       agdev->func.set_alt = afunc_set_alt;
-       agdev->func.get_alt = afunc_get_alt;
-       agdev->func.disable = afunc_disable;
-       agdev->func.setup = afunc_setup;
-       agdev->func.free_func = afunc_free;
+       uac2->g_audio.func.name = "uac2_func";
+       uac2->g_audio.func.bind = afunc_bind;
+       uac2->g_audio.func.unbind = afunc_unbind;
+       uac2->g_audio.func.set_alt = afunc_set_alt;
+       uac2->g_audio.func.get_alt = afunc_get_alt;
+       uac2->g_audio.func.disable = afunc_disable;
+       uac2->g_audio.func.setup = afunc_setup;
+       uac2->g_audio.func.free_func = afunc_free;

drivers/usb/gadget/function/f_uac2.c static struct usb_function *afunc_alloc(struct usb_function_instance *fi) · line 1012

Quoted 10 lines

drivers/usb/gadget/function/f_uac2.c +2 -1

 
-       return &agdev->func;
+       return &uac2->g_audio.func;
 }
 
 DECLARE_USB_FUNCTION_INIT(uac2, afunc_alloc_inst, afunc_alloc);
 MODULE_LICENSE("GPL");
 MODULE_AUTHOR("Yadwinder Singh");
 MODULE_AUTHOR("Jaswinder Singh");
+MODULE_AUTHOR("Ruslan Bilovol");

drivers/usb/gadget/function/f_uac2.c | 721 ++++------------------------------

Basically you move out ALSA sound card implementation and %s/agdev/uac2/ I am not sure churn warrants a MODULE_AUTHOR. People have made far more important contribution to the UAC2,

Quoted 16 lines

drivers/usb/gadget/function/u_audio.c new file +8 -0

new file mode 100644
index 0000000..8ee65b8
@@ -0,0 +1,661 @@
+/*
+ * u_audio.c -- interface to USB gadget "ALSA sound card" utilities
+ *
+ * Copyright (C) 2016
+ * Author: Ruslan Bilovol <[email protected]>
+ *
+ * Based on f_uac2.c which is:
+ *    Copyright (C) 2011

drivers/usb/gadget/function/u_audio.c line 11

Quoted 3 lines

drivers/usb/gadget/function/u_audio.c new file +3 -0

+ *    Yadwinder Singh ([email protected])
+ *    Jaswinder Singh ([email protected])
+ *

Again this is not "based on", rather where you paste the code you cut from f_uac2.c
Of course you also pad it with minor changes to make it useful to your uac1 code. I am not happy with losing copyright on the sound card implementation for the UAC drivers.

Quoted 767 lines

drivers/usb/gadget/function/u_audio.c new file +650 -0

+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "u_audio.h"
+
+#define BUFF_SIZE_MAX  (PAGE_SIZE * 16)
+#define PRD_SIZE_MAX   PAGE_SIZE
+#define MIN_PERIODS    4
+
+struct uac_req {
+       struct uac_rtd_params *pp; /* parent param */
+       struct usb_request *req;
+};
+
+/* Runtime data params for one stream */
+struct uac_rtd_params {
+       struct snd_uac_chip *uac; /* parent chip */
+       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;     /* MaxPacketSize of endpoint */
+       struct uac_req *ureq;
+
+       spinlock_t lock;
+};
+
+struct snd_uac_chip {
+       struct g_audio *audio_dev;
+
+       struct uac_rtd_params p_prm;
+       struct uac_rtd_params c_prm;
+
+       struct snd_card *card;
+       struct snd_pcm *pcm;
+
+       /* timekeeping for the playback endpoint */
+       unsigned int p_interval;
+       unsigned int p_residue;
+
+       /* pre-calculated values for playback iso completion */
+       unsigned int p_pktsize;
+       unsigned int p_pktsize_residue;
+       unsigned int p_framesize;
+};
+
+static struct snd_pcm_hardware uac_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,
+};
+
+static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
+{
+       unsigned pending;
+       unsigned long flags;
+       unsigned int hw_ptr;
+       bool update_alsa = false;
+       int status = req->status;
+       struct uac_req *ur = req->context;
+       struct snd_pcm_substream *substream;
+       struct uac_rtd_params *prm = ur->pp;
+       struct snd_uac_chip *uac = prm->uac;
+
+       /* i/f shutting down */
+       if (!prm->ep_enabled || req->status == -ESHUTDOWN)
+               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) {
+               /*
+                * For each IN packet, take the quotient of the current data
+                * rate and the endpoint's interval as the base packet size.
+                * If there is a residue from this division, add it to the
+                * residue accumulator.
+                */
+               req->length = uac->p_pktsize;
+               uac->p_residue += uac->p_pktsize_residue;
+
+               /*
+                * Whenever there are more bytes in the accumulator than we
+                * need to add one more sample frame, increase this packet's
+                * size and decrease the accumulator.
+                */
+               if (uac->p_residue / uac->p_interval >= uac->p_framesize) {
+                       req->length += uac->p_framesize;
+                       uac->p_residue -= uac->p_framesize *
+                                          uac->p_interval;
+               }
+
+               req->actual = req->length;
+       }
+
+       pending = prm->hw_ptr % prm->period_size;
+       pending += req->actual;
+       if (pending >= prm->period_size)
+               update_alsa = true;
+
+       hw_ptr = prm->hw_ptr;
+       prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
+
+       spin_unlock_irqrestore(&prm->lock, flags);
+
+       /* Pack USB load in ALSA ring buffer */
+       pending = prm->dma_bytes - hw_ptr;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+               if (unlikely(pending < req->actual)) {
+                       memcpy(req->buf, prm->dma_area + hw_ptr, pending);
+                       memcpy(req->buf + pending, prm->dma_area,
+                              req->actual - pending);
+               } else {
+                       memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);
+               }
+       } else {
+               if (unlikely(pending < req->actual)) {
+                       memcpy(prm->dma_area + hw_ptr, req->buf, pending);
+                       memcpy(prm->dma_area, req->buf + pending,
+                              req->actual - pending);
+               } else {
+                       memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);
+               }
+       }
+
+exit:
+       if (usb_ep_queue(ep, req, GFP_ATOMIC))
+               dev_err(uac->card->dev, "%d Error!\n", __LINE__);
+
+       if (update_alsa)
+               snd_pcm_period_elapsed(substream);
+}
+
+static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       unsigned long flags;
+       int err = 0;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->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 * params->req_number);
+
+       return err;
+}
+
+static snd_pcm_uframes_t uac_pcm_pointer(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->c_prm;
+
+       return bytes_to_frames(substream->runtime, prm->hw_ptr);
+}
+
+static int uac_pcm_hw_params(struct snd_pcm_substream *substream,
+                              struct snd_pcm_hw_params *hw_params)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+       int err;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->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 uac_pcm_hw_free(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct uac_rtd_params *prm;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+               prm = &uac->p_prm;
+       else
+               prm = &uac->c_prm;
+
+       prm->dma_area = NULL;
+       prm->dma_bytes = 0;
+       prm->period_size = 0;
+
+       return snd_pcm_lib_free_pages(substream);
+}
+
+static int uac_pcm_open(struct snd_pcm_substream *substream)
+{
+       struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);
+       struct snd_pcm_runtime *runtime = substream->runtime;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       int p_ssize, c_ssize;
+       int p_srate, c_srate;
+       int p_chmask, c_chmask;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+       p_ssize = params->p_ssize;
+       c_ssize = params->c_ssize;
+       p_srate = params->p_srate;
+       c_srate = params->c_srate;
+       p_chmask = params->p_chmask;
+       c_chmask = params->c_chmask;
+       uac->p_residue = 0;
+
+       runtime->hw = uac_pcm_hardware;
+
+       if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
+               spin_lock_init(&uac->p_prm.lock);
+               runtime->hw.rate_min = p_srate;
+               switch (p_ssize) {
+               case 3:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
+                       break;
+               case 4:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
+                       break;
+               default:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
+                       break;
+               }
+               runtime->hw.channels_min = num_channels(p_chmask);
+               runtime->hw.period_bytes_min = 2 * uac->p_prm.max_psize
+                                               / runtime->hw.periods_min;
+       } else {
+               spin_lock_init(&uac->c_prm.lock);
+               runtime->hw.rate_min = c_srate;
+               switch (c_ssize) {
+               case 3:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;
+                       break;
+               case 4:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;
+                       break;
+               default:
+                       runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;
+                       break;
+               }
+               runtime->hw.channels_min = num_channels(c_chmask);
+               runtime->hw.period_bytes_min = 2 * uac->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 uac_pcm_null(struct snd_pcm_substream *substream)
+{
+       return 0;
+}
+
+static struct snd_pcm_ops uac_pcm_ops = {
+       .open = uac_pcm_open,
+       .close = uac_pcm_null,
+       .ioctl = snd_pcm_lib_ioctl,
+       .hw_params = uac_pcm_hw_params,
+       .hw_free = uac_pcm_hw_free,
+       .trigger = uac_pcm_trigger,
+       .pointer = uac_pcm_pointer,
+       .prepare = uac_pcm_null,
+};
+
+static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
+{
+       struct snd_uac_chip *uac = prm->uac;
+       struct g_audio *audio_dev;
+       struct uac_params *params;
+       int i;
+
+       if (!prm->ep_enabled)
+               return;
+
+       prm->ep_enabled = false;
+
+       audio_dev = uac->audio_dev;
+       params = &audio_dev->params;
+
+       for (i = 0; i < params->req_number; 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(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);
+}
+
+
+int u_audio_start_capture(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+       struct usb_gadget *gadget = audio_dev->gadget;
+       struct device *dev = &gadget->dev;
+       struct usb_request *req;
+       struct usb_ep *ep;
+       struct uac_rtd_params *prm;
+       struct uac_params *params = &audio_dev->params;
+       int req_len, i;
+
+       ep = audio_dev->out_ep;
+       prm = &uac->c_prm;
+       config_ep_by_speed(gadget, &audio_dev->func, ep);
+       req_len = prm->max_psize;
+
+       prm->ep_enabled = true;
+       usb_ep_enable(ep);
+
+       for (i = 0; i < params->req_number; i++) {
+               if (!prm->ureq[i].req) {
+                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+                       if (req == NULL)
+                               return -ENOMEM;
+
+                       prm->ureq[i].req = req;
+                       prm->ureq[i].pp = prm;
+
+                       req->zero = 0;
+                       req->context = &prm->ureq[i];
+                       req->length = req_len;
+                       req->complete = u_audio_iso_complete;
+                       req->buf = prm->rbuf + i * prm->max_psize;
+               }
+
+               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(u_audio_start_capture);
+
+void u_audio_stop_capture(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+
+       free_ep(&uac->c_prm, audio_dev->out_ep);
+}
+EXPORT_SYMBOL_GPL(u_audio_stop_capture);
+
+int u_audio_start_playback(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+       struct usb_gadget *gadget = audio_dev->gadget;
+       struct device *dev = &gadget->dev;
+       struct usb_request *req;
+       struct usb_ep *ep;
+       struct uac_rtd_params *prm;
+       struct uac_params *params = &audio_dev->params;
+       unsigned int factor, rate;
+       const struct usb_endpoint_descriptor *ep_desc;
+       int req_len, i;
+
+       ep = audio_dev->in_ep;
+       prm = &uac->p_prm;
+       config_ep_by_speed(gadget, &audio_dev->func, ep);
+
+       ep_desc = ep->desc;
+
+       /* pre-calculate the playback endpoint's interval */
+       if (gadget->speed == USB_SPEED_FULL)
+               factor = 1000;
+       else
+               factor = 8000;
+
+       /* pre-compute some values for iso_complete() */
+       uac->p_framesize = params->p_ssize *
+                           num_channels(params->p_chmask);
+       rate = params->p_srate * uac->p_framesize;
+       uac->p_interval = factor / (1 << (ep_desc->bInterval - 1));
+       uac->p_pktsize = min_t(unsigned int, rate / uac->p_interval,
+                               prm->max_psize);
+
+       if (uac->p_pktsize < prm->max_psize)
+               uac->p_pktsize_residue = rate % uac->p_interval;
+       else
+               uac->p_pktsize_residue = 0;
+
+       req_len = uac->p_pktsize;
+       uac->p_residue = 0;
+
+       prm->ep_enabled = true;
+       usb_ep_enable(ep);
+
+       for (i = 0; i < params->req_number; i++) {
+               if (!prm->ureq[i].req) {
+                       req = usb_ep_alloc_request(ep, GFP_ATOMIC);
+                       if (req == NULL)
+                               return -ENOMEM;
+
+                       prm->ureq[i].req = req;
+                       prm->ureq[i].pp = prm;
+
+                       req->zero = 0;
+                       req->context = &prm->ureq[i];
+                       req->length = req_len;
+                       req->complete = u_audio_iso_complete;
+                       req->buf = prm->rbuf + i * prm->max_psize;
+               }
+
+               if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))
+                       dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);
+       }
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(u_audio_start_playback);
+
+void u_audio_stop_playback(struct g_audio *audio_dev)
+{
+       struct snd_uac_chip *uac = audio_dev->uac;
+
+       free_ep(&uac->p_prm, audio_dev->in_ep);
+}
+EXPORT_SYMBOL_GPL(u_audio_stop_playback);
+
+int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
+                                       const char *card_name)
+{
+       struct snd_uac_chip *uac;
+       struct snd_card *card;
+       struct snd_pcm *pcm;
+       struct uac_params *params;
+       int p_chmask, c_chmask;
+       int err;
+
+       if (!g_audio)
+               return -EINVAL;
+
+       uac = kzalloc(sizeof(*uac), GFP_KERNEL);
+       if (!uac)
+               return -ENOMEM;
+       g_audio->uac = uac;
+       uac->audio_dev = g_audio;
+
+       params = &g_audio->params;
+       p_chmask = params->p_chmask;
+       c_chmask = params->c_chmask;
+
+       if (c_chmask) {
+               struct uac_rtd_params *prm = &uac->c_prm;
+
+               uac->c_prm.uac = uac;
+               prm->max_psize = g_audio->out_ep_maxpsize;
+
+               prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
+                               GFP_KERNEL);
+               if (!prm->ureq) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+
+               prm->rbuf = kcalloc(params->req_number, prm->max_psize,
+                               GFP_KERNEL);
+               if (!prm->rbuf) {
+                       prm->max_psize = 0;
+                       err = -ENOMEM;
+                       goto fail;
+               }
+       }
+
+       if (p_chmask) {
+               struct uac_rtd_params *prm = &uac->p_prm;
+
+               uac->p_prm.uac = uac;
+               prm->max_psize = g_audio->in_ep_maxpsize;
+
+               prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),
+                               GFP_KERNEL);
+               if (!prm->ureq) {
+                       err = -ENOMEM;
+                       goto fail;
+               }
+
+               prm->rbuf = kcalloc(params->req_number, prm->max_psize,
+                               GFP_KERNEL);
+               if (!prm->rbuf) {
+                       prm->max_psize = 0;
+                       err = -ENOMEM;
+                       goto fail;
+               }
+       }
+
+       /* Choose any slot, with no id */
+       err = snd_card_new(&g_audio->gadget->dev,
+                       -1, NULL, THIS_MODULE, 0, &card);
+       if (err < 0)
+               goto fail;
+
+       uac->card = card;
+
+       /*
+        * Create first PCM device
+        * Create a substream only for non-zero channel streams
+        */
+       err = snd_pcm_new(uac->card, pcm_name, 0,
+                              p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);
+       if (err < 0)
+               goto snd_fail;
+
+       strcpy(pcm->name, pcm_name);
+       pcm->private_data = uac;
+       uac->pcm = pcm;
+
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac_pcm_ops);
+       snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac_pcm_ops);
+
+       strcpy(card->driver, card_name);
+       strcpy(card->shortname, card_name);
+       sprintf(card->longname, "%s %i", card_name, card->dev->id);
+
+       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)
+               return 0;
+
+snd_fail:
+       snd_card_free(card);
+fail:
+       kfree(uac->p_prm.ureq);
+       kfree(uac->c_prm.ureq);
+       kfree(uac->p_prm.rbuf);
+       kfree(uac->c_prm.rbuf);
+       kfree(uac);
+
+       return err;
+}
+EXPORT_SYMBOL_GPL(g_audio_setup);
+
+void g_audio_cleanup(struct g_audio *g_audio)
+{
+       struct snd_uac_chip *uac;
+       struct snd_card *card;
+
+       if (!g_audio || !g_audio->uac)
+               return;
+
+       uac = g_audio->uac;
+       card = uac->card;
+       if (card)
+               snd_card_free(card);
+
+       kfree(uac->p_prm.ureq);
+       kfree(uac->c_prm.ureq);
+       kfree(uac->p_prm.rbuf);
+       kfree(uac->c_prm.rbuf);
+       kfree(uac);
+}
+EXPORT_SYMBOL_GPL(g_audio_cleanup);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("USB gadget \"ALSA sound card\" utilities");
+MODULE_AUTHOR("Ruslan Bilovol");

drivers/usb/gadget/function/u_audio.h new file +95 -0

new file mode 100644
index 0000000..07e1378
@@ -0,0 +1,95 @@
+/*
+ * u_audio.h -- interface to USB gadget "ALSA sound card" utilities
+ *
+ * Copyright (C) 2016
+ * Author: Ruslan Bilovol <[email protected]>
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __U_AUDIO_H
+#define __U_AUDIO_H
+
+#include <linux/usb/composite.h>
+
+struct uac_params {
+       /* playback */
+       int p_chmask;   /* channel mask */
+       int p_srate;    /* rate in Hz */
+       int p_ssize;    /* sample size */
+
+       /* capture */
+       int c_chmask;   /* channel mask */
+       int c_srate;    /* rate in Hz */
+       int c_ssize;    /* sample size */
+
+       int req_number; /* number of preallocated requests */
+};
+
+struct g_audio {
+       struct usb_function func;
+       struct usb_gadget *gadget;
+
+       struct usb_ep *in_ep;
+       struct usb_ep *out_ep;
+
+       /* Max packet size for all in_ep possible speeds */
+       unsigned int in_ep_maxpsize;
+       /* Max packet size for all out_ep possible speeds */
+       unsigned int out_ep_maxpsize;
+
+       /* The ALSA Sound Card it represents on the USB-Client side */
+       struct snd_uac_chip *uac;
+
+       struct uac_params params;
+};
+
+static inline struct g_audio *func_to_g_audio(struct usb_function *f)
+{
+       return container_of(f, struct g_audio, func);
+}
+
+static inline uint num_channels(uint chanmask)
+{
+       uint num = 0;
+
+       while (chanmask) {
+               num += (chanmask & 1);
+               chanmask >>= 1;
+       }
+
+       return num;
+}
+
+/*
+ * g_audio_setup - initialize one virtual ALSA sound card
+ * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize
+ * @pcm_name: the id string for a PCM instance of this sound card
+ * @card_name: name of this soundcard
+ *
+ * This sets up the single virtual ALSA sound card that may be exported by a
+ * gadget driver using this framework.
+ *
+ * Context: may sleep
+ *
+ * Returns zero on success, or a negative error on failure.
+ */
+int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
+                                       const char *card_name);
+void g_audio_cleanup(struct g_audio *g_audio);
+
+int u_audio_start_capture(struct g_audio *g_audio);
+void u_audio_stop_capture(struct g_audio *g_audio);
+int u_audio_start_playback(struct g_audio *g_audio);
+void u_audio_stop_playback(struct g_audio *g_audio);
+
+#endif /* __U_AUDIO_H */

drivers/usb/gadget/legacy/Kconfig +1 -1

index 0b36878..5344064 100644
@@ -56,6 +56,7 @@ config USB_AUDIO
        select SND_PCM
        select USB_F_UAC1 if GADGET_UAC1
        select USB_F_UAC2 if !GADGET_UAC1
+       select USB_U_AUDIO if USB_F_UAC2
        help
          This Gadget Audio driver is compatible with USB Audio Class
          specification 2.0. It implements 1 AudioControl interface,
--

1.9.1