From db3262ee89a58d0460ce84a0f231721207cef5a4 Mon Sep 17 00:00:00 2001 From: Mike Lockwood Date: Fri, 11 May 2012 09:01:08 -0700 Subject: [PATCH] USB: gadget: f_audio_source: New gadget driver for audio output This driver presents a standard USB audio class interface to the host and an ALSA PCM device to userspace Change-Id: If16b14a5ff27045f9cb2daaf1ae9195c5eeab7d0 Signed-off-by: Mike Lockwood --- drivers/usb/gadget/f_audio_source.c | 828 ++++++++++++++++++++++++++++ 1 file changed, 828 insertions(+) create mode 100644 drivers/usb/gadget/f_audio_source.c diff --git a/drivers/usb/gadget/f_audio_source.c b/drivers/usb/gadget/f_audio_source.c new file mode 100644 index 000000000000..c757409edf94 --- /dev/null +++ b/drivers/usb/gadget/f_audio_source.c @@ -0,0 +1,828 @@ +/* + * Gadget Function Driver for USB audio source device + * + * Copyright (C) 2012 Google, Inc. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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 +#include +#include +#include +#include +#include + +#define SAMPLE_RATE 44100 +#define FRAMES_PER_MSEC (SAMPLE_RATE / 1000) + +#define IN_EP_MAX_PACKET_SIZE 384 + +/* Number of requests to allocate */ +#define IN_EP_REQ_COUNT 4 + +#define AUDIO_AC_INTERFACE 0 +#define AUDIO_AS_INTERFACE 1 +#define AUDIO_NUM_INTERFACES 2 + +/* B.3.1 Standard AC Interface Descriptor */ +static struct usb_interface_descriptor ac_interface_desc = { + .bLength = USB_DT_INTERFACE_SIZE, + .bDescriptorType = USB_DT_INTERFACE, + .bNumEndpoints = 0, + .bInterfaceClass = USB_CLASS_AUDIO, + .bInterfaceSubClass = USB_SUBCLASS_AUDIOCONTROL, +}; + +DECLARE_UAC_AC_HEADER_DESCRIPTOR(2); + +#define UAC_DT_AC_HEADER_LENGTH UAC_DT_AC_HEADER_SIZE(AUDIO_NUM_INTERFACES) +/* 1 input terminal, 1 output terminal and 1 feature unit */ +#define UAC_DT_TOTAL_LENGTH (UAC_DT_AC_HEADER_LENGTH \ + + UAC_DT_INPUT_TERMINAL_SIZE + UAC_DT_OUTPUT_TERMINAL_SIZE \ + + UAC_DT_FEATURE_UNIT_SIZE(0)) +/* B.3.2 Class-Specific AC Interface Descriptor */ +static struct uac1_ac_header_descriptor_2 ac_header_desc = { + .bLength = UAC_DT_AC_HEADER_LENGTH, + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_HEADER, + .bcdADC = __constant_cpu_to_le16(0x0100), + .wTotalLength = __constant_cpu_to_le16(UAC_DT_TOTAL_LENGTH), + .bInCollection = AUDIO_NUM_INTERFACES, + .baInterfaceNr = { + [0] = AUDIO_AC_INTERFACE, + [1] = AUDIO_AS_INTERFACE, + } +}; + +#define INPUT_TERMINAL_ID 1 +static struct uac_input_terminal_descriptor input_terminal_desc = { + .bLength = UAC_DT_INPUT_TERMINAL_SIZE, + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_INPUT_TERMINAL, + .bTerminalID = INPUT_TERMINAL_ID, + .wTerminalType = UAC_INPUT_TERMINAL_MICROPHONE, + .bAssocTerminal = 0, + .wChannelConfig = 0x3, +}; + +DECLARE_UAC_FEATURE_UNIT_DESCRIPTOR(0); + +#define FEATURE_UNIT_ID 2 +static struct uac_feature_unit_descriptor_0 feature_unit_desc = { + .bLength = UAC_DT_FEATURE_UNIT_SIZE(0), + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_FEATURE_UNIT, + .bUnitID = FEATURE_UNIT_ID, + .bSourceID = INPUT_TERMINAL_ID, + .bControlSize = 2, +}; + +#define OUTPUT_TERMINAL_ID 3 +static struct uac1_output_terminal_descriptor output_terminal_desc = { + .bLength = UAC_DT_OUTPUT_TERMINAL_SIZE, + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_OUTPUT_TERMINAL, + .bTerminalID = OUTPUT_TERMINAL_ID, + .wTerminalType = UAC_TERMINAL_STREAMING, + .bAssocTerminal = FEATURE_UNIT_ID, + .bSourceID = FEATURE_UNIT_ID, +}; + +/* B.4.1 Standard AS Interface Descriptor */ +static struct usb_interface_descriptor as_interface_alt_0_desc = { + .bLength = USB_DT_INTERFACE_SIZE, + .bDescriptorType = USB_DT_INTERFACE, + .bAlternateSetting = 0, + .bNumEndpoints = 0, + .bInterfaceClass = USB_CLASS_AUDIO, + .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING, +}; + +static struct usb_interface_descriptor as_interface_alt_1_desc = { + .bLength = USB_DT_INTERFACE_SIZE, + .bDescriptorType = USB_DT_INTERFACE, + .bAlternateSetting = 1, + .bNumEndpoints = 1, + .bInterfaceClass = USB_CLASS_AUDIO, + .bInterfaceSubClass = USB_SUBCLASS_AUDIOSTREAMING, +}; + +/* B.4.2 Class-Specific AS Interface Descriptor */ +static struct uac1_as_header_descriptor as_header_desc = { + .bLength = UAC_DT_AS_HEADER_SIZE, + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_AS_GENERAL, + .bTerminalLink = INPUT_TERMINAL_ID, + .bDelay = 1, + .wFormatTag = UAC_FORMAT_TYPE_I_PCM, +}; + +DECLARE_UAC_FORMAT_TYPE_I_DISCRETE_DESC(1); + +static struct uac_format_type_i_discrete_descriptor_1 as_type_i_desc = { + .bLength = UAC_FORMAT_TYPE_I_DISCRETE_DESC_SIZE(1), + .bDescriptorType = USB_DT_CS_INTERFACE, + .bDescriptorSubtype = UAC_FORMAT_TYPE, + .bFormatType = UAC_FORMAT_TYPE_I, + .bSubframeSize = 2, + .bBitResolution = 16, + .bSamFreqType = 1, +}; + +/* Standard ISO IN Endpoint Descriptor for highspeed */ +static struct usb_endpoint_descriptor hs_as_in_ep_desc = { + .bLength = USB_DT_ENDPOINT_AUDIO_SIZE, + .bDescriptorType = USB_DT_ENDPOINT, + .bEndpointAddress = USB_DIR_IN, + .bmAttributes = USB_ENDPOINT_SYNC_SYNC + | USB_ENDPOINT_XFER_ISOC, + .wMaxPacketSize = __constant_cpu_to_le16(IN_EP_MAX_PACKET_SIZE), + .bInterval = 4, /* poll 1 per millisecond */ +}; + +/* Standard ISO IN Endpoint Descriptor for highspeed */ +static struct usb_endpoint_descriptor fs_as_in_ep_desc = { + .bLength = USB_DT_ENDPOINT_AUDIO_SIZE, + .bDescriptorType = USB_DT_ENDPOINT, + .bEndpointAddress = USB_DIR_IN, + .bmAttributes = USB_ENDPOINT_SYNC_SYNC + | USB_ENDPOINT_XFER_ISOC, + .wMaxPacketSize = __constant_cpu_to_le16(IN_EP_MAX_PACKET_SIZE), + .bInterval = 1, /* poll 1 per millisecond */ +}; + +/* Class-specific AS ISO OUT Endpoint Descriptor */ +static struct uac_iso_endpoint_descriptor as_iso_in_desc = { + .bLength = UAC_ISO_ENDPOINT_DESC_SIZE, + .bDescriptorType = USB_DT_CS_ENDPOINT, + .bDescriptorSubtype = UAC_EP_GENERAL, + .bmAttributes = 1, + .bLockDelayUnits = 1, + .wLockDelay = __constant_cpu_to_le16(1), +}; + +static struct usb_descriptor_header *hs_audio_desc[] = { + (struct usb_descriptor_header *)&ac_interface_desc, + (struct usb_descriptor_header *)&ac_header_desc, + + (struct usb_descriptor_header *)&input_terminal_desc, + (struct usb_descriptor_header *)&output_terminal_desc, + (struct usb_descriptor_header *)&feature_unit_desc, + + (struct usb_descriptor_header *)&as_interface_alt_0_desc, + (struct usb_descriptor_header *)&as_interface_alt_1_desc, + (struct usb_descriptor_header *)&as_header_desc, + + (struct usb_descriptor_header *)&as_type_i_desc, + + (struct usb_descriptor_header *)&hs_as_in_ep_desc, + (struct usb_descriptor_header *)&as_iso_in_desc, + NULL, +}; + +static struct usb_descriptor_header *fs_audio_desc[] = { + (struct usb_descriptor_header *)&ac_interface_desc, + (struct usb_descriptor_header *)&ac_header_desc, + + (struct usb_descriptor_header *)&input_terminal_desc, + (struct usb_descriptor_header *)&output_terminal_desc, + (struct usb_descriptor_header *)&feature_unit_desc, + + (struct usb_descriptor_header *)&as_interface_alt_0_desc, + (struct usb_descriptor_header *)&as_interface_alt_1_desc, + (struct usb_descriptor_header *)&as_header_desc, + + (struct usb_descriptor_header *)&as_type_i_desc, + + (struct usb_descriptor_header *)&fs_as_in_ep_desc, + (struct usb_descriptor_header *)&as_iso_in_desc, + NULL, +}; + +static struct snd_pcm_hardware audio_hw_info = { + .info = SNDRV_PCM_INFO_MMAP | + SNDRV_PCM_INFO_MMAP_VALID | + SNDRV_PCM_INFO_BATCH | + SNDRV_PCM_INFO_INTERLEAVED | + SNDRV_PCM_INFO_BLOCK_TRANSFER, + + .formats = SNDRV_PCM_FMTBIT_S16_LE, + .channels_min = 2, + .channels_max = 2, + .rate_min = SAMPLE_RATE, + .rate_max = SAMPLE_RATE, + + .buffer_bytes_max = 1024 * 1024, + .period_bytes_min = 64, + .period_bytes_max = 512 * 1024, + .periods_min = 2, + .periods_max = 1024, +}; + +/*-------------------------------------------------------------------------*/ + +struct audio_source_config { + int card; + int device; +}; + +struct audio_dev { + struct usb_function func; + struct snd_card *card; + struct snd_pcm *pcm; + struct snd_pcm_substream *substream; + + struct list_head idle_reqs; + struct usb_ep *in_ep; + + spinlock_t lock; + + /* beginning, end and current position in our buffer */ + void *buffer_start; + void *buffer_end; + void *buffer_pos; + + /* byte size of a "period" */ + unsigned int period; + /* bytes sent since last call to snd_pcm_period_elapsed */ + unsigned int period_offset; + /* time we started playing */ + ktime_t start_time; + /* number of frames sent since start_time */ + s64 frames_sent; +}; + +static inline struct audio_dev *func_to_audio(struct usb_function *f) +{ + return container_of(f, struct audio_dev, func); +} + +/*-------------------------------------------------------------------------*/ + +static struct usb_request *audio_request_new(struct usb_ep *ep, int buffer_size) +{ + struct usb_request *req = usb_ep_alloc_request(ep, GFP_KERNEL); + if (!req) + return NULL; + + req->buf = kmalloc(buffer_size, GFP_KERNEL); + if (!req->buf) { + usb_ep_free_request(ep, req); + return NULL; + } + req->length = buffer_size; + return req; +} + +static void audio_request_free(struct usb_request *req, struct usb_ep *ep) +{ + if (req) { + kfree(req->buf); + usb_ep_free_request(ep, req); + } +} + +static void audio_req_put(struct audio_dev *audio, struct usb_request *req) +{ + unsigned long flags; + + spin_lock_irqsave(&audio->lock, flags); + list_add_tail(&req->list, &audio->idle_reqs); + spin_unlock_irqrestore(&audio->lock, flags); +} + +static struct usb_request *audio_req_get(struct audio_dev *audio) +{ + unsigned long flags; + struct usb_request *req; + + spin_lock_irqsave(&audio->lock, flags); + if (list_empty(&audio->idle_reqs)) { + req = 0; + } else { + req = list_first_entry(&audio->idle_reqs, struct usb_request, + list); + list_del(&req->list); + } + spin_unlock_irqrestore(&audio->lock, flags); + return req; +} + +/* send the appropriate number of packets to match our bitrate */ +static void audio_send(struct audio_dev *audio) +{ + struct snd_pcm_runtime *runtime; + struct usb_request *req; + int length, length1, length2, ret; + s64 msecs; + s64 frames; + ktime_t now; + + /* audio->substream will be null if we have been closed */ + if (!audio->substream) + return; + /* audio->buffer_pos will be null if we have been stopped */ + if (!audio->buffer_pos) + return; + + runtime = audio->substream->runtime; + + /* compute number of frames to send */ + now = ktime_get(); + msecs = ktime_to_ns(now) - ktime_to_ns(audio->start_time); + do_div(msecs, 1000000); + frames = msecs * SAMPLE_RATE; + do_div(frames, 1000); + + /* Readjust our frames_sent if we fall too far behind. + * If we get too far behind it is better to drop some frames than + * to keep sending data too fast in an attempt to catch up. + */ + if (frames - audio->frames_sent > 10 * FRAMES_PER_MSEC) + audio->frames_sent = frames - FRAMES_PER_MSEC; + + frames -= audio->frames_sent; + + /* We need to send something to keep the pipeline going */ + if (frames <= 0) + frames = FRAMES_PER_MSEC; + + while (frames > 0) { + req = audio_req_get(audio); + if (!req) + break; + + length = frames_to_bytes(runtime, frames); + if (length > IN_EP_MAX_PACKET_SIZE) + length = IN_EP_MAX_PACKET_SIZE; + + if (audio->buffer_pos + length > audio->buffer_end) + length1 = audio->buffer_end - audio->buffer_pos; + else + length1 = length; + memcpy(req->buf, audio->buffer_pos, length1); + if (length1 < length) { + /* Wrap around and copy remaining length + * at beginning of buffer. + */ + length2 = length - length1; + memcpy(req->buf + length1, audio->buffer_start, + length2); + audio->buffer_pos = audio->buffer_start + length2; + } else { + audio->buffer_pos += length1; + if (audio->buffer_pos >= audio->buffer_end) + audio->buffer_pos = audio->buffer_start; + } + + req->length = length; + ret = usb_ep_queue(audio->in_ep, req, GFP_ATOMIC); + if (ret < 0) { + pr_err("usb_ep_queue failed ret: %d\n", ret); + audio_req_put(audio, req); + break; + } + + frames -= bytes_to_frames(runtime, length); + audio->frames_sent += bytes_to_frames(runtime, length); + } +} + +static void audio_control_complete(struct usb_ep *ep, struct usb_request *req) +{ + /* nothing to do here */ +} + +static void audio_data_complete(struct usb_ep *ep, struct usb_request *req) +{ + struct audio_dev *audio = req->context; + + pr_debug("audio_data_complete req->status %d req->actual %d\n", + req->status, req->actual); + + audio_req_put(audio, req); + + if (!audio->buffer_start || req->status) + return; + + audio->period_offset += req->actual; + if (audio->period_offset >= audio->period) { + snd_pcm_period_elapsed(audio->substream); + audio->period_offset = 0; + } + audio_send(audio); +} + +static int audio_set_endpoint_req(struct usb_function *f, + const struct usb_ctrlrequest *ctrl) +{ + int value = -EOPNOTSUPP; + u16 ep = le16_to_cpu(ctrl->wIndex); + u16 len = le16_to_cpu(ctrl->wLength); + u16 w_value = le16_to_cpu(ctrl->wValue); + + pr_debug("bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n", + ctrl->bRequest, w_value, len, ep); + + switch (ctrl->bRequest) { + case UAC_SET_CUR: + case UAC_SET_MIN: + case UAC_SET_MAX: + case UAC_SET_RES: + value = len; + break; + default: + break; + } + + return value; +} + +static int audio_get_endpoint_req(struct usb_function *f, + const struct usb_ctrlrequest *ctrl) +{ + struct usb_composite_dev *cdev = f->config->cdev; + int value = -EOPNOTSUPP; + u8 ep = ((le16_to_cpu(ctrl->wIndex) >> 8) & 0xFF); + u16 len = le16_to_cpu(ctrl->wLength); + u16 w_value = le16_to_cpu(ctrl->wValue); + u8 *buf = cdev->req->buf; + + pr_debug("bRequest 0x%x, w_value 0x%04x, len %d, endpoint %d\n", + ctrl->bRequest, w_value, len, ep); + + if (w_value == UAC_EP_CS_ATTR_SAMPLE_RATE << 8) { + switch (ctrl->bRequest) { + case UAC_GET_CUR: + case UAC_GET_MIN: + case UAC_GET_MAX: + case UAC_GET_RES: + /* return our sample rate */ + buf[0] = (u8)SAMPLE_RATE; + buf[1] = (u8)(SAMPLE_RATE >> 8); + buf[2] = (u8)(SAMPLE_RATE >> 16); + value = 3; + break; + default: + break; + } + } + + return value; +} + +static int +audio_setup(struct usb_function *f, const struct usb_ctrlrequest *ctrl) +{ + struct usb_composite_dev *cdev = f->config->cdev; + struct usb_request *req = cdev->req; + int value = -EOPNOTSUPP; + u16 w_index = le16_to_cpu(ctrl->wIndex); + u16 w_value = le16_to_cpu(ctrl->wValue); + u16 w_length = le16_to_cpu(ctrl->wLength); + + /* composite driver infrastructure handles everything; interface + * activation uses set_alt(). + */ + switch (ctrl->bRequestType) { + case USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_ENDPOINT: + value = audio_set_endpoint_req(f, ctrl); + break; + + case USB_DIR_IN | USB_TYPE_CLASS | USB_RECIP_ENDPOINT: + value = audio_get_endpoint_req(f, ctrl); + break; + } + + /* respond with data transfer or status phase? */ + if (value >= 0) { + pr_debug("audio req%02x.%02x v%04x i%04x l%d\n", + ctrl->bRequestType, ctrl->bRequest, + w_value, w_index, w_length); + req->zero = 0; + req->length = value; + req->complete = audio_control_complete; + value = usb_ep_queue(cdev->gadget->ep0, req, GFP_ATOMIC); + if (value < 0) + pr_err("audio response on err %d\n", value); + } + + /* device either stalls (value < 0) or reports success */ + return value; +} + +static int audio_set_alt(struct usb_function *f, unsigned intf, unsigned alt) +{ + struct audio_dev *audio = func_to_audio(f); + struct usb_composite_dev *cdev = f->config->cdev; + int ret; + + pr_debug("audio_set_alt intf %d, alt %d\n", intf, alt); + + ret = config_ep_by_speed(cdev->gadget, f, audio->in_ep); + if (ret) + return ret; + + usb_ep_enable(audio->in_ep); + return 0; +} + +static void audio_disable(struct usb_function *f) +{ + struct audio_dev *audio = func_to_audio(f); + + pr_debug("audio_disable\n"); + usb_ep_disable(audio->in_ep); +} + +/*-------------------------------------------------------------------------*/ + +static void audio_build_desc(struct audio_dev *audio) +{ + u8 *sam_freq; + int rate; + + /* Set channel numbers */ + input_terminal_desc.bNrChannels = 2; + as_type_i_desc.bNrChannels = 2; + + /* Set sample rates */ + rate = SAMPLE_RATE; + sam_freq = as_type_i_desc.tSamFreq[0]; + memcpy(sam_freq, &rate, 3); +} + +/* audio function driver setup/binding */ +static int +audio_bind(struct usb_configuration *c, struct usb_function *f) +{ + struct usb_composite_dev *cdev = c->cdev; + struct audio_dev *audio = func_to_audio(f); + int status; + struct usb_ep *ep; + struct usb_request *req; + int i; + + audio_build_desc(audio); + + /* allocate instance-specific interface IDs, and patch descriptors */ + status = usb_interface_id(c, f); + if (status < 0) + goto fail; + ac_interface_desc.bInterfaceNumber = status; + + status = usb_interface_id(c, f); + if (status < 0) + goto fail; + as_interface_alt_0_desc.bInterfaceNumber = status; + as_interface_alt_1_desc.bInterfaceNumber = status; + + status = -ENODEV; + + /* allocate our endpoint */ + ep = usb_ep_autoconfig(cdev->gadget, &fs_as_in_ep_desc); + if (!ep) + goto fail; + audio->in_ep = ep; + ep->driver_data = audio; /* claim */ + + if (gadget_is_dualspeed(c->cdev->gadget)) + hs_as_in_ep_desc.bEndpointAddress = + fs_as_in_ep_desc.bEndpointAddress; + + f->descriptors = fs_audio_desc; + f->hs_descriptors = hs_audio_desc; + + for (i = 0, status = 0; i < IN_EP_REQ_COUNT && status == 0; i++) { + req = audio_request_new(ep, IN_EP_MAX_PACKET_SIZE); + if (req) { + req->context = audio; + req->complete = audio_data_complete; + audio_req_put(audio, req); + } else + status = -ENOMEM; + } + +fail: + return status; +} + +static void +audio_unbind(struct usb_configuration *c, struct usb_function *f) +{ + struct audio_dev *audio = func_to_audio(f); + struct usb_request *req; + + while ((req = audio_req_get(audio))) + audio_request_free(req, audio->in_ep); + + snd_card_free_when_closed(audio->card); + audio->card = NULL; + audio->pcm = NULL; + audio->substream = NULL; + audio->in_ep = NULL; +} + +static void audio_pcm_playback_start(struct audio_dev *audio) +{ + audio->start_time = ktime_get(); + audio->frames_sent = 0; + audio_send(audio); +} + +static void audio_pcm_playback_stop(struct audio_dev *audio) +{ + unsigned long flags; + + spin_lock_irqsave(&audio->lock, flags); + audio->buffer_start = 0; + audio->buffer_end = 0; + audio->buffer_pos = 0; + spin_unlock_irqrestore(&audio->lock, flags); +} + +static int audio_pcm_open(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct audio_dev *audio = substream->private_data; + + runtime->private_data = audio; + runtime->hw = audio_hw_info; + snd_pcm_limit_hw_rates(runtime); + runtime->hw.channels_max = 2; + + audio->substream = substream; + return 0; +} + +static int audio_pcm_close(struct snd_pcm_substream *substream) +{ + struct audio_dev *audio = substream->private_data; + unsigned long flags; + + spin_lock_irqsave(&audio->lock, flags); + audio->substream = NULL; + spin_unlock_irqrestore(&audio->lock, flags); + + return 0; +} + +static int audio_pcm_hw_params(struct snd_pcm_substream *substream, + struct snd_pcm_hw_params *params) +{ + unsigned int channels = params_channels(params); + unsigned int rate = params_rate(params); + + if (rate != SAMPLE_RATE) + return -EINVAL; + if (channels != 2) + return -EINVAL; + + return snd_pcm_lib_alloc_vmalloc_buffer(substream, + params_buffer_bytes(params)); +} + +static int audio_pcm_hw_free(struct snd_pcm_substream *substream) +{ + return snd_pcm_lib_free_vmalloc_buffer(substream); +} + +static int audio_pcm_prepare(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct audio_dev *audio = runtime->private_data; + + audio->period = snd_pcm_lib_period_bytes(substream); + audio->period_offset = 0; + audio->buffer_start = runtime->dma_area; + audio->buffer_end = audio->buffer_start + + snd_pcm_lib_buffer_bytes(substream); + audio->buffer_pos = audio->buffer_start; + + return 0; +} + +static snd_pcm_uframes_t audio_pcm_pointer(struct snd_pcm_substream *substream) +{ + struct snd_pcm_runtime *runtime = substream->runtime; + struct audio_dev *audio = runtime->private_data; + ssize_t bytes = audio->buffer_pos - audio->buffer_start; + + /* return offset of next frame to fill in our buffer */ + return bytes_to_frames(runtime, bytes); +} + +static int audio_pcm_playback_trigger(struct snd_pcm_substream *substream, + int cmd) +{ + struct audio_dev *audio = substream->runtime->private_data; + int ret = 0; + + switch (cmd) { + case SNDRV_PCM_TRIGGER_START: + case SNDRV_PCM_TRIGGER_RESUME: + audio_pcm_playback_start(audio); + break; + + case SNDRV_PCM_TRIGGER_STOP: + case SNDRV_PCM_TRIGGER_SUSPEND: + audio_pcm_playback_stop(audio); + break; + + default: + ret = -EINVAL; + } + + return ret; +} + +static struct audio_dev _audio_dev = { + .func = { + .name = "audio_source", + .bind = audio_bind, + .unbind = audio_unbind, + .set_alt = audio_set_alt, + .setup = audio_setup, + .disable = audio_disable, + }, + .lock = __SPIN_LOCK_UNLOCKED(_audio_dev.lock), + .idle_reqs = LIST_HEAD_INIT(_audio_dev.idle_reqs), +}; + +static struct snd_pcm_ops audio_playback_ops = { + .open = audio_pcm_open, + .close = audio_pcm_close, + .ioctl = snd_pcm_lib_ioctl, + .hw_params = audio_pcm_hw_params, + .hw_free = audio_pcm_hw_free, + .prepare = audio_pcm_prepare, + .trigger = audio_pcm_playback_trigger, + .pointer = audio_pcm_pointer, +}; + +int audio_source_bind_config(struct usb_configuration *c, + struct audio_source_config *config) +{ + struct audio_dev *audio; + struct snd_card *card; + struct snd_pcm *pcm; + int err; + + config->card = -1; + config->device = -1; + + audio = &_audio_dev; + + err = snd_card_create(SNDRV_DEFAULT_IDX1, SNDRV_DEFAULT_STR1, + THIS_MODULE, 0, &card); + if (err) + return err; + + snd_card_set_dev(card, &c->cdev->gadget->dev); + + err = snd_pcm_new(card, "USB audio source", 0, 1, 0, &pcm); + if (err) + goto pcm_fail; + pcm->private_data = audio; + pcm->info_flags = 0; + audio->pcm = pcm; + + strlcpy(pcm->name, "USB gadget audio", sizeof(pcm->name)); + + snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &audio_playback_ops); + snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_DEV, + NULL, 0, 64 * 1024); + + strlcpy(card->driver, "audio_source", sizeof(card->driver)); + strlcpy(card->shortname, card->driver, sizeof(card->shortname)); + strlcpy(card->longname, "USB accessory audio source", + sizeof(card->longname)); + + err = snd_card_register(card); + if (err) + goto register_fail; + + err = usb_add_function(c, &audio->func); + if (err) + goto add_fail; + + config->card = pcm->card->number; + config->device = pcm->device; + audio->card = card; + return 0; + +add_fail: +register_fail: +pcm_fail: + snd_card_free(audio->card); + return err; +} -- 2.20.1