Quelle  capture.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Line 6 Linux USB driver
 *
 * Copyright (C) 2004-2010 Markus Grabner (line6@grabner-graz.at)
 */

#include <linux/slab.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>

#include "capture.h"
#include "driver.h"
#include "pcm.h"

/*
Find a free URB and submit it.
must be called in line6pcm->in.lock context
*/
static int submit_audio_in_urb(struct snd_line6_pcm *line6pcm)
{
 int index;
 int i, urb_size;
 int ret;
 struct urb *urb_in;

 index = find_first_zero_bit(&line6pcm->in.active_urbs,
        line6pcm->line6->iso_buffers);

 if (index < 0 || index >= line6pcm->line6->iso_buffers) {
  dev_err(line6pcm->line6->ifcdev, "no free URB found\n");
  return -EINVAL;
 }

 urb_in = line6pcm->in.urbs[index];
 urb_size = 0;

 for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
  struct usb_iso_packet_descriptor *fin =
      &urb_in->iso_frame_desc[i];
  fin->offset = urb_size;
  fin->length = line6pcm->max_packet_size_in;
  urb_size += line6pcm->max_packet_size_in;
 }

 urb_in->transfer_buffer =
     line6pcm->in.buffer +
     index * LINE6_ISO_PACKETS * line6pcm->max_packet_size_in;
 urb_in->transfer_buffer_length = urb_size;
 urb_in->context = line6pcm;

 ret = usb_submit_urb(urb_in, GFP_ATOMIC);

 if (ret == 0)
  set_bit(index, &line6pcm->in.active_urbs);
 else
  dev_err(line6pcm->line6->ifcdev,
   "URB in #%d submission failed (%d)\n", index, ret);

 return 0;
}

/*
Submit all currently available capture URBs.
must be called in line6pcm->in.lock context
*/
int line6_submit_audio_in_all_urbs(struct snd_line6_pcm *line6pcm)
{
 int ret = 0, i;

 for (i = 0; i < line6pcm->line6->iso_buffers; ++i) {
  ret = submit_audio_in_urb(line6pcm);
  if (ret < 0)
   break;
 }

 return ret;
}

/*
Copy data into ALSA capture buffer.
*/
void line6_capture_copy(struct snd_line6_pcm *line6pcm, char *fbuf, int fsize)
{
 struct snd_pcm_substream *substream =
     get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE);
 struct snd_pcm_runtime *runtime = substream->runtime;
 const int bytes_per_frame =
  line6pcm->properties->bytes_per_channel *
  line6pcm->properties->capture_hw.channels_max;
 int frames = fsize / bytes_per_frame;

 if (runtime == NULL)
  return;

 if (line6pcm->in.pos_done + frames > runtime->buffer_size) {
  /*
   The transferred area goes over buffer boundary,
   copy two separate chunks.
 */
  int len;

  len = runtime->buffer_size - line6pcm->in.pos_done;

  if (len > 0) {
   memcpy(runtime->dma_area +
          line6pcm->in.pos_done * bytes_per_frame, fbuf,
          len * bytes_per_frame);
   memcpy(runtime->dma_area, fbuf + len * bytes_per_frame,
          (frames - len) * bytes_per_frame);
  } else {
   /* this is somewhat paranoid */
   dev_err(line6pcm->line6->ifcdev,
    "driver bug: len = %d\n", len);
  }
 } else {
  /* copy single chunk */
  memcpy(runtime->dma_area +
         line6pcm->in.pos_done * bytes_per_frame, fbuf, fsize);
 }

 line6pcm->in.pos_done += frames;
 if (line6pcm->in.pos_done >= runtime->buffer_size)
  line6pcm->in.pos_done -= runtime->buffer_size;
}

void line6_capture_check_period(struct snd_line6_pcm *line6pcm, int length)
{
 struct snd_pcm_substream *substream =
     get_substream(line6pcm, SNDRV_PCM_STREAM_CAPTURE);

 line6pcm->in.bytes += length;
 if (line6pcm->in.bytes >= line6pcm->in.period) {
  line6pcm->in.bytes %= line6pcm->in.period;
  spin_unlock(&line6pcm->in.lock);
  snd_pcm_period_elapsed(substream);
  spin_lock(&line6pcm->in.lock);
 }
}

/*
 * Callback for completed capture URB.
 */
static void audio_in_callback(struct urb *urb)
{
 int i, index, length = 0, shutdown = 0;
 unsigned long flags;

 struct snd_line6_pcm *line6pcm = (struct snd_line6_pcm *)urb->context;

 line6pcm->in.last_frame = urb->start_frame;

 /* find index of URB */
 for (index = 0; index < line6pcm->line6->iso_buffers; ++index)
  if (urb == line6pcm->in.urbs[index])
   break;

 spin_lock_irqsave(&line6pcm->in.lock, flags);

 for (i = 0; i < LINE6_ISO_PACKETS; ++i) {
  char *fbuf;
  int fsize;
  struct usb_iso_packet_descriptor *fin = &urb->iso_frame_desc[i];

  if (fin->status == -EXDEV) {
   shutdown = 1;
   break;
  }

  fbuf = urb->transfer_buffer + fin->offset;
  fsize = fin->actual_length;

  if (fsize > line6pcm->max_packet_size_in) {
   dev_err(line6pcm->line6->ifcdev,
    "driver and/or device bug: packet too large (%d > %d)\n",
    fsize, line6pcm->max_packet_size_in);
  }

  length += fsize;

  BUILD_BUG_ON_MSG(LINE6_ISO_PACKETS != 1,
   "The following code assumes LINE6_ISO_PACKETS == 1");
  /* TODO:
 * Also, if iso_buffers != 2, the prev frame is almost random at
 * playback side.
 * This needs to be redesigned. It should be "stable", but we may
 * experience sync problems on such high-speed configs.
 */

  line6pcm->prev_fbuf = fbuf;
  line6pcm->prev_fsize = fsize /
   (line6pcm->properties->bytes_per_channel *
   line6pcm->properties->capture_hw.channels_max);

  if (!test_bit(LINE6_STREAM_IMPULSE, &line6pcm->in.running) &&
      test_bit(LINE6_STREAM_PCM, &line6pcm->in.running) &&
      fsize > 0)
   line6_capture_copy(line6pcm, fbuf, fsize);
 }

 clear_bit(index, &line6pcm->in.active_urbs);

 if (test_and_clear_bit(index, &line6pcm->in.unlink_urbs))
  shutdown = 1;

 if (!shutdown) {
  submit_audio_in_urb(line6pcm);

  if (!test_bit(LINE6_STREAM_IMPULSE, &line6pcm->in.running) &&
      test_bit(LINE6_STREAM_PCM, &line6pcm->in.running))
   line6_capture_check_period(line6pcm, length);
 }

 spin_unlock_irqrestore(&line6pcm->in.lock, flags);
}

/* open capture callback */
static int snd_line6_capture_open(struct snd_pcm_substream *substream)
{
 int err;
 struct snd_pcm_runtime *runtime = substream->runtime;
 struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

 err = snd_pcm_hw_constraint_ratdens(runtime, 0,
         SNDRV_PCM_HW_PARAM_RATE,
         &line6pcm->properties->rates);
 if (err < 0)
  return err;

 line6_pcm_acquire(line6pcm, LINE6_STREAM_CAPTURE_HELPER, false);

 runtime->hw = line6pcm->properties->capture_hw;
 return 0;
}

/* close capture callback */
static int snd_line6_capture_close(struct snd_pcm_substream *substream)
{
 struct snd_line6_pcm *line6pcm = snd_pcm_substream_chip(substream);

 line6_pcm_release(line6pcm, LINE6_STREAM_CAPTURE_HELPER);
 return 0;
}

/* capture operators */
const struct snd_pcm_ops snd_line6_capture_ops = {
 .open = snd_line6_capture_open,
 .close = snd_line6_capture_close,
 .hw_params = snd_line6_hw_params,
 .hw_free = snd_line6_hw_free,
 .prepare = snd_line6_prepare,
 .trigger = snd_line6_trigger,
 .pointer = snd_line6_pointer,
};

int line6_create_audio_in_urbs(struct snd_line6_pcm *line6pcm)
{
 struct usb_line6 *line6 = line6pcm->line6;
 int i;

 line6pcm->in.urbs = kcalloc(line6->iso_buffers, sizeof(struct urb *),
        GFP_KERNEL);
 if (line6pcm->in.urbs == NULL)
  return -ENOMEM;

 /* create audio URBs and fill in constant values: */
 for (i = 0; i < line6->iso_buffers; ++i) {
  struct urb *urb;

  /* URB for audio in: */
  urb = line6pcm->in.urbs[i] =
      usb_alloc_urb(LINE6_ISO_PACKETS, GFP_KERNEL);

  if (urb == NULL)
   return -ENOMEM;

  urb->dev = line6->usbdev;
  urb->pipe =
      usb_rcvisocpipe(line6->usbdev,
        line6->properties->ep_audio_r &
        USB_ENDPOINT_NUMBER_MASK);
  urb->transfer_flags = URB_ISO_ASAP;
  urb->start_frame = -1;
  urb->number_of_packets = LINE6_ISO_PACKETS;
  urb->interval = LINE6_ISO_INTERVAL;
  urb->error_count = 0;
  urb->complete = audio_in_callback;
  if (usb_urb_ep_type_check(urb))
   return -EINVAL;
 }

 return 0;
}