LXR linux/drivers/usb/gadget/function/u

   1/* SPDX-License-Identifier: GPL-2.0+ */
   2/*
   3 * u_audio.h -- interface to USB gadget "ALSA sound card" utilities
   4 *
   5 * Copyright (C) 2016
   6 * Author: Ruslan Bilovol <ruslan.bilovol@gmail.com>
   7 */
   8
   9#ifndef __U_AUDIO_H
  10#define __U_AUDIO_H
  11
  12#include <linux/usb/composite.h>
  13
  14struct uac_params {
  15        /* playback */
  16        int p_chmask;   /* channel mask */
  17        int p_srate;    /* rate in Hz */
  18        int p_ssize;    /* sample size */
  19
  20        /* capture */
  21        int c_chmask;   /* channel mask */
  22        int c_srate;    /* rate in Hz */
  23        int c_ssize;    /* sample size */
  24
  25        int req_number; /* number of preallocated requests */
  26};
  27
  28struct g_audio {
  29        struct usb_function func;
  30        struct usb_gadget *gadget;
  31
  32        struct usb_ep *in_ep;
  33        struct usb_ep *out_ep;
  34
  35        /* Max packet size for all in_ep possible speeds */
  36        unsigned int in_ep_maxpsize;
  37        /* Max packet size for all out_ep possible speeds */
  38        unsigned int out_ep_maxpsize;
  39
  40        /* The ALSA Sound Card it represents on the USB-Client side */
  41        struct snd_uac_chip *uac;
  42
  43        struct uac_params params;
  44};
  45
  46static inline struct g_audio *func_to_g_audio(struct usb_function *f)
  47{
  48        return container_of(f, struct g_audio, func);
  49}
  50
  51static inline uint num_channels(uint chanmask)
  52{
  53        uint num = 0;
  54
  55        while (chanmask) {
  56                num += (chanmask & 1);
  57                chanmask >>= 1;
  58        }
  59
  60        return num;
  61}
  62
  63/*
  64 * g_audio_setup - initialize one virtual ALSA sound card
  65 * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize
  66 * @pcm_name: the id string for a PCM instance of this sound card
  67 * @card_name: name of this soundcard
  68 *
  69 * This sets up the single virtual ALSA sound card that may be exported by a
  70 * gadget driver using this framework.
  71 *
  72 * Context: may sleep
  73 *
  74 * Returns zero on success, or a negative error on failure.
  75 */
  76int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
  77                                        const char *card_name);
  78void g_audio_cleanup(struct g_audio *g_audio);
  79
  80int u_audio_start_capture(struct g_audio *g_audio);
  81void u_audio_stop_capture(struct g_audio *g_audio);
  82int u_audio_start_playback(struct g_audio *g_audio);
  83void u_audio_stop_playback(struct g_audio *g_audio);
  84
  85#endif /* __U_AUDIO_H */
  86