drivers/usb/gadget/function/u_audio.h

   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
  14 struct 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
  28 struct 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
  46 static inline struct g_audio *func_to_g_audio(struct usb_function *f)
  47 {
  48         return container_of(f, struct g_audio, func);
  49 }
  50
  51 static 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  */
  76 int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
  77                                         const char *card_name);
  78 void g_audio_cleanup(struct g_audio *g_audio);
  79
  80 int u_audio_start_capture(struct g_audio *g_audio);
  81 void u_audio_stop_capture(struct g_audio *g_audio);
  82 int u_audio_start_playback(struct g_audio *g_audio);
  83 void u_audio_stop_playback(struct g_audio *g_audio);
  84
  85 #endif /* __U_AUDIO_H */