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 */