1 /*
2  * u_audio.h -- interface to USB gadget "ALSA sound card" utilities
3  *
4  * Copyright (C) 2016
5  * Author: Ruslan Bilovol <ruslan.bilovol@gmail.com>
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  */
18 
19 #ifndef __U_AUDIO_H
20 #define __U_AUDIO_H
21 
22 #include <linux/usb/composite.h>
23 
24 struct uac_params {
25 	/* playback */
26 	int p_chmask;	/* channel mask */
27 	int p_srate;	/* rate in Hz */
28 	int p_ssize;	/* sample size */
29 
30 	/* capture */
31 	int c_chmask;	/* channel mask */
32 	int c_srate;	/* rate in Hz */
33 	int c_ssize;	/* sample size */
34 
35 	int req_number; /* number of preallocated requests */
36 };
37 
38 struct g_audio {
39 	struct usb_function func;
40 	struct usb_gadget *gadget;
41 
42 	struct usb_ep *in_ep;
43 	struct usb_ep *out_ep;
44 
45 	/* Max packet size for all in_ep possible speeds */
46 	unsigned int in_ep_maxpsize;
47 	/* Max packet size for all out_ep possible speeds */
48 	unsigned int out_ep_maxpsize;
49 
50 	/* The ALSA Sound Card it represents on the USB-Client side */
51 	struct snd_uac_chip *uac;
52 
53 	struct uac_params params;
54 };
55 
56 static inline struct g_audio *func_to_g_audio(struct usb_function *f)
57 {
58 	return container_of(f, struct g_audio, func);
59 }
60 
61 static inline uint num_channels(uint chanmask)
62 {
63 	uint num = 0;
64 
65 	while (chanmask) {
66 		num += (chanmask & 1);
67 		chanmask >>= 1;
68 	}
69 
70 	return num;
71 }
72 
73 /*
74  * g_audio_setup - initialize one virtual ALSA sound card
75  * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize
76  * @pcm_name: the id string for a PCM instance of this sound card
77  * @card_name: name of this soundcard
78  *
79  * This sets up the single virtual ALSA sound card that may be exported by a
80  * gadget driver using this framework.
81  *
82  * Context: may sleep
83  *
84  * Returns zero on success, or a negative error on failure.
85  */
86 int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
87 					const char *card_name);
88 void g_audio_cleanup(struct g_audio *g_audio);
89 
90 int u_audio_start_capture(struct g_audio *g_audio);
91 void u_audio_stop_capture(struct g_audio *g_audio);
92 int u_audio_start_playback(struct g_audio *g_audio);
93 void u_audio_stop_playback(struct g_audio *g_audio);
94 
95 #endif /* __U_AUDIO_H */
96