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 */
86