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 /*
15  * Same maximum frequency deviation on the slower side as in
16  * sound/usb/endpoint.c. Value is expressed in per-mil deviation.
17  */
18 #define FBACK_SLOW_MAX	250
19 
20 /*
21  * Maximum frequency deviation on the faster side, default value for UAC1/2.
22  * Value is expressed in per-mil deviation.
23  * UAC2 provides the value as a parameter as it impacts the endpoint required
24  * bandwidth.
25  */
26 #define FBACK_FAST_MAX 5
27 
28 /* Feature Unit parameters */
29 struct uac_fu_params {
30 	int id;			/* Feature Unit ID */
31 
32 	bool mute_present;	/* mute control enable */
33 
34 	bool volume_present;	/* volume control enable */
35 	s16 volume_min;		/* min volume in 1/256 dB */
36 	s16 volume_max;		/* max volume in 1/256 dB */
37 	s16 volume_res;		/* volume resolution in 1/256 dB */
38 };
39 
40 struct uac_params {
41 	/* playback */
42 	int p_chmask;	/* channel mask */
43 	int p_srate;	/* rate in Hz */
44 	int p_ssize;	/* sample size */
45 	struct uac_fu_params p_fu;	/* Feature Unit parameters */
46 
47 	/* capture */
48 	int c_chmask;	/* channel mask */
49 	int c_srate;	/* rate in Hz */
50 	int c_ssize;	/* sample size */
51 	struct uac_fu_params c_fu;	/* Feature Unit parameters */
52 
53 	int req_number; /* number of preallocated requests */
54 	int fb_max;	/* upper frequency drift feedback limit per-mil */
55 };
56 
57 struct g_audio {
58 	struct usb_function func;
59 	struct usb_gadget *gadget;
60 
61 	struct usb_ep *in_ep;
62 
63 	struct usb_ep *out_ep;
64 	/* feedback IN endpoint corresponding to out_ep */
65 	struct usb_ep *in_ep_fback;
66 
67 	/* Max packet size for all in_ep possible speeds */
68 	unsigned int in_ep_maxpsize;
69 	/* Max packet size for all out_ep possible speeds */
70 	unsigned int out_ep_maxpsize;
71 
72 	/* Notify UAC driver about control change */
73 	int (*notify)(struct g_audio *g_audio, int unit_id, int cs);
74 
75 	/* The ALSA Sound Card it represents on the USB-Client side */
76 	struct snd_uac_chip *uac;
77 
78 	struct uac_params params;
79 };
80 
81 static inline struct g_audio *func_to_g_audio(struct usb_function *f)
82 {
83 	return container_of(f, struct g_audio, func);
84 }
85 
86 static inline uint num_channels(uint chanmask)
87 {
88 	uint num = 0;
89 
90 	while (chanmask) {
91 		num += (chanmask & 1);
92 		chanmask >>= 1;
93 	}
94 
95 	return num;
96 }
97 
98 /*
99  * g_audio_setup - initialize one virtual ALSA sound card
100  * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize
101  * @pcm_name: the id string for a PCM instance of this sound card
102  * @card_name: name of this soundcard
103  *
104  * This sets up the single virtual ALSA sound card that may be exported by a
105  * gadget driver using this framework.
106  *
107  * Context: may sleep
108  *
109  * Returns zero on success, or a negative error on failure.
110  */
111 int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,
112 					const char *card_name);
113 void g_audio_cleanup(struct g_audio *g_audio);
114 
115 int u_audio_start_capture(struct g_audio *g_audio);
116 void u_audio_stop_capture(struct g_audio *g_audio);
117 int u_audio_start_playback(struct g_audio *g_audio);
118 void u_audio_stop_playback(struct g_audio *g_audio);
119 
120 int u_audio_get_volume(struct g_audio *g_audio, int playback, s16 *val);
121 int u_audio_set_volume(struct g_audio *g_audio, int playback, s16 val);
122 int u_audio_get_mute(struct g_audio *g_audio, int playback, int *val);
123 int u_audio_set_mute(struct g_audio *g_audio, int playback, int val);
124 
125 #endif /* __U_AUDIO_H */
126