1 /* pcm_hw.c
2 **
3 ** Copyright (c) 2019, The Linux Foundation.
4 ** Copyright 2021, The Android Open Source Project
5 **
6 ** Redistribution and use in source and binary forms, with or without
7 ** modification, are permitted provided that the following conditions are
8 ** met:
9 ** * Redistributions of source code must retain the above copyright
10 ** notice, this list of conditions and the following disclaimer.
11 ** * Redistributions in binary form must reproduce the above
12 ** copyright notice, this list of conditions and the following
13 ** disclaimer in the documentation and/or other materials provided
14 ** with the distribution.
15 ** * Neither the name of The Linux Foundation nor the names of its
16 ** contributors may be used to endorse or promote products derived
17 ** from this software without specific prior written permission.
18 **
19 ** THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
20 ** WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
21 ** MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
22 ** ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
23 ** BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 ** CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 ** SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
26 ** BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
27 ** WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
28 ** OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
29 ** IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
30 **/
31
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <fcntl.h>
35 #include <stdarg.h>
36 #include <string.h>
37 #include <errno.h>
38 #include <unistd.h>
39 #include <poll.h>
40
41 #include <sys/ioctl.h>
42 #include <sys/mman.h>
43 #include <linux/ioctl.h>
44 #include <sound/asound.h>
45 #include <tinyalsa/asoundlib.h>
46
47 #include "pcm_io.h"
48
49 struct pcm_hw_data {
50 /** Card number of the pcm device */
51 unsigned int card;
52 /** Device number for the pcm device */
53 unsigned int device;
54 /** File descriptor to the pcm device file node */
55 int fd;
56 /** Pointer to the pcm node from snd card definiton */
57 struct snd_node *node;
58 };
59
pcm_hw_close(void * data)60 static void pcm_hw_close(void *data)
61 {
62 struct pcm_hw_data *hw_data = data;
63
64 if (hw_data->fd >= 0)
65 close(hw_data->fd);
66
67 free(hw_data);
68 }
69
pcm_hw_ioctl(void * data,unsigned int cmd,...)70 static int pcm_hw_ioctl(void *data, unsigned int cmd, ...)
71 {
72 struct pcm_hw_data *hw_data = data;
73 va_list ap;
74 void *arg;
75
76 va_start(ap, cmd);
77 arg = va_arg(ap, void *);
78 va_end(ap);
79
80 return ioctl(hw_data->fd, cmd, arg);
81 }
82
pcm_hw_poll(void * data,struct pollfd * pfd,nfds_t nfds,int timeout)83 static int pcm_hw_poll(void *data __attribute__((unused)),
84 struct pollfd *pfd, nfds_t nfds, int timeout)
85 {
86 return poll(pfd, nfds, timeout);
87 }
88
pcm_hw_mmap(void * data,void * addr,size_t length,int prot,int flags,off_t offset)89 static void *pcm_hw_mmap(void *data, void *addr, size_t length, int prot,
90 int flags, off_t offset)
91 {
92 struct pcm_hw_data *hw_data = data;
93
94 return mmap(addr, length, prot, flags, hw_data->fd, offset);
95 }
96
pcm_hw_munmap(void * data,void * addr,size_t length)97 static int pcm_hw_munmap(void *data __attribute__((unused)), void *addr, size_t length)
98 {
99 return munmap(addr, length);
100 }
101
pcm_hw_open(unsigned int card,unsigned int device,unsigned int flags,void ** data,struct snd_node * node)102 static int pcm_hw_open(unsigned int card, unsigned int device,
103 unsigned int flags, void **data, struct snd_node *node)
104 {
105 struct pcm_hw_data *hw_data;
106 char fn[256];
107 int fd;
108
109 hw_data = calloc(1, sizeof(*hw_data));
110 if (!hw_data) {
111 return -ENOMEM;
112 }
113
114 snprintf(fn, sizeof(fn), "/dev/snd/pcmC%uD%u%c", card, device,
115 flags & PCM_IN ? 'c' : 'p');
116 // Open the device with non-blocking flag to avoid to be blocked in kernel when all of the
117 // substreams of this PCM device are opened by others.
118 fd = open(fn, O_RDWR | O_NONBLOCK);
119
120 if (fd < 0) {
121 free(hw_data);
122 return fd;
123 }
124
125 if ((flags & PCM_NONBLOCK) == 0) {
126 // Set the file descriptor to blocking mode.
127 if (fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) & ~O_NONBLOCK) < 0) {
128 fprintf(stderr, "failed to set to blocking mode on %s", fn);
129 close(fd);
130 free(hw_data);
131 return -ENODEV;
132 }
133 }
134
135 hw_data->card = card;
136 hw_data->device = device;
137 hw_data->fd = fd;
138 hw_data->node = node;
139
140 *data = hw_data;
141
142 return fd;
143 }
144
145 const struct pcm_ops hw_ops = {
146 .open = pcm_hw_open,
147 .close = pcm_hw_close,
148 .ioctl = pcm_hw_ioctl,
149 .mmap = pcm_hw_mmap,
150 .munmap = pcm_hw_munmap,
151 .poll = pcm_hw_poll,
152 };
153
154