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