1 /* SPDX-License-Identifier: GPL-2.0+ */
2 /*
3 * termios fuctions to support arbitrary baudrates (on Linux)
4 *
5 * Copyright (c) 2021 Pali Rohár <pali@kernel.org>
6 * Copyright (c) 2021 Marek Behún <marek.behun@nic.cz>
7 */
8
9 #ifndef _TERMIOS_LINUX_H_
10 #define _TERMIOS_LINUX_H_
11
12 /*
13 * We need to use raw TCGETS2/TCSETS2 or TCGETS/TCSETS ioctls with the BOTHER
14 * flag in struct termios2/termios, defined in Linux headers <asm/ioctls.h>
15 * (included by <sys/ioctl.h>) and <asm/termbits.h>. Since these headers
16 * conflict with glibc's header file <termios.h>, it is not possible to use
17 * libc's termios functions and we need to reimplement them via ioctl() calls.
18 *
19 * An arbitrary baudrate is supported when the macro BOTHER is defined. The
20 * baudrate value itself is then stored into the c_ospeed and c_ispeed members.
21 * If ioctls TCGETS2/TCSETS2 are defined and supported then these fields are
22 * present in struct termios2, otherwise these fields are present in struct
23 * termios.
24 *
25 * Note that the Bnnn constants from <termios.h> need not be compatible with Bnnn
26 * constants from <asm/termbits.h>.
27 */
28
29 #include <errno.h>
30 #include <sys/ioctl.h>
31 #include <sys/types.h>
32 #include <asm/termbits.h>
33
34 #if defined(BOTHER) && defined(TCGETS2)
35 #define termios termios2
36 #endif
37
tcgetattr(int fd,struct termios * t)38 static inline int tcgetattr(int fd, struct termios *t)
39 {
40 #if defined(BOTHER) && defined(TCGETS2)
41 return ioctl(fd, TCGETS2, t);
42 #else
43 return ioctl(fd, TCGETS, t);
44 #endif
45 }
46
tcsetattr(int fd,int a,const struct termios * t)47 static inline int tcsetattr(int fd, int a, const struct termios *t)
48 {
49 int cmd;
50
51 switch (a) {
52 #if defined(BOTHER) && defined(TCGETS2)
53 case TCSANOW:
54 cmd = TCSETS2;
55 break;
56 case TCSADRAIN:
57 cmd = TCSETSW2;
58 break;
59 case TCSAFLUSH:
60 cmd = TCSETSF2;
61 break;
62 #else
63 case TCSANOW:
64 cmd = TCSETS;
65 break;
66 case TCSADRAIN:
67 cmd = TCSETSW;
68 break;
69 case TCSAFLUSH:
70 cmd = TCSETSF;
71 break;
72 #endif
73 default:
74 errno = EINVAL;
75 return -1;
76 }
77
78 return ioctl(fd, cmd, t);
79 }
80
tcdrain(int fd)81 static inline int tcdrain(int fd)
82 {
83 return ioctl(fd, TCSBRK, 1);
84 }
85
tcflush(int fd,int q)86 static inline int tcflush(int fd, int q)
87 {
88 return ioctl(fd, TCFLSH, q);
89 }
90
tcsendbreak(int fd,int d)91 static inline int tcsendbreak(int fd, int d)
92 {
93 #ifdef TCSBRKP
94 return ioctl(fd, TCSBRKP, d);
95 #else
96 return ioctl(fd, TCSBRK, 0);
97 #endif
98 }
99
tcflow(int fd,int a)100 static inline int tcflow(int fd, int a)
101 {
102 return ioctl(fd, TCXONC, a);
103 }
104
tcgetsid(int fd)105 static inline pid_t tcgetsid(int fd)
106 {
107 pid_t sid;
108
109 if (ioctl(fd, TIOCGSID, &sid) < 0)
110 return (pid_t)-1;
111
112 return sid;
113 }
114
cfgetospeed(const struct termios * t)115 static inline speed_t cfgetospeed(const struct termios *t)
116 {
117 return t->c_cflag & CBAUD;
118 }
119
cfsetospeed(struct termios * t,speed_t s)120 static inline int cfsetospeed(struct termios *t, speed_t s)
121 {
122 if (s & ~CBAUD) {
123 errno = EINVAL;
124 return -1;
125 }
126
127 t->c_cflag &= ~CBAUD;
128 t->c_cflag |= s;
129
130 return 0;
131 }
132
133 #ifdef IBSHIFT
cfgetispeed(const struct termios * t)134 static inline speed_t cfgetispeed(const struct termios *t)
135 {
136 speed_t s = (t->c_cflag >> IBSHIFT) & CBAUD;
137
138 if (s == B0)
139 return cfgetospeed(t);
140 else
141 return s;
142 }
143
cfsetispeed(struct termios * t,speed_t s)144 static inline int cfsetispeed(struct termios *t, speed_t s)
145 {
146 if (s == 0)
147 s = B0;
148
149 if (s & ~CBAUD) {
150 errno = EINVAL;
151 return -1;
152 }
153
154 t->c_cflag &= ~(CBAUD << IBSHIFT);
155 t->c_cflag |= s << IBSHIFT;
156
157 return 0;
158 }
159 #else /* !IBSHIFT */
cfgetispeed(const struct termios * t)160 static inline speed_t cfgetispeed(const struct termios *t)
161 {
162 return cfgetospeed(t);
163 }
164
cfsetispeed(struct termios * t,speed_t s)165 static inline int cfsetispeed(struct termios *t, speed_t s)
166 {
167 return cfsetospeed(t, s);
168 }
169 #endif /* !IBSHIFT */
170
cfsetspeed(struct termios * t,speed_t s)171 static inline int cfsetspeed(struct termios *t, speed_t s)
172 {
173 if (cfsetospeed(t, s))
174 return -1;
175 #ifdef IBSHIFT
176 if (cfsetispeed(t, s))
177 return -1;
178 #endif
179
180 return 0;
181 }
182
cfmakeraw(struct termios * t)183 static void cfmakeraw(struct termios *t)
184 {
185 t->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR |
186 ICRNL | IXON);
187 t->c_oflag &= ~OPOST;
188 t->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
189 t->c_cflag &= ~(CSIZE | PARENB);
190 t->c_cflag |= CS8;
191 }
192
193 #endif /* _TERMIOS_LINUX_H_ */
194