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 <kabel@kernel.org>
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/ioctls.h>
33 #include <asm/termbits.h>
34
35 #if defined(BOTHER) && defined(TCGETS2)
36 #define termios termios2
37 #endif
38
tcgetattr(int fd,struct termios * t)39 static inline int tcgetattr(int fd, struct termios *t)
40 {
41 #if defined(BOTHER) && defined(TCGETS2)
42 return ioctl(fd, TCGETS2, t);
43 #else
44 return ioctl(fd, TCGETS, t);
45 #endif
46 }
47
tcsetattr(int fd,int a,const struct termios * t)48 static inline int tcsetattr(int fd, int a, const struct termios *t)
49 {
50 int cmd;
51
52 switch (a) {
53 #if defined(BOTHER) && defined(TCGETS2)
54 case TCSANOW:
55 cmd = TCSETS2;
56 break;
57 case TCSADRAIN:
58 cmd = TCSETSW2;
59 break;
60 case TCSAFLUSH:
61 cmd = TCSETSF2;
62 break;
63 #else
64 case TCSANOW:
65 cmd = TCSETS;
66 break;
67 case TCSADRAIN:
68 cmd = TCSETSW;
69 break;
70 case TCSAFLUSH:
71 cmd = TCSETSF;
72 break;
73 #endif
74 default:
75 errno = EINVAL;
76 return -1;
77 }
78
79 return ioctl(fd, cmd, t);
80 }
81
tcdrain(int fd)82 static inline int tcdrain(int fd)
83 {
84 return ioctl(fd, TCSBRK, 1);
85 }
86
tcflush(int fd,int q)87 static inline int tcflush(int fd, int q)
88 {
89 return ioctl(fd, TCFLSH, q);
90 }
91
tcsendbreak(int fd,int d)92 static inline int tcsendbreak(int fd, int d)
93 {
94 #ifdef TCSBRKP
95 return ioctl(fd, TCSBRKP, d);
96 #else
97 return ioctl(fd, TCSBRK, 0);
98 #endif
99 }
100
tcflow(int fd,int a)101 static inline int tcflow(int fd, int a)
102 {
103 return ioctl(fd, TCXONC, a);
104 }
105
tcgetsid(int fd)106 static inline pid_t tcgetsid(int fd)
107 {
108 pid_t sid;
109
110 if (ioctl(fd, TIOCGSID, &sid) < 0)
111 return (pid_t)-1;
112
113 return sid;
114 }
115
cfgetospeed(const struct termios * t)116 static inline speed_t cfgetospeed(const struct termios *t)
117 {
118 return t->c_cflag & CBAUD;
119 }
120
cfsetospeed(struct termios * t,speed_t s)121 static inline int cfsetospeed(struct termios *t, speed_t s)
122 {
123 if (s & ~CBAUD) {
124 errno = EINVAL;
125 return -1;
126 }
127
128 t->c_cflag &= ~CBAUD;
129 t->c_cflag |= s;
130
131 return 0;
132 }
133
134 #ifdef IBSHIFT
cfgetispeed(const struct termios * t)135 static inline speed_t cfgetispeed(const struct termios *t)
136 {
137 speed_t s = (t->c_cflag >> IBSHIFT) & CBAUD;
138
139 if (s == B0)
140 return cfgetospeed(t);
141 else
142 return s;
143 }
144
cfsetispeed(struct termios * t,speed_t s)145 static inline int cfsetispeed(struct termios *t, speed_t s)
146 {
147 if (s == 0)
148 s = B0;
149
150 if (s & ~CBAUD) {
151 errno = EINVAL;
152 return -1;
153 }
154
155 t->c_cflag &= ~(CBAUD << IBSHIFT);
156 t->c_cflag |= s << IBSHIFT;
157
158 return 0;
159 }
160 #else /* !IBSHIFT */
cfgetispeed(const struct termios * t)161 static inline speed_t cfgetispeed(const struct termios *t)
162 {
163 return cfgetospeed(t);
164 }
165
cfsetispeed(struct termios * t,speed_t s)166 static inline int cfsetispeed(struct termios *t, speed_t s)
167 {
168 return cfsetospeed(t, s);
169 }
170 #endif /* !IBSHIFT */
171
cfsetspeed(struct termios * t,speed_t s)172 static inline int cfsetspeed(struct termios *t, speed_t s)
173 {
174 if (cfsetospeed(t, s))
175 return -1;
176 #ifdef IBSHIFT
177 if (cfsetispeed(t, s))
178 return -1;
179 #endif
180
181 return 0;
182 }
183
cfmakeraw(struct termios * t)184 static void cfmakeraw(struct termios *t)
185 {
186 t->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR |
187 ICRNL | IXON);
188 t->c_oflag &= ~OPOST;
189 t->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
190 t->c_cflag &= ~(CSIZE | PARENB);
191 t->c_cflag |= CS8;
192 }
193
194 #endif /* _TERMIOS_LINUX_H_ */
195