1/* SPDX-License-Identifier: GPL-2.0+ */
2/*
3 * termios fuctions to support arbitrary baudrates (on Linux)
4 *
5 * Copyright (c) 2021 Pali Roh��r <pali@kernel.org>
6 * Copyright (c) 2021 Marek Beh��n <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
39static 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
48static 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
82static inline int tcdrain(int fd)
83{
84	return ioctl(fd, TCSBRK, 1);
85}
86
87static inline int tcflush(int fd, int q)
88{
89	return ioctl(fd, TCFLSH, q);
90}
91
92static 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
101static inline int tcflow(int fd, int a)
102{
103	return ioctl(fd, TCXONC, a);
104}
105
106static 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
116static inline speed_t cfgetospeed(const struct termios *t)
117{
118	return t->c_cflag & CBAUD;
119}
120
121static 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
135static 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
145static 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 */
161static inline speed_t cfgetispeed(const struct termios *t)
162{
163	return cfgetospeed(t);
164}
165
166static inline int cfsetispeed(struct termios *t, speed_t s)
167{
168	return cfsetospeed(t, s);
169}
170#endif /* !IBSHIFT */
171
172static 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
184static 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