tools/termios_linux.h

   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
  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
  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
  81 static inline int tcdrain(int fd)
  82 {
  83         return ioctl(fd, TCSBRK, 1);
  84 }
  85
  86 static inline int tcflush(int fd, int q)
  87 {
  88         return ioctl(fd, TCFLSH, q);
  89 }
  90
  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
 100 static inline int tcflow(int fd, int a)
 101 {
 102         return ioctl(fd, TCXONC, a);
 103 }
 104
 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
 115 static inline speed_t cfgetospeed(const struct termios *t)
 116 {
 117         return t->c_cflag & CBAUD;
 118 }
 119
 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
 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
 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 */
 160 static inline speed_t cfgetispeed(const struct termios *t)
 161 {
 162         return cfgetospeed(t);
 163 }
 164
 165 static inline int cfsetispeed(struct termios *t, speed_t s)
 166 {
 167         return cfsetospeed(t, s);
 168 }
 169 #endif /* !IBSHIFT */
 170
 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
 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_ */