/* SPDX-License-Identifier: GPL-2.0+ OR BSD-4-Clause OR BSD-3-Clause OR BSD-2-Clause */

/* SPDX-License-Identifier: GPL-2.0+ OR BSD-4-Clause OR BSD-3-Clause OR BSD-2-Clause */
/*
* termios fuctions to support arbitrary baudrates (on Linux)
*
* Copyright (c) 2021 Pali Rohár <[email protected]>
* Copyright (c) 2021 Marek Behún <[email protected]>
*/

#ifndef PPP_TERMIOS_LINUX_H
#define PPP_TERMIOS_LINUX_H

#include "pppdconf.h"

/*
* We need to use raw TCGETS2/TCSETS2 or TCGETS/TCSETS ioctls with the BOTHER
* flag in struct termios2/termios, defined in Linux headers <asm/ioctls.h>
* and <asm/termbits.h>. Since these headers conflict with glibc's header file
* <termios.h>, it is not possible to use libc's termios functions and we need
* to reimplement them via ioctl() calls.
*
* An arbitrary baudrate is supported when the macro BOTHER is defined. The
* baudrate value itself is then stored into the c_ospeed and c_ispeed members.
* If ioctls TCGETS2/TCSETS2 are defined and supported then these fields are
* present in struct termios2, otherwise these fields are present in struct
* termios.
*
* Note that the Bnnn constants from <termios.h> need not be compatible with
* Bnnn constants from <asm/termbits.h>.
*/

#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <asm/ioctls.h>
#include <asm/termbits.h>

#if defined(BOTHER) && defined(TCGETS2)
#define termios termios2
#endif

static inline int tcgetattr(int fd, struct termios *t)
{
#if defined(BOTHER) && defined(TCGETS2)
return ioctl(fd, TCGETS2, t);
#else
return ioctl(fd, TCGETS, t);
#endif
}

static inline int tcsetattr(int fd, int a, const struct termios *t)
{
int cmd;

switch (a) {
#if defined(BOTHER) && defined(TCGETS2)
case TCSANOW:
cmd = TCSETS2;
break;
case TCSADRAIN:
cmd = TCSETSW2;
break;
case TCSAFLUSH:
cmd = TCSETSF2;
break;
#else
case TCSANOW:
cmd = TCSETS;
break;
case TCSADRAIN:
cmd = TCSETSW;
break;
case TCSAFLUSH:
cmd = TCSETSF;
break;
#endif
default:
errno = EINVAL;
return -1;
}

return ioctl(fd, cmd, t);
}

static inline int tcdrain(int fd)
{
return ioctl(fd, TCSBRK, 1);
}

static inline int tcflush(int fd, int q)
{
return ioctl(fd, TCFLSH, q);
}

static inline int tcsendbreak(int fd, int d)
{
#ifdef TCSBRKP
return ioctl(fd, TCSBRKP, d);
#else
return ioctl(fd, TCSBRK, 0);
#endif
}

static inline int tcflow(int fd, int a)
{
return ioctl(fd, TCXONC, a);
}

static inline pid_t tcgetsid(int fd)
{
pid_t sid;

if (ioctl(fd, TIOCGSID, &sid) < 0)
return (pid_t)-1;

return sid;
}

static inline speed_t cfgetospeed(const struct termios *t)
{
return t->c_cflag & CBAUD;
}

static inline int cfsetospeed(struct termios *t, speed_t s)
{
if (s & ~CBAUD) {
errno = EINVAL;
return -1;
}

t->c_cflag &= ~CBAUD;
t->c_cflag |= s;

return 0;
}

#ifdef IBSHIFT
static inline speed_t cfgetispeed(const struct termios *t)
{
speed_t s = (t->c_cflag >> IBSHIFT) & CBAUD;

if (s == B0)
return cfgetospeed(t);
else
return s;
}

static inline int cfsetispeed(struct termios *t, speed_t s)
{
if (s == 0)
s = B0;

if (s & ~CBAUD) {
errno = EINVAL;
return -1;
}

t->c_cflag &= ~(CBAUD << IBSHIFT);
t->c_cflag |= s << IBSHIFT;

return 0;
}
#else /* !IBSHIFT */
static inline speed_t cfgetispeed(const struct termios *t)
{
return cfgetospeed(t);
}

static inline int cfsetispeed(struct termios *t, speed_t s)
{
return cfsetospeed(t, s);
}
#endif /* !IBSHIFT */

static inline int cfsetspeed(struct termios *t, speed_t s)
{
if (cfsetospeed(t, s))
return -1;
#ifdef IBSHIFT
if (cfsetispeed(t, s))
return -1;
#endif

return 0;
}

static void cfmakeraw(struct termios *t)
{
t->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR |
ICRNL | IXON);
t->c_oflag &= ~OPOST;
t->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
t->c_cflag &= ~(CSIZE | PARENB);
t->c_cflag |= CS8;
}

#endif /* PPP_TERMIOS_LINUX_H */