tools: kwboot: Allow any baudrate on Linux

The A38x platform supports more baudrates than just those defined by the
Bn constants, and some of them are higher than the highest Bn baudrate
(the highest is 4 MBd while A38x support 5.15 MBd).

On Linux, add support for arbitrary baudrates. (Since there is no
standard POSIX API to specify arbitrary baudrate for a tty device, this
change is Linux-specific.)

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> (included by <sys/ioctl.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.

Note that the Bnnn constants from <termios.h> need not be compatible
with Bnnn constants from <asm/termbits.h>.

Signed-off-by: Pali Rohár <pali@kernel.org>
[ termios macros rewritten to static inline functions (for type control)
  and moved to tools/termios_linux.h ]
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Reviewed-by: Stefan Roese <sr@denx.de>

tools/kwboot.c

@@ -23,10 +23,15 @@
 #include <errno.h>
 #include <unistd.h>
 #include <stdint.h>
-#include <termios.h>
 #include <time.h>
 #include <sys/stat.h>
 
+#ifdef __linux__
+#include "termios_linux.h"
+#else
+#include <termios.h>
+#endif
+
 /*
  * Marvell BootROM UART Sensing
  */
@@ -554,7 +559,11 @@ kwboot_tty_baudrate_to_speed(int baudrate)
 		return B50;
 #endif
 	default:
+#ifdef BOTHER
+		return BOTHER;
+#else
 		return B0;
+#endif
 	}
 }
 
@@ -575,6 +584,11 @@ kwboot_tty_change_baudrate(int fd, int baudrate)
 		return -1;
 	}
 
+#ifdef BOTHER
+	if (speed == BOTHER)
+		tio.c_ospeed = tio.c_ispeed = baudrate;
+#endif
+
 	rc = cfsetospeed(&tio, speed);
 	if (rc)
 		return rc;

tools/termios_linux.h

@@ -0,0 +1,189 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * termios fuctions to support arbitrary baudrates (on Linux)
+ *
+ * Copyright (c) 2021 Pali Rohár <pali@kernel.org>
+ * Copyright (c) 2021 Marek Behún <marek.behun@nic.cz>
+ */
+
+#ifndef _TERMIOS_LINUX_H_
+#define _TERMIOS_LINUX_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>
+ * (included by <sys/ioctl.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/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)
+{
+	return ioctl(fd, TCSBRK, d);
+}
+
+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 /* _TERMIOS_LINUX_H_ */