[PATCH u-boot-marvell 26/29] tools: kwboot: Allow any baudrate on Linux

[Marek Behún]

From: Pali Rohár <pali at kernel.org>

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> 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 at kernel.org>
[ termios macros rewritten to static inline functions (for type control)
  and moved to tools/termios.h ]
Signed-off-by: Marek Behún <marek.behun at nic.cz>
---
 tools/kwboot.c        |  16 +++-
 tools/termios_linux.h | 170 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 185 insertions(+), 1 deletion(-)
 create mode 100644 tools/termios_linux.h

diff --git a/tools/kwboot.c b/tools/kwboot.c
index dbe59833eb..f60cfd130e 100644
--- a/tools/kwboot.c
+++ b/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
  */
@@ -553,7 +558,11 @@ kwboot_tty_baudrate_to_speed(int baudrate)
 		return B50;
 #endif
 	default:
+#ifdef BOTHER
+		return BOTHER;
+#else
 		return B0;
+#endif
 	}
 }
 
@@ -574,6 +583,11 @@ 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;
diff --git a/tools/termios_linux.h b/tools/termios_linux.h
new file mode 100644
index 0000000000..1c4223afa7
--- /dev/null
+++ b/tools/termios_linux.h
@@ -0,0 +1,170 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * termios fuctions to support arbitrary baudrates (on Linux)
+ *
+ * Copyright (c) 2021 Pali Rohár <pali at kernel.org>
+ * Copyright (c) 2021 Marek Behún <marek.behun at 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> 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)
+{
+	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)
+{
+	t->c_cflag &= ~CBAUD;
+	t->c_cflag |= s;
+
+	return 0;
+}
+
+#ifdef IBSHIFT
+static inline speed_t cfgetispeed(const struct termios *t)
+{
+	return (t->c_cflag >> IBSHIFT) & CBAUD;
+}
+
+static inline int cfsetispeed(struct termios *t, speed_t s)
+{
+	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)
+{
+	cfsetospeed(t, s);
+#ifdef IBSHIFT
+	cfsetispeed(t, s);
+#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_ */
-- 
2.31.1