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Date:      Wed, 12 Jun 2019 18:07:05 +0000 (UTC)
From:      Stephen Hurd <shurd@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r348999 - in head: bin/stty share/man/man4 sys/dev/uart sys/dev/usb/serial sys/kern sys/sys
Message-ID:  <201906121807.x5CI75jY085932@repo.freebsd.org>

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Author: shurd
Date: Wed Jun 12 18:07:04 2019
New Revision: 348999
URL: https://svnweb.freebsd.org/changeset/base/348999

Log:
  Some devices take undesired actions when RTS and DTR are
  asserted. Some development boards for example will reset on DTR,
  and some radio interfaces will transmit on RTS.
  
  This patch allows "stty -f /dev/ttyu9.init -rtsdtr" to prevent
  RTS and DTR from being asserted on open(), allowing these devices
  to be used without problems.
  
  Reviewed by:    imp
  Differential Revision:  https://reviews.freebsd.org/D20031

Modified:
  head/bin/stty/modes.c
  head/bin/stty/print.c
  head/bin/stty/stty.1
  head/share/man/man4/termios.4
  head/sys/dev/uart/uart_tty.c
  head/sys/dev/usb/serial/umcs.c
  head/sys/dev/usb/serial/usb_serial.c
  head/sys/kern/tty.c
  head/sys/sys/_termios.h

Modified: head/bin/stty/modes.c
==============================================================================
--- head/bin/stty/modes.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/bin/stty/modes.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -91,6 +91,8 @@ static const struct modes cmodes[] = {
 	{ "-rtsflow",	0, CRTS_IFLOW },
 	{ "mdmbuf",	MDMBUF, 0 },
 	{ "-mdmbuf",	0, MDMBUF },
+	{ "rtsdtr",	0, CNO_RTSDTR },
+	{ "-rtsdtr",	CNO_RTSDTR, 0 },
 	{ NULL,		0, 0 },
 };
 

Modified: head/bin/stty/print.c
==============================================================================
--- head/bin/stty/print.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/bin/stty/print.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -184,6 +184,12 @@ print(struct termios *tp, struct winsize *wp, int ldis
 	put("-dsrflow", CDSR_OFLOW, 0);
 	put("-dtrflow", CDTR_IFLOW, 0);
 	put("-mdmbuf", MDMBUF, 0);	/* XXX mdmbuf ==  dtrflow */
+	if (on(CNO_RTSDTR))
+		bput("-rtsdtr");
+	else {
+		if (fmt >= BSD)
+			bput("rtsdtr");
+	}
 
 	/* special control characters */
 	cc = tp->c_cc;

Modified: head/bin/stty/stty.1
==============================================================================
--- head/bin/stty/stty.1	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/bin/stty/stty.1	Wed Jun 12 18:07:04 2019	(r348999)
@@ -145,6 +145,8 @@ Assume a line without (with) modem
 control.
 .It Cm crtscts Pq Fl crtscts
 Enable (disable) RTS/CTS flow control.
+.It Cm rtsdtr Pq Fl -rtsdtr
+Enable (disable) asserting RTS/DTR on open.
 .El
 .Ss Input Modes:
 This corresponds to the c_iflag in the termios structure.

Modified: head/share/man/man4/termios.4
==============================================================================
--- head/share/man/man4/termios.4	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/share/man/man4/termios.4	Wed Jun 12 18:07:04 2019	(r348999)
@@ -1185,6 +1185,8 @@ flow control of output */
 /* RTS flow control of input */
 .It Dv MDMBUF
 /* flow control output via Carrier */
+.It Dv CNO_RTSDTR
+/* Do not assert RTS or DTR automatically */
 .El
 .Pp
 The
@@ -1266,6 +1268,12 @@ If
 .Dv MDMBUF
 is set then output flow control is controlled by the state
 of Carrier Detect.
+.Pp
+If
+.Dv CNO_RTSDTR
+is set then the RTS and DTR lines will not be asserted when the device
+is opened.
+As a result, this flag is only useful on initial-state devices.
 .Pp
 If the object for which the control modes are set is not an asynchronous
 serial connection, some of the modes may be ignored; for example, if an

Modified: head/sys/dev/uart/uart_tty.c
==============================================================================
--- head/sys/dev/uart/uart_tty.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/sys/dev/uart/uart_tty.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -285,13 +285,16 @@ uart_tty_param(struct tty *tp, struct termios *t)
 		parity = UART_PARITY_NONE;
 	if (UART_PARAM(sc, t->c_ospeed, databits, stopbits, parity) != 0)
 		return (EINVAL);
-	UART_SETSIG(sc, SER_DDTR | SER_DTR);
+	if ((t->c_cflag & CNO_RTSDTR) == 0)
+		UART_SETSIG(sc, SER_DDTR | SER_DTR);
 	/* Set input flow control state. */
 	if (!sc->sc_hwiflow) {
 		if ((t->c_cflag & CRTS_IFLOW) && sc->sc_isquelch)
 			UART_SETSIG(sc, SER_DRTS);
-		else
-			UART_SETSIG(sc, SER_DRTS | SER_RTS);
+		else {
+			if ((t->c_cflag & CNO_RTSDTR) == 0)
+				UART_SETSIG(sc, SER_DRTS | SER_RTS);
+		}
 	} else
 		UART_IOCTL(sc, UART_IOCTL_IFLOW, (t->c_cflag & CRTS_IFLOW));
 	/* Set output flow control state. */

Modified: head/sys/dev/usb/serial/umcs.c
==============================================================================
--- head/sys/dev/usb/serial/umcs.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/sys/dev/usb/serial/umcs.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -499,7 +499,9 @@ umcs7840_cfg_open(struct ucom_softc *ucom)
 	 * Enable DTR/RTS on modem control, enable modem interrupts --
 	 * documented
 	 */
-	sc->sc_ports[pn].sc_mcr = MCS7840_UART_MCR_DTR | MCS7840_UART_MCR_RTS | MCS7840_UART_MCR_IE;
+	sc->sc_ports[pn].sc_mcr = MCS7840_UART_MCR_IE;
+	if (ucom->sc_tty == NULL || (ucom->sc_tty->t_termios.c_cflag & CNO_RTSDTR) == 0)
+		sc->sc_ports[pn].sc_mcr |= MCS7840_UART_MCR_DTR | MCS7840_UART_MCR_RTS;
 	if (umcs7840_set_UART_reg_sync(sc, pn, MCS7840_UART_REG_MCR, sc->sc_ports[pn].sc_mcr))
 		return;
 

Modified: head/sys/dev/usb/serial/usb_serial.c
==============================================================================
--- head/sys/dev/usb/serial/usb_serial.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/sys/dev/usb/serial/usb_serial.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -796,7 +796,8 @@ ucom_open(struct tty *tp)
 	    &sc->sc_start_task[0].hdr, 
 	    &sc->sc_start_task[1].hdr);
 
-	ucom_modem(tp, SER_DTR | SER_RTS, 0);
+	if (sc->sc_tty == NULL || (sc->sc_tty->t_termios.c_cflag & CNO_RTSDTR) == 0)
+		ucom_modem(tp, SER_DTR | SER_RTS, 0);
 
 	ucom_ring(sc, 0);
 

Modified: head/sys/kern/tty.c
==============================================================================
--- head/sys/kern/tty.c	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/sys/kern/tty.c	Wed Jun 12 18:07:04 2019	(r348999)
@@ -93,7 +93,7 @@ static const char	*dev_console_filename;
 			FLUSHO|NOKERNINFO|NOFLSH)
 #define TTYSUP_CFLAG	(CIGNORE|CSIZE|CSTOPB|CREAD|PARENB|PARODD|\
 			HUPCL|CLOCAL|CCTS_OFLOW|CRTS_IFLOW|CDTR_IFLOW|\
-			CDSR_OFLOW|CCAR_OFLOW)
+			CDSR_OFLOW|CCAR_OFLOW|CNO_RTSDTR)
 
 #define	TTY_CALLOUT(tp,d) (dev2unit(d) & TTYUNIT_CALLOUT)
 
@@ -332,7 +332,8 @@ ttydev_open(struct cdev *dev, int oflags, int devtype 
 		if (TTY_CALLOUT(tp, dev) || dev == dev_console)
 			tp->t_termios.c_cflag |= CLOCAL;
 
-		ttydevsw_modem(tp, SER_DTR|SER_RTS, 0);
+		if ((tp->t_termios.c_cflag & CNO_RTSDTR) == 0)
+			ttydevsw_modem(tp, SER_DTR|SER_RTS, 0);
 
 		error = ttydevsw_open(tp);
 		if (error != 0)

Modified: head/sys/sys/_termios.h
==============================================================================
--- head/sys/sys/_termios.h	Wed Jun 12 16:49:01 2019	(r348998)
+++ head/sys/sys/_termios.h	Wed Jun 12 18:07:04 2019	(r348999)
@@ -143,6 +143,7 @@
 #define	CDTR_IFLOW	0x00040000	/* DTR flow control of input */
 #define	CDSR_OFLOW	0x00080000	/* DSR flow control of output */
 #define	CCAR_OFLOW	0x00100000	/* DCD flow control of output */
+#define	CNO_RTSDTR	0x00200000	/* Do not assert RTS or DTR automatically */
 #endif

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