Attachment 315300 Details for Bug 445211 – [2/2] add support for DTR/DSR flow control

[patch] [2/2] add support for DTR/DSR flow control

dtrdsr.patch (text/plain), 9.33 KB, created by Aristeu Rozanski on 2008-08-28 21:17:49 UTC

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Creator: Aristeu Rozanski

Created: 2008-08-28 21:17:49 UTC

Size: 9.33 KB

patch

obsolete

>https://bugzilla.redhat.com/show_bug.cgi?id=445215
>
>8250: add support for DTR/DSR hardware flow control
>
>This patch adds support for DTR/DSR hardware flow control to 8250
>driver. The upstream version will differ from this one, since it'll
>take a bigger rework.
>
>Tested with success by the customer and by me on a serial P.O.S. printer.
>
>---
> drivers/serial/8250.c        |   16 ++++++-
> drivers/serial/serial_core.c |   98 ++++++++++++++++++++++++++++++++++++++++++-
> include/linux/serial_core.h  |   50 ++++++++++++++-------
> 3 files changed, 143 insertions(+), 21 deletions(-)
>
>--- tree.orig/drivers/serial/8250.c	2008-08-28 13:34:55.000000000 -0400
>+++ tree/drivers/serial/8250.c	2008-08-28 13:45:50.000000000 -0400
>@@ -1310,7 +1310,7 @@ static unsigned int check_modem_status(s
> 		if (status & UART_MSR_TERI)
> 			up->port.icount.rng++;
> 		if (status & UART_MSR_DDSR)
>-			up->port.icount.dsr++;
>+			uart_handle_dsr_change(&up->port, status & UART_MSR_DSR);
> 		if (status & UART_MSR_DDCD)
> 			uart_handle_dcd_change(&up->port, status & UART_MSR_DCD);
> 		if (status & UART_MSR_DCTS)
>@@ -1619,8 +1619,20 @@ static inline void wait_for_xmitr(struct
> 
> 	/* Wait up to 1s for flow control if necessary */
> 	if (up->port.flags & UPF_CONS_FLOW) {
>+		struct uart_info *info = up->port.info;
>+		unsigned int msr;
>+
> 		tmout = 1000000;
>-		while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) {
>+		while (--tmout) {
>+			msr = serial_in(up, UART_MSR);
>+
>+			if ((info->flags & UIF_CTS_FLOW) &&
>+			    (msr & UART_MSR_CTS))
>+				break;
>+			else if ((info->flags & UIF_DSR_FLOW) &&
>+				 (msr & UART_MSR_DSR))
>+ 				break;
>+
> 			udelay(1);
> 			touch_nmi_watchdog();
> 		}
>--- tree.orig/drivers/serial/serial_core.c	2008-08-28 13:34:55.000000000 -0400
>+++ tree/drivers/serial/serial_core.c	2008-08-28 13:45:50.000000000 -0400
>@@ -199,6 +199,13 @@ static int uart_startup(struct uart_stat
> 			spin_unlock_irq(&port->lock);
> 		}
> 
>+		if (info->flags & UIF_DSR_FLOW) {
>+			spin_lock_irq(&port->lock);
>+			if (!(port->ops->get_mctrl(port) & TIOCM_DSR))
>+				info->tty->hw_stopped = 1;
>+			spin_unlock_irq(&port->lock);
>+		}
>+
> 		info->flags |= UIF_INITIALIZED;
> 
> 		clear_bit(TTY_IO_ERROR, &info->tty->flags);
>@@ -591,6 +598,8 @@ static void uart_throttle(struct tty_str
> 
> 	if (tty->termios->c_cflag & CRTSCTS)
> 		uart_clear_mctrl(state->port, TIOCM_RTS);
>+	if (state->info->flags & UIF_DSR_FLOW)
>+		uart_clear_mctrl(state->port, TIOCM_DTR);
> }
> 
> static void uart_unthrottle(struct tty_struct *tty)
>@@ -607,6 +616,8 @@ static void uart_unthrottle(struct tty_s
> 
> 	if (tty->termios->c_cflag & CRTSCTS)
> 		uart_set_mctrl(port, TIOCM_RTS);
>+	if (state->info->flags & UIF_DSR_FLOW)
>+		uart_set_mctrl(port, TIOCM_DTR);
> }
> 
> static int uart_get_info(struct uart_state *state,
>@@ -1168,7 +1179,10 @@ static void uart_set_termios(struct tty_
> 		if (!(cflag & CRTSCTS) ||
> 		    !test_bit(TTY_THROTTLED, &tty->flags))
> 			mask |= TIOCM_RTS;
>-		uart_set_mctrl(state->port, mask);
>+		if (state->info->flags & UIF_DSR_FLOW)
>+			mask &= ~TIOCM_DTR;
>+		if (mask)
>+			uart_set_mctrl(state->port, mask);
> 	}
> 
> 	/* Handle turning off CRTSCTS */
>@@ -1182,6 +1196,7 @@ static void uart_set_termios(struct tty_
> 	/* Handle turning on CRTSCTS */
> 	if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
> 		spin_lock_irqsave(&state->port->lock, flags);
>+		state->port->info->flags &= ~UIF_DSR_FLOW;
> 		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
> 			tty->hw_stopped = 1;
> 			state->port->ops->stop_tx(state->port);
>@@ -1202,6 +1217,81 @@ static void uart_set_termios(struct tty_
> #endif
> }
> 
>+static void uart_set_termiox(struct tty_struct *tty, struct termiox *tnew)
>+{
>+	struct uart_state *state = tty->driver_data;
>+	long flags;
>+
>+	if ((tnew->x_cflag & (CTSXON | RTSXOFF)) == (CTSXON | RTSXOFF)) {
>+		/* Handle turning on CRTSCTS */
>+		spin_lock_irqsave(&state->port->lock, flags);
>+		tty->termios->c_cflag |= CRTSCTS;
>+		state->port->info->flags &= ~UIF_DSR_FLOW;
>+		state->port->info->flags |= UIF_CTS_FLOW;
>+
>+		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_CTS)) {
>+			tty->hw_stopped = 1;
>+			state->port->ops->stop_tx(state->port);
>+		} else if (tty->hw_stopped) {
>+			tty->hw_stopped = 0;
>+			__uart_start(tty);
>+		}
>+		spin_unlock_irqrestore(&state->port->lock, flags);
>+
>+		uart_clear_mctrl(state->port, TIOCM_RTS | TIOCM_DTR);
>+
>+		if (tty->termios->c_cflag & CBAUD) {
>+			unsigned int mask = TIOCM_DTR;
>+
>+			if (!test_bit(TTY_THROTTLED, &tty->flags))
>+				mask |= TIOCM_RTS;
>+			uart_set_mctrl(state->port, mask);
>+		}
>+	} else if ((tnew->x_cflag & (DSRXON | DTRXOFF)) == (DSRXON | DTRXOFF)) {
>+		spin_lock_irqsave(&state->port->lock, flags);
>+		tty->termios->c_cflag &= ~CRTSCTS;
>+		state->port->info->flags &= ~UIF_CTS_FLOW;
>+		state->port->info->flags |= UIF_DSR_FLOW;
>+
>+		if (!(state->port->ops->get_mctrl(state->port) & TIOCM_DSR)) {
>+			tty->hw_stopped = 1;
>+			state->port->ops->stop_tx(state->port);
>+		} else if (tty->hw_stopped) {
>+			tty->hw_stopped = 0;
>+			__uart_start(tty);
>+		}
>+		spin_unlock_irqrestore(&state->port->lock, flags);
>+
>+		uart_clear_mctrl(state->port, TIOCM_RTS | TIOCM_DTR);
>+
>+		if (tty->termios->c_cflag & CBAUD)
>+			uart_set_mctrl(state->port, TIOCM_DTR);
>+	} else if (!(tnew->x_cflag & (CTSXON | RTSXOFF | DSRXON | DTRXOFF))) {
>+		/* disabling flow control */
>+		spin_lock_irqsave(&state->port->lock, flags);
>+		tty->termios->c_cflag &= ~CRTSCTS;
>+		state->port->info->flags &= ~UIF_CTS_FLOW;
>+		state->port->info->flags &= ~UIF_DSR_FLOW;
>+
>+		tty->hw_stopped = 0;
>+		__uart_start(tty);
>+		spin_unlock_irqrestore(&state->port->lock, flags);
>+
>+		uart_clear_mctrl(state->port, TIOCM_RTS);
>+		uart_set_mctrl(state->port, TIOCM_DTR);
>+	}
>+}
>+
>+static void uart_get_termiox(struct tty_struct *tty, struct termiox *t)
>+{
>+	struct uart_state *state = tty->driver_data;
>+
>+	if (state->info->flags & UIF_CTS_FLOW)
>+		t->x_cflag = CTSXON | RTSXOFF;
>+	else if (state->info->flags & UIF_DSR_FLOW)
>+		t->x_cflag = DSRXON | DTRXOFF;
>+}
>+
> /*
>  * In 2.4.5, calls to this will be serialized via the BKL in
>  *  linux/drivers/char/tty_io.c:tty_release()
>@@ -1468,7 +1558,8 @@ uart_block_til_ready(struct file *filp, 
> 		 * not set RTS here - we want to make sure we catch
> 		 * the data from the modem.
> 		 */
>-		if (info->tty->termios->c_cflag & CBAUD)
>+		if (info->tty->termios->c_cflag & CBAUD &&
>+		    !(info->flags & UIF_DSR_FLOW))
> 			uart_set_mctrl(port, TIOCM_DTR);
> 
> 		/*
>@@ -2183,6 +2274,7 @@ int uart_register_driver(struct uart_dri
> 	normal->flags		= TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
> 	normal->driver_state    = drv;
> 	tty_set_operations(normal, &uart_ops);
>+	tty_register_termiox_handler(normal, uart_get_termiox, uart_set_termiox);
> 
> 	/*
> 	 * Initialise the UART state(s).
>@@ -2217,7 +2309,9 @@ int uart_register_driver(struct uart_dri
> void uart_unregister_driver(struct uart_driver *drv)
> {
> 	struct tty_driver *p = drv->tty_driver;
>+
> 	tty_unregister_driver(p);
>+	tty_unregister_termiox_handler(p);
> 	put_tty_driver(p);
> 	kfree(drv->state);
> 	drv->tty_driver = NULL;
>--- tree.orig/include/linux/serial_core.h	2008-08-28 13:34:55.000000000 -0400
>+++ tree/include/linux/serial_core.h	2008-08-28 13:45:50.000000000 -0400
>@@ -315,6 +315,7 @@ struct uart_info {
>  * Definitions for info->flags.  These are _private_ to serial_core, and
>  * are specific to this structure.  They may be queried by low level drivers.
>  */
>+#define UIF_DSR_FLOW		((__force uif_t) (1 << 24))
> #define UIF_CHECK_CD		((__force uif_t) (1 << 25))
> #define UIF_CTS_FLOW		((__force uif_t) (1 << 26))
> #define UIF_NORMAL_ACTIVE	((__force uif_t) (1 << 29))
>@@ -474,34 +475,48 @@ uart_handle_dcd_change(struct uart_port 
> }
> 
> /**
>- *	uart_handle_cts_change - handle a change of clear-to-send state
>+ *	uart_handle_flow_control_change - handle a change of CTS or DSR
>  *	@port: uart_port structure for the open port
>- *	@status: new clear to send status, nonzero if active
>+ *	@status: new CTS/DTR status, nonzero if active
>  */
> static inline void
>-uart_handle_cts_change(struct uart_port *port, unsigned int status)
>+uart_handle_flow_control_change(struct uart_port *port, unsigned int status)
> {
> 	struct uart_info *info = port->info;
> 	struct tty_struct *tty = info->tty;
> 
>-	port->icount.cts++;
>-
>-	if (info->flags & UIF_CTS_FLOW) {
>-		if (tty->hw_stopped) {
>-			if (status) {
>-				tty->hw_stopped = 0;
>-				port->ops->start_tx(port);
>-				uart_write_wakeup(port);
>-			}
>-		} else {
>-			if (!status) {
>-				tty->hw_stopped = 1;
>-				port->ops->stop_tx(port);
>-			}
>+	if (tty->hw_stopped) {
>+		if (status) {
>+			tty->hw_stopped = 0;
>+			port->ops->start_tx(port);
>+			uart_write_wakeup(port);
>+		}
>+	} else {
>+		if (!status) {
>+			tty->hw_stopped = 1;
>+			port->ops->stop_tx(port);
> 		}
> 	}
> }
> 
>+static inline void
>+uart_handle_cts_change(struct uart_port *port, unsigned int status)
>+{
>+	struct uart_info *info = port->info;
>+	port->icount.cts++;
>+	if (info->flags & UIF_CTS_FLOW)
>+		uart_handle_flow_control_change(port, status);
>+}
>+
>+static inline void
>+uart_handle_dsr_change(struct uart_port *port, unsigned int status)
>+{
>+	struct uart_info *info = port->info;
>+	port->icount.dsr++;
>+	if (info->flags & UIF_DSR_FLOW)
>+		uart_handle_flow_control_change(port, status);
>+}
>+
> #include <linux/tty_flip.h>
> 
> static inline void
>@@ -526,6 +541,7 @@ uart_insert_char(struct uart_port *port,
>  */
> #define UART_ENABLE_MS(port,cflag)	((port)->flags & UPF_HARDPPS_CD || \
> 					 (cflag) & CRTSCTS || \
>+					 ((port)->info && ((port)->info->flags & UIF_DSR_FLOW)) || \
> 					 !((cflag) & CLOCAL))
> 
> #endif

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Attachments on bug 445211: 308359 | 308360 | 309219 | 309849 | 315299 | 315300 | 315301