4 files changed, 59 insertions, 52 deletions

diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 9191d05cfaf0..6e4ff7148ead 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -421,8 +421,11 @@ static void omap_8250_set_termios(struct uart_port *port,
 
         priv->efr = 0;
         up->mcr &= ~(UART_MCR_RTS | UART_MCR_XONANY);
+        up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
+
         if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
                 /* Enable AUTORTS and AUTOCTS */
+                up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
                 priv->efr |= UART_EFR_CTS | UART_EFR_RTS;
         } else  if (up->port.flags & UPF_SOFT_FLOW) {
                 /*
@@ -438,8 +441,10 @@ static void omap_8250_set_termios(struct uart_port *port,
                  * Enable XON/XOFF flow control on output.
                  * Transmit XON1, XOFF1
                  */
-                if (termios->c_iflag & IXOFF)
+                if (termios->c_iflag & IXOFF) {
+                        up->port.status |= UPSTAT_AUTOXOFF;
                         priv->efr |= OMAP_UART_SW_TX;
+                }
 
                 /*
                  * IXANY Flag:
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b1cf9a3b673a..6129fe515932 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1053,8 +1053,11 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 
         serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
 
+        up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
+
         if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
                 /* Enable AUTORTS and AUTOCTS */
+                up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
                 up->efr |= UART_EFR_CTS | UART_EFR_RTS;
 
                 /* Ensure MCR RTS is asserted */
@@ -1081,8 +1084,10 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
                  * Enable XON/XOFF flow control on output.
                  * Transmit XON1, XOFF1
                  */
-                if (termios->c_iflag & IXOFF)
+                if (termios->c_iflag & IXOFF) {
+                        up->port.status |= UPSTAT_AUTOXOFF;
                         up->efr |= OMAP_UART_SW_TX;
+                }
 
                 /*
                  * IXANY Flag:
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 2c67a077042a..6a1055ae3437 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -179,14 +179,6 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state,
                         if (tty->termios.c_cflag & CBAUD)
                                 uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
                 }
-
-                spin_lock_irq(&uport->lock);
-                if (uart_cts_enabled(uport) &&
-                    !(uport->ops->get_mctrl(uport) & TIOCM_CTS))
-                        uport->hw_stopped = 1;
-                else
-                        uport->hw_stopped = 0;
-                spin_unlock_irq(&uport->lock);
         }
 
         /*
@@ -442,6 +434,7 @@ static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
 {
         struct uart_port *uport = state->uart_port;
         struct ktermios *termios;
+        int hw_stopped;
 
         /*
          * If we have no tty, termios, or the port does not exist,
@@ -466,6 +459,18 @@ static void uart_change_speed(struct tty_struct *tty, struct uart_state *state,
                 uport->status &= ~UPSTAT_DCD_ENABLE;
         else
                 uport->status |= UPSTAT_DCD_ENABLE;
+
+        /* reset sw-assisted CTS flow control based on (possibly) new mode */
+        hw_stopped = uport->hw_stopped;
+        uport->hw_stopped = uart_softcts_mode(uport) &&
+                                !(uport->ops->get_mctrl(uport) & TIOCM_CTS);
+        if (uport->hw_stopped) {
+                if (!hw_stopped)
+                        uport->ops->stop_tx(uport);
+        } else {
+                if (hw_stopped)
+                        __uart_start(tty);
+        }
         spin_unlock_irq(&uport->lock);
 }
 
@@ -619,22 +624,22 @@ static void uart_throttle(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
         struct uart_port *port = state->uart_port;
-        upf_t mask = 0;
+        upstat_t mask = 0;
 
         if (I_IXOFF(tty))
-                mask |= UPF_SOFT_FLOW;
+                mask |= UPSTAT_AUTOXOFF;
         if (tty->termios.c_cflag & CRTSCTS)
-                mask |= UPF_HARD_FLOW;
+                mask |= UPSTAT_AUTORTS;
 
-        if (port->flags & mask) {
+        if (port->status & mask) {
                 port->ops->throttle(port);
-                mask &= ~port->flags;
+                mask &= ~port->status;
         }
 
-        if (mask & UPF_SOFT_FLOW)
+        if (mask & UPSTAT_AUTOXOFF)
                 uart_send_xchar(tty, STOP_CHAR(tty));
 
-        if (mask & UPF_HARD_FLOW)
+        if (mask & UPSTAT_AUTORTS)
                 uart_clear_mctrl(port, TIOCM_RTS);
 }
 
@@ -642,22 +647,22 @@ static void uart_unthrottle(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
         struct uart_port *port = state->uart_port;
-        upf_t mask = 0;
+        upstat_t mask = 0;
 
         if (I_IXOFF(tty))
-                mask |= UPF_SOFT_FLOW;
+                mask |= UPSTAT_AUTOXOFF;
         if (tty->termios.c_cflag & CRTSCTS)
-                mask |= UPF_HARD_FLOW;
+                mask |= UPSTAT_AUTORTS;
 
-        if (port->flags & mask) {
+        if (port->status & mask) {
                 port->ops->unthrottle(port);
-                mask &= ~port->flags;
+                mask &= ~port->status;
         }
 
-        if (mask & UPF_SOFT_FLOW)
+        if (mask & UPSTAT_AUTOXOFF)
                 uart_send_xchar(tty, START_CHAR(tty));
 
-        if (mask & UPF_HARD_FLOW)
+        if (mask & UPSTAT_AUTORTS)
                 uart_set_mctrl(port, TIOCM_RTS);
 }
 
@@ -1351,30 +1356,6 @@ static void uart_set_termios(struct tty_struct *tty,
                         mask |= TIOCM_RTS;
                 uart_set_mctrl(uport, mask);
         }
-
-        /*
-         * If the port is doing h/w assisted flow control, do nothing.
-         * We assume that port->hw_stopped has never been set.
-         */
-        if (uport->flags & UPF_HARD_FLOW)
-                return;
-
-        /* Handle turning off CRTSCTS */
-        if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {
-                spin_lock_irq(&uport->lock);
-                uport->hw_stopped = 0;
-                __uart_start(tty);
-                spin_unlock_irq(&uport->lock);
-        }
-        /* Handle turning on CRTSCTS */
-        else if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
-                spin_lock_irq(&uport->lock);
-                if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) {
-                        uport->hw_stopped = 1;
-                        uport->ops->stop_tx(uport);
-                }
-                spin_unlock_irq(&uport->lock);
-        }
 }
 
 /*
@@ -2855,7 +2836,7 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
 
         uport->icount.cts++;
 
-        if (uart_cts_enabled(uport)) {
+        if (uart_softcts_mode(uport)) {
                 if (uport->hw_stopped) {
                         if (status) {
                                 uport->hw_stopped = 0;
@@ -2868,6 +2849,7 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
                                 uport->ops->stop_tx(uport);
                         }
                 }
+
         }
 }
 EXPORT_SYMBOL_GPL(uart_handle_cts_change);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index a0c7033d5f91..baf3e1d08416 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -191,8 +191,10 @@ struct uart_port {
 #define UPF_NO_TXEN_TEST        ((__force upf_t) (1 << 15))
 #define UPF_MAGIC_MULTIPLIER    ((__force upf_t) ASYNC_MAGIC_MULTIPLIER /* 16 */ )
 
-/* Port has hardware-assisted h/w flow control (iow, auto-RTS *not* auto-CTS) */
-#define UPF_HARD_FLOW           ((__force upf_t) (1 << 21))
+/* Port has hardware-assisted h/w flow control */
+#define UPF_AUTO_CTS            ((__force upf_t) (1 << 20))
+#define UPF_AUTO_RTS            ((__force upf_t) (1 << 21))
+#define UPF_HARD_FLOW           ((__force upf_t) (UPF_AUTO_CTS | UPF_AUTO_RTS))
 /* Port has hardware-assisted s/w flow control */
 #define UPF_SOFT_FLOW           ((__force upf_t) (1 << 22))
 #define UPF_CONS_FLOW           ((__force upf_t) (1 << 23))
@@ -214,11 +216,17 @@ struct uart_port {
 #error Change mask not equivalent to userspace-visible bit defines
 #endif
 
-        /* status must be updated while holding port lock */
+        /*
+         * Must hold termios_rwsem, port mutex and port lock to change;
+         * can hold any one lock to read.
+         */
         upstat_t                status;
 
 #define UPSTAT_CTS_ENABLE       ((__force upstat_t) (1 << 0))
 #define UPSTAT_DCD_ENABLE       ((__force upstat_t) (1 << 1))
+#define UPSTAT_AUTORTS          ((__force upstat_t) (1 << 2))
+#define UPSTAT_AUTOCTS          ((__force upstat_t) (1 << 3))
+#define UPSTAT_AUTOXOFF         ((__force upstat_t) (1 << 4))
 
         int                     hw_stopped;             /* sw-assisted CTS flow state */
         unsigned int            mctrl;                  /* current modem ctrl settings */
@@ -392,6 +400,13 @@ static inline bool uart_cts_enabled(struct uart_port *uport)
         return !!(uport->status & UPSTAT_CTS_ENABLE);
 }
 
+static inline bool uart_softcts_mode(struct uart_port *uport)
+{
+        upstat_t mask = UPSTAT_CTS_ENABLE | UPSTAT_AUTOCTS;
+
+        return ((uport->status & mask) == UPSTAT_CTS_ENABLE);
+}
+
 /*
  * The following are helper functions for the low level drivers.
  */