Merge branch 'omap-serial' of git://git.linaro.org/people/rmk/linux-arm

Pull ARM OMAP serial updates from Russell King:
 "This series is a major reworking of the OMAP serial driver code fixing
  various bugs in the hardware-assisted flow control, extending up into
  serial_core for a couple of issues.  These fixes have been done as a
  set of progressive changes and transformations in the hope that no new
  bugs will be introduced by this series.

  The problems are many-fold, from the driver not being informed about
  updated settings, to the driver not knowing what the intentions of the
  upper layers are.

  The first four patches tackle the serial_core layer, allowing it to
  provide the necessary information to drivers, and the remaining
  patches allow the OMAP serial driver to take advantage of this.

  This brings hardware assisted RTS/CTS and XON/OFF flow control into a
  useful state.

  These patches have been in linux-next for most of the last cycle;
  indeed they predate the previous merge window.  They've also been
  posted to the OMAP people."

* 'omap-serial' of git://git.linaro.org/people/rmk/linux-arm: (21 commits)
  SERIAL: omap: fix hardware assisted flow control
  SERIAL: omap: simplify (2)
  SERIAL: omap: move xon/xoff setting earlier
  SERIAL: omap: always set TCR
  SERIAL: omap: simplify
  SERIAL: omap: don't read back LCR/MCR/EFR
  SERIAL: omap: serial_omap_configure_xonxoff() contents into set_termios
  SERIAL: omap: configure xon/xoff before setting modem control lines
  SERIAL: omap: remove OMAP_UART_SYSC_RESET and OMAP_UART_FIFO_CLR
  SERIAL: omap: move driver private definitions and structures to driver
  SERIAL: omap: remove 'irq_pending' bitfield
  SERIAL: omap: fix MCR TCRTLR bit handling
  SERIAL: omap: fix set_mctrl() breakage
  SERIAL: omap: no need to re-read EFR
  SERIAL: omap: remove setting of EFR SCD bit
  SERIAL: omap: allow hardware assisted IXANY mode to be disabled
  SERIAL: omap: allow hardware assisted rts/cts modes to be disabled
  SERIAL: core: add throttle/unthrottle callbacks for hardware assisted flow control
  SERIAL: core: add hardware assisted h/w flow control support
  SERIAL: core: add hardware assisted s/w flow control support
  ...

Conflicts:
	drivers/tty/serial/omap-serial.c

4 files changed, 213 insertions, 150 deletions

diff --git a/arch/arm/plat-omap/include/plat/omap-serial.h b/arch/arm/plat-omap/include/plat/omap-serial.h
index 1957a8516e9..ff9b0aab528 100644
--- a/arch/arm/plat-omap/include/plat/omap-serial.h
+++ b/arch/arm/plat-omap/include/plat/omap-serial.h
@@ -30,35 +30,6 @@
  */
 #define OMAP_SERIAL_NAME        "ttyO"
 
-#define OMAP_MODE13X_SPEED      230400
-
-#define OMAP_UART_SCR_TX_EMPTY  0x08
-
-/* WER = 0x7F
- * Enable module level wakeup in WER reg
- */
-#define OMAP_UART_WER_MOD_WKUP  0X7F
-
-/* Enable XON/XOFF flow control on output */
-#define OMAP_UART_SW_TX         0x04
-
-/* Enable XON/XOFF flow control on input */
-#define OMAP_UART_SW_RX         0x04
-
-#define OMAP_UART_SYSC_RESET    0X07
-#define OMAP_UART_TCR_TRIG      0X0F
-#define OMAP_UART_SW_CLR        0XF0
-#define OMAP_UART_FIFO_CLR      0X06
-
-#define OMAP_UART_DMA_CH_FREE   -1
-
-#define OMAP_MAX_HSUART_PORTS   6
-
-#define MSR_SAVE_FLAGS          UART_MSR_ANY_DELTA
-
-#define UART_ERRATA_i202_MDR1_ACCESS    BIT(0)
-#define UART_ERRATA_i291_DMA_FORCEIDLE  BIT(1)
-
 struct omap_uart_port_info {
         bool                    dma_enabled;    /* To specify DMA Mode */
         unsigned int            uartclk;        /* UART clock rate */
@@ -77,30 +48,4 @@ struct omap_uart_port_info {
         void (*enable_wakeup)(struct device *, bool);
 };
 
-struct uart_omap_dma {
-        u8                      uart_dma_tx;
-        u8                      uart_dma_rx;
-        int                     rx_dma_channel;
-        int                     tx_dma_channel;
-        dma_addr_t              rx_buf_dma_phys;
-        dma_addr_t              tx_buf_dma_phys;
-        unsigned int            uart_base;
-        /*
-         * Buffer for rx dma.It is not required for tx because the buffer
-         * comes from port structure.
-         */
-        unsigned char           *rx_buf;
-        unsigned int            prev_rx_dma_pos;
-        int                     tx_buf_size;
-        int                     tx_dma_used;
-        int                     rx_dma_used;
-        spinlock_t              tx_lock;
-        spinlock_t              rx_lock;
-        /* timer to poll activity on rx dma */
-        struct timer_list       rx_timer;
-        unsigned int            rx_buf_size;
-        unsigned int            rx_poll_rate;
-        unsigned int            rx_timeout;
-};
-
 #endif /* __OMAP_SERIAL_H__ */
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b538e2e4ae5..23f797eb7a2 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -44,6 +44,8 @@
 
 #include <plat/omap-serial.h>
 
+#define OMAP_MAX_HSUART_PORTS   6
+
 #define UART_BUILD_REVISION(x, y)       (((x) << 8) | (y))
 
 #define OMAP_UART_REV_42 0x0402
@@ -51,10 +53,14 @@
 #define OMAP_UART_REV_52 0x0502
 #define OMAP_UART_REV_63 0x0603
 
+#define UART_ERRATA_i202_MDR1_ACCESS    BIT(0)
+#define UART_ERRATA_i291_DMA_FORCEIDLE  BIT(1)
+
 #define DEFAULT_CLK_SPEED 48000000 /* 48Mhz*/
 
 /* SCR register bitmasks */
 #define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK               (1 << 7)
+#define OMAP_UART_SCR_TX_EMPTY                  (1 << 3)
 
 /* FCR register bitmasks */
 #define OMAP_UART_FCR_RX_FIFO_TRIG_MASK                 (0x3 << 6)
@@ -71,6 +77,52 @@
 #define OMAP_UART_MVR_MAJ_SHIFT         8
 #define OMAP_UART_MVR_MIN_MASK          0x3f
 
+#define OMAP_UART_DMA_CH_FREE   -1
+
+#define MSR_SAVE_FLAGS          UART_MSR_ANY_DELTA
+#define OMAP_MODE13X_SPEED      230400
+
+/* WER = 0x7F
+ * Enable module level wakeup in WER reg
+ */
+#define OMAP_UART_WER_MOD_WKUP  0X7F
+
+/* Enable XON/XOFF flow control on output */
+#define OMAP_UART_SW_TX         0x08
+
+/* Enable XON/XOFF flow control on input */
+#define OMAP_UART_SW_RX         0x02
+
+#define OMAP_UART_SW_CLR        0xF0
+
+#define OMAP_UART_TCR_TRIG      0x0F
+
+struct uart_omap_dma {
+        u8                      uart_dma_tx;
+        u8                      uart_dma_rx;
+        int                     rx_dma_channel;
+        int                     tx_dma_channel;
+        dma_addr_t              rx_buf_dma_phys;
+        dma_addr_t              tx_buf_dma_phys;
+        unsigned int            uart_base;
+        /*
+         * Buffer for rx dma.It is not required for tx because the buffer
+         * comes from port structure.
+         */
+        unsigned char           *rx_buf;
+        unsigned int            prev_rx_dma_pos;
+        int                     tx_buf_size;
+        int                     tx_dma_used;
+        int                     rx_dma_used;
+        spinlock_t              tx_lock;
+        spinlock_t              rx_lock;
+        /* timer to poll activity on rx dma */
+        struct timer_list       rx_timer;
+        unsigned int            rx_buf_size;
+        unsigned int            rx_poll_rate;
+        unsigned int            rx_timeout;
+};
+
 struct uart_omap_port {
         struct uart_port        port;
         struct uart_omap_dma    uart_dma;
@@ -99,7 +151,6 @@ struct uart_omap_port {
         int                     context_loss_cnt;
         u32                     errata;
         u8                      wakeups_enabled;
-        unsigned int            irq_pending:1;
 
         int                     DTR_gpio;
         int                     DTR_inverted;
@@ -303,6 +354,34 @@ static void serial_omap_start_tx(struct uart_port *port)
         pm_runtime_put_autosuspend(up->dev);
 }
 
+static void serial_omap_throttle(struct uart_port *port)
+{
+        struct uart_omap_port *up = to_uart_omap_port(port);
+        unsigned long flags;
+
+        pm_runtime_get_sync(up->dev);
+        spin_lock_irqsave(&up->port.lock, flags);
+        up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
+        serial_out(up, UART_IER, up->ier);
+        spin_unlock_irqrestore(&up->port.lock, flags);
+        pm_runtime_mark_last_busy(up->dev);
+        pm_runtime_put_autosuspend(up->dev);
+}
+
+static void serial_omap_unthrottle(struct uart_port *port)
+{
+        struct uart_omap_port *up = to_uart_omap_port(port);
+        unsigned long flags;
+
+        pm_runtime_get_sync(up->dev);
+        spin_lock_irqsave(&up->port.lock, flags);
+        up->ier |= UART_IER_RLSI | UART_IER_RDI;
+        serial_out(up, UART_IER, up->ier);
+        spin_unlock_irqrestore(&up->port.lock, flags);
+        pm_runtime_mark_last_busy(up->dev);
+        pm_runtime_put_autosuspend(up->dev);
+}
+
 static unsigned int check_modem_status(struct uart_omap_port *up)
 {
         unsigned int status;
@@ -504,7 +583,7 @@ static unsigned int serial_omap_get_mctrl(struct uart_port *port)
 static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
         struct uart_omap_port *up = to_uart_omap_port(port);
-        unsigned char mcr = 0;
+        unsigned char mcr = 0, old_mcr;
 
         dev_dbg(up->port.dev, "serial_omap_set_mctrl+%d\n", up->port.line);
         if (mctrl & TIOCM_RTS)
@@ -519,8 +598,10 @@ static void serial_omap_set_mctrl(struct uart_port *port, unsigned int mctrl)
                 mcr |= UART_MCR_LOOP;
 
         pm_runtime_get_sync(up->dev);
-        up->mcr = serial_in(up, UART_MCR);
-        up->mcr |= mcr;
+        old_mcr = serial_in(up, UART_MCR);
+        old_mcr &= ~(UART_MCR_LOOP | UART_MCR_OUT2 | UART_MCR_OUT1 |
+                     UART_MCR_DTR | UART_MCR_RTS);
+        up->mcr = old_mcr | mcr;
         serial_out(up, UART_MCR, up->mcr);
         pm_runtime_mark_last_busy(up->dev);
         pm_runtime_put_autosuspend(up->dev);
@@ -654,61 +735,6 @@ static void serial_omap_shutdown(struct uart_port *port)
         free_irq(up->port.irq, up);
 }
 
-static inline void
-serial_omap_configure_xonxoff
-                (struct uart_omap_port *up, struct ktermios *termios)
-{
-        up->lcr = serial_in(up, UART_LCR);
-        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-        up->efr = serial_in(up, UART_EFR);
-        serial_out(up, UART_EFR, up->efr & ~UART_EFR_ECB);
-
-        serial_out(up, UART_XON1, termios->c_cc[VSTART]);
-        serial_out(up, UART_XOFF1, termios->c_cc[VSTOP]);
-
-        /* clear SW control mode bits */
-        up->efr &= OMAP_UART_SW_CLR;
-
-        /*
-         * IXON Flag:
-         * Enable XON/XOFF flow control on output.
-         * Transmit XON1, XOFF1
-         */
-        if (termios->c_iflag & IXON)
-                up->efr |= OMAP_UART_SW_TX;
-
-        /*
-         * IXOFF Flag:
-         * Enable XON/XOFF flow control on input.
-         * Receiver compares XON1, XOFF1.
-         */
-        if (termios->c_iflag & IXOFF)
-                up->efr |= OMAP_UART_SW_RX;
-
-        serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
-        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
-
-        up->mcr = serial_in(up, UART_MCR);
-
-        /*
-         * IXANY Flag:
-         * Enable any character to restart output.
-         * Operation resumes after receiving any
-         * character after recognition of the XOFF character
-         */
-        if (termios->c_iflag & IXANY)
-                up->mcr |= UART_MCR_XONANY;
-
-        serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
-        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-        serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
-
-        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
-
-        serial_out(up, UART_MCR, up->mcr & ~UART_MCR_TCRTLR);
-        serial_out(up, UART_LCR, up->lcr);
-}
-
 static void serial_omap_uart_qos_work(struct work_struct *work)
 {
         struct uart_omap_port *up = container_of(work, struct uart_omap_port,
@@ -726,7 +752,6 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 {
         struct uart_omap_port *up = to_uart_omap_port(port);
         unsigned char cval = 0;
-        unsigned char efr = 0;
         unsigned long flags = 0;
         unsigned int baud, quot;
 
@@ -836,11 +861,12 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 
         serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
 
-        up->efr = serial_in(up, UART_EFR);
+        up->efr = serial_in(up, UART_EFR) & ~UART_EFR_ECB;
+        up->efr &= ~UART_EFR_SCD;
         serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
 
         serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
-        up->mcr = serial_in(up, UART_MCR);
+        up->mcr = serial_in(up, UART_MCR) & ~UART_MCR_TCRTLR;
         serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
         /* FIFO ENABLE, DMA MODE */
 
@@ -859,9 +885,12 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
 
         serial_out(up, UART_OMAP_SCR, up->scr);
 
-        serial_out(up, UART_EFR, up->efr);
+        /* Reset UART_MCR_TCRTLR: this must be done with the EFR_ECB bit set */
         serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
         serial_out(up, UART_MCR, up->mcr);
+        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+        serial_out(up, UART_EFR, up->efr);
+        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
 
         /* Protocol, Baud Rate, and Interrupt Settings */
 
@@ -871,8 +900,6 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
                 serial_out(up, UART_OMAP_MDR1, up->mdr1);
 
         serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-
-        up->efr = serial_in(up, UART_EFR);
         serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
 
         serial_out(up, UART_LCR, 0);
@@ -899,29 +926,68 @@ serial_omap_set_termios(struct uart_port *port, struct ktermios *termios,
         else
                 serial_out(up, UART_OMAP_MDR1, up->mdr1);
 
-        /* Hardware Flow Control Configuration */
+        /* Configure flow control */
+        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+        /* XON1/XOFF1 accessible mode B, TCRTLR=0, ECB=0 */
+        serial_out(up, UART_XON1, termios->c_cc[VSTART]);
+        serial_out(up, UART_XOFF1, termios->c_cc[VSTOP]);
+
+        /* Enable access to TCR/TLR */
+        serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
+        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+        serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
+
+        serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
+
+        if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
+                /* Enable AUTORTS and AUTOCTS */
+                up->efr |= UART_EFR_CTS | UART_EFR_RTS;
+
+                /* Ensure MCR RTS is asserted */
+                up->mcr |= UART_MCR_RTS;
+        } else {
+                /* Disable AUTORTS and AUTOCTS */
+                up->efr &= ~(UART_EFR_CTS | UART_EFR_RTS);
+        }
 
-        if (termios->c_cflag & CRTSCTS) {
-                efr |= (UART_EFR_CTS | UART_EFR_RTS);
-                serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+        if (up->port.flags & UPF_SOFT_FLOW) {
+                /* clear SW control mode bits */
+                up->efr &= OMAP_UART_SW_CLR;
 
-                up->mcr = serial_in(up, UART_MCR);
-                serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
+                /*
+                 * IXON Flag:
+                 * Enable XON/XOFF flow control on input.
+                 * Receiver compares XON1, XOFF1.
+                 */
+                if (termios->c_iflag & IXON)
+                        up->efr |= OMAP_UART_SW_RX;
 
-                serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
-                up->efr = serial_in(up, UART_EFR);
-                serial_out(up, UART_EFR, up->efr | UART_EFR_ECB);
+                /*
+                 * IXOFF Flag:
+                 * Enable XON/XOFF flow control on output.
+                 * Transmit XON1, XOFF1
+                 */
+                if (termios->c_iflag & IXOFF)
+                        up->efr |= OMAP_UART_SW_TX;
 
-                serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
-                serial_out(up, UART_EFR, efr); /* Enable AUTORTS and AUTOCTS */
-                serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
-                serial_out(up, UART_MCR, up->mcr | UART_MCR_RTS);
-                serial_out(up, UART_LCR, cval);
+                /*
+                 * IXANY Flag:
+                 * Enable any character to restart output.
+                 * Operation resumes after receiving any
+                 * character after recognition of the XOFF character
+                 */
+                if (termios->c_iflag & IXANY)
+                        up->mcr |= UART_MCR_XONANY;
+                else
+                        up->mcr &= ~UART_MCR_XONANY;
         }
+        serial_out(up, UART_MCR, up->mcr);
+        serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+        serial_out(up, UART_EFR, up->efr);
+        serial_out(up, UART_LCR, up->lcr);
 
         serial_omap_set_mctrl(&up->port, up->port.mctrl);
-        /* Software Flow Control Configuration */
-        serial_omap_configure_xonxoff(up, termios);
 
         spin_unlock_irqrestore(&up->port.lock, flags);
         pm_runtime_mark_last_busy(up->dev);
@@ -987,6 +1053,7 @@ static void serial_omap_config_port(struct uart_port *port, int flags)
         dev_dbg(up->port.dev, "serial_omap_config_port+%d\n",
                                                         up->port.line);
         up->port.type = PORT_OMAP;
+        up->port.flags |= UPF_SOFT_FLOW | UPF_HARD_FLOW;
 }
 
 static int
@@ -1190,6 +1257,8 @@ static struct uart_ops serial_omap_pops = {
         .get_mctrl      = serial_omap_get_mctrl,
         .stop_tx        = serial_omap_stop_tx,
         .start_tx       = serial_omap_start_tx,
+        .throttle       = serial_omap_throttle,
+        .unthrottle     = serial_omap_unthrottle,
         .stop_rx        = serial_omap_stop_rx,
         .enable_ms      = serial_omap_enable_ms,
         .break_ctl      = serial_omap_break_ctl,
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index fb5aa42fde7..2c7230aaefd 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -610,27 +610,50 @@ static void uart_send_xchar(struct tty_struct *tty, char ch)
 static void uart_throttle(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
+        struct uart_port *port = state->uart_port;
+        uint32_t mask = 0;
 
         if (I_IXOFF(tty))
+                mask |= UPF_SOFT_FLOW;
+        if (tty->termios.c_cflag & CRTSCTS)
+                mask |= UPF_HARD_FLOW;
+
+        if (port->flags & mask) {
+                port->ops->throttle(port);
+                mask &= ~port->flags;
+        }
+
+        if (mask & UPF_SOFT_FLOW)
                 uart_send_xchar(tty, STOP_CHAR(tty));
 
-        if (tty->termios.c_cflag & CRTSCTS)
-                uart_clear_mctrl(state->uart_port, TIOCM_RTS);
+        if (mask & UPF_HARD_FLOW)
+                uart_clear_mctrl(port, TIOCM_RTS);
 }
 
 static void uart_unthrottle(struct tty_struct *tty)
 {
         struct uart_state *state = tty->driver_data;
         struct uart_port *port = state->uart_port;
+        uint32_t mask = 0;
 
-        if (I_IXOFF(tty)) {
+        if (I_IXOFF(tty))
+                mask |= UPF_SOFT_FLOW;
+        if (tty->termios.c_cflag & CRTSCTS)
+                mask |= UPF_HARD_FLOW;
+
+        if (port->flags & mask) {
+                port->ops->unthrottle(port);
+                mask &= ~port->flags;
+        }
+
+        if (mask & UPF_SOFT_FLOW) {
                 if (port->x_char)
                         port->x_char = 0;
                 else
                         uart_send_xchar(tty, START_CHAR(tty));
         }
 
-        if (tty->termios.c_cflag & CRTSCTS)
+        if (mask & UPF_HARD_FLOW)
                 uart_set_mctrl(port, TIOCM_RTS);
 }
 
@@ -1214,9 +1237,22 @@ static void uart_set_termios(struct tty_struct *tty,
                                                 struct ktermios *old_termios)
 {
         struct uart_state *state = tty->driver_data;
+        struct uart_port *uport = state->uart_port;
         unsigned long flags;
         unsigned int cflag = tty->termios.c_cflag;
+        unsigned int iflag_mask = IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK;
+        bool sw_changed = false;
 
+        /*
+         * Drivers doing software flow control also need to know
+         * about changes to these input settings.
+         */
+        if (uport->flags & UPF_SOFT_FLOW) {
+                iflag_mask |= IXANY|IXON|IXOFF;
+                sw_changed =
+                   tty->termios.c_cc[VSTART] != old_termios->c_cc[VSTART] ||
+                   tty->termios.c_cc[VSTOP] != old_termios->c_cc[VSTOP];
+        }
 
         /*
          * These are the bits that are used to setup various
@@ -1224,11 +1260,11 @@ static void uart_set_termios(struct tty_struct *tty,
          * bits in c_cflag; c_[io]speed will always be set
          * appropriately by set_termios() in tty_ioctl.c
          */
-#define RELEVANT_IFLAG(iflag)   ((iflag) & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
         if ((cflag ^ old_termios->c_cflag) == 0 &&
             tty->termios.c_ospeed == old_termios->c_ospeed &&
             tty->termios.c_ispeed == old_termios->c_ispeed &&
-            RELEVANT_IFLAG(tty->termios.c_iflag ^ old_termios->c_iflag) == 0) {
+            ((tty->termios.c_iflag ^ old_termios->c_iflag) & iflag_mask) == 0 &&
+            !sw_changed) {
                 return;
         }
 
@@ -1236,31 +1272,38 @@ static void uart_set_termios(struct tty_struct *tty,
 
         /* Handle transition to B0 status */
         if ((old_termios->c_cflag & CBAUD) && !(cflag & CBAUD))
-                uart_clear_mctrl(state->uart_port, TIOCM_RTS | TIOCM_DTR);
+                uart_clear_mctrl(uport, TIOCM_RTS | TIOCM_DTR);
         /* Handle transition away from B0 status */
         else if (!(old_termios->c_cflag & CBAUD) && (cflag & CBAUD)) {
                 unsigned int mask = TIOCM_DTR;
                 if (!(cflag & CRTSCTS) ||
                     !test_bit(TTY_THROTTLED, &tty->flags))
                         mask |= TIOCM_RTS;
-                uart_set_mctrl(state->uart_port, mask);
+                uart_set_mctrl(uport, mask);
         }
 
+        /*
+         * If the port is doing h/w assisted flow control, do nothing.
+         * We assume that tty->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_irqsave(&state->uart_port->lock, flags);
+                spin_lock_irqsave(&uport->lock, flags);
                 tty->hw_stopped = 0;
                 __uart_start(tty);
-                spin_unlock_irqrestore(&state->uart_port->lock, flags);
+                spin_unlock_irqrestore(&uport->lock, flags);
         }
         /* Handle turning on CRTSCTS */
         else if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {
-                spin_lock_irqsave(&state->uart_port->lock, flags);
-                if (!(state->uart_port->ops->get_mctrl(state->uart_port) & TIOCM_CTS)) {
+                spin_lock_irqsave(&uport->lock, flags);
+                if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) {
                         tty->hw_stopped = 1;
-                        state->uart_port->ops->stop_tx(state->uart_port);
+                        uport->ops->stop_tx(uport);
                 }
-                spin_unlock_irqrestore(&state->uart_port->lock, flags);
+                spin_unlock_irqrestore(&uport->lock, flags);
         }
 }
 
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 3c430228d23..c6690a2a27f 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -46,6 +46,8 @@ struct uart_ops {
         unsigned int    (*get_mctrl)(struct uart_port *);
         void            (*stop_tx)(struct uart_port *);
         void            (*start_tx)(struct uart_port *);
+        void            (*throttle)(struct uart_port *);
+        void            (*unthrottle)(struct uart_port *);
         void            (*send_xchar)(struct uart_port *, char ch);
         void            (*stop_rx)(struct uart_port *);
         void            (*enable_ms)(struct uart_port *);
@@ -163,6 +165,10 @@ struct uart_port {
 #define UPF_BUGGY_UART          ((__force upf_t) (1 << 14))
 #define UPF_NO_TXEN_TEST        ((__force upf_t) (1 << 15))
 #define UPF_MAGIC_MULTIPLIER    ((__force upf_t) (1 << 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 s/w flow control */
+#define UPF_SOFT_FLOW           ((__force upf_t) (1 << 22))
 #define UPF_CONS_FLOW           ((__force upf_t) (1 << 23))
 #define UPF_SHARE_IRQ           ((__force upf_t) (1 << 24))
 #define UPF_EXAR_EFR            ((__force upf_t) (1 << 25))