TTY/Serial fixes for 3.16-rc5

Here are some small serial fixes that resolve some reported problems
 that started in 3.15 with some serial drivers.  And there's a new dt
 binding for a serial driver, which was all that was needed for the
 renesas serial driver.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-3.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty

Pull tty/serial fixes from Greg KH:
 "Here are some small serial fixes that resolve some reported problems
  that started in 3.15 with some serial drivers.

  And there's a new dt binding for a serial driver, which was all that
  was needed for the renesas serial driver"

* tag 'tty-3.16-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: sh-sci: Add device tree support for r8a7{778,740,3a4} and sh73a0
  serial: imx: Fix build breakage
  serial: arc_uart: Use uart_circ_empty() for open-coded comparison
  serial: Test for no tx data on tx restart

Documentation/devicetree/bindings/serial/renesas,sci-serial.txt

@@ -4,6 +4,13 @@ Required properties:
 
   - compatible: Must contain one of the following:
 
+    - "renesas,scifa-sh73a0" for SH73A0 (SH-Mobile AG5) SCIFA compatible UART.
+    - "renesas,scifb-sh73a0" for SH73A0 (SH-Mobile AG5) SCIFB compatible UART.
+    - "renesas,scifa-r8a73a4" for R8A73A4 (R-Mobile APE6) SCIFA compatible UART.
+    - "renesas,scifb-r8a73a4" for R8A73A4 (R-Mobile APE6) SCIFB compatible UART.
+    - "renesas,scifa-r8a7740" for R8A7740 (R-Mobile A1) SCIFA compatible UART.
+    - "renesas,scifb-r8a7740" for R8A7740 (R-Mobile A1) SCIFB compatible UART.
+    - "renesas,scif-r8a7778" for R8A7778 (R-Car M1) SCIF compatible UART.
     - "renesas,scif-r8a7779" for R8A7779 (R-Car H1) SCIF compatible UART.
     - "renesas,scif-r8a7790" for R8A7790 (R-Car H2) SCIF compatible UART.
     - "renesas,scifa-r8a7790" for R8A7790 (R-Car H2) SCIFA compatible UART.

drivers/tty/serial/arc_uart.c

@@ -177,7 +177,7 @@ static void arc_serial_tx_chars(struct arc_uart_port *uart)
 		uart->port.icount.tx++;
 		uart->port.x_char = 0;
 		sent = 1;
-	} else if (xmit->tail != xmit->head) {	/* TODO: uart_circ_empty */
+	} else if (!uart_circ_empty(xmit)) {
 		ch = xmit->buf[xmit->tail];
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
 		uart->port.icount.tx++;

drivers/tty/serial/imx.c

@@ -567,6 +567,9 @@ static void imx_start_tx(struct uart_port *port)
 	struct imx_port *sport = (struct imx_port *)port;
 	unsigned long temp;
 
+	if (uart_circ_empty(&port->state->xmit))
+		return;
+
 	if (USE_IRDA(sport)) {
 		/* half duplex in IrDA mode; have to disable receive mode */
 		temp = readl(sport->port.membase + UCR4);

drivers/tty/serial/ip22zilog.c

@@ -603,6 +603,8 @@ static void ip22zilog_start_tx(struct uart_port *port)
 	} else {
 		struct circ_buf *xmit = &port->state->xmit;
 
+		if (uart_circ_empty(xmit))
+			return;
 		writeb(xmit->buf[xmit->tail], &channel->data);
 		ZSDELAY();
 		ZS_WSYNC(channel);

drivers/tty/serial/m32r_sio.c

@@ -266,9 +266,11 @@ static void m32r_sio_start_tx(struct uart_port *port)
 	if (!(up->ier & UART_IER_THRI)) {
 		up->ier |= UART_IER_THRI;
 		serial_out(up, UART_IER, up->ier);
-		serial_out(up, UART_TX, xmit->buf[xmit->tail]);
-		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
-		up->port.icount.tx++;
+		if (!uart_circ_empty(xmit)) {
+			serial_out(up, UART_TX, xmit->buf[xmit->tail]);
+			xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+			up->port.icount.tx++;
+		}
 	}
 	while((serial_in(up, UART_LSR) & UART_EMPTY) != UART_EMPTY);
 #else

drivers/tty/serial/pmac_zilog.c

@@ -653,6 +653,8 @@ static void pmz_start_tx(struct uart_port *port)
 	} else {
 		struct circ_buf *xmit = &port->state->xmit;
 
+		if (uart_circ_empty(xmit))
+			goto out;
 		write_zsdata(uap, xmit->buf[xmit->tail]);
 		zssync(uap);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
@@ -661,6 +663,7 @@ static void pmz_start_tx(struct uart_port *port)
 		if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 			uart_write_wakeup(&uap->port);
 	}
+ out:
 	pmz_debug("pmz: start_tx() done.\n");
 }
 

drivers/tty/serial/sunsab.c

@@ -427,6 +427,9 @@ static void sunsab_start_tx(struct uart_port *port)
 	struct circ_buf *xmit = &up->port.state->xmit;
 	int i;
 
+	if (uart_circ_empty(xmit))
+		return;
+
 	up->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS|SAB82532_IMR1_XPR);
 	writeb(up->interrupt_mask1, &up->regs->w.imr1);
 	

drivers/tty/serial/sunzilog.c

@@ -703,6 +703,8 @@ static void sunzilog_start_tx(struct uart_port *port)
 	} else {
 		struct circ_buf *xmit = &port->state->xmit;
 
+		if (uart_circ_empty(xmit))
+			return;
 		writeb(xmit->buf[xmit->tail], &channel->data);
 		ZSDELAY();
 		ZS_WSYNC(channel);