1 files changed, 29 insertions, 1 deletions

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index ebea4a9d8..c65f9194a 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -694,6 +694,18 @@ static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 		case SC16IS7XX_IIR_RTOI_SRC:
 		case SC16IS7XX_IIR_XOFFI_SRC:
 			rxlen = sc16is7xx_port_read(port, SC16IS7XX_RXLVL_REG);
+
+			/*
+			 * There is a silicon bug that makes the chip report a
+			 * time-out interrupt but no data in the FIFO. This is
+			 * described in errata section 18.1.4.
+			 *
+			 * When this happens, read one byte from the FIFO to
+			 * clear the interrupt.
+			 */
+			if (iir == SC16IS7XX_IIR_RTOI_SRC && !rxlen)
+				rxlen = 1;
+
 			if (rxlen)
 				sc16is7xx_handle_rx(port, rxlen, iir);
 			break;
@@ -1166,9 +1178,18 @@ static int sc16is7xx_gpio_direction_output(struct gpio_chip *chip,
 		state |= BIT(offset);
 	else
 		state &= ~BIT(offset);
-	sc16is7xx_port_write(port, SC16IS7XX_IOSTATE_REG, state);
+
+	/*
+	 * If we write IOSTATE first, and then IODIR, the output value is not
+	 * transferred to the corresponding I/O pin.
+	 * The datasheet states that each register bit will be transferred to
+	 * the corresponding I/O pin programmed as output when writing to
+	 * IOSTATE. Therefore, configure direction first with IODIR, and then
+	 * set value after with IOSTATE.
+	 */
 	sc16is7xx_port_update(port, SC16IS7XX_IODIR_REG, BIT(offset),
 			      BIT(offset));
+	sc16is7xx_port_write(port, SC16IS7XX_IOSTATE_REG, state);
 
 	return 0;
 }
@@ -1255,6 +1276,13 @@ static int sc16is7xx_probe(struct device *dev,
 		s->p[i].port.type	= PORT_SC16IS7XX;
 		s->p[i].port.fifosize	= SC16IS7XX_FIFO_SIZE;
 		s->p[i].port.flags	= UPF_FIXED_TYPE | UPF_LOW_LATENCY;
+		s->p[i].port.iobase	= i;
+		/*
+		 * Use all ones as membase to make sure uart_configure_port() in
+		 * serial_core.c does not abort for SPI/I2C devices where the
+		 * membase address is not applicable.
+		 */
+		s->p[i].port.membase	= (void __iomem *)~0;
 		s->p[i].port.iotype	= UPIO_PORT;
 		s->p[i].port.uartclk	= freq;
 		s->p[i].port.rs485_config = sc16is7xx_config_rs485;