diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index bf0065d1c8e9..9f2fcd1c1916 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -326,6 +326,7 @@ struct sc16is7xx_one {
 	struct kthread_work		reg_work;
 	struct kthread_delayed_work	ms_work;
 	struct sc16is7xx_one_config	config;
+	unsigned char			buf[SC16IS7XX_FIFO_SIZE]; /* Rx buffer. */
 	unsigned int			old_mctrl;
 	u8				old_lcr; /* Value before EFR access. */
 	bool				irda_mode;
@@ -339,7 +340,6 @@ struct sc16is7xx_port {
 	unsigned long			gpio_valid_mask;
 #endif
 	u8				mctrl_mask;
-	unsigned char			buf[SC16IS7XX_FIFO_SIZE];
 	struct kthread_worker		kworker;
 	struct task_struct		*kworker_task;
 	struct sc16is7xx_one		p[];
@@ -611,18 +611,18 @@ static int sc16is7xx_set_baud(struct uart_port *port, int baud)
 static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
 				unsigned int iir)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
+	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 	unsigned int lsr = 0, bytes_read, i;
 	bool read_lsr = (iir == SC16IS7XX_IIR_RLSE_SRC) ? true : false;
 	u8 ch, flag;
 
-	if (unlikely(rxlen >= sizeof(s->buf))) {
+	if (unlikely(rxlen >= sizeof(one->buf))) {
 		dev_warn_ratelimited(port->dev,
 				     "ttySC%i: Possible RX FIFO overrun: %d\n",
 				     port->line, rxlen);
 		port->icount.buf_overrun++;
 		/* Ensure sanity of RX level */
-		rxlen = sizeof(s->buf);
+		rxlen = sizeof(one->buf);
 	}
 
 	while (rxlen) {
@@ -635,10 +635,10 @@ static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
 			lsr = 0;
 
 		if (read_lsr) {
-			s->buf[0] = sc16is7xx_port_read(port, SC16IS7XX_RHR_REG);
+			one->buf[0] = sc16is7xx_port_read(port, SC16IS7XX_RHR_REG);
 			bytes_read = 1;
 		} else {
-			sc16is7xx_fifo_read(port, s->buf, rxlen);
+			sc16is7xx_fifo_read(port, one->buf, rxlen);
 			bytes_read = rxlen;
 		}
 
@@ -671,7 +671,7 @@ static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
 		}
 
 		for (i = 0; i < bytes_read; ++i) {
-			ch = s->buf[i];
+			ch = one->buf[i];
 			if (uart_handle_sysrq_char(port, ch))
 				continue;
 
@@ -689,10 +689,10 @@ static void sc16is7xx_handle_rx(struct uart_port *port, unsigned int rxlen,
 
 static void sc16is7xx_handle_tx(struct uart_port *port)
 {
-	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	struct tty_port *tport = &port->state->port;
 	unsigned long flags;
 	unsigned int txlen;
+	unsigned char *tail;
 
 	if (unlikely(port->x_char)) {
 		sc16is7xx_port_write(port, SC16IS7XX_THR_REG, port->x_char);
@@ -717,8 +717,9 @@ static void sc16is7xx_handle_tx(struct uart_port *port)
 		txlen = 0;
 	}
 
-	txlen = uart_fifo_out(port, s->buf, txlen);
-	sc16is7xx_fifo_write(port, s->buf, txlen);
+	txlen = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail, txlen);
+	sc16is7xx_fifo_write(port, tail, txlen);
+	uart_xmit_advance(port, txlen);
 
 	uart_port_lock_irqsave(port, &flags);
 	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)