linux-kernel - [PATCH v2 08/23] tty: serial: fls_lpuart: Split shared TX IRQ handler into two

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Date:   Wed, 31 Jul 2019 10:30:30 -0700
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     linux-serial@...r.kernel.org
Cc:     Andrey Smirnov <andrew.smirnov@...il.com>,
        Stefan Agner <stefan@...er.ch>,
        Chris Healy <cphealy@...il.com>,
        Cory Tusar <cory.tusar@....aero>,
        Lucas Stach <l.stach@...gutronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, linux-imx@....com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 08/23] tty: serial: fls_lpuart: Split shared TX IRQ handler into two

While sharing code for Tx interrupt handler between 8 and 32 bit
variant of the peripheral saves a bit of code duplication it also adds
quite a number of lpuart_is_32() checks which makes it harder to
understand. Move shared bits back into corresponding
lpuart*_transmit_buffer functions, split lpuart_txint into
lpuart_txint and lpuart32_txint so we can drop all extra
lpuart_is_32() check and make the code flow more linear.

Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
Cc: Stefan Agner <stefan@...er.ch>
Cc: Chris Healy <cphealy@...il.com>
Cc: Cory Tusar <cory.tusar@....aero>
Cc: Lucas Stach <l.stach@...gutronix.de>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jslaby@...e.com>
Cc: linux-imx@....com
Cc: linux-serial@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
---
 drivers/tty/serial/fsl_lpuart.c | 61 +++++++++++++++++++--------------
 1 file changed, 35 insertions(+), 26 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index 8657addbfd1c..ed6d3f836c93 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -663,6 +663,18 @@ static inline void lpuart_transmit_buffer(struct lpuart_port *sport)
 {
 	struct circ_buf *xmit = &sport->port.state->xmit;
 
+	if (sport->port.x_char) {
+		writeb(sport->port.x_char, sport->port.membase + UARTDR);
+		sport->port.icount.tx++;
+		sport->port.x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+		lpuart_stop_tx(&sport->port);
+		return;
+	}
+
 	while (!uart_circ_empty(xmit) &&
 		(readb(sport->port.membase + UARTTCFIFO) < sport->txfifo_size)) {
 		writeb(xmit->buf[xmit->tail], sport->port.membase + UARTDR);
@@ -682,6 +694,18 @@ static inline void lpuart32_transmit_buffer(struct lpuart_port *sport)
 	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long txcnt;
 
+	if (sport->port.x_char) {
+		lpuart32_write(&sport->port, sport->port.x_char, UARTDATA);
+		sport->port.icount.tx++;
+		sport->port.x_char = 0;
+		return;
+	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
+		lpuart32_stop_tx(&sport->port);
+		return;
+	}
+
 	txcnt = lpuart32_read(&sport->port, UARTWATER);
 	txcnt = txcnt >> UARTWATER_TXCNT_OFF;
 	txcnt &= UARTWATER_COUNT_MASK;
@@ -773,34 +797,10 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port)
 
 static void lpuart_txint(struct lpuart_port *sport)
 {
-	struct circ_buf *xmit = &sport->port.state->xmit;
 	unsigned long flags;
 
 	spin_lock_irqsave(&sport->port.lock, flags);
-	if (sport->port.x_char) {
-		if (lpuart_is_32(sport))
-			lpuart32_write(&sport->port, sport->port.x_char, UARTDATA);
-		else
-			writeb(sport->port.x_char, sport->port.membase + UARTDR);
-		sport->port.icount.tx++;
-		sport->port.x_char = 0;
-		goto out;
-	}
-
-	if (uart_circ_empty(xmit) || uart_tx_stopped(&sport->port)) {
-		if (lpuart_is_32(sport))
-			lpuart32_stop_tx(&sport->port);
-		else
-			lpuart_stop_tx(&sport->port);
-		goto out;
-	}
-
-	if (lpuart_is_32(sport))
-		lpuart32_transmit_buffer(sport);
-	else
-		lpuart_transmit_buffer(sport);
-
-out:
+	lpuart_transmit_buffer(sport);
 	spin_unlock_irqrestore(&sport->port.lock, flags);
 }
 
@@ -876,6 +876,15 @@ static void lpuart_rxint(struct lpuart_port *sport)
 	tty_flip_buffer_push(port);
 }
 
+static void lpuart32_txint(struct lpuart_port *sport)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&sport->port.lock, flags);
+	lpuart32_transmit_buffer(sport);
+	spin_unlock_irqrestore(&sport->port.lock, flags);
+}
+
 static void lpuart32_rxint(struct lpuart_port *sport)
 {
 	unsigned int flg, ignored = 0;
@@ -967,7 +976,7 @@ static irqreturn_t lpuart32_int(int irq, void *dev_id)
 		lpuart32_rxint(sport);
 
 	if ((sts & UARTSTAT_TDRE) && !sport->lpuart_dma_tx_use)
-		lpuart_txint(sport);
+		lpuart32_txint(sport);
 
 	lpuart32_write(&sport->port, sts, UARTSTAT);
 	return IRQ_HANDLED;
-- 
2.21.0