linux-kernel - [PATCH tty-next v3 3/6] serial: 8250: Split out rx stop/start code into helpers

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Message-Id: <20241025105728.602310-4-john.ogness@linutronix.de>
Date: Fri, 25 Oct 2024 13:03:25 +0206
From: John Ogness <john.ogness@...utronix.de>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Jiri Slaby <jirislaby@...nel.org>,
	Petr Mladek <pmladek@...e.com>,
	Sergey Senozhatsky <senozhatsky@...omium.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Esben Haabendal <esben@...nix.com>,
	linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Rengarajan S <rengarajan.s@...rochip.com>,
	Peter Collingbourne <pcc@...gle.com>,
	Serge Semin <fancer.lancer@...il.com>,
	Lino Sanfilippo <l.sanfilippo@...bus.com>
Subject: [PATCH tty-next v3 3/6] serial: 8250: Split out rx stop/start code into helpers

The rx stop/start callbacks also disable/enable interrupts. This
is not acceptable for the console write callback since it must
manage all interrupt disabling/enabling.

Move the interrupt disabling/enabling/masking into helper
functions so that the console write callback can make use of
the appropriate parts in a follow-up commit.

This is essentially refactoring and should cause no functional
change.

Signed-off-by: John Ogness <john.ogness@...utronix.de>
---
 drivers/tty/serial/8250/8250_port.c | 37 ++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 8f7c9968ad41..09ac521d232a 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1360,18 +1360,37 @@ static void autoconfig_irq(struct uart_8250_port *up)
 	port->irq = (irq > 0) ? irq : 0;
 }
 
-static void serial8250_stop_rx(struct uart_port *port)
+static void __serial8250_stop_rx_mask_dr(struct uart_port *port)
 {
-	struct uart_8250_port *up = up_to_u8250p(port);
+	port->read_status_mask &= ~UART_LSR_DR;
+}
 
+static void __serial8250_stop_rx_int(struct uart_8250_port *p)
+{
 	/* Port locked to synchronize UART_IER access against the console. */
-	lockdep_assert_held_once(&port->lock);
+	lockdep_assert_held_once(&p->port.lock);
+
+	p->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
+	serial_port_out(&p->port, UART_IER, p->ier);
+}
+
+static void __serial8250_start_rx_int(struct uart_8250_port *p)
+{
+	/* Port locked to synchronize UART_IER access against the console. */
+	lockdep_assert_held_once(&p->port.lock);
+
+	p->ier |= UART_IER_RLSI | UART_IER_RDI;
+	serial_port_out(&p->port, UART_IER, p->ier);
+}
+
+static void serial8250_stop_rx(struct uart_port *port)
+{
+	struct uart_8250_port *up = up_to_u8250p(port);
 
 	serial8250_rpm_get(up);
 
-	up->ier &= ~(UART_IER_RLSI | UART_IER_RDI);
-	up->port.read_status_mask &= ~UART_LSR_DR;
-	serial_port_out(port, UART_IER, up->ier);
+	__serial8250_stop_rx_mask_dr(port);
+	__serial8250_stop_rx_int(up);
 
 	serial8250_rpm_put(up);
 }
@@ -1386,9 +1405,6 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p)
 {
 	unsigned char mcr = serial8250_in_MCR(p);
 
-	/* Port locked to synchronize UART_IER access against the console. */
-	lockdep_assert_held_once(&p->port.lock);
-
 	if (p->port.rs485.flags & SER_RS485_RTS_AFTER_SEND)
 		mcr |= UART_MCR_RTS;
 	else
@@ -1403,8 +1419,7 @@ void serial8250_em485_stop_tx(struct uart_8250_port *p)
 	if (!(p->port.rs485.flags & SER_RS485_RX_DURING_TX)) {
 		serial8250_clear_and_reinit_fifos(p);
 
-		p->ier |= UART_IER_RLSI | UART_IER_RDI;
-		serial_port_out(&p->port, UART_IER, p->ier);
+		__serial8250_start_rx_int(p);
 	}
 }
 EXPORT_SYMBOL_GPL(serial8250_em485_stop_tx);
-- 
2.39.5