linux-kernel - [PATCH 17/33] serial: 8250: extract serial8250_clear

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Message-ID: <20250611100319.186924-18-jirislaby@kernel.org>
Date: Wed, 11 Jun 2025 12:03:03 +0200
From: "Jiri Slaby (SUSE)" <jirislaby@...nel.org>
To: gregkh@...uxfoundation.org
Cc: linux-serial@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	"Jiri Slaby (SUSE)" <jirislaby@...nel.org>
Subject: [PATCH 17/33] serial: 8250: extract serial8250_clear_interrupts()

On three places in 8250_port.c, the interrupts are cleared by reading 4
registers. Extract this to a separate function:
serial8250_clear_interrupts(). And call it from all the places.

Note autoconfig_irq() now uses serial_port_in() instead of serial_in().
But they are the same, in fact (modulo parameter).

Signed-off-by: Jiri Slaby (SUSE) <jirislaby@...nel.org>
---
 drivers/tty/serial/8250/8250_port.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 6851c197b31d..a73f4db22feb 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -705,6 +705,15 @@ static void serial8250_set_sleep(struct uart_8250_port *p, int sleep)
 	serial8250_rpm_put(p);
 }
 
+/* Clear the interrupt registers. */
+static void serial8250_clear_interrupts(struct uart_port *port)
+{
+	serial_port_in(port, UART_LSR);
+	serial_port_in(port, UART_RX);
+	serial_port_in(port, UART_IIR);
+	serial_port_in(port, UART_MSR);
+}
+
 static void serial8250_clear_IER(struct uart_8250_port *up)
 {
 	if (up->capabilities & UART_CAP_UUE)
@@ -1275,10 +1284,7 @@ static void autoconfig_irq(struct uart_8250_port *up)
 	uart_port_lock_irq(port);
 	serial_out(up, UART_IER, UART_IER_ALL_INTR);
 	uart_port_unlock_irq(port);
-	serial_in(up, UART_LSR);
-	serial_in(up, UART_RX);
-	serial_in(up, UART_IIR);
-	serial_in(up, UART_MSR);
+	serial8250_clear_interrupts(port);
 	serial_out(up, UART_TX, 0xFF);
 	udelay(20);
 	irq = probe_irq_off(irqs);
@@ -2322,13 +2328,7 @@ int serial8250_do_startup(struct uart_port *port)
 	 */
 	serial8250_clear_fifos(up);
 
-	/*
-	 * Clear the interrupt registers.
-	 */
-	serial_port_in(port, UART_LSR);
-	serial_port_in(port, UART_RX);
-	serial_port_in(port, UART_IIR);
-	serial_port_in(port, UART_MSR);
+	serial8250_clear_interrupts(port);
 
 	/*
 	 * At this point, there's no way the LSR could still be 0xff;
@@ -2363,10 +2363,7 @@ int serial8250_do_startup(struct uart_port *port)
 	 * saved flags to avoid getting false values from polling
 	 * routines or the previous session.
 	 */
-	serial_port_in(port, UART_LSR);
-	serial_port_in(port, UART_RX);
-	serial_port_in(port, UART_IIR);
-	serial_port_in(port, UART_MSR);
+	serial8250_clear_interrupts(port);
 	up->lsr_saved_flags = 0;
 	up->msr_saved_flags = 0;
 
-- 
2.49.0