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@kernel.org>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20250611100319.186924-18-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 6851c197b31de28188c5b97d90df833e76269b94..a73f4db22feb2f6f6e068bb83eab8ceb4abf3ba8 100644 (file)
--- 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;