linux-kernel - [PATCH 5/7] serial: 8250: Implement poll_get

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Date:   Mon, 22 Jun 2020 19:56:22 +0530
From:   Sumit Garg <sumit.garg@...aro.org>
To:     kgdb-bugreport@...ts.sourceforge.net, linux-serial@...r.kernel.org
Cc:     gregkh@...uxfoundation.org, daniel.thompson@...aro.org,
        jason.wessel@...driver.com, dianders@...omium.org, jslaby@...e.com,
        linux@...linux.org.uk, linux-kernel@...r.kernel.org,
        Sumit Garg <sumit.garg@...aro.org>
Subject: [PATCH 5/7] serial: 8250: Implement poll_get_irq() interface

From: Daniel Thompson <daniel.thompson@...aro.org>

Support kgdb NMI console feature via implementing poll_get_irq()
interface. This will allow usage of RX interrupts to support kgdb entry
while serial device is operating in polling mode.

Signed-off-by: Daniel Thompson <daniel.thompson@...aro.org>
Signed-off-by: Sumit Garg <sumit.garg@...aro.org>
---
 drivers/tty/serial/8250/8250_port.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index f77bf82..1473b1a 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -2138,6 +2138,21 @@ static void serial8250_put_poll_char(struct uart_port *port,
 	serial8250_rpm_put(up);
 }
 
+static int serial8250_get_poll_irq(struct uart_port *port)
+{
+	unsigned int ier;
+	struct uart_8250_port *up = up_to_u8250p(port);
+
+	serial8250_rpm_get(up);
+
+	ier = serial_port_in(port, UART_IER);
+	ier |= UART_IER_RLSI | UART_IER_RDI;
+	serial_port_out(port, UART_IER, ier);
+
+	serial8250_rpm_put(up);
+	return port->irq;
+}
+
 #endif /* CONFIG_CONSOLE_POLL */
 
 int serial8250_do_startup(struct uart_port *port)
@@ -3141,6 +3156,7 @@ static const struct uart_ops serial8250_pops = {
 #ifdef CONFIG_CONSOLE_POLL
 	.poll_get_char = serial8250_get_poll_char,
 	.poll_put_char = serial8250_put_poll_char,
+	.poll_get_irq  = serial8250_get_poll_irq,
 #endif
 };
 
-- 
2.7.4