[PATCH 2/3] tty: serial_core: add wakeup_irq to support in-band wakeup

[Claire Chang]

Since some uart controllers may be off in S3, we won't be able to use
the normal in-band wakeup.

Take 8250_mtk.c as an example. The driver needs to allocate an edge
sensitive interrupt as the wakeup_irq and use an addtional pinctrl to
reconfigure Rx pin to normal GPIO in sleep state. Once host detects Rx
falling, an interrupt is triggered, and the system leaves sleep state.

Add the wakeup_irq logic in core to simplify and make the code more
generic. Also, we can align with the original wakeup behavior and
power/wakeup node.

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_core.c | 1 +
 drivers/tty/serial/serial_core.c    | 8 +++++---
 include/linux/serial_core.h         | 1 +
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 45d9117cab680..06214e9fdc8ff 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1001,6 +1001,7 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
 		uart->port.membase      = up->port.membase;
 		uart->port.irq          = up->port.irq;
 		uart->port.irqflags     = up->port.irqflags;
+		uart->port.wakeup_irq	= up->port.wakeup_irq;
 		uart->port.uartclk      = up->port.uartclk;
 		uart->port.fifosize     = up->port.fifosize;
 		uart->port.regshift     = up->port.regshift;
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 66a5e2faf57ea..1796a33986613 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2165,12 +2165,13 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *uport)
 	struct tty_port *port = &state->port;
 	struct device *tty_dev;
 	struct uart_match match = {uport, drv};
+	int irq = uport->wakeup_irq > 0 ? uport->wakeup_irq : uport->irq;
 
 	mutex_lock(&port->mutex);
 
 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
 	if (tty_dev && device_may_wakeup(tty_dev)) {
-		enable_irq_wake(uport->irq);
+		enable_irq_wake(irq);
 		put_device(tty_dev);
 		mutex_unlock(&port->mutex);
 		return 0;
@@ -2228,13 +2229,14 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *uport)
 	struct device *tty_dev;
 	struct uart_match match = {uport, drv};
 	struct ktermios termios;
+	int irq = uport->wakeup_irq > 0 ? uport->wakeup_irq : uport->irq;
 
 	mutex_lock(&port->mutex);
 
 	tty_dev = device_find_child(uport->dev, &match, serial_match_port);
 	if (!uport->suspended && device_may_wakeup(tty_dev)) {
-		if (irqd_is_wakeup_set(irq_get_irq_data((uport->irq))))
-			disable_irq_wake(uport->irq);
+		if (irqd_is_wakeup_set(irq_get_irq_data((irq))))
+			disable_irq_wake(irq);
 		put_device(tty_dev);
 		mutex_unlock(&port->mutex);
 		return 0;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 92f5eba860528..5764687b90a36 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -136,6 +136,7 @@ struct uart_port {
 						  struct serial_iso7816 *iso7816);
 	unsigned int		irq;			/* irq number */
 	unsigned long		irqflags;		/* irq flags  */
+	unsigned int		wakeup_irq;		/* wakeup irq number */
 	unsigned int		uartclk;		/* base uart clock */
 	unsigned int		fifosize;		/* tx fifo size */
 	unsigned char		x_char;			/* xon/xoff char */
-- 
2.26.2.526.g744177e7f7-goog