Commit b3b708fa authored by Guennadi Liakhovetski's avatar Guennadi Liakhovetski Committed by Linus Torvalds
Browse files

wake up from a serial port 



Enable wakeup from serial ports, make it run-time configurable over sysfs,
e.g.,

echo enabled > /sys/devices/platform/serial8250.0/tty/ttyS0/power/wakeup

Requires

# CONFIG_SYSFS_DEPRECATED is not set

Following suggestions from Alan and Russell moved the may_wake_up checks
to serial_core.c. This time actually tested - it does even work. Could
someone, please, verify, that put_device after device_find_child is
correct?

Also would be nice to test with a Natsemi UART, that can wake up the system,
if such systems exist.

For this you just have to apply the patch below, issue the above "echo"
command to one of your Natsemi port, suspend and resume your system, and
verify that your Natsemi port still works.  If you are actually capable of
waking up the system from that port, would be nice to test that as well.

Signed-off-by: default avatarGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent aa5346a2

drivers/serial/serial_core.c

+39 −1
Original line number Diff line number Diff line
@@ -1938,9 +1938,24 @@ static void uart_change_pm(struct uart_state *state, int pm_state) 
	}

}



struct uart_match {

	struct uart_port *port;

	struct uart_driver *driver;

};



static int serial_match_port(struct device *dev, void *data)

{

	struct uart_match *match = data;

	dev_t devt = MKDEV(match->driver->major, match->driver->minor) + match->port->line;



	return dev->devt == devt; /* Actually, only one tty per port */

}



int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)

{

	struct uart_state *state = drv->state + port->line;

	struct device *tty_dev;

	struct uart_match match = {port, drv};



	mutex_lock(&state->mutex);
@@ -1951,6 +1966,15 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port) 
	}

#endif



	tty_dev = device_find_child(port->dev, &match, serial_match_port);

	if (device_may_wakeup(tty_dev)) {

		enable_irq_wake(port->irq);

		put_device(tty_dev);

		mutex_unlock(&state->mutex);

		return 0;

	}

	port->suspended = 1;



	if (state->info && state->info->flags & UIF_INITIALIZED) {

		const struct uart_ops *ops = port->ops;
@@ -1999,6 +2023,13 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port) 
	}

#endif



	if (!port->suspended) {

		disable_irq_wake(port->irq);

		mutex_unlock(&state->mutex);

		return 0;

	}

	port->suspended = 0;



	uart_change_pm(state, 0);



	/*
@@ -2278,6 +2309,7 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port) 
{

	struct uart_state *state;

	int ret = 0;

	struct device *tty_dev;



	BUG_ON(in_interrupt());
@@ -2314,7 +2346,13 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *port) 
	 * Register the port whether it's detected or not.  This allows

	 * setserial to be used to alter this ports parameters.

	 */

	tty_register_device(drv->tty_driver, port->line, port->dev);

	tty_dev = tty_register_device(drv->tty_driver, port->line, port->dev);

	if (likely(!IS_ERR(tty_dev))) {

		device_can_wakeup(tty_dev) = 1;

		device_set_wakeup_enable(tty_dev, 0);

	} else

		printk(KERN_ERR "Cannot register tty device on line %d\n",

		       port->line);



	/*

	 * Ensure UPF_DEAD is not set.

include/linux/serial_core.h

+2 −1
Original line number Diff line number Diff line
@@ -291,7 +291,8 @@ struct uart_port { 
	resource_size_t		mapbase;		/* for ioremap */

	struct device		*dev;			/* parent device */

	unsigned char		hub6;			/* this should be in the 8250 driver */

	unsigned char		unused[3];

	unsigned char		suspended;

	unsigned char		unused[2];

	void			*private_data;		/* generic platform data pointer */

};

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