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: Guennadi 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 09d17b06bf02..4db77249281c 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -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 */
 };