serial: turn serial console suspend a boot rather than compile time option

Currently, there's a CONFIG_DISABLE_CONSOLE_SUSPEND that allows one to stop
the serial console from being suspended when the rest of the machine goes
to sleep.  This is incredibly useful for debugging power management-related
things; however, having it as a compile-time option has proved to be
incredibly inconvenient for us (OLPC).  There are plenty of times that we
want serial console to not suspend, but for the most part we'd like serial
console to be suspended.

This drops CONFIG_DISABLE_CONSOLE_SUSPEND, and replaces it with a kernel
boot parameter (no_console_suspend).  By default, the serial console will
be suspended along with the rest of the system; by passing
'no_console_suspend' to the kernel during boot, serial console will remain
alive during suspend.

For now, this is pretty serial console specific; further fixes could be
applied to make this work for things like netconsole.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Acked-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@suspend2.net>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 6 deletions

diff --git a/drivers/serial/serial_core.c b/drivers/serial/serial_core.c
index 68aa4da01865..103189095c80 100644
--- a/drivers/serial/serial_core.c
+++ b/drivers/serial/serial_core.c
@@ -1959,12 +1959,11 @@ int uart_suspend_port(struct uart_driver *drv, struct uart_port *port)
 
         mutex_lock(&state->mutex);
 
-#ifdef CONFIG_DISABLE_CONSOLE_SUSPEND
-        if (uart_console(port)) {
+        if (!console_suspend_enabled && uart_console(port)) {
+                /* we're going to avoid suspending serial console */
                 mutex_unlock(&state->mutex);
                 return 0;
         }
-#endif
 
         tty_dev = device_find_child(port->dev, &match, serial_match_port);
         if (device_may_wakeup(tty_dev)) {
@@ -2016,12 +2015,11 @@ int uart_resume_port(struct uart_driver *drv, struct uart_port *port)
 
         mutex_lock(&state->mutex);
 
-#ifdef CONFIG_DISABLE_CONSOLE_SUSPEND
-        if (uart_console(port)) {
+        if (!console_suspend_enabled && uart_console(port)) {
+                /* no need to resume serial console, it wasn't suspended */
                 mutex_unlock(&state->mutex);
                 return 0;
         }
-#endif
 
         if (!port->suspended) {
                 disable_irq_wake(port->irq);