RTC subsystem

Hello,

thanks to all the suggestions I've got, I've
updated my proposal [1] for an RTC subsystem.

I tried to implement locking wherever necessary.
I'm on vacations right now and I don't have all the feedback emails at handy, so I'm sure I've forgot something.

I've left some XXX in the points where I have
doubts.

The dev interface now supports multiple RTCs and
hotplug events are generated whenever an RTC is added/removed.

Those udev lines can be used to create the device nodes

ACTION=="add", SUBSYSTEM=="rtc", ENV{MAJOR}=="[0-9]*", NAME="rtc%m"
ACTION=="add", SUBSYSTEM=="rtc", ENV{MINOR}=="0", SYMLINK+="rtc"

I also added a test device/driver which can be used
to excercize the APIs. This device can also generate interrupts using the sysfs interface (more details in the path).

hwclock seems to work fine, both in polling
and IRQ modes.

 Best regards,

 Alessandro Zummo,
  Tower Technologies - Turin, Italy

  http://www.towertech.it

[1]
	http://lkml.org/lkml/2005/12/20/220