The iMac G5 and latest single-cpu PowerMac G5 have seen the venerable PMU
(Power Management Unit) chip been sent to well deserved retirement.  It has
been replaced by a newcomer, the SMU (System Management Unit ?) which is of
course totally undocumented and has no open source darwin driver...  The
SMU chip is responsible of initializing the chipset & CPU (boot process),
power supply control, real time clock, fan control, provides some i2c
busses, etc...  etc...  etc...

This is a very basic driver based on the Open Firmware methods for
accessing this chip.  It provides synchronous functions only, and does
restart, shutdown, and real time clock access.  There is still no fan
control, at least not until we have figured out how to access the fans via
the SMU.

The initial code was written by J.  Mayer <l_indien@magic.fr>, I mostly
rewrote it to better adhere to our coding style standards ;)

The patch also updates the g5_defconfig to include the SMU support by
default.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>