Hello!

This is about the I2C-Bus Real Time Clock chip driver 
linux/drivers/i2c/chips/rtc8564.c in current 2.6.15-rc5.

According to the datasheets for the RTC8564 and the PCF8563
http://www.e-lab.de/downloads/DOCs/RTC8564.pdf
http://www.semiconductors.philips.com/acrobat_download/datasheets/PCF8563-04.pdf
the rtc memory content is the same and compatible.

While merging/porting a pcf8563.c driver which is used on
my embedded ppc board to the rtc8564.c, I had to realize that the
century bit isn't used in the current driver. Instead, the
alarm-minute-register is misused to get the century correct.
So, I suggest the following patch to use the century bit as intended
and add some notes about the pcf8653 compatibility. I've left the
century bit polarity "as is" from the pcf8563 driver to avoid any
existing changes, but that behaviour could be changed according
to the datasheet.
rtc8564_do_command() will be used by my platform initialization code.
(some more patches follow)

Thanks!

Signed-off-by: Clemens Koller <clemens.koller@anagramm.de>
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