[Balloon] unified rtc driver for 2.4.25-vrs2-tcl1

I have enhanced the sa1100-rtc driver with optional support from the balloon's pfc8583 rtc in kernel 2.4.25-vrs2-tcl1.

In the kernel configuration, if the balloon_rtc option is chosen along with the i2c bus and pfc8583 then if the rtc chip is detected it is used to set the sa1100-rtc otherwise the driver runs the sa1100 internal oscillatior starting at 1/1/1970. Asserting the date in the sa1100-rtc sets the pcf8583 time as well when detected.

This is a simpler arrangement that selecting support for one or other devices so that boards that both have the chip and do not have the chip can use the same kernel binary to implement /dev/rtc.

The kernel in the development/kernel/2.4.25 directory has this built in so no extra modules are needed. The boot console messages indicate whether the pcf8583 RTC is detected.

I will do the same port for 2.6.8.1 on Thursday.

RTC support for Mainstone in 2.6.9-rc2-tcl1 already works but the source is not yet released.

Nick Bane