Bitbanging SPI driver


I want to attach a DS3234 RTC (breakout board from Sparkfun) to my
The beaglebone is combined withThe following capes:
LCD7, RS232, Audio, (breakoutboard)

Due to this setup the SPI pins are all occupied for other
uses as far as I can see.

Thats why I want to bitbang a SPI master. Speed is no problem,
since the clock will be accessed once at boot time to set the
systems clock and sometimes when it needs to set/correct the time
by hand.

With the Linux kernel sources there is a GPIO-SPI bitbang driver.

Unfortunately I didnt find any tutorial or howto how to use it.

At the moment I dont want to buy an RTC with I2C bus.

Where can I find the needed informations to successfully use
the DS3234 with my beaglebone?

Thank you very much in advance for any help!

Best regards,