I have a friend with new Aspire One AO532h that has an SD card controller made by ENE in Taiwan. It does not seem to have a common linux driver.
I researched it for him and found this link:https://bugs.launchpad.net/linux/+bug/530277
It seems it reports there is a driver from the Moblin project that might work.
You might do lspci and search on the SD card controller chip part number. If it is made by ENE you might be able to scrounge up some source code from one of the sources alluded to in the link above.
ENE seems to think it should keep the technical data about their controllers on a need to know basis, since there is no engineering data on their web site, just marketing descriptions.
I hope you are successful in your driver quest.