Hi,
I encountered a similar problem with USB, mass storage worked, but the mice haven't been detected...
My Solution: Since mice are (mostly) using lowspeed usb, which is not handled by EHCI, it is necessary to have also OHCI support. EHCI is passing lowspeed devices to the OHCI driver and everything should work.
To do this, it is necessary to change the kernel .config: (make menuconfig)
Device Drivers --->
[*] USB support --->
<*> OHCI HCD support
[*] OHCI support for Samsung S5PV210 SoC Series
Then, after typing "make" u get your new zImage in arch/arm/boot.
(My gcc gave me first an error: "following symbols must have non local/private scope: fifo_mask" and refused building the zImage. Solution: arch/arm/plat-samsung/include/plat/uncompress.h Line 24: change to "unsigned int fifo_mask;" )
Best regards
Daniel