Where's a good location in the source tree layout for Mali code?

I plan on moving gralloc for Mali into it's own repo an wondering whereabouts in the source tree it should be placed by the manifest? Possibilities are

/hardware/arm/mali/ /external/mali/ /mali/

Within whatever directory is chosen I plan on having source for all the versions of mali so, e.g.

/hardware/arm/mali/r5p0-06rel0/gralloc /hardware/arm/mali/r5p1-00rel0/gralloc /hardware/arm/mali/r5p1-06rel1/gralloc

With the aim being that the correct one gets chosen to match whatever driver version is in the kernel. I also plan similar for vendor tarball contents, so hopefully we get builds where the three pieces are guaranteed to have matching version (kernel module/gralloc/binary blob)