This is based on the crosvm resource allocator from commit 107edb3e.
We only have PIO and MMIO address space to handle, and don't have a GPU
specific path and space.
Also, we support allocating a range at a specified address. This is
mostly useful for PIO, but might be also necessary for MMIO.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
