Example of how to get all mouse gene coordinates using biomaRt:

library(biomaRt)

mouse <- useMart("ensembl", dataset="mmusculus_gene_ensembl")

# check out what's available
ma <- listAttributes(mouse)

loci <- getBM(attribute=c("ensembl_gene_id", "chromosome_name", "start_position", "end_position", "strand"), mart=mouse)