questions regarding PCIe

Hi. I need to write two PCIe drivers. One at the host PC and one on the device, which also runs Linux. Basically, the Host needs to map the device memory and initialize DMA access on that. On the Host side, I figured that I need to write an endpoint device, and follow the instructions described in Documentation/PCI/pci.txt. On the device side, I'm quite confused. What kind of driver is it ? Is there a good reference driver in the tree I can look at ? Thanks, Ramon