XIO2001: Does XIO2001 support DMA(Direct Memory Access) feature

On the ISA bus, DMA required hardware support.

But on the PCI and PCI Express buses, all transfers behave the same; on the protocol level, there is no difference between 'normal' accesses and DMA.

A device is said to support DMA if it can originate memory accesses by itself. But a bridge never originates memory accesses; it simply passes through transfers from other devices. The datasheet does not mention DMA because the concept is meaningless for a bridge; any PCI(e) bridge implicitly is able to work together with DMA devices.