Seems like there's little information publicly available about the AM1 platform. As you can see here [1] there's plenty of information available for the Bolton FCH which is used in newer APUs, while the Hudson FCH is basically undocumented.
The BKDG for the Kabini platform [2] mentions two registers ("D0F0x98_x26 ORB IOMMU Control 0" and "D0F0x98_x27 ORB IOMMU Control 1") which suggests the platform has an IOMMU.
A reddit thread [3] quotes a customer service response from AMD which confirms the platform has an IOMMU but the ability to use it depends on the mainboard being used:
"Yes the processor AMD AM1 5350 supports PCI Pass through via
AMD-Vi/IOMMU. However, we request you to contact the motherboard
manufacturer and check if the Motherboard and Chipset support IOMMU."
Maybe the best way to see this is to try virtualizing some hardware?
Regards,