PadLock is VIA's hardware-based security engine embedded into their recent x86 processors (among them are the VIA Eden, C3, and C7 processors). The VIA PadLock provides a random number generator, advanced cryptography engine, and RSA algorithm computation. The VIA PadLock programming guide appears to cover all areas of this security engine.
The VX800 chipset was VIA's first IGP (Integrated Graphics Processor) with Microsoft DirectX 9.0 support and contains a variety of other features and enhancements. The VIA VX800/VX820 documentation is 494 pages and it provides a register overview for both Northbridge and Southbridge functionality from shadow RAM controls and SATA links to power management. This documentation was last updated last month and still contains VIA's confidential watermarks, even though this documentation is distributed freely with no Non-Disclosure Agreement.
The CX700 documentation is similar to that of the VX800/820, but instead it covers VIA's single-chip system media processor designed for the mobile market. The VIA CX700 uses the UniChrome Pro graphics processor and supports other features such as Serial ATA 2.0, DDR2, etc. This register reference guide is just over 200 pages.
These three documents along with other source-code and binary drivers can be downloaded from the VIA Linux page.