The SBI interface is an AMD proprietary interface that buffers incoming configuration data from the supervised boot modes (JTAG and SelectMAP). The incoming data is then fetched by the RCU or PPU using one of the platform management controller DMAs for further processing and loading to the configuration interfaces. For SelectMAP, the SBI requires flow control to prevent overflow of the internal buffer using a SMAP_BUSY signal. When the SMAP_BUSY signal is asserted, the external controller must pause sending data by deasserting SMAP_CS_b within 24 SMAP_CLK cycles. The data can be resent once the SMAP_BUSY signal is deasserted.
The DPC, SelectMAP, and JTAG data are adjusted to the 128-bit bus for processing.
Figure 1. SBI Datapath
