2. Interface Operation
36
Tsi308 User Manual
80D4000_MA001_02
Tundra Semiconductor Corporation
www.tundra.com
2.2.2.1
Memory Mapped Space
The HyperTransport specification places Memory Mapped Space in the address range of
0000_0000_0000_0000h to 0000_00FC_FFFF_FFFFh. The Tsi308 accepts two ranges within
this space, as enabled by MemSpaceEn in the Command (Cmd) CSR, consisting of the
following:
•
Memory Space, defined by the MemBase and MemLimit CSRs.
•
Prefetchable Memory Space, defined by the PrefMemBaseUpper/PrefMemBase and
PrefMemLimitUpper/PrefMemLimit CSRs.
Setting the VgaEn bit in the Bridge Control CSR creates an additional window of
00_000A_0000h to 00_000B_FFFFh, which is also accepted. The Tsi308 never does
prefetching to PCI, so the prefetchable/nonprefetchable attribute of these ranges does not matter.
RdSized requests to these ranges result in MemRd requests on PCI-X bus. WrSized requests to
these ranges result in MemWr requests on the PCI-X bus. If above 4GB, addresses are passed
straight through as a Dual Address Cycle (DAC).
2.2.2.2
I/O Space
The HyperTransport specification places PCI-X I/O space in the address range of
0000_00FD_FC00_0000h to 0000_00FD_FDFF_FFFFh. The Tsi308 strips the top 39 bits off of
the addresses in this range.
•
If enabled by I/OspaceEn in the Cmd CSR, the Tsi308 accepts requests that fall in the range
defined by the I/O Base and I/O Range Base Upper, and I/O Limit and I/O Range Limit
Upper CSRs.
•
If set, the IsaEn bit in Bridge Control CSR creates a series of holes (the top 768 bytes of
each 1 KB block in the low 64 KB) in this space that the Tsi308 does not accept.
•
Setting the VgaEn bit in the Bridge Control CSR creates an additional set of windows (all
addresses in the low 64 KB where the bottom 10 bits are in the ranges 3B0h – 3BBh or
3C0h – 3DFh), which the Tsi308 accepts. Accepted RdSized requests result in IoRd
requests on PCI-X bus, and WrSized requests result in IoWr requests, with the bottom 25
bits of the HyperTransport address passed through. Bits 31:26 are 0.
2.2.2.3
Configuration Space
The HyperTransport specification places PCI-X configuration space in the address range of
0000_00FD_FE00_0000h to 0000_00FD_FFFF_FFFFh. Address bit 24 identifies requests as
Type 0 or Type 1 configuration requests.
•
Type 0 requests are accepted and routed to the Tsi308 internal configuration registers if
their device number (bits 15:11) matches the value of BaseUnitID in the HyperTransport
Command CSR.
Summary of Contents for TSI308
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