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4. Addressing
50
Tsi384 User Manual
May 5, 2014
Integrated Device Technology
www.idt.com
A bridge uses the I/O Base and I/O Limit registers to determine whether to forward I/O transactions
across the bridge, as shown in
. The I/O address range defined by these registers is always
aligned to a 4-KB boundary and has a size granularity of 4 KB. A bridge forwards I/O read and I/O
write transactions from its PCIe Interface to its PCI/X Interface if the address is in the range defined by
the I/O base and I/O limit registers (when the base is less than or equal to the limit). Conversely, I/O
transactions on the PCI/X bus in the address range defined by these registers are not forwarded
upstream by the bridge. I/O transactions on the PCI/X bus that are outside the defined address range are
forwarded upstream.
4.5
VGA Addressing
The Tsi384 supports VGA addressing. The VGA_EN bit in the
“PCI Bridge Control and Interrupt
controls the response by the bridge to both VGA frame buffer addresses and to VGA register
addresses. If the VGA Enable bit is set, the bridge decodes and forwards memory accesses to VGA
frame buffer addresses and I/O accesses to VGA registers from the PCIe Interface to the PCI/X
Interface (and block forwarding from PCI/X to PCIe of these same accesses).
The VGA_16BIT_EN bit in the
“PCI Bridge Control and Interrupt Register”
selects between 10-bit
and 16-bit VGA I/O address decoding, and is applicable when the VGA Enable bit is 1.
VGA memory addresses are 0x0A_0000 through 0x0B_FFFF
VGA I/O Addresses (Address bits 15:10 are not decoded when the VGA 16-Bit Decode bit is 0b) are:
•
Address bits 9:0 = 0x3B0 through 0x3BB and 0x3C0 through 0x3DF (VGA 16-Bit Decode bit is
0b)
•
Address bits 15:0 = 0x03B0 through 0x03BB and 0x03C0 through 0x03DF (VGA 16-bit Decode
bit is 1b)
The VGA Palette Snoop Enable bit is implemented as read-only with a value of zero.
4.6
ISA Addressing
The Tsi384 supports ISA addressing through ISA Enable bit in the
“PCI Bridge Control and Interrupt
. The ISA Enable affects only I/O addresses that are in the bridge’s I/O range (as defined by
the I/O Base, I/O Base Upper 16 Bits, I/O Limit, and I/O Limit Upper 16 Bits) and in the first 64 KB of
PCI/X I/O Space (0000 0000h to 0000 FFFFh). If this bit is set and the I/O address meets the stated
constraints, the Tsi384 blocks the forwarding of I/O transactions downstream if the I/O address is in the
top 768 bytes of each naturally aligned 1-KB block. If the ISA Enable bit is clear, the Tsi384 forwards
downstream all I/O addresses in the address range defined by the I/O Base and I/O Limit registers.
If the ISA Enable bit is set, I/O transactions on the PCI/X bus in the top 768 bytes of any 1-KB address
block within the first 64 KB of PCI/X I/O space is forwarded upstream, even if the address is between
the I/O base and I/O limit addresses.
illustrates this mapping for a 4-KB range.
The ISA Enable bit only affects the I/O address decoding behavior of the bridge. It does not affect the
bridge's prefetching, posting, ordering, or error handling behavior.
Содержание TSI384
Страница 1: ... IDT Tsi384 PCIe to PCI Bridge User Manual May 5 2014 ...
Страница 10: ...Contents 10 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 36: ...2 Signal Descriptions 36 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 56: ...4 Addressing 56 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 62: ...5 Configuration Transactions 62 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 74: ...6 Bridging 74 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 78: ...7 PCI X Arbitration 78 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 128: ...11 Power Management 128 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 136: ...12 Serial EEPROM 136 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 142: ...13 JTAG 142 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 268: ...16 Packaging 268 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 276: ...276 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...
Страница 280: ...Index 280 Tsi384 User Manual May 5 2014 Integrated Device Technology www idt com ...