Chapter 8: PCI/G-Bus Bridge
TX7901 User’s Manual (Rev. 6.30T – Nov, 2001)
8-13
8.2.9 PCI to G-Bus Address Mapping
The PGB performs PCI to G-Bus address mapping using the mechanism shown in the figure
below.
Figure 8-9 PCI to G-Bus Address Mapping
8.2.10 Bus Error Handling Policies
The PCI core supports PCI bus parity and system error capabilities. These errors are
forwarded to the application side of the core. The PGB performs the actions described below
when errors are detected.
8.2.10.1
Transactions with a PCI Master
PCI parity errors detected by the PGB for transactions with a PCI Master are reported by the
core to the PCI Master using the PERR signal. The PGB completes the transaction without
reporting errors to the G-Bus. If a PCI to G-Bus write cycle encounters a PCI error, the G-
Bus transfer (single or burst) is completed with undefined data. G-Bus errors are not
Target Dest.
Path
Target FSM
Target Address
Path
membase[0]
membase[1]
membase[2]
I/O base[0]
Membase[0]
Membase[1]
I/O base[0]
PCI Map
CORE
/4
/4
L
/36
folding/unfolding
registers/muxes
Bus holding
Decoder
/36
pgbase[0]
pgbase[1]
pgbase[3]
GBUS Map
Main memory:
pgbase[0]
Rom, SRAM, I/O,
pgbase[2]
TX7901 registers:
pgbase[3]
gAddr[35:0]
Addr
'0'
Size = M,N,P,Q
if(PCI.hit[0[)
gbus.addr = pgbase[0][35:M] | gbus.addr[M - 1:0];
if(PCI.hit[1])
gbus.addr = pgbase[1][35:N] | gbus.addr[N - 1:0];
if(PCI.hit[2])
gbus.addr = pgbase[2][35:P] | gbus.addr[P - 1:0];
if(PCI.hit[3])
gbus.addr = pgbase[3][35:P] | gbus.addr[Q - 1:0];
PCI base reg.
Pulled from inside core.
PCI.hit[0]
PCI.hit[1]
PCI.hit[2]
PCI.I/O.hit[0]
valid.cmd
gdata[63:0]
Tar.cmd[3:0]
Tar.Addr
Membase[2]
pgbase[2]
Main memory:
pgbase[1]
Summary of Contents for TMPR7901
Page 1: ...TX System RISC TX79 Family TMPR7901 Symmetric 2 way superscalar 64 bit CPU ...
Page 14: ...Handling Precautions ...
Page 15: ......
Page 17: ...1 Using Toshiba Semiconductors Safely 1 2 ...
Page 41: ...4 Precautions and Usage Considerations 4 2 ...
Page 42: ...TX7901 User s Manual Rev 6 30T November 2001 DOCUMENT NUMBER M 99 00004 07 ...
Page 43: ......
Page 259: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 1 13 Removed ...
Page 260: ...Chapter 13 Removed TX7901 User s Manual Rev 6 30T Nov 2001 13 2 ...