
Chapter 4
Registers
249
24674
Rev. 3.00
April 2003
AMD-8111 HyperTransport I/O Hub Data Sheet
AMD Preliminary Information
SMBus Host Address Register
PME4
Default:
0000h.
Attribute:
Read-write.
SMBus Host Data Register
PME6
Default:
0000h.
Attribute:
Read-write.
SMBus Host Command Field Register
PME8
Default:
00h.
Attribute:
Read-write.
SMBus Host Block Data FIFO Access Port
PME9
Default:
00h.
Attribute:
See below.
Bits
15:8
Description
HST10BA. Host 10-bit address LSBs.
This
fi
eld stores the second byte of the address, used in 10-
bit SMBus host-as-master transfers. If HSTADDR == 1111_0XXb, then the cycle is speci
fi
ed to use
10-bit addressing. If HSTADDR is any other value, then HST10BA is not utilized.
HSTADDR. Host cycle address.
This speci
fi
es the 7-bit address to the SMBus generated by the host
(as a master) during SMBus cycles that are initiated by PME2[HOSTST].
READCYC. Host read (High) write (Low) cycle.
1=Speci
fi
es that the cycle generated by a write to
PME2[HOSTST] is a read or receive command. 0=Cycle is a write or send command.
7:1
0
Bits
15:0
Description
HSTDATA. Host cycle data.
This register is written to by software to specify the data to be passed to
the SMBus during write and send cycles. It is read by software to specify the data passed to host
controller by the SMBus during read and receive cycles. Bit[0] speci
fi
es the data written or read
during the quick command cycle. Bits[7:0] specify the data for byte read and write cycles, send byte
cycles, and receive byte cycles. Bits[15:0] are used for word read and write cycles and process calls.
Bits[5:0] are used to specify the count for block read and write cycles.
Bits
7:0
Description
HSTCMD. Host cycle command.
This speci
fi
es the command
fi
eld passed to the SMBus by the host
controller during read byte, write byte, read word, write word, process call, block read, and block write
cycles. Host cycles are initiated by PME2[HOSTST].
Bits
7:0
Description
HSTFIFO. Host block read-write FIFO.
For block write commands, software loads 1 to 32 bytes into
this port before sending them to the SMBus through the PME2[HOSTST] command. For block read
commands, software reads 1 to 32 bytes from this port after the block read cycle is complete. If,
during a block read or write, an error occurs, then the FIFO is
fl
ushed by the hardware. Read and
write accesses to this port while the host is busy (PME0[HST_BSY]) are ignored.