82801DB Datasheet, PDF (433/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

EHCI Controller Registers (D29:F7)
12.2.1.2
HCIVERSION—Host Controller Interface Version Number Register
Offset:
Default Value:
02–03h
0100h
Attribute: RO
Size:
16 bits
Bit
Description
15:0
This is a two-byte register containing a BCD encoding of the version number of interface that this
host controller interface conforms.
12.2.1.3
HCSPARAMS—Host Controller Structural Parameters Register
Offset:
Default Value:
04–07h
00103206h
Attribute: R/W-Special
Size:
32 bits
Note: This register is reset by a suspend well reset and not a D3-to-D0 reset or HCRESET.
Bit
Description
31:24
23:20
19:17
16
15:12
11:8
7:4
3:0
Reserved — RO. Default=0h.
Debug Port Number (DP_N) — R/W-Special. Hardwired to 1h; indicates that the Debug Port is on
the lowest numbered port on the ICH4.
Reserved
Reserved. Should be written to 0.
Number of Companion Controllers (N_CC) — R/W-Special. This field indicates the number of
companion controllers associated with this USB ECHI host controller.
A 0h in this field indicates there are no companion host controllers. Port-ownership hand-off is not
supported. Only high-speed devices are supported on the host controller root ports.
A value larger than 1 in this field indicates there are companion USB UHCI host controller(s). Port-
ownership hand-offs are supported. High, Full- and Low-speed devices are supported on the host
controller root ports.
The ICH4 allows the default value of 3h to be over-written by BIOS. Since the ICH4 cannot support
more than 3 companion host controllers, bits 15:14 are implemented as read-only 00b. When
removing classic controllers, they should be disabled in the following order: Function 2, Function 1,
and Function 0, which correspond to ports 5:4, 3:2, and 1:0, respectively.
Number of Ports per Companion Controller (N_PCC) — RO. Hardwired to 0010. This field indicates
the number of ports supported per companion host controller. It is used to indicate the port routing
configuration to system software.
Reserved. These bits are reserved and default to 0h.
N_PORTS — R/W-Special. This field specifies the number of physical downstream ports
implemented on this host controller. The value of this field determines how many port registers are
addressable in the Operational Register Space. Valid values are in the range of 1h to Fh. The default
is 0110 (6h). However, software may write a value less than 6 for some platform configurations. A 0h
in this field is undefined. Bit 3 is always hardwired to 0.
NOTE: This register is writable when the WRT_RDONLY bit is set.
Intel^® 82801DB ICH4 Datasheet
433