82801DB Datasheet, PDF (431/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

EHCI Controller Registers (D29:F7)
Bit
Description
SMI on Periodic Enable — R/W.
3 0 = Disable
1 = Enable. When this bit is 1 and SMI on Periodic is 1, then the host controller will issue an SMI.
SMI on CF Enable — R/W.
2 0 = Disable
1 = Enable. When this bit is 1 and SMI on CF is 1, then the host controller will issue an SMI.
SMI on HCHalted Enable — R/W.
1
0 = Disable
1 = Enable. When this bit is a 1 and SMI on HCHalted is 1, then the host controller will issue an
SMI.
SMI on HCReset Enable — R/W.
0
0 = Disable
1 = Enable. When this bit is a 1 and SMI on HCReset is 1, then host controller will issue an SMI—
R/W.
12.1.29
ACCESS_CNTL—Access Control Register
(USB EHCI—D29:F7)
Address Offset: 80h
Default Value:
00h
Attribute: R/W
Size:
8 bits
Bit
Description
7:1 Reserved
WRT_RDONLY — R/W.
0 = Disable
1 = Enables a select group of normally read-only registers in the EHC function to be written by
0
software. Registers that may only be written when this mode is entered are noted in the
summary tables and detailed description as “Read/Write-Special”. The registers fall into two
categories:
- System-configured parameters, and
- Status bits
12.1.30 HS_Ref_V—USB HS Reference Voltage Register
(USB EHCI—D29:F7)
Offset Address:
Default Value:
Lockable:
DC–DFh
00000000h
No
Attribute:
Size:
Power Well:
R/W
32 bit
Resume
Bit
31:22
21:16
15:0
Description
Reserved— RO.
USB HS Ref Voltage — RW. BIOS should always program this register to the recommended value
of 111111. All other values are reserved
Reserved— RO.
Intel^® 82801DB ICH4 Datasheet
431