82801DB Datasheet, PDF (501/587 Pages) Intel Corporation – Intel 82801DB I/O Controller Hub 4 (ICH4)

AC ’97 Modem Controller Registers (D31:F6)
15.2 AC ’97 Modem I/O Space (D31:F6)
In the case of the split codec implementation, accesses to the modem mixer registers in different
codecs are differentiated by the controller by using address offsets 00h – 7Fh for the primary codec
and address offsets 80h – FEh for the secondary codec. Table 15-2 shows the register addresses for
the modem mixer registers.
Table 15-2. Intel^® ICH4 Modem Mixer Register Configuration
Register
Pri.
00h:38h
3Ch
3Eh
40h
42h
44h
46h
48h
4Ah
4Ch
4Eh
50h
52h
54h
56h
58h
5Ah
7Ch
7Eh
Sec.
80h:B8h
BCh
BEh
C0h
C2h
C4h
C6h
C8h
CAh
CCh
CEh
D0h
D2h
D4h
D6h
D8h
DAh
FCh
FEh
MMBAR Exposed Registers (D31:F6)
Intel RESERVED
Extended Modem ID
Extended Modem Stat/Ctrl
Line 1 DAC/ADC Rate
Line 2 DAC/ADC Rate
Handset DAC/ADC Rate
Line 1 DAC/ADC Level Mute
Line 2 DAC/ADC Level Mute
Handset DAC/ADC Level Mute
GPIO Pin Config
GPIO Polarity/Type
GPIO Pin Sticky
GPIO Pin Wake Up
GPIO Pin Status
Misc. Modem AFE Stat/Ctrl
AC ’97 Reserved
Vendor Reserved
Vendor ID1
Vendor ID2
NOTES:
1. Registers in italics are for functions not supported by the ICH4.
2. Software should not try to access reserved registers.
3. The ICH4 supports a modem codec connected to AC_SDIN[2:0], as long as the Codec ID is 00 or 01.
However, the ICH4 does not support more than one modem codec. For a complete list of topologies, see the
appropriate chipset Platform Design Guide.
The Global Control (GLOB_CNT) and Global Status (GLOB_STA) registers are aliased to the
same global registers in the audio and modem I/O space. Therefore, a read/write to these registers
in either audio or modem I/O space affects the same physical register. S/W could access these
registers as bytes, word, or DWord quantities, but reads must not cross DWord boundaries.
These registers exist in I/O space and reside in the AC ‘97 controller. The two channels, Modem in
and Modem out, each have their own set of Bus Mastering registers. The following register
descriptions apply to both channels. The naming prefix convention used is as follows:
MI = Modem in channel
MO = Modem out channel
Intel^® 82801DB ICH4 Datasheet
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