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Programmer’s Reference Manual 99
AC ’97 Modem Controller Registers (D30:F3)
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
NOTE:
1. MI = Modem in channel; MO = Modem out channel
Note: Internal reset as a result of D3
HOT
to D0 transition will reset all the core well registers except the
registers shared with the AC ’97 audio controller (GCR, GSR, CASR). All resume well registers
will not be reset by the D3
HOT
to D0 transition.
Core well registers and bits not reset by the D3
HOT
to D0 transition:
• offset 3Ch–3Fh – bits [6:0] Global Control (GLOB_CNT)
• offset 40h–43h – bits [29,15,11:10] Global Status (GLOB_STA)
• offset 44h – Codec Access Semaphore Register (CAS)
Resume well registers and bits will not be reset by the D3
HOT
to D0 transition:
• offset 40h–43h – bits [17:16] Global Status (GLOB_STA)
Table 3-3. Modem Registers
Offset Mnemonic Name Default Access
00h–03h MI_BDBAR
Modem In Buffer Descriptor List Base
Address
00000000h R/W
04h MI_CIV Modem In Current Index Value 00h RO
05h MI_LVI Modem In Last Valid Index 00h R/W
06h–07h MI_SR Modem In Status 0001h R/WC, RO
08h–09h MI_PICB Modem In Position In Current Buffer 0000h RO
0Ah MI_PIV Modem In Prefetch Index Value 00h RO
0Bh MI_CR Modem In Control 00h
R/W,
R/W (special)
10h–13h MO_BDBAR
Modem Out Buffer Descriptor List Base
Address
00000000h R/W
14h MO_CIV Modem Out Current Index Value 00h RO
15h MO_LVI Modem Out Last Valid 00h R/W
16h–17h MO_SR Modem Out Status 0001h R/WC, RO
18h–19h MI_PICB Modem In Position In Current Buffer 0000h RO
1Ah MO_PIV Modem Out Prefetched Index 00h RO
1Bh MO_CR Modem Out Control 00h
R/W,
R/W (special)
3Ch–3Fh GLOB_CNT Global Control 00000000h
R/W,
R/W (special)
40h–43h GLOB_STA Global Status 00300000h
RO, R/W,
R/WC
44h CAS Codec Access Semaphore 00h R/W (special)