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82801AA and 82801AB Datasheet
13-15
AC ’97 Modem Controller Registers (D31:F6)
NOTE:
On reads from a codec, the controller will give the codec a maximum of 4 frames to respond. If no
response is received, the controller returns a dummy read completion to the processor (with all F’s on
the data) and also sets the Read Completion Status bit in the Global Status Register.
13.2.10
CAS—Codec Access Semaphore Register
I/O Address:
Default Value:
Lockable:
NABMBAR + 44h
00h
No
Attribute:
Size:
Power Well:
R/W
8 bits
Core
11
Secondary Resume Interrupt.
This bit indicates that a resume event occurred on SIDN[1].
1 = Resume event occurred
0 = Cleared by writing a 1 to this bit position.
10
Primary Resume Interrupt.
This bit indicates that a resume event occurred on SDIN[0].
1 = Resume event occurred
0 = Cleared by writing a 1 to this bit position.
9
Secondary Codec Ready (SCR).
Reflects the state of the codec ready bit in SDIN[1]. Bus masters
ignore the condition of the codec ready bits. Software must check this bit before starting the bus
masters. Once the codec is “ready”, it must never go “not ready” spontaneously.
8
Primary Codec Ready (PCR).
Reflects the state of the codec ready bit in SDIN[0]. Bus masters
ignore the condition of the codec ready bits. Software must check this bit before starting the bus
masters. Once the codec is “ready”, it must never go “not ready” spontaneously.
7
Mic In Interrupt (MINT).
This bit indicates that one of the Mic in channel interrupts occurred.
1 = Interrupt occurred.
0 = When the specific interrupt is cleared, this bit is cleared.
6
PCM Out Interrupt (POINT).
This bit indicates that one of the PCM out channel interrupts occurred.
1 = Interrupt occurred.
0 = When the specific interrupt is cleared, this bit is cleared.
5
PCM In Interrupt (PIINT).
This bit indicates that one of the PCM in channel interrupts occurred.
1 = Interrupt occurred.
0 = When the specific interrupt is cleared, this bit is cleared.
4:3
Reserved
2
Modem Out Interrupt (MOINT)
. This bit indicates that one of the modem out channel interrupts
occurred.
1 = Interrupt occurred.
0 = When the specific interrupt is cleared, this bit is cleared.
1
Modem In Interrupt (MIINT)
. This bit indicates that one of the modem in channel interrupts
occurred.
1 = Interrupt occurred.
0 = When the specific interrupt is cleared, this is cleared.
0
GPI Status Change Interrupt (GSCI).
This bit is set whenever bit 0 of slot 12 is set. This happens
when the value of any of the GPIOs currently defined as inputs changes.
1 = Input changed.
0 = Cleared by writing a 1 to this bit position.
Bit
Description
Bit
Description
7:1
Reserved.
0
Codec Access Semaphore (CAS)
: This bit is read by software to check whether a codec access is
currently in progress.
1 = The act of reading this register sets this bit to 1. The driver that read this bit can then perform an
I/O access. Once the access is completed, hardware automatically clears this bit.
0 = No access in progress.