307013-003 Datasheet, PDF (624/848 Pages) Intel Corporation – Intel I/O Controller Hub 7

AC ’97 Audio Controller Registers (D30:F2) (Desktop and Mobile Only)
16.1.10 NAMBAR—Native Audio Mixer Base Address Register
(Audio—D30:F2)
Address Offset: 10–13h
Default Value: 00000001h
Lockable:
No
Attribute:
Size:
Power Well:
R/W, RO
32 bits
Core
The Native PCI Mode Audio function uses PCI Base Address register #1 to request a
contiguous block of I/O space that is to be used for the Native Audio Mixer software
interface. The mixer requires 256 bytes of I/O space. Native Audio Mixer and Modem
codec I/O registers are located from 00h to 7Fh and reside in the codec. Access to
these registers will be decoded by the AC '97 controller and forwarded over the AC-link
to the codec. The codec will then respond with the register value.
In the case of the split codec implementation, accesses to the 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.
Note:
The tertiary codec cannot be addressed via this address space. The tertiary space is
only available from the new MMBAR register. This register powers up as read only and
only becomes write-able when the IOSE bit in offset 41h is set.
For description of these I/O registers, refer to the Audio Codec ‘97 Component
Specification, Version 2.3.
Bit
Description
31:16 Hardwired to 0s.
15:8
Base Address — R/W. These bits are used in the I/O space decode of the Native Audio
Mixer interface registers. The number of upper bits that a device actually implements
depends on how much of the address space the device will respond to. For the AC ‘97
mixer, the upper 16 bits are hardwired to 0, while bits 15:8 are programmable. This
configuration yields a maximum I/O block size of 256 bytes for this base address.
7:1 Reserved. Read as 0s.
Resource Type Indicator (RTE) — RO. This bit defaults to 0 and changes to 1 if the
0 IOSE bit is set (D30:F2:Offset 41h, bit 0). When 1, this bit indicates a request for I/O
space.
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Intel ^® ICH7 Family Datasheet