Am79C973/Am79C975
121
P R E L I M I N A R Y
PCI Power Management Capabilities Register
(PMC)
Offset 42h
Note:
All bits of this register are loaded from
EEPROM. The register is aliased to BCR36 for testing
purposes.
Bit
Name
Description
15-11
PME_SPT
PME Support. This 5-bit field indi-
cates the power states in which
the function may assert PME. A
value of 0b for any bit indicates
that the function is not capable of
asserting the PME signal while in
that power state.
Bit(11) XXXX1b - PME can be
asserted from D0.
Bit(12) XXX1Xb - PME can be
asserted from D1.
Bit(13) XX1XXb - PME can be
asserted from D2.
Bit(14) X1XXXb - PME can be
asserted from D3hot.
Bit(15) 1XXXXb - PME can be
asserted from D3cold.
Read only.
Bit 15 of the PMC register indi-
cates that the controller is capa-
ble of generating PME from the
D3 cold state. This capability de-
pends on the presence of auxilia-
ry power, as indicated by the
AUXDET input. The capability
can be disabled by loading a zero
into bit 15 of BCR36 from the EE-
PROM. (This register is aliased to
the PMC register.)
10
D2_SPT
D2 Support. If this bit is a 1, this
function supports the D2 Power
Management State.
Read only.
9
D1_SPT
D1 Support. If this bit is a 1, this
function supports the D1 Power
Management State.
Read only.
8-6
RES
Reserved locations. Written as
zeros and read as undefined.
5
DSI
Device
When this bit is 1, it indicates that
special initialization of the func-
tion is required (beyond the stan-
dard PCI configuration header)
before the generic class device
driver is able to use it.
Specific
Initialization.
Read only.
4
RES
Reserved locations. Written as
zeros and read as undefined.
3
PME_CLK
PME Clock. When this bit is a 1,
it indicates that the function relies
on the presence of the PCI clock
for PME operation. When this bit
is a 0 it indicates that no PCI
clock is required for the function
to generate PME.
Functions that do not support
PME generation in any state
must return 0 for this field.
Read only.
2-0
PMIS_VER Power Management Interface
Specification Version. A value of
001b indicates that this function
complies with the revision 1.1 of
the PCI Power Management In-
terface Specification.
PCI Power Management Control/Status Register
(PMCSR)
Offset 44h
Bit
Name
Description
15
PME_STATUS PME Status. This bit is set when
the function would normally as-
sert the PME signal independent
of the state of the PME_EN bit.
Writing a 1 to this bit will clear it
and cause the function to stop as-
serting a PME (if enabled). Writ-
ing a 0 has no effect.
If the function supports PME from
D3cold then this bit is sticky and
must be explicitly cleared by the
operating system each time the
operating system is initially load-
ed.