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Intel 8255x 10/100 Mbps Ethernet Controller Family Open Source Software Developer Manual 19
PCI Interface
4.1.18.4 Power Management Control/Status (Offset E0)
The Power Management Control/Status Register (PMCSR) is used to determine and change the
current power state of the device. It also allows for the control of the power management interrupts
in a standard way. Since power management is not implemented in the 82557, this register is hard-
coded to 0 for that device. For the 82558 and later devices this register acts according to the chart
below.
23 0 RO Reserved. This field is not used by the 8255x.
22
82558: 0
82559:
no auxiliary power
- 0
with auxiliary
power - 1
RO
AUX_Current. If the device is connected to an auxiliary power
supply, the 82559 reports a “1” to indicate that it consume less than
250 mA from the 3.3 Vaux pin while in the D3
cold
state. This bit is a
reflection of bit 31.
21 1 RO
DSI. The Device Specific Initialization bit indicates whether special
initialization of this function is required (beyond the standard PCI
configuration header) before the generic class device driver is able
to use it. Device specific initialization is required for the 82558 and
82559 after a D3 to D0 transition.
20
82558A: 0
82558B, 82559:
no auxiliary power
- 0
with auxiliary
power - 1
RO
Auxiliary Power Source
This bit is only meaningful if PMCSR bit 31 (D3
cold
supporting
PME) equals 1. When this bit also equals 1, it indicates that support
for PME# in D3
cold
requires an auxiliary power supply. The 82558
B-step and 82559 require auxiliary power for wake up from the
D3
cold
state. Therefore this bit is set to 1 if auxiliary power is
present.
19 0 RO
PME Clock. When this bit is 1, it indicates that the PME#
generation logic requires its host PCI bus to maintain a free-running
PCI clock. When this bit is 0, it indicates that no host bus clock is
required for the function to generate PME#. The 82558 and later
generation devices do not require a clock to generate PME# and
return 0.
81:16 001 RO
Version. This field specifies to software how to interpret the PMC
and PMCSR registers. A value of 001b indicates that the device
complies with the Revision 1.0 of the PCI Power Management
Interface Specification.
Table 4. Power Management Capabilities
Bit Default Value R / W Description