Intel GD82559ER manual General Control Register, General Status Register

			Networking Silicon — GD82559ER
		Table 11. Power Management Driver Register
Bits	Default	Read/Write	Description
29	0b	Read/Clear	Interesting Packet. This bit is set when an “interesting” packet is
			received. Interesting packets are defined by the 82559ER packet
			filters. This bit is cleared by writing 1b to it.
28:26	000b	Read Only	Reserved. These bits are reserved and should be set to 000b.
25	0b	Read/Clear	Reserved. These bit is reserved and should be set to 0b.
24	0b	Read/Clear	PME Status. This bit is a reflection of the PME Status bit in the Power
			Management Control/Status Register (PMCSR). It is set upon a wake-
			up event and is independent of the PME Enable bit.
			This bit is cleared by writing 1b to it. This also clears the PME Status
			bit in the PMCSR and de-asserts the PME signal. I

Note: The PMDR is initialized at ALTRST# reset only.

8.1.12General Control Register

The General Control register is a byte register and is described below.

			Table 12. General Control Register
Bits	Default	Read/Write	Description
7:2	000000b	Read Only	Reserved. These bits are reserved and should be set to 000000b.
1	0b	Read/Write	Deep Power-Down on Link Down Enable. If a 1b is written to this
			field, the 82559ER may enter a deep power-down state (sub-3 mA) in
			the D2 and D3 power states while the link is down.
			In this state, the 82559ER does not keep link integrity. This state is not
			supported for point-to-point connection of two end stations.
0	0b	Read/Write	Clockrun Signal Disable. If this bit is set to 1b, then the 82559ER will
			always request the PCI clock signal. This mode can be used to
			overcome potential receive overruns caused by Clockrun signal
			latencies over 5 μs.

8.1.13General Status Register

The General Status register is a byte register which indicates the link status of the 82559ER.

			Table 13. General Status Register
Bits	Default	Read/Write	Description
7:3	00000b	Read Only	Reserved. These bits are reserved and should be set to 00000b.
2	--	Read Only	Duplex Mode. This bit indicates the wire duplex mode: full duplex (1b)
			or half duplex (0b).
1	--	Read Only	Speed. This bit indicates the wire speed: 100 Mbps (1b) or 10 Mbps
			(0b).
0	0b	Read Only	Link Status Indication. This bit indicates the status of the link: valid
			(1b) or invalid (0b).

Datasheet 61