
124
Functional Operation
Chapter 3
AMD-8111 HyperTransport I/O Hub Data Sheet
24674
Rev. 3.00
April 2003
AMD Preliminary Information
Delay Time field are loaded into an internal interrupt event timer, and the interrupt event timer is
disabled. Each time a receive or transmit interrupt event that is included in that group occurs, the
interrupt event counter is decremented by 1 and the interrupt event timer is enabled, or if it has
already been enabled, it continues to count down. Once the interrupt event timer has been enabled, it
decrements by 1 every 10 microseconds.
When either the interrupt event counter or the interrupt event timer reaches zero, the PIRQA_L pin is
asserted.
3.10.16
Power Management Support
The network controller supports power management as defined in the PCI Bus Power Management
Interface Specification V1.1 and Network Device Class Power Management Reference Specification
V1.0. These specifications define the network device power states, PCI power management interface
including the Capabilities Data Structure and power management registers block definitions, power
management events, and OnNow network Wake-up events.
The general scheme for the network controller power management is that when a wake-up event is
detected, a signal (PME_L) is generated to cause hardware external to the network controller to put
the computer into the working (S0) mode. The controller supports three types of wake-up events:
Magic Packet Frame Detect
Link State Change
Pattern Match Detect
All three wake-up events can cause wake-up from any power state including D3
cold
(PCI bus power
off and clock stopped).
3.10.16.1
OnNow Wake-Up Sequence
The system software enables the PME_L signal by setting the PME_EN bit in the PMCSR register
(PCI configuration registers, offset 44h, bit 8) to 1. When a Wake-up event is detected, the network
controller sets the PME_STATUS bit in the PMCSR register (PCI configuration registers, offset 44h,
bit 15). Setting this bit causes the PME_L signal to be asserted.
Assertion of the PME_L signal causes external hardware to wake up the CPU. The system software
then reads the PMCSR register of every PCI device in the system to determine which device asserted
the PME_L signal.
When the software determines that the signal came from the network controller, it writes to the
device's PMCSR to put the device into power state D0. The software then writes a 1 to the
PME_STATUS bit to clear the bit and turn off the PME_L signal, and it calls the device's software
driver to tell it that the device is now in state D0. The system software can clear the PME_STATUS bit
either before, after, or at the same time that it puts the device back into the D0 state.