Cyclone® V Avalon® Streaming (Avalon-ST) Interface for PCIe* Solutions User Guide

ID 683524
Date 6/02/2020
Public
Document Table of Contents

4.11. Power Management Signals

Table 36.  Power Management Signals

Signal

Direction

Description

pme_to_cr

Input

Power management turn off control register.

Root Port—When this signal is asserted, the Root Port sends the PME_turn_off message.

Endpoint—This signal is asserted to acknowledge the PME_turn_off message by sending pme_to_ack to the Root Port.

pme_to_sr

Output

Power management turn off status register.

Root Port—This signal is asserted for 1 clock cycle when the Root Port receives the pme_turn_off acknowledge message.

Endpoint—This signal is asserted for 1 cycle when the Endpoint receives the PME_turn_off message from the Root Port.

pm_event

Input

Power Management Event. This signal is only available for Endpoints.

The Endpoint initiates a a power_management_event message (PM_PME) that is sent to the Root Port. If the Hard IP is in a low power state, the link exits from the low-power state to send the message. This signal is positive edge-sensitive.

pm_event_func[2:0]

Input

Specifies the function associated with a Power Management Event.
pm_data[9:0]

Input

Power Management Data.

This bus indicates power consumption of the component. This bus can only be implemented if all three bits of AUX_power (part of the Power Management Capabilities structure) are set to 0. This bus includes the following bits:

  • pm_data[9:2]: Data Register: This register maintains a value associated with the power consumed by the component. (Refer to the example below)
  • pm_data[1:0]: Data Scale: This register maintains the scale used to find the power consumed by a particular component and can include the following values:
  • 2b’00: unknown
  • 2b’01: 0.1 ×
  • 2b’10: 0.01 ×
  • 2b’11: 0.001 ×

For example, the two registers might have the following values:

  • pm_data[9:2]: b’1110010 = 114
  • pm_data[1:0]: b’10, which encodes a factor of 0.01

To find the maximum power consumed by this component, multiply the data value by the data Scale (114 × .01 = 1.14). 1.14 watts is the maximum power allocated to this component in the power state selected by the data_select field.

pm_auxpwr

Input

Power Management Auxiliary Power: This signal can be tied to 0 because the L2 power state is not supported.

Figure 19. Layout of Power Management Capabilities Register
Table 37.   Power Management Capabilities Register Field Descriptions

Bits

Field

Description

[31:24]

Data register

This field indicates in which power states a function can assert the PME# message.

[23:16]

reserved

[15]

PME_status

When set to 1, indicates that the function would normally assert the PME# message independently of the state of the PME_en bit.

[14:13]

data_scale

This field indicates the scaling factor when interpreting the value retrieved from the data register. This field is read-only.

[12:9]

data_select

This field indicates which data should be reported through the data register and the data_scale field.

[8]

PME_EN

1: indicates that the function can assert PME#0: indicates that the function cannot assert PME#

[7:2]

reserved

[1:0]

PM_state

Specifies the power management state of the operating condition being described. The following encodings are defined:

  • 2b’00 D0
  • 2b’01 D1
  • 2b’10 D2
  • 2b’11 D3

A device returns 2b’11 in this field and Aux or PME Aux in the type register to specify the D3-Cold PM state. An encoding of 2b’11 along with any other type register value specifies the D3-Hot state.

Figure 20. pme_to_sr and pme_to_cr in an Endpoint IP core The following figure illustrates the behavior of pme_to_sr and pme_to_cr in an Endpoint. First, the Hard IP receives the PME_turn_off message which causes pme_to_sr to assert. Then, the Application Layer sends the PME_to_ack message to the Root Port by asserting pme_to_cr.