6–48
Chapter 6: IP Core Interfaces
Power Management Signals
Arria V GZ Hard IP for PCI Express
November 2012
Altera Corporation
describes the use of the various fields of the Power Management
Capabilities register.
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
.
Table 6–24. 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
.
[22:16]
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 6–38. pme_to_sr and pme_to_cr in an Endpoint IP core
pme_to_sr
pme_to_cr
hard
IP