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4.44 Power Management Control/Status Register
The power management control/status register determines and changes the current power state of the
PCI7x21/PCI7x11 CardBus function. The contents of this register are not affected by the internally generated reset
caused by the transition from the D3
hot
to D0 state. See Table 4−20 for a complete description of the register contents.
All PCI registers, ExCA registers, and CardBus registers are reset as a result of a D3
hot
-to-D0 state transition, with
the exception of the PME
context bits (if PME is enabled) and the GRST only bits.
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Name Power management control/status
Type RWC R R R R R R RW R R R R R R RW RW
Default 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Register: Power management control/status
Offset: A4h (Functions 0, 1)
Type: Read-only, Read/Write, Read/Write/Clear
Default: 0000h
Table 4−20. Power Management Control/Status Register Description
BIT SIGNAL TYPE FUNCTION
15 † PMESTAT RC
PME status. This bit is set when the CardBus function would normally assert the PME signal, independent
of the state of the PME_EN bit. This bit is cleared by a writeback of 1, and this also clears the PME
signal
if PME
was asserted by this function. Writing a 0 to this bit has no effect.
14−13 DATASCALE R This 2-bit field returns 0s when read. The CardBus function does not return any dynamic data.
12−9 DATASEL R Data select. This 4-bit field returns 0s when read. The CardBus function does not return any dynamic data.
8 ‡ PME_ENABLE RW
This bit enables the function to assert PME. If this bit is cleared, then assertion of PME is disabled. This
bit is not cleared by the assertion of PRST
. It is only cleared by the assertion of GRST.
7−2 RSVD R Reserved. These bits return 0s when read.
1−0 PWRSTATE RW
Power state. This 2-bit field is used both to determine the current power state of a function and to set the
function into a new power state. This field is encoded as:
00 = D0
01 = D1
10 = D2
11 = D3
hot
†
One or more bits in this register are PME context bits and can be cleared only by the assertion of GRST
when PME is enabled. If PME is not
enabled, then this bit is cleared by the assertion of PRST
or GRST.
‡
This bit is cleared only by the assertion of GRST
.