Technical information

7-30
AIC-6915 Ethernet LAN Controller Programmer’s Manual
The following interrupts are affected by the masking time:
■
RxQ1DoneInt
■
EarlyRxQ1Int
■
RxQ2DoneInt
■
EarlyRxQ2Int
■
TxDmaDoneInt
■
TxQueueDoneInt
■
TxFrameCompleteInt
CurrentTime Register
Type: R/W
Internal Registers Subgroup: Ethernet Functional Registers
Byte Address: 78h - 7Bh
4:0 r/w 0
IntMaskPeriod:
Specifies a minimum amount of time between two
consecutive assertions of external PCI interrupt (
PCI_INTA_
) as a
result of the interrupt status bits
T
X
D
ONE
I
NT
and
R
X
D
ONE
I
NT
, if
the corresponding bits
T
X
D
ELAY
D
ISABLE
and
R
X
D
ELAY
D
ISABLE
are
at their reset state, ‘0’. When the software driver writes a ‘01’ or ‘11’
to
I
NT
M
ASK
M
ODE
, the AIC-6915 loads the interrupt masking timer
and prevents the interrupt status bits
T
X
D
ONE
I
NT
and
R
X
D
ONE
I
NT
from causing a PCI interrupt for a period defined by
IntMaskPeriod
. The number loaded to the timer is
IntMaskPeriod
*128. The following samples of masking periods are
calculated based on
TimerClockPeriod
=0.8usec:
‘
00000
’ - Timer in terminal count state - no masking.
‘
00001
’ - 128 TimerClock periods, 0.1024mSec
‘
10000
’ - 2048 TimerClock periods, 1.6384mSec
‘
11111
’ - 4095 TimerClock periods, 3.2760mSec
Note:
Interrupts resulting from irregular operations, such as error
reporting, are not affected by the interrupt mask timer operation.
Table 7-41. CurrentTime Register
Bit(s) rw
Reset
value Description/Function
31:0 r/w 0
CurrentTime:
This field is a 32-bit counter clocked by
TimerClock
.
If
TimerClock
period is 0.8
µ
s, then the range of
CurrentTime
is ~60
Min. The driver can load the register anytime in order to
synchronize the current time of two adapter cards. This counter is
used for time stamp purposes.
Table 7-40. TimersControl Register (Continued)
Bit(s) rw
Reset
value Description/Function