Intel® IXP42X Product Line of Network Processors and IXC1100 Control Plane Processor
September 2006 DM
Order Number: 252480-006US 135
Intel XScale® Processor—Intel® IXP42X product line and IXC1100 control plane processors

3.7.2.3 Performance Monitor Control Register

(PMNC)

The performance monitor control register (PMNC) is a coprocessor register that:

Contains the PMU ID

Extends CCNT counting by six more bits (cycles between counter rollover = 238)

Resets all counters to zero

And enables the entire mechanism

Tabl e 56 shows the format of the PMNC register.

Table 55. Performance Monitor Count Register (PMN0 - PMN3)

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9876543210
Event Counter
reset value: unpredictable
Bits Access Description
31:0 Read / Write
32-bit event counter - Reset to ‘0’ by PMNC register.
When an event counter reaches its maximum value
0xFFFF,FFFF, the next event it needs to count will cause it
to roll over to zero and generate an interrupt request if
enabled.

Table 56. Performance Monitor Control Register

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9876543210
ID DCPE
reset value: E and ID are 0, others unpredictable
Bits Access Description
31:24 Read / Write Ignored Performance Monitor Identification (ID) -
Intel® IXP42X product line and IXC1100 control plane
processors = 0x14
23:4 Read-unpredictable / Write-as-0 Reserved
3Read / Write Clock Counter Divider (D) -
0 = CCNT counts every processor clock cycle
1 = CCNT counts every 64th processor clock cycle
2 Read-unpredictable / Write Clock Counter Reset (C) -
0 = no action
1 = reset the clock counter to ‘0x0’
1 Read-unpredictable / Write Performance Counter Reset (P) -
0 = no action
1 = reset all performance counters to ‘0x0’
0Read / Write Enable (E) -
0 = all counters are disabled
1 = all counters are enabled