System Control Coprocessor
ARM DDI 0363E Copyright ©2009 ARM Limited. All rights reserved. 4-63
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On reads, this register returns the current setting. On writes, interrupt requests can be enabled.
If an interrupt request has been enabled it is disabled by writing to the nVAL IRQ Enable Clear
Register, see c15, nVAL IRQ Enable Clear Register on page4-65.
If one or more of the IRQ request fields (P2, P1, P0, and C) is enabled, and the corresponding
counter overflows, then an IRQ request is indicated by nVALIRQ being asserted LOW. This
signal might be passed to a system interrupt controller.
c15, nVAL FIQ Enable Set Register
The nVAL FIQ Enable Set Register enables any of the PMC Registers, PMC0-PMC2, and
CCNT, to generate an fast interrupt request on overflow. If enabled, the interrupt request is
signaled by nVALFIQ being asserted LOW.
The nVAL FIQ Enable Set Register is:
• A read/write register.
• Always accessible in Privileged mode. The USEREN Register determines access, see c9,
User Enable Register on page 6-15.
Figure 4-45 shows the bit arrangement for the nVAL FIQ Enable Set Register.
Figure 4-45 nVAL FIQ Enable Set Register format
Table4-43 shows how the bit values correspond with the nVAL FIQ Enable Set Register.
To access the FIQ Enable Set Register, read or write CP15 with:
MRC p15, 0, <Rd>, c15, c1, 1 ; Read FIQ Enable Set Register
MCR p15, 0, <Rd>, c15, c1, 1 ; Write FIQ Enable Set Register
On reads, this register returns the current setting. On writes, interrupt requests can be enabled.
If an interrupt request has been enabled it is disabled by writing to the FIQ Enable Clear
Register, see c15, nVAL FIQ Enable Clear Register on page4-66.
If one or more of the FIQ request fields (P2, P1, P0, and C) is enabled, and the corresponding
counter overflows, then an FIQ request is indicated by nVALFIQ being asserted LOW. This
signal can be passed to a system interrupt controller.
C
31 3210
Reserved
P2
P1
P0
Performance monitor counter
overflow FIQ request enables
Cycle count overflow FIQ request enable
Table4-43 nVAL FIQ Enable Set Register bit functions
Bits Field Function
[31] C CCNT overflow FIQ request
[30:3] Reserved UNP or SBZP
[2] P2 PMC2 overflow FIQ request
[1] P1 PMC1 overflow FIQ request
[0] P0 PMC0 overflow FIQ request