System Integration Unit

Interrupt Controller FIQ Pending Register (ICFP) contains the interrupts from all sources that can generate an FIQ interrupt. The Interrupt Controller Level register (ICLR) is programmed to send interrupts to the ICFP to generate an FIQ.

The second level uses registers contained in the source device (the device generating the first- level interrupt bit). The second-level interrupt status gives additional information about the interrupt and is used inside the interrupt service routine. In general, multiple second-level interrupts are OR’ed to produce a first-level interrupt bit.

In most cases, the root cause of an interrupt can be determined by reading two register locations: the ICIP for an IRQ interrupt or the ICFP for an FIQ interrupt to determine the interrupting device. You then read the status register within that device to find the exact function requesting service.

When the ICCR[DIM] bit is zero, the Interrupt Mask Register is ignored during Idle mode, and all enabled interrupts cause the processor to exit from idle mode. Otherwise, only unmasked interrupts cause the processor to exit from idle mode. The reset state of ICCR[DIM] is zero.

Figure 4-2shows a block diagram of the Interrupt Controller.

Figure 4-2. Interrupt Controller Block Diagram

Interrupt Level

Register (ICLR)

ICCR[DIM]=0 & Idle mode=’1’

Interrupt Mask

Register (ICMR)

Interrupt Source

Bit

Interrupt Pending

Register (ICPR)

IRQ Interrupt

Pending Register

(ICIP)

FIQ Interrupt

Pending Register

(ICFP)

All Other Qualified

Interrupt Bits

23

23

 

FIQ

 

Interrupt

 

to

 

Processor

 

IRQ

 

Interrupt

 

to

 

Processor

4.2.2Interrupt Controller Register Definitions

The interrupt controller contains the following registers:

Interrupt Controller IRQ Pending register (ICIP)

Interrupt Controller FIQ Pending register (ICFP)

Interrupt Controller Pending register (ICPR)

Interrupt Controller Mask register (ICMR)

Interrupt Controller Level register (ICLR)

Interrupt Controller Control register (ICCR)

Intel® PXA255 Processor Developer’s Manual

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Intel PXA255 manual Interrupt Controller Register Definitions, Interrupt Controller Block Diagram