IRQHandler in StarterWare

Hi Brad,

Which versoin of StarterWare you are referring to ? Could you please check StarterWare_02_00_00_06 exceptionHandler.S ? I could not see any operation you mentioned above. Only DSB instruction is present in IRQ Handler.

Regards,

Sujith.

This is from AM335X_StarterWare_02_00_00_06\examples\evmAM335x\isr_reloc\exceptionhandler_gcc.S and it uses DMB. You will also see it in exceptionhandler_ewarm.S   and exceptionhandler_cgttms470.asm.  You will also see it in FIQHandler in those files.  I sometimes look at things in multiple versions of assembler since I use RVDS4.1 which has a slightly different syntax than anything in StarterWare.

@*****************************************************************************

@* Function Definition of IRQ Handler
@******************************************************************************

@

@ The IRQ handler jumps to the ISR of highest priority pending IRQ.

@ This handler doesnot support nesting.

@

IRQHandler:

STMFD r13!, {r0-r3, r12, r14} @ Save context in IRQ stack

LDR r0, =ADDR_SIR_IRQ @ Get the Active IRQ

LDR r1, [r0]

AND r1, r1, #MASK_ACTIVE_IRQ @ Mask the Active IRQ number

LDR r0, =fnRAMVectors @ Load the base of the vector table

ADD r14, pc, #0 @ Save return address in LR

LDR pc, [r0, r1, lsl #2] @ Jump to the ISR

MOV r0, #NEWIRQAGR @ Acknowledge the current IRQ

LDR r1, =ADDR_CONTROL

STR r0, [r1]

DMB @ Barrier to complete the data write

LDMFD r13!, {r0-r3, r12, r14} @ Restore registers from IRQ stack

SUBS pc, r14, #0x4 @ Return to program before IRQ