i.MX28 Bare Metal Interrupt Handler

contra — Thu, 29 Aug 2013 14:34:10 GMT

Hi,

I'm creating a bare metal application as Linux or Win CE are way too complex for my application, I'm having a problem getting my interrupt handler to work. I have the Freescale IMX_OBDS project which has a vectors.s file, this contains the exception handlers for the core but does not demonstrate how to action an interrupt exception. I'd be grateful if anyone could provide a code example for this.

IMX_OBDS has exception vector definitions but doesn't use them:

startup_vectors:

ldr pc, reset_addr

ldr pc, undefined_addr

ldr pc, swi_addr

ldr pc, prefetch_addr

ldr pc, abort_addr

nop /* reserved vector */

ldr pc, irq_addr

ldr pc, fiq_addr

reset_addr: .word startup

undefined_addr: .word undefined_handler

swi_addr: .word swi_handler

prefetch_addr: .word prefetch_handler

abort_addr: .word abort_handler

irq_addr: .word irq_handler

fiq_addr: .word fiq_handler

/*!

* Exception Handlers

undefined_handler:

b undefined_handler

swi_handler:

b swi_handler

prefetch_handler:

b prefetch_handler

abort_handler:

b abort_handler

irq_handler:

b irq_handler

fiq_handler:

b fiq_handler

Re: i.MX28 Bare Metal Interrupt Handler

AnsonHuang — Tue, 03 Sep 2013 04:18:13 GMT

Hi, David

For interrupt using, I can provide some guides based on my understanding:

1. Need to copy these interrupt vectors to 0x00000000 or 0xffffffff address, for i.MX28, the interrupt vectors should be on high address which is 0xffffffff, if you enable mmu, this address means virtual address;

2. As this address is occupied by ROM, so I think you may need to enable MMU, then map other physical address to be vector address;

3. Enable interrupt controller and module's interrupt.

To debug it, you can use JTAG to set break point at 0xffff0018 which is irq vector, then when there is an irq pending, PC will stop at here, you can debug it step by step. Maybe you also can refer to uboot's interrupt mode which should be more simple compared to kernel.

i.MX Processorsのトピックi.MX28 Bare Metal Interrupt Handler

i.MX28 Bare Metal Interrupt Handler

Re: i.MX28 Bare Metal Interrupt Handler