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How to request and handle FIQ interrupt (DM3730+linux) ?

Konstantin
Intellectual 505 points

Hi!

I need to minimize latency for handling external interrupt (from GPIO4 bank), so i guess i need FIQ instead of IRQ. I've not found any good FAQ about FIQ in linux, so i have some questions:

1) Looks like i need to call claim_fiq function for registering handler. How should I fill fiq_handler for that? How linux would know that I need that FIQ for external interrupt from GPIO pin 111 ?

2) I've found a link: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00259791.pdf where said that I cannot use Linux API in FIQ handler. So can I use __raw_writel() at least, or only assembler? How can I call omap_start_dma() this way?

Thanks in advance.