Re: request_irq return errno 38

[Michael Ellerman <michael@ellerman.id.au>]

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On Wed, 2009-02-11 at 14:13 +0530, Vijay Nikam wrote:
> Hello All,
> 
> I have mpc8313erdb evaluation board and currently I am writing GPIO
> driver. Actually it is just simple test driver.
> 
> I did the irq_request in the driver init function, as request_irq
> returns zero (0) if successful, otherwise -1 on error and errno
> indicates the error. But when I load or insert the module using insmod
> request_irq return with Return Value -38. I checked in errno.h file in
> asm-generic and 38 means ENOSYS - Function not implemented.
> Following is irq_request code:
> ----------------------
> ret = request_irq(74, interrupt_handler, SA_INTERRUPT | SA_SHIRQ ,
> "gpio", &mydev);
> if(ret)
>     printk(KERN_INFO "Error in request_irq, value return = %d \n", ret);
> ----------------------
> NOTE: 74 is the Interrupt ID Number for GPIO Interrupt. this
> information is from Processor User Manual.
> 
> Following is the handler:
> ---------------------
> static int interrupt_handler(int irqn, void *dev_id)
> {
>     printk(KERN_INFO "Enter in interrupt handler\n");
>     return IRQ_HANDLED;
> }
> --------------------
> 
> Usually request_irq return EBUSY, EINVAL but in my case it returns
> ENOSYS (errno 38). I tried to look information for this errno in
> interrupt context but could not able to find anything useful or
> understable. Could anyone please let me know why this specific errno
> 38 generated in request_irq ? ? ? and what are the possiblities for
> resolving this error ? ?  ?

You don't mention what kernel version you're using. But you might be
hitting the check in __setup_irq():

        if (desc->chip == &no_irq_chip)
                return -ENOSYS;


That would make sense because you're trying to map a raw irq number,
which doesn't work. You first need to call irq_create_mapping(), like:

int virq;
virq = irq_create_mapping(NULL, 74);
rc = request_irq(virq, ...);


cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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