interrupt handling by C code

Question

I am trying to disable interrupts through C code but stuck at request_irq(). One argument to request_irq() is flag and SA_INTERRUPT flag is now deprecated. Can anyone tell me alternative to SA_INTERRUPT?. I am using kernel version 3.8.

Any other alternative to request_irq() for disabling interrupts?

Welcome to Stack Overflow. Please read the About page soon. … … Hold on — where are you writing the code? In a kernel driver, or in a user application? If in a kernel driver, this should be tagged with the specific O/S; it might be Linux, but it isn't guaranteed. You'd also have to obey the rules of the kernel; you'll need to study other drivers to see what they do. If in an application, are you sure request_irq() is relevant at all? You'd normally be using sigaction() (or, at a pinch, signal()). — Jonathan Leffler
– Jonathan Leffler, Commented Mar 10, 2014 at 6:47

Alexey Polonsky · Accepted Answer · 2014-03-10 08:10:48Z

1

request_irq() does not "disable" an interrupt. It is called by a driver that wants to attach an interrupt service routine to an IRQ. The flag is IRQF_SHARED if the interrupt is shared or 0 otherwise.

Here is an example from a driver for Realtek 8169 PCIe network adapter: http://lxr.free-electrons.com/source/drivers/net/ethernet/realtek/r8169.c

 retval = request_irq(pdev->irq, rtl8169_interrupt,
      (tp->features & RTL_FEATURE_MSI) ? 0 : IRQF_SHARED,
      dev->name, dev);

In the example above, rtl8169_interrupt is the interrupt service routine (ISR) that will be invoked each time an IRQ is raised.

It is the job of the ISR to find out if the interrupt was indeed fired by the "owned" device (relevant for shared interrupts) then if the device indeed fired the interrupt, the ISR reads interrupt status then clears the interrupt.

answered Mar 10, 2014 at 8:10

Alexey Polonsky

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