Keyboard interrupt - request_irq()

Keyboard interrupt - request_irq()

[Pioz]

Hi all,
  I have a problem.
I want handle the keyboard interrupt and for this purpose I have write
this module (I have kernel 2.6.23):


#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/interrupt.h>

[...]

irqreturn_t
irq_myhandler (int irqn, void *dev)
{
        printk (KERN_INFO "Key pressed...\n");
        return IRQ_HANDLED;
}

int
init_module ()
{
        int res;
        printk (KERN_INFO "Hello World!\n");
        free_irq (1, NULL);
        res = request_irq (1, irq_myhandler, IRQF_SHARED, "bao", dev_id);
        printk (KERN_INFO "res: %d\n", res);
        return 0;
}

void
cleanup_module ()
{
        free_irq (1, NULL);
        printk (KERN_INFO "Goodbye World!\n");
}


The return value of request_irq() function is -EBUSY. Why? Is the
default handler? How can I do to change handler with my function?
Thanks...

Re: Keyboard interrupt - request_irq()

[Robert Hancock]

Pioz wrote:
> Hi all,
>   I have a problem.
> I want handle the keyboard interrupt and for this purpose I have write
> this module (I have kernel 2.6.23):
> 
> 
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/interrupt.h>
> 
> [...]
> 
> irqreturn_t
> irq_myhandler (int irqn, void *dev)
> {
>         printk (KERN_INFO "Key pressed...\n");
>         return IRQ_HANDLED;
> }
> 
> int
> init_module ()
> {
>         int res;
>         printk (KERN_INFO "Hello World!\n");
>         free_irq (1, NULL);
>         res = request_irq (1, irq_myhandler, IRQF_SHARED, "bao", dev_id);
>         printk (KERN_INFO "res: %d\n", res);
>         return 0;
> }
> 
> void
> cleanup_module ()
> {
>         free_irq (1, NULL);
>         printk (KERN_INFO "Goodbye World!\n");
> }
> 
> 
> The return value of request_irq() function is -EBUSY. Why? Is the
> default handler? How can I do to change handler with my function?
> Thanks...

Normally one doesn't register multiple interrupt handlers for the same 
device. For a PCI level-triggered interrupt one can do it (for the case 
where multiple devices share the IRQ), but the PC keyboard interrupt is 
edge-triggered and isn't sharable.

Re: Keyboard interrupt - request_irq()

[Jiri Kosina]

On Thu, 21 Feb 2008, Pioz wrote:

>   I have a problem.
> I want handle the keyboard interrupt and for this purpose I have write
> this module (I have kernel 2.6.23):
[ ... ]
>         res = request_irq (1, irq_myhandler, IRQF_SHARED, "bao", dev_id);
[ ... ]
> The return value of request_irq() function is -EBUSY. Why? Is the
> default handler? How can I do to change handler with my function?
> Thanks...

The check in setup_irq() very probably triggers for you:

               /*
                 * Can't share interrupts unless both agree to and are
                 * the same type (level, edge, polarity). So both flag
                 * fields must have IRQF_SHARED set and the bits which
                 * set the trigger type must match.
                 */
                if (!((old->flags & new->flags) & IRQF_SHARED) ||
                    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
                        old_name = old->name;
                        goto mismatch;
                }

-- 
Jiri Kosina
SUSE Labs