kernel interrupt handler function type (compile error)

Question

I'm setting up a kernel interrupt handler with:

        irq_result = request_irq(53, gpeds_hdlr, 0, "gpeds_hdlr", NULL);

Then, I'm defining my interrupt handler with:

irq_handler_t gpeds_hdlr(int irq, void *dev_id)

Compiler complains with:

/home/pi/module/mod_gpio.c: In function ‘init_function’:
/home/pi/module/mod_gpio.c:86:31: error: passing argument 2 of ‘request_irq’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  irq_result = request_irq(53, gpeds_hdlr, 0, "gpeds_hdlr", NULL);
                               ^~~~~~~~~~
In file included from /home/pi/module/mod_gpio.c:1:
./include/linux/interrupt.h:157:45: note: expected ‘irq_handler_t’ {aka ‘enum irqreturn (*)(int,  void *)’} but argument is of type ‘irqreturn_t (* (*)(int,  void *))(int,  void *)’ {aka ‘enum irqreturn (* (*)(int,  void *))(int,  void *)’}
 request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
                               ~~~~~~~~~~~~~~^~~~~~~

If I define my interrupt handler this way, as suggested by some online resources:

irqreturn_t gpeds_hdlr(int irq, void *dev_id, struct pt_regs *regs) {

Then I get a very similar compile error:

/home/pi/module/mod_gpio.c: In function ‘init_function’:
/home/pi/module/mod_gpio.c:85:31: error: passing argument 2 of ‘request_irq’ from incompatible pointer type [-Werror=incompatible-pointer-types]
  irq_result = request_irq(53, gpeds_hdlr, 0, "gpeds_hdlr", NULL);
                               ^~~~~~~~~~
In file included from /home/pi/module/mod_gpio.c:1:
./include/linux/interrupt.h:157:45: note: expected ‘irq_handler_t’ {aka ‘enum irqreturn (*)(int,  void *)’} but argument is of type ‘irqreturn_t (*)(int,  void *, struct pt_regs *)’ {aka ‘enum irqreturn (*)(int,  void *, struct pt_regs *)’}
 request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
                               ~~~~~~~~~~~~~~^~~~~~~

How do I get past this?

Of note: linux/interrupt.h contains:

typedef irqreturn_t (*irq_handler_t)(int, void *);

and linux/irqreturn.h, included from linux/interrupt.h, contains:

typedef enum irqreturn irqreturn_t;

Thanks!

Answer 1

You should define your handler as following and pass handler to request_irq().

irqreturn_t handler(int irq, void *data){ }

The second error of yours is because you are saying that handler receives 3 parameters while it's supposed to receive only two.

The first error is because that the definitions are wrong you say handler is returning irq_handler_t while it's supposed to return irqreturn_t which is a typedef for an enum. while irq_handler_t is typedef for a function pointer.