How to write GPIO interrupt handler in Linux device driver?

[TheInventor1993]

I am writing GPIO Device Driver for linux 3.14 on Beagleboard XM (RevB). I have done with simple ON/OFF LED blinking. But stuck at interrupt handler implementation. BB XM has GPIO_7 pin connected to user button. Following is code sample I have implemented. But it is not working. I am able to insert module using insmod. Interrupt is also registered in /proc/interrupts. But handler is not getting invoked.

Am I on right track?

#include <linux/gpio.h>
#include <linux/interrupt.h>

#define GPIO 7

int var;

static irqreturn_t irq_handler(int irq, void *dev_id)
{
  var++;
  printk("In the Interrupt handler, Count: %d\n", var);
  return IRQ_HANDLED;
}

static int __init hello_init(void)
{
  int errno, irq_line;
  if((errno = gpio_direction_input(GPIO)) !=0)
  {
    printk(KERN_INFO "Can't set GPIO direction, error %i\n", errno);
    gpio_free(GPIO);
    return -EINVAL;
  }
  irq_line = gpio_to_irq(GPIO);
  printk ("IRQ Line is %d \n",irq_line);

  errno = request_irq( irq_line, (irq_handler_t)irq_handler, IRQF_TRIGGER_FALLING, "Interrupt123", NULL );
  if(errno<0)
  {
    printk(KERN_INFO "Problem requesting IRQ, error %i\n", errno);
  }
  return 0;
}

static void __exit hello_exit(void)
{
  int irq_line;
  printk ("Unloading my module.\n");
  irq_line = gpio_to_irq(GPIO);
  free_irq(irq_line,NULL);
  printk("Hello Example Exit\n");
  return;
}

module_init(hello_init);
module_exit(hello_exit);

MODULE_AUTHOR("TheInventor");
MODULE_DESCRIPTION("Interrupt Module");
MODULE_LICENSE("GPL");

[Do Minh Quoc]

Hi,

Could you help me know where to store the linux/gpio.h file in beagleboard xM?

[santhos...@gmail.com]

It is working thank you

[Dave Chapman]

What does dmesg look like?

 

I would have made the variable var look like this

“static   int   var;”

 

Also, I would have added a proc to display the current value of var.

 

Finally, I would have added something this to hello_init():

printk(“Entered hello_init().\n”);

 

None of these things are strictly necessary, but that’s how I do it. . .

 

Regards,

 

Dave Chapman

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[santhos...@gmail.com]

I have used this driver on dragon 410c platform.

Not on Beagleboard.