CODEWITHSUNDEEP
linux-kernel
Anuj
Anuj

Reputation: 9632

writing basic keyboard interrupt handler, throws "Unknown key released"

I have written a rudimentary keyboard interrupt handler. It uses shared interrupts and is used to print to /var/log/messages which key got pressed. But i get the following error when i try to use arrow keys and rest of the keys work fine.

Aug 19 18:59:06 vim kernel: [ 112.485102] atkbd serio0: Unknown key released (translated set 2, code 0xe0 on isa0060/serio0). Aug 19 18:59:06 vim kernel: [ 112.485108] atkbd serio0: Use 'setkeycodes e060 ' to make it known.

Pasting the code.

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

/* This function services keyboard interrupts */
irq_handler_t irq_handler (int irq, void *dev_id, struct pt_regs *regs) {
  static unsigned char scancode;

  /*
    Read keyboard status
  */
  scancode = inb (0x60);

  if ((scancode == 0x01) || (scancode == 0x81))
    {
      printk ("You pressed Esc !\n");
    }
  }

  return (irq_handler_t) IRQ_HANDLED;
}

/* Initialize the module and Register the IRQ handler */
static int __init keybrd_int_register(void)
{
  int result;
  /* Request IRQ 1, the keyboard IRQ */    
  result = request_irq (1, (irq_handler_t) irq_handler, IRQF_SHARED, "keyboard_stats_irq", (void *)(irq_handler));

  if (result)
    printk(KERN_INFO "can't get shared interrupt for keyboard\n");

  return result;
}

/* Remove the interrupt handler */
static void __exit keybrd_int_unregister(void) {
  free_irq(1, (void *)(irq_handler)); /* i can't pass NULL, this is a shared interrupt handler! */
}

MODULE_LICENSE ("GPL");
module_init(keybrd_int_register);
module_exit(keybrd_int_unregister);

Can anyone please give me some clue on why this arrow keys stop working when i insert my module and start working whey i remove them?

I am running my code on a Virtual Machine.

Upvotes: 6

Views: 10982

Answers (1)

Anuj
Anuj

Reputation: 9632

The reason was due to some VM screw up. It works fine on base linux hosts. You can see the full implementation of code (naive) @ https://github.com/vigith/Linux-Device-Drivers/tree/master/keyboard

Upvotes: 4

Related Questions