how to send signal from kernel space to user space

[webquinty]

Hello,

I have developed a kernel module to handle a irq.

#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <asm/io.h>
#include <linux/time.h>
#include <linux/ioport.h>

#define BASEPORT 0x378
#define LPT_INTERRUPT 7

unsigned int contador;

irq_handler_t handler(void)
{
        // do stuff
	outb_p(15, BASEPORT);
        printk(">>> PARALLEL PORT INT HANDLED %d\n", contador++);

	return 0;
}

int xinit_module(void)
{
int ret;
struct resource *lpt_res;

	contador = 0;
	// Request IRQ 7
        ret = request_irq(LPT_INTERRUPT, (irq_handler_t) handler, IRQF_DISABLED , "LEICIF", NULL);
	if (ret < 0)
	{
		printk("Error, can not request irq 7");	
		return (-1);
	}
	// Request access io region LPT
	lpt_res = request_region(BASEPORT, 3, "BASEPORT");
	if (lpt_res == NULL)
	{
		printk("Error en request_region.\n");
		return(-1);
	}

	// ENCIENDO UN LED
	outb_p(0x01, BASEPORT);

        //set port to interrupt mode; pins are output
        outb_p(0x00, BASEPORT + 2);
        outb_p(0x10, BASEPORT + 2);

        printk("wait for interrupt\n");

        // Here generate interrupt D0 signal connect to ACK signal
        outb(0, BASEPORT);
        outb(1, BASEPORT);

        printk("return code %d \n", ret);
        return 0;
}

void xcleanup_module(void)
{
        disable_irq(LPT_INTERRUPT);
        free_irq(LPT_INTERRUPT, NULL);
        printk("closed\n");
}

module_init(xinit_module);
module_exit(xcleanup_module);
MODULE_LICENSE("GPL");

This code works fine.

#insmod mydriver.ko
wait for interrupt
>>> PARALLEL PORT INT HANDLED 1
return code 0
#

And now, the big question, Could module driver send something (signal, etc) to user space program??
My idea is to execute a function in my user space program when interrupt handled.

Best regards.

[GNU-Fan]

how to send signal from kernel space to user space | KernelTrap

[webquinty]

Thanks a lot,

it is a very easy example to understand.