[Xenomai] Problem Handling GPIO interrupts

* [Xenomai] Problem Handling GPIO interrupts
@ 2013-03-02  4:47 Jonathan Wallace
  2013-03-02  5:35 ` Gilles Chanteperdrix
  2013-03-02  5:41 ` Gilles Chanteperdrix
  0 siblings, 2 replies; 6+ messages in thread
From: Jonathan Wallace @ 2013-03-02  4:47 UTC (permalink / raw)
  To: xenomai

Hi all,

I'm trying to get a small variation of the usr_irq.c example working,
but rt_intr_wait keeps returning -38 without blocking and perror
prints success. If I don't let it print anything (so it will run
faster) it seg faults after about 4 or 5 seconds, calling rt_intr_wait
in an infinite loop during that time.

I'm also having an issue where if I run the program from an SSH
session, rt_task_create returns EPERM, but will return a success if I
run the program from the serial console. I can only assume there's
some difference in the shell processes at the kernel level, but if
there's a way to get around this, I would love to know too.

A little background about the IRQ, because I could have this all wrong
too... I exported a gpio pin and echoed "falling" into the edge file
in sysfs. This added an entry in /procs/interrupts "205:         42
  GPIO  gpiolib" The number 42, increments every time I press my
button to cause an physical interrupt on the pin so I know its at
least working up to that point. I used this number 205 as the argument
to rt_intr_create, but I'm not sure that was the right thing to do.

Here's the complete source code, its not complicated at all.

#include <sys/mman.h>
#include <errno.h>
#include <signal.h>
#include <native/task.h>
#include <native/intr.h>
#define IRQ_NUMBER 205          /* GPIOLIB interrupt */
#define TASK_PRIO  99           /* Highest RT priority */
#define TASK_MODE  0            /* No flags */
#define TASK_STKSZ 0            /* Stack size (use default one) */

RT_INTR intr_desc;
RT_TASK server_desc;

void irq_server(void *cookie)
{
        int err;
        for (;;) {
                /* Wait for the next interrupt */

                /* Always returns -38 instantly*/
                err = rt_intr_wait(&intr_desc, TM_INFINITE);

                if (err > 0) {
                        printf("Interrupt rcvd! %d events\n", err);
                } else switch (err) {
                case -ETIMEDOUT:
                        printf("Timed out waiting\n");
                        break;
                case -EINVAL:
                        printf("Inavlid argument\n");
                        break;
                case -EIDRM:
                        printf("Deleted object\n");
                        break;
                case -EINTR:
                        printf("unblocked\n");
                        break;
                case 0:
                        break;
                default:
                        printf("%d\n",err);
                        perror("irq_server");
                        break;
                }
        }
}

void catch_signal(int sig)
{
}

int main(int argc, char *argv[])
{
        signal(SIGTERM, catch_signal);
        signal(SIGINT, catch_signal);
        int err;

        mlockall(MCL_CURRENT | MCL_FUTURE);

        printf("Registering interrupt...\n");
        err = rt_intr_create(&intr_desc, "MyIrq", IRQ_NUMBER, 0);
        switch (err) {
        case -ENOMEM:
                printf("No mem!\n");
                goto fail1;
                break;
        case -EBUSY:
                printf("Busy!\n");
                goto fail1;
                break;
        default:
                break;
        }

        printf("Creating task...\n");
        err = rt_task_create(&server_desc,
                             "MyIrqServer",
                             TASK_STKSZ, TASK_PRIO, TASK_MODE);
        switch (err) {
        case -ENOMEM:
                printf("No mem!\n");
                goto fail2;
                break;
        case -EEXIST:
                printf("Name is already in use\n");
                goto fail2;
                break;
        case -EPERM:
                printf("EPERM, called from async context!\n");
                goto fail2;
                break;
        case 0: /* No error */
                printf("Starting task...\n");
                rt_task_start(&server_desc, &irq_server, NULL);
                break;
        }
        pause();
fail2:
        rt_task_delete(&server_desc);
fail1:
        rt_intr_delete(&intr_desc);
}

-Jon Wallace

^ permalink raw reply	[flat|nested] 6+ messages in thread