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Date: Mon, 17 Jan 2011 19:28:11 +0100
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] Ext. Interrupt with POSIX skin from user - space
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To: Joerg Mohre <jmohre@domain.hid>
Cc: xenomai@xenomai.org

Joerg Mohre wrote:
> Hi all,
> 
> i am using a MPC52000 and try to handle external interrupts (IRQ1) with 
> linux kernel 2.6.32 and Xenomai 2.5.5.2.
> I use the POSIX skin functions to setup interrupt and wait for interrupt 
> in user-space.
> 
> First for testing, i wrote a kernel module to setup and handle the 
> interrupts.
> This worked well.
> 
> Now it tried to do the same from user-space with the posix functions.
> But unfortunately this wasn't successful.
> 
> I have to load the kernel module before i use my user-space application 
> (see code).
> Otherwise pthread_intr_control_np will fail with error -1 and errono = -19.
> 
> 
> static int mpc5200_intr_setup(void)
> {
>      int                     iret = 0;
>          int                                        err = 0;
>      pthread_attr_t          ThreadAttribute;
>          struct sched_param        sched_param;
>          unsigned char                 byPriority;
> 
>          unsigned int                i = 0;
> 
>          byPriority = 90;
>          sched_param.sched_priority = byPriority;
>          memset (&sched_param, 0, sizeof (sched_param));
> 
>      if ( (pRegsIntCtrl = (int_ctrl_regs*)ioremap( MBAR_VALUE + 
> MBAR_INT_CTRL, REMAP_SIZE )) == NULL) {
>                  printf("ioremap failed for MBAR_INT_CTRL\n");
>          return -1;
>          }
> 
>      //pRegsIntCtrl->irqctl =  0x00201401; //bit 10,21 => 1: IRQ1 rising 
> edge active; enable IRQ1
>      pRegsIntCtrl->irqctl =  0x00201001; //bit 10 => 1: IRQ1 rising edge 
> active; disbable IRQ1
> 
>          if (pthread_intr_attach_np (&irq_object, 65, 0)) {
>          printf("Interrupt source not found!\n");
>          return -1;
>      }
>          else {
>                  printf("Interrupt source found!\n");
>          }
> 
>          printf("pregs->irqctl = %08X\n",pRegsIntCtrl->irqctl);
> 
>          sleep(5);
> 
>          printf("%i\n", i+=1);
>      pthread_attr_init( &ThreadAttribute);
>          printf("%i\n", i+=1);
>      if (pthread_attr_setstacksize(&ThreadAttribute,0x80000)) {
>                  printf("Failed to set stack size\n");
>                  return -1;
>          }
>          printf("%i\n", i+=1);
>             if (pthread_create( &Thread, &ThreadAttribute, 
> cyclic_interrupt_receiver, NULL)) {
>                  printf("Failed to create thread\n");
>                  return -1;
>          }
>          printf("%i\n", i+=1);
>          if (pthread_setschedparam (Thread,SCHED_FIFO,&sched_param)) {
>                  printf("Failed to set scheduling parameter\n");
>                  return -1;
>          }
>          printf("%i\n", i+=1);
>          iret = pthread_intr_control_np (irq_object, PTHREAD_IENABLE);
>          if (iret)
>          {
>                  err = errno;
>                  printf("Failed to enable interrupt (%i, errno = %i)\n", 
> iret, err);
>                  return -1;
>          }
> 
>          printf("%i\n", i+=1);
>      return iret;
> }

The way you indented it, this code is unreadable.

> 
> If i enable IRQ1 with
> //pRegsIntCtrl->irqctl =  0x00201401; //bit 10,21 => 1: IRQ1 rising edge 
> active; enable IRQ1
> the CPU seams to be blocked.
> 
> I searched the internet but i couldn't find any help for handling 
> external interrupts with posix skin in user-space.
> 
> Is it necessary to request an irq with native functions from kernel module?
> 
> I would expect that all (request, enable setup type ....) is done by the 
> posix functions.

It should be done by the call to pthread_intr_attach_np. But do not take
my word for it, have a look at the code.

Anyway, handling interrupts in user-space is hard, handling them in an
RTDM driver is what we recommend.

-- 
                                                                Gilles.