From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Thu, 14 Dec 2006 11:05:35 +0200
From: Heikki Lindholm <holindho@domain.hid>
MIME-Version: 1.0
Subject: Re: [Xenomai-help] Handling a interrupt from user space on PPC405
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To: Wolfgang Grandegger <wg@domain.hid>
Cc: xenomai@xenomai.org

Wolfgang Grandegger kirjoitti:
> Heikki Lindholm wrote:
> 
>> Niklaus Giger kirjoitti:
>>
>>> Hi
>>>
>>> I tried to use the FIT (Fixed Interrupt Timer) on my PPC405GPr board, 
>>> which uses 0x1010 as its interrupt vector in a user space 
>>> (vxworks-skin) application.
>>> <..>
>>>   RT_INTR FITnterrupt;
>>>   res = rt_intr_create(&FITnterrupt, 0, 0x1010, I_NOAUTOENA);
>>> <..>
>>> But I got -22 EINVAL as error.
>>> Could somebody please tell me, what is wrong with my example.
>>
>>
>> The 0x1010 is the HW interrupt vector, but the argument should be the 
>> interrupt _line_. Besides, last time I checked, the ppc405 FIT isn't 
>> even 'wired' in the kernel; actually, there's no space for the 
>> interrupt prologue code, which basically results that no handler is 
>> called when the FIT interrupt occurs.
> 
> 
> Yes, in head_4xx.c there is the following note:
> 
>   /* NOTE:
>    * FIT and WDT handlers are not implemented yet.
>    */
> 
> But the relevant code could be copied from the PIT interrupt.
> 
>   /* 0x1000 - Programmable Interval Timer (PIT) Exception */
>         START_EXCEPTION(0x1000, Decrementer)
>         NORMAL_EXCEPTION_PROLOG
>         lis     r0,TSR_PIS@h
>         mtspr   SPRN_TSR,r0             /* Clear the PIT exception */
>         addi    r3,r1,STACK_FRAME_OVERHEAD
>   #ifdef CONFIG_IPIPE
>         EXC_XFER_IPIPE(0x1000, __ipipe_grab_timer)
>   #else /* !CONFIG_IPIPE */
>         EXC_XFER_LITE(0x1000, timer_interrupt)
>   #endif /* CONFIG_IPIPE */
> 
> and modified accordingly.

But one should note that the decrementer vector is at 0x1000 and the FIT 
vector at 0x1010. The decrementer exception prologue is obviously bigger 
than 0x10 (16) bytes and thus needs to be moved elsewhere (and branched 
to from the decr vector.) It might be feasible to unite the handlers, 
though, by passing some variable to the C-language handler, telling 
which happened.

-- Heikki Lindholm