On Fri, Sep 15, 2000 at 11:22:54AM +0900, Mukaila olundegun wrote:
>
> Actually, I have 4 devices on same board. Of course they all have thesame
> devname but have different deviceId with shared interrupt. The only way to
> identify which device generate interrupt is the deviceID. That means it will
> be very hard for "low_level_handler_installed_by_request_irq" to provide
> this requirement.
Something has to discover which device generated the interrupt. Generally
you would want the low level handler to do
handler:
look at board status registers to discover correct device
call dev_handler(device_name);
Linux does not figure this out for you: it calls every handler that shares the
interrupt and makes them figure it out. Here's the code in i386/kernel/irq.c
do {
status |= action->flags;
action->handler(irq, action->dev_id, regs);
action = action->next;
} while (action);
>
> Your further assistant will be helpful.
>
> Regards,
> Mukaila
> ----- Original Message -----
> From: Tomasz Motylewski <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Cc: Mukaila olundegun <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
> Sent: Friday, September 15, 2000 12:57 AM
> Subject: Re: [rtl] Linux request_irq() vs RTLinux rtl_request_irq()
>
>
> > On Thu, 14 Sep 2000 [EMAIL PROTECTED] wrote:
> >
> > > > service several interrupts. Quite common case when using some kind of
> > > > wrappers, etc. Having "device id" is a requirement. It was not present
> in
> > > > Linux initially, but soon people understood its usefulness.
> > >
> > >
> > > low_level_handler_installed_by_request_irq:
> > > general_handler(devname);
> > > return;
> > >
> > > Is that a problem?
> >
> > Yes. In low_level_handler_installed_by_request_irq I have no way to get
> > devname. We are talking about fully dynamic situations. Like I have two
> > identical cards, I want to use the same driver. At compile time I do not
> know
> > if I will install 1 or 5 interrupt handlers and for which devices. I also
> do
> > not know the names at compile time.
> >
> > Or should I use:
> >
> > switch(irq) {
> > case 5:
> > install low_level_handler_5;
> > break;
> > case 7:
> > install low_level_handler_7;
> > etc...
> > } ?
> >
> > Solution I would use now is to reproduce Linux 1.2 with an array of 16
> "irq
> > structures". I get IRQ number from some register as you have suggested,
> and
> > get all other data from my table indexed by IRQ.
> >
> > Best regards,
> > --
> > Tomek
> >
> >
--
---------------------------------------------------------
Victor Yodaiken
Finite State Machine Labs: The RTLinux Company.
www.fsmlabs.com www.rtlinux.com
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