On Sat, Oct 20, 2012 at 9:38 AM, anish kumar <anish198519851985@xxxxxxxxx> wrote:
And this is done by this way:On Fri, 2012-10-19 at 10:34 +0530, Arun KS wrote:
> Hi Anish,
>
> On Mon, May 28, 2012 at 9:16 AM, anish singh
> <anish198519851985@xxxxxxxxx> wrote:
> On Mon, May 28, 2012 at 2:57 AM, richard -rw- weinberger
> <richard.weinberger@xxxxxxxxx> wrote:
> > On Sun, May 27, 2012 at 2:02 AM, Mark Farnell
> <mark.farnell@xxxxxxxxx> wrote:
> >> In the kernel, how can I find out the interrupt vector
> number of a
> >> given IRQ (for example, IRQ7)?
> >>
> >> Within the kernel module, I would like to manually set the
> IRQ using
> >> the assembly code:
> >>
> >> asm("int $<irq vector>");
> >>
> >> and let the IRQ handler installed by a different module
> catch that interrupt.
> >>
> >> Is this possible?
> >
> > No really because not all IRQ have an interrupt line to the
> CPU.
> > Linux can multiplex and emulate them. Think of GPIO drivers
> with
> > interrupt support.
>
> Can you please describe this in detail?It would really help a
> lot of
> people like me.Does multiplex mean that all numbers starting
> from
> 0,1,2,3,...... TOTAL-interrupt will have interrupt lines
> associated with it
> eventhough all interrupt numbers are not linear?
>
> GPIOs are grouped as banks. Let’s say 32 gpios are in a bank.
> There will be only single interrupt line to interrupt controller for a
> bank.
>
>
> Consider that you have configured gpio1 and gpio16 as interrupts.
> Even if interrupt happens on gpio 1 or gpio 16, the same interrupt
> line will be triggered to
>
> Interrupt controller.
>
>
> Now the gpio driver has to figure out reading the Interrupt status
>
> Register of GPIO to find which interrupt (gpio1 or gpio16) has really
> fired.
Suppose we have a chip(mfd-multi-funcion-driver) driver which is
connected to processor using a gpio - this gpio line acts as interrupt
line from the processor
Interrupt lines are to the interrupt controllor(IC) and only two interrupts lines fom IC(irq and fiq in case of ARM) goes to processor.
++++++++++++ ++++++++++
+ Processor+ + Chip +---->USB interrupt handler
+ +gpio--------->+ MFD +---->dock interrupt handler
++++++++++++ + +---->UART interrupt handler
++++++++++---->Factory cable interrupt handler
So the code will be as follows:
handler_function()
{
/* find out which interrupt is triggered */
/* it can be usb,dock,uart or factory cable */
ret_irq = read_mfd_register();
/*
* ok we found out the interrupt line, get a corresponding
* software linux irq number by calling
* irq_domain_add_linear
* irq_create_mapping
* you would have made this calls in the probe probably
*/
handle_nested_irq(ret_irq);
}
handle_nested_irq inturn will call all the irq_handlers in the system
for your UART,usb and dock driver.
mfd_driver()
{
request_irq(gpio_to_irq(gpio), handler_function);
}
Yes. This is another example of interrupt multipexing...
Here you have two levels of multiplexing. One for the mfd devices functions and other for gpio.
Thanks,
Arun
Here you have two levels of multiplexing. One for the mfd devices functions and other for gpio.
Thanks,
Arun
Hope I have not missed anything.
>
> So in this case a single interrupt line is multiplex for 32 gpio
> interrupts.
>
>
> HTH.
>
> Thanks,
> Arun
>
> > Anyway, why to you think you need to trigger the raw IRQ
> manually?
> > This sounds really odd...
> >
> >
> > --
> > Thanks,
> > //richard
> >
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