using general IRQs

[Ran Shalit]

On Tue, Aug 11, 2015 at 6:47 AM, Scott Wood <scottwood at freescale.com> wrote:
> On Tue, 2015-08-11 at 06:45 +0300, Ran Shalit wrote:
>> On Tue, Aug 11, 2015 at 5:29 AM, Scott Wood <scottwood at freescale.com> wrote:
>> > On Mon, 2015-08-10 at 13:40 +0300, Ran Shalit wrote:
>> > > On Mon, Aug 10, 2015 at 10:48 AM, Ran Shalit <ranshalit at gmail.com>
>> > > wrote:
>> > > > Hello,
>> > > >
>> > > > MPC8349 has general IRQ numbered 0-7,
>> > > > It is required to bind these IRQs with some routine , i.e. they are
>> > > > not used with any specific driver.
>> > > >
>> > > > - Should they be configured as gpios in device tree so that we can use
>> > > > the gpio as irq in linux ? Is there any example ?
>> > > > - After configuration, can the gpios be used in linux using the
>> > > > standard /sys/class/gpio ?
>> > > >
>> > > > Regards,
>> > > > Ran
>> >
>> > What do you mean by "general IRQ"?  Do you mean external IRQs?
>> >
>> > > I am trying to use only IRQ4, so I have tried to configure it as
>> > > following in device tree:
>> > >
>> > > device tree:
>> > >
>> > >   intc at 0{
>> > >  compatible = "intc";
>> > >  #address-cells = <1>;
>> > >  #size-cells = <0>;
>> > >  reg = <0 0x1000>;
>> > >  interrupts = <4 0x8>;
>> > >   };
>> > >
>> > > But I don't see IRQ4 listed in the interrupt list:
>> > > # cat /proc/interrupts
>> >
>> > /proc/interrupts shows virtual interrupts, which do not necessarily
>> > correspond to anything in the device tree.  In particular, virtual
>> > interrupts
>> > under 16 are reserved for ISA interrupts, and thus any mpic interrupts in
>> > that range will be remapped.
>> >
>> > Additionally, putting an interrupt in the device tree does not make it
>> > show
>> > up in /proc/interrupts.  Only interrupts for which a driver has
>> > registered a
>> > handler will show up in /proc/interrupts.
>> >
>> > -Scott
>> >
>> >
>> Hi Scott,
>>
>> I meant  external IRQ.
>> I am actually trying to use irq 4 interrupt.
>>
>> I've added the above in device tree, and in kernel code I do:
>> np = of_find_node_by_name(NULL,"hello");
>
> Why are you looking for a node named "hello" when your node is named "intc"?
I apologyze, this is the node I'm using

hello at 0{
 compatible = "hello";
  #address-cells = <1>;
  #size-cells = <0>;
  reg = <0 0x1000>;
  interrupts = <4 0x8>;
};

>
>>   if (np == NULL)
>>     {
>>     printk("Error node not found\n");
>>     }
>>   printk("Node np = 0x%0x\n",np);                     <-- Node np =
>> 0xdfffe2f0
>
> How could you possibly have gotten a non-NULL value for np, with the above
> code and node, unless there's something you're not showing?
You are right, The node is named hello in my device

>
>>   virq = irq_of_parse_and_map(np,0);
>>
>>   printk(" VIRQ: %d \n" , virq);                              <-- virq = 0
>> !!??
>
> virq = 0 means the lookup failed.  Either there was no interrupt in the node,
> or it couldn't be mapped for some reason.
>
>>   if (0 > (error=request_irq(virq, &hello_IRQHandler, IRQF_SHARED,
>> "hello", &value))) {
>>       printk(KERN_WARNING"hello_IRQHandler: Init: Unable to allocate
>> IRQ error = %d\n\n", error);
>>     return -1;
>>   <-- request_irq return -22 ....
>>   }
>>
>>
>>  But it fails in request_irq (it return -22).
>> Also, irq_of_parse_and_map(np,0) returns 0. I think it should have returned
>> 4.
>
> I already explained why it won't return 4 (see the part about virtual
> interrupts).

Thank you very much,
I now have success with the request_irq code.

Best Regards,
Ran