[PATCH] au1x00 serial real interrupt

[PATCH] au1x00 serial real interrupt

[Rodolfo Giometti]

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Hello.

Here my patch to enable real interrupts management for the au1x00
CPUs.

Ciao,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
Linux Device Driver                             giometti@gnudd.com
Embedded Systems                     		giometti@linux.it
UNIX programming                     phone:     +39 349 2432127

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diff --git a/include/asm-mips/serial.h b/include/asm-mips/serial.h
index 7b23664..0197062 100644
--- a/include/asm-mips/serial.h
+++ b/include/asm-mips/serial.h
@@ -11,6 +11,14 @@
 
 #include <linux/config.h>
 
+#ifdef CONFIG_SOC_AU1X00
+/*
+ * We have to redefine "is_real_interrupt()" for Au1x00 CPUs...
+ */
+#undef is_real_interrupt
+#define is_real_interrupt(irq)	((irq) != ~0)
+#endif
+
 /*
  * This assumes you have a 1.8432 MHz clock for your UART.
  *

Re: [PATCH] au1x00 serial real interrupt

[Sergei Shtylyov]

Hello.

Rodolfo Giometti wrote:

> Here my patch to enable real interrupts management for the au1x00
> CPUs.

> ------------------------------------------------------------------------
> 
> diff --git a/include/asm-mips/serial.h b/include/asm-mips/serial.h
> index 7b23664..0197062 100644
> --- a/include/asm-mips/serial.h
> +++ b/include/asm-mips/serial.h
> @@ -11,6 +11,14 @@
>  
>  #include <linux/config.h>
>  
> +#ifdef CONFIG_SOC_AU1X00
> +/*
> + * We have to redefine "is_real_interrupt()" for Au1x00 CPUs...
> + */
> +#undef is_real_interrupt
> +#define is_real_interrupt(irq)	((irq) != ~0)
> +#endif
> +
>  /*
>   * This assumes you have a 1.8432 MHz clock for your UART.
>   *

    Ralf, how about this patch? Can it be applied, at least 3 months after 
posting? Alchemy UART0 uses IRQ0 and 0 is treated as "no IRQ" by 
drivers/serial/8250.c which says the macro should be redefined in 
<asm/serial.h> if needed.

WBR, Sergei

Re: [PATCH] au1x00 serial real interrupt

[Sergei Shtylyov]

Hello.

Sergei Shtylyov wrote:

>> ------------------------------------------------------------------------
>>
>> diff --git a/include/asm-mips/serial.h b/include/asm-mips/serial.h
>> index 7b23664..0197062 100644
>> --- a/include/asm-mips/serial.h
>> +++ b/include/asm-mips/serial.h
>> @@ -11,6 +11,14 @@
>>  
>>  #include <linux/config.h>
>>  
>> +#ifdef CONFIG_SOC_AU1X00
>> +/*
>> + * We have to redefine "is_real_interrupt()" for Au1x00 CPUs...
>> + */
>> +#undef is_real_interrupt
>> +#define is_real_interrupt(irq)    ((irq) != ~0)
>> +#endif
>> +
>>  /*
>>   * This assumes you have a 1.8432 MHz clock for your UART.
>>   *

>    Ralf, how about this patch? Can it be applied, at least 3 months 
> after posting? Alchemy UART0 uses IRQ0 and 0 is treated as "no IRQ" by 
> drivers/serial/8250.c which says the macro should be redefined in 
> <asm/serial.h> if needed.

    If the values other than 0 need to be filtered out, to be precise...

    Well, after looking at drivers/serial/8250.c a bit more, I think this may 
be even more simlified since that driver seems to treat the negative values as 
completely invalid anyway. IOW, we can just:

#define is_real_interrupt(irq)	1

    Russel, what do you think?

WBR, Sergei

Re: [PATCH] au1x00 serial real interrupt

[Russell King]

On Sat, Sep 09, 2006 at 08:34:28PM +0400, Sergei Shtylyov wrote:
>    Well, after looking at drivers/serial/8250.c a bit more, I think this 
>    may be even more simlified since that driver seems to treat the negative 
> values as completely invalid anyway. IOW, we can just:
> 
> #define is_real_interrupt(irq)	1
> 
>    Russel, what do you think?

That's Russell 8)

Well, if you need IRQ0 to be real then redefining is_real_interrupt()
is the correct way forward.

However, Linus' policy is that IRQ0 shall be invalid at least on PCI
systems, and architectures _should_ remap their real IRQ0 to some other
number.  Personally I don't like this.  Hence why I prefer to give people
the option.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:  2.6 Serial core

Re: [PATCH] au1x00 serial real interrupt

[Sergei Shtylyov]

Hello.

Russell King wrote:

>>   Well, after looking at drivers/serial/8250.c a bit more, I think this 
>>   may be even more simlified since that driver seems to treat the negative 
>>values as completely invalid anyway. IOW, we can just:

>>#define is_real_interrupt(irq)	1

>>   Russel, what do you think?

> That's Russell 8)

    I'm sorry. :-)

> Well, if you need IRQ0 to be real then redefining is_real_interrupt()
> is the correct way forward.

> However, Linus' policy is that IRQ0 shall be invalid at least on PCI
> systems, and architectures _should_ remap their real IRQ0 to some other
> number.

   Hm, given that NO_IRQ is #defined as -1 (when it's defined at all)...

>  Personally I don't like this.

    Hm, me neither but I can undestand the reasoning. 0 is the usual default
value of the PCI interrupt line register, meaning interrupt is unassigned.

 > Hence why I prefer to give people the option.

    Thanks for the explanation.
    Would be better probably to have that #define in 8250.c going after 
#include <asm/serial.h> but as this seems the first and only case of the 
override needed, it's good enough this way. :-)
    As for the PCI UARTs possibly plugged into Alchemy board, I really don't 
know... This macro has no provision to check for the UART type. So, skipping 
its invocation in 8250.c for UPIO_AU case might be a better (though not 
cleaner) solution...

WBR, Sergei

Re: [PATCH] au1x00 serial real interrupt

[Ralf Baechle]

On Sat, Sep 09, 2006 at 05:39:07PM +0100, Russell King wrote:

> Well, if you need IRQ0 to be real then redefining is_real_interrupt()
> is the correct way forward.
> 
> However, Linus' policy is that IRQ0 shall be invalid at least on PCI
> systems, and architectures _should_ remap their real IRQ0 to some other
> number.  Personally I don't like this.  Hence why I prefer to give people
> the option.

I have no strong opinion either.  In some cases not having interrupt 0
available sucks because Linux will have to use a different interrupt
numbering than system documentation ...

  Ralf

Re: [PATCH] au1x00 serial real interrupt

[Sergei Shtylyov]

Hello.

Sergei Shtylyov wrote:

>>> diff --git a/include/asm-mips/serial.h b/include/asm-mips/serial.h
>>> index 7b23664..0197062 100644
>>> --- a/include/asm-mips/serial.h
>>> +++ b/include/asm-mips/serial.h
>>> @@ -11,6 +11,14 @@
>>>  
>>>  #include <linux/config.h>
>>>  
>>> +#ifdef CONFIG_SOC_AU1X00
>>> +/*
>>> + * We have to redefine "is_real_interrupt()" for Au1x00 CPUs...
>>> + */
>>> +#undef is_real_interrupt
>>> +#define is_real_interrupt(irq)    ((irq) != ~0)
>>> +#endif
>>> +
>>>  /*
>>>   * This assumes you have a 1.8432 MHz clock for your UART.
>>>   *

>    Well, after looking at drivers/serial/8250.c a bit more, I think this 
> may be even more simlified since that driver seems to treat the negative 
> values as completely invalid anyway. IOW, we can just:

> #define is_real_interrupt(irq)    1

    Rodolfo, can you do this (possibly adding more elaborate comment about 
UART0 using IRQ0)?

WBR, Sergei