AT91: Convert to fasteoi IRQ handler, and remove ARM irq_finish

[torbenh]

On Wed, Apr 27, 2011 at 03:09:02PM +0200, Andrew Victor wrote:
> The AT91's AIC interrupt controller will internally mask the current
> (and lower-priority) interrupts until software acknowledges that the
> interrupt was handled by writing to the AIC_EOICR register.
> 
> This matches the "fasteoi" IRQ flow-handler, so convert the AT91 to use
> handle_fasteoi_irq rather than handle_level_irq.
> 
> This also allows the irq_finish() call to be removed from the low-level
> ARM IRQ handler.
> 
> 
> Signed-off-by: Andrew Victor <linux at maxim.org.za>
> 
> 
> 
> diff -urN -x CVS linux-2.6.38/arch/arm/kernel/irq.c linux-2.6/arch/arm/kernel/irq.c
> --- linux-2.6.38/arch/arm/kernel/irq.c	2011-04-27 12:28:25.609111745 +0200
> +++ linux-2.6/arch/arm/kernel/irq.c	2011-04-27 14:20:32.784167994 +0200
> @@ -42,13 +42,6 @@
>  #include <asm/mach/irq.h>
>  #include <asm/mach/time.h>
>  
> -/*
> - * No architecture-specific irq_finish function defined in arm/arch/irqs.h.
> - */
> -#ifndef irq_finish
> -#define irq_finish(irq) do { } while (0)
> -#endif
> -
>  unsigned long irq_err_count;
>  
>  int show_interrupts(struct seq_file *p, void *v)
> @@ -135,9 +128,6 @@
>  		generic_handle_irq(irq);
>  	}
>  
> -	/* AT91 specific workaround */
> -	irq_finish(irq);
> -
>  	irq_exit();
>  	set_irq_regs(old_regs);
>  }
> diff -urN -x CVS linux-2.6.38/arch/arm/mach-at91/gpio.c linux-2.6/arch/arm/mach-at91/gpio.c
> --- linux-2.6.38/arch/arm/mach-at91/gpio.c	2011-04-27 12:28:26.157080664 +0200
> +++ linux-2.6/arch/arm/mach-at91/gpio.c	2011-04-27 14:45:42.672364605 +0200
> @@ -392,8 +392,6 @@
>  	at91_gpio = get_irq_chip_data(irq);
>  	pio = at91_gpio->regbase;
>  
> -	/* temporarily mask (level sensitive) parent IRQ */
> -	desc->irq_data.chip->irq_ack(&desc->irq_data);
>  	for (;;) {
>  		/* Reading ISR acks pending (edge triggered) GPIO interrupts.
>  		 * When there none are pending, we're finished unless we need
> @@ -429,8 +427,8 @@
>  			isr >>= 1;
>  		}
>  	}
> -	desc->irq_data.chip->irq_unmask(&desc->irq_data);
> -	/* now it may re-trigger */
> +	/* acknowledge interrupt - now it may re-trigger */
> +	desc->irq_data.chip->irq_eoi(&desc->irq_data);
>  }

why does this handler mess with the parent irq chip ?
this looks pretty wrong to me.

>  
>  /*--------------------------------------------------------------------------*/
> diff -urN -x CVS linux-2.6.38/arch/arm/mach-at91/include/mach/irqs.h linux-2.6/arch/arm/mach-at91/include/mach/irqs.h
> --- linux-2.6.38/arch/arm/mach-at91/include/mach/irqs.h	2009-06-10 05:05:27.000000000 +0200
> +++ linux-2.6/arch/arm/mach-at91/include/mach/irqs.h	2011-04-27 14:20:48.471334804 +0200
> @@ -28,13 +28,6 @@
>  
>  
>  /*
> - * Acknowledge interrupt with AIC after interrupt has been handled.
> - *   (by kernel/irq.c)
> - */
> -#define irq_finish(irq) do { at91_sys_write(AT91_AIC_EOICR, 0); } while (0)
> -
> -
> -/*
>   * IRQ interrupt symbols are the AT91xxx_ID_* symbols
>   * for IRQs handled directly through the AIC, or else the AT91_PIN_*
>   * symbols in gpio.h for ones handled indirectly as GPIOs.
> diff -urN -x CVS linux-2.6.38/arch/arm/mach-at91/irq.c linux-2.6/arch/arm/mach-at91/irq.c
> --- linux-2.6.38/arch/arm/mach-at91/irq.c	2011-04-27 12:28:26.197078404 +0200
> +++ linux-2.6/arch/arm/mach-at91/irq.c	2011-04-27 14:23:29.817625842 +0200
> @@ -46,6 +46,12 @@
>  	at91_sys_write(AT91_AIC_IECR, 1 << d->irq);
>  }
>  
> +static void at91_aic_eoi(struct irq_data *d)
> +{
> +	/* Acknowledge with AIC after interrupt has been handled */
> +	at91_sys_write(AT91_AIC_EOICR, 0);	
> +}
> +
>  unsigned int at91_extern_irq;
>  
>  #define is_extern_irq(irq) ((1 << (irq)) & at91_extern_irq)
> @@ -122,6 +128,7 @@
>  	.irq_ack	= at91_aic_mask_irq,

you should probably remove the ack. its just confusing.

>  	.irq_mask	= at91_aic_mask_irq,
>  	.irq_unmask	= at91_aic_unmask_irq,
> +	.irq_eoi	= at91_aic_eoi,
>  	.irq_set_type	= at91_aic_set_type,
>  	.irq_set_wake	= at91_aic_set_wake,
>  };
> @@ -144,7 +151,7 @@
>  		at91_sys_write(AT91_AIC_SMR(i), AT91_AIC_SRCTYPE_LOW | priority[i]);
>  
>  		set_irq_chip(i, &at91_aic_chip);
> -		set_irq_handler(i, handle_level_irq);
> +		set_irq_handler(i, handle_fasteoi_irq);
>  		set_irq_flags(i, IRQF_VALID | IRQF_PROBE);
>  
>  		/* Perform 8 End Of Interrupt Command to make sure AIC will not Lock out nIRQ */
> 
> 
> 
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-- 
torben Hohn