linux-kernel - Re: [PATCH 04/19] irqchip: atmel-aic: replace magic numbers with named constant

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Message-ID: <20160104092904.19e68c69@bbrezillon>
Date:	Mon, 4 Jan 2016 09:29:04 +0100
From:	Boris Brezillon <boris.brezillon@...e-electrons.com>
To:	Milo Kim <milo.kim@...com>
Cc:	<tglx@...utronix.de>, <jason@...edaemon.net>,
	<marc.zyngier@....com>, <alexandre.belloni@...e-electrons.com>,
	<ludovic.desroches@...el.com>, <nicolas.ferre@...el.com>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 04/19] irqchip: atmel-aic: replace magic numbers with
 named constant

On Mon, 4 Jan 2016 13:28:28 +0900
Milo Kim <milo.kim@...com> wrote:

> One AIC IRQ chip can have 32 interrupt source.
> To enhance code readability, magic number is replaced with named constant,
> 'AIC_IRQS_PER_CHIP'.
> 
> aic_hw_init() initializes vector registers up to total number of
> AIC interrupts. This magic number is replaced with NR_AIC_IRQS.

Actually this is a limitation of the generic chip infrastructure
(the irq_chip_generic uses u32 fields to store its internal status, and
each irq is attributed a bit position, which explains the 32 irqs per
chip limit), so I think this macro should be defined in
include/linux/irq.h:

#define MAX_IRQS_PER_GENERIC_CHIP	32

> 
> Cc: Thomas Gleixner <tglx@...utronix.de>
> Cc: Jason Cooper <jason@...edaemon.net>
> Cc: Marc Zyngier <marc.zyngier@....com>
> Cc: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
> Cc: Boris BREZILLON <boris.brezillon@...e-electrons.com>
> Cc: Ludovic Desroches <ludovic.desroches@...el.com>
> Cc: Nicolas Ferre <nicolas.ferre@...el.com>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Milo Kim <milo.kim@...com>
> ---
>  drivers/irqchip/irq-atmel-aic-common.c | 11 ++++++-----
>  drivers/irqchip/irq-atmel-aic-common.h |  1 +
>  drivers/irqchip/irq-atmel-aic.c        |  2 +-
>  drivers/irqchip/irq-atmel-aic5.c       |  4 ++--
>  4 files changed, 10 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-atmel-aic-common.c b/drivers/irqchip/irq-atmel-aic-common.c
> index ef2c619..5effd52 100644
> --- a/drivers/irqchip/irq-atmel-aic-common.c
> +++ b/drivers/irqchip/irq-atmel-aic-common.c
> @@ -135,7 +135,7 @@ static void __init aic_common_ext_irq_of_init(struct irq_domain *domain)
>  		}
>  
>  		aic = gc->private;
> -		aic->ext_irqs |= (1 << (hwirq % 32));
> +		aic->ext_irqs |= (1 << (hwirq % AIC_IRQS_PER_CHIP));
>  	}
>  }
>  
> @@ -151,7 +151,7 @@ struct irq_domain *__init aic_common_of_init(struct device_node *node,
>  	int ret;
>  	int i;
>  
> -	nchips = DIV_ROUND_UP(nirqs, 32);
> +	nchips = DIV_ROUND_UP(nirqs, AIC_IRQS_PER_CHIP);
>  
>  	reg_base = of_iomap(node, 0);
>  	if (!reg_base)
> @@ -163,13 +163,14 @@ struct irq_domain *__init aic_common_of_init(struct device_node *node,
>  		goto err_iounmap;
>  	}
>  
> -	domain = irq_domain_add_linear(node, nchips * 32, ops, aic);
> +	domain = irq_domain_add_linear(node, nchips * AIC_IRQS_PER_CHIP, ops,
> +				       aic);
>  	if (!domain) {
>  		ret = -ENOMEM;
>  		goto err_free_aic;
>  	}
>  
> -	ret = irq_alloc_domain_generic_chips(domain, 32, 1, name,
> +	ret = irq_alloc_domain_generic_chips(domain, AIC_IRQS_PER_CHIP, 1, name,
>  					     handle_fasteoi_irq,
>  					     IRQ_NOREQUEST | IRQ_NOPROBE |
>  					     IRQ_NOAUTOEN, 0, 0);
> @@ -177,7 +178,7 @@ struct irq_domain *__init aic_common_of_init(struct device_node *node,
>  		goto err_domain_remove;
>  
>  	for (i = 0; i < nchips; i++) {
> -		gc = irq_get_domain_generic_chip(domain, i * 32);
> +		gc = irq_get_domain_generic_chip(domain, i * AIC_IRQS_PER_CHIP);
>  
>  		gc->reg_base = reg_base;
>  
> diff --git a/drivers/irqchip/irq-atmel-aic-common.h b/drivers/irqchip/irq-atmel-aic-common.h
> index c178557..4c0b471 100644
> --- a/drivers/irqchip/irq-atmel-aic-common.h
> +++ b/drivers/irqchip/irq-atmel-aic-common.h
> @@ -16,6 +16,7 @@
>  #ifndef __IRQ_ATMEL_AIC_COMMON_H
>  #define __IRQ_ATMEL_AIC_COMMON_H
>  
> +#define AIC_IRQS_PER_CHIP	32
>  
>  int aic_common_set_type(struct irq_data *d, unsigned type, unsigned *val);
>  
> diff --git a/drivers/irqchip/irq-atmel-aic.c b/drivers/irqchip/irq-atmel-aic.c
> index 6fcd680..c499949 100644
> --- a/drivers/irqchip/irq-atmel-aic.c
> +++ b/drivers/irqchip/irq-atmel-aic.c
> @@ -164,7 +164,7 @@ static void __init aic_hw_init(struct irq_domain *domain)
>  	irq_reg_writel(gc, 0xffffffff, AT91_AIC_IDCR);
>  	irq_reg_writel(gc, 0xffffffff, AT91_AIC_ICCR);
>  
> -	for (i = 0; i < 32; i++)
> +	for (i = 0; i < NR_AIC_IRQS; i++)
>  		irq_reg_writel(gc, i, AT91_AIC_SVR(i));
>  }
>  
> diff --git a/drivers/irqchip/irq-atmel-aic5.c b/drivers/irqchip/irq-atmel-aic5.c
> index 8b8f5e2..f5848c8 100644
> --- a/drivers/irqchip/irq-atmel-aic5.c
> +++ b/drivers/irqchip/irq-atmel-aic5.c
> @@ -306,9 +306,9 @@ static int __init aic5_of_init(struct device_node *node,
>  		return PTR_ERR(domain);
>  
>  	aic5_domain = domain;
> -	nchips = aic5_domain->revmap_size / 32;
> +	nchips = aic5_domain->revmap_size / AIC_IRQS_PER_CHIP;
>  	for (i = 0; i < nchips; i++) {
> -		gc = irq_get_domain_generic_chip(domain, i * 32);
> +		gc = irq_get_domain_generic_chip(domain, i * AIC_IRQS_PER_CHIP);
>  
>  		gc->chip_types[0].regs.eoi = AT91_AIC5_EOICR;
>  		gc->chip_types[0].chip.irq_mask = aic5_mask;



-- 
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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