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Subject: Re: [PATCH 3/3] irq/irq_sim: implement irq_sim_irq2offset()
To: Bartosz Golaszewski <brgl@bgdev.pl>,
        Thomas Gleixner <tglx@linutronix.de>,
        Jonathan Cameron <Jonathan.Cameron@huawei.com>,
        Lars-Peter Clausen <lars@metafoo.de>
Cc: linux-kernel@vger.kernel.org
References: <20171005124446.26265-1-brgl@bgdev.pl>
 <20171005124446.26265-4-brgl@bgdev.pl>
From: Marc Zyngier <marc.zyngier@arm.com>
Organization: ARM Ltd
Message-ID: <e1f7141c-8688-8b15-2cc2-24c1d0678713@arm.com>
Date: Wed, 18 Oct 2017 09:58:37 +0100
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On 05/10/17 13:44, Bartosz Golaszewski wrote:
> Add a routine allowing to retrieve the offset corresponding with an
> allocated interrupt number from an irq_sim object.
> 
> Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
> ---
>  include/linux/irq_sim.h |  1 +
>  kernel/irq/irq_sim.c    | 15 +++++++++++++++
>  2 files changed, 16 insertions(+)
> 
> diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
> index 246f593face8..e9768ca81e3e 100644
> --- a/include/linux/irq_sim.h
> +++ b/include/linux/irq_sim.h
> @@ -41,5 +41,6 @@ void irq_sim_fini(struct irq_sim *sim);
>  void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
>  int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
>  int irq_sim_baseirq(struct irq_sim *sim);
> +unsigned int irq_sim_irq2offset(struct irq_sim *sim, int irq);
>  
>  #endif /* _LINUX_IRQ_SIM_H */
> diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> index 1be10d0e295f..9a9a1bc8853c 100644
> --- a/kernel/irq/irq_sim.c
> +++ b/kernel/irq/irq_sim.c
> @@ -174,3 +174,18 @@ int irq_sim_baseirq(struct irq_sim *sim)
>  	return irq_sim_irqnum(sim, 0);
>  }
>  EXPORT_SYMBOL_GPL(irq_sim_baseirq);
> +
> +/**
> + * irq_sim_irq2offset - Get the offset of an allocated interrupt.
> + *
> + * @sim:        The interrupt simulator object.
> + * irq:         Allocated interrupt number.
> + *
> + * Perform a reverse lookup for the interrupt number and return its offset in
> + * the array allocated by sim_irq.
> + */
> +unsigned int irq_sim_irq2offset(struct irq_sim *sim, int irq)
> +{
> +	return irq - sim->irq_base;
> +}
> +EXPORT_SYMBOL_GPL(irq_sim_irq2offset);
> 

How is that useful in a random driver? The irq base and the offset are
things that should be internal to an irqchip. Maybe you could explain
the context you want to use this in.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...