linux-kernel - Re: [PATCH v4 2/2] irq/irq

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Date:   Tue, 12 May 2020 16:37:14 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>
Subject: Re: [PATCH v4 2/2] irq/irq_sim: simplify the API

Bartosz,

On 2020-04-30 15:30, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> 
> The interrupt simulator API exposes a lot of custom data structures and
> functions and doesn't reuse the interfaces already exposed by the irq
> subsystem. This patch tries to address it.
> 
> We hide all the simulator-related data structures from users and 
> instead
> rely on the well-known irq domain. When creating the interrupt 
> simulator
> the user receives a pointer to a newly created irq_domain and can use 
> it
> to create mappings for simulated interrupts.
> 
> It is also possible to pass a handle to fwnode when creating the 
> simulator
> domain and retrieve it using irq_find_matching_fwnode().
> 
> The irq_sim_fire() function now only takes the virtual interrupt number
> as argument - there's no need anymore to pass it any data structure 
> linked
> to the simulator.
> 
> We modify the two modules that use the simulator at the same time as
> adding these changes in order to reduce the intermediate bloat that 
> would
> result when trying to migrate the drivers in separate patches.
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> Acked-by: Jonathan Cameron <Jonathan.Cameron@...wei.com> #for IIO
> ---
>  drivers/gpio/gpio-mockup.c          |  47 ++++--
>  drivers/iio/dummy/iio_dummy_evgen.c |  32 ++--
>  include/linux/irq_sim.h             |  34 ++---
>  kernel/irq/Kconfig                  |   1 +
>  kernel/irq/irq_sim.c                | 225 +++++++++++++++++-----------
>  5 files changed, 202 insertions(+), 137 deletions(-)

[...]

>  /**
>   * irq_sim_fire - Enqueue an interrupt.
>   *
> - * @sim:        The interrupt simulator object.
> - * @offset:     Offset of the simulated interrupt which should be 
> fired.
> + * @virq:       Virtual interrupt number to fire. It must be 
> associated with
> + *              an existing interrupt simulator.
>   */
> -void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
> +void irq_sim_fire(int virq)
>  {
> -	if (sim->irqs[offset].enabled) {
> -		set_bit(offset, sim->work_ctx.pending);
> -		irq_work_queue(&sim->work_ctx.work);
> +	struct irq_sim_irq_ctx *irq_ctx;
> +	struct irq_data *irqd;
> +
> +	irqd = irq_get_irq_data(virq);
> +	if (!irqd) {
> +		pr_warn_ratelimited("%s: invalid irq number\n", __func__);
> +		return;
>  	}
> -}
> -EXPORT_SYMBOL_GPL(irq_sim_fire);
> 
> -/**
> - * irq_sim_irqnum - Get the allocated number of a dummy interrupt.
> - *
> - * @sim:        The interrupt simulator object.
> - * @offset:     Offset of the simulated interrupt for which to 
> retrieve
> - *              the number.
> - */
> -int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset)
> -{
> -	return sim->irqs[offset].irqnum;
> +	irq_ctx = irq_data_get_irq_chip_data(irqd);
> +
> +	if (irq_ctx->enabled) {
> +		set_bit(irqd_to_hwirq(irqd), irq_ctx->work_ctx->pending);
> +		irq_work_queue(&irq_ctx->work_ctx->work);
> +	}
>  }
> -EXPORT_SYMBOL_GPL(irq_sim_irqnum);
> +EXPORT_SYMBOL_GPL(irq_sim_fire);

Rather than using an ad-hoc API to queue an interrupt, why don't you
actually implement the interface that already exists for this at
the irqchip level (irq_set_irqchip_state, which allows the pending
state to be set)?

Thanks,

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