linux-kernel - Re: [PATCH v2 3/9] irq/irq_sim: provide irq_sim_fire

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Date:   Tue, 12 Feb 2019 10:19:20 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/9] irq/irq_sim: provide irq_sim_fire_type()

wt., 12 lut 2019 o 10:10 Marc Zyngier <marc.zyngier@....com> napisał(a):
>
> On 29/01/2019 08:44, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bgolaszewski@...libre.com>
> >
> > Provide a more specialized variant of irq_sim_fire() that allows to
> > specify the type of the fired interrupt. The type is stored in the
> > dummy irq context struct via the set_type callback.
> >
> > Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
> > ---
> >  include/linux/irq_sim.h |  9 ++++++++-
> >  kernel/irq/irq_sim.c    | 26 ++++++++++++++++++++++----
> >  2 files changed, 30 insertions(+), 5 deletions(-)
> >
> > diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
> > index b96c2f752320..647a6c8ffb31 100644
> > --- a/include/linux/irq_sim.h
> > +++ b/include/linux/irq_sim.h
> > @@ -23,6 +23,7 @@ struct irq_sim_work_ctx {
> >
> >  struct irq_sim_irq_ctx {
> >       bool                    enabled;
> > +     unsigned int            type;
> >  };
> >
> >  struct irq_sim {
> > @@ -37,7 +38,13 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs);
> >  int devm_irq_sim_init(struct device *dev, struct irq_sim *sim,
> >                     unsigned int num_irqs);
> >  void irq_sim_fini(struct irq_sim *sim);
> > -void irq_sim_fire(struct irq_sim *sim, unsigned int offset);
> > +void irq_sim_fire_type(struct irq_sim *sim,
> > +                    unsigned int offset, unsigned int type);
> >  int irq_sim_irqnum(struct irq_sim *sim, unsigned int offset);
> >
> > +static inline void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
> > +{
> > +     irq_sim_fire_type(sim, offset, IRQ_TYPE_DEFAULT);
> > +}
> > +
> >  #endif /* _LINUX_IRQ_SIM_H */
> > diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
> > index 2bcdbab1bc5a..e3160b5e59b8 100644
> > --- a/kernel/irq/irq_sim.c
> > +++ b/kernel/irq/irq_sim.c
> > @@ -25,6 +25,15 @@ static void irq_sim_irqunmask(struct irq_data *data)
> >       irq_ctx->enabled = true;
> >  }
> >
> > +static int irq_sim_set_type(struct irq_data *data, unsigned int type)
> > +{
> > +     struct irq_sim_irq_ctx *irq_ctx = irq_data_get_irq_chip_data(data);
> > +
> > +     irq_ctx->type = type;
> > +
> > +     return 0;
> > +}
> > +
> >  static void irq_sim_handle_irq(struct irq_work *work)
> >  {
> >       struct irq_sim_work_ctx *work_ctx;
> > @@ -107,6 +116,7 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
> >       sim->chip.name = "irq_sim";
> >       sim->chip.irq_mask = irq_sim_irqmask;
> >       sim->chip.irq_unmask = irq_sim_irqunmask;
> > +     sim->chip.irq_set_type = irq_sim_set_type;
> >
> >       sim->work_ctx.pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
> >       if (!sim->work_ctx.pending) {
> > @@ -192,21 +202,29 @@ irq_sim_get_ctx(struct irq_sim *sim, unsigned int offset)
> >  }
> >
> >  /**
> > - * irq_sim_fire - Enqueue an interrupt.
> > + * irq_sim_fire_type - Enqueue an interrupt.
> >   *
> >   * @sim:        The interrupt simulator object.
> >   * @offset:     Offset of the simulated interrupt which should be fired.
> > + * @type:    Type of the fired interrupt. Must be one of the following:
> > + *           IRQ_TYPE_EDGE_RISING, IRQ_TYPE_EDGE_FALLING,
> > + *           IRQ_TYPE_EDGE_BOTH, IRQ_TYPE_LEVEL_HIGH,
> > + *           IRQ_TYPE_LEVEL_LOW, IRQ_TYPE_DEFAULT
> >   */
> > -void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
> > +void irq_sim_fire_type(struct irq_sim *sim,
> > +                    unsigned int offset, unsigned int type)
> >  {
> >       struct irq_sim_irq_ctx *ctx = irq_sim_get_ctx(sim, offset);
> >
> > -     if (ctx->enabled) {
> > +     /* Only care about relevant flags. */
> > +     type &= IRQ_TYPE_SENSE_MASK;
> > +
> > +     if (ctx->enabled && (ctx->type & type)) {
>
> I wonder how realistic this is, given that you do not track the release
> of a level. In short, mo matter what the type is, you treat everything
> as edge.
>
> What is the point of this?
>

When userspace wants to monitor GPIO line interrupts, the GPIO
framework requests a threaded interrupt with IRQF_TRIGGER_FALLING,
IRQF_TRIGGER_RISING or both. The testing module tries to act like real
hardware and so if we pass only one of the *_TRIGGER_* flags, we want
the simulated interrupt of corresponding type to be fired.

Another solution - if you don't like this one -  would be to have more
specialized functions: irq_sim_fire_rising() and
irq_sim_fire_falling(). How about that?

Bart

> >               set_bit(offset, sim->work_ctx.pending);
> >               irq_work_queue(&sim->work_ctx.work);
> >       }
> >  }
> > -EXPORT_SYMBOL_GPL(irq_sim_fire);
> > +EXPORT_SYMBOL_GPL(irq_sim_fire_type);
> >
> >  /**
> >   * irq_sim_irqnum - Get the allocated number of a dummy interrupt.
> >
>
> Thanks,
>
>         M.
> --
> Jazz is not dead. It just smells funny...