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

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Message-ID: <20190212100607.4etnqytsrtxtcqvc@pengutronix.de>
Date:   Tue, 12 Feb 2019 11:06:07 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Bartosz Golaszewski <bgolaszewski@...libre.com>
Cc:     Marc Zyngier <marc.zyngier@....com>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Linus Walleij <linus.walleij@...aro.org>,
        Thomas Gleixner <tglx@...utronix.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()

On Tue, Feb 12, 2019 at 10:19:20AM +0100, Bartosz Golaszewski wrote:
> 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.

I think the background of the question was: Why is there no support for
level sensitive irqs?

The userspace API has this limitation (also for no good reason I think).

Best regards
Uwe

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Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |