linux-kernel - Re: [PATCH v2 2/5] irqchip: Add RZ/G2L IA55 Interrupt Controller driver

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Date:   Tue, 10 May 2022 10:11:25 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     "Lad, Prabhakar" <prabhakar.csengg@...il.com>
Cc:     Biju Das <biju.das.jz@...renesas.com>,
        Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <maz@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>
Subject: Re: [PATCH v2 2/5] irqchip: Add RZ/G2L IA55 Interrupt Controller driver

Hi Prabhakar,

On Mon, May 9, 2022 at 9:24 PM Lad, Prabhakar
<prabhakar.csengg@...il.com> wrote:
> On Mon, May 9, 2022 at 10:10 AM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> > On Mon, May 9, 2022 at 9:22 AM Biju Das <biju.das.jz@...renesas.com> wrote:
> > > > Subject: [PATCH v2 2/5] irqchip: Add RZ/G2L IA55 Interrupt Controller
> > > > driver
> > > >
> > > > Add a driver for the Renesas RZ/G2L Interrupt Controller.
> > > >
> > > > This supports external pins being used as interrupts. It supports one line
> > > > for NMI, 8 external pins and 32 GPIO pins (out of 123) to be used as IRQ
> > > > lines.
> > > >
> > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > > > --- /dev/null
> > > > +++ b/drivers/irqchip/irq-renesas-rzg2l.c
> >
> > > > +static void rzg2l_irqc_irq_disable(struct irq_data *d) {
> > > > +     unsigned int hw_irq = irqd_to_hwirq(d);
> > > > +
> > > > +     if (hw_irq >= IRQC_TINT_START && hw_irq <= IRQC_TINT_COUNT) {
> > > > +             struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> > > > +             u32 offset = hw_irq - IRQC_TINT_START;
> > > > +             u32 tssr_offset = TSSR_OFFSET(offset);
> > > > +             u8 tssr_index = TSSR_INDEX(offset);
> > > > +             u32 reg;
> > > > +
> > > > +             raw_spin_lock(&priv->lock);
> > > > +             reg = readl_relaxed(priv->base + TSSR(tssr_index));
> > > > +             reg &= ~(TSSEL_MASK << tssr_offset);
> > > > +             writel_relaxed(reg, priv->base + TSSR(tssr_index));
> > > > +             raw_spin_unlock(&priv->lock);
> > > > +     }
> > > > +     irq_chip_disable_parent(d);
> > > > +}
> >
> > > > +static int rzg2l_tint_set_edge(struct irq_data *d, unsigned int type) {
> > > > +     struct rzg2l_irqc_priv *priv = irq_data_to_priv(d);
> > > > +     unsigned int hwirq = irqd_to_hwirq(d);
> > > > +     u32 titseln = hwirq - IRQC_TINT_START;
> > > > +     u32 offset;
> > > > +     u8 sense;
> > > > +     u32 reg;
> > > > +
> > > > +     switch (type & IRQ_TYPE_SENSE_MASK) {
> > > > +     case IRQ_TYPE_EDGE_RISING:
> > > > +             sense = TITSR_TITSEL_EDGE_RISING;
> > > > +             break;
> > > > +
> > > > +     case IRQ_TYPE_EDGE_FALLING:
> > > > +             sense = TITSR_TITSEL_EDGE_FALLING;
> > > > +             break;
> > > > +
> > > > +     default:
> > > > +             return -EINVAL;
> > > > +     }
> > > > +
> > >
> > > > +     if (titseln < TITSR0_MAX_INT) {
> > > > +             offset = TITSR0;
> > > > +     } else {
> > > > +             titseln /= TITSEL_WIDTH;
> > > > +             offset  = TITSR1;
> > > > +     }
> > >
> > > as TITSR0 (0x24) and TITSR1(0x28) are contiguous address location
> > >
> > > May be like others, above declare it as
> > > u32 offset = TITSR0; ??
> > >
> > > and here
> > >  if ((titseln >= TITSR0_MAX_INT) {
> > >         titseln /= TITSEL_WIDTH;
> > >         offset  += 4;
> > >  }
> >
> > Why "titseln /= TITSEL_WIDTH"?
> > Shouldn't that be "titseln -= TITSR0_MAX_INT"?
>
> Ouch, that should be "titseln -= TITSR0_MAX_INT".
>
> > Do I need more coffee?
> >
> > Can't you define TITSR_{OFFSET,INDEX}() helper macros, like for
> > TSSR above?
> >
> you mean a macro to get the TITSELx offset?

Either a macro, or an open-coded calculation (if you need it in only
one place).

As TITSR0 and TITSR1 are stored contiguous, you can easily
derive offset/shift from irq index.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds