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From:   "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
Date:   Fri, 13 May 2022 19:13:29 +0100
Message-ID: <CA+V-a8uXakF45TLvpsfeAY_EZKDGHr-wfgqLR_LTz1ZAo8FYmg@mail.gmail.com>
Subject: Re: [PATCH v3 5/5] pinctrl: renesas: pinctrl-rzg2l: Add IRQ domain to
 handle GPIO interrupt
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        Linus Walleij <linus.walleij@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Marc Zyngier <maz@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        Phil Edworthy <phil.edworthy@renesas.com>,
        Biju Das <biju.das.jz@bp.renesas.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Geert

On Fri, May 13, 2022 at 3:29 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Fri, May 13, 2022 at 3:56 PM Lad, Prabhakar
> <prabhakar.csengg@gmail.com> wrote:
> > On Fri, May 13, 2022 at 7:53 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > On Thu, May 12, 2022 at 7:36 PM Lad, Prabhakar
> > > <prabhakar.csengg@gmail.com> wrote:
> > > > On Thu, May 12, 2022 at 8:39 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > > On Wed, May 11, 2022 at 8:32 PM Lad Prabhakar
> > > > > <prabhakar.mahadev-lad.rj@bp.renesas.com> wrote:
> > > > > > Add IRQ domian to RZ/G2L pinctrl driver to handle GPIO interrupt.
> > > > > > GPIO0-GPIO122 pins can be used as IRQ lines but only 32 pins can be
> > > > > > used as IRQ lines at given time. Selection of pins as IRQ lines
> > > > > > is handled by IA55 (which is the IRQC block) which sits in between the
> > > > > > GPIO and GIC.
> > > > > >
> > > > > > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > > > >
> > > > > Thanks for your patch!
> > > > >
> > > > > > --- a/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > > > > +++ b/drivers/pinctrl/renesas/pinctrl-rzg2l.c
> > > > >
> > > > > >  static int rzg2l_gpio_register(struct rzg2l_pinctrl *pctrl)
> > > > > >  {
> > > > > >         struct device_node *np = pctrl->dev->of_node;
> > > > > >         struct gpio_chip *chip = &pctrl->gpio_chip;
> > > > > >         const char *name = dev_name(pctrl->dev);
> > > > > > +       struct irq_domain *parent_domain;
> > > > > >         struct of_phandle_args of_args;
> > > > > > +       struct device_node *parent_np;
> > > > > > +       struct gpio_irq_chip *girq;
> > > > > >         int ret;
> > > > > >
> > > > > > +       parent_np = of_irq_find_parent(np);
> > > > > > +       if (!parent_np)
> > > > > > +               return -ENXIO;
> > > > > > +
> > > > > > +       parent_domain = irq_find_host(parent_np);
> > > > > > +       of_node_put(parent_np);
> > > > > > +       if (!parent_domain)
> > > > > > +               return -EPROBE_DEFER;
> > > > > > +
> > > > > >         ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3, 0, &of_args);
> > > > > >         if (ret) {
> > > > > >                 dev_err(pctrl->dev, "Unable to parse gpio-ranges\n");
> > > > > > @@ -1138,6 +1330,15 @@ static int rzg2l_gpio_register(struct rzg2l_pinctrl *pctrl)
> > > > > >         chip->base = -1;
> > > > > >         chip->ngpio = of_args.args[2];
> > > > > >
> > > > > > +       girq = &chip->irq;
> > > > > > +       girq->chip = &rzg2l_gpio_irqchip;
> > > > > > +       girq->fwnode = of_node_to_fwnode(np);
> > > > > > +       girq->parent_domain = parent_domain;
> > > > > > +       girq->child_to_parent_hwirq = rzg2l_gpio_child_to_parent_hwirq;
> > > > > > +       girq->populate_parent_alloc_arg = rzg2l_gpio_populate_parent_fwspec;
> > > > > > +       girq->child_irq_domain_ops.free = rzg2l_gpio_irq_domain_free;
> > > > > > +       girq->ngirq = RZG2L_TINT_MAX_INTERRUPT;
> > > > > > +
> > > > >
> > > > > I think you need to provide a .init_valid_mask() callback, as
> > > > > gpiochip_irqchip_remove() relies on that for destroying interrupts.
> > > > Are you suggesting  the callback to avoid looping through all the GPIO pins?
> > >
> > > gpiochip_irqchip_remove() does:
> > >
> > >         /* Remove all IRQ mappings and delete the domain */
> > >         if (gc->irq.domain) {
> > >                 unsigned int irq;
> > >
> > >                 for (offset = 0; offset < gc->ngpio; offset++) {
> > >                        if (!gpiochip_irqchip_irq_valid(gc, offset))
> > >                                 continue;
> > >
> > >                         irq = irq_find_mapping(gc->irq.domain, offset);
> > >                         irq_dispose_mapping(irq);
> > >                 }
> > >
> > >                 irq_domain_remove(gc->irq.domain);
> > >
> > >         }
> > >
> > > The main thing is not about avoiding to loop through all GPIO pins,
> > > but to avoid irq_{find,dispose}_mapping() doing the wrong thing.
> > So in our case if we don't implement valid masks, that would mean all
> > the pins are valid. irq_find_mapping() would return 0 if no mapping is
> > found to the corresponding offset and irq_dispose_mapping() would
> > simply return back without doing anything if virq == 0.(In this patch
> > rzg2l_gpio_free() does call irq_{find,dispose}_mapping())
>
> But "offset" is a number from the GPIO offset space (0-122), while

The "offset" reported by kernel is 120-511:

root@smarc-rzg2l:~# cat /sys/kernel/debug/gpio
gpiochip0: GPIOs 120-511, parent: platform/11030000.pinctrl, 11030000.pinctrl:
 gpio-120 (P0_0                )
 gpio-121 (P0_1                )
 gpio-122 (P0_2                )
 gpio-123 (P0_3                )
 gpio-124 (P0_4                )
.....
 gpio-507 (P48_3               )
 gpio-508 (P48_4               )
 gpio-509 (P48_5               )
 gpio-510 (P48_6               )
 gpio-511 (P48_7               )

> irq_find_mapping() expects a number from the domain's IRQ space,
> which is only 0-31?
>
Nope, let me demonstrate with an example, I have configured the gpio
pins as GPIO keys in DTS:

+       keyboard {
+               compatible = "gpio-keys";
+               status = "okay";
+
+               key-1 {
+                       gpios = <&pinctrl RZG2L_GPIO(43, 0) GPIO_ACTIVE_HIGH>;
+                       linux,code = <KEY_1>;
+                       linux,input-type = <EV_KEY>;
+                       wakeup-source;
+                       label = "SW1";
+               };
+
+               key-2 {
+                       gpios = <&pinctrl RZG2L_GPIO(41, 0) GPIO_ACTIVE_HIGH>;
+                       linux,code = <KEY_2>;
+                       linux,input-type = <EV_KEY>;
+                       wakeup-source;
+                       label = "SW2";
+               };
+
+               key-3 {
+                       gpios = <&pinctrl RZG2L_GPIO(43, 1) GPIO_ACTIVE_HIGH>;
+                       linux,code = <KEY_3>;
+                       linux,input-type = <EV_KEY>;
+                       wakeup-source;
+                       label = "SW3";
+               };
+       };

root@smarc-rzg2l:~# cat /proc/interrupts | grep SW
root@smarc-rzg2l:~#
root@smarc-rzg2l:~# insmod gpio_keys.ko
[  925.002720] input: keyboard as /devices/platform/keyboard/input/input3
root@smarc-rzg2l:~# cat /proc/interrupts | grep SW
 82:          0          0 11030000.pinctrl 344 Edge      SW1
 83:          0          0 11030000.pinctrl 328 Edge      SW2
 84:          0          0 11030000.pinctrl 345 Edge      SW3
root@smarc-rzg2l:~#

In here 82/83/84 are virq and 344/328/345 are hwirq, which can be
confirmed from sysfs file:

root@smarc-rzg2l:~# cat /sys/kernel/debug/irq/irqs/82
handler:  handle_fasteoi_irq
device:   (null)
status:   0x00000001
istate:   0x00000000
ddepth:   0
wdepth:   0
dstate:   0x13400201
            IRQ_TYPE_EDGE_RISING
            IRQD_ACTIVATED
            IRQD_IRQ_STARTED
            IRQD_SINGLE_TARGET
            IRQD_DEFAULT_TRIGGER_SET
            IRQD_HANDLE_ENFORCE_IRQCTX
node:     0
affinity: 0-1
effectiv:
domain:  :soc:pinctrl@11030000
 hwirq:   0x158
 chip:    11030000.pinctrl
  flags:   0x800
             IRQCHIP_IMMUTABLE
 parent:
    domain:  :soc:interrupt-controller@110a0000
     hwirq:   0x9
     chip:    rzg2l-irqc
      flags:   0x15
                 IRQCHIP_SET_TYPE_MASKED
                 IRQCHIP_MASK_ON_SUSPEND
                 IRQCHIP_SKIP_SET_WAKE
     parent:
        domain:  :soc:interrupt-controller@11900000-1
         hwirq:   0x1dc
         chip:    GICv3
          flags:   0x15
                     IRQCHIP_SET_TYPE_MASKED
                     IRQCHIP_MASK_ON_SUSPEND
                     IRQCHIP_SKIP_SET_WAKE
root@smarc-rzg2l:~#
root@smarc-rzg2l:~#
root@smarc-rzg2l:~# cat /sys/kernel/debug/irq/irqs/83
handler:  handle_fasteoi_irq
device:   (null)
status:   0x00000001
istate:   0x00000000
ddepth:   0
wdepth:   0
dstate:   0x13400201
            IRQ_TYPE_EDGE_RISING
            IRQD_ACTIVATED
            IRQD_IRQ_STARTED
            IRQD_SINGLE_TARGET
            IRQD_DEFAULT_TRIGGER_SET
            IRQD_HANDLE_ENFORCE_IRQCTX
node:     0
affinity: 0-1
effectiv:
domain:  :soc:pinctrl@11030000
 hwirq:   0x148
 chip:    11030000.pinctrl
  flags:   0x800
             IRQCHIP_IMMUTABLE
 parent:
    domain:  :soc:interrupt-controller@110a0000
     hwirq:   0xa
     chip:    rzg2l-irqc
      flags:   0x15
                 IRQCHIP_SET_TYPE_MASKED
                 IRQCHIP_MASK_ON_SUSPEND
                 IRQCHIP_SKIP_SET_WAKE
     parent:
        domain:  :soc:interrupt-controller@11900000-1
         hwirq:   0x1dd
         chip:    GICv3
          flags:   0x15
                     IRQCHIP_SET_TYPE_MASKED
                     IRQCHIP_MASK_ON_SUSPEND
                     IRQCHIP_SKIP_SET_WAKE
root@smarc-rzg2l:~#
root@smarc-rzg2l:~# cat /sys/kernel/debug/irq/irqs/84
handler:  handle_fasteoi_irq
device:   (null)
status:   0x00000001
istate:   0x00000000
ddepth:   0
wdepth:   0
dstate:   0x13400201
            IRQ_TYPE_EDGE_RISING
            IRQD_ACTIVATED
            IRQD_IRQ_STARTED
            IRQD_SINGLE_TARGET
            IRQD_DEFAULT_TRIGGER_SET
            IRQD_HANDLE_ENFORCE_IRQCTX
node:     0
affinity: 0-1
effectiv:
domain:  :soc:pinctrl@11030000
 hwirq:   0x159
 chip:    11030000.pinctrl
  flags:   0x800
             IRQCHIP_IMMUTABLE
 parent:
    domain:  :soc:interrupt-controller@110a0000
     hwirq:   0xb
     chip:    rzg2l-irqc
      flags:   0x15
                 IRQCHIP_SET_TYPE_MASKED
                 IRQCHIP_MASK_ON_SUSPEND
                 IRQCHIP_SKIP_SET_WAKE
     parent:
        domain:  :soc:interrupt-controller@11900000-1
         hwirq:   0x1de
         chip:    GICv3
          flags:   0x15
                     IRQCHIP_SET_TYPE_MASKED
                     IRQCHIP_MASK_ON_SUSPEND
                     IRQCHIP_SKIP_SET_WAKE
root@smarc-rzg2l:~#
root@smarc-rzg2l:~#
root@smarc-rzg2l:~#

root@smarc-rzg2l:~# rmmod gpio_keys.ko
[ 1143.037314] rzg2l_gpio_free offset:345 virq:84
[ 1143.042488] rzg2l_gpio_free offset:328 virq:83
[ 1143.048700] rzg2l_gpio_free offset:344 virq:82
root@smarc-rzg2l:~#
root@smarc-rzg2l:~#

I have added print in gpio_free callback where
irq_{find,dispose}_mapping()) prints the correct value above.


> > > The loop is over all GPIO offsets, while not all of them are mapped
> > > to valid interrupts. Does the above work correctly?
> > >
> > I haven't tested unloading the pinctrl driver which should call
> > gpiochip_irqchip_remove() (we don't have remove call back for pinctrl
> > driver)
> >
> > > > > However, the mask will need to be dynamic, as GPIO interrupts can be
> > > > > mapped and unmapped to one of the 32 available interrupts dynamically,
> > > > > right?
> > > > Yep that's correct.
> > > >
> > > > > I'm not sure if that can be done easily: if gpiochip_irqchip_irq_valid()
> > > > > is ever called too early, before the mapping is done, it would fail.
> > > > >
> > > > The mask initialization is a one time process and that is during
> > > > adding the GPIO chip. At this stage we won't be knowing what will be
> > > > the valid GPIO pins used as interrupts. Maybe the core needs to
> > > > implement a callback which lands in the GPIO controller driver to tell
> > > > if the gpio irq line is valid. This way we can handle dynamic
> > > > interrupts.
> > >
> > > Upon closer look, I think the mask is a red herring, and we don't
> > > need it.
> > Agreed.
> >
> > > But we do need to handle the (possible) mismatch between GPIO
> > > offset (index) and IRQ offset in the above code.
> > >
> > Agreed, do you see any possibility of the mismatch I have missed?
>
> gpiochip_to_irq():
>
>         if (irq_domain_is_hierarchy(domain)) {
>                 struct irq_fwspec spec;
>
>                 spec.fwnode = domain->fwnode;
>                 spec.param_count = 2;
>                 spec.param[0] = gc->irq.child_offset_to_irq(gc, offset);
>                 spec.param[1] = IRQ_TYPE_NONE;
>
>                 return irq_create_fwspec_mapping(&spec);
>         }
>
> Same here: in the absence of a child_offset_to_irq() callback,
> the default gpiochip_child_offset_to_irq_noop() will be used,
> assuming an identity mapping between GPIO numbers and IRQ
> numbers.
>
Agreed, gpiochip_child_offset_to_irq_noop will return the "offset",
but irq_create_fwspec_mapping() in gpiochip_to_irq() will return the
virq number which will not be equal to the offset.

I added the below change in gpio_keys.c where it calls gpiod_to_irq()
-> to_irq()  and the below is the log:
--- a/drivers/input/keyboard/gpio_keys.c
+++ b/drivers/input/keyboard/gpio_keys.c
@@ -589,6 +589,8 @@ static int gpio_keys_setup_key(struct platform_device *pdev,
                                        button->gpio, error);
                                return error;
                        }
+                       dev_err(dev,"%s gpiod_to_irq() = (irq) %d\n",
__func__, irq);
+
                        bdata->irq = irq;
                }

root@smarc-rzg2l:~# insmod gpio_keys.ko
[   54.288678] gpio-keys keyboard: gpio_keys_setup_key gpiod_to_irq() = (irq) 82
[   54.297230] gpio-keys keyboard: gpio_keys_setup_key gpiod_to_irq() = (irq) 83
[   54.311256] gpio-keys keyboard: gpio_keys_setup_key gpiod_to_irq() = (irq) 84
[   54.332560] input: keyboard as /devices/platform/keyboard/input/input0
root@smarc-rzg2l:~#

> So perhaps
>   1. you need to provide a child_offset_to_irq() callback,
>   2. gpiochip_irqchip_remove() needs to apply the child_offset_to_irq()
>     mapping too?
>   3. you do need the mask, or let child_offset_to_irq() an error code,
>      to avoid irq_{find,dispose}_mapping() handling non-existent irqs?
>
From the above logs, I don't think this is needed. Please correct me
if I am wrong.


> Or am I missing something?
>
> I guess this is easy to verify by adding some debug prints to the code.
>
Let me know if you want me to add debug prints at specific places.

Cheers,
Prabhakar