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SubjectRe: [PATCH v3 5/5] pinctrl: renesas: pinctrl-rzg2l: Add IRQ domain to handle GPIO interrupt
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

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