[PATCH v4 4/5] ARM: mediatek: Add EINT support to MTK pinctrl driver.

Linus Walleij linus.walleij at linaro.org
Tue Jan 13 05:24:40 PST 2015

On Tue, Jan 6, 2015 at 10:16 AM, Yingjoe Chen <yingjoe.chen at mediatek.com> wrote:
> On Wed, 2014-12-17 at 17:09 +0800, Yingjoe Chen wrote:
>> On Wed, 2014-12-17 at 07:34 +0800, Hongzhou Yang wrote:
>> > From: Maoguang Meng <maoguang.meng at mediatek.com>
>> >
>> > MTK SoC support external interrupt(EINT) from most SoC pins.
>> > Add EINT support to pinctrl driver.
>> >
>> > Signed-off-by: Maoguang Meng <maoguang.meng at mediatek.com>
>> > Signed-off-by: Hongzhou Yang <hongzhou.yang at mediatek.com>
>> Hi Linus,
>> This patch add EINT support to the pinctrl driver. We've surveyed
>> GPIOLIB_IRQCHIP, but we didn't use it because:
>> - Not every GPIO pin support interrupt.
>> - EINT use a different numbering to GPIO. eg, from the mt8135 table,
>> GPIO29 is EINT158. It is more nature & efficient to use EINT number as
>> hwirq.
>> +               MTK_EINT_FUNCTION(2, 158),
>> +               MTK_FUNCTION(0, "GPIO29"),
> After further looking into this, we could use GPIOLIB_IRQCHIP if we add
> an extension gpiochip_irqchip_add() to accept interrupt numbers and
> custom .to_irq function for our SoC. We could still reuse other code

I see, and I still want to see all possibilities to centralize code

If I understand correctly what you actually need is a linear
irqdomain with "holes" (invalid offsets) in it.
So this is what we should design for.

The .to_irq() function should not really perform anything but a
simple lookup in the domain.

What you do here:

+static int mtk_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
+       const struct mtk_desc_pin *pin;
+       struct mtk_pinctrl *pctl = dev_get_drvdata(chip->dev);
+       int irq;
+       pin = pctl->devdata->pins + offset;
+       if (pin->eint.eintnum == NO_EINT_SUPPORT)
+               return -EINVAL;
+       irq = irq_find_mapping(pctl->domain, pin->eint.eintnum);
+       if (!irq)
+               return -EINVAL;
+       return irq;

Is *avoiding* to translate some IRQs from a certain offset using
the domain, I think that is the wrong way to go.

Instead, we would need to handle these "holes" in
drivers/pinctrl/nomadik/pinctrl-abx500.c also need the same

Maybe we can add a gpiochip_irqchip_add_sparse() in
gpiolib that will take an array of bools in, indicating of
a certain line is elegible for IRQ or not, e.g.:

bool valid = { false, true, false, true };

foo = gpiochip_irqchip_add_sparse(&chip,

So the loop inside the lib will avoid calling
irq_create_mapping() on the invalid lines, and any calls
to irq_find_mapping() will fail if you try to use one of
them for IRQs.

If you're up to do this and test on your driver I'm all in for it.

Linus Walleij

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