linux-kernel - Re: [PATCH v3 11/16] gpio: add support for the sl28cpld GPIO controller

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Date:   Mon, 27 Apr 2020 19:58:22 +0200
From:   Michael Walle <michael@...le.cc>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-gpio@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
        linux-pwm@...r.kernel.org, linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Shawn Guo <shawnguo@...nel.org>, Li Yang <leoyang.li@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>, Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH v3 11/16] gpio: add support for the sl28cpld GPIO
 controller

Am 2020-04-27 13:45, schrieb Thomas Gleixner:
> Michael Walle <michael@...le.cc> writes:
>> +struct sl28cpld_gpio {
>> +	struct regmap_irq_chip irq_chip;
>> +	struct regmap_irq_chip_data *irq_data;
>> +};
>> +
>> +static const struct regmap_irq sl28cpld_gpio_irqs[] = {
>> +	REGMAP_IRQ_REG_LINE(0, 8),
>> +	REGMAP_IRQ_REG_LINE(1, 8),
>> +	REGMAP_IRQ_REG_LINE(2, 8),
>> +	REGMAP_IRQ_REG_LINE(3, 8),
>> +	REGMAP_IRQ_REG_LINE(4, 8),
>> +	REGMAP_IRQ_REG_LINE(5, 8),
>> +	REGMAP_IRQ_REG_LINE(6, 8),
>> +	REGMAP_IRQ_REG_LINE(7, 8),
>> +};
> 
> This is exactly the same as the one in the irq chip patch.

To my knowledge this boilerplate is just to describe this
irqchip has 8 different IRQs.

>> +static int sl28cpld_gpio_irq_init(struct device *dev,
>> +				  struct sl28cpld_gpio *gpio,
>> +				  struct regmap *regmap, unsigned int base,
>> +				  int irq)
>> +{
>> +	struct regmap_irq_chip *irq_chip = &gpio->irq_chip;
>> +
>> +	irq_chip->name = "sl28cpld-gpio-irq",
>> +	irq_chip->irqs = sl28cpld_gpio_irqs;
>> +	irq_chip->num_irqs = ARRAY_SIZE(sl28cpld_gpio_irqs);
>> +	irq_chip->num_regs = 1;
>> +	irq_chip->status_base = base + GPIO_REG_IP;
>> +	irq_chip->mask_base = base + GPIO_REG_IE;
>> +	irq_chip->mask_invert = true,
>> +	irq_chip->ack_base = base + GPIO_REG_IP;
>> +
>> +	return devm_regmap_add_irq_chip_np(dev, dev_of_node(dev), regmap,
>> +					   irq, IRQF_SHARED | IRQF_ONESHOT, 0,
>> +					   irq_chip, &gpio->irq_data);
>> +}
> 
> And this looks pretty familiar as well. What's the point of duplicating
> that code?

this is also just boilerplate to configure the irqchip. But there are 
two
distinct blocks inside the board management controller:
  - an interrupt controller (which has 8 interrupts)
  - and gpio controllers which also happen to have 8 interrupts and
    both have some shared semantics for now. But the GPIO building block
    might be extended to provide interrupt type settings, i.e. falling/
    rising/level triggered interrupts.

So yes both look similar, but they are two different blocks, they use
different registers and they might drift apart in the future.

-michael

> 
> Thanks,
> 
>         tglx