linux-kernel - Re: [PATCH 4/5] pinctrl: actions: Add gpio support for Actions S900 SoC

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Date:   Sat, 19 May 2018 11:18:53 +0200
From:   Christian Lamparter <chunkeey@...il.com>
To:     Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Cc:     linus.walleij@...aro.org, robh+dt@...nel.org, afaerber@...e.de,
        liuwei@...ions-semi.com, mp-cs@...ions-semi.com,
        96boards@...obotics.com, devicetree@...r.kernel.org,
        andy.shevchenko@...il.com, daniel.thompson@...aro.org,
        amit.kucheria@...aro.org, linux-arm-kernel@...ts.infradead.org,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        hzhang@...obotics.com, bdong@...obotics.com,
        manivannanece23@...il.com
Subject: Re: [PATCH 4/5] pinctrl: actions: Add gpio support for Actions S900 SoC

On Friday, May 18, 2018 4:30:55 AM CEST Manivannan Sadhasivam wrote:
> Add gpio support to pinctrl driver for Actions Semi S900 SoC.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
> [...]
> +static int owl_gpio_init(struct owl_pinctrl *pctrl)
> +{
> +	struct gpio_chip *chip;
> +	int ret;
> +
> +	chip = &pctrl->chip;
> +	chip->base = -1;
> +	chip->ngpio = pctrl->soc->ngpios;
> +	chip->label = dev_name(pctrl->dev);
> +	chip->parent = pctrl->dev;
> +	chip->owner = THIS_MODULE;
> +	chip->of_node = pctrl->dev->of_node;
> +
> +	ret = gpiochip_add_data(&pctrl->chip, pctrl);
> +	if (ret) {
> +		dev_err(pctrl->dev, "failed to register gpiochip\n");
> +		return ret;
> +	}
> +
> +	ret = gpiochip_add_pin_range(&pctrl->chip, dev_name(pctrl->dev),
> +							0, 0, chip->ngpio);
> +	if (ret) {
> +		dev_err(pctrl->dev, "failed to add pin range\n");
> +		gpiochip_remove(&pctrl->chip);
> +		return ret;
> +	}
> +
gpiochip_add_pin_range()? That's not going to work with gpio-hogs. 

But, you can easily test this. Just add a gpio-hog [0] 
( Section 2. gpio-controller nodes) into the Devicetree's
pinctrl node.

something like: (No idea if GPIO1 is already used, but any free
gpio will do)
| 		[...]
|		pinctrl@...b0000 {
|			compatible = "actions,s900-pinctrl";
|			reg = <0x0 0xe01b0000 0x0 0x1000>;
|			clocks = <&cmu CLK_GPIO>;
|			gpio-controller;
|			#gpio-cells = <2>;
|
|			line_b {
|				gpio-hog;
|				gpios = <1 GPIO_ACTIVE_HIGH>;
|				output-low;
|				line-name = "foo-bar-gpio";
|			};
|		};

The pinctrl probe will fail. You can fix this by
replacing the gpiochip_add_pin_range() and use
the gpio-ranges [0] property to define the range.

[0] <https://www.kernel.org/doc/Documentation/devicetree/bindings/gpio/gpio.txt>