linux-kernel - Re: [PATCH 5/5] i2c-mux-gpio: Create of-based GPIOs request method

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Date:   Wed, 24 Apr 2019 21:27:05 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     Serge Semin <fancer.lancer@...il.com>,
        Peter Korsgaard <peter.korsgaard@...co.com>
CC:     Serge Semin <Sergey.Semin@...latforms.ru>,
        "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/5] i2c-mux-gpio: Create of-based GPIOs request method

On 2019-04-24 14:34, Serge Semin wrote:
> Most modern platforms provide a dts with description of the devices
> available in the system. It may also include i2c-gpio-mux'es.
> Up until now the i2c-mux-gpio driver supported it' dts nodes, but
> performed the GPIOs request by means of legacy GPIO API, which by design
> and due to being legacy doesn't know anything about of/dtb/fdt/dts stuff.
> It means even though the i2c-gpio-mux dts nodes are successfully mapped
> to the kernel i2c-mux devices, the GPIOs used for initialization are
> requested without OF_GPIO_* flags setup. It causes problems on the
> platforms which fully rely on dts and reside, for instance,
> i2c-gpio-muxes with active low or open drain GPIOs connected.
> 
> It is fixed by implementing a dedicated method for full dts-based
> GPIOs requests. It is mostly similar to the platform one, but
> utilizes the gpiod_get_from_of_node() method to request the GPIOs.
> 
> Finally the platform code i2c-gpio-mux devices are also supported.
> So the fallback to dtb is performed only if array with GPIOs isn't
> detected.
> 
> Signed-off-by: Serge Semin <fancer.lancer@...il.com>
> ---
>  drivers/i2c/muxes/i2c-mux-gpio.c | 65 ++++++++++++++++++++++++--------
>  1 file changed, 50 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-gpio.c b/drivers/i2c/muxes/i2c-mux-gpio.c
> index 317c019e1415..e5e10ba35ad9 100644
> --- a/drivers/i2c/muxes/i2c-mux-gpio.c
> +++ b/drivers/i2c/muxes/i2c-mux-gpio.c
> @@ -65,8 +65,8 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
>  	struct device_node *np = pdev->dev.of_node;
>  	struct device_node *adapter_np, *child;
>  	struct i2c_adapter *adapter;
> -	unsigned *values, *gpios;
> -	int i = 0, ret;
> +	unsigned int *values;
> +	int i = 0;
>  
>  	if (!np)
>  		return -ENODEV;
> @@ -109,24 +109,48 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
>  		return -EINVAL;
>  	}
>  
> -	gpios = devm_kcalloc(&pdev->dev,
> -			     mux->data.n_gpios, sizeof(*mux->data.gpios),
> -			     GFP_KERNEL);
> -	if (!gpios) {
> -		dev_err(&pdev->dev, "Cannot allocate gpios array");
> -		return -ENOMEM;
> -	}
> +	return 0;
> +}
> +
> +static int i2c_mux_gpio_request_dt(struct gpiomux *mux,
> +					struct platform_device *pdev)
> +{
> +	struct i2c_mux_core *muxc = platform_get_drvdata(pdev);
> +	struct device_node *np = pdev->dev.of_node;
> +	struct i2c_adapter *root;
> +	struct device *gpio_dev;
> +	enum gpiod_flags dflags;
> +	int i, ret;
> +
> +	root = i2c_root_adapter(&muxc->parent->dev);
>  
>  	for (i = 0; i < mux->data.n_gpios; i++) {
> -		ret = of_get_named_gpio(np, "mux-gpios", i);
> -		if (ret < 0)
> -			return ret;
> -		gpios[i] = ret;
> -	}
> +		if (mux->data.idle & (1 << i))
> +			dflags = GPIOD_OUT_HIGH;
> +		else
> +			dflags = GPIOD_OUT_LOW;
> +
> +		mux->gpios[i] = gpiod_get_from_of_node(np, "mux-gpios", i,
> +						       dflags, "i2c-mux-gpio");
> +		if (IS_ERR(mux->gpios[i])) {
> +			ret = PTR_ERR(mux->gpios[i]);
> +			goto err_request_gpio;
> +		}
>  
> -	mux->data.gpios = gpios;
> +		if (!muxc->mux_locked)
> +			continue;
> +
> +		gpio_dev = &mux->gpios[i]->gdev->dev;
> +		muxc->mux_locked = i2c_root_adapter(gpio_dev) == root;
> +	}
>  
>  	return 0;
> +
> +err_request_gpio:
> +	for (i--; i >= 0; i--)
> +		gpiod_free(mux->gpios[i]);
> +
> +	return ret;
>  }
>  #else
>  static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
> @@ -134,6 +158,12 @@ static int i2c_mux_gpio_probe_dt(struct gpiomux *mux,
>  {
>  	return -EINVAL;
>  }
> +
> +static int i2c_mux_gpio_request_dt(struct gpiomux *mux,
> +					struct platform_device *pdev)
> +{
> +	return -EINVAL;
> +}
>  #endif
>  
>  static int i2c_mux_gpio_probe_plat(struct gpiomux *mux,
> @@ -174,6 +204,9 @@ static int i2c_mux_gpio_request_plat(struct gpiomux *mux,
>  	struct device *gpio_dev;
>  	int i, ret;
>  
> +	if (!mux->data.gpios)
> +		return -EINVAL;
> +
>  	root = i2c_root_adapter(&muxc->parent->dev);
>  
>  	for (i = 0; i < mux->data.n_gpios; i++) {
> @@ -267,6 +300,8 @@ static int i2c_mux_gpio_probe(struct platform_device *pdev)
>  		mux->data.idle = mux->data.values[0];
>  
>  	ret = i2c_mux_gpio_request_plat(mux, pdev);
> +	if (ret)
> +		ret = i2c_mux_gpio_request_dt(mux, pdev);
>  	if (ret)
>  		goto alloc_failed;

Same pattern as for 2/5; any and all errors from i2c_mux_gpio_request_plat
are now lost.

Cheers,
Peter

>  
>