linux-kernel - Re: [PATCH v3 3/7] gpiolib: Add support for GPIO line table lookup

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Date:   Thu, 28 Nov 2019 04:39:14 +0100 (CET)
From:   Ulrich Hecht <uli@...nd.eu>
To:     Geert Uytterhoeven <geert+renesas@...der.be>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Jonathan Corbet <corbet@....net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Harish Jenny K N <harish_kandiga@...tor.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>
Cc:     Alexander Graf <graf@...zon.com>,
        Peter Maydell <peter.maydell@...aro.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Phil Reid <preid@...ctromag.com.au>,
        Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Magnus Damm <magnus.damm@...il.com>,
        linux-gpio@...r.kernel.org, linux-doc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org, qemu-devel@...gnu.org
Subject: Re: [PATCH v3 3/7] gpiolib: Add support for GPIO line table lookup


> On November 27, 2019 at 9:42 AM Geert Uytterhoeven <geert+renesas@...der.be> wrote:
> 
> 
> Currently GPIOs can only be referred to by GPIO controller and offset in
> GPIO lookup tables.
> 
> Add support for looking them up by line name.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> If this is rejected, the GPIO Aggregator documentation and code must be
> updated.
> 
> v3:
>   - New.
> ---
>  drivers/gpio/gpiolib.c       | 12 ++++++++++++
>  include/linux/gpio/machine.h |  2 +-
>  2 files changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index d24a3d79dcfe69ad..cb608512ad6bbded 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -4475,6 +4475,18 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
>  		if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
>  			continue;
>  
> +		if (p->chip_hwnum == (u16)-1) {
> +			desc = gpio_name_to_desc(p->chip_label);
> +			if (desc) {
> +				*flags = p->flags;
> +				return desc;
> +			}
> +
> +			dev_warn(dev, "cannot find GPIO line %s, deferring\n",
> +				 p->chip_label);
> +			return ERR_PTR(-EPROBE_DEFER);
> +		}
> +
>  		chip = find_chip_by_name(p->chip_label);
>  
>  		if (!chip) {
> diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
> index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
> --- a/include/linux/gpio/machine.h
> +++ b/include/linux/gpio/machine.h
> @@ -31,7 +31,7 @@ enum gpio_lookup_flags {
>   */
>  struct gpiod_lookup {
>  	const char *chip_label;
> -	u16 chip_hwnum;
> +	u16 chip_hwnum;			/* if -1, chip_label is named line */

The magic number "-1" might deserve a #define.

>  	const char *con_id;
>  	unsigned int idx;
>  	unsigned long flags;
> -- 
> 2.17.1
>

With or without #define,
Reviewed-by: Ulrich Hecht <uli+renesas@...nd.eu>

CU
Uli