linux-kernel - Re: [PATCH 1/2] gpiolib: introduce gpio_set

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Date:	Fri, 25 Nov 2011 16:16:41 +0200
From:	Felipe Balbi <balbi@...com>
To:	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Cc:	linux-kernel@...r.kernel.org,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [PATCH 1/2] gpiolib: introduce gpio_set_pullup

Hi,

On Fri, Nov 25, 2011 at 03:08:39PM +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
> Cc: Nicolas Ferre <nicolas.ferre@...el.com>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> ---
>  drivers/gpio/gpiolib.c     |   44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/asm-generic/gpio.h |    4 ++++
>  include/linux/gpio.h       |    5 +++++
>  3 files changed, 53 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a971e3d..b7e5e75 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1519,6 +1519,50 @@ fail:
>  }
>  EXPORT_SYMBOL_GPL(gpio_set_debounce);
>  
> +/**
> + * gpio_set_pullup - sets @pullup for a @gpio
> + * @gpio: the gpio to set pullup
> + * @pullup: pullup level
> + */
> +int gpio_set_pullup(unsigned gpio, unsigned pullup)
> +{
> +	unsigned long		flags;
> +	struct gpio_chip	*chip;
> +	struct gpio_desc	*desc = &gpio_desc[gpio];
> +	int			status = -EINVAL;
> +
> +	spin_lock_irqsave(&gpio_lock, flags);
> +
> +	if (!gpio_is_valid(gpio))
> +		goto fail;
> +	chip = desc->chip;
> +	if (!chip || !chip->set_pullup)
> +		goto fail;
> +	gpio -= chip->base;
> +	if (gpio >= chip->ngpio)
> +		goto fail;
> +	status = gpio_ensure_requested(desc, gpio);
> +	if (status < 0)
> +		goto fail;
> +
> +	/* now we know the gpio is valid and chip won't vanish */
> +
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +
> +	might_sleep_if(chip->can_sleep);
> +
> +	return chip->set_pullup(chip, gpio, pullup);
> +
> +fail:
> +	spin_unlock_irqrestore(&gpio_lock, flags);
> +	if (status)
> +		pr_debug("%s: gpio-%d status %d\n",
> +			__func__, gpio, status);
> +
> +	return status;
> +}
> +EXPORT_SYMBOL_GPL(gpio_set_pullup);

Maybe I'm missing something, but isn't it essentially what
gpio_set_value() does ? I mean, you set a pullup and you get '1' value
and set a pulldown and you get a '0' value ??

Without a proper description of the necessity for this change, I can't
easily tell them apart :-(

-- 
balbi

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