linux-kernel - Re: gpiolib: add export/unexport by gpio name

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Message-ID: <20090803170446.GA25100@fluff.org.uk>
Date:	Mon, 3 Aug 2009 18:04:46 +0100
From:	Ben Dooks <ben-linux@...ff.org>
To:	ben@...ff.org
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	David Brownell <dbrownell@...rs.sourceforge.net>
Subject: Re: gpiolib: add export/unexport by gpio name

On Mon, Aug 03, 2009 at 05:55:44PM +0100, ben@...ff.org wrote:
> Add the facility to export/unexport a gpio by the name assigned to it
> as well as the number.

sorry, forgot to update the patch before sending, please ignore this
one.
 
> Signed-off-by: Ben Dooks <ben@...tec.co.uk>
> Cc: David Brownell <dbrownell@...rs.sourceforge.net>
> 
> ---
>  drivers/gpio/gpiolib.c |   59 +++++++++++++++++++++++++++++++++++++++++++++----
>  1 file changed, 55 insertions(+), 4 deletions(-)
> 
> Index: b/drivers/gpio/gpiolib.c
> ===================================================================
> --- a/drivers/gpio/gpiolib.c	2009-08-03 17:53:04.000000000 +0100
> +++ b/drivers/gpio/gpiolib.c	2009-08-03 17:53:33.000000000 +0100
> @@ -364,6 +364,53 @@ static const struct attribute_group gpio
>  	.attrs = (struct attribute **) gpiochip_attrs,
>  };
>  
> +static int search_names(char **names, const char *match, int ngpio)
> +{
> +	int ptr;
> +
> +	if (names) {
> +		for (ptr = 0; ptr < ngpio; ptr++) {
> +			if (!names[ptr])
> +				continue;
> +
> +			if (strcmp(names[ptr], match) == 0)
> +				return ptr;
> +		}
> +	}
> +
> +	return -ENOENT;
> +}
> +
> +static long gpio_from_string(const char *buf)
> +{
> +	struct gpio_chip *chip;
> +	struct gpio_desc *desc;
> +	long status;
> +	long gpio;
> +	int ptr, off;
> +
> +	status = strict_strtol(buf, 0, &gpio);
> +	if (status < 0) {
> +		for (ptr = 0; ptr < ARCH_NR_GPIOS && status < 0;) {
> +			desc = gpio_desc + ptr;
> +			chip = desc->chip;
> +
> +			if (!chip) {
> +				ptr++;
> +				continue;
> +			}
> +
> +			off = search_names(chip->names, buf, chip->ngpio);
> +			if (off >= 0)
> +				status = ptr + off;
> +
> +			ptr += chip->ngpio;
> +		}
> +	}
> +
> +	return status;
> +}
> +
>  /*
>   * /sys/class/gpio/export ... write-only
>   *	integer N ... number of GPIO to export (full access)
> @@ -375,9 +422,11 @@ static ssize_t export_store(struct class
>  	long	gpio;
>  	int	status;
>  
> -	status = strict_strtol(buf, 0, &gpio);
> -	if (status < 0)
> +	gpio = gpio_from_string(buf);
> +	if (gpio < 0) {
> +		status = gpio;
>  		goto done;
> +	}
>  
>  	/* No extra locking here; FLAG_SYSFS just signifies that the
>  	 * request and export were done by on behalf of userspace, so
> @@ -405,9 +454,11 @@ static ssize_t unexport_store(struct cla
>  	long	gpio;
>  	int	status;
>  
> -	status = strict_strtol(buf, 0, &gpio);
> -	if (status < 0)
> +	gpio = gpio_from_string(buf);
> +	if (gpio < 0) {
> +		status = gpio;
>  		goto done;
> +	}
>  
>  	status = -EINVAL;
>  
> 
> -- 
> --
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-- 
Ben (ben@...ff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'
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