linux-kernel - Re: [PATCH RESEND] gpio: add flags to export GPIOs when requesting

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Date:	Fri, 6 Jan 2012 16:27:41 +0100
From:	Wolfram Sang <w.sang@...gutronix.de>
To:	linux-kernel@...r.kernel.org
Cc:	Grant Likely <grant.likely@...retlab.ca>,
	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dia.com>,
	Denis Kuzmenko <linux@...onet.org.ua>,
	Dong Aisheng-B29396 <B29396@...escale.com>
Subject: Re: [PATCH RESEND] gpio: add flags to export GPIOs when requesting

On Tue, Dec 13, 2011 at 06:34:01PM +0100, Wolfram Sang wrote:
> Introduce new flags to automatically export GPIOs when using the convenience
> functions gpio_request_one() or gpio_request_array(). This eases support for
> custom boards where lots of GPIOs need to be exported for customer
> applications.
> 
> Signed-off-by: Wolfram Sang <w.sang@...gutronix.de>
> ---
> 
> Based on 3.2-rc5. Previous discussion (with kind of acks) can be found here
> 
> http://lkml.org/lkml/2011/11/15/378

Ping. I am using this patch with v3.2 right now and it is really useful
(and no build failure this time (I owe you a drink for my last patch!))

> 
>  Documentation/gpio.txt |    3 +++
>  drivers/gpio/gpiolib.c |   12 +++++++++++-
>  include/linux/gpio.h   |    5 +++++
>  3 files changed, 19 insertions(+), 1 deletions(-)
> 
> diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
> index 792faa3..9e28c05 100644
> --- a/Documentation/gpio.txt
> +++ b/Documentation/gpio.txt
> @@ -303,6 +303,9 @@ where 'flags' is currently defined to specify the following properties:
>  	* GPIOF_INIT_LOW	- as output, set initial level to LOW
>  	* GPIOF_INIT_HIGH	- as output, set initial level to HIGH
>  
> +	* GPIOF_EXPORT_DIR_FIXED	- export gpio to sysfs, keep direction
> +	* GPIOF_EXPORT_DIR_CHANGEABLE	- also export, allow changing direction
> +
>  since GPIOF_INIT_* are only valid when configured as output, so group valid
>  combinations as:
>  
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a971e3d..65ba047 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1285,8 +1285,18 @@ int gpio_request_one(unsigned gpio, unsigned long flags, const char *label)
>  				(flags & GPIOF_INIT_HIGH) ? 1 : 0);
>  
>  	if (err)
> -		gpio_free(gpio);
> +		goto free_gpio;
> +
> +	if (flags & GPIOF_EXPORT) {
> +		err = gpio_export(gpio, flags & GPIOF_EXPORT_CHANGEABLE);
> +		if (err)
> +			goto free_gpio;
> +	}
> +
> +	return 0;
>  
> + free_gpio:
> +	gpio_free(gpio);
>  	return err;
>  }
>  EXPORT_SYMBOL_GPL(gpio_request_one);
> diff --git a/include/linux/gpio.h b/include/linux/gpio.h
> index 38ac48b..38afe24 100644
> --- a/include/linux/gpio.h
> +++ b/include/linux/gpio.h
> @@ -14,6 +14,11 @@
>  #define GPIOF_OUT_INIT_LOW	(GPIOF_DIR_OUT | GPIOF_INIT_LOW)
>  #define GPIOF_OUT_INIT_HIGH	(GPIOF_DIR_OUT | GPIOF_INIT_HIGH)
>  
> +#define GPIOF_EXPORT		(1 << 2)
> +#define GPIOF_EXPORT_CHANGEABLE	(1 << 3)
> +#define GPIOF_EXPORT_DIR_FIXED	(GPIOF_EXPORT)
> +#define GPIOF_EXPORT_DIR_CHANGEABLE (GPIOF_EXPORT | GPIOF_EXPORT_CHANGEABLE)
> +
>  /**
>   * struct gpio - a structure describing a GPIO with configuration
>   * @gpio:	the GPIO number
> -- 
> 1.7.2.5
> 

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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