linux-kernel - Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own

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Date:	Tue, 22 Jul 2014 09:43:48 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>
Subject: Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and
 gpiochip_free_own_desc

On Mon, Jul 21, 2014 at 10:18:25PM -0700, Guenter Roeck wrote:
> Both functions were introduced to let gpio drivers request their own
> gpio pins. Without exporting the functions, this can however only be
> used by gpio drivers built into the kernel.

The reason why these are private to drivers is that those are dangerous
if used blindly.

> Secondary impact is that the functions can not currently be used by
> platform initialization code associated with the gpio-pca953x driver.
> This code permits auto-export of gpio pins through platform data, but
> if this functionality is used, the module can no longer be unloaded due
> to the problem solved with the introduction of gpiochip_request_own_desc
> and gpiochip_free_own_desc.
> 
> Export both function so they can be used from modules and from
> platform initialization code.

However, you have valid reason above. I wonder if this requires
some documentation in Documentation/gpio/driver.txt?

> Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
> v2: Move function declarations from consumer.h to driver.h.
> 
>  drivers/gpio/gpiolib.c      | 2 ++
>  drivers/gpio/gpiolib.h      | 3 ---
>  include/linux/gpio/driver.h | 3 +++
>  3 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index 43d9e34..04c647e 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1953,6 +1953,7 @@ int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label)
>  
>  	return __gpiod_request(desc, label);
>  }
> +EXPORT_SYMBOL(gpiochip_request_own_desc);

EXPORT_SYMBOL_GPL?

>  
>  /**
>   * gpiochip_free_own_desc - Free GPIO requested by the chip driver
> @@ -1966,6 +1967,7 @@ void gpiochip_free_own_desc(struct gpio_desc *desc)
>  	if (desc)
>  		__gpiod_free(desc);
>  }
> +EXPORT_SYMBOL(gpiochip_free_own_desc);

ditto.

>  /* Drivers MUST set GPIO direction before making get/set calls.  In
>   * some cases this is done in early boot, before IRQs are enabled.
> diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h
> index 1a4103d..2bdb69d 100644
> --- a/drivers/gpio/gpiolib.h
> +++ b/drivers/gpio/gpiolib.h
> @@ -45,9 +45,6 @@ acpi_get_gpiod_by_index(struct device *dev, int index,
>  }
>  #endif
>  
> -int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label);
> -void gpiochip_free_own_desc(struct gpio_desc *desc);
> -
>  struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
>  		   const char *list_name, int index, enum of_gpio_flags *flags);
>  
> diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
> index 573e4f3..8e07d58 100644
> --- a/include/linux/gpio/driver.h
> +++ b/include/linux/gpio/driver.h
> @@ -223,6 +223,9 @@ int gpiochip_irqchip_add(struct gpio_chip *gpiochip,
>  
>  #endif /* CONFIG_GPIO_IRQCHIP */
>  
> +int gpiochip_request_own_desc(struct gpio_desc *desc, const char *label);
> +void gpiochip_free_own_desc(struct gpio_desc *desc);
> +
>  #else /* CONFIG_GPIOLIB */
>  
>  static inline struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)
> -- 
> 1.9.1
--
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