[PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[Guenter Roeck]

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.

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.

Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Guenter Roeck <linux@roeck-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);
 
 /**
  * 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);
 
 /* 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

Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[Mika Westerberg]

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@linux.intel.com>
> Signed-off-by: Guenter Roeck <linux@roeck-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

Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[Alexandre Courbot]

On Tue, Jul 22, 2014 at 3:43 PM, Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
> 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?

Indeed, that would be nice - at least to explain that these are not to
be used inconsiderably.

>
>> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
>> Signed-off-by: Guenter Roeck <linux@roeck-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

Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[Guenter Roeck]

On 07/21/2014 11:43 PM, Mika Westerberg wrote:
> 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?
>
Sure. Any idea what I should write, or do you want me to come up with something ?

>> Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
>> Signed-off-by: Guenter Roeck <linux@roeck-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?
>
Ok.

Thanks,
Guenter

Re: [PATCH v2] gpiolib: Export gpiochip_request_own_desc and gpiochip_free_own_desc

[Mika Westerberg]

On Mon, Jul 21, 2014 at 11:53:27PM -0700, Guenter Roeck wrote:
> On 07/21/2014 11:43 PM, Mika Westerberg wrote:
> >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?
> >
> Sure. Any idea what I should write, or do you want me to come up with something ?

Come up with something that lists valid usage of these two functions :)

Mainly that they are supposed to be used by GPIO chip drivers to request
their own GPIOs, not consumer drivers etc. And even in GPIO chip drivers
they should be used sparingly.

> 
> >>Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
> >>Signed-off-by: Guenter Roeck <linux@roeck-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?
> >
> Ok.
> 
> Thanks,
> Guenter