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

Alexandre Courbot
2014-07-22T06:47:52Z

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