gpio: return NULL from gpiod_get_optional when GPIOLIB is disabled
Given the intent behind gpiod_get_optional() and friends it does not make
sense to return -ENOSYS when GPIOLIB is disabled: the driver is expected to
work just fine without gpio so let's behave as if gpio was not found.
Otherwise we have to special-case -ENOSYS in drivers.
Note that there was objection that someone might forget to enable GPIOLIB
when dealing with a platform that has device that actually specifies
optional gpio and we'll break it. I find this unconvincing as that would
have to be the *only GPIO* in the system, which is extremely unlikely.
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt
index 05676fd..912568b 100644
--- a/Documentation/gpio/consumer.txt
+++ b/Documentation/gpio/consumer.txt
@@ -70,6 +70,12 @@
unsigned int index,
enum gpiod_flags flags)
+Note that gpio_get*_optional() functions (and their managed variants), unlike
+the rest of gpiolib API, also return NULL when gpiolib support is disabled.
+This is helpful to driver authors, since they do not need to special case
+-ENOSYS return codes. System integrators should however be careful to enable
+gpiolib on systems that need it.
+
For a function using multiple GPIOs all of those can be obtained with one call:
struct gpio_descs *gpiod_get_array(struct device *dev,
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index 2484b2f..13daf08 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -179,14 +179,14 @@
gpiod_get_optional(struct device *dev, const char *con_id,
enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline struct gpio_desc *__must_check
gpiod_get_index_optional(struct device *dev, const char *con_id,
unsigned int index, enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline struct gpio_descs *__must_check
@@ -200,7 +200,7 @@
gpiod_get_array_optional(struct device *dev, const char *con_id,
enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline void gpiod_put(struct gpio_desc *desc)
@@ -240,14 +240,14 @@
devm_gpiod_get_optional(struct device *dev, const char *con_id,
enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline struct gpio_desc *__must_check
devm_gpiod_get_index_optional(struct device *dev, const char *con_id,
unsigned int index, enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline struct gpio_descs *__must_check
@@ -261,7 +261,7 @@
devm_gpiod_get_array_optional(struct device *dev, const char *con_id,
enum gpiod_flags flags)
{
- return ERR_PTR(-ENOSYS);
+ return NULL;
}
static inline void devm_gpiod_put(struct device *dev, struct gpio_desc *desc)