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gpio: Introduce ->get_multiple callback

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SPI-attached GPIO controllers typically read out all inputs in one go.
If callers desire the values of multipe inputs, ideally a single readout
should take place to return the desired values.  However the current
driver API only offers a ->get callback but no ->get_multiple (unlike
->set_multiple, which is present).  Thus, to read multiple inputs, a
full readout needs to be performed for every single value (barring
driver-internal caching), which is inefficient.

In fact, the lack of a ->get_multiple callback has been bemoaned
repeatedly by the gpio subsystem maintainer:
http://www.spinics.net/lists/linux-gpio/msg10571.html
http://www.spinics.net/lists/devicetree/msg121734.html

Introduce the missing callback.  Add corresponding consumer functions
such as gpiod_get_array_value().  Amend linehandle_ioctl() to take
advantage of the newly added infrastructure.  Update the documentation.

Cc: Rojhalat Ibrahim <imr@rtschenk.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Lukas Wunner 2017-10-12 12:40:10 +02:00 • committed by Linus Walleij
parent 5307e2ad69
commit eec1d566cd
5 changed files with 250 additions and 22 deletions
Download patch file Download diff file Expand all files Collapse all files

43
include/linux/gpio/consumer.h
View file

@ -99,10 +99,15 @@ int gpiod_direction_output_raw(struct gpio_desc *desc, int value);
/* Value get/set from non-sleeping context */
int gpiod_get_value(const struct gpio_desc *desc);
int gpiod_get_array_value(unsigned int array_size,
struct gpio_desc **desc_array, int *value_array);
void gpiod_set_value(struct gpio_desc *desc, int value);
void gpiod_set_array_value(unsigned int array_size,
struct gpio_desc **desc_array, int *value_array);
int gpiod_get_raw_value(const struct gpio_desc *desc);
int gpiod_get_raw_array_value(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array);
void gpiod_set_raw_value(struct gpio_desc *desc, int value);
void gpiod_set_raw_array_value(unsigned int array_size,
struct gpio_desc **desc_array,
@ -110,11 +115,17 @@ void gpiod_set_raw_array_value(unsigned int array_size,
/* Value get/set from sleeping context */
int gpiod_get_value_cansleep(const struct gpio_desc *desc);
int gpiod_get_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array);
void gpiod_set_value_cansleep(struct gpio_desc *desc, int value);
void gpiod_set_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array);
int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc);
int gpiod_get_raw_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array);
void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value);
void gpiod_set_raw_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
@ -305,6 +316,14 @@ static inline int gpiod_get_value(const struct gpio_desc *desc)
WARN_ON(1);
return 0;
}
static inline int gpiod_get_array_value(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array)
{
/* GPIO can never have been requested */
WARN_ON(1);
return 0;
}
static inline void gpiod_set_value(struct gpio_desc *desc, int value)
{
/* GPIO can never have been requested */
@ -323,6 +342,14 @@ static inline int gpiod_get_raw_value(const struct gpio_desc *desc)
WARN_ON(1);
return 0;
}
static inline int gpiod_get_raw_array_value(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array)
{
/* GPIO can never have been requested */
WARN_ON(1);
return 0;
}
static inline void gpiod_set_raw_value(struct gpio_desc *desc, int value)
{
/* GPIO can never have been requested */
@ -342,6 +369,14 @@ static inline int gpiod_get_value_cansleep(const struct gpio_desc *desc)
WARN_ON(1);
return 0;
}
static inline int gpiod_get_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array)
{
/* GPIO can never have been requested */
WARN_ON(1);
return 0;
}
static inline void gpiod_set_value_cansleep(struct gpio_desc *desc, int value)
{
/* GPIO can never have been requested */
@ -360,6 +395,14 @@ static inline int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)
WARN_ON(1);
return 0;
}
static inline int gpiod_get_raw_array_value_cansleep(unsigned int array_size,
struct gpio_desc **desc_array,
int *value_array)
{
/* GPIO can never have been requested */
WARN_ON(1);
return 0;
}
static inline void gpiod_set_raw_value_cansleep(struct gpio_desc *desc,
int value)
{