From eec1d566cdf94b57e8f5ba9fe60eea214929bcfc Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Thu, 12 Oct 2017 12:40:10 +0200 Subject: gpio: Introduce ->get_multiple callback 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 Signed-off-by: Lukas Wunner Signed-off-by: Linus Walleij --- include/linux/gpio/consumer.h | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) (limited to 'include/linux/gpio/consumer.h') diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 8f702fcbe485..d4920ec1f1da 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -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) { -- cgit v1.2.3 From f926dfc112bc6cf41d7068ee5e3f261e13a5bec8 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Sun, 10 Sep 2017 19:26:22 +0200 Subject: gpio: Make it possible for consumers to enforce open drain Some busses, like I2C, strictly need to have the line handled as open drain, i.e. not actively driven high. For this reason the i2c-gpio.c bit-banged I2C driver is reimplementing open drain handling outside of gpiolib. This is not very optimal. Instead make it possible for a consumer to explcitly express that the line must be handled as open drain instead of allowing local hacks papering over this issue. The descriptor tables, whether DT, ACPI or board files, should of course have flagged these lines as open drain. E.g.: enum gpio_lookup_flags GPIO_OPEN_DRAIN for a board file, or gpios = <&foo 42 GPIO_ACTIVE_HIGH|GPIO_OPEN_DRAIN>; in a device tree using But more often than not, these descriptors are wrong. So we need to make it possible for consumers to enforce this open drain behaviour. We now have two new enumerated GPIO descriptor config flags: GPIOD_OUT_LOW_OPEN_DRAIN and GPIOD_OUT_HIGH_OPEN_DRAIN that will set up the lined enforced as open drain as output low or high, using open drain (if the driver supports it) or using open drain emulation (setting the line as input to drive it high) from the gpiolib core. Cc: linux-gpio@vger.kernel.org Tested-by: Geert Uytterhoeven Signed-off-by: Linus Walleij --- drivers/gpio/gpiolib.c | 13 +++++++++++++ include/linux/gpio/consumer.h | 6 ++++++ 2 files changed, 19 insertions(+) (limited to 'include/linux/gpio/consumer.h') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index eb80dac4e26a..c952ef1b2f46 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -3264,8 +3264,21 @@ int gpiod_configure_flags(struct gpio_desc *desc, const char *con_id, if (lflags & GPIO_ACTIVE_LOW) set_bit(FLAG_ACTIVE_LOW, &desc->flags); + if (lflags & GPIO_OPEN_DRAIN) set_bit(FLAG_OPEN_DRAIN, &desc->flags); + else if (dflags & GPIOD_FLAGS_BIT_OPEN_DRAIN) { + /* + * This enforces open drain mode from the consumer side. + * This is necessary for some busses like I2C, but the lookup + * should *REALLY* have specified them as open drain in the + * first place, so print a little warning here. + */ + set_bit(FLAG_OPEN_DRAIN, &desc->flags); + gpiod_warn(desc, + "enforced open drain please flag it properly in DT/ACPI DSDT/board file\n"); + } + if (lflags & GPIO_OPEN_SOURCE) set_bit(FLAG_OPEN_SOURCE, &desc->flags); if (lflags & GPIO_SLEEP_MAY_LOOSE_VALUE) diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index 8f702fcbe485..5f72a49d1aa3 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -28,6 +28,7 @@ struct gpio_descs { #define GPIOD_FLAGS_BIT_DIR_SET BIT(0) #define GPIOD_FLAGS_BIT_DIR_OUT BIT(1) #define GPIOD_FLAGS_BIT_DIR_VAL BIT(2) +#define GPIOD_FLAGS_BIT_OPEN_DRAIN BIT(3) /** * Optional flags that can be passed to one of gpiod_* to configure direction @@ -39,6 +40,11 @@ enum gpiod_flags { GPIOD_OUT_LOW = GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT, GPIOD_OUT_HIGH = GPIOD_FLAGS_BIT_DIR_SET | GPIOD_FLAGS_BIT_DIR_OUT | GPIOD_FLAGS_BIT_DIR_VAL, + GPIOD_OUT_LOW_OPEN_DRAIN = GPIOD_FLAGS_BIT_DIR_SET | + GPIOD_FLAGS_BIT_DIR_OUT | GPIOD_FLAGS_BIT_OPEN_DRAIN, + GPIOD_OUT_HIGH_OPEN_DRAIN = GPIOD_FLAGS_BIT_DIR_SET | + GPIOD_FLAGS_BIT_DIR_OUT | GPIOD_FLAGS_BIT_DIR_VAL | + GPIOD_FLAGS_BIT_OPEN_DRAIN, }; #ifdef CONFIG_GPIOLIB -- cgit v1.2.3