Introduce new functions gpiod_set_array & gpiod_set_raw_array to the consumer interface which allow setting multiple outputs with just one function call. Also add an optional set_multiple function to the driver interface. Without an implementation of that function in the chip driver outputs are set sequentially.
Implementing the set_multiple function in a chip driver allows for: - Improved performance for certain use cases. The original motivation for this was the task of configuring an FPGA. In that specific case, where 9 GPIO lines have to be set many times, configuration time goes down from 48 s to 20 s when using the new function. - Simultaneous glitch-free setting of multiple pins on any kind of parallel bus attached to GPIOs provided they all reside on the same chip and bank. Limitations: Performance is only improved for normal high-low outputs. Open drain and open source outputs are always set separately from each other. Those kinds of outputs could probably be accelerated in a similar way if we could forgo the error checking when setting GPIO directions. Signed-off-by: Rojhalat Ibrahim <[email protected]> --- Change log: v4: - add gpiod_set_array function for setting logical values - change interface of the set_multiple driver function to use unsigned long as type for the bit fields - use generic bitops (which also use unsigned long for bit fields) - do not use ARCH_NR_GPIOS any more v3: - add documentation - change commit message v2: - use descriptor interface - allow arbitrary groups of GPIOs spanning multiple chips Documentation/gpio/consumer.txt | 23 +++++ drivers/gpio/gpiolib.c | 180 ++++++++++++++++++++++++++++++++++++++++ include/linux/gpio/consumer.h | 38 +++++++++ include/linux/gpio/driver.h | 4 + 4 files changed, 245 insertions(+) diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt index 09854fe..ba02b84 100644 --- a/Documentation/gpio/consumer.txt +++ b/Documentation/gpio/consumer.txt @@ -163,6 +163,29 @@ The active-low state of a GPIO can also be queried using the following call: Note that these functions should only be used with great moderation ; a driver should not have to care about the physical line level. +Set multiple GPIO outputs with a single function call +----------------------------------------------------- +The following functions set the output values of an array of GPIOs: + + void gpiod_set_array(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) + void gpiod_set_raw_array(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) + void gpiod_set_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) + void gpiod_set_raw_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) + +The array can be an arbitrary set of GPIOs. The functions will try to set +GPIOs belonging to the same bank or chip simultaneously if supported by the +corresponding chip driver. In that case a significantly improved performance +can be expected. If simultaneous setting is not possible the GPIOs will be set +sequentially. + GPIOs mapped to IRQs -------------------- GPIO lines can quite often be used as IRQs. You can get the IRQ number diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f48817d..a2be195 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2345,6 +2345,84 @@ static void _gpiod_set_raw_value(struct gpio_desc *desc, bool value) chip->set(chip, gpio_chip_hwgpio(desc), value); } +/* + * set multiple outputs on the same chip; + * use the chip's set_multiple function if available; + * otherwise set the outputs sequentially; + * @mask: bit mask array; one bit per output; BITS_PER_LONG bits per word + * defines which outputs are to be changed + * @bits: bit value array; one bit per output; BITS_PER_LONG bits per word + * defines the values the outputs specified by mask are to be set to + */ +static void gpio_chip_set_multiple(struct gpio_chip *chip, + unsigned long *mask, unsigned long *bits) +{ + if (chip->set_multiple) { + chip->set_multiple(chip, mask, bits); + } else { + int i; + for (i = 0; i < chip->ngpio; i++) { + if (mask[BIT_WORD(i)] == 0) { + /* no more set bits in this mask word; + * skip ahead to the next word */ + i = (BIT_WORD(i) + 1) * BITS_PER_LONG - 1; + continue; + } + /* set outputs if the corresponding mask bit is set */ + if (__test_and_clear_bit(i, mask)) { + chip->set(chip, i, test_bit(i, bits)); + } + } + } +} + +static void gpiod_set_array_priv(bool raw, unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + int i = 0; + + while (i < array_size) { + struct gpio_chip *chip = desc_array[i]->chip; + unsigned long mask[BITS_TO_LONGS(chip->ngpio)]; + unsigned long bits[BITS_TO_LONGS(chip->ngpio)]; + int count = 0; + + memset(mask, 0, sizeof(mask)); + do { + struct gpio_desc *desc = desc_array[i]; + int hwgpio = gpio_chip_hwgpio(desc); + int value = value_array[i]; + + if (!raw && test_bit(FLAG_ACTIVE_LOW, &desc->flags)) + value = !value; + trace_gpio_value(desc_to_gpio(desc), 0, value); + /* + * collect all normal outputs belonging to the same chip + * open drain and open source outputs are set individually + */ + if (test_bit(FLAG_OPEN_DRAIN, &desc->flags)) { + _gpio_set_open_drain_value(desc,value); + } else if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) { + _gpio_set_open_source_value(desc, value); + } else { + __set_bit(hwgpio, mask); + if (value) { + __set_bit(hwgpio, bits); + } else { + __clear_bit(hwgpio, bits); + } + count++; + } + i++; + } while ((i < array_size) && (desc_array[i]->chip == chip)); + /* push collected bits to outputs */ + if (count != 0) { + gpio_chip_set_multiple(chip, mask, bits); + } + } +} + /** * gpiod_set_raw_value() - assign a gpio's raw value * @desc: gpio whose value will be assigned @@ -2390,6 +2468,60 @@ void gpiod_set_value(struct gpio_desc *desc, int value) EXPORT_SYMBOL_GPL(gpiod_set_value); /** + * gpiod_set_raw_array() - assign values to an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be assigned + * @value_array: array of values to assign + * + * Set the raw values of the GPIOs, i.e. the values of the physical lines + * without regard for their ACTIVE_LOW status. + * + * This function should be called from contexts where we cannot sleep, and will + * complain if the GPIO chip functions potentially sleep. + */ +void gpiod_set_raw_array(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array) +{ + if (array_size == 0) + return; + if (!desc_array) + return; + if (!desc_array[0]) + return; + /* Should be using gpiod_set_raw_array_cansleep() */ + WARN_ON(desc_array[0]->chip->can_sleep); + gpiod_set_array_priv(true, array_size, desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_set_raw_array); + +/** + * gpiod_set_array() - assign values to an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be assigned + * @value_array: array of values to assign + * + * Set the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status + * into account. + * + * This function should be called from contexts where we cannot sleep, and will + * complain if the GPIO chip functions potentially sleep. + */ +void gpiod_set_array(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array) +{ + if (array_size == 0) + return; + if (!desc_array) + return; + if (!desc_array[0]) + return; + /* Should be using gpiod_set_array_cansleep() */ + WARN_ON(desc_array[0]->chip->can_sleep); + gpiod_set_array_priv(false, array_size, desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_set_array); + +/** * gpiod_cansleep() - report whether gpio value access may sleep * @desc: gpio to check * @@ -2559,6 +2691,54 @@ void gpiod_set_value_cansleep(struct gpio_desc *desc, int value) EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep); /** + * gpiod_set_raw_array_cansleep() - assign values to an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be assigned + * @value_array: array of values to assign + * + * Set the raw values of the GPIOs, i.e. the values of the physical lines + * without regard for their ACTIVE_LOW status. + * + * This function is to be called from contexts that can sleep. + */ +void gpiod_set_raw_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + might_sleep_if(extra_checks); + if (array_size == 0) + return; + if (!desc_array) + return; + gpiod_set_array_priv(true, array_size, desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_set_raw_array_cansleep); + +/** + * gpiod_set_array_cansleep() - assign values to an array of GPIOs + * @array_size: number of elements in the descriptor / value arrays + * @desc_array: array of GPIO descriptors whose values will be assigned + * @value_array: array of values to assign + * + * Set the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status + * into account. + * + * This function is to be called from contexts that can sleep. + */ +void gpiod_set_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + might_sleep_if(extra_checks); + if (array_size == 0) + return; + if (!desc_array) + return; + gpiod_set_array_priv(false, array_size, desc_array, value_array); +} +EXPORT_SYMBOL_GPL(gpiod_set_array_cansleep); + +/** * gpiod_add_lookup_table() - register GPIO device consumers * @table: table of consumers to register */ diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index bed128e..f87315a 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -40,14 +40,24 @@ 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); void gpiod_set_value(struct gpio_desc *desc, int value); +void gpiod_set_array(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array); int gpiod_get_raw_value(const struct gpio_desc *desc); void gpiod_set_raw_value(struct gpio_desc *desc, int value); +void gpiod_set_raw_array(unsigned int array_size, + struct gpio_desc **desc_array, int *value_array); /* Value get/set from sleeping context */ int gpiod_get_value_cansleep(const struct gpio_desc *desc); void gpiod_set_value_cansleep(struct gpio_desc *desc, int value); +void gpiod_set_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array); int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc); void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value); +void gpiod_set_raw_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array); int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce); @@ -139,6 +149,13 @@ static inline void gpiod_set_value(struct gpio_desc *desc, int value) /* GPIO can never have been requested */ WARN_ON(1); } +static inline void gpiod_set_array(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} static inline int gpiod_get_raw_value(const struct gpio_desc *desc) { /* GPIO can never have been requested */ @@ -150,6 +167,13 @@ static inline void gpiod_set_raw_value(struct gpio_desc *desc, int value) /* GPIO can never have been requested */ WARN_ON(1); } +static inline void gpiod_set_raw_array(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} static inline int gpiod_get_value_cansleep(const struct gpio_desc *desc) { @@ -162,6 +186,13 @@ static inline void gpiod_set_value_cansleep(struct gpio_desc *desc, int value) /* GPIO can never have been requested */ WARN_ON(1); } +static inline void gpiod_set_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} static inline int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc) { /* GPIO can never have been requested */ @@ -174,6 +205,13 @@ static inline void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, /* GPIO can never have been requested */ WARN_ON(1); } +static inline void gpiod_set_raw_array_cansleep(unsigned int array_size, + struct gpio_desc **desc_array, + int *value_array) +{ + /* GPIO can never have been requested */ + WARN_ON(1); +} static inline int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce) { diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index 1827b43..9e9ad1e 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -32,6 +32,7 @@ struct seq_file; * @get: returns value for signal "offset"; for output signals this * returns either the value actually sensed, or zero * @set: assigns output value for signal "offset" + * @set_multiple: assigns output values for multiple signals defined by "mask" * @set_debounce: optional hook for setting debounce time for specified gpio in * interrupt triggered gpio chips * @to_irq: optional hook supporting non-static gpio_to_irq() mappings; @@ -84,6 +85,9 @@ struct gpio_chip { unsigned offset); void (*set)(struct gpio_chip *chip, unsigned offset, int value); + void (*set_multiple)(struct gpio_chip *chip, + unsigned long *mask, + unsigned long *bits); int (*set_debounce)(struct gpio_chip *chip, unsigned offset, unsigned debounce); -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
