General Purpose Input/Output (GPIO)¶

Contents:

Core¶

struct gpio_irq_chip: GPIO interrupt controller

Definition

struct gpio_irq_chip {
  struct irq_chip *chip;
  struct irq_domain *domain;
  const struct irq_domain_ops *domain_ops;
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY;
  struct fwnode_handle *fwnode;
  struct irq_domain *parent_domain;
  int (*child_to_parent_hwirq)(struct gpio_chip *gc,unsigned int child_hwirq,unsigned int child_type,unsigned int *parent_hwirq, unsigned int *parent_type);
  void *(*populate_parent_alloc_arg)(struct gpio_chip *gc,unsigned int parent_hwirq, unsigned int parent_type);
  unsigned int (*child_offset_to_irq)(struct gpio_chip *gc, unsigned int pin);
  struct irq_domain_ops child_irq_domain_ops;
#endif;
  irq_flow_handler_t handler;
  unsigned int default_type;
  struct lock_class_key *lock_key;
  struct lock_class_key *request_key;
  irq_flow_handler_t parent_handler;
  void *parent_handler_data;
  unsigned int num_parents;
  unsigned int *parents;
  unsigned int *map;
  bool threaded;
  int (*init_hw)(struct gpio_chip *gc);
  void (*init_valid_mask)(struct gpio_chip *gc,unsigned long *valid_mask, unsigned int ngpios);
  unsigned long *valid_mask;
  unsigned int first;
  void (*irq_enable)(struct irq_data *data);
  void (*irq_disable)(struct irq_data *data);
};

Members

chip

GPIO IRQ chip implementation, provided by GPIO driver.

domain

Interrupt translation domain; responsible for mapping between GPIO hwirq number and Linux IRQ number.

domain_ops

Table of interrupt domain operations for this IRQ chip.

fwnode

Firmware node corresponding to this gpiochip/irqchip, necessary for hierarchical irqdomain support.

parent_domain

If non-NULL, will be set as the parent of this GPIO interrupt controller’s IRQ domain to establish a hierarchical interrupt domain. The presence of this will activate the hierarchical interrupt support.

child_to_parent_hwirq

This callback translates a child hardware IRQ offset to a parent hardware IRQ offset on a hierarchical interrupt chip. The child hardware IRQs correspond to the GPIO index 0..ngpio-1 (see the ngpio field of struct gpio_chip) and the corresponding parent hardware IRQ and type (such as IRQ_TYPE_*) shall be returned by the driver. The driver can calculate this from an offset or using a lookup table or whatever method is best for this chip. Return 0 on successful translation in the driver.

If some ranges of hardware IRQs do not have a corresponding parent HWIRQ, return -EINVAL, but also make sure to fill in valid_mask and need_valid_mask to make these GPIO lines unavailable for translation.

populate_parent_alloc_arg

This optional callback allocates and populates the specific struct for the parent’s IRQ domain. If this is not specified, then gpiochip_populate_parent_fwspec_twocell will be used. A four-cell variant named gpiochip_populate_parent_fwspec_fourcell is also available.

child_offset_to_irq

This optional callback is used to translate the child’s GPIO line offset on the GPIO chip to an IRQ number for the GPIO to_irq() callback. If this is not specified, then a default callback will be provided that returns the line offset.

child_irq_domain_ops

The IRQ domain operations that will be used for this GPIO IRQ chip. If no operations are provided, then default callbacks will be populated to setup the IRQ hierarchy. Some drivers need to supply their own translate function.

handler

The IRQ handler to use (often a predefined IRQ core function) for GPIO IRQs, provided by GPIO driver.

default_type

Default IRQ triggering type applied during GPIO driver initialization, provided by GPIO driver.

lock_key

Per GPIO IRQ chip lockdep class for IRQ lock.

request_key

Per GPIO IRQ chip lockdep class for IRQ request.

parent_handler

The interrupt handler for the GPIO chip’s parent interrupts, may be NULL if the parent interrupts are nested rather than cascaded.

parent_handler_data

Data associated, and passed to, the handler for the parent interrupt.

num_parents

The number of interrupt parents of a GPIO chip.

parents

A list of interrupt parents of a GPIO chip. This is owned by the driver, so the core will only reference this list, not modify it.

map

A list of interrupt parents for each line of a GPIO chip.

threaded

True if set the interrupt handling uses nested threads.

init_hw

optional routine to initialize hardware before an IRQ chip will be added. This is quite useful when a particular driver wants to clear IRQ related registers in order to avoid undesired events.

init_valid_mask

optional routine to initialize valid_mask, to be used if not all GPIO lines are valid interrupts. Sometimes some lines just cannot fire interrupts, and this routine, when defined, is passed a bitmap in “valid_mask” and it will have ngpios bits from 0..(ngpios-1) set to “1” as in valid. The callback can then directly set some bits to “0” if they cannot be used for interrupts.

valid_mask

If not NULL holds bitmask of GPIOs which are valid to be included in IRQ domain of the chip.

first

Required for static IRQ allocation. If set, irq_domain_add_simple() will allocate and map all IRQs during initialization.

irq_enable

Store old irq_chip irq_enable callback

irq_disable

Store old irq_chip irq_disable callback

struct gpio_chip: abstract a GPIO controller

Definition

struct gpio_chip {
  const char              *label;
  struct gpio_device      *gpiodev;
  struct device           *parent;
  struct module           *owner;
  int (*request)(struct gpio_chip *gc, unsigned offset);
  void (*free)(struct gpio_chip *gc, unsigned offset);
  int (*get_direction)(struct gpio_chip *gc, unsigned offset);
  int (*direction_input)(struct gpio_chip *gc, unsigned offset);
  int (*direction_output)(struct gpio_chip *gc, unsigned offset, int value);
  int (*get)(struct gpio_chip *gc, unsigned offset);
  int (*get_multiple)(struct gpio_chip *gc,unsigned long *mask, unsigned long *bits);
  void (*set)(struct gpio_chip *gc, unsigned offset, int value);
  void (*set_multiple)(struct gpio_chip *gc,unsigned long *mask, unsigned long *bits);
  int (*set_config)(struct gpio_chip *gc,unsigned offset, unsigned long config);
  int (*to_irq)(struct gpio_chip *gc, unsigned offset);
  void (*dbg_show)(struct seq_file *s, struct gpio_chip *gc);
  int (*init_valid_mask)(struct gpio_chip *gc,unsigned long *valid_mask, unsigned int ngpios);
  int (*add_pin_ranges)(struct gpio_chip *gc);
  int base;
  u16 ngpio;
  const char              *const *names;
  bool can_sleep;
#if IS_ENABLED(CONFIG_GPIO_GENERIC);
  unsigned long (*read_reg)(void __iomem *reg);
  void (*write_reg)(void __iomem *reg, unsigned long data);
  bool be_bits;
  void __iomem *reg_dat;
  void __iomem *reg_set;
  void __iomem *reg_clr;
  void __iomem *reg_dir_out;
  void __iomem *reg_dir_in;
  bool bgpio_dir_unreadable;
  int bgpio_bits;
  spinlock_t bgpio_lock;
  unsigned long bgpio_data;
  unsigned long bgpio_dir;
#endif ;
#ifdef CONFIG_GPIOLIB_IRQCHIP;
  struct gpio_irq_chip irq;
#endif ;
  unsigned long *valid_mask;
#if defined(CONFIG_OF_GPIO);
  struct device_node *of_node;
  unsigned int of_gpio_n_cells;
  int (*of_xlate)(struct gpio_chip *gc, const struct of_phandle_args *gpiospec, u32 *flags);
#endif ;
};

Members

label: a functional name for the GPIO device, such as a part number or the name of the SoC IP-block implementing it.
gpiodev: the internal state holder, opaque struct
parent: optional parent device providing the GPIOs
owner: helps prevent removal of modules exporting active GPIOs
request: optional hook for chip-specific activation, such as enabling module power and clock; may sleep
free: optional hook for chip-specific deactivation, such as disabling module power and clock; may sleep
get_direction: returns direction for signal “offset”, 0=out, 1=in, (same as GPIOF_DIR_XXX), or negative error. It is recommended to always implement this function, even on input-only or output-only gpio chips.
direction_input: configures signal “offset” as input, or returns error This can be omitted on input-only or output-only gpio chips.
direction_output: configures signal “offset” as output, or returns error This can be omitted on input-only or output-only gpio chips.
get: returns value for signal “offset”, 0=low, 1=high, or negative error
get_multiple: reads values for multiple signals defined by “mask” and stores them in “bits”, returns 0 on success or negative error
set: assigns output value for signal “offset”
set_multiple: assigns output values for multiple signals defined by “mask”
set_config: optional hook for all kinds of settings. Uses the same packed config format as generic pinconf.
to_irq: optional hook supporting non-static gpio_to_irq() mappings; implementation may not sleep
dbg_show: optional routine to show contents in debugfs; default code will be used when this is omitted, but custom code can show extra state (such as pullup/pulldown configuration).
init_valid_mask: optional routine to initialize valid_mask, to be used if not all GPIOs are valid.
add_pin_ranges: optional routine to initialize pin ranges, to be used when requires special mapping of the pins that provides GPIO functionality. It is called after adding GPIO chip and before adding IRQ chip.
base: identifies the first GPIO number handled by this chip; or, if negative during registration, requests dynamic ID allocation. DEPRECATION: providing anything non-negative and nailing the base offset of GPIO chips is deprecated. Please pass -1 as base to let gpiolib select the chip base in all possible cases. We want to get rid of the static GPIO number space in the long run.
ngpio: the number of GPIOs handled by this controller; the last GPIO handled is (base + ngpio - 1).
names: if set, must be an array of strings to use as alternative names for the GPIOs in this chip. Any entry in the array may be NULL if there is no alias for the GPIO, however the array must be ngpio entries long. A name can include a single printk format specifier for an unsigned int. It is substituted by the actual number of the gpio.
can_sleep: flag must be set iff get()/set() methods sleep, as they must while accessing GPIO expander chips over I2C or SPI. This implies that if the chip supports IRQs, these IRQs need to be threaded as the chip access may sleep when e.g. reading out the IRQ status registers.
read_reg: reader function for generic GPIO
write_reg: writer function for generic GPIO
be_bits: if the generic GPIO has big endian bit order (bit 31 is representing line 0, bit 30 is line 1 … bit 0 is line 31) this is set to true by the generic GPIO core. It is for internal housekeeping only.
reg_dat: data (in) register for generic GPIO
reg_set: output set register (out=high) for generic GPIO
reg_clr: output clear register (out=low) for generic GPIO
reg_dir_out: direction out setting register for generic GPIO
reg_dir_in: direction in setting register for generic GPIO
bgpio_dir_unreadable: indicates that the direction register(s) cannot be read and we need to rely on out internal state tracking.
bgpio_bits: number of register bits used for a generic GPIO i.e. <register width> * 8
bgpio_lock: used to lock chip->bgpio_data. Also, this is needed to keep shadowed and real data registers writes together.
bgpio_data: shadowed data register for generic GPIO to clear/set bits safely.
bgpio_dir: shadowed direction register for generic GPIO to clear/set direction safely. A “1” in this word means the line is set as output.
irq: Integrates interrupt chip functionality with the GPIO chip. Can be used to handle IRQs for most practical cases.
valid_mask: If not NULL holds bitmask of GPIOs which are valid to be used from the chip.
of_node: Pointer to a device tree node representing this GPIO controller.
of_gpio_n_cells: Number of cells used to form the GPIO specifier.
of_xlate: Callback to translate a device tree GPIO specifier into a chip- relative GPIO number and flags.

Description

A gpio_chip can help platforms abstract various sources of GPIOs so they can all be accessed through a common programing interface. Example sources would be SOC controllers, FPGAs, multifunction chips, dedicated GPIO expanders, and so on.

Each chip controls a number of signals, identified in method calls by “offset” values in the range 0..(ngpio - 1). When those signals are referenced through calls like gpio_get_value(gpio), the offset is calculated by subtracting base from the gpio number.

gpiochip_add_data ( gc, data): register a gpio_chip

Parameters

gc: undescribed
data: driver-private data associated with this chip

Context

potentially before irqs will work

Description

When gpiochip_add_data() is called very early during boot, so that GPIOs can be freely used, the chip->parent device must be registered before the gpio framework’s arch_initcall(). Otherwise sysfs initialization for GPIOs will fail rudely.

gpiochip_add_data() must only be called after gpiolib initialization, ie after core_initcall().

If chip->base is negative, this requests dynamic assignment of a range of valid GPIOs.

Return

A negative errno if the chip can’t be registered, such as because the chip->base is invalid or already associated with a different chip. Otherwise it returns zero as a success code.

struct gpio_pin_range: pin range controlled by a gpio chip

Definition

struct gpio_pin_range {
  struct list_head node;
  struct pinctrl_dev *pctldev;
  struct pinctrl_gpio_range range;
};

Members

node: list for maintaining set of pin ranges, used internally
pctldev: pinctrl device which handles corresponding pins
range: actual range of pins controlled by a gpio controller

struct gpio_desc *gpio_to_desc(unsigned gpio)¶: Convert a GPIO number to its descriptor

Parameters

unsigned gpio: global GPIO number

Return

The GPIO descriptor associated with the given GPIO, or NULL if no GPIO with the given number exists in the system.

struct gpio_desc *gpiochip_get_desc(struct gpio_chip *gc, unsigned int hwnum)¶: get the GPIO descriptor corresponding to the given hardware number for this chip

Parameters

struct gpio_chip * gc: GPIO chip
unsigned int hwnum: hardware number of the GPIO for this chip

Return

A pointer to the GPIO descriptor or ERR_PTR(-EINVAL) if no GPIO exists in the given chip for the specified hardware number.

int desc_to_gpio(const struct gpio_desc *desc)¶: convert a GPIO descriptor to the integer namespace

Parameters

const struct gpio_desc * desc: GPIO descriptor

Description

This should disappear in the future but is needed since we still use GPIO numbers for error messages and sysfs nodes.

Return

The global GPIO number for the GPIO specified by its descriptor.

struct gpio_chip *gpiod_to_chip(const struct gpio_desc *desc)¶: Return the GPIO chip to which a GPIO descriptor belongs

Parameters

const struct gpio_desc * desc: descriptor to return the chip of

int gpiod_get_direction(struct gpio_desc *desc)¶: return the current direction of a GPIO

Parameters

struct gpio_desc * desc: GPIO to get the direction of

Description

Returns 0 for output, 1 for input, or an error code in case of error.

This function may sleep if gpiod_cansleep() is true.

void *gpiochip_get_data(struct gpio_chip *gc)¶: get per-subdriver data for the chip

Parameters

struct gpio_chip * gc: GPIO chip

Return

The per-subdriver data for the chip.

void gpiochip_remove(struct gpio_chip *gc)¶: unregister a gpio_chip

Parameters

struct gpio_chip * gc: the chip to unregister

Description

A gpio_chip with any GPIOs still requested may not be removed.

struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, void *data))¶: iterator for locating a specific gpio_chip

Parameters

void * data: data to pass to match function
int (*)(struct gpio_chip *gc, void *data) match: Callback function to check gpio_chip

Description

Similar to bus_find_device. It returns a reference to a gpio_chip as determined by a user supplied match callback. The callback should return 0 if the device doesn’t match and non-zero if it does. If the callback is non-zero, this function will return to the caller and not iterate over any more gpio_chips.

void gpiochip_set_nested_irqchip(struct gpio_chip *gc, struct irq_chip *irqchip, unsigned int parent_irq)¶: connects a nested irqchip to a gpiochip

Parameters

struct gpio_chip * gc: the gpiochip to set the irqchip nested handler to
struct irq_chip * irqchip: the irqchip to nest to the gpiochip
unsigned int parent_irq: the irq number corresponding to the parent IRQ for this nested irqchip

int gpiochip_irq_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hwirq)¶: maps an IRQ into a GPIO irqchip

Parameters

struct irq_domain * d: the irqdomain used by this irqchip
unsigned int irq: the global irq number used by this GPIO irqchip irq
irq_hw_number_t hwirq: the local IRQ/GPIO line offset on this gpiochip

Description

This function will set up the mapping for a certain IRQ line on a gpiochip by assigning the gpiochip as chip data, and using the irqchip stored inside the gpiochip.

int gpiochip_irq_domain_activate(struct irq_domain *domain, struct irq_data *data, bool reserve)¶: Lock a GPIO to be used as an IRQ

Parameters

struct irq_domain * domain: The IRQ domain used by this IRQ chip
struct irq_data * data: Outermost irq_data associated with the IRQ
bool reserve: If set, only reserve an interrupt vector instead of assigning one

Description

This function is a wrapper that calls gpiochip_lock_as_irq() and is to be used as the activate function for the struct irq_domain_ops. The host_data for the IRQ domain must be the struct gpio_chip.

void gpiochip_irq_domain_deactivate(struct irq_domain *domain, struct irq_data *data)¶: Unlock a GPIO used as an IRQ

Parameters

struct irq_domain * domain: The IRQ domain used by this IRQ chip
struct irq_data * data: Outermost irq_data associated with the IRQ

Description

This function is a wrapper that will call gpiochip_unlock_as_irq() and is to be used as the deactivate function for the struct irq_domain_ops. The host_data for the IRQ domain must be the struct gpio_chip.

int gpiochip_irqchip_add_key(struct gpio_chip *gc, struct irq_chip *irqchip, unsigned int first_irq, irq_flow_handler_t handler, unsigned int type, bool threaded, struct lock_class_key *lock_key, struct lock_class_key *request_key)¶: adds an irqchip to a gpiochip

Parameters

struct gpio_chip * gc: the gpiochip to add the irqchip to
struct irq_chip * irqchip: the irqchip to add to the gpiochip
unsigned int first_irq: if not dynamically assigned, the base (first) IRQ to allocate gpiochip irqs from
irq_flow_handler_t handler: the irq handler to use (often a predefined irq core function)
unsigned int type: the default type for IRQs on this irqchip, pass IRQ_TYPE_NONE to have the core avoid setting up any default type in the hardware.
bool threaded: whether this irqchip uses a nested thread handler
struct lock_class_key * lock_key: lockdep class for IRQ lock
struct lock_class_key * request_key: lockdep class for IRQ request

Description

This function closely associates a certain irqchip with a certain gpiochip, providing an irq domain to translate the local IRQs to global irqs in the gpiolib core, and making sure that the gpiochip is passed as chip data to all related functions. Driver callbacks need to use gpiochip_get_data() to get their local state containers back from the gpiochip passed as chip data. An irqdomain will be stored in the gpiochip that shall be used by the driver to handle IRQ number translation. The gpiochip will need to be initialized and registered before calling this function.

This function will handle two cell:ed simple IRQs and assumes all the pins on the gpiochip can generate a unique IRQ. Everything else need to be open coded.

int gpiochip_generic_request(struct gpio_chip *gc, unsigned offset)¶: request the gpio function for a pin

Parameters

struct gpio_chip * gc: the gpiochip owning the GPIO
unsigned offset: the offset of the GPIO to request for GPIO function

void gpiochip_generic_free(struct gpio_chip *gc, unsigned offset)¶: free the gpio function from a pin

Parameters

struct gpio_chip * gc: the gpiochip to request the gpio function for
unsigned offset: the offset of the GPIO to free from GPIO function

int gpiochip_generic_config(struct gpio_chip *gc, unsigned offset, unsigned long config)¶: apply configuration for a pin

Parameters

struct gpio_chip * gc: the gpiochip owning the GPIO
unsigned offset: the offset of the GPIO to apply the configuration
unsigned long config: the configuration to be applied

int gpiochip_add_pingroup_range(struct gpio_chip *gc, struct pinctrl_dev *pctldev, unsigned int gpio_offset, const char *pin_group)¶: add a range for GPIO <-> pin mapping

Parameters

struct gpio_chip * gc: the gpiochip to add the range for
struct pinctrl_dev * pctldev: the pin controller to map to
unsigned int gpio_offset: the start offset in the current gpio_chip number space
const char * pin_group: name of the pin group inside the pin controller

Description

Calling this function directly from a DeviceTree-supported pinctrl driver is DEPRECATED. Please see Section 2.1 of Documentation/devicetree/bindings/gpio/gpio.txt on how to bind pinctrl and gpio drivers via the “gpio-ranges” property.

int gpiochip_add_pin_range(struct gpio_chip *gc, const char *pinctl_name, unsigned int gpio_offset, unsigned int pin_offset, unsigned int npins)¶: add a range for GPIO <-> pin mapping

Parameters

struct gpio_chip * gc: the gpiochip to add the range for
const char * pinctl_name: the dev_name() of the pin controller to map to
unsigned int gpio_offset: the start offset in the current gpio_chip number space
unsigned int pin_offset: the start offset in the pin controller number space
unsigned int npins: the number of pins from the offset of each pin space (GPIO and pin controller) to accumulate in this range

Return

0 on success, or a negative error-code on failure.

Calling this function directly from a DeviceTree-supported pinctrl driver is DEPRECATED. Please see Section 2.1 of Documentation/devicetree/bindings/gpio/gpio.txt on how to bind pinctrl and gpio drivers via the “gpio-ranges” property.

void gpiochip_remove_pin_ranges(struct gpio_chip *gc)¶: remove all the GPIO <-> pin mappings

Parameters

struct gpio_chip * gc: the chip to remove all the mappings for

const char *gpiochip_is_requested(struct gpio_chip *gc, unsigned offset)¶: return string iff signal was requested

Parameters

struct gpio_chip * gc: controller managing the signal
unsigned offset: of signal within controller’s 0..(ngpio - 1) range

Description

Returns NULL if the GPIO is not currently requested, else a string. The string returned is the label passed to gpio_request(); if none has been passed it is a meaningless, non-NULL constant.

This function is for use by GPIO controller drivers. The label can help with diagnostics, and knowing that the signal is used as a GPIO can help avoid accidentally multiplexing it to another controller.

struct gpio_desc *gpiochip_request_own_desc(struct gpio_chip *gc, unsigned int hwnum, const char *label, enum gpio_lookup_flags lflags, enum gpiod_flags dflags)¶: Allow GPIO chip to request its own descriptor

Parameters

struct gpio_chip * gc: GPIO chip
unsigned int hwnum: hardware number of the GPIO for which to request the descriptor
const char * label: label for the GPIO
enum gpio_lookup_flags lflags: lookup flags for this GPIO or 0 if default, this can be used to specify things like line inversion semantics with the machine flags such as GPIO_OUT_LOW
enum gpiod_flags dflags: descriptor request flags for this GPIO or 0 if default, this can be used to specify consumer semantics such as open drain

Description

Function allows GPIO chip drivers to request and use their own GPIO descriptors via gpiolib API. Difference to gpiod_request() is that this function will not increase reference count of the GPIO chip module. This allows the GPIO chip module to be unloaded as needed (we assume that the GPIO chip driver handles freeing the GPIOs it has requested).

Return

A pointer to the GPIO descriptor, or an ERR_PTR()-encoded negative error code on failure.

void gpiochip_free_own_desc(struct gpio_desc *desc)¶: Free GPIO requested by the chip driver

Parameters

struct gpio_desc * desc: GPIO descriptor to free

Description

Function frees the given GPIO requested previously with gpiochip_request_own_desc().

int gpiod_direction_input(struct gpio_desc *desc)¶: set the GPIO direction to input

Parameters

struct gpio_desc * desc: GPIO to set to input

Description

Set the direction of the passed GPIO to input, such as gpiod_get_value() can be called safely on it.

Return 0 in case of success, else an error code.

int gpiod_direction_output_raw(struct gpio_desc *desc, int value)¶: set the GPIO direction to output

Parameters

struct gpio_desc * desc: GPIO to set to output
int value: initial output value of the GPIO

Description

Set the direction of the passed GPIO to output, such as gpiod_set_value() can be called safely on it. The initial value of the output must be specified as raw value on the physical line without regard for the ACTIVE_LOW status.

Return 0 in case of success, else an error code.

int gpiod_direction_output(struct gpio_desc *desc, int value)¶: set the GPIO direction to output

Parameters

struct gpio_desc * desc: GPIO to set to output
int value: initial output value of the GPIO

Description

Set the direction of the passed GPIO to output, such as gpiod_set_value() can be called safely on it. The initial value of the output must be specified as the logical value of the GPIO, i.e. taking its ACTIVE_LOW status into account.

Return 0 in case of success, else an error code.

int gpiod_set_config(struct gpio_desc *desc, unsigned long config)¶: sets config for a GPIO

Parameters

struct gpio_desc * desc: descriptor of the GPIO for which to set the configuration
unsigned long config: Same packed config format as generic pinconf

Return

0 on success, -ENOTSUPP if the controller doesn’t support setting the configuration.

int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce)¶: sets debounce time for a GPIO

Parameters

struct gpio_desc * desc: descriptor of the GPIO for which to set debounce time
unsigned debounce: debounce time in microseconds

Return

0 on success, -ENOTSUPP if the controller doesn’t support setting the debounce time.

int gpiod_set_transitory(struct gpio_desc *desc, bool transitory)¶: Lose or retain GPIO state on suspend or reset

Parameters

struct gpio_desc * desc: descriptor of the GPIO for which to configure persistence
bool transitory: True to lose state on suspend or reset, false for persistence

Return

0 on success, otherwise a negative error code.

int gpiod_is_active_low(const struct gpio_desc *desc)¶: test whether a GPIO is active-low or not

Parameters

const struct gpio_desc * desc: the gpio descriptor to test

Description

Returns 1 if the GPIO is active-low, 0 otherwise.

void gpiod_toggle_active_low(struct gpio_desc *desc)¶: toggle whether a GPIO is active-low or not

Parameters

struct gpio_desc * desc: the gpio descriptor to change

int gpiod_get_raw_value(const struct gpio_desc *desc)¶: return a gpio’s raw value

Parameters

const struct gpio_desc * desc: gpio whose value will be returned

Description

Return the GPIO’s raw value, i.e. the value of the physical line disregarding its ACTIVE_LOW status, or negative errno on failure.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

int gpiod_get_value(const struct gpio_desc *desc)¶: return a gpio’s value

Parameters

const struct gpio_desc * desc: gpio whose value will be returned

Description

Return the GPIO’s logical value, i.e. taking the ACTIVE_LOW status into account, or negative errno on failure.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

int gpiod_get_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, struct gpio_array *array_info, unsigned long *value_bitmap)¶: read raw values from an array of GPIOs

Parameters

unsigned int array_size: number of elements in the descriptor array / value bitmap
struct gpio_desc ** desc_array: array of GPIO descriptors whose values will be read
struct gpio_array * array_info: information on applicability of fast bitmap processing path
unsigned long * value_bitmap: bitmap to store the read values

Description

Read the raw values of the GPIOs, i.e. the values of the physical lines without regard for their ACTIVE_LOW status. Return 0 in case of success, else an error code.

This function can be called from contexts where we cannot sleep, and it will complain if the GPIO chip functions potentially sleep.

int gpiod_get_array_value(unsigned int array_size, struct gpio_desc **desc_array, struct gpio_array *array_info, unsigned long *value_bitmap)¶: read values from an array of GPIOs

Parameters

unsigned int array_size: number of elements in the descriptor array / value bitmap
struct gpio_desc ** desc_array: array of GPIO descriptors whose values will be read
struct gpio_array * array_info: information on applicability of fast bitmap processing path
unsigned long * value_bitmap: bitmap to store the read values

Description

Read the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status into account. Return 0 in case of success, else an error code.

This function can be called from contexts where we cannot sleep, and it will complain if the GPIO chip functions potentially sleep.

void gpiod_set_raw_value(struct gpio_desc *desc, int value)¶: assign a gpio’s raw value

Parameters

struct gpio_desc * desc: gpio whose value will be assigned
int value: value to assign

Description

Set the raw value of the GPIO, i.e. the value of its physical line without regard for its ACTIVE_LOW status.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

void gpiod_set_value(struct gpio_desc *desc, int value)¶: assign a gpio’s value

Parameters

struct gpio_desc * desc: gpio whose value will be assigned
int value: value to assign

Description

Set the logical value of the GPIO, i.e. taking its ACTIVE_LOW, OPEN_DRAIN and OPEN_SOURCE flags into account.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

int gpiod_set_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, struct gpio_array *array_info, unsigned long *value_bitmap)¶: assign values to an array of GPIOs

Parameters

unsigned int array_size: number of elements in the descriptor array / value bitmap
struct gpio_desc ** desc_array: array of GPIO descriptors whose values will be assigned
struct gpio_array * array_info: information on applicability of fast bitmap processing path
unsigned long * value_bitmap: bitmap of values to assign

Description

Set the raw values of the GPIOs, i.e. the values of the physical lines without regard for their ACTIVE_LOW status.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

int gpiod_set_array_value(unsigned int array_size, struct gpio_desc **desc_array, struct gpio_array *array_info, unsigned long *value_bitmap)¶: assign values to an array of GPIOs

Parameters

unsigned int array_size: number of elements in the descriptor array / value bitmap
struct gpio_desc ** desc_array: array of GPIO descriptors whose values will be assigned
struct gpio_array * array_info: information on applicability of fast bitmap processing path
unsigned long * value_bitmap: bitmap of values to assign

Description

Set the logical values of the GPIOs, i.e. taking their ACTIVE_LOW status into account.

This function can be called from contexts where we cannot sleep, and will complain if the GPIO chip functions potentially sleep.

int gpiod_cansleep(const struct gpio_desc *desc)¶: report whether gpio value access may sleep

Parameters

const struct gpio_desc * desc: gpio to check

int gpiod_set_consumer_name(struct gpio_desc *desc, const char *name)¶: set the consumer name for the descriptor

Parameters

struct gpio_desc * desc: gpio to set the consumer name on
const char * name: the new consumer name

int gpiod_to_irq(const struct gpio_desc *desc)¶: return the IRQ corresponding to a GPIO

Parameters

const struct gpio_desc * desc: gpio whose IRQ will be returned (already requested)

Description

Return the IRQ corresponding to the passed GPIO, or an error code in case of error.

int gpiochip_lock_as_irq(struct gpio_chip *gc, unsigned int offset)¶: lock a GPIO to be used as IRQ

Parameters

struct gpio_chip * gc: the chip the GPIO to lock belongs to
unsigned int offset: the offset of the GPIO to lock as IRQ

Description

This is used directly by GPIO drivers that want to lock down a certain GPIO line to be used for IRQs.

void gpiochip_unlock_as_irq(struct gpio_chip *gc, unsigned int offset)¶: unlock a GPIO used as IRQ

Parameters

struct gpio_chip * gc: the chip the GPIO to lock belongs to
unsigned int offset: the offset of the GPIO to lock as IRQ

Description

This is used directly by GPIO drivers that want to indicate that a certain GPIO is no longer used exclusively for IRQ.

int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc)¶: return a gpio’s raw value

Parameters

const struct gpio_desc * desc: gpio whose value will be returned

Description

Return the GPIO’s raw value, i.e. the value of the physical line disregarding its ACTIVE_LOW status, or negative errno on failure.