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;
  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 parent_irq;
  unsigned int *parents;
  unsigned int *map;
  bool threaded;
  bool need_valid_mask;
  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.
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.
parent_irq
For use by gpiochip_set_cascaded_irqchip()
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.
need_valid_mask
If set core allocates valid_mask with all bits set to one.
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 *chip, unsigned offset);
  void (*free)(struct gpio_chip *chip, unsigned offset);
  int (*get_direction)(struct gpio_chip *chip, unsigned offset);
  int (*direction_input)(struct gpio_chip *chip, unsigned offset);
  int (*direction_output)(struct gpio_chip *chip, unsigned offset, int value);
  int (*get)(struct gpio_chip *chip, unsigned offset);
  int (*get_multiple)(struct gpio_chip *chip,unsigned long *mask, unsigned long *bits);
  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_config)(struct gpio_chip *chip,unsigned offset, unsigned long config);
  int (*to_irq)(struct gpio_chip *chip, unsigned offset);
  void (*dbg_show)(struct seq_file *s, struct gpio_chip *chip);
  int (*init_valid_mask)(struct gpio_chip *chip);
  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;
  bool bgpio_dir_inverted;
  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;
  bool need_valid_mask;
  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).
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
direction setting register for generic GPIO
bgpio_dir_inverted
indicates that the direction register is inverted (gpiolib private state variable)
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.
irq
Integrates interrupt chip functionality with the GPIO chip. Can be used to handle IRQs for most practical cases.
need_valid_mask
If set core allocates valid_mask with all its values initialized with init_valid_mask() or set to one if init_valid_mask() is not defined
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(chip, data)

register a gpio_chip

Parameters

chip
the chip to register, with chip->base initialized
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.

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 * chip)

get per-subdriver data for the chip

Parameters

struct gpio_chip * chip
GPIO chip

Return

The per-subdriver data for the chip.

void gpiochip_remove(struct gpio_chip * chip)

unregister a gpio_chip

Parameters

struct gpio_chip * chip
the chip to unregister

Description

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

int devm_gpiochip_add_data(struct device * dev, struct gpio_chip * chip, void * data)

Resource manager gpiochip_add_data()

Parameters

struct device * dev
pointer to the device that gpio_chip belongs to.
struct gpio_chip * chip
the chip to register, with chip->base initialized
void * data
driver-private data associated with this chip

Context

potentially before irqs will work

Description

The gpio chip automatically be released when the device is unbound.

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.

void devm_gpiochip_remove(struct device * dev, struct gpio_chip * chip)

Resource manager of gpiochip_remove()

Parameters

struct device * dev
device for which which resource was allocated
struct gpio_chip * chip
the chip to remove

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 *chip, void *data)

iterator for locating a specific gpio_chip

Parameters

void * data
data to pass to match function
int (*)(struct gpio_chip *chip, 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_chained_irqchip(struct gpio_chip * gpiochip, struct irq_chip * irqchip, unsigned int parent_irq, irq_flow_handler_t parent_handler)

connects a chained irqchip to a gpiochip

Parameters

struct gpio_chip * gpiochip
the gpiochip to set the irqchip chain to
struct irq_chip * irqchip
the irqchip to chain to the gpiochip
unsigned int parent_irq
the irq number corresponding to the parent IRQ for this chained irqchip
irq_flow_handler_t parent_handler
the parent interrupt handler for the accumulated IRQ coming out of the gpiochip.
void gpiochip_set_nested_irqchip(struct gpio_chip * gpiochip, struct irq_chip * irqchip, unsigned int parent_irq)

connects a nested irqchip to a gpiochip

Parameters

struct gpio_chip * gpiochip
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_irqchip_add_key(struct gpio_chip * gpiochip, 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 * gpiochip
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 * chip, unsigned offset)

request the gpio function for a pin

Parameters

struct gpio_chip * chip
the gpiochip owning the GPIO
unsigned offset
the offset of the GPIO to request for GPIO function
void gpiochip_generic_free(struct gpio_chip * chip, unsigned offset)

free the gpio function from a pin

Parameters

struct gpio_chip * chip
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 * chip, unsigned offset, unsigned long config)

apply configuration for a pin

Parameters

struct gpio_chip * chip
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 * chip, struct pinctrl_dev * pctldev, unsigned int gpio_offset, const char * pin_group)

add a range for GPIO <-> pin mapping

Parameters

struct gpio_chip * chip
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 * chip, 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 * chip
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 * chip)

remove all the GPIO <-> pin mappings

Parameters

struct gpio_chip * chip
the chip to remove all the mappings for
const char * gpiochip_is_requested(struct gpio_chip * chip, unsigned offset)

return string iff signal was requested

Parameters

struct gpio_chip * chip
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 * chip, u16 hwnum, const char * label)

Allow GPIO chip to request its own descriptor

Parameters

struct gpio_chip * chip
GPIO chip
u16 hwnum
hardware number of the GPIO for which to request the descriptor
const char * label
label for the GPIO

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_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.

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 should 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 should 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 should 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 should 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 should 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 should 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 should 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 should 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
void 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 * chip, unsigned int offset)

lock a GPIO to be used as IRQ

Parameters

struct gpio_chip * chip
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 * chip, unsigned int offset)

unlock a GPIO used as IRQ

Parameters

struct gpio_chip * chip
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.

This function is to be called from contexts that can sleep.

int gpiod_get_value_cansleep(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 is to be called from contexts that can sleep.

int gpiod_get_raw_array_value_cansleep(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 is to be called from contexts that can sleep.

int gpiod_get_array_value_cansleep(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 is to be called from contexts that can sleep.

void gpiod_set_raw_value_cansleep(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 is to be called from contexts that can sleep.

void gpiod_set_value_cansleep(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 status into account

This function is to be called from contexts that can sleep.

int gpiod_set_raw_array_value_cansleep(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 is to be called from contexts that can sleep.

int gpiod_set_array_value_cansleep(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 is to be called from contexts that can sleep.

void gpiod_add_lookup_table(struct gpiod_lookup_table * table)

register GPIO device consumers

Parameters

struct gpiod_lookup_table * table
table of consumers to register
void gpiod_remove_lookup_table(struct gpiod_lookup_table * table)

unregister GPIO device consumers

Parameters

struct gpiod_lookup_table * table
table of consumers to unregister
void gpiod_add_hogs(struct gpiod_hog * hogs)

register a set of GPIO hogs from machine code

Parameters

struct gpiod_hog * hogs
table of gpio hog entries with a zeroed sentinel at the end
int gpiod_count(struct device * dev, const char * con_id)

return the number of GPIOs associated with a device / function or -ENOENT if no GPIO has been assigned to the requested function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
struct gpio_desc * gpiod_get(struct device * dev, const char * con_id, enum gpiod_flags flags)

obtain a GPIO for a given GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Return the GPIO descriptor corresponding to the function con_id of device dev, -ENOENT if no GPIO has been assigned to the requested function, or another IS_ERR() code if an error occurred while trying to acquire the GPIO.

struct gpio_desc * gpiod_get_optional(struct device * dev, const char * con_id, enum gpiod_flags flags)

obtain an optional GPIO for a given GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

This is equivalent to gpiod_get(), except that when no GPIO was assigned to the requested function it will return NULL. This is convenient for drivers that need to handle optional GPIOs.

struct gpio_desc * gpiod_get_index(struct device * dev, const char * con_id, unsigned int idx, enum gpiod_flags flags)

obtain a GPIO from a multi-index GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
unsigned int idx
index of the GPIO to obtain in the consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

This variant of gpiod_get() allows to access GPIOs other than the first defined one for functions that define several GPIOs.

Return a valid GPIO descriptor, -ENOENT if no GPIO has been assigned to the requested function and/or index, or another IS_ERR() code if an error occurred while trying to acquire the GPIO.

struct gpio_desc * gpiod_get_from_of_node(struct device_node * node, const char * propname, int index, enum gpiod_flags dflags, const char * label)

obtain a GPIO from an OF node

Parameters

struct device_node * node
handle of the OF node
const char * propname
name of the DT property representing the GPIO
int index
index of the GPIO to obtain for the consumer
enum gpiod_flags dflags
GPIO initialization flags
const char * label
label to attach to the requested GPIO

Return

On successful request the GPIO pin is configured in accordance with provided dflags. If the node does not have the requested GPIO property, NULL is returned.

In case of error an ERR_PTR() is returned.

struct gpio_desc * fwnode_get_named_gpiod(struct fwnode_handle * fwnode, const char * propname, int index, enum gpiod_flags dflags, const char * label)

obtain a GPIO from firmware node

Parameters

struct fwnode_handle * fwnode
handle of the firmware node
const char * propname
name of the firmware property representing the GPIO
int index
index of the GPIO to obtain for the consumer
enum gpiod_flags dflags
GPIO initialization flags
const char * label
label to attach to the requested GPIO

Description

This function can be used for drivers that get their configuration from opaque firmware.

The function properly finds the corresponding GPIO using whatever is the underlying firmware interface and then makes sure that the GPIO descriptor is requested before it is returned to the caller.

Return

On successful request the GPIO pin is configured in accordance with provided dflags.

In case of error an ERR_PTR() is returned.

struct gpio_desc * gpiod_get_index_optional(struct device * dev, const char * con_id, unsigned int index, enum gpiod_flags flags)

obtain an optional GPIO from a multi-index GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
unsigned int index
index of the GPIO to obtain in the consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

This is equivalent to gpiod_get_index(), except that when no GPIO with the specified index was assigned to the requested function it will return NULL. This is convenient for drivers that need to handle optional GPIOs.

struct gpio_descs * gpiod_get_array(struct device * dev, const char * con_id, enum gpiod_flags flags)

obtain multiple GPIOs from a multi-index GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

This function acquires all the GPIOs defined under a given function.

Return a struct gpio_descs containing an array of descriptors, -ENOENT if no GPIO has been assigned to the requested function, or another IS_ERR() code if an error occurred while trying to acquire the GPIOs.

struct gpio_descs * gpiod_get_array_optional(struct device * dev, const char * con_id, enum gpiod_flags flags)

obtain multiple GPIOs from a multi-index GPIO function

Parameters

struct device * dev
GPIO consumer, can be NULL for system-global GPIOs
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

This is equivalent to gpiod_get_array(), except that when no GPIO was assigned to the requested function it will return NULL.

void gpiod_put(struct gpio_desc * desc)

dispose of a GPIO descriptor

Parameters

struct gpio_desc * desc
GPIO descriptor to dispose of

Description

No descriptor can be used after gpiod_put() has been called on it.

void gpiod_put_array(struct gpio_descs * descs)

dispose of multiple GPIO descriptors

Parameters

struct gpio_descs * descs
struct gpio_descs containing an array of descriptors

ACPI support

void acpi_gpiochip_request_interrupts(struct gpio_chip * chip)

Register isr for gpio chip ACPI events

Parameters

struct gpio_chip * chip
GPIO chip

Description

ACPI5 platforms can use GPIO signaled ACPI events. These GPIO interrupts are handled by ACPI event methods which need to be called from the GPIO chip's interrupt handler. acpi_gpiochip_request_interrupts finds out which gpio pins have acpi event methods and assigns interrupt handlers that calls the acpi event methods for those pins.

void acpi_gpiochip_free_interrupts(struct gpio_chip * chip)

Free GPIO ACPI event interrupts.

Parameters

struct gpio_chip * chip
GPIO chip

Description

Free interrupts associated with GPIO ACPI event method for the given GPIO chip.

int acpi_dev_gpio_irq_get(struct acpi_device * adev, int index)

Find GpioInt and translate it to Linux IRQ number

Parameters

struct acpi_device * adev
pointer to a ACPI device to get IRQ from
int index
index of GpioInt resource (starting from 0)

Description

If the device has one or more GpioInt resources, this function can be used to translate from the GPIO offset in the resource to the Linux IRQ number.

The function is idempotent, though each time it runs it will configure GPIO pin direction according to the flags in GpioInt resource.

Return

Linux IRQ number (> 0) on success, negative errno on failure.

Device tree support

int of_gpio_simple_xlate(struct gpio_chip * gc, const struct of_phandle_args * gpiospec, u32 * flags)

translate gpiospec to the GPIO number and flags

Parameters

struct gpio_chip * gc
pointer to the gpio_chip structure
const struct of_phandle_args * gpiospec
GPIO specifier as found in the device tree
u32 * flags
a flags pointer to fill in

Description

This is simple translation function, suitable for the most 1:1 mapped GPIO chips. This function performs only one sanity check: whether GPIO is less than ngpios (that is specified in the gpio_chip).

int of_mm_gpiochip_add_data(struct device_node * np, struct of_mm_gpio_chip * mm_gc, void * data)

Add memory mapped GPIO chip (bank)

Parameters

struct device_node * np
device node of the GPIO chip
struct of_mm_gpio_chip * mm_gc
pointer to the of_mm_gpio_chip allocated structure
void * data
driver data to store in the struct gpio_chip

Description

To use this function you should allocate and fill mm_gc with:

  1. In the gpio_chip structure: - all the callbacks - of_gpio_n_cells - of_xlate callback (optional)
  1. In the of_mm_gpio_chip structure: - save_regs callback (optional)

If succeeded, this function will map bank's memory and will do all necessary work for you. Then you'll able to use .regs to manage GPIOs from the callbacks.

void of_mm_gpiochip_remove(struct of_mm_gpio_chip * mm_gc)

Remove memory mapped GPIO chip (bank)

Parameters

struct of_mm_gpio_chip * mm_gc
pointer to the of_mm_gpio_chip allocated structure

Device-managed API

struct gpio_desc * devm_gpiod_get(struct device * dev, const char * con_id, enum gpiod_flags flags)

Resource-managed gpiod_get()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get() for detailed information about behavior and return values.

struct gpio_desc * devm_gpiod_get_optional(struct device * dev, const char * con_id, enum gpiod_flags flags)

Resource-managed gpiod_get_optional()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get_optional(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get_optional() for detailed information about behavior and return values.

struct gpio_desc * devm_gpiod_get_index(struct device * dev, const char * con_id, unsigned int idx, enum gpiod_flags flags)

Resource-managed gpiod_get_index()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
unsigned int idx
index of the GPIO to obtain in the consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get_index(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get_index() for detailed information about behavior and return values.

struct gpio_desc * devm_gpiod_get_from_of_node(struct device * dev, struct device_node * node, const char * propname, int index, enum gpiod_flags dflags, const char * label)

obtain a GPIO from an OF node

Parameters

struct device * dev
device for lifecycle management
struct device_node * node
handle of the OF node
const char * propname
name of the DT property representing the GPIO
int index
index of the GPIO to obtain for the consumer
enum gpiod_flags dflags
GPIO initialization flags
const char * label
label to attach to the requested GPIO

Return

On successful request the GPIO pin is configured in accordance with provided dflags.

In case of error an ERR_PTR() is returned.

struct gpio_desc * devm_fwnode_get_index_gpiod_from_child(struct device * dev, const char * con_id, int index, struct fwnode_handle * child, enum gpiod_flags flags, const char * label)

get a GPIO descriptor from a device's child node

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
int index
index of the GPIO to obtain in the consumer
struct fwnode_handle * child
firmware node (child of dev)
enum gpiod_flags flags
GPIO initialization flags
const char * label
label to attach to the requested GPIO

Description

GPIO descriptors returned from this function are automatically disposed on driver detach.

On successful request the GPIO pin is configured in accordance with provided flags.

struct gpio_desc * devm_gpiod_get_index_optional(struct device * dev, const char * con_id, unsigned int index, enum gpiod_flags flags)

Resource-managed gpiod_get_index_optional()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
unsigned int index
index of the GPIO to obtain in the consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get_index_optional(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get_index_optional() for detailed information about behavior and return values.

struct gpio_descs * devm_gpiod_get_array(struct device * dev, const char * con_id, enum gpiod_flags flags)

Resource-managed gpiod_get_array()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get_array(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get_array() for detailed information about behavior and return values.

struct gpio_descs * devm_gpiod_get_array_optional(struct device * dev, const char * con_id, enum gpiod_flags flags)

Resource-managed gpiod_get_array_optional()

Parameters

struct device * dev
GPIO consumer
const char * con_id
function within the GPIO consumer
enum gpiod_flags flags
optional GPIO initialization flags

Description

Managed gpiod_get_array_optional(). GPIO descriptors returned from this function are automatically disposed on driver detach. See gpiod_get_array_optional() for detailed information about behavior and return values.

void devm_gpiod_put(struct device * dev, struct gpio_desc * desc)

Resource-managed gpiod_put()

Parameters

struct device * dev
GPIO consumer
struct gpio_desc * desc
GPIO descriptor to dispose of

Description

Dispose of a GPIO descriptor obtained with devm_gpiod_get() or devm_gpiod_get_index(). Normally this function will not be called as the GPIO will be disposed of by the resource management code.

void devm_gpiod_put_array(struct device * dev, struct gpio_descs * descs)

Resource-managed gpiod_put_array()

Parameters

struct device * dev
GPIO consumer
struct gpio_descs * descs
GPIO descriptor array to dispose of

Description

Dispose of an array of GPIO descriptors obtained with devm_gpiod_get_array(). Normally this function will not be called as the GPIOs will be disposed of by the resource management code.

int devm_gpio_request(struct device * dev, unsigned gpio, const char * label)

request a GPIO for a managed device

Parameters

struct device * dev
device to request the GPIO for
unsigned gpio
GPIO to allocate
const char * label
the name of the requested GPIO

Description

Except for the extra dev argument, this function takes the same arguments and performs the same function as gpio_request(). GPIOs requested with this function will be automatically freed on driver detach.

If an GPIO allocated with this function needs to be freed separately, devm_gpio_free() must be used.

int devm_gpio_request_one(struct device * dev, unsigned gpio, unsigned long flags, const char * label)

request a single GPIO with initial setup

Parameters

struct device * dev
device to request for
unsigned gpio
the GPIO number
unsigned long flags
GPIO configuration as specified by GPIOF_*
const char * label
a literal description string of this GPIO
void devm_gpio_free(struct device * dev, unsigned int gpio)

free a GPIO

Parameters

struct device * dev
device to free GPIO for
unsigned int gpio
GPIO to free

Description

Except for the extra dev argument, this function takes the same arguments and performs the same function as gpio_free(). This function instead of gpio_free() should be used to manually free GPIOs allocated with devm_gpio_request().

sysfs helpers

int gpiod_export(struct gpio_desc * desc, bool direction_may_change)

export a GPIO through sysfs

Parameters

struct gpio_desc * desc
GPIO to make available, already requested
bool direction_may_change
true if userspace may change GPIO direction

Context

arch_initcall or later

Description

When drivers want to make a GPIO accessible to userspace after they have requested it -- perhaps while debugging, or as part of their public interface -- they may use this routine. If the GPIO can change direction (some can't) and the caller allows it, userspace will see "direction" sysfs attribute which may be used to change the gpio's direction. A "value" attribute will always be provided.

Returns zero on success, else an error.

create a sysfs link to an exported GPIO node

Parameters

struct device * dev
device under which to create symlink
const char * name
name of the symlink
struct gpio_desc * desc
GPIO to create symlink to, already exported

Description

Set up a symlink from /sys/.../dev/name to /sys/class/gpio/gpioN node. Caller is responsible for unlinking.

Returns zero on success, else an error.

void gpiod_unexport(struct gpio_desc * desc)

reverse effect of gpiod_export()

Parameters

struct gpio_desc * desc
GPIO to make unavailable

Description

This is implicit on gpiod_free().