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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;
#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);
    int (*populate_parent_alloc_arg)(struct gpio_chip *gc,union gpio_irq_fwspec *fwspec,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;
    union {
        void *parent_handler_data;
        void **parent_handler_data_array;
    };
    unsigned int num_parents;
    unsigned int *parents;
    unsigned int *map;
    bool threaded;
    bool per_parent_data;
    bool initialized;
    bool domain_is_allocated_externally;
    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);
    void (*irq_unmask)(struct irq_data *data);
    void (*irq_mask)(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.

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.

{unnamed_union}

anonymous

parent_handler_data

If per_parent_data is false, parent_handler_data is a single pointer used as the data associated with every parent interrupt.

parent_handler_data_array

If per_parent_data is true, parent_handler_data_array is an array of num_parents pointers, and is used to associate different data for each parent. This cannot be NULL if per_parent_data is true.

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.

per_parent_data

True if parent_handler_data_array describes a num_parents sized array to be used as parent data.

initialized

Flag to track GPIO chip irq member’s initialization. This flag will make sure GPIO chip irq members are not used before they are initialized.

domain_is_allocated_externally

True it the irq_domain was allocated outside of gpiolib, in which case gpiolib won’t free the irq_domain itself.

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

irq_unmask

Store old irq_chip irq_unmask callback

irq_mask

Store old irq_chip irq_mask callback

struct gpio_chip¶: abstract a GPIO controller

Definition:

struct gpio_chip {
    const char              *label;
    struct gpio_device      *gpiodev;
    struct device           *parent;
    struct fwnode_handle    *fwnode;
    struct module           *owner;
    int (*request)(struct gpio_chip *gc, unsigned int offset);
    void (*free)(struct gpio_chip *gc, unsigned int offset);
    int (*get_direction)(struct gpio_chip *gc, unsigned int offset);
    int (*direction_input)(struct gpio_chip *gc, unsigned int offset);
    int (*direction_output)(struct gpio_chip *gc, unsigned int offset, int value);
    int (*get)(struct gpio_chip *gc, unsigned int offset);
    int (*get_multiple)(struct gpio_chip *gc,unsigned long *mask, unsigned long *bits);
    void (*set)(struct gpio_chip *gc, unsigned int offset, int value);
    void (*set_multiple)(struct gpio_chip *gc,unsigned long *mask, unsigned long *bits);
    int (*set_config)(struct gpio_chip *gc,unsigned int offset, unsigned long config);
    int (*to_irq)(struct gpio_chip *gc, unsigned int 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 (*en_hw_timestamp)(struct gpio_chip *gc,u32 offset, unsigned long flags);
    int (*dis_hw_timestamp)(struct gpio_chip *gc,u32 offset, unsigned long flags);
    int base;
    u16 ngpio;
    u16 offset;
    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;
    raw_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);
    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
fwnode: optional fwnode providing this controller’s properties
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 GPIO_LINE_DIRECTION_OUT / GPIO_LINE_DIRECTION_IN), 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, returns 0 on success or a negative error number. This can be omitted on input-only or output-only gpio chips.
direction_output: configures signal “offset” as output, returns 0 on success or a negative error number. 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 gpiod_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.
en_hw_timestamp: Dependent on GPIO chip, an optional routine to enable hardware timestamp.
dis_hw_timestamp: Dependent on GPIO chip, an optional routine to disable hardware timestamp.
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).
offset: when multiple gpio chips belong to the same device this can be used as offset within the device so friendly names can be properly assigned.
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.
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_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 programming 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.

for_each_hwgpio¶

for_each_hwgpio (_chip, _i, _label)

Iterates over all GPIOs for given chip.

Parameters

_chip: Chip to iterate over.
_i: Loop counter.
_label: Place to store the address of the label if the GPIO is requested. Set to NULL for unused GPIOs.

for_each_requested_gpio_in_range¶

for_each_requested_gpio_in_range (_chip, _i, _base, _size, _label)

iterates over requested GPIOs in a given range

Parameters

_chip: the chip to query
_i: loop variable
_base: first GPIO in the range
_size: amount of GPIOs to check starting from base
_label: label of current GPIO

gpiochip_add_data¶

gpiochip_add_data (gc, data)

register a gpio_chip

Parameters

gc: the chip to register, with gc->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 gc->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, i.e. after core_initcall().

If gc->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 gc->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 *gpio_device_get_desc(struct gpio_device *gdev, unsigned int hwnum)¶: get the GPIO descriptor corresponding to the given hardware number for this GPIO device

Parameters

struct gpio_device *gdev: GPIO device to get the descriptor from
unsigned int hwnum: hardware number of the GPIO for this chip

Return

A pointer to the GPIO descriptor or EINVAL if no GPIO exists in the given chip for the specified hardware number or ENODEV if the underlying chip already vanished.

Description

The reference count of struct gpio_device is NOT increased like when the GPIO is being requested for exclusive usage. It’s up to the caller to make sure the GPIO device will stay alive together with the descriptor returned by this function.

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

Description

DEPRECATED This function is unsafe and should not be used. Using the chip address without taking the SRCU read lock may result in dereferencing a dangling pointer.

Return

Address of the GPIO chip backing this device.

struct gpio_device *gpiod_to_gpio_device(struct gpio_desc *desc)¶: Return the GPIO device to which this descriptor belongs.

Parameters

struct gpio_desc *desc: Descriptor for which to return the GPIO device.

Description

This DOES NOT increase the reference count of the GPIO device as it’s expected that the descriptor is requested and the users already holds a reference to the device.

Return

Address of the GPIO device owning this descriptor.

int gpio_device_get_base(struct gpio_device *gdev)¶: Get the base GPIO number allocated by this device

Parameters

struct gpio_device *gdev: GPIO device

Return

First GPIO number in the global GPIO numberspace for this device.

const char *gpio_device_get_label(struct gpio_device *gdev)¶: Get the label of this GPIO device

Parameters

struct gpio_device *gdev: GPIO device

Return

Pointer to the string containing the GPIO device label. The string’s lifetime is tied to that of the underlying GPIO device.

struct gpio_chip *gpio_device_get_chip(struct gpio_device *gdev)¶: Get the gpio_chip implementation of this GPIO device

Parameters

struct gpio_device *gdev: GPIO device

Return

Address of the GPIO chip backing this device.

Description

DEPRECATED Until we can get rid of all non-driver users of struct gpio_chip, we must provide a way of retrieving the pointer to it from struct gpio_device. This is NOT safe as the GPIO API is considered to be hot-unpluggable and the chip can dissapear at any moment (unlike reference-counted struct gpio_device).

Use at your own risk.

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

Return

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

Description

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_device *gpio_device_find(const void *data, int (*match)(struct gpio_chip *gc, const void *data))¶: find a specific GPIO device

Parameters

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

Return

New reference to struct gpio_device.

Description

Similar to bus_find_device(). It returns a reference to a gpio_device 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 returns non-zero, this function will return to the caller and not iterate over any more gpio_devices.

The callback takes the GPIO chip structure as argument. During the execution of the callback function the chip is protected from being freed. TODO: This actually has yet to be implemented.

If the function returns non-NULL, the returned reference must be freed by the caller using gpio_device_put().

struct gpio_device *gpio_device_find_by_label(const char *label)¶: wrapper around gpio_device_find() finding the GPIO device by its backing chip’s label

Parameters

const char *label: Label to lookup

Return

Reference to the GPIO device or NULL. Reference must be released with gpio_device_put().

struct gpio_device *gpio_device_find_by_fwnode(const struct fwnode_handle *fwnode)¶: wrapper around gpio_device_find() finding the GPIO device by its fwnode

Parameters

const struct fwnode_handle *fwnode: Firmware node to lookup

Return

Reference to the GPIO device or NULL. Reference must be released with gpio_device_put().

struct gpio_device *gpio_device_get(struct gpio_device *gdev)¶: Increase the reference count of this GPIO device

Parameters

struct gpio_device *gdev: GPIO device to increase the refcount for

Return

Pointer to gdev.

void gpio_device_put(struct gpio_device *gdev)¶: Decrease the reference count of this GPIO device and possibly free all resources associated with it.

Parameters

struct gpio_device *gdev: GPIO device to decrease the reference count for

struct device *gpio_device_to_device(struct gpio_device *gdev)¶: Retrieve the address of the underlying struct device.

Parameters

struct gpio_device *gdev: GPIO device for which to return the address.

Description

This does not increase the reference count of the GPIO device nor the underlying struct device.

Return

Address of struct device backing this GPIO device.

int gpiochip_irqchip_add_domain(struct gpio_chip *gc, struct irq_domain *domain)¶: adds an irqdomain to a gpiochip

Parameters

struct gpio_chip *gc: the gpiochip to add the irqchip to
struct irq_domain *domain: the irqdomain to add to the gpiochip

Description

This function adds an IRQ domain to the gpiochip.

Return

0 on success, or negative errno on failure.

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

Parameters

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

Return

0 on success, or negative errno on failure.

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

Parameters

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

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

Parameters

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

Return

0 on success, or negative errno on failure.

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.

Return

0 on success, or negative errno on failure.

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

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.

Return

0 on success, or a negative errno on failure.

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

char *gpiochip_dup_line_label(struct gpio_chip *gc, unsigned int offset)¶: Get a copy of the consumer label.

Parameters

struct gpio_chip *gc: GPIO chip controlling this line.
unsigned int offset: Hardware offset of the line.

Return

Pointer to a copy of the consumer label if the line is requested or NULL if it’s not. If a valid pointer was returned, it must be freed using kfree(). In case of a memory allocation error, the function returns ENOMEM.

Description

Must not be called from atomic context.

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 on success, or negative errno on failure.

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 on success, or negative errno on failure.

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 on success, or negative errno on failure.

int gpiod_enable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)¶: Enable hardware timestamp in nanoseconds.

Parameters

struct gpio_desc *desc: GPIO to enable.
unsigned long flags: Flags related to GPIO edge.

Return

0 on success, or negative errno on failure.

int gpiod_disable_hw_timestamp_ns(struct gpio_desc *desc, unsigned long flags)¶: Disable hardware timestamp.

Parameters

struct gpio_desc *desc: GPIO to disable.
unsigned long flags: Flags related to GPIO edge, same value as used during enable call.

Return

0 on success, or negative errno on failure.

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 int debounce)¶: sets debounce time for a GPIO

Parameters

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

Return

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

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

Return

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

Return

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

Description

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

Return

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

Description

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.

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

Return

0 on success, or negative errno on failure.

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.

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

Return

0 on success, or negative errno on failure.

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.

Return

0 on success, or negative errno on failure.

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.

Return

0 on success, or negative errno on failure.

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

Parameters

const struct gpio_desc *desc: gpio to check

Return

0 for non-sleepable, 1 for sleepable, or an error code in case of error.

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

Return

0 on success, or negative errno on failure.

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)

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.

Return

0 on success, or negative errno on failure.

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

Return

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

Description

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

Return

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

Description

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.

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

Return

0 on success, or negative errno on failure.

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.

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

Return

0 on success, or negative errno on failure.

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.

Return

0 on success, or negative errno on failure.

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.

Return

0 on success, or negative errno on failure.

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

struct gpio_desc *fwnode_gpiod_get_index(struct fwnode_handle *fwnode, const char *con_id, int index, enum gpiod_flags flags, const char *label)¶: obtain a GPIO from firmware node

Parameters

struct fwnode_handle *fwnode: handle of the firmware node
const char *con_id: function within the GPIO consumer
int index: index of the GPIO to obtain for the consumer
enum gpiod_flags flags: 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.

In case of error an ERR_PTR() is returned.

Return

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

int gpiod_count(struct device *dev, const char *con_id)¶: return the number of GPIOs associated with a device / function

Parameters

struct device *dev: GPIO consumer, can be NULL for system-global GPIOs
const char *con_id: function within the GPIO consumer

Return

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

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

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.

Return

The GPIO descriptor corresponding to the function con_id of device dev, NULL 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_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_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.

Return

A valid GPIO descriptor, NULL 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_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

The GPIO descriptors 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 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.

Return

The GPIO descriptors corresponding to the function con_id of device dev, NULL 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.

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¶

bool acpi_gpio_get_io_resource(struct acpi_resource *ares, struct acpi_resource_gpio **agpio)¶: Fetch details of an ACPI resource if it is a GPIO I/O resource or return False if not.

Parameters

struct acpi_resource *ares: Pointer to the ACPI resource to fetch
struct acpi_resource_gpio **agpio: Pointer to a struct acpi_resource_gpio to store the output pointer

Return

true if GpioIo resource is found, false otherwise.

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_wake_get_by(struct acpi_device *adev, const char *con_id, int index, bool *wake_capable)¶: Find GpioInt and translate it to Linux IRQ number

Parameters

struct acpi_device *adev: pointer to a ACPI device to get IRQ from
const char *con_id: optional name of GpioInt resource
int index: index of GpioInt resource (starting from 0)
bool *wake_capable: Set to true if the IRQ is wake capable

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.

The function takes optional con_id parameter. If the resource has a con_id in a property, then only those will be taken into account.

The GPIO is considered wake capable if the GpioInt resource specifies SharedAndWake or ExclusiveAndWake.

Return

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

Device tree support¶

int of_get_named_gpio(const struct device_node *np, const char *propname, int index)¶: Get a GPIO number to use with GPIO API

Parameters

const struct device_node *np: device node to get GPIO from
const char *propname: Name of property containing gpio specifier(s)
int index: index of the GPIO

Description

DEPRECATED This function is deprecated and must not be used in new code.

Return

GPIO number to use with Linux generic GPIO API, or one of the errno value on the error condition.

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:

In the gpio_chip structure: - all the callbacks - of_gpio_n_cells - of_xlate callback (optional)

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.

Return

0 on success, or negative errno on failure.

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.

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 *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.

Return

The GPIO descriptor corresponding to the function con_id of device dev, NULL 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 *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.

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 *devm_fwnode_gpiod_get_index(struct device *dev, struct fwnode_handle *fwnode, const char *con_id, int index, enum gpiod_flags flags, const char *label)¶: get a GPIO descriptor from a given node

Parameters

struct device *dev: GPIO consumer
struct fwnode_handle *fwnode: firmware node containing GPIO reference
const char *con_id: function within the GPIO consumer
int index: index of the GPIO to obtain in the consumer
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.

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 *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.

Return

The GPIO descriptor corresponding to the function con_id of device dev, NULL 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_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.

Return

The GPIO descriptors 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 GPIOs.

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.

Return

The GPIO descriptors corresponding to the function con_id of device dev, NULL 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.

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_unhinge(struct device *dev, struct gpio_desc *desc)¶: Remove resource management from a gpio descriptor

Parameters

struct device *dev: GPIO consumer
struct gpio_desc *desc: GPIO descriptor to remove resource management from

Description

Remove resource management from a GPIO descriptor. This is needed when you want to hand over lifecycle management of a descriptor to another mechanism.

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_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip *gc, void *data, struct lock_class_key *lock_key, struct lock_class_key *request_key)¶: Resource managed gpiochip_add_data_with_key()

Parameters

struct device *dev: pointer to the device that gpio_chip belongs to.
struct gpio_chip *gc: the GPIO chip to register
void *data: driver-private data associated with this chip
struct lock_class_key *lock_key: lockdep class for IRQ lock
struct lock_class_key *request_key: lockdep class for IRQ request

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 gc->base is invalid or already associated with a different chip. Otherwise it returns zero as a success code.

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.

Return

0 on success, or negative errno on failure.

int gpiod_export_link(struct device *dev, const char *name, struct gpio_desc *desc)¶: 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.

Return

0 on success, or negative errno on failure.

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().

The Linux Kernel

Contents

This Page

General Purpose Input/Output (GPIO)¶

Core¶

ACPI support¶

Device tree support¶

Device-managed API¶

sysfs helpers¶