2.22. V4L2 async kAPI

enum v4l2_async_match_type

type of asynchronous subdevice logic to be used in order to identify a match

Constants

V4L2_ASYNC_MATCH_TYPE_I2C

Match will check for I2C adapter ID and address

V4L2_ASYNC_MATCH_TYPE_FWNODE

Match will use firmware node

Description

This enum is used by the asynchronous connection logic to define the algorithm that will be used to match an asynchronous device.

struct v4l2_async_match_desc

async connection match information

Definition:

struct v4l2_async_match_desc {
    enum v4l2_async_match_type type;
    union {
        struct fwnode_handle *fwnode;
        struct {
            int adapter_id;
            unsigned short address;
        } i2c;
    };
};

Members

type

type of match that will be used

{unnamed_union}

anonymous

fwnode

pointer to struct fwnode_handle to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_FWNODE.

i2c

embedded struct with I2C parameters to be matched. Both match.i2c.adapter_id and match.i2c.address should be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

i2c.adapter_id

I2C adapter ID to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

i2c.address

I2C address to be matched. Used if match_type is V4L2_ASYNC_MATCH_TYPE_I2C.

struct v4l2_async_connection

sub-device connection descriptor, as known to a bridge

Definition:

struct v4l2_async_connection {
    struct v4l2_async_match_desc match;
    struct v4l2_async_notifier *notifier;
    struct list_head asc_entry;
    struct list_head asc_subdev_entry;
    struct v4l2_subdev *sd;
};

Members

match

struct of match type and per-bus type matching data sets

notifier

the async notifier the connection is related to

asc_entry

used to add struct v4l2_async_connection objects to the notifier waiting_list or done_list

asc_subdev_entry

entry in struct v4l2_async_subdev.asc_list list

sd

the related sub-device

Description

When this struct is used as a member in a driver specific struct, the driver specific struct shall contain the struct v4l2_async_connection as its first member.

struct v4l2_async_notifier_operations

Asynchronous V4L2 notifier operations

Definition:

struct v4l2_async_notifier_operations {
    int (*bound)(struct v4l2_async_notifier *notifier,struct v4l2_subdev *subdev, struct v4l2_async_connection *asc);
    int (*complete)(struct v4l2_async_notifier *notifier);
    void (*unbind)(struct v4l2_async_notifier *notifier,struct v4l2_subdev *subdev, struct v4l2_async_connection *asc);
    void (*destroy)(struct v4l2_async_connection *asc);
};

Members

bound

a sub-device has been bound by the given connection

complete

All connections have been bound successfully. The complete callback is only executed for the root notifier.

unbind

a subdevice is leaving

destroy

the asc is about to be freed

struct v4l2_async_notifier

v4l2_device notifier data

Definition:

struct v4l2_async_notifier {
    const struct v4l2_async_notifier_operations *ops;
    struct v4l2_device *v4l2_dev;
    struct v4l2_subdev *sd;
    struct v4l2_async_notifier *parent;
    struct list_head waiting_list;
    struct list_head done_list;
    struct list_head notifier_entry;
};

Members

ops

notifier operations

v4l2_dev

v4l2_device of the root notifier, NULL otherwise

sd

sub-device that registered the notifier, NULL otherwise

parent

parent notifier

waiting_list

list of struct v4l2_async_connection, waiting for their drivers

done_list

list of struct v4l2_subdev, already probed

notifier_entry

member in a global list of notifiers

struct v4l2_async_subdev_endpoint

Entry in sub-device’s fwnode list

Definition:

struct v4l2_async_subdev_endpoint {
    struct list_head async_subdev_endpoint_entry;
    struct fwnode_handle *endpoint;
};

Members

async_subdev_endpoint_entry

An entry in async_subdev_endpoint_list of struct v4l2_subdev

endpoint

Endpoint fwnode agains which to match the sub-device

void v4l2_async_debug_init(struct dentry *debugfs_dir)

Initialize debugging tools.

Parameters

struct dentry *debugfs_dir

pointer to the parent debugfs struct dentry

void v4l2_async_nf_init(struct v4l2_async_notifier *notifier, struct v4l2_device *v4l2_dev)

Initialize a notifier.

Parameters

struct v4l2_async_notifier *notifier

pointer to struct v4l2_async_notifier

struct v4l2_device *v4l2_dev

pointer to struct v4l2_device

Description

This function initializes the notifier asc_entry. It must be called before adding a subdevice to a notifier, using one of: v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

void v4l2_async_subdev_nf_init(struct v4l2_async_notifier *notifier, struct v4l2_subdev *sd)

Initialize a sub-device notifier.

Parameters

struct v4l2_async_notifier *notifier

pointer to struct v4l2_async_notifier

struct v4l2_subdev *sd

pointer to struct v4l2_subdev

Description

This function initializes the notifier asc_list. It must be called before adding a subdevice to a notifier, using one of: v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

v4l2_async_nf_add_fwnode

v4l2_async_nf_add_fwnode (notifier, fwnode, type)

Allocate and add a fwnode async subdev to the notifier’s master asc_list.

Parameters

notifier

pointer to struct v4l2_async_notifier

fwnode

fwnode handle of the sub-device to be matched, pointer to struct fwnode_handle

type

Type of the driver’s async sub-device or connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async struct, i.e. both begin at the same memory address.

Description

Allocate a fwnode-matched asc of size asc_struct_size, and add it to the notifiers asc_list. The function also gets a reference of the fwnode which is released later at notifier cleanup time.

v4l2_async_nf_add_fwnode_remote

v4l2_async_nf_add_fwnode_remote (notifier, ep, type)

Allocate and add a fwnode remote async subdev to the notifier’s master asc_list.

Parameters

notifier

pointer to struct v4l2_async_notifier

ep

local endpoint pointing to the remote connection to be matched, pointer to struct fwnode_handle

type

Type of the driver’s async connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async connection struct, i.e. both begin at the same memory address.

Description

Gets the remote endpoint of a given local endpoint, set it up for fwnode matching and adds the async connection to the notifier’s asc_list. The function also gets a reference of the fwnode which is released later at notifier cleanup time.

This is just like v4l2_async_nf_add_fwnode(), but with the exception that the fwnode refers to a local endpoint, not the remote one.

v4l2_async_nf_add_i2c

v4l2_async_nf_add_i2c (notifier, adapter, address, type)

Allocate and add an i2c async subdev to the notifier’s master asc_list.

Parameters

notifier

pointer to struct v4l2_async_notifier

adapter

I2C adapter ID to be matched

address

I2C address of connection to be matched

type

Type of the driver’s async connection struct. The struct v4l2_async_connection shall be the first member of the driver’s async connection struct, i.e. both begin at the same memory address.

Description

Same as v4l2_async_nf_add_fwnode() but for I2C matched connections.

int v4l2_async_subdev_endpoint_add(struct v4l2_subdev *sd, struct fwnode_handle *fwnode)

Add an endpoint fwnode to async sub-device matching list

Parameters

struct v4l2_subdev *sd

the sub-device

struct fwnode_handle *fwnode

the endpoint fwnode to match

Description

Add a fwnode to the async sub-device’s matching list. This allows registering multiple async sub-devices from a single device.

Note that calling v4l2_subdev_cleanup() as part of the sub-device’s cleanup if endpoints have been added to the sub-device’s fwnode matching list.

Returns an error on failure, 0 on success.

struct v4l2_async_connection *v4l2_async_connection_unique(struct v4l2_subdev *sd)

return a unique struct v4l2_async_connection for a sub-device

Parameters

struct v4l2_subdev *sd

the sub-device

Description

Return an async connection for a sub-device, when there is a single one only.

int v4l2_async_nf_register(struct v4l2_async_notifier *notifier)

registers a subdevice asynchronous notifier

Parameters

struct v4l2_async_notifier *notifier

pointer to struct v4l2_async_notifier

void v4l2_async_nf_unregister(struct v4l2_async_notifier *notifier)

unregisters a subdevice asynchronous notifier

Parameters

struct v4l2_async_notifier *notifier

pointer to struct v4l2_async_notifier

void v4l2_async_nf_cleanup(struct v4l2_async_notifier *notifier)

clean up notifier resources

Parameters

struct v4l2_async_notifier *notifier

the notifier the resources of which are to be cleaned up

Description

Release memory resources related to a notifier, including the async connections allocated for the purposes of the notifier but not the notifier itself. The user is responsible for calling this function to clean up the notifier after calling v4l2_async_nf_add_fwnode_remote(), v4l2_async_nf_add_fwnode() or v4l2_async_nf_add_i2c().

There is no harm from calling v4l2_async_nf_cleanup() in other cases as long as its memory has been zeroed after it has been allocated.

v4l2_async_register_subdev

v4l2_async_register_subdev (sd)

registers a sub-device to the asynchronous subdevice framework

Parameters

sd

pointer to struct v4l2_subdev

int v4l2_async_register_subdev_sensor(struct v4l2_subdev *sd)

registers a sensor sub-device to the asynchronous sub-device framework and parse set up common sensor related devices

Parameters

struct v4l2_subdev *sd

pointer to struct v4l2_subdev

Description

This function is just like v4l2_async_register_subdev() with the exception that calling it will also parse firmware interfaces for remote references using v4l2_async_nf_parse_fwnode_sensor() and registers the async sub-devices. The sub-device is similarly unregistered by calling v4l2_async_unregister_subdev().

While registered, the subdev module is marked as in-use.

An error is returned if the module is no longer loaded on any attempts to register it.

void v4l2_async_unregister_subdev(struct v4l2_subdev *sd)

unregisters a sub-device to the asynchronous subdevice framework

Parameters

struct v4l2_subdev *sd

pointer to struct v4l2_subdev