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_handleto 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_connectionobjects 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_connectionshall 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_connectionshall 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_connectionshall 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_connectionfor 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