2.21. 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_I2C
Match will check for I2C adapter ID and address
V4L2_ASYNC_MATCH_FWNODE
Match will use firmware node

Description

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

struct v4l2_async_subdev

sub-device descriptor, as known to a bridge

Definition

struct v4l2_async_subdev {
  enum v4l2_async_match_type match_type;
  union {
    struct fwnode_handle *fwnode;
    struct {
      int adapter_id;
      unsigned short address;
    } i2c;
  } match;
  struct list_head list;
  struct list_head asd_list;
};

Members

match_type
type of match that will be used
match
union of per-bus type matching data sets

match.fwnode

pointer to struct fwnode_handle to be matched. Used if match_type is V4L2_ASYNC_MATCH_FWNODE.
match.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_I2C.

match.i2c.adapter_id

I2C adapter ID to be matched. Used if match_type is V4L2_ASYNC_MATCH_I2C.

match.i2c.address

I2C address to be matched. Used if match_type is V4L2_ASYNC_MATCH_I2C.
list
used to link struct v4l2_async_subdev objects, waiting to be probed, to a notifier->waiting list
asd_list
used to add struct v4l2_async_subdev objects to the master notifier asd_list

Description

When this struct is used as a member in a driver specific struct, the driver specific struct shall contain the struct v4l2_async_subdev 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_subdev *asd);
  int (*complete)(struct v4l2_async_notifier *notifier);
  void (*unbind)(struct v4l2_async_notifier *notifier,struct v4l2_subdev *subdev, struct v4l2_async_subdev *asd);
};

Members

bound
a subdevice driver has successfully probed one of the subdevices
complete
All subdevices have been probed successfully. The complete callback is only executed for the root notifier.
unbind
a subdevice is leaving
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 asd_list;
  struct list_head waiting;
  struct list_head done;
  struct list_head list;
};

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
asd_list
master list of struct v4l2_async_subdev
waiting
list of struct v4l2_async_subdev, waiting for their drivers
done
list of struct v4l2_subdev, already probed
list
member in a global list of notifiers
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_notifier_init(struct v4l2_async_notifier *notifier)

Initialize a notifier.

Parameters

struct v4l2_async_notifier *notifier
pointer to struct v4l2_async_notifier

Description

This function initializes the notifier asd_list. It must be called before adding a subdevice to a notifier, using one of: v4l2_async_notifier_add_fwnode_remote_subdev(), v4l2_async_notifier_add_fwnode_subdev(), v4l2_async_notifier_add_i2c_subdev(), __v4l2_async_notifier_add_subdev() or v4l2_async_notifier_parse_fwnode_endpoints().

int __v4l2_async_notifier_add_subdev(struct v4l2_async_notifier *notifier, struct v4l2_async_subdev *asd)

Add an async subdev to the notifier’s master asd list.

Parameters

struct v4l2_async_notifier *notifier
pointer to struct v4l2_async_notifier
struct v4l2_async_subdev *asd
pointer to struct v4l2_async_subdev

Description

warning: Drivers should avoid using this function and instead use one of: v4l2_async_notifier_add_fwnode_subdev(), v4l2_async_notifier_add_fwnode_remote_subdev() or v4l2_async_notifier_add_i2c_subdev().

Call this function before registering a notifier to link the provided asd to the notifiers master asd_list. The asd must be allocated with k*alloc() as it will be freed by the framework when the notifier is destroyed.

v4l2_async_notifier_add_fwnode_subdev(notifier, fwnode, type)

Allocate and add a fwnode async subdev to the notifier’s master asd_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 struct. The struct v4l2_async_subdev shall be the first member of the driver’s async sub-device struct, i.e. both begin at the same memory address.

Description

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

v4l2_async_notifier_add_fwnode_remote_subdev(notifier, ep, type)

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

Parameters

notifier
pointer to struct v4l2_async_notifier
ep
local endpoint pointing to the remote sub-device to be matched, pointer to struct fwnode_handle
type
Type of the driver’s async sub-device struct. The struct v4l2_async_subdev shall be the first member of the driver’s async sub-device 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 sub-device to the notifier’s asd_list. The function also gets a reference of the fwnode which is released later at notifier cleanup time.

This is just like v4l2_async_notifier_add_fwnode_subdev(), but with the exception that the fwnode refers to a local endpoint, not the remote one.

v4l2_async_notifier_add_i2c_subdev(notifier, adapter, address, type)

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

Parameters

notifier
pointer to struct v4l2_async_notifier
adapter
I2C adapter ID to be matched
address
I2C address of sub-device to be matched
type
Type of the driver’s async sub-device struct. The struct v4l2_async_subdev shall be the first member of the driver’s async sub-device struct, i.e. both begin at the same memory address.

Description

Same as v4l2_async_notifier_add_fwnode_subdev() but for I2C matched sub-devices.

int v4l2_async_notifier_register(struct v4l2_device *v4l2_dev, struct v4l2_async_notifier *notifier)

registers a subdevice asynchronous notifier

Parameters

struct v4l2_device *v4l2_dev
pointer to struct v4l2_device
struct v4l2_async_notifier *notifier
pointer to struct v4l2_async_notifier
int v4l2_async_subdev_notifier_register(struct v4l2_subdev *sd, struct v4l2_async_notifier *notifier)

registers a subdevice asynchronous notifier for a sub-device

Parameters

struct v4l2_subdev *sd
pointer to struct v4l2_subdev
struct v4l2_async_notifier *notifier
pointer to struct v4l2_async_notifier
void v4l2_async_notifier_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_notifier_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 sub-devices 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_notifier_add_fwnode_remote_subdev(), v4l2_async_notifier_add_fwnode_subdev(), v4l2_async_notifier_add_i2c_subdev(), __v4l2_async_notifier_add_subdev() or v4l2_async_notifier_parse_fwnode_endpoints().

There is no harm from calling v4l2_async_notifier_cleanup() in other cases as long as its memory has been zeroed after it has been allocated.

int v4l2_async_register_subdev(struct v4l2_subdev *sd)

registers a sub-device to the asynchronous subdevice framework

Parameters

struct v4l2_subdev *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_notifier_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