1.21. 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_CUSTOM: Match will use the logic provided by struct v4l2_async_subdev.match ops
V4L2_ASYNC_MATCH_DEVNAME: Match will use the device name
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 asyncrhronous 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;
    const char *device_name;
    struct {
      int adapter_id;
      unsigned short address;
    } i2c;
    struct {
      bool (*match)(struct device *dev, struct v4l2_async_subdev *sd);
      void *priv;
    } custom;
  } 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.device_name: string containing the device name to be matched. Used if match_type is V4L2_ASYNC_MATCH_DEVNAME.
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.
match.custom: Driver-specific match criteria. Used if match_type is V4L2_ASYNC_MATCH_CUSTOM.
match.custom.match: Driver-specific match function to be used if V4L2_ASYNC_MATCH_CUSTOM.
match.custom.priv: Driver-specific private struct with match parameters to be used if V4L2_ASYNC_MATCH_CUSTOM.
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_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 the first call to v4l2_async_notifier_add_subdev.

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

Call this function before registering a notifier to link the provided asd to the notifiers master asd_list.

struct v4l2_async_subdev *v4l2_async_notifier_add_fwnode_subdev(struct v4l2_async_notifier *notifier, struct fwnode_handle *fwnode, unsigned int asd_struct_size)¶: Allocate and add a fwnode async subdev to the notifier’s master asd_list.

Parameters

struct v4l2_async_notifier * notifier: pointer to struct v4l2_async_notifier
struct fwnode_handle * fwnode: fwnode handle of the sub-device to be matched
unsigned int asd_struct_size: size of the driver’s async sub-device struct, including sizeof(struct v4l2_async_subdev). 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.

int v4l2_async_notifier_add_fwnode_remote_subdev(struct v4l2_async_notifier *notif, struct fwnode_handle *endpoint, struct v4l2_async_subdev *asd)¶: Allocate and add a fwnode remote async subdev to the notifier’s master asd_list.

Parameters

struct v4l2_async_notifier * notif: pointer to struct v4l2_async_notifier
struct fwnode_handle * endpoint: local endpoint pointing to the remote sub-device to be matched
struct v4l2_async_subdev * asd: Async sub-device struct allocated by the caller. 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, and the function relies on the caller to allocate the async sub-device struct.

struct v4l2_async_subdev *v4l2_async_notifier_add_i2c_subdev(struct v4l2_async_notifier *notifier, int adapter_id, unsigned short address, unsigned int asd_struct_size)¶: Allocate and add an i2c async subdev to the notifier’s master asd_list.

Parameters

struct v4l2_async_notifier * notifier: pointer to struct v4l2_async_notifier
int adapter_id: I2C adapter ID to be matched
unsigned short address: I2C address of sub-device to be matched
unsigned int asd_struct_size: size of the driver’s async sub-device struct, including sizeof(struct v4l2_async_subdev). 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 above but for I2C matched sub-devices.

struct v4l2_async_subdev *v4l2_async_notifier_add_devname_subdev(struct v4l2_async_notifier *notifier, const char *device_name, unsigned int asd_struct_size)¶: Allocate and add a device-name async subdev to the notifier’s master asd_list.

Parameters

struct v4l2_async_notifier * notifier: pointer to struct v4l2_async_notifier
const char * device_name: device name string to be matched
unsigned int asd_struct_size: size of the driver’s async sub-device struct, including sizeof(struct v4l2_async_subdev). 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 above but for device-name 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_subdev, v4l2_async_notifier_parse_fwnode_endpoints or v4l2_fwnode_reference_parse_sensor_common.

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_common(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_common() 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

1.21. V4L2 async kAPI¶

The Linux Kernel

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