Bluetooth: Define connection event prepare callbacks

[rugeGerritsen]

The connection event callback feature replaces
the radio notification feature. It can be used to
synchronize data sampling with Bluetooth connection events.

The old feature had several weaknesses:

• It was not possible to know which connection
  the notification belonged to.
• The trigger also happened upon flash access.
• The time from trigger until event start was fixed.
  That is, not configurable per use case.

The new feature is built on top of the connection event
trigger feature and is therefore able to known
which connection a given notification belongs to.

This PR is done on top of #15798 to simplify the implementation

[NordicBuilder]

You can find the documentation preview for this PR at this link. It will be updated about 10 minutes after the documentation build succeeds.

Note: This comment is automatically posted by the Documentation Publishing GitHub Action.

[rugeGerritsen]

Other suggestion: Add the possibility to trigger a callback at the start of the events.

Then it might make sense to define the callback as a struct so that it is possible to later add start() and end() if requested.

struct bt_conn_evt_cb {
	 void (*prepare)(struct bt_conn *conn, void *user_data);
	 void (*start)((struct bt_conn *conn, void *user_data);
	 void (*end)((struct bt_conn *conn, void *user_data);
}, 

int bt_conn_evt_cb_register(const struct bt_conn *conn, struct bt_conn_evt_cb cb,
			       void *user_data,
			       uint32_t prepare_distance_us);

[NordicBuilder]

Test specification

CI/Jenkins/NRF

• Integration Platforms

CI/Jenkins/integration

Test Module	File based changes	Manually selected	West overwrite
desktop52_verification	X
test-fw-nrfconnect-apps	X
test-fw-nrfconnect-ble_samples	X
test-fw-nrfconnect-fem	X
test-fw-nrfconnect-rs	X
test-sdk-find-my	X
test_ble_commit	X

Detailed information of selected test modules

Note: This message is automatically posted and updated by the CI

[seko-nordic]

does not work on 54?

[rugeGerritsen]

Not yet. Need to add EGU definitions here: https://github.com/zephyrproject-rtos/zephyr/blob/main/modules/hal_nordic/nrfx/Kconfig#L64. I believe we can do that separately to unblock other work

[rugeGerritsen]

Will be possible after zephyrproject-rtos/zephyr#75866 is in NCS

[Tschet1]

Should we combine this with the previous paragraph? I think they logically belong together.

Dismissing Aleksanders' review. The changes pushed later were pairprogrammed with him