mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-12-24 03:53:31 +00:00
66 lines
2.3 KiB
ReStructuredText
66 lines
2.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
|
|
|
|
Events
|
|
======
|
|
|
|
U-Boot supports a way for various events to be handled by interested
|
|
subsystems. This provide a generic way to handle 'hooks' like setting up the
|
|
CPUs after driver model is active, or reading a partition table after a new
|
|
block device is probed.
|
|
|
|
Rather than using weak functions and direct calls across subsystemss, it is
|
|
often easier to use an event.
|
|
|
|
An event consists of a type (e.g. EVT_DM_POST_INIT) and some optional data,
|
|
in `union event_data`. An event spy can be creasted to watch for events of a
|
|
particular type. When the event is created, it is sent to each spy in turn.
|
|
|
|
|
|
Declaring a spy
|
|
---------------
|
|
|
|
To declare a spy, use something like this::
|
|
|
|
static int snow_setup_cpus(void *ctx, struct event *event)
|
|
{
|
|
/* do something */
|
|
return 0;
|
|
}
|
|
EVENT_SPY(EVT_DM_POST_INIT, snow_setup_cpus);
|
|
|
|
Your function is called when EVT_DM_POST_INIT is emitted, i.e. after driver
|
|
model is inited (in SPL, or in U-Boot proper before and after relocation).
|
|
|
|
|
|
Debugging
|
|
---------
|
|
|
|
To assist with debugging events, enable `CONFIG_EVENT_DEBUG` and
|
|
`CONFIG_CMD_EVENT`. The :doc:`../usage/cmd/event` command can then be used to
|
|
provide a spy list.
|
|
|
|
It is also possible to list spy information from the U-Boot executable,, using
|
|
the `event_dump.py` script::
|
|
|
|
$ scripts/event_dump.py /tmp/b/sandbox/u-boot
|
|
Event type Id Source location
|
|
-------------------- ------------------------------ ------------------------------
|
|
EVT_MISC_INIT_F f:sandbox_misc_init_f arch/sandbox/cpu/start.c:125
|
|
|
|
This shows each event spy in U-Boot, along with the event type, function name
|
|
(or ID) and source location.
|
|
|
|
Note that if `CONFIG_EVENT_DEBUG` is not enabled, the event ID is missing, so
|
|
the function is shown instead (with an `f:` prefix as above). Since the ID is
|
|
generally the same as the function name, this does not matter much.
|
|
|
|
The event type is decoded by the symbol used by U-Boot for the event linker
|
|
list. Symbols have the form::
|
|
|
|
_u_boot_list_2_evspy_info_2_EVT_MISC_INIT_F
|
|
|
|
so the event type can be read from the end. To manually list spy information
|
|
in an image, use $(CROSS_COMPILE)nm::
|
|
|
|
nm u-boot |grep evspy |grep list
|
|
00000000002d6300 D _u_boot_list_2_evspy_info_2_EVT_MISC_INIT_F
|