mirror of
https://github.com/AsahiLinux/u-boot
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55171aedda
The original function was only called once, before relocation. The new
one is called again after relocation. This was not the intent of the
original call. Fix this by renaming and updating the calling logic.
With this, chromebook_link64 makes it through SPL.
Fixes: 7fe32b3442 ("event: Convert arch_cpu_init_dm() to use events")
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
89 lines
3.2 KiB
ReStructuredText
89 lines
3.2 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0+
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Events
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======
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U-Boot supports a way for various events to be handled by interested
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subsystems. This provide a generic way to handle 'hooks' like setting up the
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CPUs after driver model is active, or reading a partition table after a new
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block device is probed.
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Rather than using weak functions and direct calls across subsystemss, it is
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often easier to use an event.
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An event consists of a type (e.g. EVT_DM_POST_INIT_F) and some optional data,
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in `union event_data`. An event spy can be created to watch for events of a
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particular type. When the event is created, it is sent to each spy in turn.
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Declaring a spy
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---------------
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To declare a spy, use something like this::
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static int snow_setup_cpus(void *ctx, struct event *event)
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{
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/* do something */
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return 0;
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}
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EVENT_SPY(EVT_DM_POST_INIT_F, snow_setup_cpus);
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Your function is called when EVT_DM_POST_INIT_F is emitted, i.e. after driver
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model is inited (in SPL, or in U-Boot proper before and after relocation).
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Debugging
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---------
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To assist with debugging events, enable `CONFIG_EVENT_DEBUG` and
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`CONFIG_CMD_EVENT`. The :doc:`../usage/cmd/event` command can then be used to
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provide a spy list.
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It is also possible to list spy information from the U-Boot executable,, using
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the `event_dump.py` script::
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$ scripts/event_dump.py /tmp/b/sandbox/u-boot
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Event type Id Source location
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-------------------- ------------------------------ ------------------------------
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EVT_MISC_INIT_F f:sandbox_misc_init_f arch/sandbox/cpu/start.c:125
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This shows each event spy in U-Boot, along with the event type, function name
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(or ID) and source location.
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Note that if `CONFIG_EVENT_DEBUG` is not enabled, the event ID is missing, so
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the function is shown instead (with an `f:` prefix as above). Since the ID is
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generally the same as the function name, this does not matter much.
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The event type is decoded by the symbol used by U-Boot for the event linker
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list. Symbols have the form::
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_u_boot_list_2_evspy_info_2_EVT_MISC_INIT_F
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so the event type can be read from the end. To manually list spy information
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in an image, use $(CROSS_COMPILE)nm::
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nm u-boot |grep evspy |grep list
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00000000002d6300 D _u_boot_list_2_evspy_info_2_EVT_MISC_INIT_F
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Logging is also available. Events use category `LOGC_EVENT`, so you can enable
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logging on that, or add `#define LOG_DEBUG` to the top of `common/event.c` to
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see events being sent.
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Dynamic events
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--------------
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Static events provide a way of dealing with events known at build time. In some
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cases we want to attach an event handler at runtime. For example, we may wish
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to be notified when a particular device is probed or removed.
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This can be handled by enabling `CONFIG_EVENT_DYNAMIC`. It is then possible to
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call `event_register()` to register a new handler for a particular event.
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Dynamic event handlers are called after all the static event spy handlers have
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been processed. Of course, since dynamic event handlers are created at runtime
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it is not possible to use the `event_dump.py` to see them.
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At present there is no way to list dynamic event handlers from the command line,
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nor to deregister a dynamic event handler. These features can be added when
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needed.
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