event: Add basic support for events

Add a way to create and dispatch events without needing to allocate
memory. Also add a way to 'spy' on events, thus allowing 'hooks' to be
created.

Use a linker list for static events, which we can use to replace functions
like arch_cpu_init_f(). Allow an EVENT_DEBUG option which makes it
easier to see what is going on at runtime, but uses more code space.

Dynamic events allow the creation of a spy at runtime. This is not always
necessary, but can be enabled with EVENT_DYNAMIC if needed.

A 'test' event is the only option for now.

Signed-off-by: Simon Glass <sjg@chromium.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/common/Kconfig b/common/Kconfig
index add4cdae02..cabc24fb9c 100644
--- a/common/Kconfig
+++ b/common/Kconfig
@@ -492,6 +492,37 @@ config DISPLAY_BOARDINFO_LATE
 
 menu "Start-up hooks"
 
+config EVENT
+	bool "General-purpose event-handling mechanism"
+	default y if SANDBOX
+	help
+	  This enables sending and processing of events, to allow interested
+	  parties to be alerted when something happens. This is an attempt to
+	  step the flow of weak functions, hooks, functions in board_f.c
+	  and board_r.c and the Kconfig options below.
+
+	  See doc/develop/event.rst for more information.
+
+if EVENT
+
+config EVENT_DYNAMIC
+	bool "Support event registration at runtime"
+	default y if SANDBOX
+	help
+	  Enable this to support adding an event spy at runtime, without adding
+	  it to the EVENT_SPy() linker list. This increases code size slightly
+	  but provides more flexibility for boards and subsystems that need it.
+
+config EVENT_DEBUG
+	bool "Enable event debugging assistance"
+	default y if SANDBOX
+	help
+	  Enable this get usefui features for seeing what is happening with
+	  events, such as event-type names. This adds to the code size of
+	  U-Boot so can be turned off for production builds.
+
+endif # EVENT
+
 config ARCH_EARLY_INIT_R
 	bool "Call arch-specific init soon after relocation"
 	help