Merge branch '2022-03-09-events-subsystem' into nextnext

To quote the author:
It is a common need in U-Boot to have one subsystem notify another
when something happens. An example is reading a partition table when a
new block device is set up.

It is also common to add weak functions and 'hook' functions to modify
how U-Boot works. See for example ft_board_setup() and the like.

U-Boot would benefit from a generic mechanism to handle these cases,
with the ability to hook into various 'events' in a
subsystem-independent and transparent way.

This series provides a way to create and dispatch events, with a way of
registering a 'spy' which watches for events of different types. This
allows 'hook' functions to be created in a generic way.

It also includes a script to list the hooks in an image, which is a bit
easier to debug than weak functions, as well as an 'event' command to
do the same from within U-Boot.

These 'static' events can be used to replace hooks like misc_init_f(),
for example. Also included is basic support for 'dynamic' events, where
a spy can be registered at runtime. The need for this is still being
figured out.

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/core/Kconfig b/drivers/core/Kconfig
index 8f7703c..5c34004 100644
--- a/drivers/core/Kconfig
+++ b/drivers/core/Kconfig
@@ -77,6 +77,16 @@ config DM_DEVICE_REMOVE
 	  it causes unplugged devices to linger around in the dm-tree, and it
 	  causes USB host controllers to not be stopped when booting the OS.
 
+config DM_EVENT
+	bool "Support events with driver model"
+	depends on DM
+	imply EVENT
+	default y if SANDBOX
+	help
+	  This enables support for generating events related to driver model
+	  operations, such as prbing or removing a device. Subsystems can
+	  register a 'spy' function that is called when the event occurs.
+
 config SPL_DM_DEVICE_REMOVE
 	bool "Support device removal in SPL"
 	depends on SPL_DM