[RFC] Barebox shutdown hooks

[Herve Codina]

I try to find a way to perform some tasks on barebox leaving (ie last step of go command or boot/bootm command)
and i look at shutdown_barebox (common/startup.c)
This function is :
---- 8< -----
void shutdown_barebox(void)
{
	devices_shutdown();
#ifdef ARCH_SHUTDOWN
	arch_shutdown();
#endif
	if (board_shutdown)
		board_shutdown();
}
---- 8< -----

I have several questions :

1) Why board_shutdown is called after arch_shutdown.
arch shutdown is supposed to do stuf like disabling mmu, flushing cache, ...
Don't you think that board_shutdown should be between devices_shutdown and arch_shutdown ?

2) What about the ability to have hooks for shutdown with all resources available
For my tasks, i need devices available. What do you thing about a new "early_shutdown" called before devices_shutdown.
barebox_shutdown will become :
void shutdown_barebox(void)
{
	early_shutdown();
	devices_shutdown();
#ifdef ARCH_SHUTDOWN
	arch_shutdown();
#endif
	if (board_shutdown)
		board_shutdown();
}

for early_shutdown itself, i would give flexibility. I thing about 2 way :

2.1) register shutdown hooks
Use same mechanism as fixing up device tree :
early_shutdown_register function to register hook
and iterator calling all registered hooks in early_shutdown

2.2) exitcall
Use same mechanism as initcall functions :
Use a specific section to store exit hooks table. A macro early_exitcall (same mechanism as xxxx_initcall macro) will be used to do this.
Iterate on each hook in this section in early_shutdown (same mechanism as initcall in start_barebox).


Before doing a patch what do you think about this functionality and what way is preferred ?

Regards,
Herve