cyclic: get rid of cyclic_init()

Currently, we must call cyclic_init() at some point before
cyclic_register() becomes possible. That turns out to be somewhat
awkward, especially with SPL, and has resulted in a watchdog callback
not being registered, thus causing the board to prematurely reset.

We already rely on gd->cyclic reliably being set to NULL by the asm
code that clears all of gd. Now that the cyclic list is a hlist, and
thus an empty list is represented by a NULL head pointer, and struct
cyclic_drv has no other members, we can just as well drop a level of
indirection and put the hlist_head directly in struct
global_data. This doesn't increase the size of struct global_data,
gets rid of an early malloc(), and generates slightly smaller code.

But primarily, this avoids having to call cyclic_init() early; the cyclic
infrastructure is simply ready to register callbacks as soon as we
enter C code.

We can still end up with schedule() being called from asm very early,
so we still need to check that gd itself has been properly initialized
[*], but once it has, gd->cyclic_list is perfectly fine to access, and
will just be an empty list.

As for cyclic_uninit(), it was never really the opposite of
cyclic_init() since it didn't free the struct cyclic_drv nor set
gd->cyclic to NULL. Rename it to cyclic_unregister_all() and use that
in test/, and also insert a call at the end of the board_init_f
sequence so that gd->cyclic_list is a fresh empty list before we enter
board_init_r().

A small piece of ugliness is that I had to add a cast in
cyclic_get_list() to silence a "discards 'volatile' qualifier"
warning, but that is completely equivalent to the existing handling of
the uclass_root_s list_head member.

[*] I'm not really sure where we guarantee that the register used for
gd contains 0 until it gets explicitly initialized, but that must be
the case, otherwise testing gd for being NULL would not make much sense.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
Tested-by: Stefan Roese <sr@denx.de>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mm-venice-*

1 files changed, 3 insertions, 24 deletions

diff --git a/include/cyclic.h b/include/cyclic.h
index 4a11f9b105e..44ad3cb6b80 100644
--- a/include/cyclic.h
+++ b/include/cyclic.h
@@ -15,15 +15,6 @@
 #include <asm/types.h>
 
 /**
- * struct cyclic_drv - Cyclic driver internal data
- *
- * @cyclic_list: Cylic list node
- */
-struct cyclic_drv {
-	struct hlist_head cyclic_list;
-};
-
-/**
  * struct cyclic_info - Information about cyclic execution function
  *
  * @func: Function to call periodically
@@ -75,18 +66,11 @@ struct cyclic_info *cyclic_register(cyclic_func_t func, uint64_t delay_us,
 int cyclic_unregister(struct cyclic_info *cyclic);
 
 /**
- * cyclic_init() - Set up cyclic functions
- *
- * Init a list of cyclic functions, so that these can be added as needed
- */
-int cyclic_init(void);
-
-/**
- * cyclic_uninit() - Clean up cyclic functions
+ * cyclic_unregister_all() - Clean up cyclic functions
  *
  * This removes all cyclic functions
  */
-int cyclic_uninit(void);
+int cyclic_unregister_all(void);
 
 /**
  * cyclic_get_list() - Get cyclic list pointer
@@ -134,12 +118,7 @@ static inline void schedule(void)
 {
 }
 
-static inline int cyclic_init(void)
-{
-	return 0;
-}
-
-static inline int cyclic_uninit(void)
+static inline int cyclic_unregister_all(void)
 {
 	return 0;
 }