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cyclic: get rid of cyclic_init()

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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-*
This commit is contained in:
Rasmus Villemoes
2022-10-28 13:50:54 +02:00
committed by Stefan Roese
parent 2896839483
commit 50128aeb0f
6 changed files with 23 additions and 55 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
include/asm-generic/global_data.h
View File

@@ -481,9 +481,9 @@ struct global_data {
#endif
#ifdef CONFIG_CYCLIC
/**
* @cyclic: cyclic driver data
* @cyclic_list: list of registered cyclic functions
*/
struct cyclic_drv *cyclic;
struct hlist_head cyclic_list;
#endif
/**
* @dmtag_list: List of DM tags

27
include/cyclic.h
View File

@@ -14,15 +14,6 @@
#include <linux/list.h>
#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
*
@@ -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;
}