u-boot/include/cyclic.h
Rasmus Villemoes 50128aeb0f 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-*
2022-11-02 08:42:03 +01:00

127 lines
3.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0+ */
/*
* A general-purpose cyclic execution infrastructure, to allow "small"
* (run-time wise) functions to be executed at a specified frequency.
* Things like LED blinking or watchdog triggering are examples for such
* tasks.
*
* Copyright (C) 2022 Stefan Roese <sr@denx.de>
*/
#ifndef __cyclic_h
#define __cyclic_h
#include <linux/list.h>
#include <asm/types.h>
/**
* struct cyclic_info - Information about cyclic execution function
*
* @func: Function to call periodically
* @ctx: Context pointer to get passed to this function
* @name: Name of the cyclic function, e.g. shown in the commands
* @delay_ns: Delay is ns after which this function shall get executed
* @start_time_us: Start time in us, when this function started its execution
* @cpu_time_us: Total CPU time of this function
* @run_cnt: Counter of executions occurances
* @next_call: Next time in us, when the function shall be executed again
* @list: List node
* @already_warned: Flag that we've warned about exceeding CPU time usage
*/
struct cyclic_info {
void (*func)(void *ctx);
void *ctx;
char *name;
uint64_t delay_us;
uint64_t start_time_us;
uint64_t cpu_time_us;
uint64_t run_cnt;
uint64_t next_call;
struct hlist_node list;
bool already_warned;
};
/** Function type for cyclic functions */
typedef void (*cyclic_func_t)(void *ctx);
#if defined(CONFIG_CYCLIC)
/**
* cyclic_register - Register a new cyclic function
*
* @func: Function to call periodically
* @delay_us: Delay is us after which this function shall get executed
* @name: Cyclic function name/id
* @ctx: Context to pass to the function
* @return: pointer to cyclic_struct if OK, NULL on error
*/
struct cyclic_info *cyclic_register(cyclic_func_t func, uint64_t delay_us,
const char *name, void *ctx);
/**
* cyclic_unregister - Unregister a cyclic function
*
* @cyclic: Pointer to cyclic_struct of the function that shall be removed
* @return: 0 if OK, -ve on error
*/
int cyclic_unregister(struct cyclic_info *cyclic);
/**
* cyclic_unregister_all() - Clean up cyclic functions
*
* This removes all cyclic functions
*/
int cyclic_unregister_all(void);
/**
* cyclic_get_list() - Get cyclic list pointer
*
* Return the cyclic list pointer
*
* @return: pointer to cyclic_list
*/
struct hlist_head *cyclic_get_list(void);
/**
* cyclic_run() - Interate over all registered cyclic functions
*
* Interate over all registered cyclic functions and if the it's function
* needs to be executed, then call into these registered functions.
*/
void cyclic_run(void);
/**
* schedule() - Schedule all potentially waiting tasks
*
* Basically a wrapper for cyclic_run(), pontentially enhanced by some
* other parts, that need to get handled periodically.
*/
void schedule(void);
#else
static inline struct cyclic_info *cyclic_register(cyclic_func_t func,
uint64_t delay_us,
const char *name,
void *ctx)
{
return NULL;
}
static inline int cyclic_unregister(struct cyclic_info *cyclic)
{
return 0;
}
static inline void cyclic_run(void)
{
}
static inline void schedule(void)
{
}
static inline int cyclic_unregister_all(void)
{
return 0;
}
#endif
#endif