1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * A general-purpose cyclic execution infrastructure, to allow "small"
4 * (run-time wise) functions to be executed at a specified frequency.
5 * Things like LED blinking or watchdog triggering are examples for such
6 * tasks.
7 *
8 * Copyright (C) 2022 Stefan Roese <sr@denx.de>
9 */
10
11#include <cyclic.h>
12#include <log.h>
13#include <malloc.h>
14#include <time.h>
15#include <linux/errno.h>
16#include <linux/list.h>
17#include <asm/global_data.h>
18
19DECLARE_GLOBAL_DATA_PTR;
20
21void hw_watchdog_reset(void);
22
23struct hlist_head *cyclic_get_list(void)
24{
25	/* Silence "discards 'volatile' qualifier" warning. */
26	return (struct hlist_head *)&gd->cyclic_list;
27}
28
29struct cyclic_info *cyclic_register(cyclic_func_t func, uint64_t delay_us,
30				    const char *name, void *ctx)
31{
32	struct cyclic_info *cyclic;
33
34	cyclic = calloc(1, sizeof(struct cyclic_info));
35	if (!cyclic) {
36		pr_debug("Memory allocation error\n");
37		return NULL;
38	}
39
40	/* Store values in struct */
41	cyclic->func = func;
42	cyclic->ctx = ctx;
43	cyclic->name = strdup(name);
44	cyclic->delay_us = delay_us;
45	cyclic->start_time_us = timer_get_us();
46	hlist_add_head(&cyclic->list, cyclic_get_list());
47
48	return cyclic;
49}
50
51int cyclic_unregister(struct cyclic_info *cyclic)
52{
53	hlist_del(&cyclic->list);
54	free(cyclic);
55
56	return 0;
57}
58
59void cyclic_run(void)
60{
61	struct cyclic_info *cyclic;
62	struct hlist_node *tmp;
63	uint64_t now, cpu_time;
64
65	/* Prevent recursion */
66	if (gd->flags & GD_FLG_CYCLIC_RUNNING)
67		return;
68
69	gd->flags |= GD_FLG_CYCLIC_RUNNING;
70	hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
71		/*
72		 * Check if this cyclic function needs to get called, e.g.
73		 * do not call the cyclic func too often
74		 */
75		now = timer_get_us();
76		if (time_after_eq64(now, cyclic->next_call)) {
77			/* Call cyclic function and account it's cpu-time */
78			cyclic->next_call = now + cyclic->delay_us;
79			cyclic->func(cyclic->ctx);
80			cyclic->run_cnt++;
81			cpu_time = timer_get_us() - now;
82			cyclic->cpu_time_us += cpu_time;
83
84			/* Check if cpu-time exceeds max allowed time */
85			if ((cpu_time > CONFIG_CYCLIC_MAX_CPU_TIME_US) &&
86			    (!cyclic->already_warned)) {
87				pr_err("cyclic function %s took too long: %lldus vs %dus max\n",
88				       cyclic->name, cpu_time,
89				       CONFIG_CYCLIC_MAX_CPU_TIME_US);
90
91				/*
92				 * Don't disable this function, just warn once
93				 * about this exceeding CPU time usage
94				 */
95				cyclic->already_warned = true;
96			}
97		}
98	}
99	gd->flags &= ~GD_FLG_CYCLIC_RUNNING;
100}
101
102void schedule(void)
103{
104	/* The HW watchdog is not integrated into the cyclic IF (yet) */
105	if (IS_ENABLED(CONFIG_HW_WATCHDOG))
106		hw_watchdog_reset();
107
108	/*
109	 * schedule() might get called very early before the cyclic IF is
110	 * ready. Make sure to only call cyclic_run() when it's initalized.
111	 */
112	if (gd)
113		cyclic_run();
114}
115
116int cyclic_unregister_all(void)
117{
118	struct cyclic_info *cyclic;
119	struct hlist_node *tmp;
120
121	hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list)
122		cyclic_unregister(cyclic);
123
124	return 0;
125}
126