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"Das U-Boot" Source Tree
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#include <u-boot/schedule.h>
19
20DECLARE_GLOBAL_DATA_PTR;
21
22void hw_watchdog_reset(void);
23
24struct hlist_head *cyclic_get_list(void)
25{
26 /* Silence "discards 'volatile' qualifier" warning. */
27 return (struct hlist_head *)&gd->cyclic_list;
28}
29
30void cyclic_register(struct cyclic_info *cyclic, cyclic_func_t func,
31 uint64_t delay_us, const char *name)
32{
33 memset(cyclic, 0, sizeof(*cyclic));
34
35 /* Store values in struct */
36 cyclic->func = func;
37 cyclic->name = name;
38 cyclic->delay_us = delay_us;
39 cyclic->start_time_us = get_timer_us(0);
40 hlist_add_head(&cyclic->list, cyclic_get_list());
41}
42
43void cyclic_unregister(struct cyclic_info *cyclic)
44{
45 hlist_del(&cyclic->list);
46}
47
48static void cyclic_run(void)
49{
50 struct cyclic_info *cyclic;
51 struct hlist_node *tmp;
52 uint64_t now, cpu_time;
53
54 /* Prevent recursion */
55 if (gd->flags & GD_FLG_CYCLIC_RUNNING)
56 return;
57
58 gd->flags |= GD_FLG_CYCLIC_RUNNING;
59 hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
60 /*
61 * Check if this cyclic function needs to get called, e.g.
62 * do not call the cyclic func too often
63 */
64 now = get_timer_us(0);
65 if (time_after_eq64(now, cyclic->next_call)) {
66 /* Call cyclic function and account it's cpu-time */
67 cyclic->next_call = now + cyclic->delay_us;
68 cyclic->func(cyclic);
69 cyclic->run_cnt++;
70 cpu_time = get_timer_us(0) - now;
71 cyclic->cpu_time_us += cpu_time;
72
73 /* Check if cpu-time exceeds max allowed time */
74 if ((cpu_time > CONFIG_CYCLIC_MAX_CPU_TIME_US) &&
75 (!cyclic->already_warned)) {
76 pr_err("cyclic function %s took too long: %lldus vs %dus max\n",
77 cyclic->name, cpu_time,
78 CONFIG_CYCLIC_MAX_CPU_TIME_US);
79
80 /*
81 * Don't disable this function, just warn once
82 * about this exceeding CPU time usage
83 */
84 cyclic->already_warned = true;
85 }
86 }
87 }
88 gd->flags &= ~GD_FLG_CYCLIC_RUNNING;
89}
90
91void schedule(void)
92{
93 /* The HW watchdog is not integrated into the cyclic IF (yet) */
94 if (IS_ENABLED(CONFIG_HW_WATCHDOG))
95 hw_watchdog_reset();
96
97 /*
98 * schedule() might get called very early before the cyclic IF is
99 * ready. Make sure to only call cyclic_run() when it's initalized.
100 */
101 if (gd)
102 cyclic_run();
103}
104
105int cyclic_unregister_all(void)
106{
107 struct cyclic_info *cyclic;
108 struct hlist_node *tmp;
109
110 hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list)
111 cyclic_unregister(cyclic);
112
113 return 0;
114}