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 #include <uthread.h>
20
21 DECLARE_GLOBAL_DATA_PTR;
22
23 void hw_watchdog_reset(void);
24
cyclic_get_list(void)25 struct hlist_head *cyclic_get_list(void)
26 {
27 /* Silence "discards 'volatile' qualifier" warning. */
28 return (struct hlist_head *)&gd->cyclic_list;
29 }
30
cyclic_is_registered(const struct cyclic_info * cyclic)31 static bool cyclic_is_registered(const struct cyclic_info *cyclic)
32 {
33 const struct cyclic_info *c;
34
35 hlist_for_each_entry(c, cyclic_get_list(), list) {
36 if (c == cyclic)
37 return true;
38 }
39
40 return false;
41 }
42
cyclic_register(struct cyclic_info * cyclic,cyclic_func_t func,uint64_t delay_us,const char * name)43 void cyclic_register(struct cyclic_info *cyclic, cyclic_func_t func,
44 uint64_t delay_us, const char *name)
45 {
46 cyclic_unregister(cyclic);
47
48 memset(cyclic, 0, sizeof(*cyclic));
49
50 /* Store values in struct */
51 cyclic->func = func;
52 cyclic->name = name;
53 cyclic->delay_us = delay_us;
54 cyclic->start_time_us = get_timer_us(0);
55 hlist_add_head(&cyclic->list, cyclic_get_list());
56 }
57
cyclic_unregister(struct cyclic_info * cyclic)58 void cyclic_unregister(struct cyclic_info *cyclic)
59 {
60 if (!cyclic_is_registered(cyclic))
61 return;
62
63 hlist_del(&cyclic->list);
64 }
65
cyclic_run(void)66 static void cyclic_run(void)
67 {
68 struct cyclic_info *cyclic;
69 struct hlist_node *tmp;
70 uint64_t now, cpu_time;
71
72 /* Prevent recursion */
73 if (gd->flags & GD_FLG_CYCLIC_RUNNING)
74 return;
75
76 gd->flags |= GD_FLG_CYCLIC_RUNNING;
77 hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
78 /*
79 * Check if this cyclic function needs to get called, e.g.
80 * do not call the cyclic func too often
81 */
82 now = get_timer_us(0);
83 if (time_after_eq64(now, cyclic->next_call)) {
84 /* Call cyclic function and account it's cpu-time */
85 cyclic->next_call = now + cyclic->delay_us;
86 cyclic->func(cyclic);
87 cyclic->run_cnt++;
88 cpu_time = get_timer_us(0) - now;
89 cyclic->cpu_time_us += cpu_time;
90
91 /* Check if cpu-time exceeds max allowed time */
92 if ((cpu_time > CONFIG_CYCLIC_MAX_CPU_TIME_US) &&
93 (!cyclic->already_warned)) {
94 pr_err("cyclic function %s took too long: %lldus vs %dus max\n",
95 cyclic->name, cpu_time,
96 CONFIG_CYCLIC_MAX_CPU_TIME_US);
97
98 /*
99 * Don't disable this function, just warn once
100 * about this exceeding CPU time usage
101 */
102 cyclic->already_warned = true;
103 }
104 }
105 }
106 gd->flags &= ~GD_FLG_CYCLIC_RUNNING;
107 }
108
schedule(void)109 void schedule(void)
110 {
111 /* The HW watchdog is not integrated into the cyclic IF (yet) */
112 if (IS_ENABLED(CONFIG_HW_WATCHDOG))
113 hw_watchdog_reset();
114
115 /*
116 * schedule() might get called very early before the cyclic IF is
117 * ready. Make sure to only call cyclic_run() when it's initalized.
118 */
119 if (gd)
120 cyclic_run();
121
122 uthread_schedule();
123 }
124
cyclic_unregister_all(void)125 int cyclic_unregister_all(void)
126 {
127 struct cyclic_info *cyclic;
128 struct hlist_node *tmp;
129
130 hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list)
131 cyclic_unregister(cyclic);
132
133 return 0;
134 }
135