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A hlist is headed by just a single pointer, so can only be traversed forwards, and insertions can only happen at the head (or before/after an existing list member). But each list node still consists of two pointers, so arbitrary elements can still be removed in O(1). This is precisely what we need for the cyclic_list - we never need to traverse it backwards, and the order the callbacks appear in the list should really not matter. One advantage, and the main reason for doing this switch, is that an empty list is represented by a NULL head pointer, so unlike a list_head, it does not need separate C code to initialize - a memset(,0,) of the containing structure is sufficient. This is mostly mechanical: - The iterators are updated with an h prefix, and the type of the temporary variable changed to struct hlist_node*. - Adding/removing is now just hlist_add_head (and not tail) and hlist_del(). - struct members and function return values updated. 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-*
85 lines
2.2 KiB
C
85 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* A general-purpose cyclic execution infrastructure, to allow "small"
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* (run-time wise) functions to be executed at a specified frequency.
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* Things like LED blinking or watchdog triggering are examples for such
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* tasks.
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*
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* Copyright (C) 2022 Stefan Roese <sr@denx.de>
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*/
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#include <common.h>
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#include <command.h>
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#include <cyclic.h>
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#include <div64.h>
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#include <malloc.h>
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#include <linux/delay.h>
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struct cyclic_demo_info {
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uint delay_us;
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};
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static void cyclic_demo(void *ctx)
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{
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struct cyclic_demo_info *info = ctx;
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/* Just a small dummy delay here */
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udelay(info->delay_us);
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}
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static int do_cyclic_demo(struct cmd_tbl *cmdtp, int flag, int argc,
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char *const argv[])
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{
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struct cyclic_demo_info *info;
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struct cyclic_info *cyclic;
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uint time_ms;
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if (argc < 3)
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return CMD_RET_USAGE;
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info = malloc(sizeof(struct cyclic_demo_info));
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if (!info) {
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printf("out of memory\n");
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return CMD_RET_FAILURE;
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}
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time_ms = simple_strtoul(argv[1], NULL, 0);
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info->delay_us = simple_strtoul(argv[2], NULL, 0);
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/* Register demo cyclic function */
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cyclic = cyclic_register(cyclic_demo, time_ms * 1000, "cyclic_demo",
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info);
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if (!cyclic)
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printf("Registering of cyclic_demo failed\n");
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printf("Registered function \"%s\" to be executed all %dms\n",
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"cyclic_demo", time_ms);
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return 0;
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}
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static int do_cyclic_list(struct cmd_tbl *cmdtp, int flag, int argc,
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char *const argv[])
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{
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struct cyclic_info *cyclic;
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struct hlist_node *tmp;
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u64 cnt, freq;
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hlist_for_each_entry_safe(cyclic, tmp, cyclic_get_list(), list) {
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cnt = cyclic->run_cnt * 1000000ULL * 100ULL;
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freq = lldiv(cnt, timer_get_us() - cyclic->start_time_us);
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printf("function: %s, cpu-time: %lld us, frequency: %lld.%02d times/s\n",
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cyclic->name, cyclic->cpu_time_us,
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lldiv(freq, 100), do_div(freq, 100));
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}
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return 0;
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}
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static char cyclic_help_text[] =
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"cyclic demo <cycletime_ms> <delay_us> - register cyclic demo function\n"
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"cyclic list - list cyclic functions\n";
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U_BOOT_CMD_WITH_SUBCMDS(cyclic, "Cyclic", cyclic_help_text,
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U_BOOT_SUBCMD_MKENT(demo, 3, 1, do_cyclic_demo),
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U_BOOT_SUBCMD_MKENT(list, 1, 1, do_cyclic_list));
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