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 *
 *   Copyright (c) 2020 PX4 Development Team. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name PX4 nor the names of its contributors may be
 *    used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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/**
 * @file usr_hrt.c
 *
 * Userspace High-resolution timer callouts and timekeeping.
 *
 * This can be used with nuttx userspace
 *
 */

#include <px4_platform_common/px4_config.h>
#include <px4_platform_common/defines.h>
#include <px4_platform_common/posix.h>
#include <px4_platform_common/shutdown.h>

#include <sys/ioctl.h>
#include <sys/types.h>
#include <stdlib.h>
#include <stdbool.h>
#include <fcntl.h>
#include <sched.h>
#include <errno.h>

#include <assert.h>
#include <debug.h>

#include <board_config.h>
#include <drivers/drv_hrt.h>
#include <sys/boardctl.h>

static px4_task_t g_usr_hrt_task = -1;

/**
 * Fetch a never-wrapping absolute time value in microseconds from
 * some arbitrary epoch shortly after system start.
 */
hrt_abstime
hrt_absolute_time(void)
{
	hrt_abstime abstime = 0;
	boardctl(HRT_ABSOLUTE_TIME, (uintptr_t)&abstime);
	return abstime;
}

/**
 * Store the absolute time in an interrupt-safe fashion
 */
void
hrt_store_absolute_time(volatile hrt_abstime *t)
{
	irqstate_t flags = px4_enter_critical_section();
	*t = hrt_absolute_time();
	px4_leave_critical_section(flags);
}

/**
 * Event dispatcher thread
 */
int
event_thread(int argc, char *argv[])
{
	struct hrt_call *entry = NULL;

	while (1) {
		/* Wait for hrt tick */
		boardctl(HRT_WAITEVENT, (uintptr_t)&entry);

		/* HRT event received, dispatch */
		if (entry) {
			entry->usr_callout(entry->usr_arg);
		}
	}

	return 0;
}

/**
 * Request stop.
 */
bool hrt_request_stop()
{
	px4_task_delete(g_usr_hrt_task);
	return true;
}

/**
 * Initialise the high-resolution timing module.
 */
void
hrt_init(void)
{
	px4_register_shutdown_hook(hrt_request_stop);
	g_usr_hrt_task = px4_task_spawn_cmd("usr_hrt", SCHED_DEFAULT, SCHED_PRIORITY_MAX, 1000, event_thread, NULL);
}

/**
 * Call callout(arg) after interval has elapsed.
 */
void
hrt_call_after(struct hrt_call *entry, hrt_abstime delay, hrt_callout callout, void *arg)
{
	hrt_boardctl_t ioc_parm;
	ioc_parm.entry = entry;
	ioc_parm.time = delay;
	ioc_parm.callout = callout;
	ioc_parm.arg = arg;
	entry->usr_callout = callout;
	entry->usr_arg = arg;

	boardctl(HRT_CALL_AFTER, (uintptr_t)&ioc_parm);
}

/**
 * Call callout(arg) at calltime.
 */
void
hrt_call_at(struct hrt_call *entry, hrt_abstime calltime, hrt_callout callout, void *arg)
{
	hrt_boardctl_t ioc_parm;
	ioc_parm.entry = entry;
	ioc_parm.time = calltime;
	ioc_parm.interval = 0;
	ioc_parm.callout = callout;
	ioc_parm.arg = arg;
	entry->usr_callout = callout;
	entry->usr_arg = arg;

	boardctl(HRT_CALL_AT, (uintptr_t)&ioc_parm);
}

/**
 * Call callout(arg) every period.
 */
void
hrt_call_every(struct hrt_call *entry, hrt_abstime delay, hrt_abstime interval, hrt_callout callout, void *arg)
{
	hrt_boardctl_t ioc_parm;
	ioc_parm.entry = entry;
	ioc_parm.time = delay;
	ioc_parm.interval = interval;
	ioc_parm.callout = callout;
	ioc_parm.arg = arg;
	entry->usr_callout = callout;
	entry->usr_arg = arg;

	boardctl(HRT_CALL_EVERY, (uintptr_t)&ioc_parm);
}

/**
 * Remove the entry from the callout list.
 */
void
hrt_cancel(struct hrt_call *entry)
{
	boardctl(HRT_CANCEL, (uintptr_t)entry);
}

void
hrt_call_init(struct hrt_call *entry)
{
	memset(entry, 0, sizeof(*entry));
}

/**
 * If this returns true, the call has been invoked and removed from the callout list.
 *
 * Always returns false for repeating callouts.
 */
bool
hrt_called(struct hrt_call *entry)
{
	return (entry->deadline == 0);
}

latency_info_t
get_latency(uint16_t bucket_idx, uint16_t counter_idx)
{
	latency_boardctl_t latency_ioc;
	latency_ioc.bucket_idx = bucket_idx;
	latency_ioc.counter_idx = counter_idx;
	latency_ioc.latency = {0, 0};
	boardctl(HRT_GET_LATENCY, (uintptr_t)&latency_ioc);
	return latency_ioc.latency;
}

void reset_latency_counters()
{
	boardctl(HRT_RESET_LATENCY, NULL);
}