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esp-open-rtos/extras/timekeeping/timekeeping.c

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/*
* Basic timekeeping functions
*
* Independent of clock discipline
*/
/*-
* Copyright (c) 2018, Jeff Kletsky
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* * 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.
*
* * Neither the name of the copyright holder 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
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/reent.h>
#include <sys/time.h>
#include <sys/errno.h>
/* espressif/esp_system.h uses "bool" but fails to #include */
#include <stdbool.h>
#include <espressif/esp_system.h>
#include <time.h>
/* #define here for easier use of other system clocks */
#define GET_SYSTEM_CLOCK_US() sdk_system_get_time()
typedef uint32_t system_clock_t;
#define SYSTEM_CLOCK_WRAP_US 0x100000000LL
/*
* Define the slew rate in terms of microseconds of time to slew 1 microsecond
* This allows the use of integer arithmetic
* 2000 us to slew 1 us is 500 us of slew per sec, consistent with NTP usage
*/
#define ADJTIME_SLEW_PERIOD 2000
/*
* Try to prevent gross errors in calls to adjtime(),
* such as calling with the desired time
* NTP typically won't try to slew more than 128 ms
* At 500 ppm, can slew 1.8 seconds/hour
* A little less than what an int32_t can represent should be more than enough
* (2**31)/1e6 < 2147
*/
#define ADJTIME_MAX_SECS_ALLOWED 2000
/*
* Assume that newlib was compiled to implement tz locking
* See newlib-xtensa/newlib/libc/time/local.h
*
* __tz_lock is implemented by newlib and calls
* __tz_lock() calls __lock_acquire() which calls
* xSemaphoreTake() -- NOT RECURSIVE
* Use of __tz_lock() in applications may result in deadlock
*
* As that local.h is not available within esp-open-rtos
* replicate the definitions and provide proto here
*/
#define TZ_LOCK __tz_lock()
#define TZ_UNLOCK __tz_unlock()
extern void __tz_lock(void);
extern void __tz_unlock(void);
/*
* Multi-threading considerations
*
* While the calls related to timekeeping are generally "tight"
* there is the possiblity that the calling process will be swapped out.
* Selection of proper task priority should mitigate this
*
* taskENTER_CRITICAL() and taskEXIT_CRITICAL() might be useful
* for specialized requirements. Before considering their use
* determine if configMAX_SYSCALL_INTERRUPT_PRIORITY is enabled
* and is at a level that permits at least ticks.
* See also configMAX_API_CALL_INTERRUPT_PRIORITY
*
* TIMEKEEPING_LOCK_USE_CRITICAL doesn't make much sense
* if it prevents interrupts related to ticks!
*
* TIMEKEEPING_LOCK_USE_CRITICAL is UNTESTED
*/
#ifdef TIMEKEEPING_LOCK_USE_CRITICAL
#define TIMEKEEPING_LOCK() do {TZ_LOCK; taskENTER_CRITICAL();} while (0)
#define TIMEKEEPING_UNLOCK() do {taskEXIT_CRITICAL(); TZ_UNLOCK;} while (0)
#else
#define TIMEKEEPING_LOCK() TZ_LOCK
#define TIMEKEEPING_UNLOCK() TZ_UNLOCK
#endif
#define SIGNED_ADJTIME_SLEW_PERIOD (timekeeping_state.adjtime_delta < 0 \
? -ADJTIME_SLEW_PERIOD : ADJTIME_SLEW_PERIOD)
#define UNUSED_PARAM(X) ((void)X)
/*
* All units in timekeeping_state are microseconds
* Intentionally *signed* values as, for example, might want to reset to zero
* for a time other than when the system clock started ticking
*/
static struct
{
int64_t clock_offset;
system_clock_t last_system_clock_value;
int32_t adjtime_delta;
int64_t slew_start_time;
int64_t slew_complete_time;
} timekeeping_state;
static inline void
_reset_adjtime_state() {
/* This should only be called under TIMEKEEPING_LOCK */
timekeeping_state.adjtime_delta = 0;
timekeeping_state.slew_start_time = 0;
timekeeping_state.slew_complete_time = 0;
}
static void
_check_system_clock(void) {
/* This should only be called under TIMEKEEPING_LOCK */
system_clock_t current_system_clock;
current_system_clock = GET_SYSTEM_CLOCK_US();
if (current_system_clock < timekeeping_state.last_system_clock_value) {
timekeeping_state.clock_offset =
timekeeping_state.clock_offset + SYSTEM_CLOCK_WRAP_US;
}
timekeeping_state.last_system_clock_value = current_system_clock;
if (timekeeping_state.slew_complete_time
&& ((GET_SYSTEM_CLOCK_US() + timekeeping_state.clock_offset)
>= timekeeping_state.slew_complete_time)) {
timekeeping_state.clock_offset =
timekeeping_state.clock_offset + timekeeping_state.adjtime_delta;
_reset_adjtime_state();
}
}
int
_settimeofday_r(struct _reent *r, const struct timeval *tv, const struct timezone *tz) {
UNUSED_PARAM(tz);
int retval = 0;
system_clock_t current_system_clock;
int64_t desired_internal_clock;
/* Effectively a system call, be picky */
if (tv && (tv->tv_usec < 0 || tv->tv_usec >= 1000000 || tv->tv_sec < 0)) {
retval = -1;
r->_errno = EINVAL;
}
TIMEKEEPING_LOCK();
_check_system_clock();
if (tv && !retval) {
current_system_clock = GET_SYSTEM_CLOCK_US();
desired_internal_clock = ((int64_t) tv->tv_sec * 1000000) + tv->tv_usec;
timekeeping_state.clock_offset =
desired_internal_clock - current_system_clock;
_reset_adjtime_state();
}
TIMEKEEPING_UNLOCK();
return (retval);
}
/* "Override" the newlib definition used for gettimeofday and variants */
int
_gettimeofday_r(struct _reent *r, struct timeval *tv, void *tz) {
UNUSED_PARAM(r);
UNUSED_PARAM(tz);
system_clock_t current_system_clock;
int64_t system_plus_offset;
int64_t internal_clock;
current_system_clock = GET_SYSTEM_CLOCK_US();
TIMEKEEPING_LOCK();
_check_system_clock();
if (tv) {
system_plus_offset =
current_system_clock + timekeeping_state.clock_offset;
if (!timekeeping_state.slew_complete_time) {
internal_clock = system_plus_offset;
} else {
internal_clock =
(int64_t)(system_plus_offset
+ (system_plus_offset
- timekeeping_state.slew_start_time)
/ SIGNED_ADJTIME_SLEW_PERIOD);
}
tv->tv_sec = internal_clock / 1000000;
tv->tv_usec = internal_clock % 1000000;
}
TIMEKEEPING_UNLOCK();
return (0);
}
int
_adjtime_r(struct _reent *r, const struct timeval *delta, struct timeval *olddelta) {
int retval = 0;
system_clock_t current_system_clock;
int64_t system_plus_offset;
int32_t slew;
current_system_clock = GET_SYSTEM_CLOCK_US();
/* Effectively a system call, be picky */
if (delta && (delta->tv_usec <= -1000000 || delta->tv_usec >= 1000000
|| delta->tv_sec > ADJTIME_MAX_SECS_ALLOWED
|| delta->tv_sec < -ADJTIME_MAX_SECS_ALLOWED)) {
retval = -1;
r->_errno = EINVAL;
}
TIMEKEEPING_LOCK();
_check_system_clock();
if (!retval) {
system_plus_offset =
current_system_clock + timekeeping_state.clock_offset;
if (olddelta) {
if (timekeeping_state.slew_complete_time) {
slew = (int32_t)((timekeeping_state.slew_complete_time
- system_plus_offset)
/ SIGNED_ADJTIME_SLEW_PERIOD);
olddelta->tv_sec = slew / 1000000;
olddelta->tv_usec = slew % 1000000;
} else {
olddelta->tv_sec = 0;
olddelta->tv_usec = 0;
}
}
if (delta) {
timekeeping_state.adjtime_delta = delta->tv_sec * 1000000 + delta->tv_usec;
timekeeping_state.slew_start_time = system_plus_offset;
timekeeping_state.slew_complete_time =
timekeeping_state.slew_start_time
+ (int64_t) timekeeping_state.adjtime_delta
* SIGNED_ADJTIME_SLEW_PERIOD;
}
} /* if (!retval) */
TIMEKEEPING_UNLOCK();
return (retval);
}
int
settimeofday(const struct timeval *tv, const struct timezone *tz) {
return _settimeofday_r(_REENT, tv, tz);
}
int
adjtime(const struct timeval *delta, struct timeval *olddelta) {
return _adjtime_r(_REENT, delta, olddelta);
}
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