adjtime: Rewrite implementation to work for RTC and tickless kernel
Previous adjtime() implementation was limited to adjusting system timer tick period. This commit reimplements the internals to use a kernel watchdog timer. Platform-independent part of the code now works also for adjusting hires RTC and tickless timer rate. User code facing API is unchanged. Architecture code API has changed: up_adj_timer_period() is replaced by up_adjtime(). Other improvements: - Support query of remaining adjustment by passing NULL to first argument of adjtime(). This matches Linux behavior. - Improve resolution available for architecture driver, previously limited to 1 microsecond per tick. Now 1 nanosecond per second.
This commit is contained in:
Petteri Aimonen
Xiang Xiao
parent
4033018a72
commit
1825f9534c
@ -183,6 +183,16 @@ config RTC_FREQUENCY
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must be provided. If RTC_HIRES is not defined, RTC_FREQUENCY is
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assumed to be one Hz.
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config RTC_ADJTIME
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bool "RTC Adjustment Support"
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default N
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depends on RTC_HIRES
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---help---
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Enable support for adjtime() to adjust RTC run rate. The following
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interface must be provided by RTC driver:
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int up_rtc_adjtime(long ppb);
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endif # !RTC_DATETIME
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config RTC_ALARM
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@ -1644,33 +1644,23 @@ void up_secure_irq_all(bool secure);
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#endif
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/****************************************************************************
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* Function: up_adj_timer_period
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* Function: up_adjtime
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*
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* Description:
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* Adjusts timer period. This call is used when adjusting timer period as
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* defined in adjtime() function.
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*
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* Input Parameters:
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* period_inc_usec - period adjustment in usec (reset to default value
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* if 0)
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* ppb - Adjustment in parts per billion (nanoseconds per second).
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* Zero is default rate, positive value makes clock run faster
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* and negative value slower.
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*
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* Assumptions:
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* Called from within critical section or interrupt context.
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****************************************************************************/
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#ifdef CONFIG_CLOCK_ADJTIME
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void up_adj_timer_period(long long period_inc_usec);
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/****************************************************************************
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* Function: up_get_timer_period
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*
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* Description:
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* This function returns the timer period in usec.
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*
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* Input Parameters:
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* period_usec - returned timer period in usec
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*
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****************************************************************************/
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void up_get_timer_period(long long *period_usec);
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#ifdef CONFIG_ARCH_HAVE_ADJTIME
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void up_adjtime(long ppb);
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#endif
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/****************************************************************************
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@ -2606,6 +2596,29 @@ int up_rtc_getdatetime_with_subseconds(FAR struct tm *tp, FAR long *nsec);
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int up_rtc_settime(FAR const struct timespec *tp);
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#endif
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/****************************************************************************
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* Name: up_rtc_adjtime
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*
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* Description:
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* Adjust RTC frequency (running rate). Used by adjtime() when RTC is used
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* as system time source.
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*
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* Input Parameters:
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* ppb - Adjustment in parts per billion (nanoseconds per second).
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* Zero is default rate, positive value makes clock run faster
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* and negative value slower.
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*
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* Returned Value:
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* Zero (OK) on success; a negated errno value on failure.
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*
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* Assumptions:
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* Called from within a critical section.
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****************************************************************************/
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#if defined(CONFIG_RTC_HIRES) && defined(CONFIG_RTC_ADJTIME)
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int up_rtc_adjtime(long ppb);
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#endif
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/****************************************************************************
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* Name: arch_phy_irq
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*
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@ -198,23 +198,17 @@ config ARCH_HAVE_ADJTIME
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config CLOCK_ADJTIME
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bool "Support adjtime function"
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default n
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depends on ARCH_HAVE_ADJTIME
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depends on !SCHED_TICKLESS
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depends on !CLOCK_TIMEKEEPING
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depends on ARCH_HAVE_ADJTIME || RTC_ADJTIME
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---help---
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Enables usage of adjtime() interface used to correct the system time
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clock. This requires specific architecture support capable of adjusting
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system timer period.
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clock. This requires specific architecture support.
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Interfaces up_get_timer_period() and up_adj_timer_period() has to be
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defined by architecture level support.
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Adjustment can affect system timer period and/or high-resolution RTC.
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These are implemented by interfaces up_adjtime() and up_rtc_adjtime().
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This is not a POSIX interface but derives from 4.3BSD, System V.
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It is also supported for Linux compatibility.
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Currently it is not possible to use adjtime() if SCHED_TICKLESS or
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CLOCK_TIMEKEEPING is defined.
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if CLOCK_ADJTIME
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config CLOCK_ADJTIME_SLEWLIMIT_PPM
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@ -66,11 +66,6 @@ extern volatile clock_t g_system_ticks;
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extern struct timespec g_basetime;
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#endif
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#ifdef CONFIG_CLOCK_ADJTIME
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extern long long g_clk_adj_usec;
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extern long long g_clk_adj_count;
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#endif
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/****************************************************************************
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* Public Function Prototypes
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****************************************************************************/
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@ -84,12 +79,6 @@ void clock_timer(void);
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# define clock_timer()
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#endif
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#ifdef CONFIG_CLOCK_ADJTIME
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void clock_set_adjust(long long adj_usec, long long adj_count,
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FAR long long *adj_usec_old,
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FAR long long *adj_count_old);
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#endif
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int clock_abstime2ticks(clockid_t clockid,
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FAR const struct timespec *abstime,
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FAR sclock_t *ticks);
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@ -41,24 +41,102 @@
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* Pre-processor Definitions
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****************************************************************************/
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/* Current adjtime implementation uses periodic clock tick to adjust clock
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* period. Therefore this implementation will not work when tickless mode
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* is enabled by CONFIG_SCHED_TICKLESS=y
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*/
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#ifdef CONFIG_SCHED_TICKLESS
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# error CONFIG_CLOCK_ADJTIME is not supported when CONFIG_SCHED_TICKLESS \
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is enabled!
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#endif
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static struct wdog_s g_adjtime_wdog;
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static long g_adjtime_ppb;
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/* Restore default rate after adjustment period expires */
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static void adjtime_wdog_callback(wdparm_t arg)
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{
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UNUSED(arg);
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#ifdef CONFIG_ARCH_HAVE_ADJTIME
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up_adjtime(0);
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#endif
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#ifdef CONFIG_RTC_ADJTIME
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up_rtc_adjtime(0);
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#endif
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g_adjtime_ppb = 0;
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}
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/* Query remaining adjustment in microseconds */
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static long long adjtime_remaining_usec(void)
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{
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return (long long)g_adjtime_ppb
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* TICK2MSEC(wd_gettime(&g_adjtime_wdog))
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/ (MSEC_PER_SEC * NSEC_PER_USEC);
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}
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/* Start new adjustment period */
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static int adjtime_start(long long adjust_usec)
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{
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long long ppb;
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long long ppb_limit;
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irqstate_t flags;
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int ret = OK;
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/* Calculate rate adjustmend to get adjust_usec change over the
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* CONFIG_CLOCK_ADJTIME_PERIOD_MS.
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*/
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ppb = adjust_usec * NSEC_PER_USEC;
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ppb = ppb * MSEC_PER_SEC / CONFIG_CLOCK_ADJTIME_PERIOD_MS;
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/* Limit to maximum rate adjustment */
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ppb_limit = CONFIG_CLOCK_ADJTIME_SLEWLIMIT_PPM * 1000;
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if (ppb > ppb_limit)
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{
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ppb = ppb_limit;
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}
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else if (ppb < -ppb_limit)
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{
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ppb = -ppb_limit;
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}
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flags = enter_critical_section();
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/* Set new adjustment */
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g_adjtime_ppb = ppb;
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#ifdef CONFIG_ARCH_HAVE_ADJTIME
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up_adjtime(g_adjtime_ppb);
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#endif
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#ifdef CONFIG_RTC_ADJTIME
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ret = up_rtc_adjtime(g_adjtime_ppb);
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#endif
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/* Queue cancellation of adjustment after configured period */
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if (g_adjtime_ppb != 0)
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{
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wd_start(&g_adjtime_wdog, MSEC2TICK(CONFIG_CLOCK_ADJTIME_PERIOD_MS),
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adjtime_wdog_callback, 0);
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}
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else
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{
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wd_cancel(&g_adjtime_wdog);
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}
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leave_critical_section(flags);
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return ret;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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@ -100,109 +178,32 @@
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int adjtime(FAR const struct timeval *delta, FAR struct timeval *olddelta)
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{
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irqstate_t flags;
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long long adjust_usec;
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long long period_usec;
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long long adjust_usec_old;
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long long count; /* Number of cycles over which
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* we adjust the period
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*/
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long long incr; /* Period increment applied on
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* every cycle.
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*/
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long long count_old; /* Previous number of cycles over which
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* we adjust the period
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*/
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long long incr_old; /* Previous period increment applied on
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* every cycle.
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*/
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long long incr_limit;
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int is_negative;
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long long adjust_usec = 0;
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long long adjust_usec_old = 0;
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int ret = OK;
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if (!delta)
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{
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set_errno(EINVAL);
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return -1;
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}
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flags = enter_critical_section();
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adjust_usec = (long long)delta->tv_sec * USEC_PER_SEC + delta->tv_usec;
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if (adjust_usec < 0)
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{
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adjust_usec = -adjust_usec;
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is_negative = 1;
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}
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else
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{
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is_negative = 0;
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}
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/* Get period in usec. Target hardware has to provide support for
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* this function call.
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*/
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up_get_timer_period(&period_usec);
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/* Determine how much we want to adjust timer period and the number
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* of cycles over which we want to do the adjustment.
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*/
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count = (USEC_PER_MSEC * CONFIG_CLOCK_ADJTIME_PERIOD_MS) / period_usec;
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incr = adjust_usec / count;
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/* Compute maximum possible period increase and check
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* whether previously computed increase exceeds the maximum
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* one.
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*/
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incr_limit = CONFIG_CLOCK_ADJTIME_SLEWLIMIT_PPM
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/ (USEC_PER_SEC / period_usec);
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if (incr > incr_limit)
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{
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/* It does... limit computed increase and increment count. */
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incr = incr_limit;
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count = adjust_usec / incr;
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}
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/* If requested adjustment is smaller than 1 microsecond per tick,
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* adjust the count instead.
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*/
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if (adjust_usec == 0)
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{
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incr = 0;
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count = 0;
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}
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else if (incr == 0)
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{
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incr = 1;
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count = adjust_usec / incr;
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}
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if (is_negative == 1)
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{
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/* Positive or negative? */
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incr = -incr;
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}
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leave_critical_section(flags);
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/* Initialize clock adjustment and get old adjust values. */
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clock_set_adjust(incr, count, &incr_old, &count_old);
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adjust_usec_old = count_old * incr_old;
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if (olddelta)
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{
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adjust_usec_old = adjtime_remaining_usec();
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olddelta->tv_sec = adjust_usec_old / USEC_PER_SEC;
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olddelta->tv_usec = adjust_usec_old;
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}
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return OK;
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if (delta)
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{
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adjust_usec = (long long)delta->tv_sec * USEC_PER_SEC + delta->tv_usec;
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ret = adjtime_start(adjust_usec);
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}
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if (ret < 0)
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{
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set_errno(-ret);
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return -1;
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}
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else
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{
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return OK;
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}
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}
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#endif /* CONFIG_CLOCK_ADJTIME */
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@ -59,11 +59,6 @@ volatile uint32_t g_system_ticks = INITIAL_SYSTEM_TIMER_TICKS;
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struct timespec g_basetime;
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#endif
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#ifdef CONFIG_CLOCK_ADJTIME
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long long g_clk_adj_usec;
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long long g_clk_adj_count;
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#endif
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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@ -230,11 +225,6 @@ void clock_initialize(void)
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clock_inittime(NULL);
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#endif
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#if defined(CONFIG_CLOCK_ADJTIME)
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g_clk_adj_count = 0;
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g_clk_adj_usec = 0;
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#endif
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#endif
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perf_init();
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@ -420,41 +410,6 @@ skip:
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}
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#endif
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/****************************************************************************
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* Name: clock_set_adjust
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*
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* Description:
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* This function is called from adjtime() defined in clock_adjtime.c if
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* CONFIG_CLOCK_ADJTIME is enabled. It sets global variables g_clk_adj_usec
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* and g_clk_adj_count which are used for clock adjustment.
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*
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* Input Parameters:
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* adj_usec - period adjustment in usec
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* adj_count - number of clock ticks over which we apply adj_usec
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*
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****************************************************************************/
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#ifdef CONFIG_CLOCK_ADJTIME
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void clock_set_adjust(long long adj_usec, long long adj_count,
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FAR long long *adj_usec_old,
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FAR long long *adj_count_old)
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{
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/* Get old adjust values. */
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*adj_usec_old = g_clk_adj_usec;
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*adj_count_old = g_clk_adj_count;
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/* Set new adjust values. */
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g_clk_adj_usec = adj_usec;
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g_clk_adj_count = adj_count;
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/* And change timer period. */
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up_adj_timer_period(g_clk_adj_usec);
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}
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#endif
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/****************************************************************************
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* Name: clock_timer
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*
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@ -471,25 +426,5 @@ void clock_timer(void)
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/* Increment the per-tick system counter */
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g_system_ticks++;
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#ifdef CONFIG_CLOCK_ADJTIME
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/* Do we apply timer adjustment? */
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if (g_clk_adj_count > 0)
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{
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/* Yes, decrement the count each tick. */
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g_clk_adj_count--;
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/* Check if clock adjusment is finished. */
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if (g_clk_adj_count == 0)
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{
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/* Yes... reset timer period. */
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up_adj_timer_period(0);
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}
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}
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#endif
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}
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#endif
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@ -31,6 +31,7 @@
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#include <nuttx/arch.h>
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#include <nuttx/irq.h>
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#include <sys/time.h>
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#include "clock/clock.h"
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#ifdef CONFIG_CLOCK_TIMEKEEPING
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@ -55,6 +56,14 @@ int clock_settime(clockid_t clock_id, FAR const struct timespec *tp)
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struct timespec bias;
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irqstate_t flags;
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#endif
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#ifdef CONFIG_CLOCK_ADJTIME
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const struct timeval zerodelta = {
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0, 0
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};
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#endif
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int ret = OK;
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sinfo("clock_id=%d\n", clock_id);
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@ -112,8 +121,9 @@ int clock_settime(clockid_t clock_id, FAR const struct timespec *tp)
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#endif
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#ifdef CONFIG_CLOCK_ADJTIME
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g_clk_adj_count = 0;
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g_clk_adj_usec = 0;
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/* Cancel any ongoing adjustment */
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adjtime(&zerodelta, NULL);
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#endif
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leave_critical_section(flags);
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