Commit 05bc6e62 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

timekeeping: Provide time getters for auxiliary clocks 



Provide interfaces similar to the ktime_get*() family which provide access
to the auxiliary clocks.

These interfaces have a boolean return value, which indicates whether the
accessed clock is valid or not.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarJohn Stultz <jstultz@google.com>
Link: https://lore.kernel.org/all/20250625183757.868342628@linutronix.de
parent 9f772948

include/linux/posix-timers.h

+5 −0
Original line number Diff line number Diff line
@@ -37,6 +37,11 @@ static inline int clockid_to_fd(const clockid_t clk) 
	return ~(clk >> 3);

}



static inline bool clockid_aux_valid(clockid_t id)

{

	return IS_ENABLED(CONFIG_POSIX_AUX_CLOCKS) && id >= CLOCK_AUX && id <= CLOCK_AUX_LAST;

}



#ifdef CONFIG_POSIX_TIMERS



#include <linux/signal_types.h>

include/linux/timekeeping.h

+11 −0
Original line number Diff line number Diff line
@@ -263,6 +263,17 @@ extern bool timekeeping_rtc_skipresume(void); 


extern void timekeeping_inject_sleeptime64(const struct timespec64 *delta);



/*

 * Auxiliary clock interfaces

 */

#ifdef CONFIG_POSIX_AUX_CLOCKS

extern bool ktime_get_aux(clockid_t id, ktime_t *kt);

extern bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt);

#else

static inline bool ktime_get_aux(clockid_t id, ktime_t *kt) { return false; }

static inline bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *kt) { return false; }

#endif



/**

 * struct system_time_snapshot - simultaneous raw/real time capture with

 *				 counter value

kernel/time/timekeeping.c

+65 −0
Original line number Diff line number Diff line
@@ -2664,6 +2664,18 @@ EXPORT_SYMBOL(hardpps); 
 */

static unsigned long aux_timekeepers;



static inline unsigned int clockid_to_tkid(unsigned int id)

{

	return TIMEKEEPER_AUX_FIRST + id - CLOCK_AUX;

}



static inline struct tk_data *aux_get_tk_data(clockid_t id)

{

	if (!clockid_aux_valid(id))

		return NULL;

	return &timekeeper_data[clockid_to_tkid(id)];

}



/* Invoked from timekeeping after a clocksource change */

static void tk_aux_update_clocksource(void)

{
@@ -2684,6 +2696,59 @@ static void tk_aux_update_clocksource(void) 
	}

}



/**

 * ktime_get_aux - Get time for a AUX clock

 * @id:	ID of the clock to read (CLOCK_AUX...)

 * @kt:	Pointer to ktime_t to store the time stamp

 *

 * Returns: True if the timestamp is valid, false otherwise

 */

bool ktime_get_aux(clockid_t id, ktime_t *kt)

{

	struct tk_data *aux_tkd = aux_get_tk_data(id);

	struct timekeeper *aux_tk;

	unsigned int seq;

	ktime_t base;

	u64 nsecs;



	WARN_ON(timekeeping_suspended);



	if (!aux_tkd)

		return false;



	aux_tk = &aux_tkd->timekeeper;

	do {

		seq = read_seqcount_begin(&aux_tkd->seq);

		if (!aux_tk->clock_valid)

			return false;



		base = ktime_add(aux_tk->tkr_mono.base, aux_tk->offs_aux);

		nsecs = timekeeping_get_ns(&aux_tk->tkr_mono);

	} while (read_seqcount_retry(&aux_tkd->seq, seq));



	*kt = ktime_add_ns(base, nsecs);

	return true;

}

EXPORT_SYMBOL_GPL(ktime_get_aux);



/**

 * ktime_get_aux_ts64 - Get time for a AUX clock

 * @id:	ID of the clock to read (CLOCK_AUX...)

 * @ts:	Pointer to timespec64 to store the time stamp

 *

 * Returns: True if the timestamp is valid, false otherwise

 */

bool ktime_get_aux_ts64(clockid_t id, struct timespec64 *ts)

{

	ktime_t now;



	if (!ktime_get_aux(id, &now))

		return false;

	*ts = ktime_to_timespec64(now);

	return true;

}

EXPORT_SYMBOL_GPL(ktime_get_aux_ts64);



static __init void tk_aux_setup(void)

{

	for (int i = TIMEKEEPER_AUX_FIRST; i <= TIMEKEEPER_AUX_LAST; i++)