3  * This file contains the functions which manage clocksource drivers.
11 #include <linux/clocksource.h>
76 /*[Clocksource internal variables]---------
78  *	currently selected clocksource.
86  *	Name of the user-specified clocksource.
88 static struct clocksource *curr_clocksource;
89 static struct clocksource *suspend_clocksource;
101 static struct clocksource *watchdog;
119 static void __clocksource_change_rating(struct clocksource *cs, int rating);
145 static void __clocksource_unstable(struct clocksource *cs)  in __clocksource_unstable()
151 	 * If the clocksource is registered clocksource_watchdog_kthread() will  in __clocksource_unstable()
168  * clocksource_mark_unstable - mark clocksource unstable via watchdog
169  * @cs:		clocksource to be marked unstable
174 void clocksource_mark_unstable(struct clocksource *cs)  in clocksource_mark_unstable()
189 	struct clocksource *cs;  in clocksource_watchdog()
202 		/* Clocksource already marked unstable? */  in clocksource_watchdog()
214 		/* Clocksource initialized ? */  in clocksource_watchdog()
237 		/* Check the deviation from the watchdog clocksource. */  in clocksource_watchdog()
239 …pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is t…  in clocksource_watchdog()
266 			 * If this is not the current clocksource let  in clocksource_watchdog()
268 			 * change to high res this clocksource might  in clocksource_watchdog()
270 			 * clocksource let the tick code know about  in clocksource_watchdog()
329 	struct clocksource *cs;  in clocksource_reset_watchdog()
340 static void clocksource_enqueue_watchdog(struct clocksource *cs)  in clocksource_enqueue_watchdog()
345 		/* cs is a clocksource to be watched. */  in clocksource_enqueue_watchdog()
357 	struct clocksource *cs, *old_wd;  in clocksource_select_watchdog()
367 		/* cs is a clocksource to be watched. */  in clocksource_select_watchdog()
392 static void clocksource_dequeue_watchdog(struct clocksource *cs)  in clocksource_dequeue_watchdog()
396 			/* cs is a watched clocksource. */  in clocksource_dequeue_watchdog()
406 	struct clocksource *cs, *tmp;  in __clocksource_watchdog_kthread()
438 static bool clocksource_is_watchdog(struct clocksource *cs)  in clocksource_is_watchdog()
445 static void clocksource_enqueue_watchdog(struct clocksource *cs)  in clocksource_enqueue_watchdog()
452 static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }  in clocksource_dequeue_watchdog()
455 static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }  in clocksource_is_watchdog()
456 void clocksource_mark_unstable(struct clocksource *cs) { }  in clocksource_mark_unstable()
463 static bool clocksource_is_suspend(struct clocksource *cs)  in clocksource_is_suspend()
468 static void __clocksource_suspend_select(struct clocksource *cs)  in __clocksource_suspend_select()
471 	 * Skip the clocksource which will be stopped in suspend state.  in __clocksource_suspend_select()
477 	 * The nonstop clocksource can be selected as the suspend clocksource to  in __clocksource_suspend_select()
479 	 * interfaces to suspend the nonstop clocksource when system suspends.  in __clocksource_suspend_select()
482 		pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n",  in __clocksource_suspend_select()
492  * clocksource_suspend_select - Select the best clocksource for suspend timing
493  * @fallback:	if select a fallback clocksource
497 	struct clocksource *cs, *old_suspend;  in clocksource_suspend_select()
514  * @cs:			current clocksource from timekeeping
523  * clocksource mutex.
525 void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles)  in clocksource_start_suspend_timing()
531 	 * If current clocksource is the suspend timer, we should use the  in clocksource_start_suspend_timing()
542 		pr_warn_once("Failed to enable the non-suspend-able clocksource.\n");  in clocksource_start_suspend_timing()
551  * @cs:		current clocksource from timekeeping
556  * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource.
561  * taking the clocksource mutex.
563 u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now)  in clocksource_stop_suspend_timing()
571 	 * If current clocksource is the suspend timer, we should use the  in clocksource_stop_suspend_timing()
588 	 * Disable the suspend timer to save power if current clocksource is  in clocksource_stop_suspend_timing()
598  * clocksource_suspend - suspend the clocksource(s)
602 	struct clocksource *cs;  in clocksource_suspend()
610  * clocksource_resume - resume the clocksource(s)
614 	struct clocksource *cs;  in clocksource_resume()
637  * @cs:         Pointer to clocksource
640 static u32 clocksource_max_adjustment(struct clocksource *cs)  in clocksource_max_adjustment()
678 	 * The actual maximum number of cycles we can defer the clocksource is  in clocks_calc_max_nsecs()
697  * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles
698  * @cs:         Pointer to clocksource to be updated
701 static inline void clocksource_update_max_deferment(struct clocksource *cs)  in clocksource_update_max_deferment()
710 static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)  in clocksource_find_best()
712 	struct clocksource *cs;  in clocksource_find_best()
718 	 * We pick the clocksource with the highest rating. If oneshot  in clocksource_find_best()
719 	 * mode is active, we pick the highres valid clocksource with  in clocksource_find_best()
735 	struct clocksource *best, *cs;  in __clocksource_select()
737 	/* Find the best suitable clocksource */  in __clocksource_select()
745 	/* Check for the override clocksource. */  in __clocksource_select()
753 		 * capable clocksource if the tick code is in oneshot  in __clocksource_select()
757 			/* Override clocksource cannot be used. */  in __clocksource_select()
759 …pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/N…  in __clocksource_select()
767 				pr_info("Override clocksource %s is not currently HRT compatible - deferring\n",  in __clocksource_select()
771 			/* Override clocksource can be used. */  in __clocksource_select()
778 		pr_info("Switched to clocksource %s\n", best->name);  in __clocksource_select()
784  * clocksource_select - Select the best clocksource available
788  * Select the clocksource with the best rating, or the clocksource,
810  * Hack to avoid lots of clocksource churn at boot time.
830  * Enqueue the clocksource sorted by rating
832 static void clocksource_enqueue(struct clocksource *cs)  in clocksource_enqueue()
835 	struct clocksource *tmp;  in clocksource_enqueue()
847  * __clocksource_update_freq_scale - Used update clocksource with new freq
848  * @cs:		clocksource to be registered
849  * @scale:	Scale factor multiplied against freq to get clocksource hz
850  * @freq:	clocksource frequency (cycles per second) divided by scale
852  * This should only be called from the clocksource->enable() method.
858 void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq)  in __clocksource_update_freq_scale()
873 		 * clocksource with mask >= 40-bit and f >= 4GHz. That maps to  in __clocksource_update_freq_scale()
904 		"timekeeping: Clocksource %s might overflow on 11%% adjustment\n",  in __clocksource_update_freq_scale()
916  * @cs:		clocksource to be registered
917  * @scale:	Scale factor multiplied against freq to get clocksource hz
918  * @freq:	clocksource frequency (cycles per second) divided by scale
925 int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)  in __clocksource_register_scale()
933 		pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n",  in __clocksource_register_scale()
941 	/* Add clocksource to the clocksource list */  in __clocksource_register_scale()
957 static void __clocksource_change_rating(struct clocksource *cs, int rating)  in __clocksource_change_rating()
965  * clocksource_change_rating - Change the rating of a registered clocksource
966  * @cs:		clocksource to be changed
969 void clocksource_change_rating(struct clocksource *cs, int rating)  in clocksource_change_rating()
986  * Unbind clocksource @cs. Called with clocksource_mutex held
988 static int clocksource_unbind(struct clocksource *cs)  in clocksource_unbind()
1008 		 * Select and try to install a replacement suspend clocksource.  in clocksource_unbind()
1009 		 * If no replacement suspend clocksource, we will just let the  in clocksource_unbind()
1010 		 * clocksource go and have no suspend clocksource.  in clocksource_unbind()
1024  * clocksource_unregister - remove a registered clocksource
1025  * @cs:	clocksource to be unregistered
1027 int clocksource_unregister(struct clocksource *cs)  in clocksource_unregister()
1041  * current_clocksource_show - sysfs interface for current clocksource
1044  * @buf:	char buffer to be filled with clocksource list
1046  * Provides sysfs interface for listing current clocksource.
1079  * current_clocksource_store - interface for manually overriding clocksource
1082  * @buf:	name of override clocksource
1086  * clocksource selection.
1107  * unbind_clocksource_store - interface for manually unbinding clocksource
1113  * Takes input from sysfs interface for manually unbinding a clocksource.
1119 	struct clocksource *cs;  in unbind_clocksource_store()
1142  * available_clocksource_show - sysfs interface for listing clocksource
1145  * @buf:	char buffer to be filled with clocksource list
1153 	struct clocksource *src;  in available_clocksource_show()
1159 		 * Don't show non-HRES clocksource if the tick code is  in available_clocksource_show()
1183 ATTRIBUTE_GROUPS(clocksource);
1186 	.name = "clocksource",
1187 	.dev_name = "clocksource",
1213  * Takes a clocksource= boot argument and uses it
1214  * as the clocksource override name.
1225 __setup("clocksource=", boot_override_clocksource);
1232  * as the clocksource override name
1237 		pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n");  in boot_override_clock()
1240 	pr_warn("clock= boot option is deprecated - use clocksource=xyz\n");  in boot_override_clock()