3  * This file contains the functions which manage clocksource drivers.
11 #include <linux/clocksource.h>
78 /*[Clocksource internal variables]---------
80  *	currently selected clocksource.
88  *	Name of the user-specified clocksource.
90 static struct clocksource *curr_clocksource;
91 static struct clocksource *suspend_clocksource;
106  * clocksource surrounding a read of the clocksource being validated.
117 static struct clocksource *watchdog;
135 static void __clocksource_change_rating(struct clocksource *cs, int rating);
160 static void __clocksource_unstable(struct clocksource *cs)  in __clocksource_unstable()
166 	 * If the clocksource is registered clocksource_watchdog_kthread() will  in __clocksource_unstable()
183  * clocksource_mark_unstable - mark clocksource unstable via watchdog
184  * @cs:		clocksource to be marked unstable
189 void clocksource_mark_unstable(struct clocksource *cs)  in clocksource_mark_unstable()
208 static bool cs_watchdog_read(struct clocksource *cs, u64 *csnow, u64 *wdnow)  in cs_watchdog_read()
293 	struct clocksource *cs = (struct clocksource *)csin;  in clocksource_verify_one_cpu()
298 void clocksource_verify_percpu(struct clocksource *cs)  in clocksource_verify_percpu()
315 		pr_warn("Not enough CPUs to check clocksource '%s'.\n", cs->name);  in clocksource_verify_percpu()
319 …pr_warn("Checking clocksource %s synchronization from CPU %d to CPUs %*pbl.\n", cs->name, testcpu,…  in clocksource_verify_percpu()
342 		pr_warn("        CPUs %*pbl ahead of CPU %d for clocksource %s.\n",  in clocksource_verify_percpu()
345 		pr_warn("        CPUs %*pbl behind CPU %d for clocksource %s.\n",  in clocksource_verify_percpu()
348 		pr_warn("        CPU %d check durations %lldns - %lldns for clocksource %s.\n",  in clocksource_verify_percpu()
358 	struct clocksource *cs;  in clocksource_watchdog()
369 		/* Clocksource already marked unstable? */  in clocksource_watchdog()
382 		/* Clocksource initialized ? */  in clocksource_watchdog()
405 		/* Check the deviation from the watchdog clocksource. */  in clocksource_watchdog()
408 …pr_warn("timekeeping watchdog on CPU%d: Marking clocksource '%s' as unstable because the skew is t…  in clocksource_watchdog()
415 				pr_warn("                      '%s' is current clocksource.\n", cs->name);  in clocksource_watchdog()
417 …pr_warn("                      '%s' (not '%s') is current clocksource.\n", curr_clocksource->name,…  in clocksource_watchdog()
419 				pr_warn("                      No current clocksource.\n");  in clocksource_watchdog()
441 			 * If this is not the current clocksource let  in clocksource_watchdog()
443 			 * change to high res this clocksource might  in clocksource_watchdog()
445 			 * clocksource let the tick code know about  in clocksource_watchdog()
504 	struct clocksource *cs;  in clocksource_reset_watchdog()
515 static void clocksource_enqueue_watchdog(struct clocksource *cs)  in clocksource_enqueue_watchdog()
520 		/* cs is a clocksource to be watched. */  in clocksource_enqueue_watchdog()
532 	struct clocksource *cs, *old_wd;  in clocksource_select_watchdog()
542 		/* cs is a clocksource to be watched. */  in clocksource_select_watchdog()
567 static void clocksource_dequeue_watchdog(struct clocksource *cs)  in clocksource_dequeue_watchdog()
571 			/* cs is a watched clocksource. */  in clocksource_dequeue_watchdog()
581 	struct clocksource *cs, *tmp;  in __clocksource_watchdog_kthread()
619 static bool clocksource_is_watchdog(struct clocksource *cs)  in clocksource_is_watchdog()
626 static void clocksource_enqueue_watchdog(struct clocksource *cs)  in clocksource_enqueue_watchdog()
633 static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }  in clocksource_dequeue_watchdog()
636 static bool clocksource_is_watchdog(struct clocksource *cs) { return false; }  in clocksource_is_watchdog()
637 void clocksource_mark_unstable(struct clocksource *cs) { }  in clocksource_mark_unstable()
644 static bool clocksource_is_suspend(struct clocksource *cs)  in clocksource_is_suspend()
649 static void __clocksource_suspend_select(struct clocksource *cs)  in __clocksource_suspend_select()
652 	 * Skip the clocksource which will be stopped in suspend state.  in __clocksource_suspend_select()
658 	 * The nonstop clocksource can be selected as the suspend clocksource to  in __clocksource_suspend_select()
660 	 * interfaces to suspend the nonstop clocksource when system suspends.  in __clocksource_suspend_select()
663 		pr_warn("Nonstop clocksource %s should not supply suspend/resume interfaces\n",  in __clocksource_suspend_select()
673  * clocksource_suspend_select - Select the best clocksource for suspend timing
674  * @fallback:	if select a fallback clocksource
678 	struct clocksource *cs, *old_suspend;  in clocksource_suspend_select()
695  * @cs:			current clocksource from timekeeping
704  * clocksource mutex.
706 void clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles)  in clocksource_start_suspend_timing()
712 	 * If current clocksource is the suspend timer, we should use the  in clocksource_start_suspend_timing()
723 		pr_warn_once("Failed to enable the non-suspend-able clocksource.\n");  in clocksource_start_suspend_timing()
732  * @cs:		current clocksource from timekeeping
737  * Returns nanoseconds since suspend started, 0 if no usable suspend clocksource.
742  * taking the clocksource mutex.
744 u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 cycle_now)  in clocksource_stop_suspend_timing()
752 	 * If current clocksource is the suspend timer, we should use the  in clocksource_stop_suspend_timing()
769 	 * Disable the suspend timer to save power if current clocksource is  in clocksource_stop_suspend_timing()
779  * clocksource_suspend - suspend the clocksource(s)
783 	struct clocksource *cs;  in clocksource_suspend()
791  * clocksource_resume - resume the clocksource(s)
795 	struct clocksource *cs;  in clocksource_resume()
818  * @cs:         Pointer to clocksource
821 static u32 clocksource_max_adjustment(struct clocksource *cs)  in clocksource_max_adjustment()
859 	 * The actual maximum number of cycles we can defer the clocksource is  in clocks_calc_max_nsecs()
878  * clocksource_update_max_deferment - Updates the clocksource max_idle_ns & max_cycles
879  * @cs:         Pointer to clocksource to be updated
882 static inline void clocksource_update_max_deferment(struct clocksource *cs)  in clocksource_update_max_deferment()
889 static struct clocksource *clocksource_find_best(bool oneshot, bool skipcur)  in clocksource_find_best()
891 	struct clocksource *cs;  in clocksource_find_best()
897 	 * We pick the clocksource with the highest rating. If oneshot  in clocksource_find_best()
898 	 * mode is active, we pick the highres valid clocksource with  in clocksource_find_best()
914 	struct clocksource *best, *cs;  in __clocksource_select()
916 	/* Find the best suitable clocksource */  in __clocksource_select()
924 	/* Check for the override clocksource. */  in __clocksource_select()
932 		 * capable clocksource if the tick code is in oneshot  in __clocksource_select()
936 			/* Override clocksource cannot be used. */  in __clocksource_select()
938 …pr_warn("Override clocksource %s is unstable and not HRT compatible - cannot switch while in HRT/N…  in __clocksource_select()
946 				pr_info("Override clocksource %s is not currently HRT compatible - deferring\n",  in __clocksource_select()
950 			/* Override clocksource can be used. */  in __clocksource_select()
957 		pr_info("Switched to clocksource %s\n", best->name);  in __clocksource_select()
963  * clocksource_select - Select the best clocksource available
967  * Select the clocksource with the best rating, or the clocksource,
983  * Hack to avoid lots of clocksource churn at boot time.
1003  * Enqueue the clocksource sorted by rating
1005 static void clocksource_enqueue(struct clocksource *cs)  in clocksource_enqueue()
1008 	struct clocksource *tmp;  in clocksource_enqueue()
1020  * __clocksource_update_freq_scale - Used update clocksource with new freq
1021  * @cs:		clocksource to be registered
1022  * @scale:	Scale factor multiplied against freq to get clocksource hz
1023  * @freq:	clocksource frequency (cycles per second) divided by scale
1025  * This should only be called from the clocksource->enable() method.
1031 void __clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq)  in __clocksource_update_freq_scale()
1046 		 * clocksource with mask >= 40-bit and f >= 4GHz. That maps to  in __clocksource_update_freq_scale()
1097 		"timekeeping: Clocksource %s might overflow on 11%% adjustment\n",  in __clocksource_update_freq_scale()
1109  * @cs:		clocksource to be registered
1110  * @scale:	Scale factor multiplied against freq to get clocksource hz
1111  * @freq:	clocksource frequency (cycles per second) divided by scale
1118 int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq)  in __clocksource_register_scale()
1128 		pr_warn("clocksource %s registered with invalid VDSO mode %d. Disabling VDSO support.\n",  in __clocksource_register_scale()
1136 	/* Add clocksource to the clocksource list */  in __clocksource_register_scale()
1152 static void __clocksource_change_rating(struct clocksource *cs, int rating)  in __clocksource_change_rating()
1160  * clocksource_change_rating - Change the rating of a registered clocksource
1161  * @cs:		clocksource to be changed
1164 void clocksource_change_rating(struct clocksource *cs, int rating)  in clocksource_change_rating()
1181  * Unbind clocksource @cs. Called with clocksource_mutex held
1183 static int clocksource_unbind(struct clocksource *cs)  in clocksource_unbind()
1203 		 * Select and try to install a replacement suspend clocksource.  in clocksource_unbind()
1204 		 * If no replacement suspend clocksource, we will just let the  in clocksource_unbind()
1205 		 * clocksource go and have no suspend clocksource.  in clocksource_unbind()
1219  * clocksource_unregister - remove a registered clocksource
1220  * @cs:	clocksource to be unregistered
1222 int clocksource_unregister(struct clocksource *cs)  in clocksource_unregister()
1236  * current_clocksource_show - sysfs interface for current clocksource
1239  * @buf:	char buffer to be filled with clocksource list
1241  * Provides sysfs interface for listing current clocksource.
1274  * current_clocksource_store - interface for manually overriding clocksource
1277  * @buf:	name of override clocksource
1281  * clocksource selection.
1302  * unbind_clocksource_store - interface for manually unbinding clocksource
1308  * Takes input from sysfs interface for manually unbinding a clocksource.
1314 	struct clocksource *cs;  in unbind_clocksource_store()
1337  * available_clocksource_show - sysfs interface for listing clocksource
1340  * @buf:	char buffer to be filled with clocksource list
1348 	struct clocksource *src;  in available_clocksource_show()
1354 		 * Don't show non-HRES clocksource if the tick code is  in available_clocksource_show()
1378 ATTRIBUTE_GROUPS(clocksource);
1381 	.name = "clocksource",
1382 	.dev_name = "clocksource",
1408  * Takes a clocksource= boot argument and uses it
1409  * as the clocksource override name.
1420 __setup("clocksource=", boot_override_clocksource);
1427  * as the clocksource override name
1432 		pr_warn("clock=pmtmr is deprecated - use clocksource=acpi_pm\n");  in boot_override_clock()
1435 	pr_warn("clock= boot option is deprecated - use clocksource=xyz\n");  in boot_override_clock()