449 		 * the PIT loop below.  in pit_calibrate_tsc()
490 	 * If we were not able to read the PIT more than loopmin  in pit_calibrate_tsc()
499 	/* Calculate the PIT value */  in pit_calibrate_tsc()
506  * This reads the current MSB of the PIT counter, and
512  *  - the PIT is running at roughly 1.19MHz
518  *    or PIT for the fast calibration to work.
520  *  - with 256 PIT ticks to read the value, we have 214us to
529  *  - if the PIT is stuck, and we see *many* more reads, we
605 	 * The PIT starts counting at the next edge, so we  in quick_pit_calibrate()
608 	 * once from the PIT.  in quick_pit_calibrate()
634 			 * Check the PIT one more time to verify that  in quick_pit_calibrate()
635 			 * all TSC reads were stable wrt the PIT.  in quick_pit_calibrate()
651 	 * MSB of the PIT decrement 'i' times, and the  in quick_pit_calibrate()
664 	pr_info("Fast TSC calibration using PIT\n");  in quick_pit_calibrate()
764  * calibrate cpu using pit, hpet, and ptimer methods. They are available
779 	 * 1) PIT loop. We set the PIT Channel 2 to oneshot mode and  in pit_hpet_ptimer_calibrate_cpu()
781 	 * started the timer and wait until the PIT count down reaches  in pit_hpet_ptimer_calibrate_cpu()
785 	 * by the IO time of the PIT access, so we can detect when  in pit_hpet_ptimer_calibrate_cpu()
794 	 * disturbed values here as well. We do that around the PIT  in pit_hpet_ptimer_calibrate_cpu()
799 	/* Preset PIT loop values */  in pit_hpet_ptimer_calibrate_cpu()
809 		 * hpet/pmtimer when available. Then do the PIT  in pit_hpet_ptimer_calibrate_cpu()
819 		/* Pick the lowest PIT TSC calibration so far */  in pit_hpet_ptimer_calibrate_cpu()
849 			pr_info("PIT calibration matches %s. %d loops\n",  in pit_hpet_ptimer_calibrate_cpu()
855 		 * Check whether PIT failed more than once. This  in pit_hpet_ptimer_calibrate_cpu()
871 		/* PIT gave no useful value */  in pit_hpet_ptimer_calibrate_cpu()
872 		pr_warn("Unable to calibrate against PIT\n");  in pit_hpet_ptimer_calibrate_cpu()
893 	/* We don't have an alternative source, use the PIT calibration value */  in pit_hpet_ptimer_calibrate_cpu()
895 		pr_info("Using PIT calibration value\n");  in pit_hpet_ptimer_calibrate_cpu()
899 	/* The alternative source failed, use the PIT calibration value */  in pit_hpet_ptimer_calibrate_cpu()
901 		pr_warn("HPET/PMTIMER calibration failed. Using PIT calibration.\n");  in pit_hpet_ptimer_calibrate_cpu()
907 	 * the PIT value as we know that there are PMTIMERs around  in pit_hpet_ptimer_calibrate_cpu()
910 	pr_warn("PIT calibration deviates from %s: %lu %lu\n",  in pit_hpet_ptimer_calibrate_cpu()
912 	pr_info("Using PIT calibration value\n");  in pit_hpet_ptimer_calibrate_cpu()