kernel/time/sched_clock.c

1 // SPDX-License-Identifier: GPL-2.0
4  * counters to full 64-bit ns values.
14 #include <linux/sched/clock.h>
24  * struct clock_data - all data needed for sched_clock() (including
25  *                     registration of a new clock source)
30  * @wrap_kt:		Duration for which clock can run before wrapping.
31  * @rate:		Tick rate of the registered clock.
32  * @actual_read_sched_clock: Registered hardware level clock read function.
36  * into a single 64-byte cache line.
48 static int irqtime = -1;
55 	 * We don't need to use get_jiffies_64 on 32-bit arches here  in jiffy_sched_clock_read()
58 	return (u64)(jiffies - INITIAL_JIFFIES);  in jiffy_sched_clock_read()
93 		cyc = (rd->read_sched_clock() - rd->epoch_cyc) &  in sched_clock_noinstr()
94 		      rd->sched_clock_mask;  in sched_clock_noinstr()
95 		res = rd->epoch_ns + cyc_to_ns(cyc, rd->mult, rd->shift);  in sched_clock_noinstr()
103 	unsigned long long ns;  in sched_clock()  local
105 	ns = sched_clock_noinstr();  in sched_clock()
107 	return ns;  in sched_clock()
111  * Updating the data required to read the clock.
113  * sched_clock() will never observe mis-matched data even if called from
141 	u64 ns;  in update_sched_clock()  local
147 	ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);  in update_sched_clock()
149 	rd.epoch_ns = ns;  in update_sched_clock()
166 	u64 res, wrap, new_mask, new_epoch, cyc, ns;  in sched_clock_register()  local
178 	/* Calculate the mult/shift to convert counter ticks to ns. */  in sched_clock_register()
193 	ns = rd.epoch_ns + cyc_to_ns((cyc - rd.epoch_cyc) & rd.sched_clock_mask, rd.mult, rd.shift);  in sched_clock_register()
201 	rd.epoch_ns		= ns;  in sched_clock_register()
206 		/* update timeout for clock wrap */  in sched_clock_register()
222 	/* Calculate the ns resolution of this counter */  in sched_clock_register()
229 	if (irqtime > 0 || (irqtime == -1 && rate >= 1000000))  in sched_clock_register()
258  * Clock read function for use when the clock is suspended.
260  * This function makes it appear to sched_clock() as if the clock
281 	rd->read_sched_clock = suspended_sched_clock_read;  in sched_clock_suspend()
290 	rd->epoch_cyc = cd.actual_read_sched_clock();  in sched_clock_resume()
292 	rd->read_sched_clock = cd.actual_read_sched_clock;  in sched_clock_resume()