include/linux/clocksource.h

1 /* SPDX-License-Identifier: GPL-2.0 */
36  * struct clocksource - hardware abstraction for a free running counter
37  *	Provides mostly state-free accessors to the underlying hardware.
43  * @mult:		Cycle to nanosecond multiplier
46  * @maxadj:		Maximum adjustment value to mult (~11%)
49  * @archdata:		Optional arch-specific data
59  *			1-99: Unfit for real use
61  *			100-199: Base level usability.
63  *			200-299: Good.
65  *			300-399: Desired.
67  *			400-499: Perfect
68  *				The ideal clocksource. A must-use where
75  * @base:		Hardware abstraction for clock on which a clocksource
103 	u32			mult;  member
139  * Clock source flags bits::
151 #define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
156 	 *  mult/2^shift  = ns/cyc  in clocksource_freq2mult()
157 	 *  mult = ns/cyc * 2^shift  in clocksource_freq2mult()
158 	 *  mult = from/freq * 2^shift  in clocksource_freq2mult()
159 	 *  mult = from * 2^shift / freq  in clocksource_freq2mult()
160 	 *  mult = (from<<shift) / freq  in clocksource_freq2mult()
171  * clocksource_khz2mult - calculates mult from khz and shift
184  * clocksource_hz2mult - calculates mult from hz and shift
198  * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
200  * @mult:	cycle to nanosecond multiplier
203  * Converts clocksource cycles to nanoseconds, using the given @mult and @shift.
208  * XXX - This could use some mult_lxl_ll() asm optimization
210 static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)  in clocksource_cyc2ns()  argument
212 	return ((u64) cycles * mult) >> shift;  in clocksource_cyc2ns()
228 clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
230 clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
276 extern int timekeeping_notify(struct clocksource *clock);
316  * struct clocksource_base - hardware abstraction for clock on which a clocksource
323  * @freq_khz:		Nominal frequency of the base clock in kHz
324  * @offset:		Offset between the base clock and the clocksource
325  * @numerator:		Numerator of the clock ratio between base clock and the clocksource
326  * @denominator:	Denominator of the clock ratio between base clock and the clocksource