diff options
Diffstat (limited to 'include/linux/clocksource.h')
| -rw-r--r-- | include/linux/clocksource.h | 386 |
1 files changed, 182 insertions, 204 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index dbbf8aa7731b..65b7c41471c3 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -1,3 +1,4 @@ +/* SPDX-License-Identifier: GPL-2.0 */ /* linux/include/linux/clocksource.h * * This file contains the structure definitions for clocksources. @@ -15,126 +16,44 @@ #include <linux/cache.h> #include <linux/timer.h> #include <linux/init.h> +#include <linux/of.h> +#include <linux/clocksource_ids.h> #include <asm/div64.h> #include <asm/io.h> -/* clocksource cycle base type */ -typedef u64 cycle_t; +struct clocksource_base; struct clocksource; struct module; -#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA +#if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \ + defined(CONFIG_GENERIC_GETTIMEOFDAY) #include <asm/clocksource.h> #endif -/** - * struct cyclecounter - hardware abstraction for a free running counter - * Provides completely state-free accessors to the underlying hardware. - * Depending on which hardware it reads, the cycle counter may wrap - * around quickly. Locking rules (if necessary) have to be defined - * by the implementor and user of specific instances of this API. - * - * @read: returns the current cycle value - * @mask: bitmask for two's complement - * subtraction of non 64 bit counters, - * see CLOCKSOURCE_MASK() helper macro - * @mult: cycle to nanosecond multiplier - * @shift: cycle to nanosecond divisor (power of two) - */ -struct cyclecounter { - cycle_t (*read)(const struct cyclecounter *cc); - cycle_t mask; - u32 mult; - u32 shift; -}; - -/** - * struct timecounter - layer above a %struct cyclecounter which counts nanoseconds - * Contains the state needed by timecounter_read() to detect - * cycle counter wrap around. Initialize with - * timecounter_init(). Also used to convert cycle counts into the - * corresponding nanosecond counts with timecounter_cyc2time(). Users - * of this code are responsible for initializing the underlying - * cycle counter hardware, locking issues and reading the time - * more often than the cycle counter wraps around. The nanosecond - * counter will only wrap around after ~585 years. - * - * @cc: the cycle counter used by this instance - * @cycle_last: most recent cycle counter value seen by - * timecounter_read() - * @nsec: continuously increasing count - */ -struct timecounter { - const struct cyclecounter *cc; - cycle_t cycle_last; - u64 nsec; -}; - -/** - * cyclecounter_cyc2ns - converts cycle counter cycles to nanoseconds - * @cc: Pointer to cycle counter. - * @cycles: Cycles - * - * XXX - This could use some mult_lxl_ll() asm optimization. Same code - * as in cyc2ns, but with unsigned result. - */ -static inline u64 cyclecounter_cyc2ns(const struct cyclecounter *cc, - cycle_t cycles) -{ - u64 ret = (u64)cycles; - ret = (ret * cc->mult) >> cc->shift; - return ret; -} - -/** - * timecounter_init - initialize a time counter - * @tc: Pointer to time counter which is to be initialized/reset - * @cc: A cycle counter, ready to be used. - * @start_tstamp: Arbitrary initial time stamp. - * - * After this call the current cycle register (roughly) corresponds to - * the initial time stamp. Every call to timecounter_read() increments - * the time stamp counter by the number of elapsed nanoseconds. - */ -extern void timecounter_init(struct timecounter *tc, - const struct cyclecounter *cc, - u64 start_tstamp); - -/** - * timecounter_read - return nanoseconds elapsed since timecounter_init() - * plus the initial time stamp - * @tc: Pointer to time counter. - * - * In other words, keeps track of time since the same epoch as - * the function which generated the initial time stamp. - */ -extern u64 timecounter_read(struct timecounter *tc); - -/** - * timecounter_cyc2time - convert a cycle counter to same - * time base as values returned by - * timecounter_read() - * @tc: Pointer to time counter. - * @cycle_tstamp: a value returned by tc->cc->read() - * - * Cycle counts that are converted correctly as long as they - * fall into the interval [-1/2 max cycle count, +1/2 max cycle count], - * with "max cycle count" == cs->mask+1. - * - * This allows conversion of cycle counter values which were generated - * in the past. - */ -extern u64 timecounter_cyc2time(struct timecounter *tc, - cycle_t cycle_tstamp); +#include <vdso/clocksource.h> /** * struct clocksource - hardware abstraction for a free running counter * Provides mostly state-free accessors to the underlying hardware. * This is the structure used for system time. * - * @name: ptr to clocksource name - * @list: list head for registration - * @rating: rating value for selection (higher is better) + * @read: Returns a cycle value, passes clocksource as argument + * @mask: Bitmask for two's complement + * subtraction of non 64 bit counters + * @mult: Cycle to nanosecond multiplier + * @shift: Cycle to nanosecond divisor (power of two) + * @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs) + * @maxadj: Maximum adjustment value to mult (~11%) + * @uncertainty_margin: Maximum uncertainty in nanoseconds per half second. + * Zero says to use default WATCHDOG_THRESHOLD. + * @archdata: Optional arch-specific data + * @max_cycles: Maximum safe cycle value which won't overflow on + * multiplication + * @max_raw_delta: Maximum safe delta value for negative motion detection + * @name: Pointer to clocksource name + * @list: List head for registration (internal) + * @freq_khz: Clocksource frequency in khz. + * @rating: Rating value for selection (higher is better) * To avoid rating inflation the following * list should give you a guide as to how * to assign your clocksource a rating @@ -149,56 +68,74 @@ extern u64 timecounter_cyc2time(struct timecounter *tc, * 400-499: Perfect * The ideal clocksource. A must-use where * available. - * @read: returns a cycle value, passes clocksource as argument - * @enable: optional function to enable the clocksource - * @disable: optional function to disable the clocksource - * @mask: bitmask for two's complement - * subtraction of non 64 bit counters - * @mult: cycle to nanosecond multiplier - * @shift: cycle to nanosecond divisor (power of two) - * @max_idle_ns: max idle time permitted by the clocksource (nsecs) - * @maxadj: maximum adjustment value to mult (~11%) - * @flags: flags describing special properties - * @archdata: arch-specific data - * @suspend: suspend function for the clocksource, if necessary - * @resume: resume function for the clocksource, if necessary - * @cycle_last: most recent cycle counter value seen by ::read() - * @owner: module reference, must be set by clocksource in modules + * @id: Defaults to CSID_GENERIC. The id value is captured + * in certain snapshot functions to allow callers to + * validate the clocksource from which the snapshot was + * taken. + * @flags: Flags describing special properties + * @base: Hardware abstraction for clock on which a clocksource + * is based + * @enable: Optional function to enable the clocksource + * @disable: Optional function to disable the clocksource + * @suspend: Optional suspend function for the clocksource + * @resume: Optional resume function for the clocksource + * @mark_unstable: Optional function to inform the clocksource driver that + * the watchdog marked the clocksource unstable + * @tick_stable: Optional function called periodically from the watchdog + * code to provide stable synchronization points + * @wd_list: List head to enqueue into the watchdog list (internal) + * @cs_last: Last clocksource value for clocksource watchdog + * @wd_last: Last watchdog value corresponding to @cs_last + * @owner: Module reference, must be set by clocksource in modules + * + * Note: This struct is not used in hotpathes of the timekeeping code + * because the timekeeper caches the hot path fields in its own data + * structure, so no cache line alignment is required, + * + * The pointer to the clocksource itself is handed to the read + * callback. If you need extra information there you can wrap struct + * clocksource into your own struct. Depending on the amount of + * information you need you should consider to cache line align that + * structure. */ struct clocksource { - /* - * Hotpath data, fits in a single cache line when the - * clocksource itself is cacheline aligned. - */ - cycle_t (*read)(struct clocksource *cs); - cycle_t cycle_last; - cycle_t mask; - u32 mult; - u32 shift; - u64 max_idle_ns; - u32 maxadj; + u64 (*read)(struct clocksource *cs); + u64 mask; + u32 mult; + u32 shift; + u64 max_idle_ns; + u32 maxadj; + u32 uncertainty_margin; #ifdef CONFIG_ARCH_CLOCKSOURCE_DATA struct arch_clocksource_data archdata; #endif - - const char *name; - struct list_head list; - int rating; - int (*enable)(struct clocksource *cs); - void (*disable)(struct clocksource *cs); - unsigned long flags; - void (*suspend)(struct clocksource *cs); - void (*resume)(struct clocksource *cs); + u64 max_cycles; + u64 max_raw_delta; + const char *name; + struct list_head list; + u32 freq_khz; + int rating; + enum clocksource_ids id; + enum vdso_clock_mode vdso_clock_mode; + unsigned long flags; + struct clocksource_base *base; + + int (*enable)(struct clocksource *cs); + void (*disable)(struct clocksource *cs); + void (*suspend)(struct clocksource *cs); + void (*resume)(struct clocksource *cs); + void (*mark_unstable)(struct clocksource *cs); + void (*tick_stable)(struct clocksource *cs); /* private: */ #ifdef CONFIG_CLOCKSOURCE_WATCHDOG /* Watchdog related data, used by the framework */ - struct list_head wd_list; - cycle_t cs_last; - cycle_t wd_last; + struct list_head wd_list; + u64 cs_last; + u64 wd_last; #endif - struct module *owner; -} ____cacheline_aligned; + struct module *owner; +}; /* * Clock source flags bits:: @@ -211,9 +148,26 @@ struct clocksource { #define CLOCK_SOURCE_UNSTABLE 0x40 #define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80 #define CLOCK_SOURCE_RESELECT 0x100 - +#define CLOCK_SOURCE_VERIFY_PERCPU 0x200 /* simplify initialization of mask field */ -#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1) +#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0) + +static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from) +{ + /* freq = cyc/from + * mult/2^shift = ns/cyc + * mult = ns/cyc * 2^shift + * mult = from/freq * 2^shift + * mult = from * 2^shift / freq + * mult = (from<<shift) / freq + */ + u64 tmp = ((u64)from) << shift_constant; + + tmp += freq/2; /* round for do_div */ + do_div(tmp, freq); + + return (u32)tmp; +} /** * clocksource_khz2mult - calculates mult from khz and shift @@ -225,19 +179,7 @@ struct clocksource { */ static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) { - /* khz = cyc/(Million ns) - * mult/2^shift = ns/cyc - * mult = ns/cyc * 2^shift - * mult = 1Million/khz * 2^shift - * mult = 1000000 * 2^shift / khz - * mult = (1000000<<shift) / khz - */ - u64 tmp = ((u64)1000000) << shift_constant; - - tmp += khz/2; /* round for do_div */ - do_div(tmp, khz); - - return (u32)tmp; + return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC); } /** @@ -251,19 +193,7 @@ static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) */ static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) { - /* hz = cyc/(Billion ns) - * mult/2^shift = ns/cyc - * mult = ns/cyc * 2^shift - * mult = 1Billion/hz * 2^shift - * mult = 1000000000 * 2^shift / hz - * mult = (1000000000<<shift) / hz - */ - u64 tmp = ((u64)1000000000) << shift_constant; - - tmp += hz/2; /* round for do_div */ - do_div(tmp, hz); - - return (u32)tmp; + return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC); } /** @@ -272,26 +202,31 @@ static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) * @mult: cycle to nanosecond multiplier * @shift: cycle to nanosecond divisor (power of two) * - * Converts cycles to nanoseconds, using the given mult and shift. + * Converts clocksource cycles to nanoseconds, using the given @mult and @shift. + * The code is optimized for performance and is not intended to work + * with absolute clocksource cycles (as those will easily overflow), + * but is only intended to be used with relative (delta) clocksource cycles. * * XXX - This could use some mult_lxl_ll() asm optimization */ -static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift) +static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift) { return ((u64) cycles * mult) >> shift; } -extern int clocksource_register(struct clocksource*); extern int clocksource_unregister(struct clocksource*); extern void clocksource_touch_watchdog(void); -extern struct clocksource* clocksource_get_next(void); -extern void clocksource_change_rating(struct clocksource *cs, int rating); extern void clocksource_suspend(void); extern void clocksource_resume(void); -extern struct clocksource * __init __weak clocksource_default_clock(void); +extern struct clocksource * __init clocksource_default_clock(void); extern void clocksource_mark_unstable(struct clocksource *cs); +extern void +clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles); +extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now); +extern u64 +clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles); extern void clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); @@ -302,7 +237,16 @@ clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec); extern int __clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); extern void -__clocksource_updatefreq_scale(struct clocksource *cs, u32 scale, u32 freq); +__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq); + +/* + * Don't call this unless you are a default clocksource + * (AKA: jiffies) and absolutely have to. + */ +static inline int __clocksource_register(struct clocksource *cs) +{ + return __clocksource_register_scale(cs, 1, 0); +} static inline int clocksource_register_hz(struct clocksource *cs, u32 hz) { @@ -314,46 +258,80 @@ static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) return __clocksource_register_scale(cs, 1000, khz); } -static inline void __clocksource_updatefreq_hz(struct clocksource *cs, u32 hz) +static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) { - __clocksource_updatefreq_scale(cs, 1, hz); + __clocksource_update_freq_scale(cs, 1, hz); } -static inline void __clocksource_updatefreq_khz(struct clocksource *cs, u32 khz) +static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz) { - __clocksource_updatefreq_scale(cs, 1000, khz); + __clocksource_update_freq_scale(cs, 1000, khz); } +#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT +extern void clocksource_arch_init(struct clocksource *cs); +#else +static inline void clocksource_arch_init(struct clocksource *cs) { } +#endif extern int timekeeping_notify(struct clocksource *clock); -extern cycle_t clocksource_mmio_readl_up(struct clocksource *); -extern cycle_t clocksource_mmio_readl_down(struct clocksource *); -extern cycle_t clocksource_mmio_readw_up(struct clocksource *); -extern cycle_t clocksource_mmio_readw_down(struct clocksource *); +extern u64 clocksource_mmio_readl_up(struct clocksource *); +extern u64 clocksource_mmio_readl_down(struct clocksource *); +extern u64 clocksource_mmio_readw_up(struct clocksource *); +extern u64 clocksource_mmio_readw_down(struct clocksource *); extern int clocksource_mmio_init(void __iomem *, const char *, - unsigned long, int, unsigned, cycle_t (*)(struct clocksource *)); + unsigned long, int, unsigned, u64 (*)(struct clocksource *)); extern int clocksource_i8253_init(void); -struct device_node; -typedef void(*clocksource_of_init_fn)(struct device_node *); -#ifdef CONFIG_CLKSRC_OF -extern void clocksource_of_init(void); +#define TIMER_OF_DECLARE(name, compat, fn) \ + OF_DECLARE_1_RET(timer, name, compat, fn) -#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ - static const struct of_device_id __clksrc_of_table_##name \ - __used __section(__clksrc_of_table) \ - = { .compatible = compat, \ - .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } +#ifdef CONFIG_TIMER_PROBE +extern void timer_probe(void); #else -static inline void clocksource_of_init(void) {} -#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \ - static const struct of_device_id __clksrc_of_table_##name \ - __attribute__((unused)) \ - = { .compatible = compat, \ - .data = (fn == (clocksource_of_init_fn)NULL) ? fn : fn } +static inline void timer_probe(void) {} #endif +#define TIMER_ACPI_DECLARE(name, table_id, fn) \ + ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn) + +static inline unsigned int clocksource_get_max_watchdog_retry(void) +{ + /* + * When system is in the boot phase or under heavy workload, there + * can be random big latencies during the clocksource/watchdog + * read, so allow retries to filter the noise latency. As the + * latency's frequency and maximum value goes up with the number of + * CPUs, scale the number of retries with the number of online + * CPUs. + */ + return (ilog2(num_online_cpus()) / 2) + 1; +} + +void clocksource_verify_percpu(struct clocksource *cs); + +/** + * struct clocksource_base - hardware abstraction for clock on which a clocksource + * is based + * @id: Defaults to CSID_GENERIC. The id value is used for conversion + * functions which require that the current clocksource is based + * on a clocksource_base with a particular ID in certain snapshot + * functions to allow callers to validate the clocksource from + * which the snapshot was taken. + * @freq_khz: Nominal frequency of the base clock in kHz + * @offset: Offset between the base clock and the clocksource + * @numerator: Numerator of the clock ratio between base clock and the clocksource + * @denominator: Denominator of the clock ratio between base clock and the clocksource + */ +struct clocksource_base { + enum clocksource_ids id; + u32 freq_khz; + u64 offset; + u32 numerator; + u32 denominator; +}; + #endif /* _LINUX_CLOCKSOURCE_H */ |