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Diffstat (limited to 'include/linux/clocksource.h')
| -rw-r--r-- | include/linux/clocksource.h | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h new file mode 100644 index 000000000..1d42d4b17 --- /dev/null +++ b/include/linux/clocksource.h @@ -0,0 +1,297 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* linux/include/linux/clocksource.h + * + * This file contains the structure definitions for clocksources. + * + * If you are not a clocksource, or timekeeping code, you should + * not be including this file! + */ +#ifndef _LINUX_CLOCKSOURCE_H +#define _LINUX_CLOCKSOURCE_H + +#include <linux/types.h> +#include <linux/timex.h> +#include <linux/time.h> +#include <linux/list.h> +#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> + +struct clocksource; +struct module; + +#if defined(CONFIG_ARCH_CLOCKSOURCE_DATA) || \ + defined(CONFIG_GENERIC_GETTIMEOFDAY) +#include <asm/clocksource.h> +#endif + +#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. + * + * @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 + * @name: Pointer to clocksource name + * @list: List head for registration (internal) + * @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 + * 1-99: Unfit for real use + * Only available for bootup and testing purposes. + * 100-199: Base level usability. + * Functional for real use, but not desired. + * 200-299: Good. + * A correct and usable clocksource. + * 300-399: Desired. + * A reasonably fast and accurate clocksource. + * 400-499: Perfect + * The ideal clocksource. A must-use where + * available. + * @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 + * @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 { + 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 + u64 max_cycles; + const char *name; + struct list_head list; + int rating; + enum clocksource_ids id; + enum vdso_clock_mode vdso_clock_mode; + unsigned long flags; + + 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; + u64 cs_last; + u64 wd_last; +#endif + struct module *owner; +}; + +/* + * Clock source flags bits:: + */ +#define CLOCK_SOURCE_IS_CONTINUOUS 0x01 +#define CLOCK_SOURCE_MUST_VERIFY 0x02 + +#define CLOCK_SOURCE_WATCHDOG 0x10 +#define CLOCK_SOURCE_VALID_FOR_HRES 0x20 +#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) 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 + * @khz: Clocksource frequency in KHz + * @shift_constant: Clocksource shift factor + * + * Helper functions that converts a khz counter frequency to a timsource + * multiplier, given the clocksource shift value + */ +static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant) +{ + return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC); +} + +/** + * clocksource_hz2mult - calculates mult from hz and shift + * @hz: Clocksource frequency in Hz + * @shift_constant: Clocksource shift factor + * + * Helper functions that converts a hz counter + * frequency to a timsource multiplier, given the + * clocksource shift value + */ +static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant) +{ + return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC); +} + +/** + * clocksource_cyc2ns - converts clocksource cycles to nanoseconds + * @cycles: cycles + * @mult: cycle to nanosecond multiplier + * @shift: cycle to nanosecond divisor (power of two) + * + * 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(u64 cycles, u32 mult, u32 shift) +{ + return ((u64) cycles * mult) >> shift; +} + + +extern int clocksource_unregister(struct clocksource*); +extern void clocksource_touch_watchdog(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 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); + +/* + * Don't call __clocksource_register_scale directly, use + * clocksource_register_hz/khz + */ +extern int +__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq); +extern void +__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) +{ + return __clocksource_register_scale(cs, 1, hz); +} + +static inline int clocksource_register_khz(struct clocksource *cs, u32 khz) +{ + return __clocksource_register_scale(cs, 1000, khz); +} + +static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz) +{ + __clocksource_update_freq_scale(cs, 1, hz); +} + +static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 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 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, u64 (*)(struct clocksource *)); + +extern int clocksource_i8253_init(void); + +#define TIMER_OF_DECLARE(name, compat, fn) \ + OF_DECLARE_1_RET(timer, name, compat, fn) + +#ifdef CONFIG_TIMER_PROBE +extern void timer_probe(void); +#else +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) + +extern ulong max_cswd_read_retries; +void clocksource_verify_percpu(struct clocksource *cs); + +#endif /* _LINUX_CLOCKSOURCE_H */ |