337 lines
11 KiB
C
337 lines
11 KiB
C
/* 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_base;
|
|
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)
|
|
* @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
|
|
* 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
|
|
* @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 {
|
|
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;
|
|
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;
|
|
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)
|
|
|
|
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 */
|