mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2026-06-21 15:43:21 +02:00
Linus Torvalds
2d6d57f889
Pull timekeeping updates from Thomas Gleixner:
"Updates for NTP/timekeeping and PTP:
- Expand timekeeping snapshot mechanisms
The various snapshot functions are mostly used for PTP to collect
"atomic" snapshots of various involved clocks.
They lack support for the recently introduced AUX clocks and do not
provide the underlying counter value (e.g. TSC) to user space.
Exposing the counter value snapshot allows for better control and
steering.
Convert the hard wired ktime_get_snapshot() to take a clock ID,
which allows the caller to select the clock ID to be captured along
with CLOCK_MONONOTONIC_RAW. Additionally capture the underlying
hardware counter value and the clock source ID of the counter.
Expand the hardware based snapshot capture where devices provide a
mechanism to snapshot the hardware PTP clock and the system counter
(usually via PCI/PTM) to support AUX clocks and also provide the
captured counter value back to the caller and not only the clock
timestamps derived from it.
- Add a new optional read_snapshot() callback to clocksources
That is required to capture atomic snapshots from clocksources
which are derived from TSC with a scaling mechanism (e.g. Hyper-V,
KVMclock).
The value pair is handed back in the snapshot structure to the
callers, so they can do the necessary correlations in a more
precise way.
This touches usage sites of the affected functions and data structure
all over the tree, but stays fully backwards compatible for the
existing user space exposed interfaces. New PTP IOCTLs will provide
access to the extended functionality in later kernel versions"
* tag 'timers-ptp-2026-06-13' of gitolite.kernel.org:pub/scm/linux/kernel/git/tip/tip: (28 commits)
ptp: vmclock: Use hw_cycles from snapshot for precise TSC pairing
x86/kvmclock: Implement read_snapshot() for kvmclock clocksource
clocksource/hyperv: Implement read_snapshot() for TSC page clocksource
timekeeping: Add clocksource read_snapshot() method and hw_cycles to snapshot
ptp: Switch to ktime_get_snapshot_id() for pre/post timestamps
timekeeping: Add support for AUX clock cross timestamping
timekeeping: Remove system_device_crosststamp::sys_realtime
ALSA: hda/common: Use system_device_crosststamp::sys_systime
wifi: iwlwifi: Use system_device_crosststamp::sys_systime
ptp: Use system_device_crosststamp::sys_systime
timekeeping: Prepare for cross timestamps on arbitrary clock IDs
timekeeping: Remove ktime_get_snapshot()
virtio_rtc: Use provided clock ID for history snapshot
net/mlx5: Use provided clock ID for history snapshot
igc: Use provided clock ID for history snapshot
ice/ptp: Use provided clock ID for history snapshot
wifi: iwlwifi: Adopt PTP cross timestamps to core changes
timekeeping: Add CLOCK ID to system_device_crosststamp
timekeeping: Add system_counterval_t to struct system_device_crosststamp
timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id()
...
350 lines
12 KiB
C
350 lines
12 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/* linux/include/linux/clocksource.h
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*
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* This file contains the structure definitions for clocksources.
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*
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* If you are not a clocksource, or timekeeping code, you should
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* not be including this file!
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*/
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#ifndef _LINUX_CLOCKSOURCE_H
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#define _LINUX_CLOCKSOURCE_H
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#include <linux/types.h>
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#include <linux/timex.h>
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#include <linux/time.h>
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#include <linux/list.h>
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#include <linux/cache.h>
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#include <linux/timer.h>
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#include <linux/init.h>
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#include <linux/of.h>
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#include <linux/clocksource_ids.h>
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#include <asm/div64.h>
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#include <asm/io.h>
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struct clocksource_base;
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struct clocksource;
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struct module;
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#if defined(CONFIG_GENERIC_GETTIMEOFDAY)
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#include <asm/clocksource.h>
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#endif
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#include <vdso/clocksource.h>
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/**
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* struct clocksource_hw_snapshot - Snapshot for the underlying hardware counter of derived
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* clocksources like kvmclock or Hyper-V scaled TSC
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* @hw_cycles: The hardware counter value
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* @hw_csid: Clocksource ID of the hardware counter
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*
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* Such clocksources must implement the read_snapshot() callback and fill in the
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* hardware counter value, the clocksource ID of the hardware counter and derive
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* the actual clocksource cycles from @hw_cycles to provide an atomic snapshot
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*/
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struct clocksource_hw_snapshot {
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u64 hw_cycles;
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enum clocksource_ids hw_csid;
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};
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/**
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* struct clocksource - hardware abstraction for a free running counter
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* Provides mostly state-free accessors to the underlying hardware.
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* This is the structure used for system time.
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*
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* @read: Returns a cycle value, passes clocksource as argument
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* @mask: Bitmask for two's complement
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* subtraction of non 64 bit counters
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* @mult: Cycle to nanosecond multiplier
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* @shift: Cycle to nanosecond divisor (power of two)
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* @max_idle_ns: Maximum idle time permitted by the clocksource (nsecs)
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* @maxadj: Maximum adjustment value to mult (~11%)
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* @archdata: Optional arch-specific data
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* @max_cycles: Maximum safe cycle value which won't overflow on
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* multiplication
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* @max_raw_delta: Maximum safe delta value for negative motion detection
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* @name: Pointer to clocksource name
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* @list: List head for registration (internal)
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* @freq_khz: Clocksource frequency in khz.
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* @rating: Rating value for selection (higher is better)
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* To avoid rating inflation the following
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* list should give you a guide as to how
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* to assign your clocksource a rating
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* 1-99: Unfit for real use
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* Only available for bootup and testing purposes.
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* 100-199: Base level usability.
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* Functional for real use, but not desired.
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* 200-299: Good.
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* A correct and usable clocksource.
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* 300-399: Desired.
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* A reasonably fast and accurate clocksource.
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* 400-499: Perfect
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* The ideal clocksource. A must-use where
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* available.
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* @id: Defaults to CSID_GENERIC. The id value is captured
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* in certain snapshot functions to allow callers to
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* validate the clocksource from which the snapshot was
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* taken.
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* @flags: Flags describing special properties
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* @base: Hardware abstraction for clock on which a clocksource
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* is based
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* @read_snapshot: Extended @read() function for clocksources such as
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* kvmclock or the Hyper-V scaled TSC where the actual
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* clocksource value for timekeeping is calculated from an
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* underlying hardware counter. Returns the timekeeping
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* relevant cycle value and stores the raw value of the
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* underlying counter from which it was calculated
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* including the clocksource ID of that counter in the
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* clocksource hardware snapshot.
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* @enable: Optional function to enable the clocksource
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* @disable: Optional function to disable the clocksource
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* @suspend: Optional suspend function for the clocksource
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* @resume: Optional resume function for the clocksource
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* @mark_unstable: Optional function to inform the clocksource driver that
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* the watchdog marked the clocksource unstable
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* @tick_stable: Optional function called periodically from the watchdog
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* code to provide stable synchronization points
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* @wd_list: List head to enqueue into the watchdog list (internal)
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* @cs_last: Last clocksource value for clocksource watchdog
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* @wd_last: Last watchdog value corresponding to @cs_last
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* @owner: Module reference, must be set by clocksource in modules
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*
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* Note: This struct is not used in hotpathes of the timekeeping code
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* because the timekeeper caches the hot path fields in its own data
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* structure, so no cache line alignment is required,
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*
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* The pointer to the clocksource itself is handed to the read
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* callback. If you need extra information there you can wrap struct
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* clocksource into your own struct. Depending on the amount of
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* information you need you should consider to cache line align that
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* structure.
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*/
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struct clocksource {
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u64 (*read)(struct clocksource *cs);
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u64 mask;
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u32 mult;
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u32 shift;
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u64 max_idle_ns;
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u32 maxadj;
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u64 max_cycles;
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u64 max_raw_delta;
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const char *name;
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struct list_head list;
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u32 freq_khz;
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int rating;
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enum clocksource_ids id;
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enum vdso_clock_mode vdso_clock_mode;
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unsigned long flags;
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struct clocksource_base *base;
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u64 (*read_snapshot)(struct clocksource *cs, struct clocksource_hw_snapshot *chs);
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int (*enable)(struct clocksource *cs);
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void (*disable)(struct clocksource *cs);
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void (*suspend)(struct clocksource *cs);
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void (*resume)(struct clocksource *cs);
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void (*mark_unstable)(struct clocksource *cs);
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void (*tick_stable)(struct clocksource *cs);
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/* private: */
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#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
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/* Watchdog related data, used by the framework */
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struct list_head wd_list;
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u64 cs_last;
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u64 wd_last;
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unsigned int wd_cpu;
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#endif
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struct module *owner;
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};
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/*
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* Clock source flags bits::
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*/
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#define CLOCK_SOURCE_IS_CONTINUOUS 0x01
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#define CLOCK_SOURCE_MUST_VERIFY 0x02
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#define CLOCK_SOURCE_CALIBRATED 0x04
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#define CLOCK_SOURCE_WATCHDOG 0x10
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#define CLOCK_SOURCE_VALID_FOR_HRES 0x20
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#define CLOCK_SOURCE_UNSTABLE 0x40
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#define CLOCK_SOURCE_SUSPEND_NONSTOP 0x80
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#define CLOCK_SOURCE_RESELECT 0x100
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#define CLOCK_SOURCE_CAN_INLINE_READ 0x200
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#define CLOCK_SOURCE_HAS_COUPLED_CLOCK_EVENT 0x400
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#define CLOCK_SOURCE_WDTEST 0x800
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#define CLOCK_SOURCE_WDTEST_PERCPU 0x1000
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/* simplify initialization of mask field */
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#define CLOCKSOURCE_MASK(bits) GENMASK_ULL((bits) - 1, 0)
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static inline u32 clocksource_freq2mult(u32 freq, u32 shift_constant, u64 from)
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{
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/* freq = cyc/from
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* mult/2^shift = ns/cyc
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* mult = ns/cyc * 2^shift
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* mult = from/freq * 2^shift
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* mult = from * 2^shift / freq
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* mult = (from<<shift) / freq
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*/
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u64 tmp = ((u64)from) << shift_constant;
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tmp += freq/2; /* round for do_div */
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do_div(tmp, freq);
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return (u32)tmp;
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}
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/**
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* clocksource_khz2mult - calculates mult from khz and shift
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* @khz: Clocksource frequency in KHz
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* @shift_constant: Clocksource shift factor
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*
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* Helper functions that converts a khz counter frequency to a timsource
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* multiplier, given the clocksource shift value
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*/
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static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
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{
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return clocksource_freq2mult(khz, shift_constant, NSEC_PER_MSEC);
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}
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/**
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* clocksource_hz2mult - calculates mult from hz and shift
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* @hz: Clocksource frequency in Hz
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* @shift_constant: Clocksource shift factor
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*
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* Helper functions that converts a hz counter
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* frequency to a timsource multiplier, given the
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* clocksource shift value
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*/
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static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
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{
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return clocksource_freq2mult(hz, shift_constant, NSEC_PER_SEC);
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}
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/**
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* clocksource_cyc2ns - converts clocksource cycles to nanoseconds
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* @cycles: cycles
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* @mult: cycle to nanosecond multiplier
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* @shift: cycle to nanosecond divisor (power of two)
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*
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* Converts clocksource cycles to nanoseconds, using the given @mult and @shift.
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* The code is optimized for performance and is not intended to work
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* with absolute clocksource cycles (as those will easily overflow),
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* but is only intended to be used with relative (delta) clocksource cycles.
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*
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* XXX - This could use some mult_lxl_ll() asm optimization
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*/
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static inline s64 clocksource_cyc2ns(u64 cycles, u32 mult, u32 shift)
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{
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return ((u64) cycles * mult) >> shift;
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}
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extern int clocksource_unregister(struct clocksource*);
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extern void clocksource_touch_watchdog(void);
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extern void clocksource_suspend(void);
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extern void clocksource_resume(void);
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extern struct clocksource * __init clocksource_default_clock(void);
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extern void clocksource_mark_unstable(struct clocksource *cs);
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extern void
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clocksource_start_suspend_timing(struct clocksource *cs, u64 start_cycles);
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extern u64 clocksource_stop_suspend_timing(struct clocksource *cs, u64 now);
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extern u64
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clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
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extern void
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clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
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/*
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* Don't call __clocksource_register_scale directly, use
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* clocksource_register_hz/khz
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*/
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extern int
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__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
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extern int
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__devm_clocksource_register_scale(struct device *dev, struct clocksource *cs,
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u32 scale, u32 freq);
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/*
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* Don't call this unless you are a default clocksource
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* (AKA: jiffies) and absolutely have to.
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*/
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static inline int __clocksource_register(struct clocksource *cs)
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{
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return __clocksource_register_scale(cs, 1, 0);
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}
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static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
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{
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return __clocksource_register_scale(cs, 1, hz);
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}
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static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
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{
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return __clocksource_register_scale(cs, 1000, khz);
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}
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static inline int devm_clocksource_register_hz(struct device *dev,
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struct clocksource *cs, u32 hz)
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{
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return __devm_clocksource_register_scale(dev, cs, 1, hz);
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}
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static inline int devm_clocksource_register_khz(struct device *dev,
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struct clocksource *cs, u32 khz)
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{
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return __devm_clocksource_register_scale(dev, cs, 1000, khz);
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}
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#ifdef CONFIG_ARCH_CLOCKSOURCE_INIT
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extern void clocksource_arch_init(struct clocksource *cs);
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#else
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static inline void clocksource_arch_init(struct clocksource *cs) { }
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#endif
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extern int timekeeping_notify(struct clocksource *clock);
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extern u64 clocksource_mmio_readl_up(struct clocksource *);
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extern u64 clocksource_mmio_readl_down(struct clocksource *);
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extern u64 clocksource_mmio_readw_up(struct clocksource *);
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extern u64 clocksource_mmio_readw_down(struct clocksource *);
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extern int clocksource_mmio_init(void __iomem *, const char *,
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unsigned long, int, unsigned, u64 (*)(struct clocksource *));
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extern int clocksource_i8253_init(void);
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#define TIMER_OF_DECLARE(name, compat, fn) \
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OF_DECLARE_1_RET(timer, name, compat, fn)
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#ifdef CONFIG_TIMER_PROBE
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extern void timer_probe(void);
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#else
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static inline void timer_probe(void) {}
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#endif
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#define TIMER_ACPI_DECLARE(name, table_id, fn) \
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ACPI_DECLARE_PROBE_ENTRY(timer, name, table_id, 0, NULL, 0, fn)
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/**
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* struct clocksource_base - hardware abstraction for clock on which a clocksource
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* is based
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* @id: Defaults to CSID_GENERIC. The id value is used for conversion
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* functions which require that the current clocksource is based
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* on a clocksource_base with a particular ID in certain snapshot
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* functions to allow callers to validate the clocksource from
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* which the snapshot was taken.
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* @freq_khz: Nominal frequency of the base clock in kHz
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* @offset: Offset between the base clock and the clocksource
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* @numerator: Numerator of the clock ratio between base clock and the clocksource
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* @denominator: Denominator of the clock ratio between base clock and the clocksource
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*/
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struct clocksource_base {
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enum clocksource_ids id;
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u32 freq_khz;
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u64 offset;
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u32 numerator;
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u32 denominator;
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};
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#endif /* _LINUX_CLOCKSOURCE_H */
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