linux/include/linux/clockchips.h

/* SPDX-License-Identifier: GPL-2.0 */
/*  linux/include/linux/clockchips.h
 *
 *  This file contains the structure definitions for clockchips.
 *
 *  If you are not a clockchip, or the time of day code, you should
 *  not be including this file!
 */
#ifndef _LINUX_CLOCKCHIPS_H
#define _LINUX_CLOCKCHIPS_H

#ifdef CONFIG_GENERIC_CLOCKEVENTS

# include <linux/clocksource.h>
# include <linux/cpumask_types.h>
# include <linux/ktime.h>
# include <linux/notifier.h>

struct clock_event_device;
struct module;

/*
 * Possible states of a clock event device.
 *
 * DETACHED:	Device is not used by clockevents core. Initial state or can be
 *		reached from SHUTDOWN.
 * SHUTDOWN:	Device is powered-off. Can be reached from PERIODIC or ONESHOT.
 * PERIODIC:	Device is programmed to generate events periodically. Can be
 *		reached from DETACHED or SHUTDOWN.
 * ONESHOT:	Device is programmed to generate event only once. Can be reached
 *		from DETACHED or SHUTDOWN.
 * ONESHOT_STOPPED: Device was programmed in ONESHOT mode and is temporarily
 *		    stopped.
 */
enum clock_event_state { … };

/*
 * Clock event features
 */
#define CLOCK_EVT_FEAT_PERIODIC …
#define CLOCK_EVT_FEAT_ONESHOT …
#define CLOCK_EVT_FEAT_KTIME …

/*
 * x86(64) specific (mis)features:
 *
 * - Clockevent source stops in C3 State and needs broadcast support.
 * - Local APIC timer is used as a dummy device.
 */
#define CLOCK_EVT_FEAT_C3STOP …
#define CLOCK_EVT_FEAT_DUMMY …

/*
 * Core shall set the interrupt affinity dynamically in broadcast mode
 */
#define CLOCK_EVT_FEAT_DYNIRQ …
#define CLOCK_EVT_FEAT_PERCPU …

/*
 * Clockevent device is based on a hrtimer for broadcast
 */
#define CLOCK_EVT_FEAT_HRTIMER …

/**
 * struct clock_event_device - clock event device descriptor
 * @event_handler:	Assigned by the framework to be called by the low
 *			level handler of the event source
 * @set_next_event:	set next event function using a clocksource delta
 * @set_next_ktime:	set next event function using a direct ktime value
 * @next_event:		local storage for the next event in oneshot mode
 * @max_delta_ns:	maximum delta value in ns
 * @min_delta_ns:	minimum delta value in ns
 * @mult:		nanosecond to cycles multiplier
 * @shift:		nanoseconds to cycles divisor (power of two)
 * @state_use_accessors:current state of the device, assigned by the core code
 * @features:		features
 * @retries:		number of forced programming retries
 * @set_state_periodic:	switch state to periodic
 * @set_state_oneshot:	switch state to oneshot
 * @set_state_oneshot_stopped: switch state to oneshot_stopped
 * @set_state_shutdown:	switch state to shutdown
 * @tick_resume:	resume clkevt device
 * @broadcast:		function to broadcast events
 * @min_delta_ticks:	minimum delta value in ticks stored for reconfiguration
 * @max_delta_ticks:	maximum delta value in ticks stored for reconfiguration
 * @name:		ptr to clock event name
 * @rating:		variable to rate clock event devices
 * @irq:		IRQ number (only for non CPU local devices)
 * @bound_on:		Bound on CPU
 * @cpumask:		cpumask to indicate for which CPUs this device works
 * @list:		list head for the management code
 * @owner:		module reference
 */
struct clock_event_device { … } ____cacheline_aligned;

/* Helpers to verify state of a clockevent device */
static inline bool clockevent_state_detached(struct clock_event_device *dev)
{ … }

static inline bool clockevent_state_shutdown(struct clock_event_device *dev)
{ … }

static inline bool clockevent_state_periodic(struct clock_event_device *dev)
{ … }

static inline bool clockevent_state_oneshot(struct clock_event_device *dev)
{ … }

static inline bool clockevent_state_oneshot_stopped(struct clock_event_device *dev)
{ … }

/*
 * Calculate a multiplication factor for scaled math, which is used to convert
 * nanoseconds based values to clock ticks:
 *
 * clock_ticks = (nanoseconds * factor) >> shift.
 *
 * div_sc is the rearranged equation to calculate a factor from a given clock
 * ticks / nanoseconds ratio:
 *
 * factor = (clock_ticks << shift) / nanoseconds
 */
static inline unsigned long
div_sc(unsigned long ticks, unsigned long nsec, int shift)
{ … }

/* Clock event layer functions */
extern u64 clockevent_delta2ns(unsigned long latch, struct clock_event_device *evt);
extern void clockevents_register_device(struct clock_event_device *dev);
extern int clockevents_unbind_device(struct clock_event_device *ced, int cpu);

extern void clockevents_config_and_register(struct clock_event_device *dev,
					    u32 freq, unsigned long min_delta,
					    unsigned long max_delta);

extern int clockevents_update_freq(struct clock_event_device *ce, u32 freq);

static inline void
clockevents_calc_mult_shift(struct clock_event_device *ce, u32 freq, u32 maxsec)
{ … }

extern void clockevents_suspend(void);
extern void clockevents_resume(void);

# ifdef CONFIG_GENERIC_CLOCKEVENTS_BROADCAST
#  ifdef CONFIG_ARCH_HAS_TICK_BROADCAST
extern void tick_broadcast(const struct cpumask *mask);
#  else
#define tick_broadcast …
#  endif
extern int tick_receive_broadcast(void);
# endif

# if defined(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST) && defined(CONFIG_TICK_ONESHOT)
extern void tick_setup_hrtimer_broadcast(void);
extern int tick_check_broadcast_expired(void);
# else
static __always_inline int tick_check_broadcast_expired(void) { return 0; }
static inline void tick_setup_hrtimer_broadcast(void) { }
# endif

#else /* !CONFIG_GENERIC_CLOCKEVENTS: */

static inline void clockevents_suspend(void) { }
static inline void clockevents_resume(void) { }
static __always_inline int tick_check_broadcast_expired(void) { return 0; }
static inline void tick_setup_hrtimer_broadcast(void) { }

#endif /* !CONFIG_GENERIC_CLOCKEVENTS */

#endif /* _LINUX_CLOCKCHIPS_H */