include/linux/clockchips.h

/*  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_BUILD

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

struct clock_event_device;

/* Clock event mode commands */
enum clock_event_mode {
	CLOCK_EVT_MODE_UNUSED = 0,
	CLOCK_EVT_MODE_SHUTDOWN,
	CLOCK_EVT_MODE_PERIODIC,
	CLOCK_EVT_MODE_ONESHOT,
	CLOCK_EVT_MODE_RESUME,
};

/* Clock event notification values */
enum clock_event_nofitiers {
	CLOCK_EVT_NOTIFY_ADD,
	CLOCK_EVT_NOTIFY_BROADCAST_ON,
	CLOCK_EVT_NOTIFY_BROADCAST_OFF,
	CLOCK_EVT_NOTIFY_BROADCAST_FORCE,
	CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
	CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
	CLOCK_EVT_NOTIFY_SUSPEND,
	CLOCK_EVT_NOTIFY_RESUME,
	CLOCK_EVT_NOTIFY_CPU_DYING,
	CLOCK_EVT_NOTIFY_CPU_DEAD,
};

/*
 * Clock event features
 */
#define CLOCK_EVT_FEAT_PERIODIC		0x000001
#define CLOCK_EVT_FEAT_ONESHOT		0x000002
/*
 * x86(64) specific misfeatures:
 *
 * - Clockevent source stops in C3 State and needs broadcast support.
 * - Local APIC timer is used as a dummy device.
 */
#define CLOCK_EVT_FEAT_C3STOP		0x000004
#define CLOCK_EVT_FEAT_DUMMY		0x000008

/**
 * struct clock_event_device - clock event device descriptor
 * @name:		ptr to clock event name
 * @features:		features
 * @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)
 * @rating:		variable to rate clock event devices
 * @irq:		IRQ number (only for non CPU local devices)
 * @cpumask:		cpumask to indicate for which CPUs this device works
 * @set_next_event:	set next event function
 * @set_mode:		set mode function
 * @event_handler:	Assigned by the framework to be called by the low
 *			level handler of the event source
 * @broadcast:		function to broadcast events
 * @list:		list head for the management code
 * @mode:		operating mode assigned by the management code
 * @next_event:		local storage for the next event in oneshot mode
 */
struct clock_event_device {
	const char		*name;
	unsigned int		features;
	unsigned long		max_delta_ns;
	unsigned long		min_delta_ns;
	unsigned long		mult;
	int			shift;
	int			rating;
	int			irq;
	const struct cpumask	*cpumask;
	int			(*set_next_event)(unsigned long evt,
						  struct clock_event_device *);
	void			(*set_mode)(enum clock_event_mode mode,
					    struct clock_event_device *);
	void			(*event_handler)(struct clock_event_device *);
	void			(*broadcast)(const struct cpumask *mask);
	struct list_head	list;
	enum clock_event_mode	mode;
	ktime_t			next_event;
};

/*
 * 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)
{
	uint64_t tmp = ((uint64_t)ticks) << shift;

	do_div(tmp, nsec);
	return (unsigned long) tmp;
}

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

extern void clockevents_exchange_device(struct clock_event_device *old,
					struct clock_event_device *new);
extern void clockevents_set_mode(struct clock_event_device *dev,
				 enum clock_event_mode mode);
extern int clockevents_register_notifier(struct notifier_block *nb);
extern int clockevents_program_event(struct clock_event_device *dev,
				     ktime_t expires, ktime_t now);

extern void clockevents_handle_noop(struct clock_event_device *dev);

#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern void clockevents_notify(unsigned long reason, void *arg);
#else
# define clockevents_notify(reason, arg) do { } while (0)
#endif

#else /* CONFIG_GENERIC_CLOCKEVENTS_BUILD */

#define clockevents_notify(reason, arg) do { } while (0)

#endif

#endif

#ifdef CONFIG_GENERIC_CLOCKEVENTS
extern ktime_t clockevents_get_next_event(int cpu);
#else
static inline ktime_t clockevents_get_next_event(int cpu)
{
	return (ktime_t) { .tv64 = KTIME_MAX };
}
#endif