root/include/linux/clockchips.h

INCLUDED FROM

DEFINITIONS

1. div_sc

/*  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_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;
        cpumask_t               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)(cpumask_t 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