linux/drivers/isdn/mISDN/clock.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright 2008  by Andreas Eversberg <[email protected]>
 *
 * Quick API description:
 *
 * A clock source registers using mISDN_register_clock:
 *	name = text string to name clock source
 *	priority = value to priorize clock sources (0 = default)
 *	ctl = callback function to enable/disable clock source
 *	priv = private pointer of clock source
 *	return = pointer to clock source structure;
 *
 * Note: Callback 'ctl' can be called before mISDN_register_clock returns!
 *       Also it can be called during mISDN_unregister_clock.
 *
 * A clock source calls mISDN_clock_update with given samples elapsed, if
 * enabled. If function call is delayed, tv must be set with the timestamp
 * of the actual event.
 *
 * A clock source unregisters using mISDN_unregister_clock.
 *
 * To get current clock, call mISDN_clock_get. The signed short value
 * counts the number of samples since. Time since last clock event is added.
 */

#include <linux/slab.h>
#include <linux/types.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/ktime.h>
#include <linux/mISDNif.h>
#include <linux/export.h>
#include "core.h"

static u_int *debug;
static LIST_HEAD(iclock_list);
static DEFINE_RWLOCK(iclock_lock);
static u16 iclock_count;		/* counter of last clock */
static ktime_t iclock_timestamp;	/* time stamp of last clock */
static int iclock_timestamp_valid;	/* already received one timestamp */
static struct mISDNclock *iclock_current;

void
mISDN_init_clock(u_int *dp)
{ … }

static void
select_iclock(void)
{ … }

struct mISDNclock
*mISDN_register_clock(char *name, int pri, clockctl_func_t *ctl, void *priv)
{ … }
EXPORT_SYMBOL(…);

void
mISDN_unregister_clock(struct mISDNclock *iclock)
{ … }
EXPORT_SYMBOL(…);

void
mISDN_clock_update(struct mISDNclock *iclock, int samples, ktime_t *timestamp)
{ … }
EXPORT_SYMBOL(…);

unsigned short
mISDN_clock_get(void)
{ … }
EXPORT_SYMBOL(…);