[mirror_ubuntu-bionic-kernel.git] / drivers / isdn / mISDN / clock.c

/*
 * Copyright 2008  by Andreas Eversberg <andreas@eversberg.eu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * 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/types.h>
#include <linux/stddef.h>
#include <linux/spinlock.h>
#include <linux/mISDNif.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 struct timeval iclock_tv;	/* time stamp of last clock */
static int iclock_tv_valid;		/* already received one timestamp */
static struct mISDNclock *iclock_current;

void
mISDN_init_clock(u_int *dp)
{
	debug = dp;
	do_gettimeofday(&iclock_tv);
}

static void
select_iclock(void)
{
	struct mISDNclock *iclock, *bestclock = NULL, *lastclock = NULL;
	int pri = -128;

	list_for_each_entry(iclock, &iclock_list, list) {
		if (iclock->pri > pri) {
			pri = iclock->pri;
			bestclock = iclock;
		}
		if (iclock_current == iclock)
			lastclock = iclock;
	}
	if (lastclock && bestclock != lastclock) {
		/* last used clock source still exists but changes, disable */
		if (*debug & DEBUG_CLOCK)
			printk(KERN_DEBUG "Old clock source '%s' disable.\n",
				lastclock->name);
		lastclock->ctl(lastclock->priv, 0);
	}
	if (bestclock && bestclock != iclock_current) {
		/* new clock source selected, enable */
		if (*debug & DEBUG_CLOCK)
			printk(KERN_DEBUG "New clock source '%s' enable.\n",
				bestclock->name);
		bestclock->ctl(bestclock->priv, 1);
	}
	if (bestclock != iclock_current) {
		/* no clock received yet */
		iclock_tv_valid = 0;
	}
	iclock_current = bestclock;
}

struct mISDNclock
*mISDN_register_clock(char *name, int pri, clockctl_func_t *ctl, void *priv)
{
	u_long			flags;
	struct mISDNclock	*iclock;

	if (*debug & (DEBUG_CORE | DEBUG_CLOCK))
		printk(KERN_DEBUG "%s: %s %d\n", __func__, name, pri);
	iclock = kzalloc(sizeof(struct mISDNclock), GFP_ATOMIC);
	if (!iclock) {
		printk(KERN_ERR "%s: No memory for clock entry.\n", __func__);
		return NULL;
	}
	strncpy(iclock->name, name, sizeof(iclock->name)-1);
	iclock->pri = pri;
	iclock->priv = priv;
	iclock->ctl = ctl;
	write_lock_irqsave(&iclock_lock, flags);
	list_add_tail(&iclock->list, &iclock_list);
	select_iclock();
	write_unlock_irqrestore(&iclock_lock, flags);
	return iclock;
}
EXPORT_SYMBOL(mISDN_register_clock);

void
mISDN_unregister_clock(struct mISDNclock *iclock)
{
	u_long	flags;

	if (*debug & (DEBUG_CORE | DEBUG_CLOCK))
		printk(KERN_DEBUG "%s: %s %d\n", __func__, iclock->name,
			iclock->pri);
	write_lock_irqsave(&iclock_lock, flags);
	if (iclock_current == iclock) {
		if (*debug & DEBUG_CLOCK)
			printk(KERN_DEBUG
				"Current clock source '%s' unregisters.\n",
				iclock->name);
		iclock->ctl(iclock->priv, 0);
	}
	list_del(&iclock->list);
	select_iclock();
	write_unlock_irqrestore(&iclock_lock, flags);
}
EXPORT_SYMBOL(mISDN_unregister_clock);

void
mISDN_clock_update(struct mISDNclock *iclock, int samples, struct timeval *tv)
{
	u_long		flags;
	struct timeval	tv_now;
	time_t		elapsed_sec;
	int		elapsed_8000th;

	write_lock_irqsave(&iclock_lock, flags);
	if (iclock_current != iclock) {
		printk(KERN_ERR "%s: '%s' sends us clock updates, but we do "
			"listen to '%s'. This is a bug!\n", __func__,
			iclock->name,
			iclock_current ? iclock_current->name : "nothing");
		iclock->ctl(iclock->priv, 0);
		write_unlock_irqrestore(&iclock_lock, flags);
		return;
	}
	if (iclock_tv_valid) {
		/* increment sample counter by given samples */
		iclock_count += samples;
		if (tv) { /* tv must be set, if function call is delayed */
			iclock_tv.tv_sec = tv->tv_sec;
			iclock_tv.tv_usec = tv->tv_usec;
		} else
			do_gettimeofday(&iclock_tv);
	} else {
		/* calc elapsed time by system clock */
		if (tv) { /* tv must be set, if function call is delayed */
			tv_now.tv_sec = tv->tv_sec;
			tv_now.tv_usec = tv->tv_usec;
		} else
			do_gettimeofday(&tv_now);
		elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
		elapsed_8000th = (tv_now.tv_usec / 125)
			- (iclock_tv.tv_usec / 125);
		if (elapsed_8000th < 0) {
			elapsed_sec -= 1;
			elapsed_8000th += 8000;
		}
		/* add elapsed time to counter and set new timestamp */
		iclock_count += elapsed_sec * 8000 + elapsed_8000th;
		iclock_tv.tv_sec = tv_now.tv_sec;
		iclock_tv.tv_usec = tv_now.tv_usec;
		iclock_tv_valid = 1;
		if (*debug & DEBUG_CLOCK)
			printk("Received first clock from source '%s'.\n",
			    iclock_current ? iclock_current->name : "nothing");
	}
	write_unlock_irqrestore(&iclock_lock, flags);
}
EXPORT_SYMBOL(mISDN_clock_update);

unsigned short
mISDN_clock_get(void)
{
	u_long		flags;
	struct timeval	tv_now;
	time_t		elapsed_sec;
	int		elapsed_8000th;
	u16		count;

	read_lock_irqsave(&iclock_lock, flags);
	/* calc elapsed time by system clock */
	do_gettimeofday(&tv_now);
	elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
	elapsed_8000th = (tv_now.tv_usec / 125) - (iclock_tv.tv_usec / 125);
	if (elapsed_8000th < 0) {
		elapsed_sec -= 1;
		elapsed_8000th += 8000;
	}
	/* add elapsed time to counter */
	count =	iclock_count + elapsed_sec * 8000 + elapsed_8000th;
	read_unlock_irqrestore(&iclock_lock, flags);
	return count;
}
EXPORT_SYMBOL(mISDN_clock_get);
Commit	Line	Data
3bd69ad1 AE	1	/*
	2	* Copyright 2008 by Andreas Eversberg <andreas@eversberg.eu>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*
	8	* This program is distributed in the hope that it will be useful,
	9	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	10	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	11	* GNU General Public License for more details.
	12	*
	13	* Quick API description:
	14	*
	15	* A clock source registers using mISDN_register_clock:
	16	* name = text string to name clock source
	17	* priority = value to priorize clock sources (0 = default)
	18	* ctl = callback function to enable/disable clock source
	19	* priv = private pointer of clock source
	20	* return = pointer to clock source structure;
	21	*
	22	* Note: Callback 'ctl' can be called before mISDN_register_clock returns!
	23	* Also it can be called during mISDN_unregister_clock.
	24	*
	25	* A clock source calls mISDN_clock_update with given samples elapsed, if
	26	* enabled. If function call is delayed, tv must be set with the timestamp
	27	* of the actual event.
	28	*
	29	* A clock source unregisters using mISDN_unregister_clock.
	30	*
	31	* To get current clock, call mISDN_clock_get. The signed short value
	32	* counts the number of samples since. Time since last clock event is added.
	33	*
	34	*/
	35
	36	#include <linux/types.h>
	37	#include <linux/stddef.h>
	38	#include <linux/spinlock.h>
	39	#include <linux/mISDNif.h>
	40	#include "core.h"
	41
	42	static u_int *debug;
	43	static LIST_HEAD(iclock_list);
f8532fde HE	44	static DEFINE_RWLOCK(iclock_lock);
	45	static u16 iclock_count; /* counter of last clock */
	46	static struct timeval iclock_tv; /* time stamp of last clock */
	47	static int iclock_tv_valid; /* already received one timestamp */
	48	static struct mISDNclock *iclock_current;
3bd69ad1 AE	49
	50	void
	51	mISDN_init_clock(u_int *dp)
	52	{
	53	debug = dp;
	54	do_gettimeofday(&iclock_tv);
	55	}
	56
	57	static void
	58	select_iclock(void)
	59	{
	60	struct mISDNclock iclock, bestclock = NULL, *lastclock = NULL;
	61	int pri = -128;
	62
	63	list_for_each_entry(iclock, &iclock_list, list) {
	64	if (iclock->pri > pri) {
	65	pri = iclock->pri;
	66	bestclock = iclock;
	67	}
	68	if (iclock_current == iclock)
	69	lastclock = iclock;
	70	}
	71	if (lastclock && bestclock != lastclock) {
	72	/* last used clock source still exists but changes, disable */
	73	if (*debug & DEBUG_CLOCK)
	74	printk(KERN_DEBUG "Old clock source '%s' disable.\n",
	75	lastclock->name);
	76	lastclock->ctl(lastclock->priv, 0);
	77	}
	78	if (bestclock && bestclock != iclock_current) {
	79	/* new clock source selected, enable */
	80	if (*debug & DEBUG_CLOCK)
	81	printk(KERN_DEBUG "New clock source '%s' enable.\n",
	82	bestclock->name);
	83	bestclock->ctl(bestclock->priv, 1);
	84	}
	85	if (bestclock != iclock_current) {
	86	/* no clock received yet */
	87	iclock_tv_valid = 0;
	88	}
	89	iclock_current = bestclock;
	90	}
	91
	92	struct mISDNclock
	93	mISDN_register_clock(char name, int pri, clockctl_func_t ctl, void priv)
	94	{
	95	u_long flags;
	96	struct mISDNclock *iclock;
	97
	98	if (*debug & (DEBUG_CORE \| DEBUG_CLOCK))
	99	printk(KERN_DEBUG "%s: %s %d\n", __func__, name, pri);
	100	iclock = kzalloc(sizeof(struct mISDNclock), GFP_ATOMIC);
	101	if (!iclock) {
	102	printk(KERN_ERR "%s: No memory for clock entry.\n", __func__);
	103	return NULL;
	104	}
	105	strncpy(iclock->name, name, sizeof(iclock->name)-1);
	106	iclock->pri = pri;
	107	iclock->priv = priv;
	108	iclock->ctl = ctl;
	109	write_lock_irqsave(&iclock_lock, flags);
	110	list_add_tail(&iclock->list, &iclock_list);
	111	select_iclock();
	112	write_unlock_irqrestore(&iclock_lock, flags);
113	return iclock;
114	}
115	EXPORT_SYMBOL(mISDN_register_clock);
116
117	void
118	mISDN_unregister_clock(struct mISDNclock *iclock)
119	{
120	u_long flags;
121
122	if (*debug & (DEBUG_CORE \| DEBUG_CLOCK))
123	printk(KERN_DEBUG "%s: %s %d\n", __func__, iclock->name,
124	iclock->pri);
125	write_lock_irqsave(&iclock_lock, flags);
126	if (iclock_current == iclock) {
127	if (*debug & DEBUG_CLOCK)
128	printk(KERN_DEBUG
129	"Current clock source '%s' unregisters.\n",
130	iclock->name);
131	iclock->ctl(iclock->priv, 0);
132	}
133	list_del(&iclock->list);
134	select_iclock();
135	write_unlock_irqrestore(&iclock_lock, flags);
136	}
137	EXPORT_SYMBOL(mISDN_unregister_clock);
138
139	void
140	mISDN_clock_update(struct mISDNclock iclock, int samples, struct timeval tv)
141	{
142	u_long flags;
143	struct timeval tv_now;
144	time_t elapsed_sec;
145	int elapsed_8000th;
146
147	write_lock_irqsave(&iclock_lock, flags);
148	if (iclock_current != iclock) {
149	printk(KERN_ERR "%s: '%s' sends us clock updates, but we do "
150	"listen to '%s'. This is a bug!\n", __func__,
151	iclock->name,
152	iclock_current ? iclock_current->name : "nothing");
153	iclock->ctl(iclock->priv, 0);
154	write_unlock_irqrestore(&iclock_lock, flags);
155	return;
156	}
157	if (iclock_tv_valid) {
158	/* increment sample counter by given samples */
159	iclock_count += samples;
160	if (tv) { /* tv must be set, if function call is delayed */
161	iclock_tv.tv_sec = tv->tv_sec;
162	iclock_tv.tv_usec = tv->tv_usec;
163	} else
164	do_gettimeofday(&iclock_tv);
165	} else {
166	/* calc elapsed time by system clock */
167	if (tv) { /* tv must be set, if function call is delayed */
168	tv_now.tv_sec = tv->tv_sec;
169	tv_now.tv_usec = tv->tv_usec;
170	} else
171	do_gettimeofday(&tv_now);
172	elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
173	elapsed_8000th = (tv_now.tv_usec / 125)
174	- (iclock_tv.tv_usec / 125);
175	if (elapsed_8000th < 0) {
176	elapsed_sec -= 1;
177	elapsed_8000th += 8000;
178	}
179	/* add elapsed time to counter and set new timestamp */
180	iclock_count += elapsed_sec * 8000 + elapsed_8000th;
181	iclock_tv.tv_sec = tv_now.tv_sec;
182	iclock_tv.tv_usec = tv_now.tv_usec;
183	iclock_tv_valid = 1;
184	if (*debug & DEBUG_CLOCK)
185	printk("Received first clock from source '%s'.\n",
186	iclock_current ? iclock_current->name : "nothing");
187	}
188	write_unlock_irqrestore(&iclock_lock, flags);
189	}
190	EXPORT_SYMBOL(mISDN_clock_update);
191
192	unsigned short
193	mISDN_clock_get(void)
194	{
195	u_long flags;
196	struct timeval tv_now;
197	time_t elapsed_sec;
198	int elapsed_8000th;
199	u16 count;
200
201	read_lock_irqsave(&iclock_lock, flags);
202	/* calc elapsed time by system clock */
203	do_gettimeofday(&tv_now);
204	elapsed_sec = tv_now.tv_sec - iclock_tv.tv_sec;
205	elapsed_8000th = (tv_now.tv_usec / 125) - (iclock_tv.tv_usec / 125);
206	if (elapsed_8000th < 0) {
207	elapsed_sec -= 1;
208	elapsed_8000th += 8000;
209	}
210	/* add elapsed time to counter */
211	count = iclock_count + elapsed_sec * 8000 + elapsed_8000th;
212	read_unlock_irqrestore(&iclock_lock, flags);
213	return count;
214	}
215	EXPORT_SYMBOL(mISDN_clock_get);
216