Merge changes from timing branch

- Convert chan_iax2 to use the timing API
 - Convert usage of timing in the core to use the timing API instead of
   using DAHDI directly
 - Make a change to the timing API to add the set_rate() function
 - change the timing core to use a rwlock
 - merge a timing implementation, res_timing_dahdi

Basic testing was successful using res_timing_dahdi


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@122523 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_iax2.c

@@ -31,7 +31,6 @@
  */
 
 /*** MODULEINFO
-	<use>dahdi</use>
 	<use>crypto</use>
  ***/
 
@@ -55,7 +54,6 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include <sys/stat.h>
 #include <regex.h>
 
-#include "asterisk/dahdi.h"
 #include "asterisk/paths.h"	/* need ast_config_AST_DATA_DIR for firmware */
 
 #include "asterisk/lock.h"
@@ -89,6 +87,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/linkedlists.h"
 #include "asterisk/event.h"
 #include "asterisk/astobj2.h"
+#include "asterisk/timing.h"
 
 #include "iax2.h"
 #include "iax2-parser.h"
@@ -7253,32 +7252,17 @@ static inline int iax2_trunk_expired(struct iax2_trunk_peer *tpeer, struct timev
 
 static int timing_read(int *id, int fd, short events, void *cbdata)
 {
-	char buf[1024];
 	int res, processed = 0, totalcalls = 0;
 	struct iax2_trunk_peer *tpeer = NULL, *drop = NULL;
-#ifdef DAHDI_TIMERACK
-	int x = 1;
-#endif
 	struct timeval now = ast_tvnow();
+
 	if (iaxtrunkdebug)
 		ast_verbose("Beginning trunk processing. Trunk queue ceiling is %d bytes per host\n", trunkmaxsize);
-	if (events & AST_IO_PRI) {
-#ifdef DAHDI_TIMERACK
-		/* Great, this is a timing interface, just call the ioctl */
-		if (ioctl(fd, DAHDI_TIMERACK, &x)) {
-			ast_log(LOG_WARNING, "Unable to acknowledge DAHDI timer. IAX trunking will fail!\n");
-			usleep(1);
-			return -1;
-		}
-#endif		
-	} else {
-		/* Read and ignore from the pseudo channel for timing */
-		res = read(fd, buf, sizeof(buf));
-		if (res < 1) {
-			ast_log(LOG_WARNING, "Unable to read from timing fd\n");
-			return 1;
-		}
+
+	if (timingfd > -1) { 
+		ast_timer_ack(timingfd, 1);
 	}
+
 	/* For each peer that supports trunking... */
 	AST_LIST_LOCK(&tpeers);
 	AST_LIST_TRAVERSE_SAFE_BEGIN(&tpeers, tpeer, list) {
@@ -10844,21 +10828,6 @@ static void prune_peers(void)
 	}
 }
 
-static void set_timing(void)
-{
-#ifdef HAVE_DAHDI
-	int bs = trunkfreq * 8;
-	if (timingfd > -1) {
-		if (
-#ifdef DAHDI_TIMERACK
-			ioctl(timingfd, DAHDI_TIMERCONFIG, &bs) &&
-#endif			
-			ioctl(timingfd, DAHDI_SET_BLOCKSIZE, &bs))
-			ast_log(LOG_WARNING, "Unable to set blocksize on timing source\n");
-	}
-#endif
-}
-
 static void set_config_destroy(void)
 {
 	strcpy(accountcode, "");
@@ -11265,7 +11234,6 @@ static int set_config(char *config_file, int reload)
 		cat = ast_category_browse(cfg, cat);
 	}
 	ast_config_destroy(cfg);
-	set_timing();
 	return 1;
 }
 
@@ -12050,6 +12018,10 @@ static int __unload_module(void)
 	ao2_ref(users, -1);
 	ao2_ref(iax_peercallno_pvts, -1);
 
+	if (timingfd > -1) {
+		ast_timer_close(timingfd);
+	}
+
 	con = ast_context_find(regcontext);
 	if (con)
 		ast_context_destroy(con, "IAX2");
@@ -12121,16 +12093,6 @@ static int load_module(void)
 	iax_set_error(iax_error_output);
 	jb_setoutput(jb_error_output, jb_warning_output, NULL);
 
-#ifdef HAVE_DAHDI
-#ifdef DAHDI_TIMERACK
-	timingfd = open("/dev/dahdi/timer", O_RDWR);
-	if (timingfd < 0)
-#endif
-		timingfd = open("/dev/dahdi/pseudo", O_RDWR);
-	if (timingfd < 0) 
-		ast_log(LOG_WARNING, "Unable to open IAX timing interface: %s\n", strerror(errno));
-#endif		
-
 	memset(iaxs, 0, sizeof(iaxs));
 
 	for (x = 0; x < ARRAY_LEN(iaxsl); x++) {
@@ -12178,6 +12140,11 @@ static int load_module(void)
 	if(set_config(config, 0) == -1)
 		return AST_MODULE_LOAD_DECLINE;
 
+	timingfd = ast_timer_open();
+	if (timingfd > -1) {
+		ast_timer_set_rate(timingfd, trunkfreq);
+	}
+
  	if (ast_channel_register(&iax2_tech)) {
 		ast_log(LOG_ERROR, "Unable to register channel class %s\n", "IAX2");
 		__unload_module();

include/asterisk/channel.h

@@ -1423,9 +1423,17 @@ int ast_autoservice_start(struct ast_channel *chan);
  */
 int ast_autoservice_stop(struct ast_channel *chan);
 
-/* If built with dahdi optimizations, force a scheduled expiration on the
-   timer fd, at which point we call the callback function / data */
-int ast_settimeout(struct ast_channel *c, int samples, int (*func)(const void *data), void *data);
+/*!
+ * \brief Enable or disable timer ticks for a channel
+ *
+ * \arg rate number of timer ticks per second
+ *
+ * If timers are supported, force a scheduled expiration on the
+ * timer fd, at which point we call the callback function / data 
+ *
+ * Call this function with a rate of 0 to turn off the timer ticks
+ */
+int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data);
 
 /*!	\brief Transfer a channel (if supported).  Returns -1 on error, 0 if not supported
    and 1 if supported and requested 

include/asterisk/timing.h

@@ -65,8 +65,9 @@ enum ast_timing_event {
  * public API calls.
  */
 struct ast_timing_functions {
-	int (*timer_open)(unsigned int rate);
+	int (*timer_open)(void);
 	void (*timer_close)(int handle);
+	int (*timer_set_rate)(int handle, unsigned int rate);
 	void (*timer_ack)(int handle, unsigned int quantity);
 	int (*timer_enable_continuous)(int handle);
 	int (*timer_disable_continuous)(int handle);
@@ -97,12 +98,10 @@ void ast_uninstall_timing_functions(void *handle);
 /*!
  * \brief Open a timing fd
  *
- * \arg rate number of timer ticks per second
- *
  * \retval -1 error, with errno set
  * \retval >=0 success
  */
-int ast_timer_open(unsigned int rate);
+int ast_timer_open(void);
 
 /*!
  * \brief Close an opened timing handle
@@ -113,6 +112,21 @@ int ast_timer_open(unsigned int rate);
  */
 void ast_timer_close(int handle);
 
+/*!
+ * \brief Set the timing tick rate
+ *
+ * \arg handle timing fd returned from timer_open()
+ * \arg rate ticks per second, 0 turns the ticks off if needed
+ *
+ * Use this function if you want the timing fd to show input at a certain
+ * rate.  The other alternative use of a timing fd, is using the continuous
+ * mode.
+ *
+ * \retval -1 error, with errno set
+ * \retval 0 success
+ */
+int ast_timer_set_rate(int handle, unsigned int rate);
+
 /*!
  * \brief Acknowledge a timer event
  *

main/asterisk.c

@@ -3299,35 +3299,7 @@ int main(int argc, char *argv[])
 		printf("%s", term_quit());
 		exit(1);
 	}
-#ifdef HAVE_DAHDI
-	{
-		int fd;
-		int x = 160;
-		fd = open("/dev/dahdi/timer", O_RDWR);
-		if (fd >= 0) {
-			if (ioctl(fd, DAHDI_TIMERCONFIG, &x)) {
-				ast_log(LOG_ERROR, "You have DAHDI built and drivers loaded, but the DAHDI timer test failed to set DAHDI_TIMERCONFIG to %d.\n", x);
-				exit(1);
-			}
-			if ((x = ast_wait_for_input(fd, 300)) < 0) {
-				ast_log(LOG_ERROR, "You have DAHDI built and drivers loaded, but the DAHDI timer could not be polled during the DAHDI timer test.\n");
-				exit(1);
-			}
-			if (!x) {
-				const char dahdi_timer_error[] = {
-					"Asterisk has detected a problem with your DAHDI configuration and will shutdown for your protection.  You have options:"
-					"\n\t1. You only have to compile DAHDI support into Asterisk if you need it.  One option is to recompile without DAHDI support."
-					"\n\t2. You only have to load DAHDI drivers if you want to take advantage of DAHDI services.  One option is to unload DAHDI modules if you don't need them."
-					"\n\t3. If you need DAHDI services, you must correctly configure DAHDI."
-				};
-				ast_log(LOG_ERROR, "%s\n", dahdi_timer_error);
-				usleep(100);
-				exit(1);
-			}
-			close(fd);
-		}
-	}
-#endif
+
 	threadstorage_init();
 
 	astobj2_init();

main/channel.c

@@ -61,6 +61,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/threadstorage.h"
 #include "asterisk/slinfactory.h"
 #include "asterisk/audiohook.h"
+#include "asterisk/timing.h"
 
 #ifdef HAVE_EPOLL
 #include <sys/epoll.h>
@@ -808,27 +809,19 @@ struct ast_channel *ast_channel_alloc(int needqueue, int state, const char *cid_
 #endif
 	}
 
-#ifdef HAVE_DAHDI
-	tmp->timingfd = open("/dev/dahdi/timer", O_RDWR);
+	tmp->timingfd = ast_timer_open();
 	if (tmp->timingfd > -1) {
-		/* Check if timing interface supports new
-		   ping/pong scheme */
-		flags = 1;
-		if (!ioctl(tmp->timingfd, DAHDI_TIMERPONG, &flags))
 		needqueue = 0;
 	}
-#else
-	tmp->timingfd = -1;					
-#endif					
 
 	if (needqueue) {
 		if (pipe(tmp->alertpipe)) {
 			ast_log(LOG_WARNING, "Channel allocation failed: Can't create alert pipe!\n");
 alertpipe_failed:
-#ifdef HAVE_DAHDI
-			if (tmp->timingfd > -1)
-				close(tmp->timingfd);
-#endif
+			if (tmp->timingfd > -1) {
+				ast_timer_close(tmp->timingfd);
+			}
+
 			sched_context_destroy(tmp->sched);
 			ast_string_field_free_memory(tmp);
 			ast_free(tmp);
@@ -1007,10 +1000,8 @@ int ast_queue_frame(struct ast_channel *chan, struct ast_frame *fin)
 		if (write(chan->alertpipe[1], &blah, sizeof(blah)) != sizeof(blah))
 			ast_log(LOG_WARNING, "Unable to write to alert pipe on %s, frametype/subclass %d/%d (qlen = %d): %s!\n",
 				chan->name, f->frametype, f->subclass, qlen, strerror(errno));
-#ifdef HAVE_DAHDI
 	} else if (chan->timingfd > -1) {
-		ioctl(chan->timingfd, DAHDI_TIMERPING, &blah);
-#endif				
+		ast_timer_enable_continuous(chan->timingfd);
 	} else if (ast_test_flag(chan, AST_FLAG_BLOCKING)) {
 		pthread_kill(chan->blocker, SIGURG);
 	}
@@ -1343,7 +1334,7 @@ void ast_channel_free(struct ast_channel *chan)
 	if ((fd = chan->alertpipe[1]) > -1)
 		close(fd);
 	if ((fd = chan->timingfd) > -1)
-		close(fd);
+		ast_timer_close(fd);
 #ifdef HAVE_EPOLL
 	for (i = 0; i < AST_MAX_FDS; i++) {
 		if (chan->epfd_data[i])
@@ -1795,7 +1786,7 @@ int ast_activate_generator(struct ast_channel *chan, struct ast_generator *gen,
 	}
 	
 	if (!res) {
-		ast_settimeout(chan, 160, generator_force, chan);
+		ast_settimeout(chan, 50, generator_force, chan);
 		chan->generator = gen;
 	}
 
@@ -2181,21 +2172,26 @@ int ast_waitfordigit(struct ast_channel *c, int ms)
 	return ast_waitfordigit_full(c, ms, -1, -1);
 }
 
-int ast_settimeout(struct ast_channel *c, int samples, int (*func)(const void *data), void *data)
+int ast_settimeout(struct ast_channel *c, unsigned int rate, int (*func)(const void *data), void *data)
 {
-	int res = -1;
-#ifdef HAVE_DAHDI
-	if (c->timingfd > -1) {
-		if (!func) {
-			samples = 0;
-			data = 0;
+	int res;
+
+	if (c->timingfd == -1) {
+		return -1;
 	}
-		ast_debug(1, "Scheduling timer at %d sample intervals\n", samples);
-		res = ioctl(c->timingfd, DAHDI_TIMERCONFIG, &samples);
+
+	if (!func) {
+		rate = 0;
+		data = NULL;
+	}
+
+	ast_debug(1, "Scheduling timer at %u timer ticks per second\n", rate);
+
+	res = ast_timer_set_rate(c->timingfd, rate);
+
 	c->timingfunc = func;
 	c->timingdata = data;
-	}
-#endif	
+
 	return res;
 }
 
@@ -2334,7 +2330,7 @@ static void ast_read_generator_actions(struct ast_channel *chan, struct ast_fram
 	} else if (f->frametype == AST_FRAME_CNG) {
 		if (chan->generator && !chan->timingfunc && (chan->timingfd > -1)) {
 			ast_debug(1, "Generator got CNG, switching to timed mode\n");
-			ast_settimeout(chan, 160, generator_force, chan);
+			ast_settimeout(chan, 50, generator_force, chan);
 		}
 	}
 }

main/file.c

@@ -29,6 +29,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 
 #include <dirent.h>
 #include <sys/stat.h>
+#include <math.h>
 
 #include "asterisk/_private.h"	/* declare ast_file_init() */
 #include "asterisk/paths.h"	/* use ast_config_AST_DATA_DIR */
@@ -659,21 +660,17 @@ static enum fsread_res ast_readaudio_callback(struct ast_filestream *s)
 		}
 	}
 	if (whennext != s->lasttimeout) {
-#ifdef HAVE_DAHDI
 		if (s->owner->timingfd > -1) {
-			int zap_timer_samples = whennext;
-			int rate;
-			/* whennext is in samples, but DAHDI timers operate in 8 kHz samples. */
-			if ((rate = ast_format_rate(s->fmt->format)) != 8000) {
-				float factor;
-				factor = ((float) rate) / ((float) 8000.0); 
-				zap_timer_samples = (int) ( ((float) zap_timer_samples) / factor );
-			}
-			ast_settimeout(s->owner, zap_timer_samples, ast_fsread_audio, s);
-		} else
-#endif		
+			float samp_rate = (float) ast_format_rate(s->fmt->format);
+			unsigned int rate;
+
+			rate = (unsigned int) roundf(samp_rate / ((float) whennext));
+
+			ast_settimeout(s->owner, rate, ast_fsread_audio, s);
+		} else {
 			s->owner->streamid = ast_sched_add(s->owner->sched, 
 				whennext / (ast_format_rate(s->fmt->format) / 1000), ast_fsread_audio, s);
+		}
 		s->lasttimeout = whennext;
 		return FSREAD_SUCCESS_NOSCHED;
 	}
@@ -681,9 +678,7 @@ static enum fsread_res ast_readaudio_callback(struct ast_filestream *s)
 
 return_failure:
 	s->owner->streamid = -1;
-#ifdef HAVE_DAHDI
 	ast_settimeout(s->owner, 0, NULL, NULL);
-#endif			
 	return FSREAD_FAILURE;
 }
 
@@ -792,9 +787,7 @@ int ast_closestream(struct ast_filestream *f)
 		if (f->fmt->format & AST_FORMAT_AUDIO_MASK) {
 			f->owner->stream = NULL;
 			AST_SCHED_DEL(f->owner->sched, f->owner->streamid);
-#ifdef HAVE_DAHDI
 			ast_settimeout(f->owner, 0, NULL, NULL);
-#endif			
 		} else {
 			f->owner->vstream = NULL;
 			AST_SCHED_DEL(f->owner->sched, f->owner->vstreamid);

main/timing.c

@@ -30,7 +30,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/timing.h"
 #include "asterisk/lock.h"
 
-AST_MUTEX_DEFINE_STATIC(lock);
+AST_RWLOCK_DEFINE_STATIC(lock);
 
 static struct ast_timing_functions timer_funcs;
 
@@ -38,6 +38,7 @@ void *ast_install_timing_functions(struct ast_timing_functions *funcs)
 {
 	if (!funcs->timer_open ||
 	    !funcs->timer_close ||
+		!funcs->timer_set_rate ||
 	    !funcs->timer_ack ||
 	    !funcs->timer_get_event ||
 	    !funcs->timer_enable_continuous ||
@@ -45,94 +46,113 @@ void *ast_install_timing_functions(struct ast_timing_functions *funcs)
 		return NULL;
 	}
 
-	ast_mutex_lock(&lock);
+	ast_rwlock_wrlock(&lock);
 
 	if (timer_funcs.timer_open) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
+		ast_log(LOG_NOTICE, "Multiple timing modules are loaded.  You should only load one.\n");
 		return NULL;
 	}
 	
 	timer_funcs = *funcs;
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 
 	return &timer_funcs;
 }
 
 void ast_uninstall_timing_functions(void *handle)
 {
-	ast_mutex_lock(&lock);
+	ast_rwlock_wrlock(&lock);
 
 	if (handle != &timer_funcs) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return;
 	}
 
 	memset(&timer_funcs, 0, sizeof(timer_funcs));
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 }
 
-int ast_timer_open(unsigned int rate)
+int ast_timer_open(void)
 {
 	int timer;
 
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_open) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return -1;
 	}
 
-	timer = timer_funcs.timer_open(rate);
+	timer = timer_funcs.timer_open();
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 
 	return timer;
 }
 
 void ast_timer_close(int timer)
 {
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_close) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return;
 	}
 
 	timer_funcs.timer_close(timer);
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
+}
+
+int ast_timer_set_rate(int handle, unsigned int rate)
+{
+	int res;
+
+	ast_rwlock_rdlock(&lock);
+
+	if (!timer_funcs.timer_set_rate) {
+		ast_rwlock_unlock(&lock);
+		return -1;
+	}
+
+	res = timer_funcs.timer_set_rate(handle, rate);
+
+	ast_rwlock_unlock(&lock);
+
+	return res;
 }
 
 void ast_timer_ack(int handle, unsigned int quantity)
 {
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_ack) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return;
 	}
 
 	timer_funcs.timer_ack(handle, quantity);
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 }
 
 int ast_timer_enable_continuous(int handle)
 {
 	int result;
 
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_enable_continuous) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return -1;
 	}
 
 	result = timer_funcs.timer_enable_continuous(handle);
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 
 	return result;
 }
@@ -141,16 +161,16 @@ int ast_timer_disable_continous(int handle)
 {
 	int result;
 
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_disable_continuous) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return -1;
 	}
 
 	result = timer_funcs.timer_disable_continuous(handle);
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 
 	return result;
 }
@@ -159,16 +179,16 @@ enum ast_timing_event ast_timer_get_event(int handle)
 {
 	enum ast_timing_event result;
 
-	ast_mutex_lock(&lock);
+	ast_rwlock_rdlock(&lock);
 
 	if (!timer_funcs.timer_get_event) {
-		ast_mutex_unlock(&lock);
+		ast_rwlock_unlock(&lock);
 		return -1;
 	}
 
 	result = timer_funcs.timer_get_event(handle);
 
-	ast_mutex_unlock(&lock);
+	ast_rwlock_unlock(&lock);
 
 	return result;
 }

res/res_timing_dahdi.c

@@ -0,0 +1,188 @@
+/*
+ * Asterisk -- An open source telephony toolkit.
+ *
+ * Copyright (C) 2008, Digium, Inc.
+ *
+ * Russell Bryant <russell@digium.com>
+ *
+ * See http://www.asterisk.org for more information about
+ * the Asterisk project. Please do not directly contact
+ * any of the maintainers of this project for assistance;
+ * the project provides a web site, mailing lists and IRC
+ * channels for your use.
+ *
+ * This program is free software, distributed under the terms of
+ * the GNU General Public License Version 2. See the LICENSE file
+ * at the top of the source tree.
+ */
+
+/*! 
+ * \file
+ * \author Russell Bryant <russell@digium.com>
+ *
+ * \brief DAHDI timing interface 
+ */
+
+/*** MODULEINFO
+	<depend>dahdi</depend>
+ ***/
+
+#include "asterisk.h"
+
+ASTERISK_FILE_VERSION(__FILE__, "$Revision$");
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <math.h>
+
+#include "asterisk/module.h"
+#include "asterisk/timing.h"
+#include "asterisk/dahdi.h"
+#include "asterisk/utils.h"
+
+static void *timing_funcs_handle;
+
+static int dahdi_timer_open(void);
+static void dahdi_timer_close(int handle);
+static int dahdi_timer_set_rate(int handle, unsigned int rate);
+static void dahdi_timer_ack(int handle, unsigned int quantity);
+static int dahdi_timer_enable_continuous(int handle);
+static int dahdi_timer_disable_continuous(int handle);
+static enum ast_timing_event dahdi_timer_get_event(int handle);
+
+static struct ast_timing_functions dahdi_timing_functions = {
+	.timer_open = dahdi_timer_open,
+	.timer_close = dahdi_timer_close,
+	.timer_set_rate = dahdi_timer_set_rate,
+	.timer_ack = dahdi_timer_ack,
+	.timer_enable_continuous = dahdi_timer_enable_continuous,
+	.timer_disable_continuous = dahdi_timer_disable_continuous,
+	.timer_get_event = dahdi_timer_get_event,
+};
+
+static int dahdi_timer_open(void)
+{
+	return open("/dev/dahdi/timer", O_RDWR);
+}
+
+static void dahdi_timer_close(int handle)
+{
+	close(handle);
+}
+
+static int dahdi_timer_set_rate(int handle, unsigned int rate)
+{
+	int samples;
+
+	/* DAHDI timers are configured using a number of samples,
+	 * based on an 8 kHz sample rate. */
+	samples = (unsigned int) roundf((8000.0 / ((float) rate)));
+
+	if (ioctl(handle, DAHDI_TIMERCONFIG, &samples)) {
+		ast_log(LOG_ERROR, "Failed to configure DAHDI timing fd for %u sample timer ticks\n",
+			samples);
+		return -1;
+	}
+
+	return 0;
+}
+
+static void dahdi_timer_ack(int handle, unsigned int quantity)
+{
+	ioctl(handle, DAHDI_TIMERACK, &quantity);
+}
+
+static int dahdi_timer_enable_continuous(int handle)
+{
+	int flags = 1;
+
+	return ioctl(handle, DAHDI_TIMERPING, &flags) ? -1 : 0;
+}
+
+static int dahdi_timer_disable_continuous(int handle)
+{
+	int flags = -1;
+
+	return ioctl(handle, DAHDI_TIMERPONG, &flags) ? -1 : 0;
+}
+
+static enum ast_timing_event dahdi_timer_get_event(int handle)
+{
+	int res;
+	int event;
+
+	res = ioctl(handle, DAHDI_GETEVENT, &event);
+
+	if (res) {
+		event = DAHDI_EVENT_TIMER_EXPIRED;
+	}
+
+	switch (event) {
+	case DAHDI_EVENT_TIMER_PING:
+		return AST_TIMING_EVENT_CONTINUOUS;
+	case DAHDI_EVENT_TIMER_EXPIRED:
+	default:
+		return AST_TIMING_EVENT_EXPIRED;	
+	}
+}
+
+static int dahdi_test_timer(void)
+{
+	int fd;
+	int x = 160;
+	
+	fd = open("/dev/dahdi/timer", O_RDWR);
+
+	if (fd < 0) {
+		return -1;
+	}
+
+	if (ioctl(fd, DAHDI_TIMERCONFIG, &x)) {
+		ast_log(LOG_ERROR, "You have DAHDI built and drivers loaded, but the DAHDI timer test failed to set DAHDI_TIMERCONFIG to %d.\n", x);
+		close(fd);
+		return -1;
+	}
+
+	if ((x = ast_wait_for_input(fd, 300)) < 0) {
+		ast_log(LOG_ERROR, "You have DAHDI built and drivers loaded, but the DAHDI timer could not be polled during the DAHDI timer test.\n");
+		close(fd);
+		return -1;
+	}
+
+	if (!x) {
+		const char dahdi_timer_error[] = {
+			"Asterisk has detected a problem with your DAHDI configuration and will shutdown for your protection.  You have options:"
+			"\n\t1. You only have to compile DAHDI support into Asterisk if you need it.  One option is to recompile without DAHDI support."
+			"\n\t2. You only have to load DAHDI drivers if you want to take advantage of DAHDI services.  One option is to unload DAHDI modules if you don't need them."
+			"\n\t3. If you need DAHDI services, you must correctly configure DAHDI."
+		};
+		ast_log(LOG_ERROR, "%s\n", dahdi_timer_error);
+		usleep(100);
+		close(fd);
+		return -1;
+	}
+
+	close(fd);
+
+	return 0;
+}
+
+static int load_module(void)
+{
+	if (dahdi_test_timer()) {
+		return AST_MODULE_LOAD_DECLINE;
+	}
+
+	return (timing_funcs_handle = ast_install_timing_functions(&dahdi_timing_functions)) ?
+		AST_MODULE_LOAD_SUCCESS : AST_MODULE_LOAD_DECLINE;
+}
+
+static int unload_module(void)
+{
+	ast_uninstall_timing_functions(timing_funcs_handle);
+
+	return 0;
+}
+
+AST_MODULE_INFO_STANDARD(ASTERISK_GPL_KEY, "DAHDI Timing Interface");