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path: root/drivers/isdn/mISDN/clock.c
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Diffstat (limited to 'drivers/isdn/mISDN/clock.c')
-rw-r--r--drivers/isdn/mISDN/clock.c216
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/isdn/mISDN/clock.c b/drivers/isdn/mISDN/clock.c
new file mode 100644
index 00000000000..44d9c3d5d33
--- /dev/null
+++ b/drivers/isdn/mISDN/clock.c
@@ -0,0 +1,216 @@
+/*
+ * 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);
+DEFINE_RWLOCK(iclock_lock);
+u16 iclock_count; /* counter of last clock */
+struct timeval iclock_tv; /* time stamp of last clock */
+int iclock_tv_valid; /* already received one timestamp */
+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);
+