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197 lines
5.6 KiB
197 lines
5.6 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Copyright 2008 by Andreas Eversberg <[email protected]> |
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* |
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* Quick API description: |
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* |
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* A clock source registers using mISDN_register_clock: |
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* name = text string to name clock source |
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* priority = value to priorize clock sources (0 = default) |
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* ctl = callback function to enable/disable clock source |
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* priv = private pointer of clock source |
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* return = pointer to clock source structure; |
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* |
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* Note: Callback 'ctl' can be called before mISDN_register_clock returns! |
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* Also it can be called during mISDN_unregister_clock. |
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* |
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* A clock source calls mISDN_clock_update with given samples elapsed, if |
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* enabled. If function call is delayed, tv must be set with the timestamp |
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* of the actual event. |
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* |
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* A clock source unregisters using mISDN_unregister_clock. |
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* |
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* To get current clock, call mISDN_clock_get. The signed short value |
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* counts the number of samples since. Time since last clock event is added. |
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*/ |
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#include <linux/slab.h> |
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#include <linux/types.h> |
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#include <linux/stddef.h> |
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#include <linux/spinlock.h> |
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#include <linux/ktime.h> |
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#include <linux/mISDNif.h> |
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#include <linux/export.h> |
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#include "core.h" |
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static u_int *debug; |
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static LIST_HEAD(iclock_list); |
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static DEFINE_RWLOCK(iclock_lock); |
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static u16 iclock_count; /* counter of last clock */ |
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static ktime_t iclock_timestamp; /* time stamp of last clock */ |
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static int iclock_timestamp_valid; /* already received one timestamp */ |
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static struct mISDNclock *iclock_current; |
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void |
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mISDN_init_clock(u_int *dp) |
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{ |
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debug = dp; |
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iclock_timestamp = ktime_get(); |
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} |
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static void |
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select_iclock(void) |
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{ |
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struct mISDNclock *iclock, *bestclock = NULL, *lastclock = NULL; |
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int pri = -128; |
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list_for_each_entry(iclock, &iclock_list, list) { |
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if (iclock->pri > pri) { |
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pri = iclock->pri; |
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bestclock = iclock; |
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} |
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if (iclock_current == iclock) |
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lastclock = iclock; |
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} |
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if (lastclock && bestclock != lastclock) { |
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/* last used clock source still exists but changes, disable */ |
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if (*debug & DEBUG_CLOCK) |
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printk(KERN_DEBUG "Old clock source '%s' disable.\n", |
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lastclock->name); |
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lastclock->ctl(lastclock->priv, 0); |
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} |
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if (bestclock && bestclock != iclock_current) { |
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/* new clock source selected, enable */ |
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if (*debug & DEBUG_CLOCK) |
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printk(KERN_DEBUG "New clock source '%s' enable.\n", |
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bestclock->name); |
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bestclock->ctl(bestclock->priv, 1); |
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} |
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if (bestclock != iclock_current) { |
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/* no clock received yet */ |
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iclock_timestamp_valid = 0; |
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} |
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iclock_current = bestclock; |
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} |
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struct mISDNclock |
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*mISDN_register_clock(char *name, int pri, clockctl_func_t *ctl, void *priv) |
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{ |
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u_long flags; |
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struct mISDNclock *iclock; |
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if (*debug & (DEBUG_CORE | DEBUG_CLOCK)) |
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printk(KERN_DEBUG "%s: %s %d\n", __func__, name, pri); |
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iclock = kzalloc(sizeof(struct mISDNclock), GFP_ATOMIC); |
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if (!iclock) { |
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printk(KERN_ERR "%s: No memory for clock entry.\n", __func__); |
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return NULL; |
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} |
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strncpy(iclock->name, name, sizeof(iclock->name) - 1); |
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iclock->pri = pri; |
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iclock->priv = priv; |
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iclock->ctl = ctl; |
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write_lock_irqsave(&iclock_lock, flags); |
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list_add_tail(&iclock->list, &iclock_list); |
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select_iclock(); |
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write_unlock_irqrestore(&iclock_lock, flags); |
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return iclock; |
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} |
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EXPORT_SYMBOL(mISDN_register_clock); |
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void |
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mISDN_unregister_clock(struct mISDNclock *iclock) |
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{ |
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u_long flags; |
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if (*debug & (DEBUG_CORE | DEBUG_CLOCK)) |
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printk(KERN_DEBUG "%s: %s %d\n", __func__, iclock->name, |
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iclock->pri); |
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write_lock_irqsave(&iclock_lock, flags); |
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if (iclock_current == iclock) { |
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if (*debug & DEBUG_CLOCK) |
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printk(KERN_DEBUG |
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"Current clock source '%s' unregisters.\n", |
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iclock->name); |
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iclock->ctl(iclock->priv, 0); |
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} |
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list_del(&iclock->list); |
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select_iclock(); |
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write_unlock_irqrestore(&iclock_lock, flags); |
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} |
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EXPORT_SYMBOL(mISDN_unregister_clock); |
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void |
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mISDN_clock_update(struct mISDNclock *iclock, int samples, ktime_t *timestamp) |
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{ |
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u_long flags; |
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ktime_t timestamp_now; |
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u16 delta; |
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write_lock_irqsave(&iclock_lock, flags); |
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if (iclock_current != iclock) { |
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printk(KERN_ERR "%s: '%s' sends us clock updates, but we do " |
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"listen to '%s'. This is a bug!\n", __func__, |
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iclock->name, |
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iclock_current ? iclock_current->name : "nothing"); |
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iclock->ctl(iclock->priv, 0); |
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write_unlock_irqrestore(&iclock_lock, flags); |
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return; |
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} |
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if (iclock_timestamp_valid) { |
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/* increment sample counter by given samples */ |
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iclock_count += samples; |
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if (timestamp) { /* timestamp must be set, if function call is delayed */ |
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iclock_timestamp = *timestamp; |
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} else { |
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iclock_timestamp = ktime_get(); |
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} |
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} else { |
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/* calc elapsed time by system clock */ |
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if (timestamp) { /* timestamp must be set, if function call is delayed */ |
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timestamp_now = *timestamp; |
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} else { |
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timestamp_now = ktime_get(); |
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} |
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delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp), |
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(NSEC_PER_SEC / 8000)); |
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/* add elapsed time to counter and set new timestamp */ |
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iclock_count += delta; |
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iclock_timestamp = timestamp_now; |
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iclock_timestamp_valid = 1; |
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if (*debug & DEBUG_CLOCK) |
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printk("Received first clock from source '%s'.\n", |
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iclock_current ? iclock_current->name : "nothing"); |
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} |
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write_unlock_irqrestore(&iclock_lock, flags); |
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} |
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EXPORT_SYMBOL(mISDN_clock_update); |
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unsigned short |
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mISDN_clock_get(void) |
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{ |
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u_long flags; |
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ktime_t timestamp_now; |
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u16 delta; |
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u16 count; |
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read_lock_irqsave(&iclock_lock, flags); |
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/* calc elapsed time by system clock */ |
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timestamp_now = ktime_get(); |
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delta = ktime_divns(ktime_sub(timestamp_now, iclock_timestamp), |
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(NSEC_PER_SEC / 8000)); |
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/* add elapsed time to counter */ |
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count = iclock_count + delta; |
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read_unlock_irqrestore(&iclock_lock, flags); |
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return count; |
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} |
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EXPORT_SYMBOL(mISDN_clock_get);
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