1 /*
2 * Copyright (c) 2017 Apple Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 #include <kern/misc_protos.h>
29 #include <x86_64/machine_remote_time.h>
30 #include <machine/atomic.h>
31 #include <kern/locks.h>
32 #include <kern/clock.h>
33 #include <kern/remote_time.h>
34
35 void mach_bridge_send_timestamp(uint64_t timestamp);
36
37 extern _Atomic uint32_t bt_init_flag;
38 extern uint32_t bt_enable_flag;
39
40 /*
41 * Delay sending timestamps by certain interval to
42 * avoid overwriting sentinel values
43 */
44 #define DELAY_INTERVAL_NS (50 * NSEC_PER_MSEC)
45 static uint64_t bt_delay_timestamp = 0;
46 static mach_bridge_regwrite_timestamp_func_t bridge_regwrite_timestamp_callback = NULL;
47
48 /*
49 * This function should only be called by the kext
50 * responsible for sending timestamps across the link
51 */
52 void
mach_bridge_register_regwrite_timestamp_callback(mach_bridge_regwrite_timestamp_func_t func)53 mach_bridge_register_regwrite_timestamp_callback(mach_bridge_regwrite_timestamp_func_t func)
54 {
55 static uint64_t delay_amount = 0;
56
57 if (!os_atomic_load(&bt_init_flag, relaxed)) {
58 nanoseconds_to_absolutetime(DELAY_INTERVAL_NS, &delay_amount);
59 os_atomic_store(&bt_init_flag, 1, release);
60 }
61
62 lck_spin_lock(&bt_maintenance_lock);
63 bridge_regwrite_timestamp_callback = func;
64 bt_enable_flag = (func != NULL) ? 1 : 0;
65 bt_delay_timestamp = mach_absolute_time() + delay_amount;
66 lck_spin_unlock(&bt_maintenance_lock);
67 }
68
69 void
mach_bridge_send_timestamp(uint64_t timestamp)70 mach_bridge_send_timestamp(uint64_t timestamp)
71 {
72 LCK_SPIN_ASSERT(&bt_maintenance_lock, LCK_ASSERT_OWNED);
73
74 if (bt_delay_timestamp > 0) {
75 uint64_t now = mach_absolute_time();
76 if (now < bt_delay_timestamp) {
77 return;
78 }
79 bt_delay_timestamp = 0;
80 }
81
82 if (bridge_regwrite_timestamp_callback) {
83 bridge_regwrite_timestamp_callback(timestamp);
84 }
85 }
86