1 /*
2  * Copyright 2012 Red Hat Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * Authors: Ben Skeggs
23  */
24 #include "priv.h"
25 
26 s64
27 nvkm_timer_wait_test(struct nvkm_timer_wait *wait)
28 {
29 	struct nvkm_subdev *subdev = &wait->tmr->subdev;
30 	u64 time = nvkm_timer_read(wait->tmr);
31 
32 	if (wait->reads == 0) {
33 		wait->time0 = time;
34 		wait->time1 = time;
35 	}
36 
37 	if (wait->time1 == time) {
38 		if (wait->reads++ == 16) {
39 			nvkm_fatal(subdev, "stalled at %016llx\n", time);
40 			return -ETIMEDOUT;
41 		}
42 	} else {
43 		wait->time1 = time;
44 		wait->reads = 1;
45 	}
46 
47 	if (wait->time1 - wait->time0 > wait->limit)
48 		return -ETIMEDOUT;
49 
50 	return wait->time1 - wait->time0;
51 }
52 
53 void
54 nvkm_timer_wait_init(struct nvkm_device *device, u64 nsec,
55 		     struct nvkm_timer_wait *wait)
56 {
57 	wait->tmr = device->timer;
58 	wait->limit = nsec;
59 	wait->reads = 0;
60 }
61 
62 u64
63 nvkm_timer_read(struct nvkm_timer *tmr)
64 {
65 	return tmr->func->read(tmr);
66 }
67 
68 void
69 nvkm_timer_alarm_trigger(struct nvkm_timer *tmr)
70 {
71 	struct nvkm_alarm *alarm, *atemp;
72 	unsigned long flags;
73 	LIST_HEAD(exec);
74 
75 	/* Process pending alarms. */
76 	spin_lock_irqsave(&tmr->lock, flags);
77 	list_for_each_entry_safe(alarm, atemp, &tmr->alarms, head) {
78 		/* Have we hit the earliest alarm that hasn't gone off? */
79 		if (alarm->timestamp > nvkm_timer_read(tmr)) {
80 			/* Schedule it.  If we didn't race, we're done. */
81 			tmr->func->alarm_init(tmr, alarm->timestamp);
82 			if (alarm->timestamp > nvkm_timer_read(tmr))
83 				break;
84 		}
85 
86 		/* Move to completed list.  We'll drop the lock before
87 		 * executing the callback so it can reschedule itself.
88 		 */
89 		list_del_init(&alarm->head);
90 		list_add(&alarm->exec, &exec);
91 	}
92 
93 	/* Shut down interrupt if no more pending alarms. */
94 	if (list_empty(&tmr->alarms))
95 		tmr->func->alarm_fini(tmr);
96 	spin_unlock_irqrestore(&tmr->lock, flags);
97 
98 	/* Execute completed callbacks. */
99 	list_for_each_entry_safe(alarm, atemp, &exec, exec) {
100 		list_del(&alarm->exec);
101 		alarm->func(alarm);
102 	}
103 }
104 
105 void
106 nvkm_timer_alarm(struct nvkm_timer *tmr, u32 nsec, struct nvkm_alarm *alarm)
107 {
108 	struct nvkm_alarm *list;
109 	unsigned long flags;
110 
111 	/* Remove alarm from pending list.
112 	 *
113 	 * This both protects against the corruption of the list,
114 	 * and implements alarm rescheduling/cancellation.
115 	 */
116 	spin_lock_irqsave(&tmr->lock, flags);
117 	list_del_init(&alarm->head);
118 
119 	if (nsec) {
120 		/* Insert into pending list, ordered earliest to latest. */
121 		alarm->timestamp = nvkm_timer_read(tmr) + nsec;
122 		list_for_each_entry(list, &tmr->alarms, head) {
123 			if (list->timestamp > alarm->timestamp)
124 				break;
125 		}
126 
127 		list_add_tail(&alarm->head, &list->head);
128 
129 		/* Update HW if this is now the earliest alarm. */
130 		list = list_first_entry(&tmr->alarms, typeof(*list), head);
131 		if (list == alarm) {
132 			tmr->func->alarm_init(tmr, alarm->timestamp);
133 			/* This shouldn't happen if callers aren't stupid.
134 			 *
135 			 * Worst case scenario is that it'll take roughly
136 			 * 4 seconds for the next alarm to trigger.
137 			 */
138 			WARN_ON(alarm->timestamp <= nvkm_timer_read(tmr));
139 		}
140 	}
141 	spin_unlock_irqrestore(&tmr->lock, flags);
142 }
143 
144 static void
145 nvkm_timer_intr(struct nvkm_subdev *subdev)
146 {
147 	struct nvkm_timer *tmr = nvkm_timer(subdev);
148 	tmr->func->intr(tmr);
149 }
150 
151 static int
152 nvkm_timer_fini(struct nvkm_subdev *subdev, bool suspend)
153 {
154 	struct nvkm_timer *tmr = nvkm_timer(subdev);
155 	tmr->func->alarm_fini(tmr);
156 	return 0;
157 }
158 
159 static int
160 nvkm_timer_init(struct nvkm_subdev *subdev)
161 {
162 	struct nvkm_timer *tmr = nvkm_timer(subdev);
163 	if (tmr->func->init)
164 		tmr->func->init(tmr);
165 	tmr->func->time(tmr, ktime_to_ns(ktime_get()));
166 	nvkm_timer_alarm_trigger(tmr);
167 	return 0;
168 }
169 
170 static void *
171 nvkm_timer_dtor(struct nvkm_subdev *subdev)
172 {
173 	return nvkm_timer(subdev);
174 }
175 
176 static const struct nvkm_subdev_func
177 nvkm_timer = {
178 	.dtor = nvkm_timer_dtor,
179 	.init = nvkm_timer_init,
180 	.fini = nvkm_timer_fini,
181 	.intr = nvkm_timer_intr,
182 };
183 
184 int
185 nvkm_timer_new_(const struct nvkm_timer_func *func, struct nvkm_device *device,
186 		int index, struct nvkm_timer **ptmr)
187 {
188 	struct nvkm_timer *tmr;
189 
190 	if (!(tmr = *ptmr = kzalloc(sizeof(*tmr), GFP_KERNEL)))
191 		return -ENOMEM;
192 
193 	nvkm_subdev_ctor(&nvkm_timer, device, index, &tmr->subdev);
194 	tmr->func = func;
195 	INIT_LIST_HEAD(&tmr->alarms);
196 	spin_lock_init(&tmr->lock);
197 	return 0;
198 }
199