1 /*
2  * SPDX-License-Identifier: MIT
3  *
4  * Copyright © 2019 Intel Corporation
5  */
6 
7 #ifndef INTEL_WAKEREF_H
8 #define INTEL_WAKEREF_H
9 
10 #include <linux/atomic.h>
11 #include <linux/mutex.h>
12 #include <linux/refcount.h>
13 #include <linux/stackdepot.h>
14 #include <linux/timer.h>
15 
16 struct intel_runtime_pm;
17 
18 typedef depot_stack_handle_t intel_wakeref_t;
19 
20 struct intel_wakeref {
21 	atomic_t count;
22 	struct mutex mutex;
23 	intel_wakeref_t wakeref;
24 };
25 
26 void __intel_wakeref_init(struct intel_wakeref *wf,
27 			  struct lock_class_key *key);
28 #define intel_wakeref_init(wf) do {					\
29 	static struct lock_class_key __key;				\
30 									\
31 	__intel_wakeref_init((wf), &__key);				\
32 } while (0)
33 
34 int __intel_wakeref_get_first(struct intel_runtime_pm *rpm,
35 			      struct intel_wakeref *wf,
36 			      int (*fn)(struct intel_wakeref *wf));
37 int __intel_wakeref_put_last(struct intel_runtime_pm *rpm,
38 			     struct intel_wakeref *wf,
39 			     int (*fn)(struct intel_wakeref *wf));
40 
41 /**
42  * intel_wakeref_get: Acquire the wakeref
43  * @i915: the drm_i915_private device
44  * @wf: the wakeref
45  * @fn: callback for acquired the wakeref, called only on first acquire.
46  *
47  * Acquire a hold on the wakeref. The first user to do so, will acquire
48  * the runtime pm wakeref and then call the @fn underneath the wakeref
49  * mutex.
50  *
51  * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
52  * will be released and the acquisition unwound, and an error reported.
53  *
54  * Returns: 0 if the wakeref was acquired successfully, or a negative error
55  * code otherwise.
56  */
57 static inline int
58 intel_wakeref_get(struct intel_runtime_pm *rpm,
59 		  struct intel_wakeref *wf,
60 		  int (*fn)(struct intel_wakeref *wf))
61 {
62 	if (unlikely(!atomic_inc_not_zero(&wf->count)))
63 		return __intel_wakeref_get_first(rpm, wf, fn);
64 
65 	return 0;
66 }
67 
68 /**
69  * intel_wakeref_put: Release the wakeref
70  * @i915: the drm_i915_private device
71  * @wf: the wakeref
72  * @fn: callback for releasing the wakeref, called only on final release.
73  *
74  * Release our hold on the wakeref. When there are no more users,
75  * the runtime pm wakeref will be released after the @fn callback is called
76  * underneath the wakeref mutex.
77  *
78  * Note that @fn is allowed to fail, in which case the runtime-pm wakeref
79  * is retained and an error reported.
80  *
81  * Returns: 0 if the wakeref was released successfully, or a negative error
82  * code otherwise.
83  */
84 static inline int
85 intel_wakeref_put(struct intel_runtime_pm *rpm,
86 		  struct intel_wakeref *wf,
87 		  int (*fn)(struct intel_wakeref *wf))
88 {
89 	if (atomic_dec_and_mutex_lock(&wf->count, &wf->mutex))
90 		return __intel_wakeref_put_last(rpm, wf, fn);
91 
92 	return 0;
93 }
94 
95 /**
96  * intel_wakeref_lock: Lock the wakeref (mutex)
97  * @wf: the wakeref
98  *
99  * Locks the wakeref to prevent it being acquired or released. New users
100  * can still adjust the counter, but the wakeref itself (and callback)
101  * cannot be acquired or released.
102  */
103 static inline void
104 intel_wakeref_lock(struct intel_wakeref *wf)
105 	__acquires(wf->mutex)
106 {
107 	mutex_lock(&wf->mutex);
108 }
109 
110 /**
111  * intel_wakeref_unlock: Unlock the wakeref
112  * @wf: the wakeref
113  *
114  * Releases a previously acquired intel_wakeref_lock().
115  */
116 static inline void
117 intel_wakeref_unlock(struct intel_wakeref *wf)
118 	__releases(wf->mutex)
119 {
120 	mutex_unlock(&wf->mutex);
121 }
122 
123 /**
124  * intel_wakeref_active: Query whether the wakeref is currently held
125  * @wf: the wakeref
126  *
127  * Returns: true if the wakeref is currently held.
128  */
129 static inline bool
130 intel_wakeref_active(struct intel_wakeref *wf)
131 {
132 	return READ_ONCE(wf->wakeref);
133 }
134 
135 struct intel_wakeref_auto {
136 	struct intel_runtime_pm *rpm;
137 	struct timer_list timer;
138 	intel_wakeref_t wakeref;
139 	spinlock_t lock;
140 	refcount_t count;
141 };
142 
143 /**
144  * intel_wakeref_auto: Delay the runtime-pm autosuspend
145  * @wf: the wakeref
146  * @timeout: relative timeout in jiffies
147  *
148  * The runtime-pm core uses a suspend delay after the last wakeref
149  * is released before triggering runtime suspend of the device. That
150  * delay is configurable via sysfs with little regard to the device
151  * characteristics. Instead, we want to tune the autosuspend based on our
152  * HW knowledge. intel_wakeref_auto() delays the sleep by the supplied
153  * timeout.
154  *
155  * Pass @timeout = 0 to cancel a previous autosuspend by executing the
156  * suspend immediately.
157  */
158 void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout);
159 
160 void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
161 			     struct intel_runtime_pm *rpm);
162 void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf);
163 
164 #endif /* INTEL_WAKEREF_H */
165