1 /* SPDX-License-Identifier: MIT */
2 /*
3  * Copyright © 2019 Intel Corporation
4  */
5 
6 #ifndef __INTEL_RUNTIME_PM_H__
7 #define __INTEL_RUNTIME_PM_H__
8 
9 #include <linux/types.h>
10 
11 #include "intel_wakeref.h"
12 
13 #include "i915_utils.h"
14 
15 struct device;
16 struct drm_i915_private;
17 struct drm_printer;
18 
19 /*
20  * This struct helps tracking the state needed for runtime PM, which puts the
21  * device in PCI D3 state. Notice that when this happens, nothing on the
22  * graphics device works, even register access, so we don't get interrupts nor
23  * anything else.
24  *
25  * Every piece of our code that needs to actually touch the hardware needs to
26  * either call intel_runtime_pm_get or call intel_display_power_get with the
27  * appropriate power domain.
28  *
29  * Our driver uses the autosuspend delay feature, which means we'll only really
30  * suspend if we stay with zero refcount for a certain amount of time. The
31  * default value is currently very conservative (see intel_runtime_pm_enable), but
32  * it can be changed with the standard runtime PM files from sysfs.
33  *
34  * The irqs_disabled variable becomes true exactly after we disable the IRQs and
35  * goes back to false exactly before we reenable the IRQs. We use this variable
36  * to check if someone is trying to enable/disable IRQs while they're supposed
37  * to be disabled. This shouldn't happen and we'll print some error messages in
38  * case it happens.
39  *
40  * For more, read the Documentation/power/runtime_pm.rst.
41  */
42 struct intel_runtime_pm {
43 	atomic_t wakeref_count;
44 	struct device *kdev; /* points to i915->drm.dev */
45 	bool available;
46 	bool suspended;
47 	bool irqs_enabled;
48 	bool no_wakeref_tracking;
49 
50 	/*
51 	 *  Protects access to lmem usefault list.
52 	 *  It is required, if we are outside of the runtime suspend path,
53 	 *  access to @lmem_userfault_list requires always first grabbing the
54 	 *  runtime pm, to ensure we can't race against runtime suspend.
55 	 *  Once we have that we also need to grab @lmem_userfault_lock,
56 	 *  at which point we have exclusive access.
57 	 *  The runtime suspend path is special since it doesn't really hold any locks,
58 	 *  but instead has exclusive access by virtue of all other accesses requiring
59 	 *  holding the runtime pm wakeref.
60 	 */
61 	spinlock_t lmem_userfault_lock;
62 
63 	/*
64 	 *  Keep list of userfaulted gem obj, which require to release their
65 	 *  mmap mappings at runtime suspend path.
66 	 */
67 	struct list_head lmem_userfault_list;
68 
69 	/* Manual runtime pm autosuspend delay for user GGTT/lmem mmaps */
70 	struct intel_wakeref_auto userfault_wakeref;
71 
72 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
73 	/*
74 	 * To aide detection of wakeref leaks and general misuse, we
75 	 * track all wakeref holders. With manual markup (i.e. returning
76 	 * a cookie to each rpm_get caller which they then supply to their
77 	 * paired rpm_put) we can remove corresponding pairs of and keep
78 	 * the array trimmed to active wakerefs.
79 	 */
80 	struct intel_runtime_pm_debug {
81 		spinlock_t lock;
82 
83 		depot_stack_handle_t last_acquire;
84 		depot_stack_handle_t last_release;
85 
86 		depot_stack_handle_t *owners;
87 		unsigned long count;
88 	} debug;
89 #endif
90 };
91 
92 #define BITS_PER_WAKEREF	\
93 	BITS_PER_TYPE(typeof_member(struct intel_runtime_pm, wakeref_count))
94 #define INTEL_RPM_WAKELOCK_SHIFT	(BITS_PER_WAKEREF / 2)
95 #define INTEL_RPM_WAKELOCK_BIAS		(1 << INTEL_RPM_WAKELOCK_SHIFT)
96 #define INTEL_RPM_RAW_WAKEREF_MASK	(INTEL_RPM_WAKELOCK_BIAS - 1)
97 
98 static inline int
99 intel_rpm_raw_wakeref_count(int wakeref_count)
100 {
101 	return wakeref_count & INTEL_RPM_RAW_WAKEREF_MASK;
102 }
103 
104 static inline int
105 intel_rpm_wakelock_count(int wakeref_count)
106 {
107 	return wakeref_count >> INTEL_RPM_WAKELOCK_SHIFT;
108 }
109 
110 static inline void
111 assert_rpm_device_not_suspended(struct intel_runtime_pm *rpm)
112 {
113 	WARN_ONCE(rpm->suspended,
114 		  "Device suspended during HW access\n");
115 }
116 
117 static inline void
118 __assert_rpm_raw_wakeref_held(struct intel_runtime_pm *rpm, int wakeref_count)
119 {
120 	assert_rpm_device_not_suspended(rpm);
121 	WARN_ONCE(!intel_rpm_raw_wakeref_count(wakeref_count),
122 		  "RPM raw-wakeref not held\n");
123 }
124 
125 static inline void
126 __assert_rpm_wakelock_held(struct intel_runtime_pm *rpm, int wakeref_count)
127 {
128 	__assert_rpm_raw_wakeref_held(rpm, wakeref_count);
129 	WARN_ONCE(!intel_rpm_wakelock_count(wakeref_count),
130 		  "RPM wakelock ref not held during HW access\n");
131 }
132 
133 static inline void
134 assert_rpm_raw_wakeref_held(struct intel_runtime_pm *rpm)
135 {
136 	__assert_rpm_raw_wakeref_held(rpm, atomic_read(&rpm->wakeref_count));
137 }
138 
139 static inline void
140 assert_rpm_wakelock_held(struct intel_runtime_pm *rpm)
141 {
142 	__assert_rpm_wakelock_held(rpm, atomic_read(&rpm->wakeref_count));
143 }
144 
145 /**
146  * disable_rpm_wakeref_asserts - disable the RPM assert checks
147  * @rpm: the intel_runtime_pm structure
148  *
149  * This function disable asserts that check if we hold an RPM wakelock
150  * reference, while keeping the device-not-suspended checks still enabled.
151  * It's meant to be used only in special circumstances where our rule about
152  * the wakelock refcount wrt. the device power state doesn't hold. According
153  * to this rule at any point where we access the HW or want to keep the HW in
154  * an active state we must hold an RPM wakelock reference acquired via one of
155  * the intel_runtime_pm_get() helpers. Currently there are a few special spots
156  * where this rule doesn't hold: the IRQ and suspend/resume handlers, the
157  * forcewake release timer, and the GPU RPS and hangcheck works. All other
158  * users should avoid using this function.
159  *
160  * Any calls to this function must have a symmetric call to
161  * enable_rpm_wakeref_asserts().
162  */
163 static inline void
164 disable_rpm_wakeref_asserts(struct intel_runtime_pm *rpm)
165 {
166 	atomic_add(INTEL_RPM_WAKELOCK_BIAS + 1,
167 		   &rpm->wakeref_count);
168 }
169 
170 /**
171  * enable_rpm_wakeref_asserts - re-enable the RPM assert checks
172  * @rpm: the intel_runtime_pm structure
173  *
174  * This function re-enables the RPM assert checks after disabling them with
175  * disable_rpm_wakeref_asserts. It's meant to be used only in special
176  * circumstances otherwise its use should be avoided.
177  *
178  * Any calls to this function must have a symmetric call to
179  * disable_rpm_wakeref_asserts().
180  */
181 static inline void
182 enable_rpm_wakeref_asserts(struct intel_runtime_pm *rpm)
183 {
184 	atomic_sub(INTEL_RPM_WAKELOCK_BIAS + 1,
185 		   &rpm->wakeref_count);
186 }
187 
188 void intel_runtime_pm_init_early(struct intel_runtime_pm *rpm);
189 void intel_runtime_pm_enable(struct intel_runtime_pm *rpm);
190 void intel_runtime_pm_disable(struct intel_runtime_pm *rpm);
191 void intel_runtime_pm_driver_release(struct intel_runtime_pm *rpm);
192 
193 intel_wakeref_t intel_runtime_pm_get(struct intel_runtime_pm *rpm);
194 intel_wakeref_t intel_runtime_pm_get_if_in_use(struct intel_runtime_pm *rpm);
195 intel_wakeref_t intel_runtime_pm_get_if_active(struct intel_runtime_pm *rpm);
196 intel_wakeref_t intel_runtime_pm_get_noresume(struct intel_runtime_pm *rpm);
197 intel_wakeref_t intel_runtime_pm_get_raw(struct intel_runtime_pm *rpm);
198 
199 #define with_intel_runtime_pm(rpm, wf) \
200 	for ((wf) = intel_runtime_pm_get(rpm); (wf); \
201 	     intel_runtime_pm_put((rpm), (wf)), (wf) = 0)
202 
203 #define with_intel_runtime_pm_if_in_use(rpm, wf) \
204 	for ((wf) = intel_runtime_pm_get_if_in_use(rpm); (wf); \
205 	     intel_runtime_pm_put((rpm), (wf)), (wf) = 0)
206 
207 #define with_intel_runtime_pm_if_active(rpm, wf) \
208 	for ((wf) = intel_runtime_pm_get_if_active(rpm); (wf); \
209 	     intel_runtime_pm_put((rpm), (wf)), (wf) = 0)
210 
211 void intel_runtime_pm_put_unchecked(struct intel_runtime_pm *rpm);
212 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
213 void intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref);
214 #else
215 static inline void
216 intel_runtime_pm_put(struct intel_runtime_pm *rpm, intel_wakeref_t wref)
217 {
218 	intel_runtime_pm_put_unchecked(rpm);
219 }
220 #endif
221 void intel_runtime_pm_put_raw(struct intel_runtime_pm *rpm, intel_wakeref_t wref);
222 
223 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_RUNTIME_PM)
224 void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
225 				    struct drm_printer *p);
226 #else
227 static inline void print_intel_runtime_pm_wakeref(struct intel_runtime_pm *rpm,
228 						  struct drm_printer *p)
229 {
230 }
231 #endif
232 
233 #endif /* __INTEL_RUNTIME_PM_H__ */
234