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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
f73f8173 AW |
2 | /* |
3 | * IRQ offload/bypass manager | |
4 | * | |
5 | * Copyright (C) 2015 Red Hat, Inc. | |
6 | * Copyright (c) 2015 Linaro Ltd. | |
7 | * | |
f73f8173 AW |
8 | * Various virtualization hardware acceleration techniques allow bypassing or |
9 | * offloading interrupts received from devices around the host kernel. Posted | |
10 | * Interrupts on Intel VT-d systems can allow interrupts to be received | |
11 | * directly by a virtual machine. ARM IRQ Forwarding allows forwarded physical | |
12 | * interrupts to be directly deactivated by the guest. This manager allows | |
13 | * interrupt producers and consumers to find each other to enable this sort of | |
14 | * bypass. | |
15 | */ | |
16 | ||
17 | #include <linux/irqbypass.h> | |
18 | #include <linux/list.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/mutex.h> | |
21 | ||
22 | MODULE_LICENSE("GPL v2"); | |
23 | MODULE_DESCRIPTION("IRQ bypass manager utility module"); | |
24 | ||
25 | static LIST_HEAD(producers); | |
26 | static LIST_HEAD(consumers); | |
27 | static DEFINE_MUTEX(lock); | |
28 | ||
29 | /* @lock must be held when calling connect */ | |
30 | static int __connect(struct irq_bypass_producer *prod, | |
31 | struct irq_bypass_consumer *cons) | |
32 | { | |
33 | int ret = 0; | |
34 | ||
35 | if (prod->stop) | |
36 | prod->stop(prod); | |
37 | if (cons->stop) | |
38 | cons->stop(cons); | |
39 | ||
40 | if (prod->add_consumer) | |
41 | ret = prod->add_consumer(prod, cons); | |
42 | ||
43 | if (!ret) { | |
44 | ret = cons->add_producer(cons, prod); | |
45 | if (ret && prod->del_consumer) | |
46 | prod->del_consumer(prod, cons); | |
47 | } | |
48 | ||
49 | if (cons->start) | |
50 | cons->start(cons); | |
51 | if (prod->start) | |
52 | prod->start(prod); | |
53 | ||
54 | return ret; | |
55 | } | |
56 | ||
57 | /* @lock must be held when calling disconnect */ | |
58 | static void __disconnect(struct irq_bypass_producer *prod, | |
59 | struct irq_bypass_consumer *cons) | |
60 | { | |
61 | if (prod->stop) | |
62 | prod->stop(prod); | |
63 | if (cons->stop) | |
64 | cons->stop(cons); | |
65 | ||
66 | cons->del_producer(cons, prod); | |
67 | ||
68 | if (prod->del_consumer) | |
69 | prod->del_consumer(prod, cons); | |
70 | ||
71 | if (cons->start) | |
72 | cons->start(cons); | |
73 | if (prod->start) | |
74 | prod->start(prod); | |
75 | } | |
76 | ||
77 | /** | |
78 | * irq_bypass_register_producer - register IRQ bypass producer | |
79 | * @producer: pointer to producer structure | |
80 | * | |
81 | * Add the provided IRQ producer to the list of producers and connect | |
82 | * with any matching token found on the IRQ consumers list. | |
83 | */ | |
84 | int irq_bypass_register_producer(struct irq_bypass_producer *producer) | |
85 | { | |
86 | struct irq_bypass_producer *tmp; | |
87 | struct irq_bypass_consumer *consumer; | |
88 | ||
b52f3ed0 AW |
89 | if (!producer->token) |
90 | return -EINVAL; | |
91 | ||
f73f8173 AW |
92 | might_sleep(); |
93 | ||
94 | if (!try_module_get(THIS_MODULE)) | |
95 | return -ENODEV; | |
96 | ||
97 | mutex_lock(&lock); | |
98 | ||
99 | list_for_each_entry(tmp, &producers, node) { | |
100 | if (tmp->token == producer->token) { | |
101 | mutex_unlock(&lock); | |
102 | module_put(THIS_MODULE); | |
103 | return -EBUSY; | |
104 | } | |
105 | } | |
106 | ||
107 | list_for_each_entry(consumer, &consumers, node) { | |
108 | if (consumer->token == producer->token) { | |
109 | int ret = __connect(producer, consumer); | |
110 | if (ret) { | |
111 | mutex_unlock(&lock); | |
112 | module_put(THIS_MODULE); | |
113 | return ret; | |
114 | } | |
115 | break; | |
116 | } | |
117 | } | |
118 | ||
119 | list_add(&producer->node, &producers); | |
120 | ||
121 | mutex_unlock(&lock); | |
122 | ||
123 | return 0; | |
124 | } | |
125 | EXPORT_SYMBOL_GPL(irq_bypass_register_producer); | |
126 | ||
127 | /** | |
128 | * irq_bypass_unregister_producer - unregister IRQ bypass producer | |
129 | * @producer: pointer to producer structure | |
130 | * | |
131 | * Remove a previously registered IRQ producer from the list of producers | |
132 | * and disconnect it from any connected IRQ consumer. | |
133 | */ | |
134 | void irq_bypass_unregister_producer(struct irq_bypass_producer *producer) | |
135 | { | |
136 | struct irq_bypass_producer *tmp; | |
137 | struct irq_bypass_consumer *consumer; | |
138 | ||
b52f3ed0 AW |
139 | if (!producer->token) |
140 | return; | |
141 | ||
f73f8173 AW |
142 | might_sleep(); |
143 | ||
144 | if (!try_module_get(THIS_MODULE)) | |
145 | return; /* nothing in the list anyway */ | |
146 | ||
147 | mutex_lock(&lock); | |
148 | ||
149 | list_for_each_entry(tmp, &producers, node) { | |
150 | if (tmp->token != producer->token) | |
151 | continue; | |
152 | ||
153 | list_for_each_entry(consumer, &consumers, node) { | |
154 | if (consumer->token == producer->token) { | |
155 | __disconnect(producer, consumer); | |
156 | break; | |
157 | } | |
158 | } | |
159 | ||
160 | list_del(&producer->node); | |
161 | module_put(THIS_MODULE); | |
162 | break; | |
163 | } | |
164 | ||
165 | mutex_unlock(&lock); | |
166 | ||
167 | module_put(THIS_MODULE); | |
168 | } | |
169 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer); | |
170 | ||
171 | /** | |
172 | * irq_bypass_register_consumer - register IRQ bypass consumer | |
173 | * @consumer: pointer to consumer structure | |
174 | * | |
175 | * Add the provided IRQ consumer to the list of consumers and connect | |
176 | * with any matching token found on the IRQ producer list. | |
177 | */ | |
178 | int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer) | |
179 | { | |
180 | struct irq_bypass_consumer *tmp; | |
181 | struct irq_bypass_producer *producer; | |
182 | ||
b52f3ed0 AW |
183 | if (!consumer->token || |
184 | !consumer->add_producer || !consumer->del_producer) | |
f73f8173 AW |
185 | return -EINVAL; |
186 | ||
187 | might_sleep(); | |
188 | ||
189 | if (!try_module_get(THIS_MODULE)) | |
190 | return -ENODEV; | |
191 | ||
192 | mutex_lock(&lock); | |
193 | ||
194 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 195 | if (tmp->token == consumer->token || tmp == consumer) { |
f73f8173 AW |
196 | mutex_unlock(&lock); |
197 | module_put(THIS_MODULE); | |
198 | return -EBUSY; | |
199 | } | |
200 | } | |
201 | ||
202 | list_for_each_entry(producer, &producers, node) { | |
203 | if (producer->token == consumer->token) { | |
204 | int ret = __connect(producer, consumer); | |
205 | if (ret) { | |
206 | mutex_unlock(&lock); | |
207 | module_put(THIS_MODULE); | |
208 | return ret; | |
209 | } | |
210 | break; | |
211 | } | |
212 | } | |
213 | ||
214 | list_add(&consumer->node, &consumers); | |
215 | ||
216 | mutex_unlock(&lock); | |
217 | ||
218 | return 0; | |
219 | } | |
220 | EXPORT_SYMBOL_GPL(irq_bypass_register_consumer); | |
221 | ||
222 | /** | |
223 | * irq_bypass_unregister_consumer - unregister IRQ bypass consumer | |
224 | * @consumer: pointer to consumer structure | |
225 | * | |
226 | * Remove a previously registered IRQ consumer from the list of consumers | |
227 | * and disconnect it from any connected IRQ producer. | |
228 | */ | |
229 | void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer) | |
230 | { | |
231 | struct irq_bypass_consumer *tmp; | |
232 | struct irq_bypass_producer *producer; | |
233 | ||
b52f3ed0 AW |
234 | if (!consumer->token) |
235 | return; | |
236 | ||
f73f8173 AW |
237 | might_sleep(); |
238 | ||
239 | if (!try_module_get(THIS_MODULE)) | |
240 | return; /* nothing in the list anyway */ | |
241 | ||
242 | mutex_lock(&lock); | |
243 | ||
244 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 245 | if (tmp != consumer) |
f73f8173 AW |
246 | continue; |
247 | ||
248 | list_for_each_entry(producer, &producers, node) { | |
249 | if (producer->token == consumer->token) { | |
250 | __disconnect(producer, consumer); | |
251 | break; | |
252 | } | |
253 | } | |
254 | ||
255 | list_del(&consumer->node); | |
256 | module_put(THIS_MODULE); | |
257 | break; | |
258 | } | |
259 | ||
260 | mutex_unlock(&lock); | |
261 | ||
262 | module_put(THIS_MODULE); | |
263 | } | |
264 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer); |