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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 | ||
a979a6aa ZL |
43 | if (ret) |
44 | goto err_add_consumer; | |
45 | ||
46 | ret = cons->add_producer(cons, prod); | |
47 | if (ret) | |
48 | goto err_add_producer; | |
f73f8173 AW |
49 | |
50 | if (cons->start) | |
51 | cons->start(cons); | |
52 | if (prod->start) | |
53 | prod->start(prod); | |
a979a6aa ZL |
54 | err_add_producer: |
55 | if (prod->del_consumer) | |
56 | prod->del_consumer(prod, cons); | |
57 | err_add_consumer: | |
f73f8173 AW |
58 | return ret; |
59 | } | |
60 | ||
61 | /* @lock must be held when calling disconnect */ | |
62 | static void __disconnect(struct irq_bypass_producer *prod, | |
63 | struct irq_bypass_consumer *cons) | |
64 | { | |
65 | if (prod->stop) | |
66 | prod->stop(prod); | |
67 | if (cons->stop) | |
68 | cons->stop(cons); | |
69 | ||
70 | cons->del_producer(cons, prod); | |
71 | ||
72 | if (prod->del_consumer) | |
73 | prod->del_consumer(prod, cons); | |
74 | ||
75 | if (cons->start) | |
76 | cons->start(cons); | |
77 | if (prod->start) | |
78 | prod->start(prod); | |
79 | } | |
80 | ||
81 | /** | |
82 | * irq_bypass_register_producer - register IRQ bypass producer | |
83 | * @producer: pointer to producer structure | |
84 | * | |
85 | * Add the provided IRQ producer to the list of producers and connect | |
86 | * with any matching token found on the IRQ consumers list. | |
87 | */ | |
88 | int irq_bypass_register_producer(struct irq_bypass_producer *producer) | |
89 | { | |
90 | struct irq_bypass_producer *tmp; | |
91 | struct irq_bypass_consumer *consumer; | |
bbfdafa8 | 92 | int ret; |
f73f8173 | 93 | |
b52f3ed0 AW |
94 | if (!producer->token) |
95 | return -EINVAL; | |
96 | ||
f73f8173 AW |
97 | might_sleep(); |
98 | ||
99 | if (!try_module_get(THIS_MODULE)) | |
100 | return -ENODEV; | |
101 | ||
102 | mutex_lock(&lock); | |
103 | ||
104 | list_for_each_entry(tmp, &producers, node) { | |
105 | if (tmp->token == producer->token) { | |
bbfdafa8 ML |
106 | ret = -EBUSY; |
107 | goto out_err; | |
f73f8173 AW |
108 | } |
109 | } | |
110 | ||
111 | list_for_each_entry(consumer, &consumers, node) { | |
112 | if (consumer->token == producer->token) { | |
bbfdafa8 ML |
113 | ret = __connect(producer, consumer); |
114 | if (ret) | |
115 | goto out_err; | |
f73f8173 AW |
116 | break; |
117 | } | |
118 | } | |
119 | ||
120 | list_add(&producer->node, &producers); | |
121 | ||
122 | mutex_unlock(&lock); | |
123 | ||
124 | return 0; | |
bbfdafa8 ML |
125 | out_err: |
126 | mutex_unlock(&lock); | |
127 | module_put(THIS_MODULE); | |
128 | return ret; | |
f73f8173 AW |
129 | } |
130 | EXPORT_SYMBOL_GPL(irq_bypass_register_producer); | |
131 | ||
132 | /** | |
133 | * irq_bypass_unregister_producer - unregister IRQ bypass producer | |
134 | * @producer: pointer to producer structure | |
135 | * | |
136 | * Remove a previously registered IRQ producer from the list of producers | |
137 | * and disconnect it from any connected IRQ consumer. | |
138 | */ | |
139 | void irq_bypass_unregister_producer(struct irq_bypass_producer *producer) | |
140 | { | |
141 | struct irq_bypass_producer *tmp; | |
142 | struct irq_bypass_consumer *consumer; | |
143 | ||
b52f3ed0 AW |
144 | if (!producer->token) |
145 | return; | |
146 | ||
f73f8173 AW |
147 | might_sleep(); |
148 | ||
149 | if (!try_module_get(THIS_MODULE)) | |
150 | return; /* nothing in the list anyway */ | |
151 | ||
152 | mutex_lock(&lock); | |
153 | ||
154 | list_for_each_entry(tmp, &producers, node) { | |
155 | if (tmp->token != producer->token) | |
156 | continue; | |
157 | ||
158 | list_for_each_entry(consumer, &consumers, node) { | |
159 | if (consumer->token == producer->token) { | |
160 | __disconnect(producer, consumer); | |
161 | break; | |
162 | } | |
163 | } | |
164 | ||
165 | list_del(&producer->node); | |
166 | module_put(THIS_MODULE); | |
167 | break; | |
168 | } | |
169 | ||
170 | mutex_unlock(&lock); | |
171 | ||
172 | module_put(THIS_MODULE); | |
173 | } | |
174 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_producer); | |
175 | ||
176 | /** | |
177 | * irq_bypass_register_consumer - register IRQ bypass consumer | |
178 | * @consumer: pointer to consumer structure | |
179 | * | |
180 | * Add the provided IRQ consumer to the list of consumers and connect | |
181 | * with any matching token found on the IRQ producer list. | |
182 | */ | |
183 | int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer) | |
184 | { | |
185 | struct irq_bypass_consumer *tmp; | |
186 | struct irq_bypass_producer *producer; | |
8262fe85 | 187 | int ret; |
f73f8173 | 188 | |
b52f3ed0 AW |
189 | if (!consumer->token || |
190 | !consumer->add_producer || !consumer->del_producer) | |
f73f8173 AW |
191 | return -EINVAL; |
192 | ||
193 | might_sleep(); | |
194 | ||
195 | if (!try_module_get(THIS_MODULE)) | |
196 | return -ENODEV; | |
197 | ||
198 | mutex_lock(&lock); | |
199 | ||
200 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 201 | if (tmp->token == consumer->token || tmp == consumer) { |
8262fe85 ML |
202 | ret = -EBUSY; |
203 | goto out_err; | |
f73f8173 AW |
204 | } |
205 | } | |
206 | ||
207 | list_for_each_entry(producer, &producers, node) { | |
208 | if (producer->token == consumer->token) { | |
8262fe85 ML |
209 | ret = __connect(producer, consumer); |
210 | if (ret) | |
211 | goto out_err; | |
f73f8173 AW |
212 | break; |
213 | } | |
214 | } | |
215 | ||
216 | list_add(&consumer->node, &consumers); | |
217 | ||
218 | mutex_unlock(&lock); | |
219 | ||
220 | return 0; | |
8262fe85 ML |
221 | out_err: |
222 | mutex_unlock(&lock); | |
223 | module_put(THIS_MODULE); | |
224 | return ret; | |
f73f8173 AW |
225 | } |
226 | EXPORT_SYMBOL_GPL(irq_bypass_register_consumer); | |
227 | ||
228 | /** | |
229 | * irq_bypass_unregister_consumer - unregister IRQ bypass consumer | |
230 | * @consumer: pointer to consumer structure | |
231 | * | |
232 | * Remove a previously registered IRQ consumer from the list of consumers | |
233 | * and disconnect it from any connected IRQ producer. | |
234 | */ | |
235 | void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer) | |
236 | { | |
237 | struct irq_bypass_consumer *tmp; | |
238 | struct irq_bypass_producer *producer; | |
239 | ||
b52f3ed0 AW |
240 | if (!consumer->token) |
241 | return; | |
242 | ||
f73f8173 AW |
243 | might_sleep(); |
244 | ||
245 | if (!try_module_get(THIS_MODULE)) | |
246 | return; /* nothing in the list anyway */ | |
247 | ||
248 | mutex_lock(&lock); | |
249 | ||
250 | list_for_each_entry(tmp, &consumers, node) { | |
4f3dbdf4 | 251 | if (tmp != consumer) |
f73f8173 AW |
252 | continue; |
253 | ||
254 | list_for_each_entry(producer, &producers, node) { | |
255 | if (producer->token == consumer->token) { | |
256 | __disconnect(producer, consumer); | |
257 | break; | |
258 | } | |
259 | } | |
260 | ||
261 | list_del(&consumer->node); | |
262 | module_put(THIS_MODULE); | |
263 | break; | |
264 | } | |
265 | ||
266 | mutex_unlock(&lock); | |
267 | ||
268 | module_put(THIS_MODULE); | |
269 | } | |
270 | EXPORT_SYMBOL_GPL(irq_bypass_unregister_consumer); |