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