1 /*-
2 * Copyright (c) 2013, Bryan Venteicher <bryanv@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice unmodified, this list of conditions, and the following
10 * disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 /* Driver for VirtIO entropy device. */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/kernel.h>
34 #include <sys/module.h>
35 #include <sys/sglist.h>
36 #include <sys/callout.h>
37 #include <sys/random.h>
38
39 #include <machine/bus.h>
40 #include <machine/resource.h>
41 #include <sys/bus.h>
42
43 #include <dev/virtio/virtio.h>
44 #include <dev/virtio/virtqueue.h>
45
46 struct vtrnd_softc {
47 device_t vtrnd_dev;
48 uint64_t vtrnd_features;
49 struct callout vtrnd_callout;
50 struct virtqueue *vtrnd_vq;
51 };
52
53 static int vtrnd_modevent(module_t, int, void *);
54
55 static int vtrnd_probe(device_t);
56 static int vtrnd_attach(device_t);
57 static int vtrnd_detach(device_t);
58
59 static void vtrnd_negotiate_features(struct vtrnd_softc *);
60 static int vtrnd_alloc_virtqueue(struct vtrnd_softc *);
61 static void vtrnd_harvest(struct vtrnd_softc *);
62 static void vtrnd_timer(void *);
63
64 #define VTRND_FEATURES 0
65
66 static struct virtio_feature_desc vtrnd_feature_desc[] = {
67 { 0, NULL }
68 };
69
70 static device_method_t vtrnd_methods[] = {
71 /* Device methods. */
72 DEVMETHOD(device_probe, vtrnd_probe),
73 DEVMETHOD(device_attach, vtrnd_attach),
74 DEVMETHOD(device_detach, vtrnd_detach),
75
76 DEVMETHOD_END
77 };
78
79 static driver_t vtrnd_driver = {
80 "vtrnd",
81 vtrnd_methods,
82 sizeof(struct vtrnd_softc)
83 };
84 static devclass_t vtrnd_devclass;
85
86 DRIVER_MODULE(virtio_random, virtio_pci, vtrnd_driver, vtrnd_devclass,
87 vtrnd_modevent, 0);
88 MODULE_VERSION(virtio_random, 1);
89 MODULE_DEPEND(virtio_random, virtio, 1, 1, 1);
90
91 static int
vtrnd_modevent(module_t mod,int type,void * unused)92 vtrnd_modevent(module_t mod, int type, void *unused)
93 {
94 int error;
95
96 switch (type) {
97 case MOD_LOAD:
98 case MOD_QUIESCE:
99 case MOD_UNLOAD:
100 case MOD_SHUTDOWN:
101 error = 0;
102 break;
103 default:
104 error = EOPNOTSUPP;
105 break;
106 }
107
108 return (error);
109 }
110
111 static int
vtrnd_probe(device_t dev)112 vtrnd_probe(device_t dev)
113 {
114
115 if (virtio_get_device_type(dev) != VIRTIO_ID_ENTROPY)
116 return (ENXIO);
117
118 device_set_desc(dev, "VirtIO Entropy Adapter");
119
120 return (BUS_PROBE_DEFAULT);
121 }
122
123 static int
vtrnd_attach(device_t dev)124 vtrnd_attach(device_t dev)
125 {
126 struct vtrnd_softc *sc;
127 int error;
128
129 sc = device_get_softc(dev);
130 sc->vtrnd_dev = dev;
131
132 callout_init(&sc->vtrnd_callout, 1);
133
134 virtio_set_feature_desc(dev, vtrnd_feature_desc);
135 vtrnd_negotiate_features(sc);
136
137 error = vtrnd_alloc_virtqueue(sc);
138 if (error) {
139 device_printf(dev, "cannot allocate virtqueue\n");
140 goto fail;
141 }
142
143 callout_reset(&sc->vtrnd_callout, 5 * hz, vtrnd_timer, sc);
144
145 fail:
146 if (error)
147 vtrnd_detach(dev);
148
149 return (error);
150 }
151
152 static int
vtrnd_detach(device_t dev)153 vtrnd_detach(device_t dev)
154 {
155 struct vtrnd_softc *sc;
156
157 sc = device_get_softc(dev);
158
159 callout_drain(&sc->vtrnd_callout);
160
161 return (0);
162 }
163
164 static void
vtrnd_negotiate_features(struct vtrnd_softc * sc)165 vtrnd_negotiate_features(struct vtrnd_softc *sc)
166 {
167 device_t dev;
168 uint64_t features;
169
170 dev = sc->vtrnd_dev;
171 features = VTRND_FEATURES;
172
173 sc->vtrnd_features = virtio_negotiate_features(dev, features);
174 }
175
176 static int
vtrnd_alloc_virtqueue(struct vtrnd_softc * sc)177 vtrnd_alloc_virtqueue(struct vtrnd_softc *sc)
178 {
179 device_t dev;
180 struct vq_alloc_info vq_info;
181
182 dev = sc->vtrnd_dev;
183
184 VQ_ALLOC_INFO_INIT(&vq_info, 0, NULL, sc, &sc->vtrnd_vq,
185 "%s request", device_get_nameunit(dev));
186
187 return (virtio_alloc_virtqueues(dev, 0, 1, &vq_info));
188 }
189
190 static void
vtrnd_harvest(struct vtrnd_softc * sc)191 vtrnd_harvest(struct vtrnd_softc *sc)
192 {
193 struct sglist_seg segs[1];
194 struct sglist sg;
195 struct virtqueue *vq;
196 uint32_t value;
197 int error;
198
199 vq = sc->vtrnd_vq;
200
201 sglist_init(&sg, 1, segs);
202 error = sglist_append(&sg, &value, sizeof(value));
203 KASSERT(error == 0 && sg.sg_nseg == 1,
204 ("%s: error %d adding buffer to sglist", __func__, error));
205
206 if (!virtqueue_empty(vq))
207 return;
208 if (virtqueue_enqueue(vq, &value, &sg, 0, 1) != 0)
209 return;
210
211 /*
212 * Poll for the response, but the command is likely already
213 * done when we return from the notify.
214 */
215 virtqueue_notify(vq);
216 virtqueue_poll(vq, NULL);
217
218 random_harvest_queue(&value, sizeof(value), sizeof(value) * NBBY / 2,
219 RANDOM_PURE_VIRTIO);
220 }
221
222 static void
vtrnd_timer(void * xsc)223 vtrnd_timer(void *xsc)
224 {
225 struct vtrnd_softc *sc;
226
227 sc = xsc;
228
229 vtrnd_harvest(sc);
230 callout_schedule(&sc->vtrnd_callout, 5 * hz);
231 }
232