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