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 device_t vtrnd_dev; 50 uint64_t vtrnd_features; 51 struct callout vtrnd_callout; 52 struct virtqueue *vtrnd_vq; 53 }; 54 55 static int vtrnd_modevent(module_t, int, void *); 56 57 static int vtrnd_probe(device_t); 58 static int vtrnd_attach(device_t); 59 static int vtrnd_detach(device_t); 60 61 static void vtrnd_negotiate_features(struct vtrnd_softc *); 62 static int vtrnd_alloc_virtqueue(struct vtrnd_softc *); 63 static void vtrnd_harvest(struct vtrnd_softc *); 64 static void vtrnd_timer(void *); 65 66 #define VTRND_FEATURES 0 67 68 static struct virtio_feature_desc vtrnd_feature_desc[] = { 69 { 0, NULL } 70 }; 71 72 static device_method_t vtrnd_methods[] = { 73 /* Device methods. */ 74 DEVMETHOD(device_probe, vtrnd_probe), 75 DEVMETHOD(device_attach, vtrnd_attach), 76 DEVMETHOD(device_detach, vtrnd_detach), 77 78 DEVMETHOD_END 79 }; 80 81 static driver_t vtrnd_driver = { 82 "vtrnd", 83 vtrnd_methods, 84 sizeof(struct vtrnd_softc) 85 }; 86 static devclass_t vtrnd_devclass; 87 88 DRIVER_MODULE(virtio_random, virtio_pci, vtrnd_driver, vtrnd_devclass, 89 vtrnd_modevent, 0); 90 MODULE_VERSION(virtio_random, 1); 91 MODULE_DEPEND(virtio_random, virtio, 1, 1, 1); 92 93 static int 94 vtrnd_modevent(module_t mod, int type, void *unused) 95 { 96 int error; 97 98 switch (type) { 99 case MOD_LOAD: 100 case MOD_QUIESCE: 101 case MOD_UNLOAD: 102 case MOD_SHUTDOWN: 103 error = 0; 104 break; 105 default: 106 error = EOPNOTSUPP; 107 break; 108 } 109 110 return (error); 111 } 112 113 static int 114 vtrnd_probe(device_t dev) 115 { 116 117 if (virtio_get_device_type(dev) != VIRTIO_ID_ENTROPY) 118 return (ENXIO); 119 120 device_set_desc(dev, "VirtIO Entropy Adapter"); 121 122 return (BUS_PROBE_DEFAULT); 123 } 124 125 static int 126 vtrnd_attach(device_t dev) 127 { 128 struct vtrnd_softc *sc; 129 int error; 130 131 sc = device_get_softc(dev); 132 sc->vtrnd_dev = dev; 133 134 callout_init(&sc->vtrnd_callout, 1); 135 136 virtio_set_feature_desc(dev, vtrnd_feature_desc); 137 vtrnd_negotiate_features(sc); 138 139 error = vtrnd_alloc_virtqueue(sc); 140 if (error) { 141 device_printf(dev, "cannot allocate virtqueue\n"); 142 goto fail; 143 } 144 145 callout_reset(&sc->vtrnd_callout, 5 * hz, vtrnd_timer, sc); 146 147 fail: 148 if (error) 149 vtrnd_detach(dev); 150 151 return (error); 152 } 153 154 static int 155 vtrnd_detach(device_t dev) 156 { 157 struct vtrnd_softc *sc; 158 159 sc = device_get_softc(dev); 160 161 callout_drain(&sc->vtrnd_callout); 162 163 return (0); 164 } 165 166 static void 167 vtrnd_negotiate_features(struct vtrnd_softc *sc) 168 { 169 device_t dev; 170 uint64_t features; 171 172 dev = sc->vtrnd_dev; 173 features = VTRND_FEATURES; 174 175 sc->vtrnd_features = virtio_negotiate_features(dev, features); 176 } 177 178 static int 179 vtrnd_alloc_virtqueue(struct vtrnd_softc *sc) 180 { 181 device_t dev; 182 struct vq_alloc_info vq_info; 183 184 dev = sc->vtrnd_dev; 185 186 VQ_ALLOC_INFO_INIT(&vq_info, 0, NULL, sc, &sc->vtrnd_vq, 187 "%s request", device_get_nameunit(dev)); 188 189 return (virtio_alloc_virtqueues(dev, 0, 1, &vq_info)); 190 } 191 192 static void 193 vtrnd_harvest(struct vtrnd_softc *sc) 194 { 195 struct sglist_seg segs[1]; 196 struct sglist sg; 197 struct virtqueue *vq; 198 uint32_t value; 199 int error; 200 201 vq = sc->vtrnd_vq; 202 203 sglist_init(&sg, 1, segs); 204 error = sglist_append(&sg, &value, sizeof(value)); 205 KASSERT(error == 0 && sg.sg_nseg == 1, 206 ("%s: error %d adding buffer to sglist", __func__, error)); 207 208 if (!virtqueue_empty(vq)) 209 return; 210 if (virtqueue_enqueue(vq, &value, &sg, 0, 1) != 0) 211 return; 212 213 /* 214 * Poll for the response, but the command is likely already 215 * done when we return from the notify. 216 */ 217 virtqueue_notify(vq); 218 virtqueue_poll(vq, NULL); 219 220 random_harvest_queue(&value, sizeof(value), RANDOM_PURE_VIRTIO); 221 } 222 223 static void 224 vtrnd_timer(void *xsc) 225 { 226 struct vtrnd_softc *sc; 227 228 sc = xsc; 229 230 vtrnd_harvest(sc); 231 callout_schedule(&sc->vtrnd_callout, 5 * hz); 232 } 233