1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2021, Adrian Chadd <adrian@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice unmodified, this list of conditions, and the following 11 * disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 /* Driver for Qualcomm MSM entropy device. */ 29 30 #include <sys/cdefs.h> 31 __FBSDID("$FreeBSD$"); 32 33 #include <sys/param.h> 34 #include <sys/kernel.h> 35 #include <sys/malloc.h> 36 #include <sys/module.h> 37 #include <sys/sglist.h> 38 #include <sys/random.h> 39 #include <sys/stdatomic.h> 40 41 #include <machine/bus.h> 42 #include <machine/resource.h> 43 #include <sys/bus.h> 44 45 #include <dev/fdt/fdt_common.h> 46 #include <dev/ofw/ofw_bus.h> 47 #include <dev/ofw/ofw_bus_subr.h> 48 49 #include <dev/random/randomdev.h> 50 #include <dev/random/random_harvestq.h> 51 52 #include <dev/qcom_rnd/qcom_rnd_reg.h> 53 54 struct qcom_rnd_softc { 55 device_t dev; 56 int reg_rid; 57 struct resource *reg; 58 }; 59 60 static int qcom_rnd_modevent(module_t, int, void *); 61 62 static int qcom_rnd_probe(device_t); 63 static int qcom_rnd_attach(device_t); 64 static int qcom_rnd_detach(device_t); 65 66 static int qcom_rnd_harvest(struct qcom_rnd_softc *, void *, size_t *); 67 static unsigned qcom_rnd_read(void *, unsigned); 68 69 static struct random_source random_qcom_rnd = { 70 .rs_ident = "Qualcomm Entropy Adapter", 71 .rs_source = RANDOM_PURE_QUALCOMM, 72 .rs_read = qcom_rnd_read, 73 }; 74 75 /* Kludge for API limitations of random(4). */ 76 static _Atomic(struct qcom_rnd_softc *) g_qcom_rnd_softc; 77 78 static int 79 qcom_rnd_modevent(module_t mod, int type, void *unused) 80 { 81 int error; 82 83 switch (type) { 84 case MOD_LOAD: 85 case MOD_QUIESCE: 86 case MOD_UNLOAD: 87 case MOD_SHUTDOWN: 88 error = 0; 89 break; 90 default: 91 error = EOPNOTSUPP; 92 break; 93 } 94 95 return (error); 96 } 97 98 static int 99 qcom_rnd_probe(device_t dev) 100 { 101 if (! ofw_bus_status_okay(dev)) { 102 return (ENXIO); 103 } 104 105 if (ofw_bus_is_compatible(dev, "qcom,prng") == 0) { 106 return (ENXIO); 107 } 108 109 return (0); 110 } 111 112 static int 113 qcom_rnd_attach(device_t dev) 114 { 115 struct qcom_rnd_softc *sc, *exp; 116 uint32_t reg; 117 118 sc = device_get_softc(dev); 119 120 121 /* Found a compatible device! */ 122 123 sc->dev = dev; 124 125 exp = NULL; 126 if (!atomic_compare_exchange_strong_explicit(&g_qcom_rnd_softc, &exp, 127 sc, memory_order_release, memory_order_acquire)) { 128 return (ENXIO); 129 } 130 131 sc->reg_rid = 0; 132 sc->reg = bus_alloc_resource_anywhere(dev, SYS_RES_MEMORY, 133 &sc->reg_rid, 0x140, RF_ACTIVE); 134 if (sc->reg == NULL) { 135 device_printf(dev, "Couldn't allocate memory resource!\n"); 136 return (ENXIO); 137 } 138 139 device_set_desc(dev, "Qualcomm PRNG"); 140 141 /* 142 * Check to see whether the PRNG has already been setup or not. 143 */ 144 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 145 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 146 if (reg & QCOM_RND_PRNG_CONFIG_HW_ENABLE) { 147 device_printf(dev, "PRNG HW already enabled\n"); 148 } else { 149 /* 150 * Do PRNG setup and then enable it. 151 */ 152 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG); 153 reg &= QCOM_RND_PRNG_LFSR_CFG_MASK; 154 reg |= QCOM_RND_PRNG_LFSR_CFG_CLOCKS; 155 bus_write_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG, reg); 156 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 157 158 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 159 reg |= QCOM_RND_PRNG_CONFIG_HW_ENABLE; 160 bus_write_4(sc->reg, QCOM_RND_PRNG_CONFIG, reg); 161 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 162 } 163 164 random_source_register(&random_qcom_rnd); 165 return (0); 166 167 } 168 169 static int 170 qcom_rnd_detach(device_t dev) 171 { 172 struct qcom_rnd_softc *sc; 173 174 sc = device_get_softc(dev); 175 KASSERT( 176 atomic_load_explicit(&g_qcom_rnd_softc, memory_order_acquire) == sc, 177 ("only one global instance at a time")); 178 179 random_source_deregister(&random_qcom_rnd); 180 if (sc->reg != NULL) { 181 bus_release_resource(sc->dev, SYS_RES_MEMORY, sc->reg_rid, sc->reg); 182 } 183 atomic_store_explicit(&g_qcom_rnd_softc, NULL, memory_order_release); 184 return (0); 185 } 186 187 static int 188 qcom_rnd_harvest(struct qcom_rnd_softc *sc, void *buf, size_t *sz) 189 { 190 /* 191 * Add data to buf until we either run out of entropy or we 192 * fill the buffer. 193 * 194 * Note - be mindful of the provided buffer size; we're reading 195 * 4 bytes at a time but we only want to supply up to the max 196 * buffer size, so don't write past it! 197 */ 198 size_t rz = 0; 199 uint32_t reg; 200 201 while (rz < *sz) { 202 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 203 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_STATUS); 204 if ((reg & QCOM_RND_PRNG_STATUS_DATA_AVAIL) == 0) 205 break; 206 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_DATA_OUT); 207 memcpy(((char *) buf) + rz, ®, sizeof(uint32_t)); 208 rz += sizeof(uint32_t); 209 } 210 211 if (rz == 0) 212 return (EAGAIN); 213 *sz = rz; 214 return (0); 215 } 216 217 static unsigned 218 qcom_rnd_read(void *buf, unsigned usz) 219 { 220 struct qcom_rnd_softc *sc; 221 size_t sz; 222 int error; 223 224 sc = g_qcom_rnd_softc; 225 if (sc == NULL) 226 return (0); 227 228 sz = usz; 229 error = qcom_rnd_harvest(sc, buf, &sz); 230 if (error != 0) 231 return (0); 232 233 return (sz); 234 } 235 236 static device_method_t qcom_rnd_methods[] = { 237 /* Device methods. */ 238 DEVMETHOD(device_probe, qcom_rnd_probe), 239 DEVMETHOD(device_attach, qcom_rnd_attach), 240 DEVMETHOD(device_detach, qcom_rnd_detach), 241 242 DEVMETHOD_END 243 }; 244 245 static driver_t qcom_rnd_driver = { 246 "qcom_rnd", 247 qcom_rnd_methods, 248 sizeof(struct qcom_rnd_softc) 249 }; 250 251 DRIVER_MODULE(qcom_rnd_random, simplebus, qcom_rnd_driver, 252 qcom_rnd_modevent, 0); 253 DRIVER_MODULE(qcom_rnd_random, ofwbus, qcom_rnd_driver, 254 qcom_rnd_modevent, 0); 255 MODULE_DEPEND(qcom_rnd_random, random_device, 1, 1, 1); 256 MODULE_VERSION(qcom_rnd_random, 1); 257