1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 #include <sys/param.h> 32 #include <sys/kernel.h> 33 #include <sys/malloc.h> 34 #include <sys/module.h> 35 #include <sys/sglist.h> 36 #include <sys/random.h> 37 #include <sys/stdatomic.h> 38 39 #include <machine/bus.h> 40 #include <machine/resource.h> 41 #include <sys/bus.h> 42 43 #include <dev/fdt/fdt_common.h> 44 #include <dev/ofw/ofw_bus.h> 45 #include <dev/ofw/ofw_bus_subr.h> 46 47 #include <dev/random/randomdev.h> 48 #include <dev/random/random_harvestq.h> 49 50 #include <dev/qcom_rnd/qcom_rnd_reg.h> 51 52 struct qcom_rnd_softc { 53 device_t dev; 54 int reg_rid; 55 struct resource *reg; 56 }; 57 58 static int qcom_rnd_modevent(module_t, int, void *); 59 60 static int qcom_rnd_probe(device_t); 61 static int qcom_rnd_attach(device_t); 62 static int qcom_rnd_detach(device_t); 63 64 static int qcom_rnd_harvest(struct qcom_rnd_softc *, void *, size_t *); 65 static unsigned qcom_rnd_read(void *, unsigned); 66 67 static struct random_source random_qcom_rnd = { 68 .rs_ident = "Qualcomm Entropy Adapter", 69 .rs_source = RANDOM_PURE_QUALCOMM, 70 .rs_read = qcom_rnd_read, 71 }; 72 73 /* Kludge for API limitations of random(4). */ 74 static _Atomic(struct qcom_rnd_softc *) g_qcom_rnd_softc; 75 76 static int 77 qcom_rnd_modevent(module_t mod, int type, void *unused) 78 { 79 int error; 80 81 switch (type) { 82 case MOD_LOAD: 83 case MOD_QUIESCE: 84 case MOD_UNLOAD: 85 case MOD_SHUTDOWN: 86 error = 0; 87 break; 88 default: 89 error = EOPNOTSUPP; 90 break; 91 } 92 93 return (error); 94 } 95 96 static int 97 qcom_rnd_probe(device_t dev) 98 { 99 if (! ofw_bus_status_okay(dev)) { 100 return (ENXIO); 101 } 102 103 if (ofw_bus_is_compatible(dev, "qcom,prng") == 0) { 104 return (ENXIO); 105 } 106 107 return (0); 108 } 109 110 static int 111 qcom_rnd_attach(device_t dev) 112 { 113 struct qcom_rnd_softc *sc, *exp; 114 uint32_t reg; 115 116 sc = device_get_softc(dev); 117 118 119 /* Found a compatible device! */ 120 121 sc->dev = dev; 122 123 exp = NULL; 124 if (!atomic_compare_exchange_strong_explicit(&g_qcom_rnd_softc, &exp, 125 sc, memory_order_release, memory_order_acquire)) { 126 return (ENXIO); 127 } 128 129 sc->reg_rid = 0; 130 sc->reg = bus_alloc_resource_anywhere(dev, SYS_RES_MEMORY, 131 &sc->reg_rid, 0x140, RF_ACTIVE); 132 if (sc->reg == NULL) { 133 device_printf(dev, "Couldn't allocate memory resource!\n"); 134 return (ENXIO); 135 } 136 137 device_set_desc(dev, "Qualcomm PRNG"); 138 139 /* 140 * Check to see whether the PRNG has already been setup or not. 141 */ 142 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 143 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 144 if (reg & QCOM_RND_PRNG_CONFIG_HW_ENABLE) { 145 device_printf(dev, "PRNG HW already enabled\n"); 146 } else { 147 /* 148 * Do PRNG setup and then enable it. 149 */ 150 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG); 151 reg &= QCOM_RND_PRNG_LFSR_CFG_MASK; 152 reg |= QCOM_RND_PRNG_LFSR_CFG_CLOCKS; 153 bus_write_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG, reg); 154 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 155 156 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 157 reg |= QCOM_RND_PRNG_CONFIG_HW_ENABLE; 158 bus_write_4(sc->reg, QCOM_RND_PRNG_CONFIG, reg); 159 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 160 } 161 162 random_source_register(&random_qcom_rnd); 163 return (0); 164 165 } 166 167 static int 168 qcom_rnd_detach(device_t dev) 169 { 170 struct qcom_rnd_softc *sc; 171 172 sc = device_get_softc(dev); 173 KASSERT( 174 atomic_load_explicit(&g_qcom_rnd_softc, memory_order_acquire) == sc, 175 ("only one global instance at a time")); 176 177 random_source_deregister(&random_qcom_rnd); 178 if (sc->reg != NULL) { 179 bus_release_resource(sc->dev, SYS_RES_MEMORY, sc->reg_rid, sc->reg); 180 } 181 atomic_store_explicit(&g_qcom_rnd_softc, NULL, memory_order_release); 182 return (0); 183 } 184 185 static int 186 qcom_rnd_harvest(struct qcom_rnd_softc *sc, void *buf, size_t *sz) 187 { 188 /* 189 * Add data to buf until we either run out of entropy or we 190 * fill the buffer. 191 * 192 * Note - be mindful of the provided buffer size; we're reading 193 * 4 bytes at a time but we only want to supply up to the max 194 * buffer size, so don't write past it! 195 */ 196 size_t rz = 0; 197 uint32_t reg; 198 199 while (rz < *sz) { 200 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 201 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_STATUS); 202 if ((reg & QCOM_RND_PRNG_STATUS_DATA_AVAIL) == 0) 203 break; 204 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_DATA_OUT); 205 memcpy(((char *) buf) + rz, ®, sizeof(uint32_t)); 206 rz += sizeof(uint32_t); 207 } 208 209 if (rz == 0) 210 return (EAGAIN); 211 *sz = rz; 212 return (0); 213 } 214 215 static unsigned 216 qcom_rnd_read(void *buf, unsigned usz) 217 { 218 struct qcom_rnd_softc *sc; 219 size_t sz; 220 int error; 221 222 sc = g_qcom_rnd_softc; 223 if (sc == NULL) 224 return (0); 225 226 sz = usz; 227 error = qcom_rnd_harvest(sc, buf, &sz); 228 if (error != 0) 229 return (0); 230 231 return (sz); 232 } 233 234 static device_method_t qcom_rnd_methods[] = { 235 /* Device methods. */ 236 DEVMETHOD(device_probe, qcom_rnd_probe), 237 DEVMETHOD(device_attach, qcom_rnd_attach), 238 DEVMETHOD(device_detach, qcom_rnd_detach), 239 240 DEVMETHOD_END 241 }; 242 243 static driver_t qcom_rnd_driver = { 244 "qcom_rnd", 245 qcom_rnd_methods, 246 sizeof(struct qcom_rnd_softc) 247 }; 248 249 DRIVER_MODULE(qcom_rnd_random, simplebus, qcom_rnd_driver, 250 qcom_rnd_modevent, 0); 251 DRIVER_MODULE(qcom_rnd_random, ofwbus, qcom_rnd_driver, 252 qcom_rnd_modevent, 0); 253 MODULE_DEPEND(qcom_rnd_random, random_device, 1, 1, 1); 254 MODULE_VERSION(qcom_rnd_random, 1); 255