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/param.h> 31#include <sys/kernel.h> 32#include <sys/malloc.h> 33#include <sys/module.h> 34#include <sys/sglist.h> 35#include <sys/random.h> 36#include <sys/stdatomic.h> 37 38#include <machine/bus.h> 39#include <machine/resource.h> 40#include <sys/bus.h> 41 42#include <dev/fdt/fdt_common.h> 43#include <dev/ofw/ofw_bus.h> 44#include <dev/ofw/ofw_bus_subr.h> 45 46#include <dev/random/randomdev.h> 47#include <dev/random/random_harvestq.h> 48 49#include <dev/qcom_rnd/qcom_rnd_reg.h> 50 51struct qcom_rnd_softc { 52 device_t dev; 53 int reg_rid; 54 struct resource *reg; 55}; 56 57static int qcom_rnd_modevent(module_t, int, void *); 58 59static int qcom_rnd_probe(device_t); 60static int qcom_rnd_attach(device_t); 61static int qcom_rnd_detach(device_t); 62 63static int qcom_rnd_harvest(struct qcom_rnd_softc *, void *, size_t *); 64static unsigned qcom_rnd_read(void *, unsigned); 65 66static struct random_source random_qcom_rnd = { 67 .rs_ident = "Qualcomm Entropy Adapter", 68 .rs_source = RANDOM_PURE_QUALCOMM, 69 .rs_read = qcom_rnd_read, 70}; 71 72/* Kludge for API limitations of random(4). */ 73static _Atomic(struct qcom_rnd_softc *) g_qcom_rnd_softc; 74 75static int 76qcom_rnd_modevent(module_t mod, int type, void *unused) 77{ 78 int error; 79 80 switch (type) { 81 case MOD_LOAD: 82 case MOD_QUIESCE: 83 case MOD_UNLOAD: 84 case MOD_SHUTDOWN: 85 error = 0; 86 break; 87 default: 88 error = EOPNOTSUPP; 89 break; 90 } 91 92 return (error); 93} 94 95static int 96qcom_rnd_probe(device_t dev) 97{ 98 if (! ofw_bus_status_okay(dev)) { 99 return (ENXIO); 100 } 101 102 if (ofw_bus_is_compatible(dev, "qcom,prng") == 0) { 103 return (ENXIO); 104 } 105 106 return (0); 107} 108 109static int 110qcom_rnd_attach(device_t dev) 111{ 112 struct qcom_rnd_softc *sc, *exp; 113 uint32_t reg; 114 115 sc = device_get_softc(dev); 116 117 118 /* Found a compatible device! */ 119 120 sc->dev = dev; 121 122 exp = NULL; 123 if (!atomic_compare_exchange_strong_explicit(&g_qcom_rnd_softc, &exp, 124 sc, memory_order_release, memory_order_acquire)) { 125 return (ENXIO); 126 } 127 128 sc->reg_rid = 0; 129 sc->reg = bus_alloc_resource_anywhere(dev, SYS_RES_MEMORY, 130 &sc->reg_rid, 0x140, RF_ACTIVE); 131 if (sc->reg == NULL) { 132 device_printf(dev, "Couldn't allocate memory resource!\n"); 133 return (ENXIO); 134 } 135 136 device_set_desc(dev, "Qualcomm PRNG"); 137 138 /* 139 * Check to see whether the PRNG has already been setup or not. 140 */ 141 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 142 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 143 if (reg & QCOM_RND_PRNG_CONFIG_HW_ENABLE) { 144 device_printf(dev, "PRNG HW already enabled\n"); 145 } else { 146 /* 147 * Do PRNG setup and then enable it. 148 */ 149 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG); 150 reg &= QCOM_RND_PRNG_LFSR_CFG_MASK; 151 reg |= QCOM_RND_PRNG_LFSR_CFG_CLOCKS; 152 bus_write_4(sc->reg, QCOM_RND_PRNG_LFSR_CFG, reg); 153 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 154 155 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_CONFIG); 156 reg |= QCOM_RND_PRNG_CONFIG_HW_ENABLE; 157 bus_write_4(sc->reg, QCOM_RND_PRNG_CONFIG, reg); 158 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_WRITE); 159 } 160 161 random_source_register(&random_qcom_rnd); 162 return (0); 163 164} 165 166static int 167qcom_rnd_detach(device_t dev) 168{ 169 struct qcom_rnd_softc *sc; 170 171 sc = device_get_softc(dev); 172 KASSERT( 173 atomic_load_explicit(&g_qcom_rnd_softc, memory_order_acquire) == sc, 174 ("only one global instance at a time")); 175 176 random_source_deregister(&random_qcom_rnd); 177 if (sc->reg != NULL) { 178 bus_release_resource(sc->dev, SYS_RES_MEMORY, sc->reg_rid, sc->reg); 179 } 180 atomic_store_explicit(&g_qcom_rnd_softc, NULL, memory_order_release); 181 return (0); 182} 183 184static int 185qcom_rnd_harvest(struct qcom_rnd_softc *sc, void *buf, size_t *sz) 186{ 187 /* 188 * Add data to buf until we either run out of entropy or we 189 * fill the buffer. 190 * 191 * Note - be mindful of the provided buffer size; we're reading 192 * 4 bytes at a time but we only want to supply up to the max 193 * buffer size, so don't write past it! 194 */ 195 size_t rz = 0; 196 uint32_t reg; 197 198 while (rz < *sz) { 199 bus_barrier(sc->reg, 0, 0x120, BUS_SPACE_BARRIER_READ); 200 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_STATUS); 201 if ((reg & QCOM_RND_PRNG_STATUS_DATA_AVAIL) == 0) 202 break; 203 reg = bus_read_4(sc->reg, QCOM_RND_PRNG_DATA_OUT); 204 memcpy(((char *) buf) + rz, ®, sizeof(uint32_t)); 205 rz += sizeof(uint32_t); 206 } 207 208 if (rz == 0) 209 return (EAGAIN); 210 *sz = rz; 211 return (0); 212} 213 214static unsigned 215qcom_rnd_read(void *buf, unsigned usz) 216{ 217 struct qcom_rnd_softc *sc; 218 size_t sz; 219 int error; 220 221 sc = g_qcom_rnd_softc; 222 if (sc == NULL) 223 return (0); 224 225 sz = usz; 226 error = qcom_rnd_harvest(sc, buf, &sz); 227 if (error != 0) 228 return (0); 229 230 return (sz); 231} 232 233static device_method_t qcom_rnd_methods[] = { 234 /* Device methods. */ 235 DEVMETHOD(device_probe, qcom_rnd_probe), 236 DEVMETHOD(device_attach, qcom_rnd_attach), 237 DEVMETHOD(device_detach, qcom_rnd_detach), 238 239 DEVMETHOD_END 240}; 241 242static driver_t qcom_rnd_driver = { 243 "qcom_rnd", 244 qcom_rnd_methods, 245 sizeof(struct qcom_rnd_softc) 246}; 247 248DRIVER_MODULE(qcom_rnd_random, simplebus, qcom_rnd_driver, 249 qcom_rnd_modevent, 0); 250DRIVER_MODULE(qcom_rnd_random, ofwbus, qcom_rnd_driver, 251 qcom_rnd_modevent, 0); 252MODULE_DEPEND(qcom_rnd_random, random_device, 1, 1, 1); 253MODULE_VERSION(qcom_rnd_random, 1); 254