1 /* 2 * Exynos4210 Pseudo Random Nubmer Generator Emulation 3 * 4 * Copyright (c) 2017 Krzysztof Kozlowski <krzk@kernel.org> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the 8 * Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * for more details. 15 * 16 * You should have received a copy of the GNU General Public License along 17 * with this program; if not, see <http://www.gnu.org/licenses/>. 18 */ 19 20 #include "qemu/osdep.h" 21 #include "crypto/random.h" 22 #include "hw/sysbus.h" 23 #include "qemu/log.h" 24 25 #define DEBUG_EXYNOS_RNG 0 26 27 #define DPRINTF(fmt, ...) \ 28 do { \ 29 if (DEBUG_EXYNOS_RNG) { \ 30 printf("exynos4210_rng: " fmt, ## __VA_ARGS__); \ 31 } \ 32 } while (0) 33 34 #define TYPE_EXYNOS4210_RNG "exynos4210.rng" 35 #define EXYNOS4210_RNG(obj) \ 36 OBJECT_CHECK(Exynos4210RngState, (obj), TYPE_EXYNOS4210_RNG) 37 38 /* 39 * Exynos4220, PRNG, only polling mode is supported. 40 */ 41 42 /* RNG_CONTROL_1 register bitfields, reset value: 0x0 */ 43 #define EXYNOS4210_RNG_CONTROL_1_PRNG 0x8 44 #define EXYNOS4210_RNG_CONTROL_1_START_INIT BIT(4) 45 /* RNG_STATUS register bitfields, reset value: 0x1 */ 46 #define EXYNOS4210_RNG_STATUS_PRNG_ERROR BIT(7) 47 #define EXYNOS4210_RNG_STATUS_PRNG_DONE BIT(5) 48 #define EXYNOS4210_RNG_STATUS_MSG_DONE BIT(4) 49 #define EXYNOS4210_RNG_STATUS_PARTIAL_DONE BIT(3) 50 #define EXYNOS4210_RNG_STATUS_PRNG_BUSY BIT(2) 51 #define EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE BIT(1) 52 #define EXYNOS4210_RNG_STATUS_BUFFER_READY BIT(0) 53 #define EXYNOS4210_RNG_STATUS_WRITE_MASK (EXYNOS4210_RNG_STATUS_PRNG_DONE \ 54 | EXYNOS4210_RNG_STATUS_MSG_DONE \ 55 | EXYNOS4210_RNG_STATUS_PARTIAL_DONE) 56 57 #define EXYNOS4210_RNG_CONTROL_1 0x0 58 #define EXYNOS4210_RNG_STATUS 0x10 59 #define EXYNOS4210_RNG_SEED_IN 0x140 60 #define EXYNOS4210_RNG_SEED_IN_OFFSET(n) (EXYNOS4210_RNG_SEED_IN + (n * 0x4)) 61 #define EXYNOS4210_RNG_PRNG 0x160 62 #define EXYNOS4210_RNG_PRNG_OFFSET(n) (EXYNOS4210_RNG_PRNG + (n * 0x4)) 63 64 #define EXYNOS4210_RNG_PRNG_NUM 5 65 66 #define EXYNOS4210_RNG_REGS_MEM_SIZE 0x200 67 68 typedef struct Exynos4210RngState { 69 SysBusDevice parent_obj; 70 MemoryRegion iomem; 71 72 int32_t randr_value[EXYNOS4210_RNG_PRNG_NUM]; 73 /* bits from 0 to EXYNOS4210_RNG_PRNG_NUM if given seed register was set */ 74 uint32_t seed_set; 75 76 /* Register values */ 77 uint32_t reg_control; 78 uint32_t reg_status; 79 } Exynos4210RngState; 80 81 static bool exynos4210_rng_seed_ready(const Exynos4210RngState *s) 82 { 83 uint32_t mask = MAKE_64BIT_MASK(0, EXYNOS4210_RNG_PRNG_NUM); 84 85 /* Return true if all the seed-set bits are set. */ 86 return (s->seed_set & mask) == mask; 87 } 88 89 static void exynos4210_rng_set_seed(Exynos4210RngState *s, unsigned int i, 90 uint64_t val) 91 { 92 /* 93 * We actually ignore the seed and always generate true random numbers. 94 * Theoretically this should not match the device as Exynos has 95 * a Pseudo Random Number Generator but testing shown that it always 96 * generates random numbers regardless of the seed value. 97 */ 98 s->seed_set |= BIT(i); 99 100 /* If all seeds were written, update the status to reflect it */ 101 if (exynos4210_rng_seed_ready(s)) { 102 s->reg_status |= EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; 103 } else { 104 s->reg_status &= ~EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; 105 } 106 } 107 108 static void exynos4210_rng_run_engine(Exynos4210RngState *s) 109 { 110 Error *err = NULL; 111 int ret; 112 113 /* Seed set? */ 114 if ((s->reg_status & EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE) == 0) { 115 goto out; 116 } 117 118 /* PRNG engine chosen? */ 119 if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_PRNG) == 0) { 120 goto out; 121 } 122 123 /* PRNG engine started? */ 124 if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_START_INIT) == 0) { 125 goto out; 126 } 127 128 /* Get randoms */ 129 ret = qcrypto_random_bytes((uint8_t *)s->randr_value, 130 sizeof(s->randr_value), &err); 131 if (!ret) { 132 /* Notify that PRNG is ready */ 133 s->reg_status |= EXYNOS4210_RNG_STATUS_PRNG_DONE; 134 } else { 135 error_report_err(err); 136 } 137 138 out: 139 /* Always clear start engine bit */ 140 s->reg_control &= ~EXYNOS4210_RNG_CONTROL_1_START_INIT; 141 } 142 143 static uint64_t exynos4210_rng_read(void *opaque, hwaddr offset, 144 unsigned size) 145 { 146 Exynos4210RngState *s = (Exynos4210RngState *)opaque; 147 uint32_t val = 0; 148 149 assert(size == 4); 150 151 switch (offset) { 152 case EXYNOS4210_RNG_CONTROL_1: 153 val = s->reg_control; 154 break; 155 156 case EXYNOS4210_RNG_STATUS: 157 val = s->reg_status; 158 break; 159 160 case EXYNOS4210_RNG_PRNG_OFFSET(0): 161 case EXYNOS4210_RNG_PRNG_OFFSET(1): 162 case EXYNOS4210_RNG_PRNG_OFFSET(2): 163 case EXYNOS4210_RNG_PRNG_OFFSET(3): 164 case EXYNOS4210_RNG_PRNG_OFFSET(4): 165 val = s->randr_value[(offset - EXYNOS4210_RNG_PRNG_OFFSET(0)) / 4]; 166 DPRINTF("returning random @0x%" HWADDR_PRIx ": 0x%" PRIx32 "\n", 167 offset, val); 168 break; 169 170 default: 171 qemu_log_mask(LOG_GUEST_ERROR, 172 "%s: bad read offset 0x%" HWADDR_PRIx "\n", 173 __func__, offset); 174 } 175 176 return val; 177 } 178 179 static void exynos4210_rng_write(void *opaque, hwaddr offset, 180 uint64_t val, unsigned size) 181 { 182 Exynos4210RngState *s = (Exynos4210RngState *)opaque; 183 184 assert(size == 4); 185 186 switch (offset) { 187 case EXYNOS4210_RNG_CONTROL_1: 188 DPRINTF("RNG_CONTROL_1 = 0x%" PRIx64 "\n", val); 189 s->reg_control = val; 190 exynos4210_rng_run_engine(s); 191 break; 192 193 case EXYNOS4210_RNG_STATUS: 194 /* For clearing status fields */ 195 s->reg_status &= ~EXYNOS4210_RNG_STATUS_WRITE_MASK; 196 s->reg_status |= val & EXYNOS4210_RNG_STATUS_WRITE_MASK; 197 break; 198 199 case EXYNOS4210_RNG_SEED_IN_OFFSET(0): 200 case EXYNOS4210_RNG_SEED_IN_OFFSET(1): 201 case EXYNOS4210_RNG_SEED_IN_OFFSET(2): 202 case EXYNOS4210_RNG_SEED_IN_OFFSET(3): 203 case EXYNOS4210_RNG_SEED_IN_OFFSET(4): 204 exynos4210_rng_set_seed(s, 205 (offset - EXYNOS4210_RNG_SEED_IN_OFFSET(0)) / 4, 206 val); 207 break; 208 209 default: 210 qemu_log_mask(LOG_GUEST_ERROR, 211 "%s: bad write offset 0x%" HWADDR_PRIx "\n", 212 __func__, offset); 213 } 214 } 215 216 static const MemoryRegionOps exynos4210_rng_ops = { 217 .read = exynos4210_rng_read, 218 .write = exynos4210_rng_write, 219 .endianness = DEVICE_NATIVE_ENDIAN, 220 }; 221 222 static void exynos4210_rng_reset(DeviceState *dev) 223 { 224 Exynos4210RngState *s = EXYNOS4210_RNG(dev); 225 226 s->reg_control = 0; 227 s->reg_status = EXYNOS4210_RNG_STATUS_BUFFER_READY; 228 memset(s->randr_value, 0, sizeof(s->randr_value)); 229 s->seed_set = 0; 230 } 231 232 static void exynos4210_rng_init(Object *obj) 233 { 234 Exynos4210RngState *s = EXYNOS4210_RNG(obj); 235 SysBusDevice *dev = SYS_BUS_DEVICE(obj); 236 237 memory_region_init_io(&s->iomem, obj, &exynos4210_rng_ops, s, 238 TYPE_EXYNOS4210_RNG, EXYNOS4210_RNG_REGS_MEM_SIZE); 239 sysbus_init_mmio(dev, &s->iomem); 240 } 241 242 static const VMStateDescription exynos4210_rng_vmstate = { 243 .name = TYPE_EXYNOS4210_RNG, 244 .version_id = 1, 245 .minimum_version_id = 1, 246 .fields = (VMStateField[]) { 247 VMSTATE_INT32_ARRAY(randr_value, Exynos4210RngState, 248 EXYNOS4210_RNG_PRNG_NUM), 249 VMSTATE_UINT32(seed_set, Exynos4210RngState), 250 VMSTATE_UINT32(reg_status, Exynos4210RngState), 251 VMSTATE_UINT32(reg_control, Exynos4210RngState), 252 VMSTATE_END_OF_LIST() 253 } 254 }; 255 256 static void exynos4210_rng_class_init(ObjectClass *klass, void *data) 257 { 258 DeviceClass *dc = DEVICE_CLASS(klass); 259 260 dc->reset = exynos4210_rng_reset; 261 dc->vmsd = &exynos4210_rng_vmstate; 262 } 263 264 static const TypeInfo exynos4210_rng_info = { 265 .name = TYPE_EXYNOS4210_RNG, 266 .parent = TYPE_SYS_BUS_DEVICE, 267 .instance_size = sizeof(Exynos4210RngState), 268 .instance_init = exynos4210_rng_init, 269 .class_init = exynos4210_rng_class_init, 270 }; 271 272 static void exynos4210_rng_register(void) 273 { 274 type_register_static(&exynos4210_rng_info); 275 } 276 277 type_init(exynos4210_rng_register) 278