1 /* 2 * Exynos4210 Pseudo Random Number 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 "hw/sysbus.h" 22 #include "migration/vmstate.h" 23 #include "qapi/error.h" 24 #include "qemu/log.h" 25 #include "qemu/guest-random.h" 26 #include "qemu/module.h" 27 #include "qom/object.h" 28 29 #define DEBUG_EXYNOS_RNG 0 30 31 #define DPRINTF(fmt, ...) \ 32 do { \ 33 if (DEBUG_EXYNOS_RNG) { \ 34 printf("exynos4210_rng: " fmt, ## __VA_ARGS__); \ 35 } \ 36 } while (0) 37 38 #define TYPE_EXYNOS4210_RNG "exynos4210.rng" 39 OBJECT_DECLARE_SIMPLE_TYPE(Exynos4210RngState, EXYNOS4210_RNG) 40 41 /* 42 * Exynos4220, PRNG, only polling mode is supported. 43 */ 44 45 /* RNG_CONTROL_1 register bitfields, reset value: 0x0 */ 46 #define EXYNOS4210_RNG_CONTROL_1_PRNG 0x8 47 #define EXYNOS4210_RNG_CONTROL_1_START_INIT BIT(4) 48 /* RNG_STATUS register bitfields, reset value: 0x1 */ 49 #define EXYNOS4210_RNG_STATUS_PRNG_ERROR BIT(7) 50 #define EXYNOS4210_RNG_STATUS_PRNG_DONE BIT(5) 51 #define EXYNOS4210_RNG_STATUS_MSG_DONE BIT(4) 52 #define EXYNOS4210_RNG_STATUS_PARTIAL_DONE BIT(3) 53 #define EXYNOS4210_RNG_STATUS_PRNG_BUSY BIT(2) 54 #define EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE BIT(1) 55 #define EXYNOS4210_RNG_STATUS_BUFFER_READY BIT(0) 56 #define EXYNOS4210_RNG_STATUS_WRITE_MASK (EXYNOS4210_RNG_STATUS_PRNG_DONE \ 57 | EXYNOS4210_RNG_STATUS_MSG_DONE \ 58 | EXYNOS4210_RNG_STATUS_PARTIAL_DONE) 59 60 #define EXYNOS4210_RNG_CONTROL_1 0x0 61 #define EXYNOS4210_RNG_STATUS 0x10 62 #define EXYNOS4210_RNG_SEED_IN 0x140 63 #define EXYNOS4210_RNG_SEED_IN_OFFSET(n) (EXYNOS4210_RNG_SEED_IN + (n * 0x4)) 64 #define EXYNOS4210_RNG_PRNG 0x160 65 #define EXYNOS4210_RNG_PRNG_OFFSET(n) (EXYNOS4210_RNG_PRNG + (n * 0x4)) 66 67 #define EXYNOS4210_RNG_PRNG_NUM 5 68 69 #define EXYNOS4210_RNG_REGS_MEM_SIZE 0x200 70 71 struct Exynos4210RngState { 72 SysBusDevice parent_obj; 73 MemoryRegion iomem; 74 75 int32_t randr_value[EXYNOS4210_RNG_PRNG_NUM]; 76 /* bits from 0 to EXYNOS4210_RNG_PRNG_NUM if given seed register was set */ 77 uint32_t seed_set; 78 79 /* Register values */ 80 uint32_t reg_control; 81 uint32_t reg_status; 82 }; 83 84 static bool exynos4210_rng_seed_ready(const Exynos4210RngState *s) 85 { 86 uint32_t mask = MAKE_64BIT_MASK(0, EXYNOS4210_RNG_PRNG_NUM); 87 88 /* Return true if all the seed-set bits are set. */ 89 return (s->seed_set & mask) == mask; 90 } 91 92 static void exynos4210_rng_set_seed(Exynos4210RngState *s, unsigned int i, 93 uint64_t val) 94 { 95 /* 96 * We actually ignore the seed and always generate true random numbers. 97 * Theoretically this should not match the device as Exynos has 98 * a Pseudo Random Number Generator but testing shown that it always 99 * generates random numbers regardless of the seed value. 100 */ 101 s->seed_set |= BIT(i); 102 103 /* If all seeds were written, update the status to reflect it */ 104 if (exynos4210_rng_seed_ready(s)) { 105 s->reg_status |= EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; 106 } else { 107 s->reg_status &= ~EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE; 108 } 109 } 110 111 static void exynos4210_rng_run_engine(Exynos4210RngState *s) 112 { 113 Error *err = NULL; 114 115 /* Seed set? */ 116 if ((s->reg_status & EXYNOS4210_RNG_STATUS_SEED_SETTING_DONE) == 0) { 117 goto out; 118 } 119 120 /* PRNG engine chosen? */ 121 if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_PRNG) == 0) { 122 goto out; 123 } 124 125 /* PRNG engine started? */ 126 if ((s->reg_control & EXYNOS4210_RNG_CONTROL_1_START_INIT) == 0) { 127 goto out; 128 } 129 130 /* Get randoms */ 131 if (qemu_guest_getrandom(s->randr_value, sizeof(s->randr_value), &err)) { 132 error_report_err(err); 133 } else { 134 /* Notify that PRNG is ready */ 135 s->reg_status |= EXYNOS4210_RNG_STATUS_PRNG_DONE; 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 .valid.min_access_size = 4, 221 .valid.max_access_size = 4, 222 }; 223 224 static void exynos4210_rng_reset(DeviceState *dev) 225 { 226 Exynos4210RngState *s = EXYNOS4210_RNG(dev); 227 228 s->reg_control = 0; 229 s->reg_status = EXYNOS4210_RNG_STATUS_BUFFER_READY; 230 memset(s->randr_value, 0, sizeof(s->randr_value)); 231 s->seed_set = 0; 232 } 233 234 static void exynos4210_rng_init(Object *obj) 235 { 236 Exynos4210RngState *s = EXYNOS4210_RNG(obj); 237 SysBusDevice *dev = SYS_BUS_DEVICE(obj); 238 239 memory_region_init_io(&s->iomem, obj, &exynos4210_rng_ops, s, 240 TYPE_EXYNOS4210_RNG, EXYNOS4210_RNG_REGS_MEM_SIZE); 241 sysbus_init_mmio(dev, &s->iomem); 242 } 243 244 static const VMStateDescription exynos4210_rng_vmstate = { 245 .name = TYPE_EXYNOS4210_RNG, 246 .version_id = 1, 247 .minimum_version_id = 1, 248 .fields = (const VMStateField[]) { 249 VMSTATE_INT32_ARRAY(randr_value, Exynos4210RngState, 250 EXYNOS4210_RNG_PRNG_NUM), 251 VMSTATE_UINT32(seed_set, Exynos4210RngState), 252 VMSTATE_UINT32(reg_status, Exynos4210RngState), 253 VMSTATE_UINT32(reg_control, Exynos4210RngState), 254 VMSTATE_END_OF_LIST() 255 } 256 }; 257 258 static void exynos4210_rng_class_init(ObjectClass *klass, void *data) 259 { 260 DeviceClass *dc = DEVICE_CLASS(klass); 261 262 device_class_set_legacy_reset(dc, exynos4210_rng_reset); 263 dc->vmsd = &exynos4210_rng_vmstate; 264 } 265 266 static const TypeInfo exynos4210_rng_info = { 267 .name = TYPE_EXYNOS4210_RNG, 268 .parent = TYPE_SYS_BUS_DEVICE, 269 .instance_size = sizeof(Exynos4210RngState), 270 .instance_init = exynos4210_rng_init, 271 .class_init = exynos4210_rng_class_init, 272 }; 273 274 static void exynos4210_rng_register(void) 275 { 276 type_register_static(&exynos4210_rng_info); 277 } 278 279 type_init(exynos4210_rng_register) 280