hw/misc/nrf51_rng.c

   1 /*
   2  * nRF51 Random Number Generator
   3  *
   4  * Reference Manual: http://infocenter.nordicsemi.com/pdf/nRF51_RM_v3.0.1.pdf
   5  *
   6  * Copyright 2018 Steffen Görtz <contrib@steffen-goertz.de>
   7  *
   8  * This code is licensed under the GPL version 2 or later.  See
   9  * the COPYING file in the top-level directory.
  10  */
  11
  12 #include "qemu/osdep.h"
  13 #include "qemu/log.h"
  14 #include "qemu/module.h"
  15 #include "qapi/error.h"
  16 #include "hw/arm/nrf51.h"
  17 #include "hw/irq.h"
  18 #include "hw/misc/nrf51_rng.h"
  19 #include "hw/qdev-properties.h"
  20 #include "migration/vmstate.h"
  21 #include "qemu/guest-random.h"
  22
  23 static void update_irq(NRF51RNGState *s)
  24 {
  25     bool irq = s->interrupt_enabled && s->event_valrdy;
  26     qemu_set_irq(s->irq, irq);
  27 }
  28
  29 static uint64_t rng_read(void *opaque, hwaddr offset, unsigned int size)
  30 {
  31     NRF51RNGState *s = NRF51_RNG(opaque);
  32     uint64_t r = 0;
  33
  34     switch (offset) {
  35     case NRF51_RNG_EVENT_VALRDY:
  36         r = s->event_valrdy;
  37         break;
  38     case NRF51_RNG_REG_SHORTS:
  39         r = s->shortcut_stop_on_valrdy;
  40         break;
  41     case NRF51_RNG_REG_INTEN:
  42     case NRF51_RNG_REG_INTENSET:
  43     case NRF51_RNG_REG_INTENCLR:
  44         r = s->interrupt_enabled;
  45         break;
  46     case NRF51_RNG_REG_CONFIG:
  47         r = s->filter_enabled;
  48         break;
  49     case NRF51_RNG_REG_VALUE:
  50         r = s->value;
  51         break;
  52
  53     default:
  54         qemu_log_mask(LOG_GUEST_ERROR,
  55                       "%s: bad read offset 0x%" HWADDR_PRIx "\n",
  56                       __func__, offset);
  57     }
  58
  59     return r;
  60 }
  61
  62 static int64_t calc_next_timeout(NRF51RNGState *s)
  63 {
  64     int64_t timeout = qemu_clock_get_us(QEMU_CLOCK_VIRTUAL);
  65     if (s->filter_enabled) {
  66         timeout += s->period_filtered_us;
  67     } else {
  68         timeout += s->period_unfiltered_us;
  69     }
  70
  71     return timeout;
  72 }
  73
  74
  75 static void rng_update_timer(NRF51RNGState *s)
  76 {
  77     if (s->active) {
  78         timer_mod(&s->timer, calc_next_timeout(s));
  79     } else {
  80         timer_del(&s->timer);
  81     }
  82 }
  83
  84
  85 static void rng_write(void *opaque, hwaddr offset,
  86                        uint64_t value, unsigned int size)
  87 {
  88     NRF51RNGState *s = NRF51_RNG(opaque);
  89
  90     switch (offset) {
  91     case NRF51_RNG_TASK_START:
  92         if (value == NRF51_TRIGGER_TASK) {
  93             s->active = 1;
  94             rng_update_timer(s);
  95         }
  96         break;
  97     case NRF51_RNG_TASK_STOP:
  98         if (value == NRF51_TRIGGER_TASK) {
  99             s->active = 0;
 100             rng_update_timer(s);
 101         }
 102         break;
 103     case NRF51_RNG_EVENT_VALRDY:
 104         if (value == NRF51_EVENT_CLEAR) {
 105             s->event_valrdy = 0;
 106         }
 107         break;
 108     case NRF51_RNG_REG_SHORTS:
 109         s->shortcut_stop_on_valrdy =
 110                 (value & BIT_MASK(NRF51_RNG_REG_SHORTS_VALRDY_STOP)) ? 1 : 0;
 111         break;
 112     case NRF51_RNG_REG_INTEN:
 113         s->interrupt_enabled =
 114                 (value & BIT_MASK(NRF51_RNG_REG_INTEN_VALRDY)) ? 1 : 0;
 115         break;
 116     case NRF51_RNG_REG_INTENSET:
 117         if (value & BIT_MASK(NRF51_RNG_REG_INTEN_VALRDY)) {
 118             s->interrupt_enabled = 1;
 119         }
 120         break;
 121     case NRF51_RNG_REG_INTENCLR:
 122         if (value & BIT_MASK(NRF51_RNG_REG_INTEN_VALRDY)) {
 123             s->interrupt_enabled = 0;
 124         }
 125         break;
 126     case NRF51_RNG_REG_CONFIG:
 127         s->filter_enabled =
 128                       (value & BIT_MASK(NRF51_RNG_REG_CONFIG_DECEN)) ? 1 : 0;
 129         break;
 130
 131     default:
 132         qemu_log_mask(LOG_GUEST_ERROR,
 133                       "%s: bad write offset 0x%" HWADDR_PRIx "\n",
 134                       __func__, offset);
 135     }
 136
 137     update_irq(s);
 138 }
 139
 140 static const MemoryRegionOps rng_ops = {
 141     .read =  rng_read,
 142     .write = rng_write,
 143     .endianness = DEVICE_LITTLE_ENDIAN,
 144     .impl.min_access_size = 4,
 145     .impl.max_access_size = 4
 146 };
 147
 148 static void nrf51_rng_timer_expire(void *opaque)
 149 {
 150     NRF51RNGState *s = NRF51_RNG(opaque);
 151
 152     qemu_guest_getrandom_nofail(&s->value, 1);
 153
 154     s->event_valrdy = 1;
 155     qemu_set_irq(s->eep_valrdy, 1);
 156
 157     if (s->shortcut_stop_on_valrdy) {
 158         s->active = 0;
 159     }
 160
 161     rng_update_timer(s);
 162     update_irq(s);
 163 }
 164
 165 static void nrf51_rng_tep_start(void *opaque, int n, int level)
 166 {
 167     NRF51RNGState *s = NRF51_RNG(opaque);
 168
 169     if (level) {
 170         s->active = 1;
 171         rng_update_timer(s);
 172     }
 173 }
 174
 175 static void nrf51_rng_tep_stop(void *opaque, int n, int level)
 176 {
 177     NRF51RNGState *s = NRF51_RNG(opaque);
 178
 179     if (level) {
 180         s->active = 0;
 181         rng_update_timer(s);
 182     }
 183 }
 184
 185
 186 static void nrf51_rng_init(Object *obj)
 187 {
 188     NRF51RNGState *s = NRF51_RNG(obj);
 189     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 190
 191     memory_region_init_io(&s->mmio, obj, &rng_ops, s,
 192             TYPE_NRF51_RNG, NRF51_RNG_SIZE);
 193     sysbus_init_mmio(sbd, &s->mmio);
 194
 195     timer_init_us(&s->timer, QEMU_CLOCK_VIRTUAL, nrf51_rng_timer_expire, s);
 196
 197     sysbus_init_irq(sbd, &s->irq);
 198
 199     /* Tasks */
 200     qdev_init_gpio_in_named(DEVICE(s), nrf51_rng_tep_start, "tep_start", 1);
 201     qdev_init_gpio_in_named(DEVICE(s), nrf51_rng_tep_stop, "tep_stop", 1);
 202
 203     /* Events */
 204     qdev_init_gpio_out_named(DEVICE(s), &s->eep_valrdy, "eep_valrdy", 1);
 205 }
 206
 207 static void nrf51_rng_reset(DeviceState *dev)
 208 {
 209     NRF51RNGState *s = NRF51_RNG(dev);
 210
 211     s->value = 0;
 212     s->active = 0;
 213     s->event_valrdy = 0;
 214     s->shortcut_stop_on_valrdy = 0;
 215     s->interrupt_enabled = 0;
 216     s->filter_enabled = 0;
 217
 218     rng_update_timer(s);
 219 }
 220
 221
 222 static Property nrf51_rng_properties[] = {
 223     DEFINE_PROP_UINT16("period_unfiltered_us", NRF51RNGState,
 224             period_unfiltered_us, 167),
 225     DEFINE_PROP_UINT16("period_filtered_us", NRF51RNGState,
 226             period_filtered_us, 660),
 227     DEFINE_PROP_END_OF_LIST(),
 228 };
 229
 230 static const VMStateDescription vmstate_rng = {
 231     .name = "nrf51_soc.rng",
 232     .version_id = 1,
 233     .minimum_version_id = 1,
 234     .fields = (VMStateField[]) {
 235         VMSTATE_UINT32(active, NRF51RNGState),
 236         VMSTATE_UINT32(event_valrdy, NRF51RNGState),
 237         VMSTATE_UINT32(shortcut_stop_on_valrdy, NRF51RNGState),
 238         VMSTATE_UINT32(interrupt_enabled, NRF51RNGState),
 239         VMSTATE_UINT32(filter_enabled, NRF51RNGState),
 240         VMSTATE_END_OF_LIST()
 241     }
 242 };
 243
 244 static void nrf51_rng_class_init(ObjectClass *klass, void *data)
 245 {
 246     DeviceClass *dc = DEVICE_CLASS(klass);
 247
 248     device_class_set_props(dc, nrf51_rng_properties);
 249     dc->vmsd = &vmstate_rng;
 250     dc->reset = nrf51_rng_reset;
 251 }
 252
 253 static const TypeInfo nrf51_rng_info = {
 254     .name = TYPE_NRF51_RNG,
 255     .parent = TYPE_SYS_BUS_DEVICE,
 256     .instance_size = sizeof(NRF51RNGState),
 257     .instance_init = nrf51_rng_init,
 258     .class_init = nrf51_rng_class_init
 259 };
 260
 261 static void nrf51_rng_register_types(void)
 262 {
 263     type_register_static(&nrf51_rng_info);
 264 }
 265
 266 type_init(nrf51_rng_register_types)