hw/misc/mos6522.c

   1 /*
   2  * QEMU MOS6522 VIA emulation
   3  *
   4  * Copyright (c) 2004-2007 Fabrice Bellard
   5  * Copyright (c) 2007 Jocelyn Mayer
   6  * Copyright (c) 2018 Mark Cave-Ayland
   7  *
   8  * Permission is hereby granted, free of charge, to any person obtaining a copy
   9  * of this software and associated documentation files (the "Software"), to deal
  10  * in the Software without restriction, including without limitation the rights
  11  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  12  * copies of the Software, and to permit persons to whom the Software is
  13  * furnished to do so, subject to the following conditions:
  14  *
  15  * The above copyright notice and this permission notice shall be included in
  16  * all copies or substantial portions of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  21  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  22  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  23  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  24  * THE SOFTWARE.
  25  */
  26
  27 #include "qemu/osdep.h"
  28 #include "hw/input/adb.h"
  29 #include "hw/irq.h"
  30 #include "hw/misc/mos6522.h"
  31 #include "hw/qdev-properties.h"
  32 #include "migration/vmstate.h"
  33 #include "qemu/timer.h"
  34 #include "qemu/cutils.h"
  35 #include "qemu/log.h"
  36 #include "qemu/module.h"
  37 #include "trace.h"
  38
  39 /* XXX: implement all timer modes */
  40
  41 static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
  42                                   int64_t current_time);
  43 static void mos6522_timer2_update(MOS6522State *s, MOS6522Timer *ti,
  44                                   int64_t current_time);
  45
  46 static void mos6522_update_irq(MOS6522State *s)
  47 {
  48     if (s->ifr & s->ier) {
  49         qemu_irq_raise(s->irq);
  50     } else {
  51         qemu_irq_lower(s->irq);
  52     }
  53 }
  54
  55 static uint64_t get_counter_value(MOS6522State *s, MOS6522Timer *ti)
  56 {
  57     MOS6522DeviceClass *mdc = MOS6522_DEVICE_GET_CLASS(s);
  58
  59     if (ti->index == 0) {
  60         return mdc->get_timer1_counter_value(s, ti);
  61     } else {
  62         return mdc->get_timer2_counter_value(s, ti);
  63     }
  64 }
  65
  66 static uint64_t get_load_time(MOS6522State *s, MOS6522Timer *ti)
  67 {
  68     MOS6522DeviceClass *mdc = MOS6522_DEVICE_GET_CLASS(s);
  69
  70     if (ti->index == 0) {
  71         return mdc->get_timer1_load_time(s, ti);
  72     } else {
  73         return mdc->get_timer2_load_time(s, ti);
  74     }
  75 }
  76
  77 static unsigned int get_counter(MOS6522State *s, MOS6522Timer *ti)
  78 {
  79     int64_t d;
  80     unsigned int counter;
  81
  82     d = get_counter_value(s, ti);
  83
  84     if (ti->index == 0) {
  85         /* the timer goes down from latch to -1 (period of latch + 2) */
  86         if (d <= (ti->counter_value + 1)) {
  87             counter = (ti->counter_value - d) & 0xffff;
  88         } else {
  89             counter = (d - (ti->counter_value + 1)) % (ti->latch + 2);
  90             counter = (ti->latch - counter) & 0xffff;
  91         }
  92     } else {
  93         counter = (ti->counter_value - d) & 0xffff;
  94     }
  95     return counter;
  96 }
  97
  98 static void set_counter(MOS6522State *s, MOS6522Timer *ti, unsigned int val)
  99 {
 100     trace_mos6522_set_counter(1 + ti->index, val);
 101     ti->load_time = get_load_time(s, ti);
 102     ti->counter_value = val;
 103     if (ti->index == 0) {
 104         mos6522_timer1_update(s, ti, ti->load_time);
 105     } else {
 106         mos6522_timer2_update(s, ti, ti->load_time);
 107     }
 108 }
 109
 110 static int64_t get_next_irq_time(MOS6522State *s, MOS6522Timer *ti,
 111                                  int64_t current_time)
 112 {
 113     int64_t d, next_time;
 114     unsigned int counter;
 115
 116     if (ti->frequency == 0) {
 117         return INT64_MAX;
 118     }
 119
 120     /* current counter value */
 121     d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ti->load_time,
 122                  ti->frequency, NANOSECONDS_PER_SECOND);
 123
 124     /* the timer goes down from latch to -1 (period of latch + 2) */
 125     if (d <= (ti->counter_value + 1)) {
 126         counter = (ti->counter_value - d) & 0xffff;
 127     } else {
 128         counter = (d - (ti->counter_value + 1)) % (ti->latch + 2);
 129         counter = (ti->latch - counter) & 0xffff;
 130     }
 131
 132     /* Note: we consider the irq is raised on 0 */
 133     if (counter == 0xffff) {
 134         next_time = d + ti->latch + 1;
 135     } else if (counter == 0) {
 136         next_time = d + ti->latch + 2;
 137     } else {
 138         next_time = d + counter;
 139     }
 140     trace_mos6522_get_next_irq_time(ti->latch, d, next_time - d);
 141     next_time = muldiv64(next_time, NANOSECONDS_PER_SECOND, ti->frequency) +
 142                          ti->load_time;
 143
 144     if (next_time <= current_time) {
 145         next_time = current_time + 1;
 146     }
 147     return next_time;
 148 }
 149
 150 static void mos6522_timer1_update(MOS6522State *s, MOS6522Timer *ti,
 151                                  int64_t current_time)
 152 {
 153     if (!ti->timer) {
 154         return;
 155     }
 156     ti->next_irq_time = get_next_irq_time(s, ti, current_time);
 157     if ((s->ier & T1_INT) == 0 || (s->acr & T1MODE) != T1MODE_CONT) {
 158         timer_del(ti->timer);
 159     } else {
 160         timer_mod(ti->timer, ti->next_irq_time);
 161     }
 162 }
 163
 164 static void mos6522_timer2_update(MOS6522State *s, MOS6522Timer *ti,
 165                                  int64_t current_time)
 166 {
 167     if (!ti->timer) {
 168         return;
 169     }
 170     ti->next_irq_time = get_next_irq_time(s, ti, current_time);
 171     if ((s->ier & T2_INT) == 0) {
 172         timer_del(ti->timer);
 173     } else {
 174         timer_mod(ti->timer, ti->next_irq_time);
 175     }
 176 }
 177
 178 static void mos6522_timer1(void *opaque)
 179 {
 180     MOS6522State *s = opaque;
 181     MOS6522Timer *ti = &s->timers[0];
 182
 183     mos6522_timer1_update(s, ti, ti->next_irq_time);
 184     s->ifr |= T1_INT;
 185     mos6522_update_irq(s);
 186 }
 187
 188 static void mos6522_timer2(void *opaque)
 189 {
 190     MOS6522State *s = opaque;
 191     MOS6522Timer *ti = &s->timers[1];
 192
 193     mos6522_timer2_update(s, ti, ti->next_irq_time);
 194     s->ifr |= T2_INT;
 195     mos6522_update_irq(s);
 196 }
 197
 198 static void mos6522_set_sr_int(MOS6522State *s)
 199 {
 200     trace_mos6522_set_sr_int();
 201     s->ifr |= SR_INT;
 202     mos6522_update_irq(s);
 203 }
 204
 205 static uint64_t mos6522_get_counter_value(MOS6522State *s, MOS6522Timer *ti)
 206 {
 207     return muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - ti->load_time,
 208                     ti->frequency, NANOSECONDS_PER_SECOND);
 209 }
 210
 211 static uint64_t mos6522_get_load_time(MOS6522State *s, MOS6522Timer *ti)
 212 {
 213     uint64_t load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 214
 215     return load_time;
 216 }
 217
 218 static void mos6522_portA_write(MOS6522State *s)
 219 {
 220     qemu_log_mask(LOG_UNIMP, "portA_write unimplemented\n");
 221 }
 222
 223 static void mos6522_portB_write(MOS6522State *s)
 224 {
 225     qemu_log_mask(LOG_UNIMP, "portB_write unimplemented\n");
 226 }
 227
 228 uint64_t mos6522_read(void *opaque, hwaddr addr, unsigned size)
 229 {
 230     MOS6522State *s = opaque;
 231     uint32_t val;
 232     int64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 233
 234     if (now >= s->timers[0].next_irq_time) {
 235         mos6522_timer1_update(s, &s->timers[0], now);
 236         s->ifr |= T1_INT;
 237     }
 238     if (now >= s->timers[1].next_irq_time) {
 239         mos6522_timer2_update(s, &s->timers[1], now);
 240         s->ifr |= T2_INT;
 241     }
 242     switch (addr) {
 243     case VIA_REG_B:
 244         val = s->b;
 245         break;
 246     case VIA_REG_A:
 247        qemu_log_mask(LOG_UNIMP, "Read access to register A with handshake");
 248        /* fall through */
 249     case VIA_REG_ANH:
 250         val = s->a;
 251         break;
 252     case VIA_REG_DIRB:
 253         val = s->dirb;
 254         break;
 255     case VIA_REG_DIRA:
 256         val = s->dira;
 257         break;
 258     case VIA_REG_T1CL:
 259         val = get_counter(s, &s->timers[0]) & 0xff;
 260         s->ifr &= ~T1_INT;
 261         mos6522_update_irq(s);
 262         break;
 263     case VIA_REG_T1CH:
 264         val = get_counter(s, &s->timers[0]) >> 8;
 265         mos6522_update_irq(s);
 266         break;
 267     case VIA_REG_T1LL:
 268         val = s->timers[0].latch & 0xff;
 269         break;
 270     case VIA_REG_T1LH:
 271         /* XXX: check this */
 272         val = (s->timers[0].latch >> 8) & 0xff;
 273         break;
 274     case VIA_REG_T2CL:
 275         val = get_counter(s, &s->timers[1]) & 0xff;
 276         s->ifr &= ~T2_INT;
 277         mos6522_update_irq(s);
 278         break;
 279     case VIA_REG_T2CH:
 280         val = get_counter(s, &s->timers[1]) >> 8;
 281         break;
 282     case VIA_REG_SR:
 283         val = s->sr;
 284         s->ifr &= ~SR_INT;
 285         mos6522_update_irq(s);
 286         break;
 287     case VIA_REG_ACR:
 288         val = s->acr;
 289         break;
 290     case VIA_REG_PCR:
 291         val = s->pcr;
 292         break;
 293     case VIA_REG_IFR:
 294         val = s->ifr;
 295         if (s->ifr & s->ier) {
 296             val |= 0x80;
 297         }
 298         break;
 299     case VIA_REG_IER:
 300         val = s->ier | 0x80;
 301         break;
 302     default:
 303         g_assert_not_reached();
 304     }
 305
 306     if (addr != VIA_REG_IFR || val != 0) {
 307         trace_mos6522_read(addr, val);
 308     }
 309
 310     return val;
 311 }
 312
 313 void mos6522_write(void *opaque, hwaddr addr, uint64_t val, unsigned size)
 314 {
 315     MOS6522State *s = opaque;
 316     MOS6522DeviceClass *mdc = MOS6522_DEVICE_GET_CLASS(s);
 317
 318     trace_mos6522_write(addr, val);
 319
 320     switch (addr) {
 321     case VIA_REG_B:
 322         s->b = (s->b & ~s->dirb) | (val & s->dirb);
 323         mdc->portB_write(s);
 324         break;
 325     case VIA_REG_A:
 326        qemu_log_mask(LOG_UNIMP, "Write access to register A with handshake");
 327        /* fall through */
 328     case VIA_REG_ANH:
 329         s->a = (s->a & ~s->dira) | (val & s->dira);
 330         mdc->portA_write(s);
 331         break;
 332     case VIA_REG_DIRB:
 333         s->dirb = val;
 334         break;
 335     case VIA_REG_DIRA:
 336         s->dira = val;
 337         break;
 338     case VIA_REG_T1CL:
 339         s->timers[0].latch = (s->timers[0].latch & 0xff00) | val;
 340         mos6522_timer1_update(s, &s->timers[0],
 341                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 342         break;
 343     case VIA_REG_T1CH:
 344         s->timers[0].latch = (s->timers[0].latch & 0xff) | (val << 8);
 345         s->ifr &= ~T1_INT;
 346         set_counter(s, &s->timers[0], s->timers[0].latch);
 347         break;
 348     case VIA_REG_T1LL:
 349         s->timers[0].latch = (s->timers[0].latch & 0xff00) | val;
 350         mos6522_timer1_update(s, &s->timers[0],
 351                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 352         break;
 353     case VIA_REG_T1LH:
 354         s->timers[0].latch = (s->timers[0].latch & 0xff) | (val << 8);
 355         s->ifr &= ~T1_INT;
 356         mos6522_timer1_update(s, &s->timers[0],
 357                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 358         break;
 359     case VIA_REG_T2CL:
 360         s->timers[1].latch = (s->timers[1].latch & 0xff00) | val;
 361         break;
 362     case VIA_REG_T2CH:
 363         /* To ensure T2 generates an interrupt on zero crossing with the
 364            common timer code, write the value directly from the latch to
 365            the counter */
 366         s->timers[1].latch = (s->timers[1].latch & 0xff) | (val << 8);
 367         s->ifr &= ~T2_INT;
 368         set_counter(s, &s->timers[1], s->timers[1].latch);
 369         break;
 370     case VIA_REG_SR:
 371         s->sr = val;
 372         break;
 373     case VIA_REG_ACR:
 374         s->acr = val;
 375         mos6522_timer1_update(s, &s->timers[0],
 376                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 377         break;
 378     case VIA_REG_PCR:
 379         s->pcr = val;
 380         break;
 381     case VIA_REG_IFR:
 382         /* reset bits */
 383         s->ifr &= ~val;
 384         mos6522_update_irq(s);
 385         break;
 386     case VIA_REG_IER:
 387         if (val & IER_SET) {
 388             /* set bits */
 389             s->ier |= val & 0x7f;
 390         } else {
 391             /* reset bits */
 392             s->ier &= ~val;
 393         }
 394         mos6522_update_irq(s);
 395         /* if IER is modified starts needed timers */
 396         mos6522_timer1_update(s, &s->timers[0],
 397                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 398         mos6522_timer2_update(s, &s->timers[1],
 399                               qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 400         break;
 401     default:
 402         g_assert_not_reached();
 403     }
 404 }
 405
 406 static const MemoryRegionOps mos6522_ops = {
 407     .read = mos6522_read,
 408     .write = mos6522_write,
 409     .endianness = DEVICE_NATIVE_ENDIAN,
 410     .valid = {
 411         .min_access_size = 1,
 412         .max_access_size = 1,
 413     },
 414 };
 415
 416 static const VMStateDescription vmstate_mos6522_timer = {
 417     .name = "mos6522_timer",
 418     .version_id = 0,
 419     .minimum_version_id = 0,
 420     .fields = (VMStateField[]) {
 421         VMSTATE_UINT16(latch, MOS6522Timer),
 422         VMSTATE_UINT16(counter_value, MOS6522Timer),
 423         VMSTATE_INT64(load_time, MOS6522Timer),
 424         VMSTATE_INT64(next_irq_time, MOS6522Timer),
 425         VMSTATE_TIMER_PTR(timer, MOS6522Timer),
 426         VMSTATE_END_OF_LIST()
 427     }
 428 };
 429
 430 const VMStateDescription vmstate_mos6522 = {
 431     .name = "mos6522",
 432     .version_id = 0,
 433     .minimum_version_id = 0,
 434     .fields = (VMStateField[]) {
 435         VMSTATE_UINT8(a, MOS6522State),
 436         VMSTATE_UINT8(b, MOS6522State),
 437         VMSTATE_UINT8(dira, MOS6522State),
 438         VMSTATE_UINT8(dirb, MOS6522State),
 439         VMSTATE_UINT8(sr, MOS6522State),
 440         VMSTATE_UINT8(acr, MOS6522State),
 441         VMSTATE_UINT8(pcr, MOS6522State),
 442         VMSTATE_UINT8(ifr, MOS6522State),
 443         VMSTATE_UINT8(ier, MOS6522State),
 444         VMSTATE_STRUCT_ARRAY(timers, MOS6522State, 2, 0,
 445                              vmstate_mos6522_timer, MOS6522Timer),
 446         VMSTATE_END_OF_LIST()
 447     }
 448 };
 449
 450 static void mos6522_reset(DeviceState *dev)
 451 {
 452     MOS6522State *s = MOS6522(dev);
 453
 454     s->b = 0;
 455     s->a = 0;
 456     s->dirb = 0xff;
 457     s->dira = 0;
 458     s->sr = 0;
 459     s->acr = 0;
 460     s->pcr = 0;
 461     s->ifr = 0;
 462     s->ier = 0;
 463     /* s->ier = T1_INT | SR_INT; */
 464
 465     s->timers[0].frequency = s->frequency;
 466     s->timers[0].latch = 0xffff;
 467     set_counter(s, &s->timers[0], 0xffff);
 468     timer_del(s->timers[0].timer);
 469
 470     s->timers[1].frequency = s->frequency;
 471     s->timers[1].latch = 0xffff;
 472     timer_del(s->timers[1].timer);
 473 }
 474
 475 static void mos6522_init(Object *obj)
 476 {
 477     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 478     MOS6522State *s = MOS6522(obj);
 479     int i;
 480
 481     memory_region_init_io(&s->mem, obj, &mos6522_ops, s, "mos6522", 0x10);
 482     sysbus_init_mmio(sbd, &s->mem);
 483     sysbus_init_irq(sbd, &s->irq);
 484
 485     for (i = 0; i < ARRAY_SIZE(s->timers); i++) {
 486         s->timers[i].index = i;
 487     }
 488
 489     s->timers[0].timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, mos6522_timer1, s);
 490     s->timers[1].timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, mos6522_timer2, s);
 491 }
 492
 493 static Property mos6522_properties[] = {
 494     DEFINE_PROP_UINT64("frequency", MOS6522State, frequency, 0),
 495     DEFINE_PROP_END_OF_LIST()
 496 };
 497
 498 static void mos6522_class_init(ObjectClass *oc, void *data)
 499 {
 500     DeviceClass *dc = DEVICE_CLASS(oc);
 501     MOS6522DeviceClass *mdc = MOS6522_DEVICE_CLASS(oc);
 502
 503     dc->reset = mos6522_reset;
 504     dc->vmsd = &vmstate_mos6522;
 505     device_class_set_props(dc, mos6522_properties);
 506     mdc->parent_reset = dc->reset;
 507     mdc->set_sr_int = mos6522_set_sr_int;
 508     mdc->portB_write = mos6522_portB_write;
 509     mdc->portA_write = mos6522_portA_write;
 510     mdc->update_irq = mos6522_update_irq;
 511     mdc->get_timer1_counter_value = mos6522_get_counter_value;
 512     mdc->get_timer2_counter_value = mos6522_get_counter_value;
 513     mdc->get_timer1_load_time = mos6522_get_load_time;
 514     mdc->get_timer2_load_time = mos6522_get_load_time;
 515 }
 516
 517 static const TypeInfo mos6522_type_info = {
 518     .name = TYPE_MOS6522,
 519     .parent = TYPE_SYS_BUS_DEVICE,
 520     .instance_size = sizeof(MOS6522State),
 521     .instance_init = mos6522_init,
 522     .abstract = true,
 523     .class_size = sizeof(MOS6522DeviceClass),
 524     .class_init = mos6522_class_init,
 525 };
 526
 527 static void mos6522_register_types(void)
 528 {
 529     type_register_static(&mos6522_type_info);
 530 }
 531
 532 type_init(mos6522_register_types)