hw/i8254.c

   1 /*
   2  * QEMU 8253/8254 interval timer emulation
   3  *
   4  * Copyright (c) 2003-2004 Fabrice Bellard
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #include "hw.h"
  25 #include "pc.h"
  26 #include "isa.h"
  27 #include "qemu-timer.h"
  28
  29 //#define DEBUG_PIT
  30
  31 #define RW_STATE_LSB 1
  32 #define RW_STATE_MSB 2
  33 #define RW_STATE_WORD0 3
  34 #define RW_STATE_WORD1 4
  35
  36 typedef struct PITChannelState {
  37     int count; /* can be 65536 */
  38     uint16_t latched_count;
  39     uint8_t count_latched;
  40     uint8_t status_latched;
  41     uint8_t status;
  42     uint8_t read_state;
  43     uint8_t write_state;
  44     uint8_t write_latch;
  45     uint8_t rw_mode;
  46     uint8_t mode;
  47     uint8_t bcd; /* not supported */
  48     uint8_t gate; /* timer start */
  49     int64_t count_load_time;
  50     /* irq handling */
  51     int64_t next_transition_time;
  52     QEMUTimer *irq_timer;
  53     qemu_irq irq;
  54 } PITChannelState;
  55
  56 typedef struct PITState {
  57     ISADevice dev;
  58     MemoryRegion ioports;
  59     uint32_t irq;
  60     uint32_t iobase;
  61     PITChannelState channels[3];
  62 } PITState;
  63
  64 static PITState pit_state;
  65
  66 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
  67
  68 static int pit_get_count(PITChannelState *s)
  69 {
  70     uint64_t d;
  71     int counter;
  72
  73     d = muldiv64(qemu_get_clock_ns(vm_clock) - s->count_load_time, PIT_FREQ,
  74                  get_ticks_per_sec());
  75     switch(s->mode) {
  76     case 0:
  77     case 1:
  78     case 4:
  79     case 5:
  80         counter = (s->count - d) & 0xffff;
  81         break;
  82     case 3:
  83         /* XXX: may be incorrect for odd counts */
  84         counter = s->count - ((2 * d) % s->count);
  85         break;
  86     default:
  87         counter = s->count - (d % s->count);
  88         break;
  89     }
  90     return counter;
  91 }
  92
  93 /* get pit output bit */
  94 static int pit_get_out1(PITChannelState *s, int64_t current_time)
  95 {
  96     uint64_t d;
  97     int out;
  98
  99     d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
 100                  get_ticks_per_sec());
 101     switch(s->mode) {
 102     default:
 103     case 0:
 104         out = (d >= s->count);
 105         break;
 106     case 1:
 107         out = (d < s->count);
 108         break;
 109     case 2:
 110         if ((d % s->count) == 0 && d != 0)
 111             out = 1;
 112         else
 113             out = 0;
 114         break;
 115     case 3:
 116         out = (d % s->count) < ((s->count + 1) >> 1);
 117         break;
 118     case 4:
 119     case 5:
 120         out = (d == s->count);
 121         break;
 122     }
 123     return out;
 124 }
 125
 126 int pit_get_out(ISADevice *dev, int channel, int64_t current_time)
 127 {
 128     PITState *pit = DO_UPCAST(PITState, dev, dev);
 129     PITChannelState *s = &pit->channels[channel];
 130     return pit_get_out1(s, current_time);
 131 }
 132
 133 /* return -1 if no transition will occur.  */
 134 static int64_t pit_get_next_transition_time(PITChannelState *s,
 135                                             int64_t current_time)
 136 {
 137     uint64_t d, next_time, base;
 138     int period2;
 139
 140     d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
 141                  get_ticks_per_sec());
 142     switch(s->mode) {
 143     default:
 144     case 0:
 145     case 1:
 146         if (d < s->count)
 147             next_time = s->count;
 148         else
 149             return -1;
 150         break;
 151     case 2:
 152         base = (d / s->count) * s->count;
 153         if ((d - base) == 0 && d != 0)
 154             next_time = base + s->count;
 155         else
 156             next_time = base + s->count + 1;
 157         break;
 158     case 3:
 159         base = (d / s->count) * s->count;
 160         period2 = ((s->count + 1) >> 1);
 161         if ((d - base) < period2)
 162             next_time = base + period2;
 163         else
 164             next_time = base + s->count;
 165         break;
 166     case 4:
 167     case 5:
 168         if (d < s->count)
 169             next_time = s->count;
 170         else if (d == s->count)
 171             next_time = s->count + 1;
 172         else
 173             return -1;
 174         break;
 175     }
 176     /* convert to timer units */
 177     next_time = s->count_load_time + muldiv64(next_time, get_ticks_per_sec(),
 178                                               PIT_FREQ);
 179     /* fix potential rounding problems */
 180     /* XXX: better solution: use a clock at PIT_FREQ Hz */
 181     if (next_time <= current_time)
 182         next_time = current_time + 1;
 183     return next_time;
 184 }
 185
 186 /* val must be 0 or 1 */
 187 void pit_set_gate(ISADevice *dev, int channel, int val)
 188 {
 189     PITState *pit = DO_UPCAST(PITState, dev, dev);
 190     PITChannelState *s = &pit->channels[channel];
 191
 192     switch(s->mode) {
 193     default:
 194     case 0:
 195     case 4:
 196         /* XXX: just disable/enable counting */
 197         break;
 198     case 1:
 199     case 5:
 200         if (s->gate < val) {
 201             /* restart counting on rising edge */
 202             s->count_load_time = qemu_get_clock_ns(vm_clock);
 203             pit_irq_timer_update(s, s->count_load_time);
 204         }
 205         break;
 206     case 2:
 207     case 3:
 208         if (s->gate < val) {
 209             /* restart counting on rising edge */
 210             s->count_load_time = qemu_get_clock_ns(vm_clock);
 211             pit_irq_timer_update(s, s->count_load_time);
 212         }
 213         /* XXX: disable/enable counting */
 214         break;
 215     }
 216     s->gate = val;
 217 }
 218
 219 int pit_get_gate(ISADevice *dev, int channel)
 220 {
 221     PITState *pit = DO_UPCAST(PITState, dev, dev);
 222     PITChannelState *s = &pit->channels[channel];
 223     return s->gate;
 224 }
 225
 226 int pit_get_initial_count(ISADevice *dev, int channel)
 227 {
 228     PITState *pit = DO_UPCAST(PITState, dev, dev);
 229     PITChannelState *s = &pit->channels[channel];
 230     return s->count;
 231 }
 232
 233 int pit_get_mode(ISADevice *dev, int channel)
 234 {
 235     PITState *pit = DO_UPCAST(PITState, dev, dev);
 236     PITChannelState *s = &pit->channels[channel];
 237     return s->mode;
 238 }
 239
 240 static inline void pit_load_count(PITChannelState *s, int val)
 241 {
 242     if (val == 0)
 243         val = 0x10000;
 244     s->count_load_time = qemu_get_clock_ns(vm_clock);
 245     s->count = val;
 246     pit_irq_timer_update(s, s->count_load_time);
 247 }
 248
 249 /* if already latched, do not latch again */
 250 static void pit_latch_count(PITChannelState *s)
 251 {
 252     if (!s->count_latched) {
 253         s->latched_count = pit_get_count(s);
 254         s->count_latched = s->rw_mode;
 255     }
 256 }
 257
 258 static void pit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 259 {
 260     PITState *pit = opaque;
 261     int channel, access;
 262     PITChannelState *s;
 263
 264     addr &= 3;
 265     if (addr == 3) {
 266         channel = val >> 6;
 267         if (channel == 3) {
 268             /* read back command */
 269             for(channel = 0; channel < 3; channel++) {
 270                 s = &pit->channels[channel];
 271                 if (val & (2 << channel)) {
 272                     if (!(val & 0x20)) {
 273                         pit_latch_count(s);
 274                     }
 275                     if (!(val & 0x10) && !s->status_latched) {
 276                         /* status latch */
 277                         /* XXX: add BCD and null count */
 278                         s->status =  (pit_get_out1(s, qemu_get_clock_ns(vm_clock)) << 7) |
 279                             (s->rw_mode << 4) |
 280                             (s->mode << 1) |
 281                             s->bcd;
 282                         s->status_latched = 1;
 283                     }
 284                 }
 285             }
 286         } else {
 287             s = &pit->channels[channel];
 288             access = (val >> 4) & 3;
 289             if (access == 0) {
 290                 pit_latch_count(s);
 291             } else {
 292                 s->rw_mode = access;
 293                 s->read_state = access;
 294                 s->write_state = access;
 295
 296                 s->mode = (val >> 1) & 7;
 297                 s->bcd = val & 1;
 298                 /* XXX: update irq timer ? */
 299             }
 300         }
 301     } else {
 302         s = &pit->channels[addr];
 303         switch(s->write_state) {
 304         default:
 305         case RW_STATE_LSB:
 306             pit_load_count(s, val);
 307             break;
 308         case RW_STATE_MSB:
 309             pit_load_count(s, val << 8);
 310             break;
 311         case RW_STATE_WORD0:
 312             s->write_latch = val;
 313             s->write_state = RW_STATE_WORD1;
 314             break;
 315         case RW_STATE_WORD1:
 316             pit_load_count(s, s->write_latch | (val << 8));
 317             s->write_state = RW_STATE_WORD0;
 318             break;
 319         }
 320     }
 321 }
 322
 323 static uint32_t pit_ioport_read(void *opaque, uint32_t addr)
 324 {
 325     PITState *pit = opaque;
 326     int ret, count;
 327     PITChannelState *s;
 328
 329     addr &= 3;
 330     s = &pit->channels[addr];
 331     if (s->status_latched) {
 332         s->status_latched = 0;
 333         ret = s->status;
 334     } else if (s->count_latched) {
 335         switch(s->count_latched) {
 336         default:
 337         case RW_STATE_LSB:
 338             ret = s->latched_count & 0xff;
 339             s->count_latched = 0;
 340             break;
 341         case RW_STATE_MSB:
 342             ret = s->latched_count >> 8;
 343             s->count_latched = 0;
 344             break;
 345         case RW_STATE_WORD0:
 346             ret = s->latched_count & 0xff;
 347             s->count_latched = RW_STATE_MSB;
 348             break;
 349         }
 350     } else {
 351         switch(s->read_state) {
 352         default:
 353         case RW_STATE_LSB:
 354             count = pit_get_count(s);
 355             ret = count & 0xff;
 356             break;
 357         case RW_STATE_MSB:
 358             count = pit_get_count(s);
 359             ret = (count >> 8) & 0xff;
 360             break;
 361         case RW_STATE_WORD0:
 362             count = pit_get_count(s);
 363             ret = count & 0xff;
 364             s->read_state = RW_STATE_WORD1;
 365             break;
 366         case RW_STATE_WORD1:
 367             count = pit_get_count(s);
 368             ret = (count >> 8) & 0xff;
 369             s->read_state = RW_STATE_WORD0;
 370             break;
 371         }
 372     }
 373     return ret;
 374 }
 375
 376 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time)
 377 {
 378     int64_t expire_time;
 379     int irq_level;
 380
 381     if (!s->irq_timer)
 382         return;
 383     expire_time = pit_get_next_transition_time(s, current_time);
 384     irq_level = pit_get_out1(s, current_time);
 385     qemu_set_irq(s->irq, irq_level);
 386 #ifdef DEBUG_PIT
 387     printf("irq_level=%d next_delay=%f\n",
 388            irq_level,
 389            (double)(expire_time - current_time) / get_ticks_per_sec());
 390 #endif
 391     s->next_transition_time = expire_time;
 392     if (expire_time != -1)
 393         qemu_mod_timer(s->irq_timer, expire_time);
 394     else
 395         qemu_del_timer(s->irq_timer);
 396 }
 397
 398 static void pit_irq_timer(void *opaque)
 399 {
 400     PITChannelState *s = opaque;
 401
 402     pit_irq_timer_update(s, s->next_transition_time);
 403 }
 404
 405 static const VMStateDescription vmstate_pit_channel = {
 406     .name = "pit channel",
 407     .version_id = 2,
 408     .minimum_version_id = 2,
 409     .minimum_version_id_old = 2,
 410     .fields      = (VMStateField []) {
 411         VMSTATE_INT32(count, PITChannelState),
 412         VMSTATE_UINT16(latched_count, PITChannelState),
 413         VMSTATE_UINT8(count_latched, PITChannelState),
 414         VMSTATE_UINT8(status_latched, PITChannelState),
 415         VMSTATE_UINT8(status, PITChannelState),
 416         VMSTATE_UINT8(read_state, PITChannelState),
 417         VMSTATE_UINT8(write_state, PITChannelState),
 418         VMSTATE_UINT8(write_latch, PITChannelState),
 419         VMSTATE_UINT8(rw_mode, PITChannelState),
 420         VMSTATE_UINT8(mode, PITChannelState),
 421         VMSTATE_UINT8(bcd, PITChannelState),
 422         VMSTATE_UINT8(gate, PITChannelState),
 423         VMSTATE_INT64(count_load_time, PITChannelState),
 424         VMSTATE_INT64(next_transition_time, PITChannelState),
 425         VMSTATE_END_OF_LIST()
 426     }
 427 };
 428
 429 static int pit_load_old(QEMUFile *f, void *opaque, int version_id)
 430 {
 431     PITState *pit = opaque;
 432     PITChannelState *s;
 433     int i;
 434
 435     if (version_id != 1)
 436         return -EINVAL;
 437
 438     for(i = 0; i < 3; i++) {
 439         s = &pit->channels[i];
 440         s->count=qemu_get_be32(f);
 441         qemu_get_be16s(f, &s->latched_count);
 442         qemu_get_8s(f, &s->count_latched);
 443         qemu_get_8s(f, &s->status_latched);
 444         qemu_get_8s(f, &s->status);
 445         qemu_get_8s(f, &s->read_state);
 446         qemu_get_8s(f, &s->write_state);
 447         qemu_get_8s(f, &s->write_latch);
 448         qemu_get_8s(f, &s->rw_mode);
 449         qemu_get_8s(f, &s->mode);
 450         qemu_get_8s(f, &s->bcd);
 451         qemu_get_8s(f, &s->gate);
 452         s->count_load_time=qemu_get_be64(f);
 453         if (s->irq_timer) {
 454             s->next_transition_time=qemu_get_be64(f);
 455             qemu_get_timer(f, s->irq_timer);
 456         }
 457     }
 458     return 0;
 459 }
 460
 461 static const VMStateDescription vmstate_pit = {
 462     .name = "i8254",
 463     .version_id = 2,
 464     .minimum_version_id = 2,
 465     .minimum_version_id_old = 1,
 466     .load_state_old = pit_load_old,
 467     .fields      = (VMStateField []) {
 468         VMSTATE_STRUCT_ARRAY(channels, PITState, 3, 2, vmstate_pit_channel, PITChannelState),
 469         VMSTATE_TIMER(channels[0].irq_timer, PITState),
 470         VMSTATE_END_OF_LIST()
 471     }
 472 };
 473
 474 static void pit_reset(DeviceState *dev)
 475 {
 476     PITState *pit = container_of(dev, PITState, dev.qdev);
 477     PITChannelState *s;
 478     int i;
 479
 480     for(i = 0;i < 3; i++) {
 481         s = &pit->channels[i];
 482         s->mode = 3;
 483         s->gate = (i != 2);
 484         pit_load_count(s, 0);
 485     }
 486 }
 487
 488 /* When HPET is operating in legacy mode, i8254 timer0 is disabled */
 489 void hpet_pit_disable(void) {
 490     PITChannelState *s;
 491     s = &pit_state.channels[0];
 492     if (s->irq_timer)
 493         qemu_del_timer(s->irq_timer);
 494 }
 495
 496 /* When HPET is reset or leaving legacy mode, it must reenable i8254
 497  * timer 0
 498  */
 499
 500 void hpet_pit_enable(void)
 501 {
 502     PITState *pit = &pit_state;
 503     PITChannelState *s;
 504     s = &pit->channels[0];
 505     s->mode = 3;
 506     s->gate = 1;
 507     pit_load_count(s, 0);
 508 }
 509
 510 static const MemoryRegionPortio pit_portio[] = {
 511     { 0, 4, 1, .write = pit_ioport_write },
 512     { 0, 3, 1, .read = pit_ioport_read },
 513     PORTIO_END_OF_LIST()
 514 };
 515
 516 static const MemoryRegionOps pit_ioport_ops = {
 517     .old_portio = pit_portio
 518 };
 519
 520 static int pit_initfn(ISADevice *dev)
 521 {
 522     PITState *pit = DO_UPCAST(PITState, dev, dev);
 523     PITChannelState *s;
 524
 525     s = &pit->channels[0];
 526     /* the timer 0 is connected to an IRQ */
 527     s->irq_timer = qemu_new_timer_ns(vm_clock, pit_irq_timer, s);
 528     s->irq = isa_get_irq(dev, pit->irq);
 529
 530     memory_region_init_io(&pit->ioports, &pit_ioport_ops, pit, "pit", 4);
 531     isa_register_ioport(dev, &pit->ioports, pit->iobase);
 532
 533     qdev_set_legacy_instance_id(&dev->qdev, pit->iobase, 2);
 534
 535     return 0;
 536 }
 537
 538 static ISADeviceInfo pit_info = {
 539     .qdev.name     = "isa-pit",
 540     .qdev.size     = sizeof(PITState),
 541     .qdev.vmsd     = &vmstate_pit,
 542     .qdev.reset    = pit_reset,
 543     .qdev.no_user  = 1,
 544     .init          = pit_initfn,
 545     .qdev.props = (Property[]) {
 546         DEFINE_PROP_UINT32("irq", PITState, irq,  -1),
 547         DEFINE_PROP_HEX32("iobase", PITState, iobase,  -1),
 548         DEFINE_PROP_END_OF_LIST(),
 549     },
 550 };
 551
 552 static void pit_register(void)
 553 {
 554     isa_qdev_register(&pit_info);
 555 }
 556 device_init(pit_register)