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 struct PITState {
  57     PITChannelState channels[3];
  58 };
  59
  60 static PITState pit_state;
  61
  62 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
  63
  64 static int pit_get_count(PITChannelState *s)
  65 {
  66     uint64_t d;
  67     int counter;
  68
  69     d = muldiv64(qemu_get_clock(vm_clock) - s->count_load_time, PIT_FREQ,
  70                  get_ticks_per_sec());
  71     switch(s->mode) {
  72     case 0:
  73     case 1:
  74     case 4:
  75     case 5:
  76         counter = (s->count - d) & 0xffff;
  77         break;
  78     case 3:
  79         /* XXX: may be incorrect for odd counts */
  80         counter = s->count - ((2 * d) % s->count);
  81         break;
  82     default:
  83         counter = s->count - (d % s->count);
  84         break;
  85     }
  86     return counter;
  87 }
  88
  89 /* get pit output bit */
  90 static int pit_get_out1(PITChannelState *s, int64_t current_time)
  91 {
  92     uint64_t d;
  93     int out;
  94
  95     d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
  96                  get_ticks_per_sec());
  97     switch(s->mode) {
  98     default:
  99     case 0:
 100         out = (d >= s->count);
 101         break;
 102     case 1:
 103         out = (d < s->count);
 104         break;
 105     case 2:
 106         if ((d % s->count) == 0 && d != 0)
 107             out = 1;
 108         else
 109             out = 0;
 110         break;
 111     case 3:
 112         out = (d % s->count) < ((s->count + 1) >> 1);
 113         break;
 114     case 4:
 115     case 5:
 116         out = (d == s->count);
 117         break;
 118     }
 119     return out;
 120 }
 121
 122 int pit_get_out(PITState *pit, int channel, int64_t current_time)
 123 {
 124     PITChannelState *s = &pit->channels[channel];
 125     return pit_get_out1(s, current_time);
 126 }
 127
 128 /* return -1 if no transition will occur.  */
 129 static int64_t pit_get_next_transition_time(PITChannelState *s,
 130                                             int64_t current_time)
 131 {
 132     uint64_t d, next_time, base;
 133     int period2;
 134
 135     d = muldiv64(current_time - s->count_load_time, PIT_FREQ,
 136                  get_ticks_per_sec());
 137     switch(s->mode) {
 138     default:
 139     case 0:
 140     case 1:
 141         if (d < s->count)
 142             next_time = s->count;
 143         else
 144             return -1;
 145         break;
 146     case 2:
 147         base = (d / s->count) * s->count;
 148         if ((d - base) == 0 && d != 0)
 149             next_time = base + s->count;
 150         else
 151             next_time = base + s->count + 1;
 152         break;
 153     case 3:
 154         base = (d / s->count) * s->count;
 155         period2 = ((s->count + 1) >> 1);
 156         if ((d - base) < period2)
 157             next_time = base + period2;
 158         else
 159             next_time = base + s->count;
 160         break;
 161     case 4:
 162     case 5:
 163         if (d < s->count)
 164             next_time = s->count;
 165         else if (d == s->count)
 166             next_time = s->count + 1;
 167         else
 168             return -1;
 169         break;
 170     }
 171     /* convert to timer units */
 172     next_time = s->count_load_time + muldiv64(next_time, get_ticks_per_sec(),
 173                                               PIT_FREQ);
 174     /* fix potential rounding problems */
 175     /* XXX: better solution: use a clock at PIT_FREQ Hz */
 176     if (next_time <= current_time)
 177         next_time = current_time + 1;
 178     return next_time;
 179 }
 180
 181 /* val must be 0 or 1 */
 182 void pit_set_gate(PITState *pit, int channel, int val)
 183 {
 184     PITChannelState *s = &pit->channels[channel];
 185
 186     switch(s->mode) {
 187     default:
 188     case 0:
 189     case 4:
 190         /* XXX: just disable/enable counting */
 191         break;
 192     case 1:
 193     case 5:
 194         if (s->gate < val) {
 195             /* restart counting on rising edge */
 196             s->count_load_time = qemu_get_clock(vm_clock);
 197             pit_irq_timer_update(s, s->count_load_time);
 198         }
 199         break;
 200     case 2:
 201     case 3:
 202         if (s->gate < val) {
 203             /* restart counting on rising edge */
 204             s->count_load_time = qemu_get_clock(vm_clock);
 205             pit_irq_timer_update(s, s->count_load_time);
 206         }
 207         /* XXX: disable/enable counting */
 208         break;
 209     }
 210     s->gate = val;
 211 }
 212
 213 int pit_get_gate(PITState *pit, int channel)
 214 {
 215     PITChannelState *s = &pit->channels[channel];
 216     return s->gate;
 217 }
 218
 219 int pit_get_initial_count(PITState *pit, int channel)
 220 {
 221     PITChannelState *s = &pit->channels[channel];
 222     return s->count;
 223 }
 224
 225 int pit_get_mode(PITState *pit, int channel)
 226 {
 227     PITChannelState *s = &pit->channels[channel];
 228     return s->mode;
 229 }
 230
 231 static inline void pit_load_count(PITChannelState *s, int val)
 232 {
 233     if (val == 0)
 234         val = 0x10000;
 235     s->count_load_time = qemu_get_clock(vm_clock);
 236     s->count = val;
 237     pit_irq_timer_update(s, s->count_load_time);
 238 }
 239
 240 /* if already latched, do not latch again */
 241 static void pit_latch_count(PITChannelState *s)
 242 {
 243     if (!s->count_latched) {
 244         s->latched_count = pit_get_count(s);
 245         s->count_latched = s->rw_mode;
 246     }
 247 }
 248
 249 static void pit_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 250 {
 251     PITState *pit = opaque;
 252     int channel, access;
 253     PITChannelState *s;
 254
 255     addr &= 3;
 256     if (addr == 3) {
 257         channel = val >> 6;
 258         if (channel == 3) {
 259             /* read back command */
 260             for(channel = 0; channel < 3; channel++) {
 261                 s = &pit->channels[channel];
 262                 if (val & (2 << channel)) {
 263                     if (!(val & 0x20)) {
 264                         pit_latch_count(s);
 265                     }
 266                     if (!(val & 0x10) && !s->status_latched) {
 267                         /* status latch */
 268                         /* XXX: add BCD and null count */
 269                         s->status =  (pit_get_out1(s, qemu_get_clock(vm_clock)) << 7) |
 270                             (s->rw_mode << 4) |
 271                             (s->mode << 1) |
 272                             s->bcd;
 273                         s->status_latched = 1;
 274                     }
 275                 }
 276             }
 277         } else {
 278             s = &pit->channels[channel];
 279             access = (val >> 4) & 3;
 280             if (access == 0) {
 281                 pit_latch_count(s);
 282             } else {
 283                 s->rw_mode = access;
 284                 s->read_state = access;
 285                 s->write_state = access;
 286
 287                 s->mode = (val >> 1) & 7;
 288                 s->bcd = val & 1;
 289                 /* XXX: update irq timer ? */
 290             }
 291         }
 292     } else {
 293         s = &pit->channels[addr];
 294         switch(s->write_state) {
 295         default:
 296         case RW_STATE_LSB:
 297             pit_load_count(s, val);
 298             break;
 299         case RW_STATE_MSB:
 300             pit_load_count(s, val << 8);
 301             break;
 302         case RW_STATE_WORD0:
 303             s->write_latch = val;
 304             s->write_state = RW_STATE_WORD1;
 305             break;
 306         case RW_STATE_WORD1:
 307             pit_load_count(s, s->write_latch | (val << 8));
 308             s->write_state = RW_STATE_WORD0;
 309             break;
 310         }
 311     }
 312 }
 313
 314 static uint32_t pit_ioport_read(void *opaque, uint32_t addr)
 315 {
 316     PITState *pit = opaque;
 317     int ret, count;
 318     PITChannelState *s;
 319
 320     addr &= 3;
 321     s = &pit->channels[addr];
 322     if (s->status_latched) {
 323         s->status_latched = 0;
 324         ret = s->status;
 325     } else if (s->count_latched) {
 326         switch(s->count_latched) {
 327         default:
 328         case RW_STATE_LSB:
 329             ret = s->latched_count & 0xff;
 330             s->count_latched = 0;
 331             break;
 332         case RW_STATE_MSB:
 333             ret = s->latched_count >> 8;
 334             s->count_latched = 0;
 335             break;
 336         case RW_STATE_WORD0:
 337             ret = s->latched_count & 0xff;
 338             s->count_latched = RW_STATE_MSB;
 339             break;
 340         }
 341     } else {
 342         switch(s->read_state) {
 343         default:
 344         case RW_STATE_LSB:
 345             count = pit_get_count(s);
 346             ret = count & 0xff;
 347             break;
 348         case RW_STATE_MSB:
 349             count = pit_get_count(s);
 350             ret = (count >> 8) & 0xff;
 351             break;
 352         case RW_STATE_WORD0:
 353             count = pit_get_count(s);
 354             ret = count & 0xff;
 355             s->read_state = RW_STATE_WORD1;
 356             break;
 357         case RW_STATE_WORD1:
 358             count = pit_get_count(s);
 359             ret = (count >> 8) & 0xff;
 360             s->read_state = RW_STATE_WORD0;
 361             break;
 362         }
 363     }
 364     return ret;
 365 }
 366
 367 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time)
 368 {
 369     int64_t expire_time;
 370     int irq_level;
 371
 372     if (!s->irq_timer)
 373         return;
 374     expire_time = pit_get_next_transition_time(s, current_time);
 375     irq_level = pit_get_out1(s, current_time);
 376     qemu_set_irq(s->irq, irq_level);
 377 #ifdef DEBUG_PIT
 378     printf("irq_level=%d next_delay=%f\n",
 379            irq_level,
 380            (double)(expire_time - current_time) / get_ticks_per_sec());
 381 #endif
 382     s->next_transition_time = expire_time;
 383     if (expire_time != -1)
 384         qemu_mod_timer(s->irq_timer, expire_time);
 385     else
 386         qemu_del_timer(s->irq_timer);
 387 }
 388
 389 static void pit_irq_timer(void *opaque)
 390 {
 391     PITChannelState *s = opaque;
 392
 393     pit_irq_timer_update(s, s->next_transition_time);
 394 }
 395
 396 static const VMStateDescription vmstate_pit_channel = {
 397     .name = "pit channel",
 398     .version_id = 2,
 399     .minimum_version_id = 2,
 400     .minimum_version_id_old = 2,
 401     .fields      = (VMStateField []) {
 402         VMSTATE_INT32(count, PITChannelState),
 403         VMSTATE_UINT16(latched_count, PITChannelState),
 404         VMSTATE_UINT8(count_latched, PITChannelState),
 405         VMSTATE_UINT8(status_latched, PITChannelState),
 406         VMSTATE_UINT8(status, PITChannelState),
 407         VMSTATE_UINT8(read_state, PITChannelState),
 408         VMSTATE_UINT8(write_state, PITChannelState),
 409         VMSTATE_UINT8(write_latch, PITChannelState),
 410         VMSTATE_UINT8(rw_mode, PITChannelState),
 411         VMSTATE_UINT8(mode, PITChannelState),
 412         VMSTATE_UINT8(bcd, PITChannelState),
 413         VMSTATE_UINT8(gate, PITChannelState),
 414         VMSTATE_INT64(count_load_time, PITChannelState),
 415         VMSTATE_INT64(next_transition_time, PITChannelState),
 416         VMSTATE_END_OF_LIST()
 417     }
 418 };
 419
 420 static int pit_load_old(QEMUFile *f, void *opaque, int version_id)
 421 {
 422     PITState *pit = opaque;
 423     PITChannelState *s;
 424     int i;
 425
 426     if (version_id != 1)
 427         return -EINVAL;
 428
 429     for(i = 0; i < 3; i++) {
 430         s = &pit->channels[i];
 431         s->count=qemu_get_be32(f);
 432         qemu_get_be16s(f, &s->latched_count);
 433         qemu_get_8s(f, &s->count_latched);
 434         qemu_get_8s(f, &s->status_latched);
 435         qemu_get_8s(f, &s->status);
 436         qemu_get_8s(f, &s->read_state);
 437         qemu_get_8s(f, &s->write_state);
 438         qemu_get_8s(f, &s->write_latch);
 439         qemu_get_8s(f, &s->rw_mode);
 440         qemu_get_8s(f, &s->mode);
 441         qemu_get_8s(f, &s->bcd);
 442         qemu_get_8s(f, &s->gate);
 443         s->count_load_time=qemu_get_be64(f);
 444         if (s->irq_timer) {
 445             s->next_transition_time=qemu_get_be64(f);
 446             qemu_get_timer(f, s->irq_timer);
 447         }
 448     }
 449     return 0;
 450 }
 451
 452 static const VMStateDescription vmstate_pit = {
 453     .name = "i8254",
 454     .version_id = 2,
 455     .minimum_version_id = 2,
 456     .minimum_version_id_old = 1,
 457     .load_state_old = pit_load_old,
 458     .fields      = (VMStateField []) {
 459         VMSTATE_STRUCT_ARRAY(channels, PITState, 3, 2, vmstate_pit_channel, PITChannelState),
 460         VMSTATE_TIMER(channels[0].irq_timer, PITState),
 461         VMSTATE_END_OF_LIST()
 462     }
 463 };
 464
 465 static void pit_reset(void *opaque)
 466 {
 467     PITState *pit = opaque;
 468     PITChannelState *s;
 469     int i;
 470
 471     for(i = 0;i < 3; i++) {
 472         s = &pit->channels[i];
 473         s->mode = 3;
 474         s->gate = (i != 2);
 475         pit_load_count(s, 0);
 476     }
 477 }
 478
 479 /* When HPET is operating in legacy mode, i8254 timer0 is disabled */
 480 void hpet_pit_disable(void) {
 481     PITChannelState *s;
 482     s = &pit_state.channels[0];
 483     if (s->irq_timer)
 484         qemu_del_timer(s->irq_timer);
 485 }
 486
 487 /* When HPET is reset or leaving legacy mode, it must reenable i8254
 488  * timer 0
 489  */
 490
 491 void hpet_pit_enable(void)
 492 {
 493     PITState *pit = &pit_state;
 494     PITChannelState *s;
 495     s = &pit->channels[0];
 496     s->mode = 3;
 497     s->gate = 1;
 498     pit_load_count(s, 0);
 499 }
 500
 501 PITState *pit_init(int base, qemu_irq irq)
 502 {
 503     PITState *pit = &pit_state;
 504     PITChannelState *s;
 505
 506     s = &pit->channels[0];
 507     /* the timer 0 is connected to an IRQ */
 508     s->irq_timer = qemu_new_timer(vm_clock, pit_irq_timer, s);
 509     s->irq = irq;
 510
 511     vmstate_register(base, &vmstate_pit, pit);
 512     qemu_register_reset(pit_reset, pit);
 513     register_ioport_write(base, 4, 1, pit_ioport_write, pit);
 514     register_ioport_read(base, 3, 1, pit_ioport_read, pit);
 515
 516     return pit;
 517 }