hw/timer/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 "qemu/osdep.h"
  25 #include "hw/hw.h"
  26 #include "hw/isa/isa.h"
  27 #include "qemu/timer.h"
  28 #include "hw/timer/i8254.h"
  29 #include "hw/timer/i8254_internal.h"
  30
  31 //#define DEBUG_PIT
  32
  33 #define RW_STATE_LSB 1
  34 #define RW_STATE_MSB 2
  35 #define RW_STATE_WORD0 3
  36 #define RW_STATE_WORD1 4
  37
  38 #define PIT_CLASS(class) OBJECT_CLASS_CHECK(PITClass, (class), TYPE_I8254)
  39 #define PIT_GET_CLASS(obj) OBJECT_GET_CLASS(PITClass, (obj), TYPE_I8254)
  40
  41 typedef struct PITClass {
  42     PITCommonClass parent_class;
  43
  44     DeviceRealize parent_realize;
  45 } PITClass;
  46
  47 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time);
  48
  49 static int pit_get_count(PITChannelState *s)
  50 {
  51     uint64_t d;
  52     int counter;
  53
  54     d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->count_load_time, PIT_FREQ,
  55                  NANOSECONDS_PER_SECOND);
  56     switch(s->mode) {
  57     case 0:
  58     case 1:
  59     case 4:
  60     case 5:
  61         counter = (s->count - d) & 0xffff;
  62         break;
  63     case 3:
  64         /* XXX: may be incorrect for odd counts */
  65         counter = s->count - ((2 * d) % s->count);
  66         break;
  67     default:
  68         counter = s->count - (d % s->count);
  69         break;
  70     }
  71     return counter;
  72 }
  73
  74 /* val must be 0 or 1 */
  75 static void pit_set_channel_gate(PITCommonState *s, PITChannelState *sc,
  76                                  int val)
  77 {
  78     switch (sc->mode) {
  79     default:
  80     case 0:
  81     case 4:
  82         /* XXX: just disable/enable counting */
  83         break;
  84     case 1:
  85     case 5:
  86         if (sc->gate < val) {
  87             /* restart counting on rising edge */
  88             sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
  89             pit_irq_timer_update(sc, sc->count_load_time);
  90         }
  91         break;
  92     case 2:
  93     case 3:
  94         if (sc->gate < val) {
  95             /* restart counting on rising edge */
  96             sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
  97             pit_irq_timer_update(sc, sc->count_load_time);
  98         }
  99         /* XXX: disable/enable counting */
 100         break;
 101     }
 102     sc->gate = val;
 103 }
 104
 105 static inline void pit_load_count(PITChannelState *s, int val)
 106 {
 107     if (val == 0)
 108         val = 0x10000;
 109     s->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 110     s->count = val;
 111     pit_irq_timer_update(s, s->count_load_time);
 112 }
 113
 114 /* if already latched, do not latch again */
 115 static void pit_latch_count(PITChannelState *s)
 116 {
 117     if (!s->count_latched) {
 118         s->latched_count = pit_get_count(s);
 119         s->count_latched = s->rw_mode;
 120     }
 121 }
 122
 123 static void pit_ioport_write(void *opaque, hwaddr addr,
 124                              uint64_t val, unsigned size)
 125 {
 126     PITCommonState *pit = opaque;
 127     int channel, access;
 128     PITChannelState *s;
 129
 130     addr &= 3;
 131     if (addr == 3) {
 132         channel = val >> 6;
 133         if (channel == 3) {
 134             /* read back command */
 135             for(channel = 0; channel < 3; channel++) {
 136                 s = &pit->channels[channel];
 137                 if (val & (2 << channel)) {
 138                     if (!(val & 0x20)) {
 139                         pit_latch_count(s);
 140                     }
 141                     if (!(val & 0x10) && !s->status_latched) {
 142                         /* status latch */
 143                         /* XXX: add BCD and null count */
 144                         s->status =
 145                             (pit_get_out(s,
 146                                          qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) << 7) |
 147                             (s->rw_mode << 4) |
 148                             (s->mode << 1) |
 149                             s->bcd;
 150                         s->status_latched = 1;
 151                     }
 152                 }
 153             }
 154         } else {
 155             s = &pit->channels[channel];
 156             access = (val >> 4) & 3;
 157             if (access == 0) {
 158                 pit_latch_count(s);
 159             } else {
 160                 s->rw_mode = access;
 161                 s->read_state = access;
 162                 s->write_state = access;
 163
 164                 s->mode = (val >> 1) & 7;
 165                 s->bcd = val & 1;
 166                 /* XXX: update irq timer ? */
 167             }
 168         }
 169     } else {
 170         s = &pit->channels[addr];
 171         switch(s->write_state) {
 172         default:
 173         case RW_STATE_LSB:
 174             pit_load_count(s, val);
 175             break;
 176         case RW_STATE_MSB:
 177             pit_load_count(s, val << 8);
 178             break;
 179         case RW_STATE_WORD0:
 180             s->write_latch = val;
 181             s->write_state = RW_STATE_WORD1;
 182             break;
 183         case RW_STATE_WORD1:
 184             pit_load_count(s, s->write_latch | (val << 8));
 185             s->write_state = RW_STATE_WORD0;
 186             break;
 187         }
 188     }
 189 }
 190
 191 static uint64_t pit_ioport_read(void *opaque, hwaddr addr,
 192                                 unsigned size)
 193 {
 194     PITCommonState *pit = opaque;
 195     int ret, count;
 196     PITChannelState *s;
 197
 198     addr &= 3;
 199
 200     if (addr == 3) {
 201         /* Mode/Command register is write only, read is ignored */
 202         return 0;
 203     }
 204
 205     s = &pit->channels[addr];
 206     if (s->status_latched) {
 207         s->status_latched = 0;
 208         ret = s->status;
 209     } else if (s->count_latched) {
 210         switch(s->count_latched) {
 211         default:
 212         case RW_STATE_LSB:
 213             ret = s->latched_count & 0xff;
 214             s->count_latched = 0;
 215             break;
 216         case RW_STATE_MSB:
 217             ret = s->latched_count >> 8;
 218             s->count_latched = 0;
 219             break;
 220         case RW_STATE_WORD0:
 221             ret = s->latched_count & 0xff;
 222             s->count_latched = RW_STATE_MSB;
 223             break;
 224         }
 225     } else {
 226         switch(s->read_state) {
 227         default:
 228         case RW_STATE_LSB:
 229             count = pit_get_count(s);
 230             ret = count & 0xff;
 231             break;
 232         case RW_STATE_MSB:
 233             count = pit_get_count(s);
 234             ret = (count >> 8) & 0xff;
 235             break;
 236         case RW_STATE_WORD0:
 237             count = pit_get_count(s);
 238             ret = count & 0xff;
 239             s->read_state = RW_STATE_WORD1;
 240             break;
 241         case RW_STATE_WORD1:
 242             count = pit_get_count(s);
 243             ret = (count >> 8) & 0xff;
 244             s->read_state = RW_STATE_WORD0;
 245             break;
 246         }
 247     }
 248     return ret;
 249 }
 250
 251 static void pit_irq_timer_update(PITChannelState *s, int64_t current_time)
 252 {
 253     int64_t expire_time;
 254     int irq_level;
 255
 256     if (!s->irq_timer || s->irq_disabled) {
 257         return;
 258     }
 259     expire_time = pit_get_next_transition_time(s, current_time);
 260     irq_level = pit_get_out(s, current_time);
 261     qemu_set_irq(s->irq, irq_level);
 262 #ifdef DEBUG_PIT
 263     printf("irq_level=%d next_delay=%f\n",
 264            irq_level,
 265            (double)(expire_time - current_time) / NANOSECONDS_PER_SECOND);
 266 #endif
 267     s->next_transition_time = expire_time;
 268     if (expire_time != -1)
 269         timer_mod(s->irq_timer, expire_time);
 270     else
 271         timer_del(s->irq_timer);
 272 }
 273
 274 static void pit_irq_timer(void *opaque)
 275 {
 276     PITChannelState *s = opaque;
 277
 278     pit_irq_timer_update(s, s->next_transition_time);
 279 }
 280
 281 static void pit_reset(DeviceState *dev)
 282 {
 283     PITCommonState *pit = PIT_COMMON(dev);
 284     PITChannelState *s;
 285
 286     pit_reset_common(pit);
 287
 288     s = &pit->channels[0];
 289     if (!s->irq_disabled) {
 290         timer_mod(s->irq_timer, s->next_transition_time);
 291     }
 292 }
 293
 294 /* When HPET is operating in legacy mode, suppress the ignored timer IRQ,
 295  * reenable it when legacy mode is left again. */
 296 static void pit_irq_control(void *opaque, int n, int enable)
 297 {
 298     PITCommonState *pit = opaque;
 299     PITChannelState *s = &pit->channels[0];
 300
 301     if (enable) {
 302         s->irq_disabled = 0;
 303         pit_irq_timer_update(s, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
 304     } else {
 305         s->irq_disabled = 1;
 306         timer_del(s->irq_timer);
 307     }
 308 }
 309
 310 static const MemoryRegionOps pit_ioport_ops = {
 311     .read = pit_ioport_read,
 312     .write = pit_ioport_write,
 313     .impl = {
 314         .min_access_size = 1,
 315         .max_access_size = 1,
 316     },
 317     .endianness = DEVICE_LITTLE_ENDIAN,
 318 };
 319
 320 static void pit_post_load(PITCommonState *s)
 321 {
 322     PITChannelState *sc = &s->channels[0];
 323
 324     if (sc->next_transition_time != -1) {
 325         timer_mod(sc->irq_timer, sc->next_transition_time);
 326     } else {
 327         timer_del(sc->irq_timer);
 328     }
 329 }
 330
 331 static void pit_realizefn(DeviceState *dev, Error **errp)
 332 {
 333     PITCommonState *pit = PIT_COMMON(dev);
 334     PITClass *pc = PIT_GET_CLASS(dev);
 335     PITChannelState *s;
 336
 337     s = &pit->channels[0];
 338     /* the timer 0 is connected to an IRQ */
 339     s->irq_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pit_irq_timer, s);
 340     qdev_init_gpio_out(dev, &s->irq, 1);
 341
 342     memory_region_init_io(&pit->ioports, OBJECT(pit), &pit_ioport_ops,
 343                           pit, "pit", 4);
 344
 345     qdev_init_gpio_in(dev, pit_irq_control, 1);
 346
 347     pc->parent_realize(dev, errp);
 348 }
 349
 350 static Property pit_properties[] = {
 351     DEFINE_PROP_UINT32("iobase", PITCommonState, iobase,  -1),
 352     DEFINE_PROP_END_OF_LIST(),
 353 };
 354
 355 static void pit_class_initfn(ObjectClass *klass, void *data)
 356 {
 357     PITClass *pc = PIT_CLASS(klass);
 358     PITCommonClass *k = PIT_COMMON_CLASS(klass);
 359     DeviceClass *dc = DEVICE_CLASS(klass);
 360
 361     device_class_set_parent_realize(dc, pit_realizefn, &pc->parent_realize);
 362     k->set_channel_gate = pit_set_channel_gate;
 363     k->get_channel_info = pit_get_channel_info_common;
 364     k->post_load = pit_post_load;
 365     dc->reset = pit_reset;
 366     dc->props = pit_properties;
 367 }
 368
 369 static const TypeInfo pit_info = {
 370     .name          = TYPE_I8254,
 371     .parent        = TYPE_PIT_COMMON,
 372     .instance_size = sizeof(PITCommonState),
 373     .class_init    = pit_class_initfn,
 374     .class_size    = sizeof(PITClass),
 375 };
 376
 377 static void pit_register_types(void)
 378 {
 379     type_register_static(&pit_info);
 380 }
 381
 382 type_init(pit_register_types)