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