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