i8254.c (10906B)
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#include "qom/object.h" 32 33//#define DEBUG_PIT 34 35#define RW_STATE_LSB 1 36#define RW_STATE_MSB 2 37#define RW_STATE_WORD0 3 38#define RW_STATE_WORD1 4 39 40typedef struct PITClass PITClass; 41DECLARE_CLASS_CHECKERS(PITClass, PIT, 42 TYPE_I8254) 43 44struct PITClass { 45 PITCommonClass parent_class; 46 47 DeviceRealize parent_realize; 48}; 49 50static void pit_irq_timer_update(PITChannelState *s, int64_t current_time); 51 52static int pit_get_count(PITChannelState *s) 53{ 54 uint64_t d; 55 int counter; 56 57 d = muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) - s->count_load_time, PIT_FREQ, 58 NANOSECONDS_PER_SECOND); 59 switch(s->mode) { 60 case 0: 61 case 1: 62 case 4: 63 case 5: 64 counter = (s->count - d) & 0xffff; 65 break; 66 case 3: 67 /* XXX: may be incorrect for odd counts */ 68 counter = s->count - ((2 * d) % s->count); 69 break; 70 default: 71 counter = s->count - (d % s->count); 72 break; 73 } 74 return counter; 75} 76 77/* val must be 0 or 1 */ 78static void pit_set_channel_gate(PITCommonState *s, PITChannelState *sc, 79 int val) 80{ 81 switch (sc->mode) { 82 default: 83 case 0: 84 case 4: 85 /* XXX: just disable/enable counting */ 86 break; 87 case 1: 88 case 5: 89 if (sc->gate < val) { 90 /* restart counting on rising edge */ 91 sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); 92 pit_irq_timer_update(sc, sc->count_load_time); 93 } 94 break; 95 case 2: 96 case 3: 97 if (sc->gate < val) { 98 /* restart counting on rising edge */ 99 sc->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); 100 pit_irq_timer_update(sc, sc->count_load_time); 101 } 102 /* XXX: disable/enable counting */ 103 break; 104 } 105 sc->gate = val; 106} 107 108static inline void pit_load_count(PITChannelState *s, int val) 109{ 110 if (val == 0) 111 val = 0x10000; 112 s->count_load_time = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL); 113 s->count = val; 114 pit_irq_timer_update(s, s->count_load_time); 115} 116 117/* if already latched, do not latch again */ 118static void pit_latch_count(PITChannelState *s) 119{ 120 if (!s->count_latched) { 121 s->latched_count = pit_get_count(s); 122 s->count_latched = s->rw_mode; 123 } 124} 125 126static void pit_ioport_write(void *opaque, hwaddr addr, 127 uint64_t val, unsigned size) 128{ 129 PITCommonState *pit = opaque; 130 int channel, access; 131 PITChannelState *s; 132 133 addr &= 3; 134 if (addr == 3) { 135 channel = val >> 6; 136 if (channel == 3) { 137 /* read back command */ 138 for(channel = 0; channel < 3; channel++) { 139 s = &pit->channels[channel]; 140 if (val & (2 << channel)) { 141 if (!(val & 0x20)) { 142 pit_latch_count(s); 143 } 144 if (!(val & 0x10) && !s->status_latched) { 145 /* status latch */ 146 /* XXX: add BCD and null count */ 147 s->status = 148 (pit_get_out(s, 149 qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)) << 7) | 150 (s->rw_mode << 4) | 151 (s->mode << 1) | 152 s->bcd; 153 s->status_latched = 1; 154 } 155 } 156 } 157 } else { 158 s = &pit->channels[channel]; 159 access = (val >> 4) & 3; 160 if (access == 0) { 161 pit_latch_count(s); 162 } else { 163 s->rw_mode = access; 164 s->read_state = access; 165 s->write_state = access; 166 167 s->mode = (val >> 1) & 7; 168 s->bcd = val & 1; 169 /* XXX: update irq timer ? */ 170 } 171 } 172 } else { 173 s = &pit->channels[addr]; 174 switch(s->write_state) { 175 default: 176 case RW_STATE_LSB: 177 pit_load_count(s, val); 178 break; 179 case RW_STATE_MSB: 180 pit_load_count(s, val << 8); 181 break; 182 case RW_STATE_WORD0: 183 s->write_latch = val; 184 s->write_state = RW_STATE_WORD1; 185 break; 186 case RW_STATE_WORD1: 187 pit_load_count(s, s->write_latch | (val << 8)); 188 s->write_state = RW_STATE_WORD0; 189 break; 190 } 191 } 192} 193 194static uint64_t pit_ioport_read(void *opaque, hwaddr addr, 195 unsigned size) 196{ 197 PITCommonState *pit = opaque; 198 int ret, count; 199 PITChannelState *s; 200 201 addr &= 3; 202 203 if (addr == 3) { 204 /* Mode/Command register is write only, read is ignored */ 205 return 0; 206 } 207 208 s = &pit->channels[addr]; 209 if (s->status_latched) { 210 s->status_latched = 0; 211 ret = s->status; 212 } else if (s->count_latched) { 213 switch(s->count_latched) { 214 default: 215 case RW_STATE_LSB: 216 ret = s->latched_count & 0xff; 217 s->count_latched = 0; 218 break; 219 case RW_STATE_MSB: 220 ret = s->latched_count >> 8; 221 s->count_latched = 0; 222 break; 223 case RW_STATE_WORD0: 224 ret = s->latched_count & 0xff; 225 s->count_latched = RW_STATE_MSB; 226 break; 227 } 228 } else { 229 switch(s->read_state) { 230 default: 231 case RW_STATE_LSB: 232 count = pit_get_count(s); 233 ret = count & 0xff; 234 break; 235 case RW_STATE_MSB: 236 count = pit_get_count(s); 237 ret = (count >> 8) & 0xff; 238 break; 239 case RW_STATE_WORD0: 240 count = pit_get_count(s); 241 ret = count & 0xff; 242 s->read_state = RW_STATE_WORD1; 243 break; 244 case RW_STATE_WORD1: 245 count = pit_get_count(s); 246 ret = (count >> 8) & 0xff; 247 s->read_state = RW_STATE_WORD0; 248 break; 249 } 250 } 251 return ret; 252} 253 254static void pit_irq_timer_update(PITChannelState *s, int64_t current_time) 255{ 256 int64_t expire_time; 257 int irq_level; 258 259 if (!s->irq_timer || s->irq_disabled) { 260 return; 261 } 262 expire_time = pit_get_next_transition_time(s, current_time); 263 irq_level = pit_get_out(s, current_time); 264 qemu_set_irq(s->irq, irq_level); 265#ifdef DEBUG_PIT 266 printf("irq_level=%d next_delay=%f\n", 267 irq_level, 268 (double)(expire_time - current_time) / NANOSECONDS_PER_SECOND); 269#endif 270 s->next_transition_time = expire_time; 271 if (expire_time != -1) 272 timer_mod(s->irq_timer, expire_time); 273 else 274 timer_del(s->irq_timer); 275} 276 277static void pit_irq_timer(void *opaque) 278{ 279 PITChannelState *s = opaque; 280 281 pit_irq_timer_update(s, s->next_transition_time); 282} 283 284static void pit_reset(DeviceState *dev) 285{ 286 PITCommonState *pit = PIT_COMMON(dev); 287 PITChannelState *s; 288 289 pit_reset_common(pit); 290 291 s = &pit->channels[0]; 292 if (!s->irq_disabled) { 293 timer_mod(s->irq_timer, s->next_transition_time); 294 } 295} 296 297/* When HPET is operating in legacy mode, suppress the ignored timer IRQ, 298 * reenable it when legacy mode is left again. */ 299static void pit_irq_control(void *opaque, int n, int enable) 300{ 301 PITCommonState *pit = opaque; 302 PITChannelState *s = &pit->channels[0]; 303 304 if (enable) { 305 s->irq_disabled = 0; 306 pit_irq_timer_update(s, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL)); 307 } else { 308 s->irq_disabled = 1; 309 timer_del(s->irq_timer); 310 } 311} 312 313static const MemoryRegionOps pit_ioport_ops = { 314 .read = pit_ioport_read, 315 .write = pit_ioport_write, 316 .impl = { 317 .min_access_size = 1, 318 .max_access_size = 1, 319 }, 320 .endianness = DEVICE_LITTLE_ENDIAN, 321}; 322 323static void pit_post_load(PITCommonState *s) 324{ 325 PITChannelState *sc = &s->channels[0]; 326 327 if (sc->next_transition_time != -1 && !sc->irq_disabled) { 328 timer_mod(sc->irq_timer, sc->next_transition_time); 329 } else { 330 timer_del(sc->irq_timer); 331 } 332} 333 334static void pit_realizefn(DeviceState *dev, Error **errp) 335{ 336 PITCommonState *pit = PIT_COMMON(dev); 337 PITClass *pc = PIT_GET_CLASS(dev); 338 PITChannelState *s; 339 340 s = &pit->channels[0]; 341 /* the timer 0 is connected to an IRQ */ 342 s->irq_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pit_irq_timer, s); 343 qdev_init_gpio_out(dev, &s->irq, 1); 344 345 memory_region_init_io(&pit->ioports, OBJECT(pit), &pit_ioport_ops, 346 pit, "pit", 4); 347 348 qdev_init_gpio_in(dev, pit_irq_control, 1); 349 350 pc->parent_realize(dev, errp); 351} 352 353static Property pit_properties[] = { 354 DEFINE_PROP_UINT32("iobase", PITCommonState, iobase, -1), 355 DEFINE_PROP_END_OF_LIST(), 356}; 357 358static void pit_class_initfn(ObjectClass *klass, void *data) 359{ 360 PITClass *pc = PIT_CLASS(klass); 361 PITCommonClass *k = PIT_COMMON_CLASS(klass); 362 DeviceClass *dc = DEVICE_CLASS(klass); 363 364 device_class_set_parent_realize(dc, pit_realizefn, &pc->parent_realize); 365 k->set_channel_gate = pit_set_channel_gate; 366 k->get_channel_info = pit_get_channel_info_common; 367 k->post_load = pit_post_load; 368 dc->reset = pit_reset; 369 device_class_set_props(dc, pit_properties); 370} 371 372static const TypeInfo pit_info = { 373 .name = TYPE_I8254, 374 .parent = TYPE_PIT_COMMON, 375 .instance_size = sizeof(PITCommonState), 376 .class_init = pit_class_initfn, 377 .class_size = sizeof(PITClass), 378}; 379 380static void pit_register_types(void) 381{ 382 type_register_static(&pit_info); 383} 384 385type_init(pit_register_types)