xref: /qemu/hw/timer/hpet.c (revision db1015e92e04835c9eb50c29625fe566d1202dbd)
1 /*
2  *  High Precision Event Timer emulation
3  *
4  *  Copyright (c) 2007 Alexander Graf
5  *  Copyright (c) 2008 IBM Corporation
6  *
7  *  Authors: Beth Kon <bkon@us.ibm.com>
8  *
9  * This library is free software; you can redistribute it and/or
10  * modify it under the terms of the GNU Lesser General Public
11  * License as published by the Free Software Foundation; either
12  * version 2 of the License, or (at your option) any later version.
13  *
14  * This library is distributed in the hope that it will be useful,
15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
17  * Lesser General Public License for more details.
18  *
19  * You should have received a copy of the GNU Lesser General Public
20  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
21  *
22  * *****************************************************************
23  *
24  * This driver attempts to emulate an HPET device in software.
25  */
26 
27 #include "qemu/osdep.h"
28 #include "hw/i386/pc.h"
29 #include "hw/irq.h"
30 #include "qapi/error.h"
31 #include "qemu/error-report.h"
32 #include "qemu/timer.h"
33 #include "hw/timer/hpet.h"
34 #include "hw/sysbus.h"
35 #include "hw/rtc/mc146818rtc.h"
36 #include "hw/rtc/mc146818rtc_regs.h"
37 #include "migration/vmstate.h"
38 #include "hw/timer/i8254.h"
39 #include "exec/address-spaces.h"
40 #include "qom/object.h"
41 
42 //#define HPET_DEBUG
43 #ifdef HPET_DEBUG
44 #define DPRINTF printf
45 #else
46 #define DPRINTF(...)
47 #endif
48 
49 #define HPET_MSI_SUPPORT        0
50 
51 typedef struct HPETState HPETState;
52 #define HPET(obj) OBJECT_CHECK(HPETState, (obj), TYPE_HPET)
53 
54 struct HPETState;
55 typedef struct HPETTimer {  /* timers */
56     uint8_t tn;             /*timer number*/
57     QEMUTimer *qemu_timer;
58     struct HPETState *state;
59     /* Memory-mapped, software visible timer registers */
60     uint64_t config;        /* configuration/cap */
61     uint64_t cmp;           /* comparator */
62     uint64_t fsb;           /* FSB route */
63     /* Hidden register state */
64     uint64_t period;        /* Last value written to comparator */
65     uint8_t wrap_flag;      /* timer pop will indicate wrap for one-shot 32-bit
66                              * mode. Next pop will be actual timer expiration.
67                              */
68 } HPETTimer;
69 
70 struct HPETState {
71     /*< private >*/
72     SysBusDevice parent_obj;
73     /*< public >*/
74 
75     MemoryRegion iomem;
76     uint64_t hpet_offset;
77     bool hpet_offset_saved;
78     qemu_irq irqs[HPET_NUM_IRQ_ROUTES];
79     uint32_t flags;
80     uint8_t rtc_irq_level;
81     qemu_irq pit_enabled;
82     uint8_t num_timers;
83     uint32_t intcap;
84     HPETTimer timer[HPET_MAX_TIMERS];
85 
86     /* Memory-mapped, software visible registers */
87     uint64_t capability;        /* capabilities */
88     uint64_t config;            /* configuration */
89     uint64_t isr;               /* interrupt status reg */
90     uint64_t hpet_counter;      /* main counter */
91     uint8_t  hpet_id;           /* instance id */
92 };
93 
94 static uint32_t hpet_in_legacy_mode(HPETState *s)
95 {
96     return s->config & HPET_CFG_LEGACY;
97 }
98 
99 static uint32_t timer_int_route(struct HPETTimer *timer)
100 {
101     return (timer->config & HPET_TN_INT_ROUTE_MASK) >> HPET_TN_INT_ROUTE_SHIFT;
102 }
103 
104 static uint32_t timer_fsb_route(HPETTimer *t)
105 {
106     return t->config & HPET_TN_FSB_ENABLE;
107 }
108 
109 static uint32_t hpet_enabled(HPETState *s)
110 {
111     return s->config & HPET_CFG_ENABLE;
112 }
113 
114 static uint32_t timer_is_periodic(HPETTimer *t)
115 {
116     return t->config & HPET_TN_PERIODIC;
117 }
118 
119 static uint32_t timer_enabled(HPETTimer *t)
120 {
121     return t->config & HPET_TN_ENABLE;
122 }
123 
124 static uint32_t hpet_time_after(uint64_t a, uint64_t b)
125 {
126     return ((int32_t)(b - a) < 0);
127 }
128 
129 static uint32_t hpet_time_after64(uint64_t a, uint64_t b)
130 {
131     return ((int64_t)(b - a) < 0);
132 }
133 
134 static uint64_t ticks_to_ns(uint64_t value)
135 {
136     return value * HPET_CLK_PERIOD;
137 }
138 
139 static uint64_t ns_to_ticks(uint64_t value)
140 {
141     return value / HPET_CLK_PERIOD;
142 }
143 
144 static uint64_t hpet_fixup_reg(uint64_t new, uint64_t old, uint64_t mask)
145 {
146     new &= mask;
147     new |= old & ~mask;
148     return new;
149 }
150 
151 static int activating_bit(uint64_t old, uint64_t new, uint64_t mask)
152 {
153     return (!(old & mask) && (new & mask));
154 }
155 
156 static int deactivating_bit(uint64_t old, uint64_t new, uint64_t mask)
157 {
158     return ((old & mask) && !(new & mask));
159 }
160 
161 static uint64_t hpet_get_ticks(HPETState *s)
162 {
163     return ns_to_ticks(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->hpet_offset);
164 }
165 
166 /*
167  * calculate diff between comparator value and current ticks
168  */
169 static inline uint64_t hpet_calculate_diff(HPETTimer *t, uint64_t current)
170 {
171 
172     if (t->config & HPET_TN_32BIT) {
173         uint32_t diff, cmp;
174 
175         cmp = (uint32_t)t->cmp;
176         diff = cmp - (uint32_t)current;
177         diff = (int32_t)diff > 0 ? diff : (uint32_t)1;
178         return (uint64_t)diff;
179     } else {
180         uint64_t diff, cmp;
181 
182         cmp = t->cmp;
183         diff = cmp - current;
184         diff = (int64_t)diff > 0 ? diff : (uint64_t)1;
185         return diff;
186     }
187 }
188 
189 static void update_irq(struct HPETTimer *timer, int set)
190 {
191     uint64_t mask;
192     HPETState *s;
193     int route;
194 
195     if (timer->tn <= 1 && hpet_in_legacy_mode(timer->state)) {
196         /* if LegacyReplacementRoute bit is set, HPET specification requires
197          * timer0 be routed to IRQ0 in NON-APIC or IRQ2 in the I/O APIC,
198          * timer1 be routed to IRQ8 in NON-APIC or IRQ8 in the I/O APIC.
199          */
200         route = (timer->tn == 0) ? 0 : RTC_ISA_IRQ;
201     } else {
202         route = timer_int_route(timer);
203     }
204     s = timer->state;
205     mask = 1 << timer->tn;
206     if (!set || !timer_enabled(timer) || !hpet_enabled(timer->state)) {
207         s->isr &= ~mask;
208         if (!timer_fsb_route(timer)) {
209             qemu_irq_lower(s->irqs[route]);
210         }
211     } else if (timer_fsb_route(timer)) {
212         address_space_stl_le(&address_space_memory, timer->fsb >> 32,
213                              timer->fsb & 0xffffffff, MEMTXATTRS_UNSPECIFIED,
214                              NULL);
215     } else if (timer->config & HPET_TN_TYPE_LEVEL) {
216         s->isr |= mask;
217         qemu_irq_raise(s->irqs[route]);
218     } else {
219         s->isr &= ~mask;
220         qemu_irq_pulse(s->irqs[route]);
221     }
222 }
223 
224 static int hpet_pre_save(void *opaque)
225 {
226     HPETState *s = opaque;
227 
228     /* save current counter value */
229     if (hpet_enabled(s)) {
230         s->hpet_counter = hpet_get_ticks(s);
231     }
232 
233     return 0;
234 }
235 
236 static int hpet_pre_load(void *opaque)
237 {
238     HPETState *s = opaque;
239 
240     /* version 1 only supports 3, later versions will load the actual value */
241     s->num_timers = HPET_MIN_TIMERS;
242     return 0;
243 }
244 
245 static bool hpet_validate_num_timers(void *opaque, int version_id)
246 {
247     HPETState *s = opaque;
248 
249     if (s->num_timers < HPET_MIN_TIMERS) {
250         return false;
251     } else if (s->num_timers > HPET_MAX_TIMERS) {
252         return false;
253     }
254     return true;
255 }
256 
257 static int hpet_post_load(void *opaque, int version_id)
258 {
259     HPETState *s = opaque;
260 
261     /* Recalculate the offset between the main counter and guest time */
262     if (!s->hpet_offset_saved) {
263         s->hpet_offset = ticks_to_ns(s->hpet_counter)
264                         - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
265     }
266 
267     /* Push number of timers into capability returned via HPET_ID */
268     s->capability &= ~HPET_ID_NUM_TIM_MASK;
269     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
270     hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
271 
272     /* Derive HPET_MSI_SUPPORT from the capability of the first timer. */
273     s->flags &= ~(1 << HPET_MSI_SUPPORT);
274     if (s->timer[0].config & HPET_TN_FSB_CAP) {
275         s->flags |= 1 << HPET_MSI_SUPPORT;
276     }
277     return 0;
278 }
279 
280 static bool hpet_offset_needed(void *opaque)
281 {
282     HPETState *s = opaque;
283 
284     return hpet_enabled(s) && s->hpet_offset_saved;
285 }
286 
287 static bool hpet_rtc_irq_level_needed(void *opaque)
288 {
289     HPETState *s = opaque;
290 
291     return s->rtc_irq_level != 0;
292 }
293 
294 static const VMStateDescription vmstate_hpet_rtc_irq_level = {
295     .name = "hpet/rtc_irq_level",
296     .version_id = 1,
297     .minimum_version_id = 1,
298     .needed = hpet_rtc_irq_level_needed,
299     .fields = (VMStateField[]) {
300         VMSTATE_UINT8(rtc_irq_level, HPETState),
301         VMSTATE_END_OF_LIST()
302     }
303 };
304 
305 static const VMStateDescription vmstate_hpet_offset = {
306     .name = "hpet/offset",
307     .version_id = 1,
308     .minimum_version_id = 1,
309     .needed = hpet_offset_needed,
310     .fields = (VMStateField[]) {
311         VMSTATE_UINT64(hpet_offset, HPETState),
312         VMSTATE_END_OF_LIST()
313     }
314 };
315 
316 static const VMStateDescription vmstate_hpet_timer = {
317     .name = "hpet_timer",
318     .version_id = 1,
319     .minimum_version_id = 1,
320     .fields = (VMStateField[]) {
321         VMSTATE_UINT8(tn, HPETTimer),
322         VMSTATE_UINT64(config, HPETTimer),
323         VMSTATE_UINT64(cmp, HPETTimer),
324         VMSTATE_UINT64(fsb, HPETTimer),
325         VMSTATE_UINT64(period, HPETTimer),
326         VMSTATE_UINT8(wrap_flag, HPETTimer),
327         VMSTATE_TIMER_PTR(qemu_timer, HPETTimer),
328         VMSTATE_END_OF_LIST()
329     }
330 };
331 
332 static const VMStateDescription vmstate_hpet = {
333     .name = "hpet",
334     .version_id = 2,
335     .minimum_version_id = 1,
336     .pre_save = hpet_pre_save,
337     .pre_load = hpet_pre_load,
338     .post_load = hpet_post_load,
339     .fields = (VMStateField[]) {
340         VMSTATE_UINT64(config, HPETState),
341         VMSTATE_UINT64(isr, HPETState),
342         VMSTATE_UINT64(hpet_counter, HPETState),
343         VMSTATE_UINT8_V(num_timers, HPETState, 2),
344         VMSTATE_VALIDATE("num_timers in range", hpet_validate_num_timers),
345         VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
346                                     vmstate_hpet_timer, HPETTimer),
347         VMSTATE_END_OF_LIST()
348     },
349     .subsections = (const VMStateDescription*[]) {
350         &vmstate_hpet_rtc_irq_level,
351         &vmstate_hpet_offset,
352         NULL
353     }
354 };
355 
356 /*
357  * timer expiration callback
358  */
359 static void hpet_timer(void *opaque)
360 {
361     HPETTimer *t = opaque;
362     uint64_t diff;
363 
364     uint64_t period = t->period;
365     uint64_t cur_tick = hpet_get_ticks(t->state);
366 
367     if (timer_is_periodic(t) && period != 0) {
368         if (t->config & HPET_TN_32BIT) {
369             while (hpet_time_after(cur_tick, t->cmp)) {
370                 t->cmp = (uint32_t)(t->cmp + t->period);
371             }
372         } else {
373             while (hpet_time_after64(cur_tick, t->cmp)) {
374                 t->cmp += period;
375             }
376         }
377         diff = hpet_calculate_diff(t, cur_tick);
378         timer_mod(t->qemu_timer,
379                        qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + (int64_t)ticks_to_ns(diff));
380     } else if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
381         if (t->wrap_flag) {
382             diff = hpet_calculate_diff(t, cur_tick);
383             timer_mod(t->qemu_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
384                            (int64_t)ticks_to_ns(diff));
385             t->wrap_flag = 0;
386         }
387     }
388     update_irq(t, 1);
389 }
390 
391 static void hpet_set_timer(HPETTimer *t)
392 {
393     uint64_t diff;
394     uint32_t wrap_diff;  /* how many ticks until we wrap? */
395     uint64_t cur_tick = hpet_get_ticks(t->state);
396 
397     /* whenever new timer is being set up, make sure wrap_flag is 0 */
398     t->wrap_flag = 0;
399     diff = hpet_calculate_diff(t, cur_tick);
400 
401     /* hpet spec says in one-shot 32-bit mode, generate an interrupt when
402      * counter wraps in addition to an interrupt with comparator match.
403      */
404     if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
405         wrap_diff = 0xffffffff - (uint32_t)cur_tick;
406         if (wrap_diff < (uint32_t)diff) {
407             diff = wrap_diff;
408             t->wrap_flag = 1;
409         }
410     }
411     timer_mod(t->qemu_timer,
412                    qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + (int64_t)ticks_to_ns(diff));
413 }
414 
415 static void hpet_del_timer(HPETTimer *t)
416 {
417     timer_del(t->qemu_timer);
418     update_irq(t, 0);
419 }
420 
421 #ifdef HPET_DEBUG
422 static uint32_t hpet_ram_readb(void *opaque, hwaddr addr)
423 {
424     printf("qemu: hpet_read b at %" PRIx64 "\n", addr);
425     return 0;
426 }
427 
428 static uint32_t hpet_ram_readw(void *opaque, hwaddr addr)
429 {
430     printf("qemu: hpet_read w at %" PRIx64 "\n", addr);
431     return 0;
432 }
433 #endif
434 
435 static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
436                               unsigned size)
437 {
438     HPETState *s = opaque;
439     uint64_t cur_tick, index;
440 
441     DPRINTF("qemu: Enter hpet_ram_readl at %" PRIx64 "\n", addr);
442     index = addr;
443     /*address range of all TN regs*/
444     if (index >= 0x100 && index <= 0x3ff) {
445         uint8_t timer_id = (addr - 0x100) / 0x20;
446         HPETTimer *timer = &s->timer[timer_id];
447 
448         if (timer_id > s->num_timers) {
449             DPRINTF("qemu: timer id out of range\n");
450             return 0;
451         }
452 
453         switch ((addr - 0x100) % 0x20) {
454         case HPET_TN_CFG:
455             return timer->config;
456         case HPET_TN_CFG + 4: // Interrupt capabilities
457             return timer->config >> 32;
458         case HPET_TN_CMP: // comparator register
459             return timer->cmp;
460         case HPET_TN_CMP + 4:
461             return timer->cmp >> 32;
462         case HPET_TN_ROUTE:
463             return timer->fsb;
464         case HPET_TN_ROUTE + 4:
465             return timer->fsb >> 32;
466         default:
467             DPRINTF("qemu: invalid hpet_ram_readl\n");
468             break;
469         }
470     } else {
471         switch (index) {
472         case HPET_ID:
473             return s->capability;
474         case HPET_PERIOD:
475             return s->capability >> 32;
476         case HPET_CFG:
477             return s->config;
478         case HPET_CFG + 4:
479             DPRINTF("qemu: invalid HPET_CFG + 4 hpet_ram_readl\n");
480             return 0;
481         case HPET_COUNTER:
482             if (hpet_enabled(s)) {
483                 cur_tick = hpet_get_ticks(s);
484             } else {
485                 cur_tick = s->hpet_counter;
486             }
487             DPRINTF("qemu: reading counter  = %" PRIx64 "\n", cur_tick);
488             return cur_tick;
489         case HPET_COUNTER + 4:
490             if (hpet_enabled(s)) {
491                 cur_tick = hpet_get_ticks(s);
492             } else {
493                 cur_tick = s->hpet_counter;
494             }
495             DPRINTF("qemu: reading counter + 4  = %" PRIx64 "\n", cur_tick);
496             return cur_tick >> 32;
497         case HPET_STATUS:
498             return s->isr;
499         default:
500             DPRINTF("qemu: invalid hpet_ram_readl\n");
501             break;
502         }
503     }
504     return 0;
505 }
506 
507 static void hpet_ram_write(void *opaque, hwaddr addr,
508                            uint64_t value, unsigned size)
509 {
510     int i;
511     HPETState *s = opaque;
512     uint64_t old_val, new_val, val, index;
513 
514     DPRINTF("qemu: Enter hpet_ram_writel at %" PRIx64 " = %#x\n", addr, value);
515     index = addr;
516     old_val = hpet_ram_read(opaque, addr, 4);
517     new_val = value;
518 
519     /*address range of all TN regs*/
520     if (index >= 0x100 && index <= 0x3ff) {
521         uint8_t timer_id = (addr - 0x100) / 0x20;
522         HPETTimer *timer = &s->timer[timer_id];
523 
524         DPRINTF("qemu: hpet_ram_writel timer_id = %#x\n", timer_id);
525         if (timer_id > s->num_timers) {
526             DPRINTF("qemu: timer id out of range\n");
527             return;
528         }
529         switch ((addr - 0x100) % 0x20) {
530         case HPET_TN_CFG:
531             DPRINTF("qemu: hpet_ram_writel HPET_TN_CFG\n");
532             if (activating_bit(old_val, new_val, HPET_TN_FSB_ENABLE)) {
533                 update_irq(timer, 0);
534             }
535             val = hpet_fixup_reg(new_val, old_val, HPET_TN_CFG_WRITE_MASK);
536             timer->config = (timer->config & 0xffffffff00000000ULL) | val;
537             if (new_val & HPET_TN_32BIT) {
538                 timer->cmp = (uint32_t)timer->cmp;
539                 timer->period = (uint32_t)timer->period;
540             }
541             if (activating_bit(old_val, new_val, HPET_TN_ENABLE) &&
542                 hpet_enabled(s)) {
543                 hpet_set_timer(timer);
544             } else if (deactivating_bit(old_val, new_val, HPET_TN_ENABLE)) {
545                 hpet_del_timer(timer);
546             }
547             break;
548         case HPET_TN_CFG + 4: // Interrupt capabilities
549             DPRINTF("qemu: invalid HPET_TN_CFG+4 write\n");
550             break;
551         case HPET_TN_CMP: // comparator register
552             DPRINTF("qemu: hpet_ram_writel HPET_TN_CMP\n");
553             if (timer->config & HPET_TN_32BIT) {
554                 new_val = (uint32_t)new_val;
555             }
556             if (!timer_is_periodic(timer)
557                 || (timer->config & HPET_TN_SETVAL)) {
558                 timer->cmp = (timer->cmp & 0xffffffff00000000ULL) | new_val;
559             }
560             if (timer_is_periodic(timer)) {
561                 /*
562                  * FIXME: Clamp period to reasonable min value?
563                  * Clamp period to reasonable max value
564                  */
565                 new_val &= (timer->config & HPET_TN_32BIT ? ~0u : ~0ull) >> 1;
566                 timer->period =
567                     (timer->period & 0xffffffff00000000ULL) | new_val;
568             }
569             timer->config &= ~HPET_TN_SETVAL;
570             if (hpet_enabled(s)) {
571                 hpet_set_timer(timer);
572             }
573             break;
574         case HPET_TN_CMP + 4: // comparator register high order
575             DPRINTF("qemu: hpet_ram_writel HPET_TN_CMP + 4\n");
576             if (!timer_is_periodic(timer)
577                 || (timer->config & HPET_TN_SETVAL)) {
578                 timer->cmp = (timer->cmp & 0xffffffffULL) | new_val << 32;
579             } else {
580                 /*
581                  * FIXME: Clamp period to reasonable min value?
582                  * Clamp period to reasonable max value
583                  */
584                 new_val &= (timer->config & HPET_TN_32BIT ? ~0u : ~0ull) >> 1;
585                 timer->period =
586                     (timer->period & 0xffffffffULL) | new_val << 32;
587                 }
588                 timer->config &= ~HPET_TN_SETVAL;
589                 if (hpet_enabled(s)) {
590                     hpet_set_timer(timer);
591                 }
592                 break;
593         case HPET_TN_ROUTE:
594             timer->fsb = (timer->fsb & 0xffffffff00000000ULL) | new_val;
595             break;
596         case HPET_TN_ROUTE + 4:
597             timer->fsb = (new_val << 32) | (timer->fsb & 0xffffffff);
598             break;
599         default:
600             DPRINTF("qemu: invalid hpet_ram_writel\n");
601             break;
602         }
603         return;
604     } else {
605         switch (index) {
606         case HPET_ID:
607             return;
608         case HPET_CFG:
609             val = hpet_fixup_reg(new_val, old_val, HPET_CFG_WRITE_MASK);
610             s->config = (s->config & 0xffffffff00000000ULL) | val;
611             if (activating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
612                 /* Enable main counter and interrupt generation. */
613                 s->hpet_offset =
614                     ticks_to_ns(s->hpet_counter) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
615                 for (i = 0; i < s->num_timers; i++) {
616                     if ((&s->timer[i])->cmp != ~0ULL) {
617                         hpet_set_timer(&s->timer[i]);
618                     }
619                 }
620             } else if (deactivating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
621                 /* Halt main counter and disable interrupt generation. */
622                 s->hpet_counter = hpet_get_ticks(s);
623                 for (i = 0; i < s->num_timers; i++) {
624                     hpet_del_timer(&s->timer[i]);
625                 }
626             }
627             /* i8254 and RTC output pins are disabled
628              * when HPET is in legacy mode */
629             if (activating_bit(old_val, new_val, HPET_CFG_LEGACY)) {
630                 qemu_set_irq(s->pit_enabled, 0);
631                 qemu_irq_lower(s->irqs[0]);
632                 qemu_irq_lower(s->irqs[RTC_ISA_IRQ]);
633             } else if (deactivating_bit(old_val, new_val, HPET_CFG_LEGACY)) {
634                 qemu_irq_lower(s->irqs[0]);
635                 qemu_set_irq(s->pit_enabled, 1);
636                 qemu_set_irq(s->irqs[RTC_ISA_IRQ], s->rtc_irq_level);
637             }
638             break;
639         case HPET_CFG + 4:
640             DPRINTF("qemu: invalid HPET_CFG+4 write\n");
641             break;
642         case HPET_STATUS:
643             val = new_val & s->isr;
644             for (i = 0; i < s->num_timers; i++) {
645                 if (val & (1 << i)) {
646                     update_irq(&s->timer[i], 0);
647                 }
648             }
649             break;
650         case HPET_COUNTER:
651             if (hpet_enabled(s)) {
652                 DPRINTF("qemu: Writing counter while HPET enabled!\n");
653             }
654             s->hpet_counter =
655                 (s->hpet_counter & 0xffffffff00000000ULL) | value;
656             DPRINTF("qemu: HPET counter written. ctr = %#x -> %" PRIx64 "\n",
657                     value, s->hpet_counter);
658             break;
659         case HPET_COUNTER + 4:
660             if (hpet_enabled(s)) {
661                 DPRINTF("qemu: Writing counter while HPET enabled!\n");
662             }
663             s->hpet_counter =
664                 (s->hpet_counter & 0xffffffffULL) | (((uint64_t)value) << 32);
665             DPRINTF("qemu: HPET counter + 4 written. ctr = %#x -> %" PRIx64 "\n",
666                     value, s->hpet_counter);
667             break;
668         default:
669             DPRINTF("qemu: invalid hpet_ram_writel\n");
670             break;
671         }
672     }
673 }
674 
675 static const MemoryRegionOps hpet_ram_ops = {
676     .read = hpet_ram_read,
677     .write = hpet_ram_write,
678     .valid = {
679         .min_access_size = 4,
680         .max_access_size = 4,
681     },
682     .endianness = DEVICE_NATIVE_ENDIAN,
683 };
684 
685 static void hpet_reset(DeviceState *d)
686 {
687     HPETState *s = HPET(d);
688     SysBusDevice *sbd = SYS_BUS_DEVICE(d);
689     int i;
690 
691     for (i = 0; i < s->num_timers; i++) {
692         HPETTimer *timer = &s->timer[i];
693 
694         hpet_del_timer(timer);
695         timer->cmp = ~0ULL;
696         timer->config = HPET_TN_PERIODIC_CAP | HPET_TN_SIZE_CAP;
697         if (s->flags & (1 << HPET_MSI_SUPPORT)) {
698             timer->config |= HPET_TN_FSB_CAP;
699         }
700         /* advertise availability of ioapic int */
701         timer->config |=  (uint64_t)s->intcap << 32;
702         timer->period = 0ULL;
703         timer->wrap_flag = 0;
704     }
705 
706     qemu_set_irq(s->pit_enabled, 1);
707     s->hpet_counter = 0ULL;
708     s->hpet_offset = 0ULL;
709     s->config = 0ULL;
710     hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
711     hpet_cfg.hpet[s->hpet_id].address = sbd->mmio[0].addr;
712 
713     /* to document that the RTC lowers its output on reset as well */
714     s->rtc_irq_level = 0;
715 }
716 
717 static void hpet_handle_legacy_irq(void *opaque, int n, int level)
718 {
719     HPETState *s = HPET(opaque);
720 
721     if (n == HPET_LEGACY_PIT_INT) {
722         if (!hpet_in_legacy_mode(s)) {
723             qemu_set_irq(s->irqs[0], level);
724         }
725     } else {
726         s->rtc_irq_level = level;
727         if (!hpet_in_legacy_mode(s)) {
728             qemu_set_irq(s->irqs[RTC_ISA_IRQ], level);
729         }
730     }
731 }
732 
733 static void hpet_init(Object *obj)
734 {
735     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
736     HPETState *s = HPET(obj);
737 
738     /* HPET Area */
739     memory_region_init_io(&s->iomem, obj, &hpet_ram_ops, s, "hpet", HPET_LEN);
740     sysbus_init_mmio(sbd, &s->iomem);
741 }
742 
743 static void hpet_realize(DeviceState *dev, Error **errp)
744 {
745     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
746     HPETState *s = HPET(dev);
747     int i;
748     HPETTimer *timer;
749 
750     if (!s->intcap) {
751         warn_report("Hpet's intcap not initialized");
752     }
753     if (hpet_cfg.count == UINT8_MAX) {
754         /* first instance */
755         hpet_cfg.count = 0;
756     }
757 
758     if (hpet_cfg.count == 8) {
759         error_setg(errp, "Only 8 instances of HPET is allowed");
760         return;
761     }
762 
763     s->hpet_id = hpet_cfg.count++;
764 
765     for (i = 0; i < HPET_NUM_IRQ_ROUTES; i++) {
766         sysbus_init_irq(sbd, &s->irqs[i]);
767     }
768 
769     if (s->num_timers < HPET_MIN_TIMERS) {
770         s->num_timers = HPET_MIN_TIMERS;
771     } else if (s->num_timers > HPET_MAX_TIMERS) {
772         s->num_timers = HPET_MAX_TIMERS;
773     }
774     for (i = 0; i < HPET_MAX_TIMERS; i++) {
775         timer = &s->timer[i];
776         timer->qemu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, hpet_timer, timer);
777         timer->tn = i;
778         timer->state = s;
779     }
780 
781     /* 64-bit main counter; LegacyReplacementRoute. */
782     s->capability = 0x8086a001ULL;
783     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
784     s->capability |= ((uint64_t)(HPET_CLK_PERIOD * FS_PER_NS) << 32);
785 
786     qdev_init_gpio_in(dev, hpet_handle_legacy_irq, 2);
787     qdev_init_gpio_out(dev, &s->pit_enabled, 1);
788 }
789 
790 static Property hpet_device_properties[] = {
791     DEFINE_PROP_UINT8("timers", HPETState, num_timers, HPET_MIN_TIMERS),
792     DEFINE_PROP_BIT("msi", HPETState, flags, HPET_MSI_SUPPORT, false),
793     DEFINE_PROP_UINT32(HPET_INTCAP, HPETState, intcap, 0),
794     DEFINE_PROP_BOOL("hpet-offset-saved", HPETState, hpet_offset_saved, true),
795     DEFINE_PROP_END_OF_LIST(),
796 };
797 
798 static void hpet_device_class_init(ObjectClass *klass, void *data)
799 {
800     DeviceClass *dc = DEVICE_CLASS(klass);
801 
802     dc->realize = hpet_realize;
803     dc->reset = hpet_reset;
804     dc->vmsd = &vmstate_hpet;
805     device_class_set_props(dc, hpet_device_properties);
806 }
807 
808 static const TypeInfo hpet_device_info = {
809     .name          = TYPE_HPET,
810     .parent        = TYPE_SYS_BUS_DEVICE,
811     .instance_size = sizeof(HPETState),
812     .instance_init = hpet_init,
813     .class_init    = hpet_device_class_init,
814 };
815 
816 static void hpet_register_types(void)
817 {
818     type_register_static(&hpet_device_info);
819 }
820 
821 type_init(hpet_register_types)
822