xref: /openbmc/qemu/hw/timer/hpet.c (revision 40d6ee94)
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/hw.h"
29 #include "hw/i386/pc.h"
30 #include "ui/console.h"
31 #include "qapi/error.h"
32 #include "qemu/error-report.h"
33 #include "qemu/timer.h"
34 #include "hw/timer/hpet.h"
35 #include "hw/sysbus.h"
36 #include "hw/timer/mc146818rtc.h"
37 #include "hw/timer/i8254.h"
38 
39 //#define HPET_DEBUG
40 #ifdef HPET_DEBUG
41 #define DPRINTF printf
42 #else
43 #define DPRINTF(...)
44 #endif
45 
46 #define HPET_MSI_SUPPORT        0
47 
48 #define HPET(obj) OBJECT_CHECK(HPETState, (obj), TYPE_HPET)
49 
50 struct HPETState;
51 typedef struct HPETTimer {  /* timers */
52     uint8_t tn;             /*timer number*/
53     QEMUTimer *qemu_timer;
54     struct HPETState *state;
55     /* Memory-mapped, software visible timer registers */
56     uint64_t config;        /* configuration/cap */
57     uint64_t cmp;           /* comparator */
58     uint64_t fsb;           /* FSB route */
59     /* Hidden register state */
60     uint64_t period;        /* Last value written to comparator */
61     uint8_t wrap_flag;      /* timer pop will indicate wrap for one-shot 32-bit
62                              * mode. Next pop will be actual timer expiration.
63                              */
64 } HPETTimer;
65 
66 typedef struct HPETState {
67     /*< private >*/
68     SysBusDevice parent_obj;
69     /*< public >*/
70 
71     MemoryRegion iomem;
72     uint64_t hpet_offset;
73     bool hpet_offset_saved;
74     qemu_irq irqs[HPET_NUM_IRQ_ROUTES];
75     uint32_t flags;
76     uint8_t rtc_irq_level;
77     qemu_irq pit_enabled;
78     uint8_t num_timers;
79     uint32_t intcap;
80     HPETTimer timer[HPET_MAX_TIMERS];
81 
82     /* Memory-mapped, software visible registers */
83     uint64_t capability;        /* capabilities */
84     uint64_t config;            /* configuration */
85     uint64_t isr;               /* interrupt status reg */
86     uint64_t hpet_counter;      /* main counter */
87     uint8_t  hpet_id;           /* instance id */
88 } HPETState;
89 
90 static uint32_t hpet_in_legacy_mode(HPETState *s)
91 {
92     return s->config & HPET_CFG_LEGACY;
93 }
94 
95 static uint32_t timer_int_route(struct HPETTimer *timer)
96 {
97     return (timer->config & HPET_TN_INT_ROUTE_MASK) >> HPET_TN_INT_ROUTE_SHIFT;
98 }
99 
100 static uint32_t timer_fsb_route(HPETTimer *t)
101 {
102     return t->config & HPET_TN_FSB_ENABLE;
103 }
104 
105 static uint32_t hpet_enabled(HPETState *s)
106 {
107     return s->config & HPET_CFG_ENABLE;
108 }
109 
110 static uint32_t timer_is_periodic(HPETTimer *t)
111 {
112     return t->config & HPET_TN_PERIODIC;
113 }
114 
115 static uint32_t timer_enabled(HPETTimer *t)
116 {
117     return t->config & HPET_TN_ENABLE;
118 }
119 
120 static uint32_t hpet_time_after(uint64_t a, uint64_t b)
121 {
122     return ((int32_t)(b - a) < 0);
123 }
124 
125 static uint32_t hpet_time_after64(uint64_t a, uint64_t b)
126 {
127     return ((int64_t)(b - a) < 0);
128 }
129 
130 static uint64_t ticks_to_ns(uint64_t value)
131 {
132     return value * HPET_CLK_PERIOD;
133 }
134 
135 static uint64_t ns_to_ticks(uint64_t value)
136 {
137     return value / HPET_CLK_PERIOD;
138 }
139 
140 static uint64_t hpet_fixup_reg(uint64_t new, uint64_t old, uint64_t mask)
141 {
142     new &= mask;
143     new |= old & ~mask;
144     return new;
145 }
146 
147 static int activating_bit(uint64_t old, uint64_t new, uint64_t mask)
148 {
149     return (!(old & mask) && (new & mask));
150 }
151 
152 static int deactivating_bit(uint64_t old, uint64_t new, uint64_t mask)
153 {
154     return ((old & mask) && !(new & mask));
155 }
156 
157 static uint64_t hpet_get_ticks(HPETState *s)
158 {
159     return ns_to_ticks(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + s->hpet_offset);
160 }
161 
162 /*
163  * calculate diff between comparator value and current ticks
164  */
165 static inline uint64_t hpet_calculate_diff(HPETTimer *t, uint64_t current)
166 {
167 
168     if (t->config & HPET_TN_32BIT) {
169         uint32_t diff, cmp;
170 
171         cmp = (uint32_t)t->cmp;
172         diff = cmp - (uint32_t)current;
173         diff = (int32_t)diff > 0 ? diff : (uint32_t)1;
174         return (uint64_t)diff;
175     } else {
176         uint64_t diff, cmp;
177 
178         cmp = t->cmp;
179         diff = cmp - current;
180         diff = (int64_t)diff > 0 ? diff : (uint64_t)1;
181         return diff;
182     }
183 }
184 
185 static void update_irq(struct HPETTimer *timer, int set)
186 {
187     uint64_t mask;
188     HPETState *s;
189     int route;
190 
191     if (timer->tn <= 1 && hpet_in_legacy_mode(timer->state)) {
192         /* if LegacyReplacementRoute bit is set, HPET specification requires
193          * timer0 be routed to IRQ0 in NON-APIC or IRQ2 in the I/O APIC,
194          * timer1 be routed to IRQ8 in NON-APIC or IRQ8 in the I/O APIC.
195          */
196         route = (timer->tn == 0) ? 0 : RTC_ISA_IRQ;
197     } else {
198         route = timer_int_route(timer);
199     }
200     s = timer->state;
201     mask = 1 << timer->tn;
202     if (!set || !timer_enabled(timer) || !hpet_enabled(timer->state)) {
203         s->isr &= ~mask;
204         if (!timer_fsb_route(timer)) {
205             qemu_irq_lower(s->irqs[route]);
206         }
207     } else if (timer_fsb_route(timer)) {
208         address_space_stl_le(&address_space_memory, timer->fsb >> 32,
209                              timer->fsb & 0xffffffff, MEMTXATTRS_UNSPECIFIED,
210                              NULL);
211     } else if (timer->config & HPET_TN_TYPE_LEVEL) {
212         s->isr |= mask;
213         qemu_irq_raise(s->irqs[route]);
214     } else {
215         s->isr &= ~mask;
216         qemu_irq_pulse(s->irqs[route]);
217     }
218 }
219 
220 static int hpet_pre_save(void *opaque)
221 {
222     HPETState *s = opaque;
223 
224     /* save current counter value */
225     if (hpet_enabled(s)) {
226         s->hpet_counter = hpet_get_ticks(s);
227     }
228 
229     return 0;
230 }
231 
232 static int hpet_pre_load(void *opaque)
233 {
234     HPETState *s = opaque;
235 
236     /* version 1 only supports 3, later versions will load the actual value */
237     s->num_timers = HPET_MIN_TIMERS;
238     return 0;
239 }
240 
241 static bool hpet_validate_num_timers(void *opaque, int version_id)
242 {
243     HPETState *s = opaque;
244 
245     if (s->num_timers < HPET_MIN_TIMERS) {
246         return false;
247     } else if (s->num_timers > HPET_MAX_TIMERS) {
248         return false;
249     }
250     return true;
251 }
252 
253 static int hpet_post_load(void *opaque, int version_id)
254 {
255     HPETState *s = opaque;
256 
257     /* Recalculate the offset between the main counter and guest time */
258     if (!s->hpet_offset_saved) {
259         s->hpet_offset = ticks_to_ns(s->hpet_counter)
260                         - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
261     }
262 
263     /* Push number of timers into capability returned via HPET_ID */
264     s->capability &= ~HPET_ID_NUM_TIM_MASK;
265     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
266     hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
267 
268     /* Derive HPET_MSI_SUPPORT from the capability of the first timer. */
269     s->flags &= ~(1 << HPET_MSI_SUPPORT);
270     if (s->timer[0].config & HPET_TN_FSB_CAP) {
271         s->flags |= 1 << HPET_MSI_SUPPORT;
272     }
273     return 0;
274 }
275 
276 static bool hpet_offset_needed(void *opaque)
277 {
278     HPETState *s = opaque;
279 
280     return hpet_enabled(s) && s->hpet_offset_saved;
281 }
282 
283 static bool hpet_rtc_irq_level_needed(void *opaque)
284 {
285     HPETState *s = opaque;
286 
287     return s->rtc_irq_level != 0;
288 }
289 
290 static const VMStateDescription vmstate_hpet_rtc_irq_level = {
291     .name = "hpet/rtc_irq_level",
292     .version_id = 1,
293     .minimum_version_id = 1,
294     .needed = hpet_rtc_irq_level_needed,
295     .fields = (VMStateField[]) {
296         VMSTATE_UINT8(rtc_irq_level, HPETState),
297         VMSTATE_END_OF_LIST()
298     }
299 };
300 
301 static const VMStateDescription vmstate_hpet_offset = {
302     .name = "hpet/offset",
303     .version_id = 1,
304     .minimum_version_id = 1,
305     .needed = hpet_offset_needed,
306     .fields = (VMStateField[]) {
307         VMSTATE_UINT64(hpet_offset, HPETState),
308         VMSTATE_END_OF_LIST()
309     }
310 };
311 
312 static const VMStateDescription vmstate_hpet_timer = {
313     .name = "hpet_timer",
314     .version_id = 1,
315     .minimum_version_id = 1,
316     .fields = (VMStateField[]) {
317         VMSTATE_UINT8(tn, HPETTimer),
318         VMSTATE_UINT64(config, HPETTimer),
319         VMSTATE_UINT64(cmp, HPETTimer),
320         VMSTATE_UINT64(fsb, HPETTimer),
321         VMSTATE_UINT64(period, HPETTimer),
322         VMSTATE_UINT8(wrap_flag, HPETTimer),
323         VMSTATE_TIMER_PTR(qemu_timer, HPETTimer),
324         VMSTATE_END_OF_LIST()
325     }
326 };
327 
328 static const VMStateDescription vmstate_hpet = {
329     .name = "hpet",
330     .version_id = 2,
331     .minimum_version_id = 1,
332     .pre_save = hpet_pre_save,
333     .pre_load = hpet_pre_load,
334     .post_load = hpet_post_load,
335     .fields = (VMStateField[]) {
336         VMSTATE_UINT64(config, HPETState),
337         VMSTATE_UINT64(isr, HPETState),
338         VMSTATE_UINT64(hpet_counter, HPETState),
339         VMSTATE_UINT8_V(num_timers, HPETState, 2),
340         VMSTATE_VALIDATE("num_timers in range", hpet_validate_num_timers),
341         VMSTATE_STRUCT_VARRAY_UINT8(timer, HPETState, num_timers, 0,
342                                     vmstate_hpet_timer, HPETTimer),
343         VMSTATE_END_OF_LIST()
344     },
345     .subsections = (const VMStateDescription*[]) {
346         &vmstate_hpet_rtc_irq_level,
347         &vmstate_hpet_offset,
348         NULL
349     }
350 };
351 
352 /*
353  * timer expiration callback
354  */
355 static void hpet_timer(void *opaque)
356 {
357     HPETTimer *t = opaque;
358     uint64_t diff;
359 
360     uint64_t period = t->period;
361     uint64_t cur_tick = hpet_get_ticks(t->state);
362 
363     if (timer_is_periodic(t) && period != 0) {
364         if (t->config & HPET_TN_32BIT) {
365             while (hpet_time_after(cur_tick, t->cmp)) {
366                 t->cmp = (uint32_t)(t->cmp + t->period);
367             }
368         } else {
369             while (hpet_time_after64(cur_tick, t->cmp)) {
370                 t->cmp += period;
371             }
372         }
373         diff = hpet_calculate_diff(t, cur_tick);
374         timer_mod(t->qemu_timer,
375                        qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + (int64_t)ticks_to_ns(diff));
376     } else if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
377         if (t->wrap_flag) {
378             diff = hpet_calculate_diff(t, cur_tick);
379             timer_mod(t->qemu_timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
380                            (int64_t)ticks_to_ns(diff));
381             t->wrap_flag = 0;
382         }
383     }
384     update_irq(t, 1);
385 }
386 
387 static void hpet_set_timer(HPETTimer *t)
388 {
389     uint64_t diff;
390     uint32_t wrap_diff;  /* how many ticks until we wrap? */
391     uint64_t cur_tick = hpet_get_ticks(t->state);
392 
393     /* whenever new timer is being set up, make sure wrap_flag is 0 */
394     t->wrap_flag = 0;
395     diff = hpet_calculate_diff(t, cur_tick);
396 
397     /* hpet spec says in one-shot 32-bit mode, generate an interrupt when
398      * counter wraps in addition to an interrupt with comparator match.
399      */
400     if (t->config & HPET_TN_32BIT && !timer_is_periodic(t)) {
401         wrap_diff = 0xffffffff - (uint32_t)cur_tick;
402         if (wrap_diff < (uint32_t)diff) {
403             diff = wrap_diff;
404             t->wrap_flag = 1;
405         }
406     }
407     timer_mod(t->qemu_timer,
408                    qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + (int64_t)ticks_to_ns(diff));
409 }
410 
411 static void hpet_del_timer(HPETTimer *t)
412 {
413     timer_del(t->qemu_timer);
414     update_irq(t, 0);
415 }
416 
417 #ifdef HPET_DEBUG
418 static uint32_t hpet_ram_readb(void *opaque, hwaddr addr)
419 {
420     printf("qemu: hpet_read b at %" PRIx64 "\n", addr);
421     return 0;
422 }
423 
424 static uint32_t hpet_ram_readw(void *opaque, hwaddr addr)
425 {
426     printf("qemu: hpet_read w at %" PRIx64 "\n", addr);
427     return 0;
428 }
429 #endif
430 
431 static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
432                               unsigned size)
433 {
434     HPETState *s = opaque;
435     uint64_t cur_tick, index;
436 
437     DPRINTF("qemu: Enter hpet_ram_readl at %" PRIx64 "\n", addr);
438     index = addr;
439     /*address range of all TN regs*/
440     if (index >= 0x100 && index <= 0x3ff) {
441         uint8_t timer_id = (addr - 0x100) / 0x20;
442         HPETTimer *timer = &s->timer[timer_id];
443 
444         if (timer_id > s->num_timers) {
445             DPRINTF("qemu: timer id out of range\n");
446             return 0;
447         }
448 
449         switch ((addr - 0x100) % 0x20) {
450         case HPET_TN_CFG:
451             return timer->config;
452         case HPET_TN_CFG + 4: // Interrupt capabilities
453             return timer->config >> 32;
454         case HPET_TN_CMP: // comparator register
455             return timer->cmp;
456         case HPET_TN_CMP + 4:
457             return timer->cmp >> 32;
458         case HPET_TN_ROUTE:
459             return timer->fsb;
460         case HPET_TN_ROUTE + 4:
461             return timer->fsb >> 32;
462         default:
463             DPRINTF("qemu: invalid hpet_ram_readl\n");
464             break;
465         }
466     } else {
467         switch (index) {
468         case HPET_ID:
469             return s->capability;
470         case HPET_PERIOD:
471             return s->capability >> 32;
472         case HPET_CFG:
473             return s->config;
474         case HPET_CFG + 4:
475             DPRINTF("qemu: invalid HPET_CFG + 4 hpet_ram_readl\n");
476             return 0;
477         case HPET_COUNTER:
478             if (hpet_enabled(s)) {
479                 cur_tick = hpet_get_ticks(s);
480             } else {
481                 cur_tick = s->hpet_counter;
482             }
483             DPRINTF("qemu: reading counter  = %" PRIx64 "\n", cur_tick);
484             return cur_tick;
485         case HPET_COUNTER + 4:
486             if (hpet_enabled(s)) {
487                 cur_tick = hpet_get_ticks(s);
488             } else {
489                 cur_tick = s->hpet_counter;
490             }
491             DPRINTF("qemu: reading counter + 4  = %" PRIx64 "\n", cur_tick);
492             return cur_tick >> 32;
493         case HPET_STATUS:
494             return s->isr;
495         default:
496             DPRINTF("qemu: invalid hpet_ram_readl\n");
497             break;
498         }
499     }
500     return 0;
501 }
502 
503 static void hpet_ram_write(void *opaque, hwaddr addr,
504                            uint64_t value, unsigned size)
505 {
506     int i;
507     HPETState *s = opaque;
508     uint64_t old_val, new_val, val, index;
509 
510     DPRINTF("qemu: Enter hpet_ram_writel at %" PRIx64 " = %#x\n", addr, value);
511     index = addr;
512     old_val = hpet_ram_read(opaque, addr, 4);
513     new_val = value;
514 
515     /*address range of all TN regs*/
516     if (index >= 0x100 && index <= 0x3ff) {
517         uint8_t timer_id = (addr - 0x100) / 0x20;
518         HPETTimer *timer = &s->timer[timer_id];
519 
520         DPRINTF("qemu: hpet_ram_writel timer_id = %#x\n", timer_id);
521         if (timer_id > s->num_timers) {
522             DPRINTF("qemu: timer id out of range\n");
523             return;
524         }
525         switch ((addr - 0x100) % 0x20) {
526         case HPET_TN_CFG:
527             DPRINTF("qemu: hpet_ram_writel HPET_TN_CFG\n");
528             if (activating_bit(old_val, new_val, HPET_TN_FSB_ENABLE)) {
529                 update_irq(timer, 0);
530             }
531             val = hpet_fixup_reg(new_val, old_val, HPET_TN_CFG_WRITE_MASK);
532             timer->config = (timer->config & 0xffffffff00000000ULL) | val;
533             if (new_val & HPET_TN_32BIT) {
534                 timer->cmp = (uint32_t)timer->cmp;
535                 timer->period = (uint32_t)timer->period;
536             }
537             if (activating_bit(old_val, new_val, HPET_TN_ENABLE) &&
538                 hpet_enabled(s)) {
539                 hpet_set_timer(timer);
540             } else if (deactivating_bit(old_val, new_val, HPET_TN_ENABLE)) {
541                 hpet_del_timer(timer);
542             }
543             break;
544         case HPET_TN_CFG + 4: // Interrupt capabilities
545             DPRINTF("qemu: invalid HPET_TN_CFG+4 write\n");
546             break;
547         case HPET_TN_CMP: // comparator register
548             DPRINTF("qemu: hpet_ram_writel HPET_TN_CMP\n");
549             if (timer->config & HPET_TN_32BIT) {
550                 new_val = (uint32_t)new_val;
551             }
552             if (!timer_is_periodic(timer)
553                 || (timer->config & HPET_TN_SETVAL)) {
554                 timer->cmp = (timer->cmp & 0xffffffff00000000ULL) | new_val;
555             }
556             if (timer_is_periodic(timer)) {
557                 /*
558                  * FIXME: Clamp period to reasonable min value?
559                  * Clamp period to reasonable max value
560                  */
561                 new_val &= (timer->config & HPET_TN_32BIT ? ~0u : ~0ull) >> 1;
562                 timer->period =
563                     (timer->period & 0xffffffff00000000ULL) | new_val;
564             }
565             timer->config &= ~HPET_TN_SETVAL;
566             if (hpet_enabled(s)) {
567                 hpet_set_timer(timer);
568             }
569             break;
570         case HPET_TN_CMP + 4: // comparator register high order
571             DPRINTF("qemu: hpet_ram_writel HPET_TN_CMP + 4\n");
572             if (!timer_is_periodic(timer)
573                 || (timer->config & HPET_TN_SETVAL)) {
574                 timer->cmp = (timer->cmp & 0xffffffffULL) | new_val << 32;
575             } else {
576                 /*
577                  * FIXME: Clamp period to reasonable min value?
578                  * Clamp period to reasonable max value
579                  */
580                 new_val &= (timer->config & HPET_TN_32BIT ? ~0u : ~0ull) >> 1;
581                 timer->period =
582                     (timer->period & 0xffffffffULL) | new_val << 32;
583                 }
584                 timer->config &= ~HPET_TN_SETVAL;
585                 if (hpet_enabled(s)) {
586                     hpet_set_timer(timer);
587                 }
588                 break;
589         case HPET_TN_ROUTE:
590             timer->fsb = (timer->fsb & 0xffffffff00000000ULL) | new_val;
591             break;
592         case HPET_TN_ROUTE + 4:
593             timer->fsb = (new_val << 32) | (timer->fsb & 0xffffffff);
594             break;
595         default:
596             DPRINTF("qemu: invalid hpet_ram_writel\n");
597             break;
598         }
599         return;
600     } else {
601         switch (index) {
602         case HPET_ID:
603             return;
604         case HPET_CFG:
605             val = hpet_fixup_reg(new_val, old_val, HPET_CFG_WRITE_MASK);
606             s->config = (s->config & 0xffffffff00000000ULL) | val;
607             if (activating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
608                 /* Enable main counter and interrupt generation. */
609                 s->hpet_offset =
610                     ticks_to_ns(s->hpet_counter) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
611                 for (i = 0; i < s->num_timers; i++) {
612                     if ((&s->timer[i])->cmp != ~0ULL) {
613                         hpet_set_timer(&s->timer[i]);
614                     }
615                 }
616             } else if (deactivating_bit(old_val, new_val, HPET_CFG_ENABLE)) {
617                 /* Halt main counter and disable interrupt generation. */
618                 s->hpet_counter = hpet_get_ticks(s);
619                 for (i = 0; i < s->num_timers; i++) {
620                     hpet_del_timer(&s->timer[i]);
621                 }
622             }
623             /* i8254 and RTC output pins are disabled
624              * when HPET is in legacy mode */
625             if (activating_bit(old_val, new_val, HPET_CFG_LEGACY)) {
626                 qemu_set_irq(s->pit_enabled, 0);
627                 qemu_irq_lower(s->irqs[0]);
628                 qemu_irq_lower(s->irqs[RTC_ISA_IRQ]);
629             } else if (deactivating_bit(old_val, new_val, HPET_CFG_LEGACY)) {
630                 qemu_irq_lower(s->irqs[0]);
631                 qemu_set_irq(s->pit_enabled, 1);
632                 qemu_set_irq(s->irqs[RTC_ISA_IRQ], s->rtc_irq_level);
633             }
634             break;
635         case HPET_CFG + 4:
636             DPRINTF("qemu: invalid HPET_CFG+4 write\n");
637             break;
638         case HPET_STATUS:
639             val = new_val & s->isr;
640             for (i = 0; i < s->num_timers; i++) {
641                 if (val & (1 << i)) {
642                     update_irq(&s->timer[i], 0);
643                 }
644             }
645             break;
646         case HPET_COUNTER:
647             if (hpet_enabled(s)) {
648                 DPRINTF("qemu: Writing counter while HPET enabled!\n");
649             }
650             s->hpet_counter =
651                 (s->hpet_counter & 0xffffffff00000000ULL) | value;
652             DPRINTF("qemu: HPET counter written. ctr = %#x -> %" PRIx64 "\n",
653                     value, s->hpet_counter);
654             break;
655         case HPET_COUNTER + 4:
656             if (hpet_enabled(s)) {
657                 DPRINTF("qemu: Writing counter while HPET enabled!\n");
658             }
659             s->hpet_counter =
660                 (s->hpet_counter & 0xffffffffULL) | (((uint64_t)value) << 32);
661             DPRINTF("qemu: HPET counter + 4 written. ctr = %#x -> %" PRIx64 "\n",
662                     value, s->hpet_counter);
663             break;
664         default:
665             DPRINTF("qemu: invalid hpet_ram_writel\n");
666             break;
667         }
668     }
669 }
670 
671 static const MemoryRegionOps hpet_ram_ops = {
672     .read = hpet_ram_read,
673     .write = hpet_ram_write,
674     .valid = {
675         .min_access_size = 4,
676         .max_access_size = 4,
677     },
678     .endianness = DEVICE_NATIVE_ENDIAN,
679 };
680 
681 static void hpet_reset(DeviceState *d)
682 {
683     HPETState *s = HPET(d);
684     SysBusDevice *sbd = SYS_BUS_DEVICE(d);
685     int i;
686 
687     for (i = 0; i < s->num_timers; i++) {
688         HPETTimer *timer = &s->timer[i];
689 
690         hpet_del_timer(timer);
691         timer->cmp = ~0ULL;
692         timer->config = HPET_TN_PERIODIC_CAP | HPET_TN_SIZE_CAP;
693         if (s->flags & (1 << HPET_MSI_SUPPORT)) {
694             timer->config |= HPET_TN_FSB_CAP;
695         }
696         /* advertise availability of ioapic int */
697         timer->config |=  (uint64_t)s->intcap << 32;
698         timer->period = 0ULL;
699         timer->wrap_flag = 0;
700     }
701 
702     qemu_set_irq(s->pit_enabled, 1);
703     s->hpet_counter = 0ULL;
704     s->hpet_offset = 0ULL;
705     s->config = 0ULL;
706     hpet_cfg.hpet[s->hpet_id].event_timer_block_id = (uint32_t)s->capability;
707     hpet_cfg.hpet[s->hpet_id].address = sbd->mmio[0].addr;
708 
709     /* to document that the RTC lowers its output on reset as well */
710     s->rtc_irq_level = 0;
711 }
712 
713 static void hpet_handle_legacy_irq(void *opaque, int n, int level)
714 {
715     HPETState *s = HPET(opaque);
716 
717     if (n == HPET_LEGACY_PIT_INT) {
718         if (!hpet_in_legacy_mode(s)) {
719             qemu_set_irq(s->irqs[0], level);
720         }
721     } else {
722         s->rtc_irq_level = level;
723         if (!hpet_in_legacy_mode(s)) {
724             qemu_set_irq(s->irqs[RTC_ISA_IRQ], level);
725         }
726     }
727 }
728 
729 static void hpet_init(Object *obj)
730 {
731     SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
732     HPETState *s = HPET(obj);
733 
734     /* HPET Area */
735     memory_region_init_io(&s->iomem, obj, &hpet_ram_ops, s, "hpet", HPET_LEN);
736     sysbus_init_mmio(sbd, &s->iomem);
737 }
738 
739 static void hpet_realize(DeviceState *dev, Error **errp)
740 {
741     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
742     HPETState *s = HPET(dev);
743     int i;
744     HPETTimer *timer;
745 
746     if (!s->intcap) {
747         error_printf("Hpet's intcap not initialized.\n");
748     }
749     if (hpet_cfg.count == UINT8_MAX) {
750         /* first instance */
751         hpet_cfg.count = 0;
752     }
753 
754     if (hpet_cfg.count == 8) {
755         error_setg(errp, "Only 8 instances of HPET is allowed");
756         return;
757     }
758 
759     s->hpet_id = hpet_cfg.count++;
760 
761     for (i = 0; i < HPET_NUM_IRQ_ROUTES; i++) {
762         sysbus_init_irq(sbd, &s->irqs[i]);
763     }
764 
765     if (s->num_timers < HPET_MIN_TIMERS) {
766         s->num_timers = HPET_MIN_TIMERS;
767     } else if (s->num_timers > HPET_MAX_TIMERS) {
768         s->num_timers = HPET_MAX_TIMERS;
769     }
770     for (i = 0; i < HPET_MAX_TIMERS; i++) {
771         timer = &s->timer[i];
772         timer->qemu_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, hpet_timer, timer);
773         timer->tn = i;
774         timer->state = s;
775     }
776 
777     /* 64-bit main counter; LegacyReplacementRoute. */
778     s->capability = 0x8086a001ULL;
779     s->capability |= (s->num_timers - 1) << HPET_ID_NUM_TIM_SHIFT;
780     s->capability |= ((uint64_t)(HPET_CLK_PERIOD * FS_PER_NS) << 32);
781 
782     qdev_init_gpio_in(dev, hpet_handle_legacy_irq, 2);
783     qdev_init_gpio_out(dev, &s->pit_enabled, 1);
784 }
785 
786 static Property hpet_device_properties[] = {
787     DEFINE_PROP_UINT8("timers", HPETState, num_timers, HPET_MIN_TIMERS),
788     DEFINE_PROP_BIT("msi", HPETState, flags, HPET_MSI_SUPPORT, false),
789     DEFINE_PROP_UINT32(HPET_INTCAP, HPETState, intcap, 0),
790     DEFINE_PROP_BOOL("hpet-offset-saved", HPETState, hpet_offset_saved, true),
791     DEFINE_PROP_END_OF_LIST(),
792 };
793 
794 static void hpet_device_class_init(ObjectClass *klass, void *data)
795 {
796     DeviceClass *dc = DEVICE_CLASS(klass);
797 
798     dc->realize = hpet_realize;
799     dc->reset = hpet_reset;
800     dc->vmsd = &vmstate_hpet;
801     dc->props = hpet_device_properties;
802 }
803 
804 static const TypeInfo hpet_device_info = {
805     .name          = TYPE_HPET,
806     .parent        = TYPE_SYS_BUS_DEVICE,
807     .instance_size = sizeof(HPETState),
808     .instance_init = hpet_init,
809     .class_init    = hpet_device_class_init,
810 };
811 
812 static void hpet_register_types(void)
813 {
814     type_register_static(&hpet_device_info);
815 }
816 
817 type_init(hpet_register_types)
818