xref: /openbmc/qemu/hw/rtc/goldfish_rtc.c (revision 2b74dd91)
1 /*
2  * Goldfish virtual platform RTC
3  *
4  * Copyright (C) 2019 Western Digital Corporation or its affiliates.
5  *
6  * For more details on Google Goldfish virtual platform refer:
7  * https://android.googlesource.com/platform/external/qemu/+/refs/heads/emu-2.0-release/docs/GOLDFISH-VIRTUAL-HARDWARE.TXT
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms and conditions of the GNU General Public License,
11  * version 2 or later, as published by the Free Software Foundation.
12  *
13  * This program is distributed in the hope it will be useful, but WITHOUT
14  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
15  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
16  * more details.
17  *
18  * You should have received a copy of the GNU General Public License along with
19  * this program.  If not, see <http://www.gnu.org/licenses/>.
20  */
21 
22 #include "qemu/osdep.h"
23 #include "hw/rtc/goldfish_rtc.h"
24 #include "migration/vmstate.h"
25 #include "hw/irq.h"
26 #include "hw/qdev-properties.h"
27 #include "hw/sysbus.h"
28 #include "qemu/bitops.h"
29 #include "qemu/timer.h"
30 #include "sysemu/sysemu.h"
31 #include "sysemu/rtc.h"
32 #include "qemu/cutils.h"
33 #include "qemu/log.h"
34 
35 #include "trace.h"
36 
37 #define RTC_TIME_LOW            0x00
38 #define RTC_TIME_HIGH           0x04
39 #define RTC_ALARM_LOW           0x08
40 #define RTC_ALARM_HIGH          0x0c
41 #define RTC_IRQ_ENABLED         0x10
42 #define RTC_CLEAR_ALARM         0x14
43 #define RTC_ALARM_STATUS        0x18
44 #define RTC_CLEAR_INTERRUPT     0x1c
45 
46 static void goldfish_rtc_update(GoldfishRTCState *s)
47 {
48     qemu_set_irq(s->irq, (s->irq_pending & s->irq_enabled) ? 1 : 0);
49 }
50 
51 static void goldfish_rtc_interrupt(void *opaque)
52 {
53     GoldfishRTCState *s = (GoldfishRTCState *)opaque;
54 
55     s->alarm_running = 0;
56     s->irq_pending = 1;
57     goldfish_rtc_update(s);
58 }
59 
60 static uint64_t goldfish_rtc_get_count(GoldfishRTCState *s)
61 {
62     return s->tick_offset + (uint64_t)qemu_clock_get_ns(rtc_clock);
63 }
64 
65 static void goldfish_rtc_clear_alarm(GoldfishRTCState *s)
66 {
67     timer_del(s->timer);
68     s->alarm_running = 0;
69 }
70 
71 static void goldfish_rtc_set_alarm(GoldfishRTCState *s)
72 {
73     uint64_t ticks = goldfish_rtc_get_count(s);
74     uint64_t event = s->alarm_next;
75 
76     if (event <= ticks) {
77         goldfish_rtc_clear_alarm(s);
78         goldfish_rtc_interrupt(s);
79     } else {
80         /*
81          * We should be setting timer expiry to:
82          *     qemu_clock_get_ns(rtc_clock) + (event - ticks)
83          * but this is equivalent to:
84          *     event - s->tick_offset
85          */
86         timer_mod(s->timer, event - s->tick_offset);
87         s->alarm_running = 1;
88     }
89 }
90 
91 static uint64_t goldfish_rtc_read(void *opaque, hwaddr offset,
92                                   unsigned size)
93 {
94     GoldfishRTCState *s = opaque;
95     uint64_t r = 0;
96 
97     /*
98      * From the documentation linked at the top of the file:
99      *
100      *   To read the value, the kernel must perform an IO_READ(TIME_LOW), which
101      *   returns an unsigned 32-bit value, before an IO_READ(TIME_HIGH), which
102      *   returns a signed 32-bit value, corresponding to the higher half of the
103      *   full value.
104      */
105     switch (offset) {
106     case RTC_TIME_LOW:
107         r = goldfish_rtc_get_count(s);
108         s->time_high = r >> 32;
109         r &= 0xffffffff;
110         break;
111     case RTC_TIME_HIGH:
112         r = s->time_high;
113         break;
114     case RTC_ALARM_LOW:
115         r = s->alarm_next & 0xffffffff;
116         break;
117     case RTC_ALARM_HIGH:
118         r = s->alarm_next >> 32;
119         break;
120     case RTC_IRQ_ENABLED:
121         r = s->irq_enabled;
122         break;
123     case RTC_ALARM_STATUS:
124         r = s->alarm_running;
125         break;
126     default:
127         qemu_log_mask(LOG_GUEST_ERROR,
128                   "%s: offset 0x%x is UNIMP.\n", __func__, (uint32_t)offset);
129         break;
130     }
131 
132     trace_goldfish_rtc_read(offset, r);
133 
134     return r;
135 }
136 
137 static void goldfish_rtc_write(void *opaque, hwaddr offset,
138                                uint64_t value, unsigned size)
139 {
140     GoldfishRTCState *s = opaque;
141     uint64_t current_tick, new_tick;
142 
143     switch (offset) {
144     case RTC_TIME_LOW:
145         current_tick = goldfish_rtc_get_count(s);
146         new_tick = deposit64(current_tick, 0, 32, value);
147         s->tick_offset += new_tick - current_tick;
148         break;
149     case RTC_TIME_HIGH:
150         current_tick = goldfish_rtc_get_count(s);
151         new_tick = deposit64(current_tick, 32, 32, value);
152         s->tick_offset += new_tick - current_tick;
153         break;
154     case RTC_ALARM_LOW:
155         s->alarm_next = deposit64(s->alarm_next, 0, 32, value);
156         goldfish_rtc_set_alarm(s);
157         break;
158     case RTC_ALARM_HIGH:
159         s->alarm_next = deposit64(s->alarm_next, 32, 32, value);
160         break;
161     case RTC_IRQ_ENABLED:
162         s->irq_enabled = (uint32_t)(value & 0x1);
163         goldfish_rtc_update(s);
164         break;
165     case RTC_CLEAR_ALARM:
166         goldfish_rtc_clear_alarm(s);
167         break;
168     case RTC_CLEAR_INTERRUPT:
169         s->irq_pending = 0;
170         goldfish_rtc_update(s);
171         break;
172     default:
173         qemu_log_mask(LOG_GUEST_ERROR,
174                   "%s: offset 0x%x is UNIMP.\n", __func__, (uint32_t)offset);
175         break;
176     }
177 
178     trace_goldfish_rtc_write(offset, value);
179 }
180 
181 static int goldfish_rtc_pre_save(void *opaque)
182 {
183     uint64_t delta;
184     GoldfishRTCState *s = opaque;
185 
186     /*
187      * We want to migrate this offset, which sounds straightforward.
188      * Unfortunately, we cannot directly pass tick_offset because
189      * rtc_clock on destination Host might not be same source Host.
190      *
191      * To tackle, this we pass tick_offset relative to vm_clock from
192      * source Host and make it relative to rtc_clock at destination Host.
193      */
194     delta = qemu_clock_get_ns(rtc_clock) -
195             qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
196     s->tick_offset_vmstate = s->tick_offset + delta;
197 
198     return 0;
199 }
200 
201 static int goldfish_rtc_post_load(void *opaque, int version_id)
202 {
203     uint64_t delta;
204     GoldfishRTCState *s = opaque;
205 
206     /*
207      * We extract tick_offset from tick_offset_vmstate by doing
208      * reverse math compared to pre_save() function.
209      */
210     delta = qemu_clock_get_ns(rtc_clock) -
211             qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
212     s->tick_offset = s->tick_offset_vmstate - delta;
213 
214     goldfish_rtc_set_alarm(s);
215 
216     return 0;
217 }
218 
219 static const MemoryRegionOps goldfish_rtc_ops[2] = {
220     [false] = {
221         .read = goldfish_rtc_read,
222         .write = goldfish_rtc_write,
223         .endianness = DEVICE_LITTLE_ENDIAN,
224         .valid = {
225             .min_access_size = 4,
226             .max_access_size = 4
227         }
228     },
229     [true] = {
230         .read = goldfish_rtc_read,
231         .write = goldfish_rtc_write,
232         .endianness = DEVICE_BIG_ENDIAN,
233         .valid = {
234             .min_access_size = 4,
235             .max_access_size = 4
236         }
237     },
238 };
239 
240 static const VMStateDescription goldfish_rtc_vmstate = {
241     .name = TYPE_GOLDFISH_RTC,
242     .version_id = 2,
243     .pre_save = goldfish_rtc_pre_save,
244     .post_load = goldfish_rtc_post_load,
245     .fields = (const VMStateField[]) {
246         VMSTATE_UINT64(tick_offset_vmstate, GoldfishRTCState),
247         VMSTATE_UINT64(alarm_next, GoldfishRTCState),
248         VMSTATE_UINT32(alarm_running, GoldfishRTCState),
249         VMSTATE_UINT32(irq_pending, GoldfishRTCState),
250         VMSTATE_UINT32(irq_enabled, GoldfishRTCState),
251         VMSTATE_UINT32(time_high, GoldfishRTCState),
252         VMSTATE_END_OF_LIST()
253     }
254 };
255 
256 static void goldfish_rtc_reset(DeviceState *dev)
257 {
258     GoldfishRTCState *s = GOLDFISH_RTC(dev);
259     struct tm tm;
260 
261     timer_del(s->timer);
262 
263     qemu_get_timedate(&tm, 0);
264     s->tick_offset = mktimegm(&tm);
265     s->tick_offset *= NANOSECONDS_PER_SECOND;
266     s->tick_offset -= qemu_clock_get_ns(rtc_clock);
267     s->tick_offset_vmstate = 0;
268     s->alarm_next = 0;
269     s->alarm_running = 0;
270     s->irq_pending = 0;
271     s->irq_enabled = 0;
272 }
273 
274 static void goldfish_rtc_realize(DeviceState *d, Error **errp)
275 {
276     SysBusDevice *dev = SYS_BUS_DEVICE(d);
277     GoldfishRTCState *s = GOLDFISH_RTC(d);
278 
279     memory_region_init_io(&s->iomem, OBJECT(s),
280                           &goldfish_rtc_ops[s->big_endian], s,
281                           "goldfish_rtc", 0x24);
282     sysbus_init_mmio(dev, &s->iomem);
283 
284     sysbus_init_irq(dev, &s->irq);
285 
286     s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
287 }
288 
289 static Property goldfish_rtc_properties[] = {
290     DEFINE_PROP_BOOL("big-endian", GoldfishRTCState, big_endian,
291                       false),
292     DEFINE_PROP_END_OF_LIST(),
293 };
294 
295 static void goldfish_rtc_class_init(ObjectClass *klass, void *data)
296 {
297     DeviceClass *dc = DEVICE_CLASS(klass);
298 
299     device_class_set_props(dc, goldfish_rtc_properties);
300     dc->realize = goldfish_rtc_realize;
301     device_class_set_legacy_reset(dc, goldfish_rtc_reset);
302     dc->vmsd = &goldfish_rtc_vmstate;
303 }
304 
305 static const TypeInfo goldfish_rtc_info = {
306     .name          = TYPE_GOLDFISH_RTC,
307     .parent        = TYPE_SYS_BUS_DEVICE,
308     .instance_size = sizeof(GoldfishRTCState),
309     .class_init    = goldfish_rtc_class_init,
310 };
311 
312 static void goldfish_rtc_register_types(void)
313 {
314     type_register_static(&goldfish_rtc_info);
315 }
316 
317 type_init(goldfish_rtc_register_types)
318