hw/rtc/goldfish_rtc.c

   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 = {
 220     .read = goldfish_rtc_read,
 221     .write = goldfish_rtc_write,
 222     .endianness = DEVICE_NATIVE_ENDIAN,
 223     .valid = {
 224         .min_access_size = 4,
 225         .max_access_size = 4
 226     }
 227 };
 228
 229 static const VMStateDescription goldfish_rtc_vmstate = {
 230     .name = TYPE_GOLDFISH_RTC,
 231     .version_id = 2,
 232     .pre_save = goldfish_rtc_pre_save,
 233     .post_load = goldfish_rtc_post_load,
 234     .fields = (VMStateField[]) {
 235         VMSTATE_UINT64(tick_offset_vmstate, GoldfishRTCState),
 236         VMSTATE_UINT64(alarm_next, GoldfishRTCState),
 237         VMSTATE_UINT32(alarm_running, GoldfishRTCState),
 238         VMSTATE_UINT32(irq_pending, GoldfishRTCState),
 239         VMSTATE_UINT32(irq_enabled, GoldfishRTCState),
 240         VMSTATE_UINT32(time_high, GoldfishRTCState),
 241         VMSTATE_END_OF_LIST()
 242     }
 243 };
 244
 245 static void goldfish_rtc_reset(DeviceState *dev)
 246 {
 247     GoldfishRTCState *s = GOLDFISH_RTC(dev);
 248     struct tm tm;
 249
 250     timer_del(s->timer);
 251
 252     qemu_get_timedate(&tm, 0);
 253     s->tick_offset = mktimegm(&tm);
 254     s->tick_offset *= NANOSECONDS_PER_SECOND;
 255     s->tick_offset -= qemu_clock_get_ns(rtc_clock);
 256     s->tick_offset_vmstate = 0;
 257     s->alarm_next = 0;
 258     s->alarm_running = 0;
 259     s->irq_pending = 0;
 260     s->irq_enabled = 0;
 261 }
 262
 263 static void goldfish_rtc_realize(DeviceState *d, Error **errp)
 264 {
 265     SysBusDevice *dev = SYS_BUS_DEVICE(d);
 266     GoldfishRTCState *s = GOLDFISH_RTC(d);
 267
 268     memory_region_init_io(&s->iomem, OBJECT(s), &goldfish_rtc_ops, s,
 269                           "goldfish_rtc", 0x24);
 270     sysbus_init_mmio(dev, &s->iomem);
 271
 272     sysbus_init_irq(dev, &s->irq);
 273
 274     s->timer = timer_new_ns(rtc_clock, goldfish_rtc_interrupt, s);
 275 }
 276
 277 static void goldfish_rtc_class_init(ObjectClass *klass, void *data)
 278 {
 279     DeviceClass *dc = DEVICE_CLASS(klass);
 280
 281     dc->realize = goldfish_rtc_realize;
 282     dc->reset = goldfish_rtc_reset;
 283     dc->vmsd = &goldfish_rtc_vmstate;
 284 }
 285
 286 static const TypeInfo goldfish_rtc_info = {
 287     .name          = TYPE_GOLDFISH_RTC,
 288     .parent        = TYPE_SYS_BUS_DEVICE,
 289     .instance_size = sizeof(GoldfishRTCState),
 290     .class_init    = goldfish_rtc_class_init,
 291 };
 292
 293 static void goldfish_rtc_register_types(void)
 294 {
 295     type_register_static(&goldfish_rtc_info);
 296 }
 297
 298 type_init(goldfish_rtc_register_types)