hw/timer/pl031.c

   1 /*
   2  * ARM AMBA PrimeCell PL031 RTC
   3  *
   4  * Copyright (c) 2007 CodeSourcery
   5  *
   6  * This file is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Contributions after 2012-01-13 are licensed under the terms of the
  11  * GNU GPL, version 2 or (at your option) any later version.
  12  */
  13
  14 #include "hw/sysbus.h"
  15 #include "qemu/timer.h"
  16 #include "sysemu/sysemu.h"
  17
  18 //#define DEBUG_PL031
  19
  20 #ifdef DEBUG_PL031
  21 #define DPRINTF(fmt, ...) \
  22 do { printf("pl031: " fmt , ## __VA_ARGS__); } while (0)
  23 #else
  24 #define DPRINTF(fmt, ...) do {} while(0)
  25 #endif
  26
  27 #define RTC_DR      0x00    /* Data read register */
  28 #define RTC_MR      0x04    /* Match register */
  29 #define RTC_LR      0x08    /* Data load register */
  30 #define RTC_CR      0x0c    /* Control register */
  31 #define RTC_IMSC    0x10    /* Interrupt mask and set register */
  32 #define RTC_RIS     0x14    /* Raw interrupt status register */
  33 #define RTC_MIS     0x18    /* Masked interrupt status register */
  34 #define RTC_ICR     0x1c    /* Interrupt clear register */
  35
  36 #define TYPE_PL031 "pl031"
  37 #define PL031(obj) OBJECT_CHECK(PL031State, (obj), TYPE_PL031)
  38
  39 typedef struct PL031State {
  40     SysBusDevice parent_obj;
  41
  42     MemoryRegion iomem;
  43     QEMUTimer *timer;
  44     qemu_irq irq;
  45
  46     /* Needed to preserve the tick_count across migration, even if the
  47      * absolute value of the rtc_clock is different on the source and
  48      * destination.
  49      */
  50     uint32_t tick_offset_vmstate;
  51     uint32_t tick_offset;
  52
  53     uint32_t mr;
  54     uint32_t lr;
  55     uint32_t cr;
  56     uint32_t im;
  57     uint32_t is;
  58 } PL031State;
  59
  60 static const unsigned char pl031_id[] = {
  61     0x31, 0x10, 0x14, 0x00,         /* Device ID        */
  62     0x0d, 0xf0, 0x05, 0xb1          /* Cell ID      */
  63 };
  64
  65 static void pl031_update(PL031State *s)
  66 {
  67     qemu_set_irq(s->irq, s->is & s->im);
  68 }
  69
  70 static void pl031_interrupt(void * opaque)
  71 {
  72     PL031State *s = (PL031State *)opaque;
  73
  74     s->is = 1;
  75     DPRINTF("Alarm raised\n");
  76     pl031_update(s);
  77 }
  78
  79 static uint32_t pl031_get_count(PL031State *s)
  80 {
  81     int64_t now = qemu_clock_get_ns(rtc_clock);
  82     return s->tick_offset + now / get_ticks_per_sec();
  83 }
  84
  85 static void pl031_set_alarm(PL031State *s)
  86 {
  87     uint32_t ticks;
  88
  89     /* The timer wraps around.  This subtraction also wraps in the same way,
  90        and gives correct results when alarm < now_ticks.  */
  91     ticks = s->mr - pl031_get_count(s);
  92     DPRINTF("Alarm set in %ud ticks\n", ticks);
  93     if (ticks == 0) {
  94         timer_del(s->timer);
  95         pl031_interrupt(s);
  96     } else {
  97         int64_t now = qemu_clock_get_ns(rtc_clock);
  98         timer_mod(s->timer, now + (int64_t)ticks * get_ticks_per_sec());
  99     }
 100 }
 101
 102 static uint64_t pl031_read(void *opaque, hwaddr offset,
 103                            unsigned size)
 104 {
 105     PL031State *s = (PL031State *)opaque;
 106
 107     if (offset >= 0xfe0  &&  offset < 0x1000)
 108         return pl031_id[(offset - 0xfe0) >> 2];
 109
 110     switch (offset) {
 111     case RTC_DR:
 112         return pl031_get_count(s);
 113     case RTC_MR:
 114         return s->mr;
 115     case RTC_IMSC:
 116         return s->im;
 117     case RTC_RIS:
 118         return s->is;
 119     case RTC_LR:
 120         return s->lr;
 121     case RTC_CR:
 122         /* RTC is permanently enabled.  */
 123         return 1;
 124     case RTC_MIS:
 125         return s->is & s->im;
 126     case RTC_ICR:
 127         qemu_log_mask(LOG_GUEST_ERROR,
 128                       "pl031: read of write-only register at offset 0x%x\n",
 129                       (int)offset);
 130         break;
 131     default:
 132         qemu_log_mask(LOG_GUEST_ERROR,
 133                       "pl031_read: Bad offset 0x%x\n", (int)offset);
 134         break;
 135     }
 136
 137     return 0;
 138 }
 139
 140 static void pl031_write(void * opaque, hwaddr offset,
 141                         uint64_t value, unsigned size)
 142 {
 143     PL031State *s = (PL031State *)opaque;
 144
 145
 146     switch (offset) {
 147     case RTC_LR:
 148         s->tick_offset += value - pl031_get_count(s);
 149         pl031_set_alarm(s);
 150         break;
 151     case RTC_MR:
 152         s->mr = value;
 153         pl031_set_alarm(s);
 154         break;
 155     case RTC_IMSC:
 156         s->im = value & 1;
 157         DPRINTF("Interrupt mask %d\n", s->im);
 158         pl031_update(s);
 159         break;
 160     case RTC_ICR:
 161         /* The PL031 documentation (DDI0224B) states that the interrupt is
 162            cleared when bit 0 of the written value is set.  However the
 163            arm926e documentation (DDI0287B) states that the interrupt is
 164            cleared when any value is written.  */
 165         DPRINTF("Interrupt cleared");
 166         s->is = 0;
 167         pl031_update(s);
 168         break;
 169     case RTC_CR:
 170         /* Written value is ignored.  */
 171         break;
 172
 173     case RTC_DR:
 174     case RTC_MIS:
 175     case RTC_RIS:
 176         qemu_log_mask(LOG_GUEST_ERROR,
 177                       "pl031: write to read-only register at offset 0x%x\n",
 178                       (int)offset);
 179         break;
 180
 181     default:
 182         qemu_log_mask(LOG_GUEST_ERROR,
 183                       "pl031_write: Bad offset 0x%x\n", (int)offset);
 184         break;
 185     }
 186 }
 187
 188 static const MemoryRegionOps pl031_ops = {
 189     .read = pl031_read,
 190     .write = pl031_write,
 191     .endianness = DEVICE_NATIVE_ENDIAN,
 192 };
 193
 194 static int pl031_init(SysBusDevice *dev)
 195 {
 196     PL031State *s = PL031(dev);
 197     struct tm tm;
 198
 199     memory_region_init_io(&s->iomem, OBJECT(s), &pl031_ops, s, "pl031", 0x1000);
 200     sysbus_init_mmio(dev, &s->iomem);
 201
 202     sysbus_init_irq(dev, &s->irq);
 203     qemu_get_timedate(&tm, 0);
 204     s->tick_offset = mktimegm(&tm) -
 205         qemu_clock_get_ns(rtc_clock) / get_ticks_per_sec();
 206
 207     s->timer = timer_new_ns(rtc_clock, pl031_interrupt, s);
 208     return 0;
 209 }
 210
 211 static void pl031_pre_save(void *opaque)
 212 {
 213     PL031State *s = opaque;
 214
 215     /* tick_offset is base_time - rtc_clock base time.  Instead, we want to
 216      * store the base time relative to the QEMU_CLOCK_VIRTUAL for backwards-compatibility.  */
 217     int64_t delta = qemu_clock_get_ns(rtc_clock) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 218     s->tick_offset_vmstate = s->tick_offset + delta / get_ticks_per_sec();
 219 }
 220
 221 static int pl031_post_load(void *opaque, int version_id)
 222 {
 223     PL031State *s = opaque;
 224
 225     int64_t delta = qemu_clock_get_ns(rtc_clock) - qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
 226     s->tick_offset = s->tick_offset_vmstate - delta / get_ticks_per_sec();
 227     pl031_set_alarm(s);
 228     return 0;
 229 }
 230
 231 static const VMStateDescription vmstate_pl031 = {
 232     .name = "pl031",
 233     .version_id = 1,
 234     .minimum_version_id = 1,
 235     .pre_save = pl031_pre_save,
 236     .post_load = pl031_post_load,
 237     .fields = (VMStateField[]) {
 238         VMSTATE_UINT32(tick_offset_vmstate, PL031State),
 239         VMSTATE_UINT32(mr, PL031State),
 240         VMSTATE_UINT32(lr, PL031State),
 241         VMSTATE_UINT32(cr, PL031State),
 242         VMSTATE_UINT32(im, PL031State),
 243         VMSTATE_UINT32(is, PL031State),
 244         VMSTATE_END_OF_LIST()
 245     }
 246 };
 247
 248 static void pl031_class_init(ObjectClass *klass, void *data)
 249 {
 250     DeviceClass *dc = DEVICE_CLASS(klass);
 251     SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
 252
 253     k->init = pl031_init;
 254     dc->no_user = 1;
 255     dc->vmsd = &vmstate_pl031;
 256 }
 257
 258 static const TypeInfo pl031_info = {
 259     .name          = TYPE_PL031,
 260     .parent        = TYPE_SYS_BUS_DEVICE,
 261     .instance_size = sizeof(PL031State),
 262     .class_init    = pl031_class_init,
 263 };
 264
 265 static void pl031_register_types(void)
 266 {
 267     type_register_static(&pl031_info);
 268 }
 269
 270 type_init(pl031_register_types)