qemu/hw/watchdog/cmsdk-apb-watchdog.c
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   1/*
   2 * ARM CMSDK APB watchdog emulation
   3 *
   4 * Copyright (c) 2018 Linaro Limited
   5 * Written by Peter Maydell
   6 *
   7 *  This program is free software; you can redistribute it and/or modify
   8 *  it under the terms of the GNU General Public License version 2 or
   9 *  (at your option) any later version.
  10 */
  11
  12/*
  13 * This is a model of the "APB watchdog" which is part of the Cortex-M
  14 * System Design Kit (CMSDK) and documented in the Cortex-M System
  15 * Design Kit Technical Reference Manual (ARM DDI0479C):
  16 * https://developer.arm.com/products/system-design/system-design-kits/cortex-m-system-design-kit
  17 *
  18 * We also support the variant of this device found in the TI
  19 * Stellaris/Luminary boards and documented in:
  20 * http://www.ti.com/lit/ds/symlink/lm3s6965.pdf
  21 */
  22
  23#include "qemu/osdep.h"
  24#include "qemu/log.h"
  25#include "trace.h"
  26#include "qapi/error.h"
  27#include "qemu/module.h"
  28#include "sysemu/watchdog.h"
  29#include "hw/sysbus.h"
  30#include "hw/irq.h"
  31#include "hw/qdev-properties.h"
  32#include "hw/registerfields.h"
  33#include "hw/qdev-clock.h"
  34#include "hw/watchdog/cmsdk-apb-watchdog.h"
  35#include "migration/vmstate.h"
  36
  37REG32(WDOGLOAD, 0x0)
  38REG32(WDOGVALUE, 0x4)
  39REG32(WDOGCONTROL, 0x8)
  40    FIELD(WDOGCONTROL, INTEN, 0, 1)
  41    FIELD(WDOGCONTROL, RESEN, 1, 1)
  42#define R_WDOGCONTROL_VALID_MASK (R_WDOGCONTROL_INTEN_MASK | \
  43                                  R_WDOGCONTROL_RESEN_MASK)
  44REG32(WDOGINTCLR, 0xc)
  45REG32(WDOGRIS, 0x10)
  46    FIELD(WDOGRIS, INT, 0, 1)
  47REG32(WDOGMIS, 0x14)
  48REG32(WDOGTEST, 0x418) /* only in Stellaris/Luminary version of the device */
  49REG32(WDOGLOCK, 0xc00)
  50#define WDOG_UNLOCK_VALUE 0x1ACCE551
  51REG32(WDOGITCR, 0xf00)
  52    FIELD(WDOGITCR, ENABLE, 0, 1)
  53#define R_WDOGITCR_VALID_MASK R_WDOGITCR_ENABLE_MASK
  54REG32(WDOGITOP, 0xf04)
  55    FIELD(WDOGITOP, WDOGRES, 0, 1)
  56    FIELD(WDOGITOP, WDOGINT, 1, 1)
  57#define R_WDOGITOP_VALID_MASK (R_WDOGITOP_WDOGRES_MASK | \
  58                               R_WDOGITOP_WDOGINT_MASK)
  59REG32(PID4, 0xfd0)
  60REG32(PID5, 0xfd4)
  61REG32(PID6, 0xfd8)
  62REG32(PID7, 0xfdc)
  63REG32(PID0, 0xfe0)
  64REG32(PID1, 0xfe4)
  65REG32(PID2, 0xfe8)
  66REG32(PID3, 0xfec)
  67REG32(CID0, 0xff0)
  68REG32(CID1, 0xff4)
  69REG32(CID2, 0xff8)
  70REG32(CID3, 0xffc)
  71
  72/* PID/CID values */
  73static const uint32_t cmsdk_apb_watchdog_id[] = {
  74    0x04, 0x00, 0x00, 0x00, /* PID4..PID7 */
  75    0x24, 0xb8, 0x1b, 0x00, /* PID0..PID3 */
  76    0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
  77};
  78
  79static const uint32_t luminary_watchdog_id[] = {
  80    0x00, 0x00, 0x00, 0x00, /* PID4..PID7 */
  81    0x05, 0x18, 0x18, 0x01, /* PID0..PID3 */
  82    0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
  83};
  84
  85static bool cmsdk_apb_watchdog_intstatus(CMSDKAPBWatchdog *s)
  86{
  87    /* Return masked interrupt status */
  88    return s->intstatus && (s->control & R_WDOGCONTROL_INTEN_MASK);
  89}
  90
  91static bool cmsdk_apb_watchdog_resetstatus(CMSDKAPBWatchdog *s)
  92{
  93    /* Return masked reset status */
  94    return s->resetstatus && (s->control & R_WDOGCONTROL_RESEN_MASK);
  95}
  96
  97static void cmsdk_apb_watchdog_update(CMSDKAPBWatchdog *s)
  98{
  99    bool wdogint;
 100    bool wdogres;
 101
 102    if (s->itcr) {
 103        /*
 104         * Not checking that !s->is_luminary since s->itcr can't be written
 105         * when s->is_luminary in the first place.
 106         */
 107        wdogint = s->itop & R_WDOGITOP_WDOGINT_MASK;
 108        wdogres = s->itop & R_WDOGITOP_WDOGRES_MASK;
 109    } else {
 110        wdogint = cmsdk_apb_watchdog_intstatus(s);
 111        wdogres = cmsdk_apb_watchdog_resetstatus(s);
 112    }
 113
 114    qemu_set_irq(s->wdogint, wdogint);
 115    if (wdogres) {
 116        watchdog_perform_action();
 117    }
 118}
 119
 120static uint64_t cmsdk_apb_watchdog_read(void *opaque, hwaddr offset,
 121                                        unsigned size)
 122{
 123    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(opaque);
 124    uint64_t r;
 125
 126    switch (offset) {
 127    case A_WDOGLOAD:
 128        r = ptimer_get_limit(s->timer);
 129        break;
 130    case A_WDOGVALUE:
 131        r = ptimer_get_count(s->timer);
 132        break;
 133    case A_WDOGCONTROL:
 134        r = s->control;
 135        break;
 136    case A_WDOGRIS:
 137        r = s->intstatus;
 138        break;
 139    case A_WDOGMIS:
 140        r = cmsdk_apb_watchdog_intstatus(s);
 141        break;
 142    case A_WDOGLOCK:
 143        r = s->lock;
 144        break;
 145    case A_WDOGITCR:
 146        if (s->is_luminary) {
 147            goto bad_offset;
 148        }
 149        r = s->itcr;
 150        break;
 151    case A_PID4 ... A_CID3:
 152        r = s->id[(offset - A_PID4) / 4];
 153        break;
 154    case A_WDOGINTCLR:
 155    case A_WDOGITOP:
 156        if (s->is_luminary) {
 157            goto bad_offset;
 158        }
 159        qemu_log_mask(LOG_GUEST_ERROR,
 160                      "CMSDK APB watchdog read: read of WO offset %x\n",
 161                      (int)offset);
 162        r = 0;
 163        break;
 164    case A_WDOGTEST:
 165        if (!s->is_luminary) {
 166            goto bad_offset;
 167        }
 168        qemu_log_mask(LOG_UNIMP,
 169                      "Luminary watchdog read: stall not implemented\n");
 170        r = 0;
 171        break;
 172    default:
 173bad_offset:
 174        qemu_log_mask(LOG_GUEST_ERROR,
 175                      "CMSDK APB watchdog read: bad offset %x\n", (int)offset);
 176        r = 0;
 177        break;
 178    }
 179    trace_cmsdk_apb_watchdog_read(offset, r, size);
 180    return r;
 181}
 182
 183static void cmsdk_apb_watchdog_write(void *opaque, hwaddr offset,
 184                                     uint64_t value, unsigned size)
 185{
 186    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(opaque);
 187
 188    trace_cmsdk_apb_watchdog_write(offset, value, size);
 189
 190    if (s->lock && offset != A_WDOGLOCK) {
 191        /* Write access is disabled via WDOGLOCK */
 192        qemu_log_mask(LOG_GUEST_ERROR,
 193                      "CMSDK APB watchdog write: write to locked watchdog\n");
 194        return;
 195    }
 196
 197    switch (offset) {
 198    case A_WDOGLOAD:
 199        /*
 200         * Reset the load value and the current count, and make sure
 201         * we're counting.
 202         */
 203        ptimer_transaction_begin(s->timer);
 204        ptimer_set_limit(s->timer, value, 1);
 205        ptimer_run(s->timer, 0);
 206        ptimer_transaction_commit(s->timer);
 207        break;
 208    case A_WDOGCONTROL:
 209        if (s->is_luminary && 0 != (R_WDOGCONTROL_INTEN_MASK & s->control)) {
 210            /*
 211             * The Luminary version of this device ignores writes to
 212             * this register after the guest has enabled interrupts
 213             * (so they can only be disabled again via reset).
 214             */
 215            break;
 216        }
 217        s->control = value & R_WDOGCONTROL_VALID_MASK;
 218        cmsdk_apb_watchdog_update(s);
 219        break;
 220    case A_WDOGINTCLR:
 221        s->intstatus = 0;
 222        ptimer_transaction_begin(s->timer);
 223        ptimer_set_count(s->timer, ptimer_get_limit(s->timer));
 224        ptimer_transaction_commit(s->timer);
 225        cmsdk_apb_watchdog_update(s);
 226        break;
 227    case A_WDOGLOCK:
 228        s->lock = (value != WDOG_UNLOCK_VALUE);
 229        trace_cmsdk_apb_watchdog_lock(s->lock);
 230        break;
 231    case A_WDOGITCR:
 232        if (s->is_luminary) {
 233            goto bad_offset;
 234        }
 235        s->itcr = value & R_WDOGITCR_VALID_MASK;
 236        cmsdk_apb_watchdog_update(s);
 237        break;
 238    case A_WDOGITOP:
 239        if (s->is_luminary) {
 240            goto bad_offset;
 241        }
 242        s->itop = value & R_WDOGITOP_VALID_MASK;
 243        cmsdk_apb_watchdog_update(s);
 244        break;
 245    case A_WDOGVALUE:
 246    case A_WDOGRIS:
 247    case A_WDOGMIS:
 248    case A_PID4 ... A_CID3:
 249        qemu_log_mask(LOG_GUEST_ERROR,
 250                      "CMSDK APB watchdog write: write to RO offset 0x%x\n",
 251                      (int)offset);
 252        break;
 253    case A_WDOGTEST:
 254        if (!s->is_luminary) {
 255            goto bad_offset;
 256        }
 257        qemu_log_mask(LOG_UNIMP,
 258                      "Luminary watchdog write: stall not implemented\n");
 259        break;
 260    default:
 261bad_offset:
 262        qemu_log_mask(LOG_GUEST_ERROR,
 263                      "CMSDK APB watchdog write: bad offset 0x%x\n",
 264                      (int)offset);
 265        break;
 266    }
 267}
 268
 269static const MemoryRegionOps cmsdk_apb_watchdog_ops = {
 270    .read = cmsdk_apb_watchdog_read,
 271    .write = cmsdk_apb_watchdog_write,
 272    .endianness = DEVICE_LITTLE_ENDIAN,
 273    /* byte/halfword accesses are just zero-padded on reads and writes */
 274    .impl.min_access_size = 4,
 275    .impl.max_access_size = 4,
 276    .valid.min_access_size = 1,
 277    .valid.max_access_size = 4,
 278};
 279
 280static void cmsdk_apb_watchdog_tick(void *opaque)
 281{
 282    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(opaque);
 283
 284    if (!s->intstatus) {
 285        /* Count expired for the first time: raise interrupt */
 286        s->intstatus = R_WDOGRIS_INT_MASK;
 287    } else {
 288        /* Count expired for the second time: raise reset and stop clock */
 289        s->resetstatus = 1;
 290        ptimer_stop(s->timer);
 291    }
 292    cmsdk_apb_watchdog_update(s);
 293}
 294
 295static void cmsdk_apb_watchdog_reset(DeviceState *dev)
 296{
 297    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(dev);
 298
 299    trace_cmsdk_apb_watchdog_reset();
 300    s->control = 0;
 301    s->intstatus = 0;
 302    s->lock = 0;
 303    s->itcr = 0;
 304    s->itop = 0;
 305    s->resetstatus = 0;
 306    /* Set the limit and the count */
 307    ptimer_transaction_begin(s->timer);
 308    ptimer_set_limit(s->timer, 0xffffffff, 1);
 309    ptimer_run(s->timer, 0);
 310    ptimer_transaction_commit(s->timer);
 311}
 312
 313static void cmsdk_apb_watchdog_clk_update(void *opaque, ClockEvent event)
 314{
 315    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(opaque);
 316
 317    ptimer_transaction_begin(s->timer);
 318    ptimer_set_period_from_clock(s->timer, s->wdogclk, 1);
 319    ptimer_transaction_commit(s->timer);
 320}
 321
 322static void cmsdk_apb_watchdog_init(Object *obj)
 323{
 324    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 325    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(obj);
 326
 327    memory_region_init_io(&s->iomem, obj, &cmsdk_apb_watchdog_ops,
 328                          s, "cmsdk-apb-watchdog", 0x1000);
 329    sysbus_init_mmio(sbd, &s->iomem);
 330    sysbus_init_irq(sbd, &s->wdogint);
 331    s->wdogclk = qdev_init_clock_in(DEVICE(s), "WDOGCLK",
 332                                    cmsdk_apb_watchdog_clk_update, s,
 333                                    ClockUpdate);
 334
 335    s->is_luminary = false;
 336    s->id = cmsdk_apb_watchdog_id;
 337}
 338
 339static void cmsdk_apb_watchdog_realize(DeviceState *dev, Error **errp)
 340{
 341    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(dev);
 342
 343    if (!clock_has_source(s->wdogclk)) {
 344        error_setg(errp,
 345                   "CMSDK APB watchdog: WDOGCLK clock must be connected");
 346        return;
 347    }
 348
 349    s->timer = ptimer_init(cmsdk_apb_watchdog_tick, s,
 350                           PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD |
 351                           PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT |
 352                           PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
 353                           PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);
 354
 355    ptimer_transaction_begin(s->timer);
 356    ptimer_set_period_from_clock(s->timer, s->wdogclk, 1);
 357    ptimer_transaction_commit(s->timer);
 358}
 359
 360static const VMStateDescription cmsdk_apb_watchdog_vmstate = {
 361    .name = "cmsdk-apb-watchdog",
 362    .version_id = 2,
 363    .minimum_version_id = 2,
 364    .fields = (VMStateField[]) {
 365        VMSTATE_CLOCK(wdogclk, CMSDKAPBWatchdog),
 366        VMSTATE_PTIMER(timer, CMSDKAPBWatchdog),
 367        VMSTATE_UINT32(control, CMSDKAPBWatchdog),
 368        VMSTATE_UINT32(intstatus, CMSDKAPBWatchdog),
 369        VMSTATE_UINT32(lock, CMSDKAPBWatchdog),
 370        VMSTATE_UINT32(itcr, CMSDKAPBWatchdog),
 371        VMSTATE_UINT32(itop, CMSDKAPBWatchdog),
 372        VMSTATE_UINT32(resetstatus, CMSDKAPBWatchdog),
 373        VMSTATE_END_OF_LIST()
 374    }
 375};
 376
 377static void cmsdk_apb_watchdog_class_init(ObjectClass *klass, void *data)
 378{
 379    DeviceClass *dc = DEVICE_CLASS(klass);
 380
 381    dc->realize = cmsdk_apb_watchdog_realize;
 382    dc->vmsd = &cmsdk_apb_watchdog_vmstate;
 383    dc->reset = cmsdk_apb_watchdog_reset;
 384}
 385
 386static const TypeInfo cmsdk_apb_watchdog_info = {
 387    .name = TYPE_CMSDK_APB_WATCHDOG,
 388    .parent = TYPE_SYS_BUS_DEVICE,
 389    .instance_size = sizeof(CMSDKAPBWatchdog),
 390    .instance_init = cmsdk_apb_watchdog_init,
 391    .class_init = cmsdk_apb_watchdog_class_init,
 392};
 393
 394static void luminary_watchdog_init(Object *obj)
 395{
 396    CMSDKAPBWatchdog *s = CMSDK_APB_WATCHDOG(obj);
 397
 398    s->is_luminary = true;
 399    s->id = luminary_watchdog_id;
 400}
 401
 402static const TypeInfo luminary_watchdog_info = {
 403    .name = TYPE_LUMINARY_WATCHDOG,
 404    .parent = TYPE_CMSDK_APB_WATCHDOG,
 405    .instance_init = luminary_watchdog_init
 406};
 407
 408static void cmsdk_apb_watchdog_register_types(void)
 409{
 410    type_register_static(&cmsdk_apb_watchdog_info);
 411    type_register_static(&luminary_watchdog_info);
 412}
 413
 414type_init(cmsdk_apb_watchdog_register_types);
 415