qemu/hw/timer/cmsdk-apb-dualtimer.c
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   1/*
   2 * ARM CMSDK APB dual-timer 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 dual-input timer" 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
  19#include "qemu/osdep.h"
  20#include "qemu/log.h"
  21#include "trace.h"
  22#include "qapi/error.h"
  23#include "qemu/main-loop.h"
  24#include "hw/sysbus.h"
  25#include "hw/registerfields.h"
  26#include "hw/timer/cmsdk-apb-dualtimer.h"
  27
  28REG32(TIMER1LOAD, 0x0)
  29REG32(TIMER1VALUE, 0x4)
  30REG32(TIMER1CONTROL, 0x8)
  31    FIELD(CONTROL, ONESHOT, 0, 1)
  32    FIELD(CONTROL, SIZE, 1, 1)
  33    FIELD(CONTROL, PRESCALE, 2, 2)
  34    FIELD(CONTROL, INTEN, 5, 1)
  35    FIELD(CONTROL, MODE, 6, 1)
  36    FIELD(CONTROL, ENABLE, 7, 1)
  37#define R_CONTROL_VALID_MASK (R_CONTROL_ONESHOT_MASK | R_CONTROL_SIZE_MASK | \
  38                              R_CONTROL_PRESCALE_MASK | R_CONTROL_INTEN_MASK | \
  39                              R_CONTROL_MODE_MASK | R_CONTROL_ENABLE_MASK)
  40REG32(TIMER1INTCLR, 0xc)
  41REG32(TIMER1RIS, 0x10)
  42REG32(TIMER1MIS, 0x14)
  43REG32(TIMER1BGLOAD, 0x18)
  44REG32(TIMER2LOAD, 0x20)
  45REG32(TIMER2VALUE, 0x24)
  46REG32(TIMER2CONTROL, 0x28)
  47REG32(TIMER2INTCLR, 0x2c)
  48REG32(TIMER2RIS, 0x30)
  49REG32(TIMER2MIS, 0x34)
  50REG32(TIMER2BGLOAD, 0x38)
  51REG32(TIMERITCR, 0xf00)
  52    FIELD(TIMERITCR, ENABLE, 0, 1)
  53#define R_TIMERITCR_VALID_MASK R_TIMERITCR_ENABLE_MASK
  54REG32(TIMERITOP, 0xf04)
  55    FIELD(TIMERITOP, TIMINT1, 0, 1)
  56    FIELD(TIMERITOP, TIMINT2, 1, 1)
  57#define R_TIMERITOP_VALID_MASK (R_TIMERITOP_TIMINT1_MASK | \
  58                                R_TIMERITOP_TIMINT2_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 int timer_id[] = {
  74    0x04, 0x00, 0x00, 0x00, /* PID4..PID7 */
  75    0x23, 0xb8, 0x1b, 0x00, /* PID0..PID3 */
  76    0x0d, 0xf0, 0x05, 0xb1, /* CID0..CID3 */
  77};
  78
  79static bool cmsdk_dualtimermod_intstatus(CMSDKAPBDualTimerModule *m)
  80{
  81    /* Return masked interrupt status for the timer module */
  82    return m->intstatus && (m->control & R_CONTROL_INTEN_MASK);
  83}
  84
  85static void cmsdk_apb_dualtimer_update(CMSDKAPBDualTimer *s)
  86{
  87    bool timint1, timint2, timintc;
  88
  89    if (s->timeritcr) {
  90        /* Integration test mode: outputs driven directly from TIMERITOP bits */
  91        timint1 = s->timeritop & R_TIMERITOP_TIMINT1_MASK;
  92        timint2 = s->timeritop & R_TIMERITOP_TIMINT2_MASK;
  93    } else {
  94        timint1 = cmsdk_dualtimermod_intstatus(&s->timermod[0]);
  95        timint2 = cmsdk_dualtimermod_intstatus(&s->timermod[1]);
  96    }
  97
  98    timintc = timint1 || timint2;
  99
 100    qemu_set_irq(s->timermod[0].timerint, timint1);
 101    qemu_set_irq(s->timermod[1].timerint, timint2);
 102    qemu_set_irq(s->timerintc, timintc);
 103}
 104
 105static void cmsdk_dualtimermod_write_control(CMSDKAPBDualTimerModule *m,
 106                                             uint32_t newctrl)
 107{
 108    /* Handle a write to the CONTROL register */
 109    uint32_t changed;
 110
 111    newctrl &= R_CONTROL_VALID_MASK;
 112
 113    changed = m->control ^ newctrl;
 114
 115    if (changed & ~newctrl & R_CONTROL_ENABLE_MASK) {
 116        /* ENABLE cleared, stop timer before any further changes */
 117        ptimer_stop(m->timer);
 118    }
 119
 120    if (changed & R_CONTROL_PRESCALE_MASK) {
 121        int divisor;
 122
 123        switch (FIELD_EX32(newctrl, CONTROL, PRESCALE)) {
 124        case 0:
 125            divisor = 1;
 126            break;
 127        case 1:
 128            divisor = 16;
 129            break;
 130        case 2:
 131            divisor = 256;
 132            break;
 133        case 3:
 134            /* UNDEFINED; complain, and arbitrarily treat like 2 */
 135            qemu_log_mask(LOG_GUEST_ERROR,
 136                          "CMSDK APB dual-timer: CONTROL.PRESCALE==0b11"
 137                          " is undefined behaviour\n");
 138            divisor = 256;
 139            break;
 140        default:
 141            g_assert_not_reached();
 142        }
 143        ptimer_set_freq(m->timer, m->parent->pclk_frq / divisor);
 144    }
 145
 146    if (changed & R_CONTROL_MODE_MASK) {
 147        uint32_t load;
 148        if (newctrl & R_CONTROL_MODE_MASK) {
 149            /* Periodic: the limit is the LOAD register value */
 150            load = m->load;
 151        } else {
 152            /* Free-running: counter wraps around */
 153            load = ptimer_get_limit(m->timer);
 154            if (!(m->control & R_CONTROL_SIZE_MASK)) {
 155                load = deposit32(m->load, 0, 16, load);
 156            }
 157            m->load = load;
 158            load = 0xffffffff;
 159        }
 160        if (!(m->control & R_CONTROL_SIZE_MASK)) {
 161            load &= 0xffff;
 162        }
 163        ptimer_set_limit(m->timer, load, 0);
 164    }
 165
 166    if (changed & R_CONTROL_SIZE_MASK) {
 167        /* Timer switched between 16 and 32 bit count */
 168        uint32_t value, load;
 169
 170        value = ptimer_get_count(m->timer);
 171        load = ptimer_get_limit(m->timer);
 172        if (newctrl & R_CONTROL_SIZE_MASK) {
 173            /* 16 -> 32, top half of VALUE is in struct field */
 174            value = deposit32(m->value, 0, 16, value);
 175        } else {
 176            /* 32 -> 16: save top half to struct field and truncate */
 177            m->value = value;
 178            value &= 0xffff;
 179        }
 180
 181        if (newctrl & R_CONTROL_MODE_MASK) {
 182            /* Periodic, timer limit has LOAD value */
 183            if (newctrl & R_CONTROL_SIZE_MASK) {
 184                load = deposit32(m->load, 0, 16, load);
 185            } else {
 186                m->load = load;
 187                load &= 0xffff;
 188            }
 189        } else {
 190            /* Free-running, timer limit is set to give wraparound */
 191            if (newctrl & R_CONTROL_SIZE_MASK) {
 192                load = 0xffffffff;
 193            } else {
 194                load = 0xffff;
 195            }
 196        }
 197        ptimer_set_count(m->timer, value);
 198        ptimer_set_limit(m->timer, load, 0);
 199    }
 200
 201    if (newctrl & R_CONTROL_ENABLE_MASK) {
 202        /*
 203         * ENABLE is set; start the timer after all other changes.
 204         * We start it even if the ENABLE bit didn't actually change,
 205         * in case the timer was an expired one-shot timer that has
 206         * now been changed into a free-running or periodic timer.
 207         */
 208        ptimer_run(m->timer, !!(newctrl & R_CONTROL_ONESHOT_MASK));
 209    }
 210
 211    m->control = newctrl;
 212}
 213
 214static uint64_t cmsdk_apb_dualtimer_read(void *opaque, hwaddr offset,
 215                                          unsigned size)
 216{
 217    CMSDKAPBDualTimer *s = CMSDK_APB_DUALTIMER(opaque);
 218    uint64_t r;
 219
 220    if (offset >= A_TIMERITCR) {
 221        switch (offset) {
 222        case A_TIMERITCR:
 223            r = s->timeritcr;
 224            break;
 225        case A_PID4 ... A_CID3:
 226            r = timer_id[(offset - A_PID4) / 4];
 227            break;
 228        default:
 229        bad_offset:
 230            qemu_log_mask(LOG_GUEST_ERROR,
 231                          "CMSDK APB dual-timer read: bad offset %x\n",
 232                          (int) offset);
 233            r = 0;
 234            break;
 235        }
 236    } else {
 237        int timer = offset >> 5;
 238        CMSDKAPBDualTimerModule *m;
 239
 240        if (timer >= ARRAY_SIZE(s->timermod)) {
 241            goto bad_offset;
 242        }
 243
 244        m = &s->timermod[timer];
 245
 246        switch (offset & 0x1F) {
 247        case A_TIMER1LOAD:
 248        case A_TIMER1BGLOAD:
 249            if (m->control & R_CONTROL_MODE_MASK) {
 250                /*
 251                 * Periodic: the ptimer limit is the LOAD register value, (or
 252                 * just the low 16 bits of it if the timer is in 16-bit mode)
 253                 */
 254                r = ptimer_get_limit(m->timer);
 255                if (!(m->control & R_CONTROL_SIZE_MASK)) {
 256                    r = deposit32(m->load, 0, 16, r);
 257                }
 258            } else {
 259                /* Free-running: LOAD register value is just in m->load */
 260                r = m->load;
 261            }
 262            break;
 263        case A_TIMER1VALUE:
 264            r = ptimer_get_count(m->timer);
 265            if (!(m->control & R_CONTROL_SIZE_MASK)) {
 266                r = deposit32(m->value, 0, 16, r);
 267            }
 268            break;
 269        case A_TIMER1CONTROL:
 270            r = m->control;
 271            break;
 272        case A_TIMER1RIS:
 273            r = m->intstatus;
 274            break;
 275        case A_TIMER1MIS:
 276            r = cmsdk_dualtimermod_intstatus(m);
 277            break;
 278        default:
 279            goto bad_offset;
 280        }
 281    }
 282
 283    trace_cmsdk_apb_dualtimer_read(offset, r, size);
 284    return r;
 285}
 286
 287static void cmsdk_apb_dualtimer_write(void *opaque, hwaddr offset,
 288                                       uint64_t value, unsigned size)
 289{
 290    CMSDKAPBDualTimer *s = CMSDK_APB_DUALTIMER(opaque);
 291
 292    trace_cmsdk_apb_dualtimer_write(offset, value, size);
 293
 294    if (offset >= A_TIMERITCR) {
 295        switch (offset) {
 296        case A_TIMERITCR:
 297            s->timeritcr = value & R_TIMERITCR_VALID_MASK;
 298            cmsdk_apb_dualtimer_update(s);
 299            break;
 300        case A_TIMERITOP:
 301            s->timeritop = value & R_TIMERITOP_VALID_MASK;
 302            cmsdk_apb_dualtimer_update(s);
 303            break;
 304        default:
 305        bad_offset:
 306            qemu_log_mask(LOG_GUEST_ERROR,
 307                          "CMSDK APB dual-timer write: bad offset %x\n",
 308                          (int) offset);
 309            break;
 310        }
 311    } else {
 312        int timer = offset >> 5;
 313        CMSDKAPBDualTimerModule *m;
 314
 315        if (timer >= ARRAY_SIZE(s->timermod)) {
 316            goto bad_offset;
 317        }
 318
 319        m = &s->timermod[timer];
 320
 321        switch (offset & 0x1F) {
 322        case A_TIMER1LOAD:
 323            /* Set the limit, and immediately reload the count from it */
 324            m->load = value;
 325            m->value = value;
 326            if (!(m->control & R_CONTROL_SIZE_MASK)) {
 327                value &= 0xffff;
 328            }
 329            if (!(m->control & R_CONTROL_MODE_MASK)) {
 330                /*
 331                 * In free-running mode this won't set the limit but will
 332                 * still change the current count value.
 333                 */
 334                ptimer_set_count(m->timer, value);
 335            } else {
 336                if (!value) {
 337                    ptimer_stop(m->timer);
 338                }
 339                ptimer_set_limit(m->timer, value, 1);
 340                if (value && (m->control & R_CONTROL_ENABLE_MASK)) {
 341                    /* Force possibly-expired oneshot timer to restart */
 342                    ptimer_run(m->timer, 1);
 343                }
 344            }
 345            break;
 346        case A_TIMER1BGLOAD:
 347            /* Set the limit, but not the current count */
 348            m->load = value;
 349            if (!(m->control & R_CONTROL_MODE_MASK)) {
 350                /* In free-running mode there is no limit */
 351                break;
 352            }
 353            if (!(m->control & R_CONTROL_SIZE_MASK)) {
 354                value &= 0xffff;
 355            }
 356            ptimer_set_limit(m->timer, value, 0);
 357            break;
 358        case A_TIMER1CONTROL:
 359            cmsdk_dualtimermod_write_control(m, value);
 360            cmsdk_apb_dualtimer_update(s);
 361            break;
 362        case A_TIMER1INTCLR:
 363            m->intstatus = 0;
 364            cmsdk_apb_dualtimer_update(s);
 365            break;
 366        default:
 367            goto bad_offset;
 368        }
 369    }
 370}
 371
 372static const MemoryRegionOps cmsdk_apb_dualtimer_ops = {
 373    .read = cmsdk_apb_dualtimer_read,
 374    .write = cmsdk_apb_dualtimer_write,
 375    .endianness = DEVICE_LITTLE_ENDIAN,
 376    /* byte/halfword accesses are just zero-padded on reads and writes */
 377    .impl.min_access_size = 4,
 378    .impl.max_access_size = 4,
 379    .valid.min_access_size = 1,
 380    .valid.max_access_size = 4,
 381};
 382
 383static void cmsdk_dualtimermod_tick(void *opaque)
 384{
 385    CMSDKAPBDualTimerModule *m = opaque;
 386
 387    m->intstatus = 1;
 388    cmsdk_apb_dualtimer_update(m->parent);
 389}
 390
 391static void cmsdk_dualtimermod_reset(CMSDKAPBDualTimerModule *m)
 392{
 393    m->control = R_CONTROL_INTEN_MASK;
 394    m->intstatus = 0;
 395    m->load = 0;
 396    m->value = 0xffffffff;
 397    ptimer_stop(m->timer);
 398    /*
 399     * We start in free-running mode, with VALUE at 0xffffffff, and
 400     * in 16-bit counter mode. This means that the ptimer count and
 401     * limit must both be set to 0xffff, so we wrap at 16 bits.
 402     */
 403    ptimer_set_limit(m->timer, 0xffff, 1);
 404    ptimer_set_freq(m->timer, m->parent->pclk_frq);
 405}
 406
 407static void cmsdk_apb_dualtimer_reset(DeviceState *dev)
 408{
 409    CMSDKAPBDualTimer *s = CMSDK_APB_DUALTIMER(dev);
 410    int i;
 411
 412    trace_cmsdk_apb_dualtimer_reset();
 413
 414    for (i = 0; i < ARRAY_SIZE(s->timermod); i++) {
 415        cmsdk_dualtimermod_reset(&s->timermod[i]);
 416    }
 417    s->timeritcr = 0;
 418    s->timeritop = 0;
 419}
 420
 421static void cmsdk_apb_dualtimer_init(Object *obj)
 422{
 423    SysBusDevice *sbd = SYS_BUS_DEVICE(obj);
 424    CMSDKAPBDualTimer *s = CMSDK_APB_DUALTIMER(obj);
 425    int i;
 426
 427    memory_region_init_io(&s->iomem, obj, &cmsdk_apb_dualtimer_ops,
 428                          s, "cmsdk-apb-dualtimer", 0x1000);
 429    sysbus_init_mmio(sbd, &s->iomem);
 430    sysbus_init_irq(sbd, &s->timerintc);
 431
 432    for (i = 0; i < ARRAY_SIZE(s->timermod); i++) {
 433        sysbus_init_irq(sbd, &s->timermod[i].timerint);
 434    }
 435}
 436
 437static void cmsdk_apb_dualtimer_realize(DeviceState *dev, Error **errp)
 438{
 439    CMSDKAPBDualTimer *s = CMSDK_APB_DUALTIMER(dev);
 440    int i;
 441
 442    if (s->pclk_frq == 0) {
 443        error_setg(errp, "CMSDK APB timer: pclk-frq property must be set");
 444        return;
 445    }
 446
 447    for (i = 0; i < ARRAY_SIZE(s->timermod); i++) {
 448        CMSDKAPBDualTimerModule *m = &s->timermod[i];
 449        QEMUBH *bh = qemu_bh_new(cmsdk_dualtimermod_tick, m);
 450
 451        m->parent = s;
 452        m->timer = ptimer_init(bh,
 453                               PTIMER_POLICY_WRAP_AFTER_ONE_PERIOD |
 454                               PTIMER_POLICY_TRIGGER_ONLY_ON_DECREMENT |
 455                               PTIMER_POLICY_NO_IMMEDIATE_RELOAD |
 456                               PTIMER_POLICY_NO_COUNTER_ROUND_DOWN);
 457    }
 458}
 459
 460static const VMStateDescription cmsdk_dualtimermod_vmstate = {
 461    .name = "cmsdk-apb-dualtimer-module",
 462    .version_id = 1,
 463    .minimum_version_id = 1,
 464    .fields = (VMStateField[]) {
 465        VMSTATE_PTIMER(timer, CMSDKAPBDualTimerModule),
 466        VMSTATE_UINT32(load, CMSDKAPBDualTimerModule),
 467        VMSTATE_UINT32(value, CMSDKAPBDualTimerModule),
 468        VMSTATE_UINT32(control, CMSDKAPBDualTimerModule),
 469        VMSTATE_UINT32(intstatus, CMSDKAPBDualTimerModule),
 470        VMSTATE_END_OF_LIST()
 471    }
 472};
 473
 474static const VMStateDescription cmsdk_apb_dualtimer_vmstate = {
 475    .name = "cmsdk-apb-dualtimer",
 476    .version_id = 1,
 477    .minimum_version_id = 1,
 478    .fields = (VMStateField[]) {
 479        VMSTATE_STRUCT_ARRAY(timermod, CMSDKAPBDualTimer,
 480                             CMSDK_APB_DUALTIMER_NUM_MODULES,
 481                             1, cmsdk_dualtimermod_vmstate,
 482                             CMSDKAPBDualTimerModule),
 483        VMSTATE_UINT32(timeritcr, CMSDKAPBDualTimer),
 484        VMSTATE_UINT32(timeritop, CMSDKAPBDualTimer),
 485        VMSTATE_END_OF_LIST()
 486    }
 487};
 488
 489static Property cmsdk_apb_dualtimer_properties[] = {
 490    DEFINE_PROP_UINT32("pclk-frq", CMSDKAPBDualTimer, pclk_frq, 0),
 491    DEFINE_PROP_END_OF_LIST(),
 492};
 493
 494static void cmsdk_apb_dualtimer_class_init(ObjectClass *klass, void *data)
 495{
 496    DeviceClass *dc = DEVICE_CLASS(klass);
 497
 498    dc->realize = cmsdk_apb_dualtimer_realize;
 499    dc->vmsd = &cmsdk_apb_dualtimer_vmstate;
 500    dc->reset = cmsdk_apb_dualtimer_reset;
 501    dc->props = cmsdk_apb_dualtimer_properties;
 502}
 503
 504static const TypeInfo cmsdk_apb_dualtimer_info = {
 505    .name = TYPE_CMSDK_APB_DUALTIMER,
 506    .parent = TYPE_SYS_BUS_DEVICE,
 507    .instance_size = sizeof(CMSDKAPBDualTimer),
 508    .instance_init = cmsdk_apb_dualtimer_init,
 509    .class_init = cmsdk_apb_dualtimer_class_init,
 510};
 511
 512static void cmsdk_apb_dualtimer_register_types(void)
 513{
 514    type_register_static(&cmsdk_apb_dualtimer_info);
 515}
 516
 517type_init(cmsdk_apb_dualtimer_register_types);
 518