qemu/hw/misc/edu.c
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   1/*
   2 * QEMU educational PCI device
   3 *
   4 * Copyright (c) 2012-2015 Jiri Slaby
   5 *
   6 * Permission is hereby granted, free of charge, to any person obtaining a
   7 * copy of this software and associated documentation files (the "Software"),
   8 * to deal in the Software without restriction, including without limitation
   9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10 * and/or sell copies of the Software, and to permit persons to whom the
  11 * Software is furnished to do so, subject to the following conditions:
  12 *
  13 * The above copyright notice and this permission notice shall be included in
  14 * all copies or substantial portions of the Software.
  15 *
  16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  19 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22 * DEALINGS IN THE SOFTWARE.
  23 */
  24
  25#include "qemu/osdep.h"
  26#include "qemu/units.h"
  27#include "hw/pci/pci.h"
  28#include "hw/hw.h"
  29#include "hw/pci/msi.h"
  30#include "qemu/timer.h"
  31#include "qom/object.h"
  32#include "qemu/main-loop.h" /* iothread mutex */
  33#include "qemu/module.h"
  34#include "qapi/visitor.h"
  35
  36#define TYPE_PCI_EDU_DEVICE "edu"
  37typedef struct EduState EduState;
  38DECLARE_INSTANCE_CHECKER(EduState, EDU,
  39                         TYPE_PCI_EDU_DEVICE)
  40
  41#define FACT_IRQ        0x00000001
  42#define DMA_IRQ         0x00000100
  43
  44#define DMA_START       0x40000
  45#define DMA_SIZE        4096
  46
  47struct EduState {
  48    PCIDevice pdev;
  49    MemoryRegion mmio;
  50
  51    QemuThread thread;
  52    QemuMutex thr_mutex;
  53    QemuCond thr_cond;
  54    bool stopping;
  55
  56    uint32_t addr4;
  57    uint32_t fact;
  58#define EDU_STATUS_COMPUTING    0x01
  59#define EDU_STATUS_IRQFACT      0x80
  60    uint32_t status;
  61
  62    uint32_t irq_status;
  63
  64#define EDU_DMA_RUN             0x1
  65#define EDU_DMA_DIR(cmd)        (((cmd) & 0x2) >> 1)
  66# define EDU_DMA_FROM_PCI       0
  67# define EDU_DMA_TO_PCI         1
  68#define EDU_DMA_IRQ             0x4
  69    struct dma_state {
  70        dma_addr_t src;
  71        dma_addr_t dst;
  72        dma_addr_t cnt;
  73        dma_addr_t cmd;
  74    } dma;
  75    QEMUTimer dma_timer;
  76    char dma_buf[DMA_SIZE];
  77    uint64_t dma_mask;
  78};
  79
  80static bool edu_msi_enabled(EduState *edu)
  81{
  82    return msi_enabled(&edu->pdev);
  83}
  84
  85static void edu_raise_irq(EduState *edu, uint32_t val)
  86{
  87    edu->irq_status |= val;
  88    if (edu->irq_status) {
  89        if (edu_msi_enabled(edu)) {
  90            msi_notify(&edu->pdev, 0);
  91        } else {
  92            pci_set_irq(&edu->pdev, 1);
  93        }
  94    }
  95}
  96
  97static void edu_lower_irq(EduState *edu, uint32_t val)
  98{
  99    edu->irq_status &= ~val;
 100
 101    if (!edu->irq_status && !edu_msi_enabled(edu)) {
 102        pci_set_irq(&edu->pdev, 0);
 103    }
 104}
 105
 106static bool within(uint64_t addr, uint64_t start, uint64_t end)
 107{
 108    return start <= addr && addr < end;
 109}
 110
 111static void edu_check_range(uint64_t addr, uint64_t size1, uint64_t start,
 112                uint64_t size2)
 113{
 114    uint64_t end1 = addr + size1;
 115    uint64_t end2 = start + size2;
 116
 117    if (within(addr, start, end2) &&
 118            end1 > addr && within(end1, start, end2)) {
 119        return;
 120    }
 121
 122    hw_error("EDU: DMA range 0x%016"PRIx64"-0x%016"PRIx64
 123             " out of bounds (0x%016"PRIx64"-0x%016"PRIx64")!",
 124            addr, end1 - 1, start, end2 - 1);
 125}
 126
 127static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
 128{
 129    dma_addr_t res = addr & edu->dma_mask;
 130
 131    if (addr != res) {
 132        printf("EDU: clamping DMA %#.16"PRIx64" to %#.16"PRIx64"!\n", addr, res);
 133    }
 134
 135    return res;
 136}
 137
 138static void edu_dma_timer(void *opaque)
 139{
 140    EduState *edu = opaque;
 141    bool raise_irq = false;
 142
 143    if (!(edu->dma.cmd & EDU_DMA_RUN)) {
 144        return;
 145    }
 146
 147    if (EDU_DMA_DIR(edu->dma.cmd) == EDU_DMA_FROM_PCI) {
 148        uint64_t dst = edu->dma.dst;
 149        edu_check_range(dst, edu->dma.cnt, DMA_START, DMA_SIZE);
 150        dst -= DMA_START;
 151        pci_dma_read(&edu->pdev, edu_clamp_addr(edu, edu->dma.src),
 152                edu->dma_buf + dst, edu->dma.cnt);
 153    } else {
 154        uint64_t src = edu->dma.src;
 155        edu_check_range(src, edu->dma.cnt, DMA_START, DMA_SIZE);
 156        src -= DMA_START;
 157        pci_dma_write(&edu->pdev, edu_clamp_addr(edu, edu->dma.dst),
 158                edu->dma_buf + src, edu->dma.cnt);
 159    }
 160
 161    edu->dma.cmd &= ~EDU_DMA_RUN;
 162    if (edu->dma.cmd & EDU_DMA_IRQ) {
 163        raise_irq = true;
 164    }
 165
 166    if (raise_irq) {
 167        edu_raise_irq(edu, DMA_IRQ);
 168    }
 169}
 170
 171static void dma_rw(EduState *edu, bool write, dma_addr_t *val, dma_addr_t *dma,
 172                bool timer)
 173{
 174    if (write && (edu->dma.cmd & EDU_DMA_RUN)) {
 175        return;
 176    }
 177
 178    if (write) {
 179        *dma = *val;
 180    } else {
 181        *val = *dma;
 182    }
 183
 184    if (timer) {
 185        timer_mod(&edu->dma_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 100);
 186    }
 187}
 188
 189static uint64_t edu_mmio_read(void *opaque, hwaddr addr, unsigned size)
 190{
 191    EduState *edu = opaque;
 192    uint64_t val = ~0ULL;
 193
 194    if (addr < 0x80 && size != 4) {
 195        return val;
 196    }
 197
 198    if (addr >= 0x80 && size != 4 && size != 8) {
 199        return val;
 200    }
 201
 202    switch (addr) {
 203    case 0x00:
 204        val = 0x010000edu;
 205        break;
 206    case 0x04:
 207        val = edu->addr4;
 208        break;
 209    case 0x08:
 210        qemu_mutex_lock(&edu->thr_mutex);
 211        val = edu->fact;
 212        qemu_mutex_unlock(&edu->thr_mutex);
 213        break;
 214    case 0x20:
 215        val = qatomic_read(&edu->status);
 216        break;
 217    case 0x24:
 218        val = edu->irq_status;
 219        break;
 220    case 0x80:
 221        dma_rw(edu, false, &val, &edu->dma.src, false);
 222        break;
 223    case 0x88:
 224        dma_rw(edu, false, &val, &edu->dma.dst, false);
 225        break;
 226    case 0x90:
 227        dma_rw(edu, false, &val, &edu->dma.cnt, false);
 228        break;
 229    case 0x98:
 230        dma_rw(edu, false, &val, &edu->dma.cmd, false);
 231        break;
 232    }
 233
 234    return val;
 235}
 236
 237static void edu_mmio_write(void *opaque, hwaddr addr, uint64_t val,
 238                unsigned size)
 239{
 240    EduState *edu = opaque;
 241
 242    if (addr < 0x80 && size != 4) {
 243        return;
 244    }
 245
 246    if (addr >= 0x80 && size != 4 && size != 8) {
 247        return;
 248    }
 249
 250    switch (addr) {
 251    case 0x04:
 252        edu->addr4 = ~val;
 253        break;
 254    case 0x08:
 255        if (qatomic_read(&edu->status) & EDU_STATUS_COMPUTING) {
 256            break;
 257        }
 258        /* EDU_STATUS_COMPUTING cannot go 0->1 concurrently, because it is only
 259         * set in this function and it is under the iothread mutex.
 260         */
 261        qemu_mutex_lock(&edu->thr_mutex);
 262        edu->fact = val;
 263        qatomic_or(&edu->status, EDU_STATUS_COMPUTING);
 264        qemu_cond_signal(&edu->thr_cond);
 265        qemu_mutex_unlock(&edu->thr_mutex);
 266        break;
 267    case 0x20:
 268        if (val & EDU_STATUS_IRQFACT) {
 269            qatomic_or(&edu->status, EDU_STATUS_IRQFACT);
 270        } else {
 271            qatomic_and(&edu->status, ~EDU_STATUS_IRQFACT);
 272        }
 273        break;
 274    case 0x60:
 275        edu_raise_irq(edu, val);
 276        break;
 277    case 0x64:
 278        edu_lower_irq(edu, val);
 279        break;
 280    case 0x80:
 281        dma_rw(edu, true, &val, &edu->dma.src, false);
 282        break;
 283    case 0x88:
 284        dma_rw(edu, true, &val, &edu->dma.dst, false);
 285        break;
 286    case 0x90:
 287        dma_rw(edu, true, &val, &edu->dma.cnt, false);
 288        break;
 289    case 0x98:
 290        if (!(val & EDU_DMA_RUN)) {
 291            break;
 292        }
 293        dma_rw(edu, true, &val, &edu->dma.cmd, true);
 294        break;
 295    }
 296}
 297
 298static const MemoryRegionOps edu_mmio_ops = {
 299    .read = edu_mmio_read,
 300    .write = edu_mmio_write,
 301    .endianness = DEVICE_NATIVE_ENDIAN,
 302    .valid = {
 303        .min_access_size = 4,
 304        .max_access_size = 8,
 305    },
 306    .impl = {
 307        .min_access_size = 4,
 308        .max_access_size = 8,
 309    },
 310
 311};
 312
 313/*
 314 * We purposely use a thread, so that users are forced to wait for the status
 315 * register.
 316 */
 317static void *edu_fact_thread(void *opaque)
 318{
 319    EduState *edu = opaque;
 320
 321    while (1) {
 322        uint32_t val, ret = 1;
 323
 324        qemu_mutex_lock(&edu->thr_mutex);
 325        while ((qatomic_read(&edu->status) & EDU_STATUS_COMPUTING) == 0 &&
 326                        !edu->stopping) {
 327            qemu_cond_wait(&edu->thr_cond, &edu->thr_mutex);
 328        }
 329
 330        if (edu->stopping) {
 331            qemu_mutex_unlock(&edu->thr_mutex);
 332            break;
 333        }
 334
 335        val = edu->fact;
 336        qemu_mutex_unlock(&edu->thr_mutex);
 337
 338        while (val > 0) {
 339            ret *= val--;
 340        }
 341
 342        /*
 343         * We should sleep for a random period here, so that students are
 344         * forced to check the status properly.
 345         */
 346
 347        qemu_mutex_lock(&edu->thr_mutex);
 348        edu->fact = ret;
 349        qemu_mutex_unlock(&edu->thr_mutex);
 350        qatomic_and(&edu->status, ~EDU_STATUS_COMPUTING);
 351
 352        if (qatomic_read(&edu->status) & EDU_STATUS_IRQFACT) {
 353            qemu_mutex_lock_iothread();
 354            edu_raise_irq(edu, FACT_IRQ);
 355            qemu_mutex_unlock_iothread();
 356        }
 357    }
 358
 359    return NULL;
 360}
 361
 362static void pci_edu_realize(PCIDevice *pdev, Error **errp)
 363{
 364    EduState *edu = EDU(pdev);
 365    uint8_t *pci_conf = pdev->config;
 366
 367    pci_config_set_interrupt_pin(pci_conf, 1);
 368
 369    if (msi_init(pdev, 0, 1, true, false, errp)) {
 370        return;
 371    }
 372
 373    timer_init_ms(&edu->dma_timer, QEMU_CLOCK_VIRTUAL, edu_dma_timer, edu);
 374
 375    qemu_mutex_init(&edu->thr_mutex);
 376    qemu_cond_init(&edu->thr_cond);
 377    qemu_thread_create(&edu->thread, "edu", edu_fact_thread,
 378                       edu, QEMU_THREAD_JOINABLE);
 379
 380    memory_region_init_io(&edu->mmio, OBJECT(edu), &edu_mmio_ops, edu,
 381                    "edu-mmio", 1 * MiB);
 382    pci_register_bar(pdev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &edu->mmio);
 383}
 384
 385static void pci_edu_uninit(PCIDevice *pdev)
 386{
 387    EduState *edu = EDU(pdev);
 388
 389    qemu_mutex_lock(&edu->thr_mutex);
 390    edu->stopping = true;
 391    qemu_mutex_unlock(&edu->thr_mutex);
 392    qemu_cond_signal(&edu->thr_cond);
 393    qemu_thread_join(&edu->thread);
 394
 395    qemu_cond_destroy(&edu->thr_cond);
 396    qemu_mutex_destroy(&edu->thr_mutex);
 397
 398    timer_del(&edu->dma_timer);
 399    msi_uninit(pdev);
 400}
 401
 402static void edu_instance_init(Object *obj)
 403{
 404    EduState *edu = EDU(obj);
 405
 406    edu->dma_mask = (1UL << 28) - 1;
 407    object_property_add_uint64_ptr(obj, "dma_mask",
 408                                   &edu->dma_mask, OBJ_PROP_FLAG_READWRITE);
 409}
 410
 411static void edu_class_init(ObjectClass *class, void *data)
 412{
 413    DeviceClass *dc = DEVICE_CLASS(class);
 414    PCIDeviceClass *k = PCI_DEVICE_CLASS(class);
 415
 416    k->realize = pci_edu_realize;
 417    k->exit = pci_edu_uninit;
 418    k->vendor_id = PCI_VENDOR_ID_QEMU;
 419    k->device_id = 0x11e8;
 420    k->revision = 0x10;
 421    k->class_id = PCI_CLASS_OTHERS;
 422    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 423}
 424
 425static void pci_edu_register_types(void)
 426{
 427    static InterfaceInfo interfaces[] = {
 428        { INTERFACE_CONVENTIONAL_PCI_DEVICE },
 429        { },
 430    };
 431    static const TypeInfo edu_info = {
 432        .name          = TYPE_PCI_EDU_DEVICE,
 433        .parent        = TYPE_PCI_DEVICE,
 434        .instance_size = sizeof(EduState),
 435        .instance_init = edu_instance_init,
 436        .class_init    = edu_class_init,
 437        .interfaces = interfaces,
 438    };
 439
 440    type_register_static(&edu_info);
 441}
 442type_init(pci_edu_register_types)
 443