hw/misc/edu.c

   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 "hw/pci/pci.h"
  27 #include "hw/pci/msi.h"
  28 #include "qemu/timer.h"
  29 #include "qemu/main-loop.h" /* iothread mutex */
  30 #include "qapi/visitor.h"
  31
  32 #define EDU(obj)        OBJECT_CHECK(EduState, obj, "edu")
  33
  34 #define FACT_IRQ        0x00000001
  35 #define DMA_IRQ         0x00000100
  36
  37 #define DMA_START       0x40000
  38 #define DMA_SIZE        4096
  39
  40 typedef struct {
  41     PCIDevice pdev;
  42     MemoryRegion mmio;
  43
  44     QemuThread thread;
  45     QemuMutex thr_mutex;
  46     QemuCond thr_cond;
  47     bool stopping;
  48
  49     uint32_t addr4;
  50     uint32_t fact;
  51 #define EDU_STATUS_COMPUTING    0x01
  52 #define EDU_STATUS_IRQFACT      0x80
  53     uint32_t status;
  54
  55     uint32_t irq_status;
  56
  57 #define EDU_DMA_RUN             0x1
  58 #define EDU_DMA_DIR(cmd)        (((cmd) & 0x2) >> 1)
  59 # define EDU_DMA_FROM_PCI       0
  60 # define EDU_DMA_TO_PCI         1
  61 #define EDU_DMA_IRQ             0x4
  62     struct dma_state {
  63         dma_addr_t src;
  64         dma_addr_t dst;
  65         dma_addr_t cnt;
  66         dma_addr_t cmd;
  67     } dma;
  68     QEMUTimer dma_timer;
  69     char dma_buf[DMA_SIZE];
  70     uint64_t dma_mask;
  71 } EduState;
  72
  73 static bool edu_msi_enabled(EduState *edu)
  74 {
  75     return msi_enabled(&edu->pdev);
  76 }
  77
  78 static void edu_raise_irq(EduState *edu, uint32_t val)
  79 {
  80     edu->irq_status |= val;
  81     if (edu->irq_status) {
  82         if (edu_msi_enabled(edu)) {
  83             msi_notify(&edu->pdev, 0);
  84         } else {
  85             pci_set_irq(&edu->pdev, 1);
  86         }
  87     }
  88 }
  89
  90 static void edu_lower_irq(EduState *edu, uint32_t val)
  91 {
  92     edu->irq_status &= ~val;
  93
  94     if (!edu->irq_status && !edu_msi_enabled(edu)) {
  95         pci_set_irq(&edu->pdev, 0);
  96     }
  97 }
  98
  99 static bool within(uint32_t addr, uint32_t start, uint32_t end)
 100 {
 101     return start <= addr && addr < end;
 102 }
 103
 104 static void edu_check_range(uint32_t addr, uint32_t size1, uint32_t start,
 105                 uint32_t size2)
 106 {
 107     uint32_t end1 = addr + size1;
 108     uint32_t end2 = start + size2;
 109
 110     if (within(addr, start, end2) &&
 111             end1 > addr && within(end1, start, end2)) {
 112         return;
 113     }
 114
 115     hw_error("EDU: DMA range 0x%.8x-0x%.8x out of bounds (0x%.8x-0x%.8x)!",
 116             addr, end1 - 1, start, end2 - 1);
 117 }
 118
 119 static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
 120 {
 121     dma_addr_t res = addr & edu->dma_mask;
 122
 123     if (addr != res) {
 124         printf("EDU: clamping DMA %#.16"PRIx64" to %#.16"PRIx64"!\n", addr, res);
 125     }
 126
 127     return res;
 128 }
 129
 130 static void edu_dma_timer(void *opaque)
 131 {
 132     EduState *edu = opaque;
 133     bool raise_irq = false;
 134
 135     if (!(edu->dma.cmd & EDU_DMA_RUN)) {
 136         return;
 137     }
 138
 139     if (EDU_DMA_DIR(edu->dma.cmd) == EDU_DMA_FROM_PCI) {
 140         uint32_t dst = edu->dma.dst;
 141         edu_check_range(dst, edu->dma.cnt, DMA_START, DMA_SIZE);
 142         dst -= DMA_START;
 143         pci_dma_read(&edu->pdev, edu_clamp_addr(edu, edu->dma.src),
 144                 edu->dma_buf + dst, edu->dma.cnt);
 145     } else {
 146         uint32_t src = edu->dma.src;
 147         edu_check_range(src, edu->dma.cnt, DMA_START, DMA_SIZE);
 148         src -= DMA_START;
 149         pci_dma_write(&edu->pdev, edu_clamp_addr(edu, edu->dma.dst),
 150                 edu->dma_buf + src, edu->dma.cnt);
 151     }
 152
 153     edu->dma.cmd &= ~EDU_DMA_RUN;
 154     if (edu->dma.cmd & EDU_DMA_IRQ) {
 155         raise_irq = true;
 156     }
 157
 158     if (raise_irq) {
 159         edu_raise_irq(edu, DMA_IRQ);
 160     }
 161 }
 162
 163 static void dma_rw(EduState *edu, bool write, dma_addr_t *val, dma_addr_t *dma,
 164                 bool timer)
 165 {
 166     if (write && (edu->dma.cmd & EDU_DMA_RUN)) {
 167         return;
 168     }
 169
 170     if (write) {
 171         *dma = *val;
 172     } else {
 173         *val = *dma;
 174     }
 175
 176     if (timer) {
 177         timer_mod(&edu->dma_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 100);
 178     }
 179 }
 180
 181 static uint64_t edu_mmio_read(void *opaque, hwaddr addr, unsigned size)
 182 {
 183     EduState *edu = opaque;
 184     uint64_t val = ~0ULL;
 185
 186     if (size != 4) {
 187         return val;
 188     }
 189
 190     switch (addr) {
 191     case 0x00:
 192         val = 0x010000edu;
 193         break;
 194     case 0x04:
 195         val = edu->addr4;
 196         break;
 197     case 0x08:
 198         qemu_mutex_lock(&edu->thr_mutex);
 199         val = edu->fact;
 200         qemu_mutex_unlock(&edu->thr_mutex);
 201         break;
 202     case 0x20:
 203         val = atomic_read(&edu->status);
 204         break;
 205     case 0x24:
 206         val = edu->irq_status;
 207         break;
 208     case 0x80:
 209         dma_rw(edu, false, &val, &edu->dma.src, false);
 210         break;
 211     case 0x88:
 212         dma_rw(edu, false, &val, &edu->dma.dst, false);
 213         break;
 214     case 0x90:
 215         dma_rw(edu, false, &val, &edu->dma.cnt, false);
 216         break;
 217     case 0x98:
 218         dma_rw(edu, false, &val, &edu->dma.cmd, false);
 219         break;
 220     }
 221
 222     return val;
 223 }
 224
 225 static void edu_mmio_write(void *opaque, hwaddr addr, uint64_t val,
 226                 unsigned size)
 227 {
 228     EduState *edu = opaque;
 229
 230     if (addr < 0x80 && size != 4) {
 231         return;
 232     }
 233
 234     if (addr >= 0x80 && size != 4 && size != 8) {
 235         return;
 236     }
 237
 238     switch (addr) {
 239     case 0x04:
 240         edu->addr4 = ~val;
 241         break;
 242     case 0x08:
 243         if (atomic_read(&edu->status) & EDU_STATUS_COMPUTING) {
 244             break;
 245         }
 246         /* EDU_STATUS_COMPUTING cannot go 0->1 concurrently, because it is only
 247          * set in this function and it is under the iothread mutex.
 248          */
 249         qemu_mutex_lock(&edu->thr_mutex);
 250         edu->fact = val;
 251         atomic_or(&edu->status, EDU_STATUS_COMPUTING);
 252         qemu_cond_signal(&edu->thr_cond);
 253         qemu_mutex_unlock(&edu->thr_mutex);
 254         break;
 255     case 0x20:
 256         if (val & EDU_STATUS_IRQFACT) {
 257             atomic_or(&edu->status, EDU_STATUS_IRQFACT);
 258         } else {
 259             atomic_and(&edu->status, ~EDU_STATUS_IRQFACT);
 260         }
 261         break;
 262     case 0x60:
 263         edu_raise_irq(edu, val);
 264         break;
 265     case 0x64:
 266         edu_lower_irq(edu, val);
 267         break;
 268     case 0x80:
 269         dma_rw(edu, true, &val, &edu->dma.src, false);
 270         break;
 271     case 0x88:
 272         dma_rw(edu, true, &val, &edu->dma.dst, false);
 273         break;
 274     case 0x90:
 275         dma_rw(edu, true, &val, &edu->dma.cnt, false);
 276         break;
 277     case 0x98:
 278         if (!(val & EDU_DMA_RUN)) {
 279             break;
 280         }
 281         dma_rw(edu, true, &val, &edu->dma.cmd, true);
 282         break;
 283     }
 284 }
 285
 286 static const MemoryRegionOps edu_mmio_ops = {
 287     .read = edu_mmio_read,
 288     .write = edu_mmio_write,
 289     .endianness = DEVICE_NATIVE_ENDIAN,
 290 };
 291
 292 /*
 293  * We purposely use a thread, so that users are forced to wait for the status
 294  * register.
 295  */
 296 static void *edu_fact_thread(void *opaque)
 297 {
 298     EduState *edu = opaque;
 299
 300     while (1) {
 301         uint32_t val, ret = 1;
 302
 303         qemu_mutex_lock(&edu->thr_mutex);
 304         while ((atomic_read(&edu->status) & EDU_STATUS_COMPUTING) == 0 &&
 305                         !edu->stopping) {
 306             qemu_cond_wait(&edu->thr_cond, &edu->thr_mutex);
 307         }
 308
 309         if (edu->stopping) {
 310             qemu_mutex_unlock(&edu->thr_mutex);
 311             break;
 312         }
 313
 314         val = edu->fact;
 315         qemu_mutex_unlock(&edu->thr_mutex);
 316
 317         while (val > 0) {
 318             ret *= val--;
 319         }
 320
 321         /*
 322          * We should sleep for a random period here, so that students are
 323          * forced to check the status properly.
 324          */
 325
 326         qemu_mutex_lock(&edu->thr_mutex);
 327         edu->fact = ret;
 328         qemu_mutex_unlock(&edu->thr_mutex);
 329         atomic_and(&edu->status, ~EDU_STATUS_COMPUTING);
 330
 331         if (atomic_read(&edu->status) & EDU_STATUS_IRQFACT) {
 332             qemu_mutex_lock_iothread();
 333             edu_raise_irq(edu, FACT_IRQ);
 334             qemu_mutex_unlock_iothread();
 335         }
 336     }
 337
 338     return NULL;
 339 }
 340
 341 static void pci_edu_realize(PCIDevice *pdev, Error **errp)
 342 {
 343     EduState *edu = DO_UPCAST(EduState, pdev, pdev);
 344     uint8_t *pci_conf = pdev->config;
 345
 346     pci_config_set_interrupt_pin(pci_conf, 1);
 347
 348     if (msi_init(pdev, 0, 1, true, false, errp)) {
 349         return;
 350     }
 351
 352     timer_init_ms(&edu->dma_timer, QEMU_CLOCK_VIRTUAL, edu_dma_timer, edu);
 353
 354     qemu_mutex_init(&edu->thr_mutex);
 355     qemu_cond_init(&edu->thr_cond);
 356     qemu_thread_create(&edu->thread, "edu", edu_fact_thread,
 357                        edu, QEMU_THREAD_JOINABLE);
 358
 359     memory_region_init_io(&edu->mmio, OBJECT(edu), &edu_mmio_ops, edu,
 360                     "edu-mmio", 1 << 20);
 361     pci_register_bar(pdev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &edu->mmio);
 362 }
 363
 364 static void pci_edu_uninit(PCIDevice *pdev)
 365 {
 366     EduState *edu = DO_UPCAST(EduState, pdev, pdev);
 367
 368     qemu_mutex_lock(&edu->thr_mutex);
 369     edu->stopping = true;
 370     qemu_mutex_unlock(&edu->thr_mutex);
 371     qemu_cond_signal(&edu->thr_cond);
 372     qemu_thread_join(&edu->thread);
 373
 374     qemu_cond_destroy(&edu->thr_cond);
 375     qemu_mutex_destroy(&edu->thr_mutex);
 376
 377     timer_del(&edu->dma_timer);
 378 }
 379
 380 static void edu_obj_uint64(Object *obj, Visitor *v, const char *name,
 381                            void *opaque, Error **errp)
 382 {
 383     uint64_t *val = opaque;
 384
 385     visit_type_uint64(v, name, val, errp);
 386 }
 387
 388 static void edu_instance_init(Object *obj)
 389 {
 390     EduState *edu = EDU(obj);
 391
 392     edu->dma_mask = (1UL << 28) - 1;
 393     object_property_add(obj, "dma_mask", "uint64", edu_obj_uint64,
 394                     edu_obj_uint64, NULL, &edu->dma_mask, NULL);
 395 }
 396
 397 static void edu_class_init(ObjectClass *class, void *data)
 398 {
 399     PCIDeviceClass *k = PCI_DEVICE_CLASS(class);
 400
 401     k->realize = pci_edu_realize;
 402     k->exit = pci_edu_uninit;
 403     k->vendor_id = PCI_VENDOR_ID_QEMU;
 404     k->device_id = 0x11e8;
 405     k->revision = 0x10;
 406     k->class_id = PCI_CLASS_OTHERS;
 407 }
 408
 409 static void pci_edu_register_types(void)
 410 {
 411     static const TypeInfo edu_info = {
 412         .name          = "edu",
 413         .parent        = TYPE_PCI_DEVICE,
 414         .instance_size = sizeof(EduState),
 415         .instance_init = edu_instance_init,
 416         .class_init    = edu_class_init,
 417     };
 418
 419     type_register_static(&edu_info);
 420 }
 421 type_init(pci_edu_register_types)