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 "qemu/units.h"
  27 #include "hw/pci/pci.h"
  28 #include "hw/pci/msi.h"
  29 #include "qemu/timer.h"
  30 #include "qemu/main-loop.h" /* iothread mutex */
  31 #include "qapi/visitor.h"
  32
  33 #define TYPE_PCI_EDU_DEVICE "edu"
  34 #define EDU(obj)        OBJECT_CHECK(EduState, obj, TYPE_PCI_EDU_DEVICE)
  35
  36 #define FACT_IRQ        0x00000001
  37 #define DMA_IRQ         0x00000100
  38
  39 #define DMA_START       0x40000
  40 #define DMA_SIZE        4096
  41
  42 typedef struct {
  43     PCIDevice pdev;
  44     MemoryRegion mmio;
  45
  46     QemuThread thread;
  47     QemuMutex thr_mutex;
  48     QemuCond thr_cond;
  49     bool stopping;
  50
  51     uint32_t addr4;
  52     uint32_t fact;
  53 #define EDU_STATUS_COMPUTING    0x01
  54 #define EDU_STATUS_IRQFACT      0x80
  55     uint32_t status;
  56
  57     uint32_t irq_status;
  58
  59 #define EDU_DMA_RUN             0x1
  60 #define EDU_DMA_DIR(cmd)        (((cmd) & 0x2) >> 1)
  61 # define EDU_DMA_FROM_PCI       0
  62 # define EDU_DMA_TO_PCI         1
  63 #define EDU_DMA_IRQ             0x4
  64     struct dma_state {
  65         dma_addr_t src;
  66         dma_addr_t dst;
  67         dma_addr_t cnt;
  68         dma_addr_t cmd;
  69     } dma;
  70     QEMUTimer dma_timer;
  71     char dma_buf[DMA_SIZE];
  72     uint64_t dma_mask;
  73 } EduState;
  74
  75 static bool edu_msi_enabled(EduState *edu)
  76 {
  77     return msi_enabled(&edu->pdev);
  78 }
  79
  80 static void edu_raise_irq(EduState *edu, uint32_t val)
  81 {
  82     edu->irq_status |= val;
  83     if (edu->irq_status) {
  84         if (edu_msi_enabled(edu)) {
  85             msi_notify(&edu->pdev, 0);
  86         } else {
  87             pci_set_irq(&edu->pdev, 1);
  88         }
  89     }
  90 }
  91
  92 static void edu_lower_irq(EduState *edu, uint32_t val)
  93 {
  94     edu->irq_status &= ~val;
  95
  96     if (!edu->irq_status && !edu_msi_enabled(edu)) {
  97         pci_set_irq(&edu->pdev, 0);
  98     }
  99 }
 100
 101 static bool within(uint32_t addr, uint32_t start, uint32_t end)
 102 {
 103     return start <= addr && addr < end;
 104 }
 105
 106 static void edu_check_range(uint32_t addr, uint32_t size1, uint32_t start,
 107                 uint32_t size2)
 108 {
 109     uint32_t end1 = addr + size1;
 110     uint32_t end2 = start + size2;
 111
 112     if (within(addr, start, end2) &&
 113             end1 > addr && within(end1, start, end2)) {
 114         return;
 115     }
 116
 117     hw_error("EDU: DMA range 0x%.8x-0x%.8x out of bounds (0x%.8x-0x%.8x)!",
 118             addr, end1 - 1, start, end2 - 1);
 119 }
 120
 121 static dma_addr_t edu_clamp_addr(const EduState *edu, dma_addr_t addr)
 122 {
 123     dma_addr_t res = addr & edu->dma_mask;
 124
 125     if (addr != res) {
 126         printf("EDU: clamping DMA %#.16"PRIx64" to %#.16"PRIx64"!\n", addr, res);
 127     }
 128
 129     return res;
 130 }
 131
 132 static void edu_dma_timer(void *opaque)
 133 {
 134     EduState *edu = opaque;
 135     bool raise_irq = false;
 136
 137     if (!(edu->dma.cmd & EDU_DMA_RUN)) {
 138         return;
 139     }
 140
 141     if (EDU_DMA_DIR(edu->dma.cmd) == EDU_DMA_FROM_PCI) {
 142         uint32_t dst = edu->dma.dst;
 143         edu_check_range(dst, edu->dma.cnt, DMA_START, DMA_SIZE);
 144         dst -= DMA_START;
 145         pci_dma_read(&edu->pdev, edu_clamp_addr(edu, edu->dma.src),
 146                 edu->dma_buf + dst, edu->dma.cnt);
 147     } else {
 148         uint32_t src = edu->dma.src;
 149         edu_check_range(src, edu->dma.cnt, DMA_START, DMA_SIZE);
 150         src -= DMA_START;
 151         pci_dma_write(&edu->pdev, edu_clamp_addr(edu, edu->dma.dst),
 152                 edu->dma_buf + src, edu->dma.cnt);
 153     }
 154
 155     edu->dma.cmd &= ~EDU_DMA_RUN;
 156     if (edu->dma.cmd & EDU_DMA_IRQ) {
 157         raise_irq = true;
 158     }
 159
 160     if (raise_irq) {
 161         edu_raise_irq(edu, DMA_IRQ);
 162     }
 163 }
 164
 165 static void dma_rw(EduState *edu, bool write, dma_addr_t *val, dma_addr_t *dma,
 166                 bool timer)
 167 {
 168     if (write && (edu->dma.cmd & EDU_DMA_RUN)) {
 169         return;
 170     }
 171
 172     if (write) {
 173         *dma = *val;
 174     } else {
 175         *val = *dma;
 176     }
 177
 178     if (timer) {
 179         timer_mod(&edu->dma_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + 100);
 180     }
 181 }
 182
 183 static uint64_t edu_mmio_read(void *opaque, hwaddr addr, unsigned size)
 184 {
 185     EduState *edu = opaque;
 186     uint64_t val = ~0ULL;
 187
 188     if (size != 4) {
 189         return val;
 190     }
 191
 192     switch (addr) {
 193     case 0x00:
 194         val = 0x010000edu;
 195         break;
 196     case 0x04:
 197         val = edu->addr4;
 198         break;
 199     case 0x08:
 200         qemu_mutex_lock(&edu->thr_mutex);
 201         val = edu->fact;
 202         qemu_mutex_unlock(&edu->thr_mutex);
 203         break;
 204     case 0x20:
 205         val = atomic_read(&edu->status);
 206         break;
 207     case 0x24:
 208         val = edu->irq_status;
 209         break;
 210     case 0x80:
 211         dma_rw(edu, false, &val, &edu->dma.src, false);
 212         break;
 213     case 0x88:
 214         dma_rw(edu, false, &val, &edu->dma.dst, false);
 215         break;
 216     case 0x90:
 217         dma_rw(edu, false, &val, &edu->dma.cnt, false);
 218         break;
 219     case 0x98:
 220         dma_rw(edu, false, &val, &edu->dma.cmd, false);
 221         break;
 222     }
 223
 224     return val;
 225 }
 226
 227 static void edu_mmio_write(void *opaque, hwaddr addr, uint64_t val,
 228                 unsigned size)
 229 {
 230     EduState *edu = opaque;
 231
 232     if (addr < 0x80 && size != 4) {
 233         return;
 234     }
 235
 236     if (addr >= 0x80 && size != 4 && size != 8) {
 237         return;
 238     }
 239
 240     switch (addr) {
 241     case 0x04:
 242         edu->addr4 = ~val;
 243         break;
 244     case 0x08:
 245         if (atomic_read(&edu->status) & EDU_STATUS_COMPUTING) {
 246             break;
 247         }
 248         /* EDU_STATUS_COMPUTING cannot go 0->1 concurrently, because it is only
 249          * set in this function and it is under the iothread mutex.
 250          */
 251         qemu_mutex_lock(&edu->thr_mutex);
 252         edu->fact = val;
 253         atomic_or(&edu->status, EDU_STATUS_COMPUTING);
 254         qemu_cond_signal(&edu->thr_cond);
 255         qemu_mutex_unlock(&edu->thr_mutex);
 256         break;
 257     case 0x20:
 258         if (val & EDU_STATUS_IRQFACT) {
 259             atomic_or(&edu->status, EDU_STATUS_IRQFACT);
 260         } else {
 261             atomic_and(&edu->status, ~EDU_STATUS_IRQFACT);
 262         }
 263         break;
 264     case 0x60:
 265         edu_raise_irq(edu, val);
 266         break;
 267     case 0x64:
 268         edu_lower_irq(edu, val);
 269         break;
 270     case 0x80:
 271         dma_rw(edu, true, &val, &edu->dma.src, false);
 272         break;
 273     case 0x88:
 274         dma_rw(edu, true, &val, &edu->dma.dst, false);
 275         break;
 276     case 0x90:
 277         dma_rw(edu, true, &val, &edu->dma.cnt, false);
 278         break;
 279     case 0x98:
 280         if (!(val & EDU_DMA_RUN)) {
 281             break;
 282         }
 283         dma_rw(edu, true, &val, &edu->dma.cmd, true);
 284         break;
 285     }
 286 }
 287
 288 static const MemoryRegionOps edu_mmio_ops = {
 289     .read = edu_mmio_read,
 290     .write = edu_mmio_write,
 291     .endianness = DEVICE_NATIVE_ENDIAN,
 292 };
 293
 294 /*
 295  * We purposely use a thread, so that users are forced to wait for the status
 296  * register.
 297  */
 298 static void *edu_fact_thread(void *opaque)
 299 {
 300     EduState *edu = opaque;
 301
 302     while (1) {
 303         uint32_t val, ret = 1;
 304
 305         qemu_mutex_lock(&edu->thr_mutex);
 306         while ((atomic_read(&edu->status) & EDU_STATUS_COMPUTING) == 0 &&
 307                         !edu->stopping) {
 308             qemu_cond_wait(&edu->thr_cond, &edu->thr_mutex);
 309         }
 310
 311         if (edu->stopping) {
 312             qemu_mutex_unlock(&edu->thr_mutex);
 313             break;
 314         }
 315
 316         val = edu->fact;
 317         qemu_mutex_unlock(&edu->thr_mutex);
 318
 319         while (val > 0) {
 320             ret *= val--;
 321         }
 322
 323         /*
 324          * We should sleep for a random period here, so that students are
 325          * forced to check the status properly.
 326          */
 327
 328         qemu_mutex_lock(&edu->thr_mutex);
 329         edu->fact = ret;
 330         qemu_mutex_unlock(&edu->thr_mutex);
 331         atomic_and(&edu->status, ~EDU_STATUS_COMPUTING);
 332
 333         if (atomic_read(&edu->status) & EDU_STATUS_IRQFACT) {
 334             qemu_mutex_lock_iothread();
 335             edu_raise_irq(edu, FACT_IRQ);
 336             qemu_mutex_unlock_iothread();
 337         }
 338     }
 339
 340     return NULL;
 341 }
 342
 343 static void pci_edu_realize(PCIDevice *pdev, Error **errp)
 344 {
 345     EduState *edu = EDU(pdev);
 346     uint8_t *pci_conf = pdev->config;
 347
 348     pci_config_set_interrupt_pin(pci_conf, 1);
 349
 350     if (msi_init(pdev, 0, 1, true, false, errp)) {
 351         return;
 352     }
 353
 354     timer_init_ms(&edu->dma_timer, QEMU_CLOCK_VIRTUAL, edu_dma_timer, edu);
 355
 356     qemu_mutex_init(&edu->thr_mutex);
 357     qemu_cond_init(&edu->thr_cond);
 358     qemu_thread_create(&edu->thread, "edu", edu_fact_thread,
 359                        edu, QEMU_THREAD_JOINABLE);
 360
 361     memory_region_init_io(&edu->mmio, OBJECT(edu), &edu_mmio_ops, edu,
 362                     "edu-mmio", 1 * MiB);
 363     pci_register_bar(pdev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &edu->mmio);
 364 }
 365
 366 static void pci_edu_uninit(PCIDevice *pdev)
 367 {
 368     EduState *edu = EDU(pdev);
 369
 370     qemu_mutex_lock(&edu->thr_mutex);
 371     edu->stopping = true;
 372     qemu_mutex_unlock(&edu->thr_mutex);
 373     qemu_cond_signal(&edu->thr_cond);
 374     qemu_thread_join(&edu->thread);
 375
 376     qemu_cond_destroy(&edu->thr_cond);
 377     qemu_mutex_destroy(&edu->thr_mutex);
 378
 379     timer_del(&edu->dma_timer);
 380 }
 381
 382 static void edu_obj_uint64(Object *obj, Visitor *v, const char *name,
 383                            void *opaque, Error **errp)
 384 {
 385     uint64_t *val = opaque;
 386
 387     visit_type_uint64(v, name, val, errp);
 388 }
 389
 390 static void edu_instance_init(Object *obj)
 391 {
 392     EduState *edu = EDU(obj);
 393
 394     edu->dma_mask = (1UL << 28) - 1;
 395     object_property_add(obj, "dma_mask", "uint64", edu_obj_uint64,
 396                     edu_obj_uint64, NULL, &edu->dma_mask, NULL);
 397 }
 398
 399 static void edu_class_init(ObjectClass *class, void *data)
 400 {
 401     PCIDeviceClass *k = PCI_DEVICE_CLASS(class);
 402
 403     k->realize = pci_edu_realize;
 404     k->exit = pci_edu_uninit;
 405     k->vendor_id = PCI_VENDOR_ID_QEMU;
 406     k->device_id = 0x11e8;
 407     k->revision = 0x10;
 408     k->class_id = PCI_CLASS_OTHERS;
 409 }
 410
 411 static void pci_edu_register_types(void)
 412 {
 413     static InterfaceInfo interfaces[] = {
 414         { INTERFACE_CONVENTIONAL_PCI_DEVICE },
 415         { },
 416     };
 417     static const TypeInfo edu_info = {
 418         .name          = TYPE_PCI_EDU_DEVICE,
 419         .parent        = TYPE_PCI_DEVICE,
 420         .instance_size = sizeof(EduState),
 421         .instance_init = edu_instance_init,
 422         .class_init    = edu_class_init,
 423         .interfaces = interfaces,
 424     };
 425
 426     type_register_static(&edu_info);
 427 }
 428 type_init(pci_edu_register_types)