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