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 "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"
  37 typedef struct EduState EduState;
  38 DECLARE_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
  47 struct 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
  80 static bool edu_msi_enabled(EduState *edu)
  81 {
  82     return msi_enabled(&edu->pdev);
  83 }
  84
  85 static 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
  97 static 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
 106 static bool within(uint64_t addr, uint64_t start, uint64_t end)
 107 {
 108     return start <= addr && addr < end;
 109 }
 110
 111 static 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
 127 static 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
 138 static 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
 171 static 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
 189 static 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
 237 static 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             /* Order check of the COMPUTING flag after setting IRQFACT.  */
 271             smp_mb__after_rmw();
 272         } else {
 273             qatomic_and(&edu->status, ~EDU_STATUS_IRQFACT);
 274         }
 275         break;
 276     case 0x60:
 277         edu_raise_irq(edu, val);
 278         break;
 279     case 0x64:
 280         edu_lower_irq(edu, val);
 281         break;
 282     case 0x80:
 283         dma_rw(edu, true, &val, &edu->dma.src, false);
 284         break;
 285     case 0x88:
 286         dma_rw(edu, true, &val, &edu->dma.dst, false);
 287         break;
 288     case 0x90:
 289         dma_rw(edu, true, &val, &edu->dma.cnt, false);
 290         break;
 291     case 0x98:
 292         if (!(val & EDU_DMA_RUN)) {
 293             break;
 294         }
 295         dma_rw(edu, true, &val, &edu->dma.cmd, true);
 296         break;
 297     }
 298 }
 299
 300 static const MemoryRegionOps edu_mmio_ops = {
 301     .read = edu_mmio_read,
 302     .write = edu_mmio_write,
 303     .endianness = DEVICE_NATIVE_ENDIAN,
 304     .valid = {
 305         .min_access_size = 4,
 306         .max_access_size = 8,
 307     },
 308     .impl = {
 309         .min_access_size = 4,
 310         .max_access_size = 8,
 311     },
 312
 313 };
 314
 315 /*
 316  * We purposely use a thread, so that users are forced to wait for the status
 317  * register.
 318  */
 319 static void *edu_fact_thread(void *opaque)
 320 {
 321     EduState *edu = opaque;
 322
 323     while (1) {
 324         uint32_t val, ret = 1;
 325
 326         qemu_mutex_lock(&edu->thr_mutex);
 327         while ((qatomic_read(&edu->status) & EDU_STATUS_COMPUTING) == 0 &&
 328                         !edu->stopping) {
 329             qemu_cond_wait(&edu->thr_cond, &edu->thr_mutex);
 330         }
 331
 332         if (edu->stopping) {
 333             qemu_mutex_unlock(&edu->thr_mutex);
 334             break;
 335         }
 336
 337         val = edu->fact;
 338         qemu_mutex_unlock(&edu->thr_mutex);
 339
 340         while (val > 0) {
 341             ret *= val--;
 342         }
 343
 344         /*
 345          * We should sleep for a random period here, so that students are
 346          * forced to check the status properly.
 347          */
 348
 349         qemu_mutex_lock(&edu->thr_mutex);
 350         edu->fact = ret;
 351         qemu_mutex_unlock(&edu->thr_mutex);
 352         qatomic_and(&edu->status, ~EDU_STATUS_COMPUTING);
 353
 354         /* Clear COMPUTING flag before checking IRQFACT.  */
 355         smp_mb__after_rmw();
 356
 357         if (qatomic_read(&edu->status) & EDU_STATUS_IRQFACT) {
 358             qemu_mutex_lock_iothread();
 359             edu_raise_irq(edu, FACT_IRQ);
 360             qemu_mutex_unlock_iothread();
 361         }
 362     }
 363
 364     return NULL;
 365 }
 366
 367 static void pci_edu_realize(PCIDevice *pdev, Error **errp)
 368 {
 369     EduState *edu = EDU(pdev);
 370     uint8_t *pci_conf = pdev->config;
 371
 372     pci_config_set_interrupt_pin(pci_conf, 1);
 373
 374     if (msi_init(pdev, 0, 1, true, false, errp)) {
 375         return;
 376     }
 377
 378     timer_init_ms(&edu->dma_timer, QEMU_CLOCK_VIRTUAL, edu_dma_timer, edu);
 379
 380     qemu_mutex_init(&edu->thr_mutex);
 381     qemu_cond_init(&edu->thr_cond);
 382     qemu_thread_create(&edu->thread, "edu", edu_fact_thread,
 383                        edu, QEMU_THREAD_JOINABLE);
 384
 385     memory_region_init_io(&edu->mmio, OBJECT(edu), &edu_mmio_ops, edu,
 386                     "edu-mmio", 1 * MiB);
 387     pci_register_bar(pdev, 0, PCI_BASE_ADDRESS_SPACE_MEMORY, &edu->mmio);
 388 }
 389
 390 static void pci_edu_uninit(PCIDevice *pdev)
 391 {
 392     EduState *edu = EDU(pdev);
 393
 394     qemu_mutex_lock(&edu->thr_mutex);
 395     edu->stopping = true;
 396     qemu_mutex_unlock(&edu->thr_mutex);
 397     qemu_cond_signal(&edu->thr_cond);
 398     qemu_thread_join(&edu->thread);
 399
 400     qemu_cond_destroy(&edu->thr_cond);
 401     qemu_mutex_destroy(&edu->thr_mutex);
 402
 403     timer_del(&edu->dma_timer);
 404     msi_uninit(pdev);
 405 }
 406
 407 static void edu_instance_init(Object *obj)
 408 {
 409     EduState *edu = EDU(obj);
 410
 411     edu->dma_mask = (1UL << 28) - 1;
 412     object_property_add_uint64_ptr(obj, "dma_mask",
 413                                    &edu->dma_mask, OBJ_PROP_FLAG_READWRITE);
 414 }
 415
 416 static void edu_class_init(ObjectClass *class, void *data)
 417 {
 418     DeviceClass *dc = DEVICE_CLASS(class);
 419     PCIDeviceClass *k = PCI_DEVICE_CLASS(class);
 420
 421     k->realize = pci_edu_realize;
 422     k->exit = pci_edu_uninit;
 423     k->vendor_id = PCI_VENDOR_ID_QEMU;
 424     k->device_id = 0x11e8;
 425     k->revision = 0x10;
 426     k->class_id = PCI_CLASS_OTHERS;
 427     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
 428 }
 429
 430 static void pci_edu_register_types(void)
 431 {
 432     static InterfaceInfo interfaces[] = {
 433         { INTERFACE_CONVENTIONAL_PCI_DEVICE },
 434         { },
 435     };
 436     static const TypeInfo edu_info = {
 437         .name          = TYPE_PCI_EDU_DEVICE,
 438         .parent        = TYPE_PCI_DEVICE,
 439         .instance_size = sizeof(EduState),
 440         .instance_init = edu_instance_init,
 441         .class_init    = edu_class_init,
 442         .interfaces = interfaces,
 443     };
 444
 445     type_register_static(&edu_info);
 446 }
 447 type_init(pci_edu_register_types)