linux/drivers/virtio/virtio_mmio.c
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   1/*
   2 * Virtio memory mapped device driver
   3 *
   4 * Copyright 2011, ARM Ltd.
   5 *
   6 * This module allows virtio devices to be used over a virtual, memory mapped
   7 * platform device.
   8 *
   9 * The guest device(s) may be instantiated in one of three equivalent ways:
  10 *
  11 * 1. Static platform device in board's code, eg.:
  12 *
  13 *      static struct platform_device v2m_virtio_device = {
  14 *              .name = "virtio-mmio",
  15 *              .id = -1,
  16 *              .num_resources = 2,
  17 *              .resource = (struct resource []) {
  18 *                      {
  19 *                              .start = 0x1001e000,
  20 *                              .end = 0x1001e0ff,
  21 *                              .flags = IORESOURCE_MEM,
  22 *                      }, {
  23 *                              .start = 42 + 32,
  24 *                              .end = 42 + 32,
  25 *                              .flags = IORESOURCE_IRQ,
  26 *                      },
  27 *              }
  28 *      };
  29 *
  30 * 2. Device Tree node, eg.:
  31 *
  32 *              virtio_block@1e000 {
  33 *                      compatible = "virtio,mmio";
  34 *                      reg = <0x1e000 0x100>;
  35 *                      interrupts = <42>;
  36 *              }
  37 *
  38 * 3. Kernel module (or command line) parameter. Can be used more than once -
  39 *    one device will be created for each one. Syntax:
  40 *
  41 *              [virtio_mmio.]device=<size>@<baseaddr>:<irq>[:<id>]
  42 *    where:
  43 *              <size>     := size (can use standard suffixes like K, M or G)
  44 *              <baseaddr> := physical base address
  45 *              <irq>      := interrupt number (as passed to request_irq())
  46 *              <id>       := (optional) platform device id
  47 *    eg.:
  48 *              virtio_mmio.device=0x100@0x100b0000:48 \
  49 *                              virtio_mmio.device=1K@0x1001e000:74
  50 *
  51 *
  52 *
  53 * Registers layout (all 32-bit wide):
  54 *
  55 * offset d. name             description
  56 * ------ -- ---------------- -----------------
  57 *
  58 * 0x000  R  MagicValue       Magic value "virt"
  59 * 0x004  R  Version          Device version (current max. 1)
  60 * 0x008  R  DeviceID         Virtio device ID
  61 * 0x00c  R  VendorID         Virtio vendor ID
  62 *
  63 * 0x010  R  HostFeatures     Features supported by the host
  64 * 0x014  W  HostFeaturesSel  Set of host features to access via HostFeatures
  65 *
  66 * 0x020  W  GuestFeatures    Features activated by the guest
  67 * 0x024  W  GuestFeaturesSel Set of activated features to set via GuestFeatures
  68 * 0x028  W  GuestPageSize    Size of guest's memory page in bytes
  69 *
  70 * 0x030  W  QueueSel         Queue selector
  71 * 0x034  R  QueueNumMax      Maximum size of the currently selected queue
  72 * 0x038  W  QueueNum         Queue size for the currently selected queue
  73 * 0x03c  W  QueueAlign       Used Ring alignment for the current queue
  74 * 0x040  RW QueuePFN         PFN for the currently selected queue
  75 *
  76 * 0x050  W  QueueNotify      Queue notifier
  77 * 0x060  R  InterruptStatus  Interrupt status register
  78 * 0x060  W  InterruptACK     Interrupt acknowledge register
  79 * 0x070  RW Status           Device status register
  80 *
  81 * 0x100+ RW                  Device-specific configuration space
  82 *
  83 * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
  84 *
  85 * This work is licensed under the terms of the GNU GPL, version 2 or later.
  86 * See the COPYING file in the top-level directory.
  87 */
  88
  89#define pr_fmt(fmt) "virtio-mmio: " fmt
  90
  91#include <linux/highmem.h>
  92#include <linux/interrupt.h>
  93#include <linux/io.h>
  94#include <linux/list.h>
  95#include <linux/module.h>
  96#include <linux/platform_device.h>
  97#include <linux/slab.h>
  98#include <linux/spinlock.h>
  99#include <linux/virtio.h>
 100#include <linux/virtio_config.h>
 101#include <linux/virtio_mmio.h>
 102#include <linux/virtio_ring.h>
 103
 104
 105
 106/* The alignment to use between consumer and producer parts of vring.
 107 * Currently hardcoded to the page size. */
 108#define VIRTIO_MMIO_VRING_ALIGN         PAGE_SIZE
 109
 110
 111
 112#define to_virtio_mmio_device(_plat_dev) \
 113        container_of(_plat_dev, struct virtio_mmio_device, vdev)
 114
 115struct virtio_mmio_device {
 116        struct virtio_device vdev;
 117        struct platform_device *pdev;
 118
 119        void __iomem *base;
 120        unsigned long version;
 121
 122        /* a list of queues so we can dispatch IRQs */
 123        spinlock_t lock;
 124        struct list_head virtqueues;
 125};
 126
 127struct virtio_mmio_vq_info {
 128        /* the actual virtqueue */
 129        struct virtqueue *vq;
 130
 131        /* the number of entries in the queue */
 132        unsigned int num;
 133
 134        /* the virtual address of the ring queue */
 135        void *queue;
 136
 137        /* the list node for the virtqueues list */
 138        struct list_head node;
 139};
 140
 141
 142
 143/* Configuration interface */
 144
 145static u32 vm_get_features(struct virtio_device *vdev)
 146{
 147        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 148
 149        /* TODO: Features > 32 bits */
 150        writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
 151
 152        return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
 153}
 154
 155static void vm_finalize_features(struct virtio_device *vdev)
 156{
 157        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 158        int i;
 159
 160        /* Give virtio_ring a chance to accept features. */
 161        vring_transport_features(vdev);
 162
 163        for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
 164                writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
 165                writel(vdev->features[i],
 166                                vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
 167        }
 168}
 169
 170static void vm_get(struct virtio_device *vdev, unsigned offset,
 171                   void *buf, unsigned len)
 172{
 173        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 174        u8 *ptr = buf;
 175        int i;
 176
 177        for (i = 0; i < len; i++)
 178                ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 179}
 180
 181static void vm_set(struct virtio_device *vdev, unsigned offset,
 182                   const void *buf, unsigned len)
 183{
 184        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 185        const u8 *ptr = buf;
 186        int i;
 187
 188        for (i = 0; i < len; i++)
 189                writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 190}
 191
 192static u8 vm_get_status(struct virtio_device *vdev)
 193{
 194        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 195
 196        return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
 197}
 198
 199static void vm_set_status(struct virtio_device *vdev, u8 status)
 200{
 201        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 202
 203        /* We should never be setting status to 0. */
 204        BUG_ON(status == 0);
 205
 206        writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
 207}
 208
 209static void vm_reset(struct virtio_device *vdev)
 210{
 211        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 212
 213        /* 0 status means a reset. */
 214        writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
 215}
 216
 217
 218
 219/* Transport interface */
 220
 221/* the notify function used when creating a virt queue */
 222static void vm_notify(struct virtqueue *vq)
 223{
 224        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 225
 226        /* We write the queue's selector into the notification register to
 227         * signal the other end */
 228        writel(virtqueue_get_queue_index(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
 229}
 230
 231/* Notify all virtqueues on an interrupt. */
 232static irqreturn_t vm_interrupt(int irq, void *opaque)
 233{
 234        struct virtio_mmio_device *vm_dev = opaque;
 235        struct virtio_mmio_vq_info *info;
 236        struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver,
 237                        struct virtio_driver, driver);
 238        unsigned long status;
 239        unsigned long flags;
 240        irqreturn_t ret = IRQ_NONE;
 241
 242        /* Read and acknowledge interrupts */
 243        status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
 244        writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
 245
 246        if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)
 247                        && vdrv && vdrv->config_changed) {
 248                vdrv->config_changed(&vm_dev->vdev);
 249                ret = IRQ_HANDLED;
 250        }
 251
 252        if (likely(status & VIRTIO_MMIO_INT_VRING)) {
 253                spin_lock_irqsave(&vm_dev->lock, flags);
 254                list_for_each_entry(info, &vm_dev->virtqueues, node)
 255                        ret |= vring_interrupt(irq, info->vq);
 256                spin_unlock_irqrestore(&vm_dev->lock, flags);
 257        }
 258
 259        return ret;
 260}
 261
 262
 263
 264static void vm_del_vq(struct virtqueue *vq)
 265{
 266        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 267        struct virtio_mmio_vq_info *info = vq->priv;
 268        unsigned long flags, size;
 269        unsigned int index = virtqueue_get_queue_index(vq);
 270
 271        spin_lock_irqsave(&vm_dev->lock, flags);
 272        list_del(&info->node);
 273        spin_unlock_irqrestore(&vm_dev->lock, flags);
 274
 275        vring_del_virtqueue(vq);
 276
 277        /* Select and deactivate the queue */
 278        writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 279        writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 280
 281        size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
 282        free_pages_exact(info->queue, size);
 283        kfree(info);
 284}
 285
 286static void vm_del_vqs(struct virtio_device *vdev)
 287{
 288        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 289        struct virtqueue *vq, *n;
 290
 291        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 292                vm_del_vq(vq);
 293
 294        free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
 295}
 296
 297
 298
 299static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
 300                                  void (*callback)(struct virtqueue *vq),
 301                                  const char *name)
 302{
 303        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 304        struct virtio_mmio_vq_info *info;
 305        struct virtqueue *vq;
 306        unsigned long flags, size;
 307        int err;
 308
 309        if (!name)
 310                return NULL;
 311
 312        /* Select the queue we're interested in */
 313        writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 314
 315        /* Queue shouldn't already be set up. */
 316        if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
 317                err = -ENOENT;
 318                goto error_available;
 319        }
 320
 321        /* Allocate and fill out our active queue description */
 322        info = kmalloc(sizeof(*info), GFP_KERNEL);
 323        if (!info) {
 324                err = -ENOMEM;
 325                goto error_kmalloc;
 326        }
 327
 328        /* Allocate pages for the queue - start with a queue as big as
 329         * possible (limited by maximum size allowed by device), drop down
 330         * to a minimal size, just big enough to fit descriptor table
 331         * and two rings (which makes it "alignment_size * 2")
 332         */
 333        info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
 334
 335        /* If the device reports a 0 entry queue, we won't be able to
 336         * use it to perform I/O, and vring_new_virtqueue() can't create
 337         * empty queues anyway, so don't bother to set up the device.
 338         */
 339        if (info->num == 0) {
 340                err = -ENOENT;
 341                goto error_alloc_pages;
 342        }
 343
 344        while (1) {
 345                size = PAGE_ALIGN(vring_size(info->num,
 346                                VIRTIO_MMIO_VRING_ALIGN));
 347                /* Did the last iter shrink the queue below minimum size? */
 348                if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
 349                        err = -ENOMEM;
 350                        goto error_alloc_pages;
 351                }
 352
 353                info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
 354                if (info->queue)
 355                        break;
 356
 357                info->num /= 2;
 358        }
 359
 360        /* Activate the queue */
 361        writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
 362        writel(VIRTIO_MMIO_VRING_ALIGN,
 363                        vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
 364        writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
 365                        vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 366
 367        /* Create the vring */
 368        vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
 369                                 true, info->queue, vm_notify, callback, name);
 370        if (!vq) {
 371                err = -ENOMEM;
 372                goto error_new_virtqueue;
 373        }
 374
 375        vq->priv = info;
 376        info->vq = vq;
 377
 378        spin_lock_irqsave(&vm_dev->lock, flags);
 379        list_add(&info->node, &vm_dev->virtqueues);
 380        spin_unlock_irqrestore(&vm_dev->lock, flags);
 381
 382        return vq;
 383
 384error_new_virtqueue:
 385        writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 386        free_pages_exact(info->queue, size);
 387error_alloc_pages:
 388        kfree(info);
 389error_kmalloc:
 390error_available:
 391        return ERR_PTR(err);
 392}
 393
 394static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 395                       struct virtqueue *vqs[],
 396                       vq_callback_t *callbacks[],
 397                       const char *names[])
 398{
 399        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 400        unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
 401        int i, err;
 402
 403        err = request_irq(irq, vm_interrupt, IRQF_SHARED,
 404                        dev_name(&vdev->dev), vm_dev);
 405        if (err)
 406                return err;
 407
 408        for (i = 0; i < nvqs; ++i) {
 409                vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
 410                if (IS_ERR(vqs[i])) {
 411                        vm_del_vqs(vdev);
 412                        return PTR_ERR(vqs[i]);
 413                }
 414        }
 415
 416        return 0;
 417}
 418
 419static const char *vm_bus_name(struct virtio_device *vdev)
 420{
 421        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 422
 423        return vm_dev->pdev->name;
 424}
 425
 426static struct virtio_config_ops virtio_mmio_config_ops = {
 427        .get            = vm_get,
 428        .set            = vm_set,
 429        .get_status     = vm_get_status,
 430        .set_status     = vm_set_status,
 431        .reset          = vm_reset,
 432        .find_vqs       = vm_find_vqs,
 433        .del_vqs        = vm_del_vqs,
 434        .get_features   = vm_get_features,
 435        .finalize_features = vm_finalize_features,
 436        .bus_name       = vm_bus_name,
 437};
 438
 439
 440
 441/* Platform device */
 442
 443static int __devinit virtio_mmio_probe(struct platform_device *pdev)
 444{
 445        struct virtio_mmio_device *vm_dev;
 446        struct resource *mem;
 447        unsigned long magic;
 448
 449        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 450        if (!mem)
 451                return -EINVAL;
 452
 453        if (!devm_request_mem_region(&pdev->dev, mem->start,
 454                        resource_size(mem), pdev->name))
 455                return -EBUSY;
 456
 457        vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
 458        if (!vm_dev)
 459                return  -ENOMEM;
 460
 461        vm_dev->vdev.dev.parent = &pdev->dev;
 462        vm_dev->vdev.config = &virtio_mmio_config_ops;
 463        vm_dev->pdev = pdev;
 464        INIT_LIST_HEAD(&vm_dev->virtqueues);
 465        spin_lock_init(&vm_dev->lock);
 466
 467        vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
 468        if (vm_dev->base == NULL)
 469                return -EFAULT;
 470
 471        /* Check magic value */
 472        magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 473        if (memcmp(&magic, "virt", 4) != 0) {
 474                dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
 475                return -ENODEV;
 476        }
 477
 478        /* Check device version */
 479        vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
 480        if (vm_dev->version != 1) {
 481                dev_err(&pdev->dev, "Version %ld not supported!\n",
 482                                vm_dev->version);
 483                return -ENXIO;
 484        }
 485
 486        vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
 487        vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 488
 489        writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 490
 491        platform_set_drvdata(pdev, vm_dev);
 492
 493        return register_virtio_device(&vm_dev->vdev);
 494}
 495
 496static int __devexit virtio_mmio_remove(struct platform_device *pdev)
 497{
 498        struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
 499
 500        unregister_virtio_device(&vm_dev->vdev);
 501
 502        return 0;
 503}
 504
 505
 506
 507/* Devices list parameter */
 508
 509#if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
 510
 511static struct device vm_cmdline_parent = {
 512        .init_name = "virtio-mmio-cmdline",
 513};
 514
 515static int vm_cmdline_parent_registered;
 516static int vm_cmdline_id;
 517
 518static int vm_cmdline_set(const char *device,
 519                const struct kernel_param *kp)
 520{
 521        int err;
 522        struct resource resources[2] = {};
 523        char *str;
 524        long long int base;
 525        int processed, consumed = 0;
 526        struct platform_device *pdev;
 527
 528        resources[0].flags = IORESOURCE_MEM;
 529        resources[1].flags = IORESOURCE_IRQ;
 530
 531        resources[0].end = memparse(device, &str) - 1;
 532
 533        processed = sscanf(str, "@%lli:%u%n:%d%n",
 534                        &base, &resources[1].start, &consumed,
 535                        &vm_cmdline_id, &consumed);
 536
 537        if (processed < 2 || processed > 3 || str[consumed])
 538                return -EINVAL;
 539
 540        resources[0].start = base;
 541        resources[0].end += base;
 542        resources[1].end = resources[1].start;
 543
 544        if (!vm_cmdline_parent_registered) {
 545                err = device_register(&vm_cmdline_parent);
 546                if (err) {
 547                        pr_err("Failed to register parent device!\n");
 548                        return err;
 549                }
 550                vm_cmdline_parent_registered = 1;
 551        }
 552
 553        pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
 554                       vm_cmdline_id,
 555                       (unsigned long long)resources[0].start,
 556                       (unsigned long long)resources[0].end,
 557                       (int)resources[1].start);
 558
 559        pdev = platform_device_register_resndata(&vm_cmdline_parent,
 560                        "virtio-mmio", vm_cmdline_id++,
 561                        resources, ARRAY_SIZE(resources), NULL, 0);
 562        if (IS_ERR(pdev))
 563                return PTR_ERR(pdev);
 564
 565        return 0;
 566}
 567
 568static int vm_cmdline_get_device(struct device *dev, void *data)
 569{
 570        char *buffer = data;
 571        unsigned int len = strlen(buffer);
 572        struct platform_device *pdev = to_platform_device(dev);
 573
 574        snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
 575                        pdev->resource[0].end - pdev->resource[0].start + 1ULL,
 576                        (unsigned long long)pdev->resource[0].start,
 577                        (unsigned long long)pdev->resource[1].start,
 578                        pdev->id);
 579        return 0;
 580}
 581
 582static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
 583{
 584        buffer[0] = '\0';
 585        device_for_each_child(&vm_cmdline_parent, buffer,
 586                        vm_cmdline_get_device);
 587        return strlen(buffer) + 1;
 588}
 589
 590static struct kernel_param_ops vm_cmdline_param_ops = {
 591        .set = vm_cmdline_set,
 592        .get = vm_cmdline_get,
 593};
 594
 595device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
 596
 597static int vm_unregister_cmdline_device(struct device *dev,
 598                void *data)
 599{
 600        platform_device_unregister(to_platform_device(dev));
 601
 602        return 0;
 603}
 604
 605static void vm_unregister_cmdline_devices(void)
 606{
 607        if (vm_cmdline_parent_registered) {
 608                device_for_each_child(&vm_cmdline_parent, NULL,
 609                                vm_unregister_cmdline_device);
 610                device_unregister(&vm_cmdline_parent);
 611                vm_cmdline_parent_registered = 0;
 612        }
 613}
 614
 615#else
 616
 617static void vm_unregister_cmdline_devices(void)
 618{
 619}
 620
 621#endif
 622
 623/* Platform driver */
 624
 625static struct of_device_id virtio_mmio_match[] = {
 626        { .compatible = "virtio,mmio", },
 627        {},
 628};
 629MODULE_DEVICE_TABLE(of, virtio_mmio_match);
 630
 631static struct platform_driver virtio_mmio_driver = {
 632        .probe          = virtio_mmio_probe,
 633        .remove         = __devexit_p(virtio_mmio_remove),
 634        .driver         = {
 635                .name   = "virtio-mmio",
 636                .owner  = THIS_MODULE,
 637                .of_match_table = virtio_mmio_match,
 638        },
 639};
 640
 641static int __init virtio_mmio_init(void)
 642{
 643        return platform_driver_register(&virtio_mmio_driver);
 644}
 645
 646static void __exit virtio_mmio_exit(void)
 647{
 648        platform_driver_unregister(&virtio_mmio_driver);
 649        vm_unregister_cmdline_devices();
 650}
 651
 652module_init(virtio_mmio_init);
 653module_exit(virtio_mmio_exit);
 654
 655MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
 656MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
 657MODULE_LICENSE("GPL");
 658
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