drivers/virtio/virtio_mmio.c

   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  * Registers layout (all 32-bit wide):
  10  *
  11  * offset d. name             description
  12  * ------ -- ---------------- -----------------
  13  *
  14  * 0x000  R  MagicValue       Magic value "virt"
  15  * 0x004  R  Version          Device version (current max. 1)
  16  * 0x008  R  DeviceID         Virtio device ID
  17  * 0x00c  R  VendorID         Virtio vendor ID
  18  *
  19  * 0x010  R  HostFeatures     Features supported by the host
  20  * 0x014  W  HostFeaturesSel  Set of host features to access via HostFeatures
  21  *
  22  * 0x020  W  GuestFeatures    Features activated by the guest
  23  * 0x024  W  GuestFeaturesSel Set of activated features to set via GuestFeatures
  24  * 0x028  W  GuestPageSize    Size of guest's memory page in bytes
  25  *
  26  * 0x030  W  QueueSel         Queue selector
  27  * 0x034  R  QueueNumMax      Maximum size of the currently selected queue
  28  * 0x038  W  QueueNum         Queue size for the currently selected queue
  29  * 0x03c  W  QueueAlign       Used Ring alignment for the current queue
  30  * 0x040  RW QueuePFN         PFN for the currently selected queue
  31  *
  32  * 0x050  W  QueueNotify      Queue notifier
  33  * 0x060  R  InterruptStatus  Interrupt status register
  34  * 0x060  W  InterruptACK     Interrupt acknowledge register
  35  * 0x070  RW Status           Device status register
  36  *
  37  * 0x100+ RW                  Device-specific configuration space
  38  *
  39  * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
  40  *
  41  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  42  * See the COPYING file in the top-level directory.
  43  */
  44
  45 #include <linux/highmem.h>
  46 #include <linux/interrupt.h>
  47 #include <linux/io.h>
  48 #include <linux/list.h>
  49 #include <linux/module.h>
  50 #include <linux/platform_device.h>
  51 #include <linux/slab.h>
  52 #include <linux/spinlock.h>
  53 #include <linux/virtio.h>
  54 #include <linux/virtio_config.h>
  55 #include <linux/virtio_mmio.h>
  56 #include <linux/virtio_ring.h>
  57
  58
  59
  60 /* The alignment to use between consumer and producer parts of vring.
  61  * Currently hardcoded to the page size. */
  62 #define VIRTIO_MMIO_VRING_ALIGN         PAGE_SIZE
  63
  64
  65
  66 #define to_virtio_mmio_device(_plat_dev) \
  67         container_of(_plat_dev, struct virtio_mmio_device, vdev)
  68
  69 struct virtio_mmio_device {
  70         struct virtio_device vdev;
  71         struct platform_device *pdev;
  72
  73         void __iomem *base;
  74         unsigned long version;
  75
  76         /* a list of queues so we can dispatch IRQs */
  77         spinlock_t lock;
  78         struct list_head virtqueues;
  79 };
  80
  81 struct virtio_mmio_vq_info {
  82         /* the actual virtqueue */
  83         struct virtqueue *vq;
  84
  85         /* the number of entries in the queue */
  86         unsigned int num;
  87
  88         /* the index of the queue */
  89         int queue_index;
  90
  91         /* the virtual address of the ring queue */
  92         void *queue;
  93
  94         /* the list node for the virtqueues list */
  95         struct list_head node;
  96 };
  97
  98
  99
 100 /* Configuration interface */
 101
 102 static u32 vm_get_features(struct virtio_device *vdev)
 103 {
 104         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 105
 106         /* TODO: Features > 32 bits */
 107         writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
 108
 109         return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
 110 }
 111
 112 static void vm_finalize_features(struct virtio_device *vdev)
 113 {
 114         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 115         int i;
 116
 117         /* Give virtio_ring a chance to accept features. */
 118         vring_transport_features(vdev);
 119
 120         for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
 121                 writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
 122                 writel(vdev->features[i],
 123                                 vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
 124         }
 125 }
 126
 127 static void vm_get(struct virtio_device *vdev, unsigned offset,
 128                    void *buf, unsigned len)
 129 {
 130         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 131         u8 *ptr = buf;
 132         int i;
 133
 134         for (i = 0; i < len; i++)
 135                 ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 136 }
 137
 138 static void vm_set(struct virtio_device *vdev, unsigned offset,
 139                    const void *buf, unsigned len)
 140 {
 141         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 142         const u8 *ptr = buf;
 143         int i;
 144
 145         for (i = 0; i < len; i++)
 146                 writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 147 }
 148
 149 static u8 vm_get_status(struct virtio_device *vdev)
 150 {
 151         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 152
 153         return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
 154 }
 155
 156 static void vm_set_status(struct virtio_device *vdev, u8 status)
 157 {
 158         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 159
 160         /* We should never be setting status to 0. */
 161         BUG_ON(status == 0);
 162
 163         writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
 164 }
 165
 166 static void vm_reset(struct virtio_device *vdev)
 167 {
 168         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 169
 170         /* 0 status means a reset. */
 171         writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
 172 }
 173
 174
 175
 176 /* Transport interface */
 177
 178 /* the notify function used when creating a virt queue */
 179 static void vm_notify(struct virtqueue *vq)
 180 {
 181         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 182         struct virtio_mmio_vq_info *info = vq->priv;
 183
 184         /* We write the queue's selector into the notification register to
 185          * signal the other end */
 186         writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
 187 }
 188
 189 /* Notify all virtqueues on an interrupt. */
 190 static irqreturn_t vm_interrupt(int irq, void *opaque)
 191 {
 192         struct virtio_mmio_device *vm_dev = opaque;
 193         struct virtio_mmio_vq_info *info;
 194         struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver,
 195                         struct virtio_driver, driver);
 196         unsigned long status;
 197         unsigned long flags;
 198         irqreturn_t ret = IRQ_NONE;
 199
 200         /* Read and acknowledge interrupts */
 201         status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
 202         writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
 203
 204         if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)
 205                         && vdrv && vdrv->config_changed) {
 206                 vdrv->config_changed(&vm_dev->vdev);
 207                 ret = IRQ_HANDLED;
 208         }
 209
 210         if (likely(status & VIRTIO_MMIO_INT_VRING)) {
 211                 spin_lock_irqsave(&vm_dev->lock, flags);
 212                 list_for_each_entry(info, &vm_dev->virtqueues, node)
 213                         ret |= vring_interrupt(irq, info->vq);
 214                 spin_unlock_irqrestore(&vm_dev->lock, flags);
 215         }
 216
 217         return ret;
 218 }
 219
 220
 221
 222 static void vm_del_vq(struct virtqueue *vq)
 223 {
 224         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 225         struct virtio_mmio_vq_info *info = vq->priv;
 226         unsigned long flags, size;
 227
 228         spin_lock_irqsave(&vm_dev->lock, flags);
 229         list_del(&info->node);
 230         spin_unlock_irqrestore(&vm_dev->lock, flags);
 231
 232         vring_del_virtqueue(vq);
 233
 234         /* Select and deactivate the queue */
 235         writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 236         writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 237
 238         size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
 239         free_pages_exact(info->queue, size);
 240         kfree(info);
 241 }
 242
 243 static void vm_del_vqs(struct virtio_device *vdev)
 244 {
 245         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 246         struct virtqueue *vq, *n;
 247
 248         list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 249                 vm_del_vq(vq);
 250
 251         free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
 252 }
 253
 254
 255
 256 static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
 257                                   void (*callback)(struct virtqueue *vq),
 258                                   const char *name)
 259 {
 260         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 261         struct virtio_mmio_vq_info *info;
 262         struct virtqueue *vq;
 263         unsigned long flags, size;
 264         int err;
 265
 266         /* Select the queue we're interested in */
 267         writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 268
 269         /* Queue shouldn't already be set up. */
 270         if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
 271                 err = -ENOENT;
 272                 goto error_available;
 273         }
 274
 275         /* Allocate and fill out our active queue description */
 276         info = kmalloc(sizeof(*info), GFP_KERNEL);
 277         if (!info) {
 278                 err = -ENOMEM;
 279                 goto error_kmalloc;
 280         }
 281         info->queue_index = index;
 282
 283         /* Allocate pages for the queue - start with a queue as big as
 284          * possible (limited by maximum size allowed by device), drop down
 285          * to a minimal size, just big enough to fit descriptor table
 286          * and two rings (which makes it "alignment_size * 2")
 287          */
 288         info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
 289         while (1) {
 290                 size = PAGE_ALIGN(vring_size(info->num,
 291                                 VIRTIO_MMIO_VRING_ALIGN));
 292                 /* Already smallest possible allocation? */
 293                 if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
 294                         err = -ENOMEM;
 295                         goto error_alloc_pages;
 296                 }
 297
 298                 info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
 299                 if (info->queue)
 300                         break;
 301
 302                 info->num /= 2;
 303         }
 304
 305         /* Activate the queue */
 306         writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
 307         writel(VIRTIO_MMIO_VRING_ALIGN,
 308                         vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
 309         writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
 310                         vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 311
 312         /* Create the vring */
 313         vq = vring_new_virtqueue(info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
 314                                  true, info->queue, vm_notify, callback, name);
 315         if (!vq) {
 316                 err = -ENOMEM;
 317                 goto error_new_virtqueue;
 318         }
 319
 320         vq->priv = info;
 321         info->vq = vq;
 322
 323         spin_lock_irqsave(&vm_dev->lock, flags);
 324         list_add(&info->node, &vm_dev->virtqueues);
 325         spin_unlock_irqrestore(&vm_dev->lock, flags);
 326
 327         return vq;
 328
 329 error_new_virtqueue:
 330         writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 331         free_pages_exact(info->queue, size);
 332 error_alloc_pages:
 333         kfree(info);
 334 error_kmalloc:
 335 error_available:
 336         return ERR_PTR(err);
 337 }
 338
 339 static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 340                        struct virtqueue *vqs[],
 341                        vq_callback_t *callbacks[],
 342                        const char *names[])
 343 {
 344         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 345         unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
 346         int i, err;
 347
 348         err = request_irq(irq, vm_interrupt, IRQF_SHARED,
 349                         dev_name(&vdev->dev), vm_dev);
 350         if (err)
 351                 return err;
 352
 353         for (i = 0; i < nvqs; ++i) {
 354                 vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
 355                 if (IS_ERR(vqs[i])) {
 356                         vm_del_vqs(vdev);
 357                         return PTR_ERR(vqs[i]);
 358                 }
 359         }
 360
 361         return 0;
 362 }
 363
 364 static const char *vm_bus_name(struct virtio_device *vdev)
 365 {
 366         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 367
 368         return vm_dev->pdev->name;
 369 }
 370
 371 static struct virtio_config_ops virtio_mmio_config_ops = {
 372         .get            = vm_get,
 373         .set            = vm_set,
 374         .get_status     = vm_get_status,
 375         .set_status     = vm_set_status,
 376         .reset          = vm_reset,
 377         .find_vqs       = vm_find_vqs,
 378         .del_vqs        = vm_del_vqs,
 379         .get_features   = vm_get_features,
 380         .finalize_features = vm_finalize_features,
 381         .bus_name       = vm_bus_name,
 382 };
 383
 384
 385
 386 /* Platform device */
 387
 388 static int __devinit virtio_mmio_probe(struct platform_device *pdev)
 389 {
 390         struct virtio_mmio_device *vm_dev;
 391         struct resource *mem;
 392         unsigned long magic;
 393
 394         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 395         if (!mem)
 396                 return -EINVAL;
 397
 398         if (!devm_request_mem_region(&pdev->dev, mem->start,
 399                         resource_size(mem), pdev->name))
 400                 return -EBUSY;
 401
 402         vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
 403         if (!vm_dev)
 404                 return  -ENOMEM;
 405
 406         vm_dev->vdev.dev.parent = &pdev->dev;
 407         vm_dev->vdev.config = &virtio_mmio_config_ops;
 408         vm_dev->pdev = pdev;
 409         INIT_LIST_HEAD(&vm_dev->virtqueues);
 410         spin_lock_init(&vm_dev->lock);
 411
 412         vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
 413         if (vm_dev->base == NULL)
 414                 return -EFAULT;
 415
 416         /* Check magic value */
 417         magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 418         if (memcmp(&magic, "virt", 4) != 0) {
 419                 dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
 420                 return -ENODEV;
 421         }
 422
 423         /* Check device version */
 424         vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
 425         if (vm_dev->version != 1) {
 426                 dev_err(&pdev->dev, "Version %ld not supported!\n",
 427                                 vm_dev->version);
 428                 return -ENXIO;
 429         }
 430
 431         vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
 432         vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 433
 434         writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 435
 436         platform_set_drvdata(pdev, vm_dev);
 437
 438         return register_virtio_device(&vm_dev->vdev);
 439 }
 440
 441 static int __devexit virtio_mmio_remove(struct platform_device *pdev)
 442 {
 443         struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
 444
 445         unregister_virtio_device(&vm_dev->vdev);
 446
 447         return 0;
 448 }
 449
 450
 451
 452 /* Platform driver */
 453
 454 static struct of_device_id virtio_mmio_match[] = {
 455         { .compatible = "virtio,mmio", },
 456         {},
 457 };
 458 MODULE_DEVICE_TABLE(of, virtio_mmio_match);
 459
 460 static struct platform_driver virtio_mmio_driver = {
 461         .probe          = virtio_mmio_probe,
 462         .remove         = __devexit_p(virtio_mmio_remove),
 463         .driver         = {
 464                 .name   = "virtio-mmio",
 465                 .owner  = THIS_MODULE,
 466                 .of_match_table = virtio_mmio_match,
 467         },
 468 };
 469
 470 static int __init virtio_mmio_init(void)
 471 {
 472         return platform_driver_register(&virtio_mmio_driver);
 473 }
 474
 475 static void __exit virtio_mmio_exit(void)
 476 {
 477         platform_driver_unregister(&virtio_mmio_driver);
 478 }
 479
 480 module_init(virtio_mmio_init);
 481 module_exit(virtio_mmio_exit);
 482
 483 MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
 484 MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
 485 MODULE_LICENSE("GPL");