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 index of the queue */
 135        int queue_index;
 136
 137        /* the virtual address of the ring queue */
 138        void *queue;
 139
 140        /* the list node for the virtqueues list */
 141        struct list_head node;
 142};
 143
 144
 145
 146/* Configuration interface */
 147
 148static u32 vm_get_features(struct virtio_device *vdev)
 149{
 150        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 151
 152        /* TODO: Features > 32 bits */
 153        writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
 154
 155        return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
 156}
 157
 158static void vm_finalize_features(struct virtio_device *vdev)
 159{
 160        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 161        int i;
 162
 163        /* Give virtio_ring a chance to accept features. */
 164        vring_transport_features(vdev);
 165
 166        for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
 167                writel(i, vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES_SEL);
 168                writel(vdev->features[i],
 169                                vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
 170        }
 171}
 172
 173static void vm_get(struct virtio_device *vdev, unsigned offset,
 174                   void *buf, unsigned len)
 175{
 176        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 177        u8 *ptr = buf;
 178        int i;
 179
 180        for (i = 0; i < len; i++)
 181                ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 182}
 183
 184static void vm_set(struct virtio_device *vdev, unsigned offset,
 185                   const void *buf, unsigned len)
 186{
 187        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 188        const u8 *ptr = buf;
 189        int i;
 190
 191        for (i = 0; i < len; i++)
 192                writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
 193}
 194
 195static u8 vm_get_status(struct virtio_device *vdev)
 196{
 197        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 198
 199        return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
 200}
 201
 202static void vm_set_status(struct virtio_device *vdev, u8 status)
 203{
 204        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 205
 206        /* We should never be setting status to 0. */
 207        BUG_ON(status == 0);
 208
 209        writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
 210}
 211
 212static void vm_reset(struct virtio_device *vdev)
 213{
 214        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 215
 216        /* 0 status means a reset. */
 217        writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
 218}
 219
 220
 221
 222/* Transport interface */
 223
 224/* the notify function used when creating a virt queue */
 225static void vm_notify(struct virtqueue *vq)
 226{
 227        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 228        struct virtio_mmio_vq_info *info = vq->priv;
 229
 230        /* We write the queue's selector into the notification register to
 231         * signal the other end */
 232        writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
 233}
 234
 235/* Notify all virtqueues on an interrupt. */
 236static irqreturn_t vm_interrupt(int irq, void *opaque)
 237{
 238        struct virtio_mmio_device *vm_dev = opaque;
 239        struct virtio_mmio_vq_info *info;
 240        struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver,
 241                        struct virtio_driver, driver);
 242        unsigned long status;
 243        unsigned long flags;
 244        irqreturn_t ret = IRQ_NONE;
 245
 246        /* Read and acknowledge interrupts */
 247        status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
 248        writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
 249
 250        if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)
 251                        && vdrv && vdrv->config_changed) {
 252                vdrv->config_changed(&vm_dev->vdev);
 253                ret = IRQ_HANDLED;
 254        }
 255
 256        if (likely(status & VIRTIO_MMIO_INT_VRING)) {
 257                spin_lock_irqsave(&vm_dev->lock, flags);
 258                list_for_each_entry(info, &vm_dev->virtqueues, node)
 259                        ret |= vring_interrupt(irq, info->vq);
 260                spin_unlock_irqrestore(&vm_dev->lock, flags);
 261        }
 262
 263        return ret;
 264}
 265
 266
 267
 268static void vm_del_vq(struct virtqueue *vq)
 269{
 270        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
 271        struct virtio_mmio_vq_info *info = vq->priv;
 272        unsigned long flags, size;
 273
 274        spin_lock_irqsave(&vm_dev->lock, flags);
 275        list_del(&info->node);
 276        spin_unlock_irqrestore(&vm_dev->lock, flags);
 277
 278        vring_del_virtqueue(vq);
 279
 280        /* Select and deactivate the queue */
 281        writel(info->queue_index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
 282        writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 283
 284        size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
 285        free_pages_exact(info->queue, size);
 286        kfree(info);
 287}
 288
 289static void vm_del_vqs(struct virtio_device *vdev)
 290{
 291        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 292        struct virtqueue *vq, *n;
 293
 294        list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 295                vm_del_vq(vq);
 296
 297        free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
 298}
 299
 300
 301
 302static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
 303                                  void (*callback)(struct virtqueue *vq),
 304                                  const char *name)
 305{
 306        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 307        struct virtio_mmio_vq_info *info;
 308        struct virtqueue *vq;
 309        unsigned long flags, size;
 310        int err;
 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        info->queue_index = index;
 328
 329        /* Allocate pages for the queue - start with a queue as big as
 330         * possible (limited by maximum size allowed by device), drop down
 331         * to a minimal size, just big enough to fit descriptor table
 332         * and two rings (which makes it "alignment_size * 2")
 333         */
 334        info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
 335        while (1) {
 336                size = PAGE_ALIGN(vring_size(info->num,
 337                                VIRTIO_MMIO_VRING_ALIGN));
 338                /* Already smallest possible allocation? */
 339                if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
 340                        err = -ENOMEM;
 341                        goto error_alloc_pages;
 342                }
 343
 344                info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
 345                if (info->queue)
 346                        break;
 347
 348                info->num /= 2;
 349        }
 350
 351        /* Activate the queue */
 352        writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
 353        writel(VIRTIO_MMIO_VRING_ALIGN,
 354                        vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
 355        writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
 356                        vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 357
 358        /* Create the vring */
 359        vq = vring_new_virtqueue(info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
 360                                 true, info->queue, vm_notify, callback, name);
 361        if (!vq) {
 362                err = -ENOMEM;
 363                goto error_new_virtqueue;
 364        }
 365
 366        vq->priv = info;
 367        info->vq = vq;
 368
 369        spin_lock_irqsave(&vm_dev->lock, flags);
 370        list_add(&info->node, &vm_dev->virtqueues);
 371        spin_unlock_irqrestore(&vm_dev->lock, flags);
 372
 373        return vq;
 374
 375error_new_virtqueue:
 376        writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
 377        free_pages_exact(info->queue, size);
 378error_alloc_pages:
 379        kfree(info);
 380error_kmalloc:
 381error_available:
 382        return ERR_PTR(err);
 383}
 384
 385static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 386                       struct virtqueue *vqs[],
 387                       vq_callback_t *callbacks[],
 388                       const char *names[])
 389{
 390        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 391        unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
 392        int i, err;
 393
 394        err = request_irq(irq, vm_interrupt, IRQF_SHARED,
 395                        dev_name(&vdev->dev), vm_dev);
 396        if (err)
 397                return err;
 398
 399        for (i = 0; i < nvqs; ++i) {
 400                vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
 401                if (IS_ERR(vqs[i])) {
 402                        vm_del_vqs(vdev);
 403                        return PTR_ERR(vqs[i]);
 404                }
 405        }
 406
 407        return 0;
 408}
 409
 410static const char *vm_bus_name(struct virtio_device *vdev)
 411{
 412        struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
 413
 414        return vm_dev->pdev->name;
 415}
 416
 417static struct virtio_config_ops virtio_mmio_config_ops = {
 418        .get            = vm_get,
 419        .set            = vm_set,
 420        .get_status     = vm_get_status,
 421        .set_status     = vm_set_status,
 422        .reset          = vm_reset,
 423        .find_vqs       = vm_find_vqs,
 424        .del_vqs        = vm_del_vqs,
 425        .get_features   = vm_get_features,
 426        .finalize_features = vm_finalize_features,
 427        .bus_name       = vm_bus_name,
 428};
 429
 430
 431
 432/* Platform device */
 433
 434static int __devinit virtio_mmio_probe(struct platform_device *pdev)
 435{
 436        struct virtio_mmio_device *vm_dev;
 437        struct resource *mem;
 438        unsigned long magic;
 439
 440        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 441        if (!mem)
 442                return -EINVAL;
 443
 444        if (!devm_request_mem_region(&pdev->dev, mem->start,
 445                        resource_size(mem), pdev->name))
 446                return -EBUSY;
 447
 448        vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
 449        if (!vm_dev)
 450                return  -ENOMEM;
 451
 452        vm_dev->vdev.dev.parent = &pdev->dev;
 453        vm_dev->vdev.config = &virtio_mmio_config_ops;
 454        vm_dev->pdev = pdev;
 455        INIT_LIST_HEAD(&vm_dev->virtqueues);
 456        spin_lock_init(&vm_dev->lock);
 457
 458        vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
 459        if (vm_dev->base == NULL)
 460                return -EFAULT;
 461
 462        /* Check magic value */
 463        magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
 464        if (memcmp(&magic, "virt", 4) != 0) {
 465                dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
 466                return -ENODEV;
 467        }
 468
 469        /* Check device version */
 470        vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
 471        if (vm_dev->version != 1) {
 472                dev_err(&pdev->dev, "Version %ld not supported!\n",
 473                                vm_dev->version);
 474                return -ENXIO;
 475        }
 476
 477        vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
 478        vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
 479
 480        writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
 481
 482        platform_set_drvdata(pdev, vm_dev);
 483
 484        return register_virtio_device(&vm_dev->vdev);
 485}
 486
 487static int __devexit virtio_mmio_remove(struct platform_device *pdev)
 488{
 489        struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
 490
 491        unregister_virtio_device(&vm_dev->vdev);
 492
 493        return 0;
 494}
 495
 496
 497
 498/* Devices list parameter */
 499
 500#if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
 501
 502static struct device vm_cmdline_parent = {
 503        .init_name = "virtio-mmio-cmdline",
 504};
 505
 506static int vm_cmdline_parent_registered;
 507static int vm_cmdline_id;
 508
 509static int vm_cmdline_set(const char *device,
 510                const struct kernel_param *kp)
 511{
 512        int err;
 513        struct resource resources[2] = {};
 514        char *str;
 515        long long int base;
 516        int processed, consumed = 0;
 517        struct platform_device *pdev;
 518
 519        resources[0].flags = IORESOURCE_MEM;
 520        resources[1].flags = IORESOURCE_IRQ;
 521
 522        resources[0].end = memparse(device, &str) - 1;
 523
 524        processed = sscanf(str, "@%lli:%u%n:%d%n",
 525                        &base, &resources[1].start, &consumed,
 526                        &vm_cmdline_id, &consumed);
 527
 528        if (processed < 2 || processed > 3 || str[consumed])
 529                return -EINVAL;
 530
 531        resources[0].start = base;
 532        resources[0].end += base;
 533        resources[1].end = resources[1].start;
 534
 535        if (!vm_cmdline_parent_registered) {
 536                err = device_register(&vm_cmdline_parent);
 537                if (err) {
 538                        pr_err("Failed to register parent device!\n");
 539                        return err;
 540                }
 541                vm_cmdline_parent_registered = 1;
 542        }
 543
 544        pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
 545                       vm_cmdline_id,
 546                       (unsigned long long)resources[0].start,
 547                       (unsigned long long)resources[0].end,
 548                       (int)resources[1].start);
 549
 550        pdev = platform_device_register_resndata(&vm_cmdline_parent,
 551                        "virtio-mmio", vm_cmdline_id++,
 552                        resources, ARRAY_SIZE(resources), NULL, 0);
 553        if (IS_ERR(pdev))
 554                return PTR_ERR(pdev);
 555
 556        return 0;
 557}
 558
 559static int vm_cmdline_get_device(struct device *dev, void *data)
 560{
 561        char *buffer = data;
 562        unsigned int len = strlen(buffer);
 563        struct platform_device *pdev = to_platform_device(dev);
 564
 565        snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
 566                        pdev->resource[0].end - pdev->resource[0].start + 1ULL,
 567                        (unsigned long long)pdev->resource[0].start,
 568                        (unsigned long long)pdev->resource[1].start,
 569                        pdev->id);
 570        return 0;
 571}
 572
 573static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
 574{
 575        buffer[0] = '\0';
 576        device_for_each_child(&vm_cmdline_parent, buffer,
 577                        vm_cmdline_get_device);
 578        return strlen(buffer) + 1;
 579}
 580
 581static struct kernel_param_ops vm_cmdline_param_ops = {
 582        .set = vm_cmdline_set,
 583        .get = vm_cmdline_get,
 584};
 585
 586device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
 587
 588static int vm_unregister_cmdline_device(struct device *dev,
 589                void *data)
 590{
 591        platform_device_unregister(to_platform_device(dev));
 592
 593        return 0;
 594}
 595
 596static void vm_unregister_cmdline_devices(void)
 597{
 598        if (vm_cmdline_parent_registered) {
 599                device_for_each_child(&vm_cmdline_parent, NULL,
 600                                vm_unregister_cmdline_device);
 601                device_unregister(&vm_cmdline_parent);
 602                vm_cmdline_parent_registered = 0;
 603        }
 604}
 605
 606#else
 607
 608static void vm_unregister_cmdline_devices(void)
 609{
 610}
 611
 612#endif
 613
 614/* Platform driver */
 615
 616static struct of_device_id virtio_mmio_match[] = {
 617        { .compatible = "virtio,mmio", },
 618        {},
 619};
 620MODULE_DEVICE_TABLE(of, virtio_mmio_match);
 621
 622static struct platform_driver virtio_mmio_driver = {
 623        .probe          = virtio_mmio_probe,
 624        .remove         = __devexit_p(virtio_mmio_remove),
 625        .driver         = {
 626                .name   = "virtio-mmio",
 627                .owner  = THIS_MODULE,
 628                .of_match_table = virtio_mmio_match,
 629        },
 630};
 631
 632static int __init virtio_mmio_init(void)
 633{
 634        return platform_driver_register(&virtio_mmio_driver);
 635}
 636
 637static void __exit virtio_mmio_exit(void)
 638{
 639        platform_driver_unregister(&virtio_mmio_driver);
 640        vm_unregister_cmdline_devices();
 641}
 642
 643module_init(virtio_mmio_init);
 644module_exit(virtio_mmio_exit);
 645
 646MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
 647MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
 648MODULE_LICENSE("GPL");
 649
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