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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 
118 
119  void __iomem *base;
120  unsigned long version;
121 
122  /* a list of queues so we can dispatch IRQs */
125 };
126 
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 
145 static 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 */
151 
152  return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
153 }
154 
155 static 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. */
162 
163  for (i = 0; i < ARRAY_SIZE(vdev->features); i++) {
165  writel(vdev->features[i],
166  vm_dev->base + VIRTIO_MMIO_GUEST_FEATURES);
167  }
168 }
169 
170 static 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 
181 static 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 
192 static 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 
199 static 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 
209 static 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 */
222 static 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 */
229 }
230 
231 /* Notify all virtqueues on an interrupt. */
232 static 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;
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 
264 static 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 
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 
286 static 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 
299 static 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,
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);
363  vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
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 
384 error_new_virtqueue:
385  writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
386  free_pages_exact(info->queue, size);
387 error_alloc_pages:
388  kfree(info);
389 error_kmalloc:
390 error_available:
391  return ERR_PTR(err);
392 }
393 
394 static 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 
419 static 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 
426 static 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 
443 static 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 
490 
491  platform_set_drvdata(pdev, vm_dev);
492 
493  return register_virtio_device(&vm_dev->vdev);
494 }
495 
496 static 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 
511 static struct device vm_cmdline_parent = {
512  .init_name = "virtio-mmio-cmdline",
513 };
514 
515 static int vm_cmdline_parent_registered;
516 static int vm_cmdline_id;
517 
518 static 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 
568 static 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 
582 static 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 
590 static struct kernel_param_ops vm_cmdline_param_ops = {
591  .set = vm_cmdline_set,
592  .get = vm_cmdline_get,
593 };
594 
595 device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
596 
597 static int vm_unregister_cmdline_device(struct device *dev,
598  void *data)
599 {
601 
602  return 0;
603 }
604 
605 static 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 
617 static void vm_unregister_cmdline_devices(void)
618 {
619 }
620 
621 #endif
622 
623 /* Platform driver */
624 
625 static struct of_device_id virtio_mmio_match[] = {
626  { .compatible = "virtio,mmio", },
627  {},
628 };
629 MODULE_DEVICE_TABLE(of, virtio_mmio_match);
630 
631 static 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 
641 static int __init virtio_mmio_init(void)
642 {
643  return platform_driver_register(&virtio_mmio_driver);
644 }
645 
646 static void __exit virtio_mmio_exit(void)
647 {
648  platform_driver_unregister(&virtio_mmio_driver);
649  vm_unregister_cmdline_devices();
650 }
651 
652 module_init(virtio_mmio_init);
653 module_exit(virtio_mmio_exit);
654 
655 MODULE_AUTHOR("Pawel Moll <[email protected]>");
656 MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
657 MODULE_LICENSE("GPL");