2 * Virtio memory mapped device driver
4 * Copyright 2011, ARM Ltd.
6 * This module allows virtio devices to be used over a virtual, memory mapped
9 * The guest device(s) may be instantiated in one of three equivalent ways:
11 * 1. Static platform device in board's code, eg.:
13 * static struct platform_device v2m_virtio_device = {
14 * .name = "virtio-mmio",
17 * .resource = (struct resource []) {
19 * .start = 0x1001e000,
21 * .flags = IORESOURCE_MEM,
25 * .flags = IORESOURCE_IRQ,
30 * 2. Device Tree node, eg.:
32 * virtio_block@1e000 {
33 * compatible = "virtio,mmio";
34 * reg = <0x1e000 0x100>;
38 * 3. Kernel module (or command line) parameter. Can be used more than once -
39 * one device will be created for each one. Syntax:
41 * [virtio_mmio.]device=<size>@<baseaddr>:<irq>[:<id>]
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
48 * virtio_mmio.device=0x100@0x100b0000:48 \
49 * virtio_mmio.device=1K@0x1001e000:74
53 * Registers layout (all 32-bit wide):
55 * offset d. name description
56 * ------ -- ---------------- -----------------
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
63 * 0x010 R HostFeatures Features supported by the host
64 * 0x014 W HostFeaturesSel Set of host features to access via HostFeatures
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
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
76 * 0x050 W QueueNotify Queue notifier
77 * 0x060 R InterruptStatus Interrupt status register
78 * 0x064 W InterruptACK Interrupt acknowledge register
79 * 0x070 RW Status Device status register
81 * 0x100+ RW Device-specific configuration space
83 * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
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.
89 #define pr_fmt(fmt) "virtio-mmio: " fmt
91 #include <linux/highmem.h>
92 #include <linux/interrupt.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>
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
112 #define to_virtio_mmio_device(_plat_dev) \
113 container_of(_plat_dev, struct virtio_mmio_device, vdev)
115 struct virtio_mmio_device {
116 struct virtio_device vdev;
117 struct platform_device *pdev;
120 unsigned long version;
122 /* a list of queues so we can dispatch IRQs */
124 struct list_head virtqueues;
127 struct virtio_mmio_vq_info {
128 /* the actual virtqueue */
129 struct virtqueue *vq;
131 /* the number of entries in the queue */
134 /* the virtual address of the ring queue */
137 /* the list node for the virtqueues list */
138 struct list_head node;
143 /* Configuration interface */
145 static u32 vm_get_features(struct virtio_device *vdev)
147 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
149 /* TODO: Features > 32 bits */
150 writel(0, vm_dev->base + VIRTIO_MMIO_HOST_FEATURES_SEL);
152 return readl(vm_dev->base + VIRTIO_MMIO_HOST_FEATURES);
155 static void vm_finalize_features(struct virtio_device *vdev)
157 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
160 /* Give virtio_ring a chance to accept features. */
161 vring_transport_features(vdev);
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);
170 static void vm_get(struct virtio_device *vdev, unsigned offset,
171 void *buf, unsigned len)
173 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
177 for (i = 0; i < len; i++)
178 ptr[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
181 static void vm_set(struct virtio_device *vdev, unsigned offset,
182 const void *buf, unsigned len)
184 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
188 for (i = 0; i < len; i++)
189 writeb(ptr[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
192 static u8 vm_get_status(struct virtio_device *vdev)
194 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
196 return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
199 static void vm_set_status(struct virtio_device *vdev, u8 status)
201 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
203 /* We should never be setting status to 0. */
206 writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
209 static void vm_reset(struct virtio_device *vdev)
211 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
213 /* 0 status means a reset. */
214 writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
219 /* Transport interface */
221 /* the notify function used when creating a virt queue */
222 static bool vm_notify(struct virtqueue *vq)
224 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
226 /* We write the queue's selector into the notification register to
227 * signal the other end */
228 writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
232 /* Notify all virtqueues on an interrupt. */
233 static irqreturn_t vm_interrupt(int irq, void *opaque)
235 struct virtio_mmio_device *vm_dev = opaque;
236 struct virtio_mmio_vq_info *info;
237 unsigned long status;
239 irqreturn_t ret = IRQ_NONE;
241 /* Read and acknowledge interrupts */
242 status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
243 writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
245 if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
246 virtio_config_changed(&vm_dev->vdev);
250 if (likely(status & VIRTIO_MMIO_INT_VRING)) {
251 spin_lock_irqsave(&vm_dev->lock, flags);
252 list_for_each_entry(info, &vm_dev->virtqueues, node)
253 ret |= vring_interrupt(irq, info->vq);
254 spin_unlock_irqrestore(&vm_dev->lock, flags);
262 static void vm_del_vq(struct virtqueue *vq)
264 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
265 struct virtio_mmio_vq_info *info = vq->priv;
266 unsigned long flags, size;
267 unsigned int index = vq->index;
269 spin_lock_irqsave(&vm_dev->lock, flags);
270 list_del(&info->node);
271 spin_unlock_irqrestore(&vm_dev->lock, flags);
273 vring_del_virtqueue(vq);
275 /* Select and deactivate the queue */
276 writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
277 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
279 size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
280 free_pages_exact(info->queue, size);
284 static void vm_del_vqs(struct virtio_device *vdev)
286 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
287 struct virtqueue *vq, *n;
289 list_for_each_entry_safe(vq, n, &vdev->vqs, list)
292 free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
297 static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
298 void (*callback)(struct virtqueue *vq),
301 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
302 struct virtio_mmio_vq_info *info;
303 struct virtqueue *vq;
304 unsigned long flags, size;
310 /* Select the queue we're interested in */
311 writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
313 /* Queue shouldn't already be set up. */
314 if (readl(vm_dev->base + VIRTIO_MMIO_QUEUE_PFN)) {
316 goto error_available;
319 /* Allocate and fill out our active queue description */
320 info = kmalloc(sizeof(*info), GFP_KERNEL);
326 /* Allocate pages for the queue - start with a queue as big as
327 * possible (limited by maximum size allowed by device), drop down
328 * to a minimal size, just big enough to fit descriptor table
329 * and two rings (which makes it "alignment_size * 2")
331 info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
333 /* If the device reports a 0 entry queue, we won't be able to
334 * use it to perform I/O, and vring_new_virtqueue() can't create
335 * empty queues anyway, so don't bother to set up the device.
337 if (info->num == 0) {
339 goto error_alloc_pages;
343 size = PAGE_ALIGN(vring_size(info->num,
344 VIRTIO_MMIO_VRING_ALIGN));
345 /* Did the last iter shrink the queue below minimum size? */
346 if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
348 goto error_alloc_pages;
351 info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
358 /* Activate the queue */
359 writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
360 writel(VIRTIO_MMIO_VRING_ALIGN,
361 vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
362 writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
363 vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
365 /* Create the vring */
366 vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
367 true, info->queue, vm_notify, callback, name);
370 goto error_new_virtqueue;
376 spin_lock_irqsave(&vm_dev->lock, flags);
377 list_add(&info->node, &vm_dev->virtqueues);
378 spin_unlock_irqrestore(&vm_dev->lock, flags);
383 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
384 free_pages_exact(info->queue, size);
392 static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
393 struct virtqueue *vqs[],
394 vq_callback_t *callbacks[],
397 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
398 unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
401 err = request_irq(irq, vm_interrupt, IRQF_SHARED,
402 dev_name(&vdev->dev), vm_dev);
406 for (i = 0; i < nvqs; ++i) {
407 vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
408 if (IS_ERR(vqs[i])) {
410 return PTR_ERR(vqs[i]);
417 static const char *vm_bus_name(struct virtio_device *vdev)
419 struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
421 return vm_dev->pdev->name;
424 static const struct virtio_config_ops virtio_mmio_config_ops = {
427 .get_status = vm_get_status,
428 .set_status = vm_set_status,
430 .find_vqs = vm_find_vqs,
431 .del_vqs = vm_del_vqs,
432 .get_features = vm_get_features,
433 .finalize_features = vm_finalize_features,
434 .bus_name = vm_bus_name,
439 /* Platform device */
441 static int virtio_mmio_probe(struct platform_device *pdev)
443 struct virtio_mmio_device *vm_dev;
444 struct resource *mem;
447 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
451 if (!devm_request_mem_region(&pdev->dev, mem->start,
452 resource_size(mem), pdev->name))
455 vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
459 vm_dev->vdev.dev.parent = &pdev->dev;
460 vm_dev->vdev.config = &virtio_mmio_config_ops;
462 INIT_LIST_HEAD(&vm_dev->virtqueues);
463 spin_lock_init(&vm_dev->lock);
465 vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
466 if (vm_dev->base == NULL)
469 /* Check magic value */
470 magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
471 if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
472 dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
476 /* Check device version */
477 vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
478 if (vm_dev->version != 1) {
479 dev_err(&pdev->dev, "Version %ld not supported!\n",
484 vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
485 vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
487 writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
489 platform_set_drvdata(pdev, vm_dev);
491 return register_virtio_device(&vm_dev->vdev);
494 static int virtio_mmio_remove(struct platform_device *pdev)
496 struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
498 unregister_virtio_device(&vm_dev->vdev);
505 /* Devices list parameter */
507 #if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
509 static struct device vm_cmdline_parent = {
510 .init_name = "virtio-mmio-cmdline",
513 static int vm_cmdline_parent_registered;
514 static int vm_cmdline_id;
516 static int vm_cmdline_set(const char *device,
517 const struct kernel_param *kp)
520 struct resource resources[2] = {};
522 long long int base, size;
524 int processed, consumed = 0;
525 struct platform_device *pdev;
527 /* Consume "size" part of the command line parameter */
528 size = memparse(device, &str);
530 /* Get "@<base>:<irq>[:<id>]" chunks */
531 processed = sscanf(str, "@%lli:%u%n:%d%n",
532 &base, &irq, &consumed,
533 &vm_cmdline_id, &consumed);
536 * sscanf() must processes at least 2 chunks; also there
537 * must be no extra characters after the last chunk, so
538 * str[consumed] must be '\0'
540 if (processed < 2 || str[consumed])
543 resources[0].flags = IORESOURCE_MEM;
544 resources[0].start = base;
545 resources[0].end = base + size - 1;
547 resources[1].flags = IORESOURCE_IRQ;
548 resources[1].start = resources[1].end = irq;
550 if (!vm_cmdline_parent_registered) {
551 err = device_register(&vm_cmdline_parent);
553 pr_err("Failed to register parent device!\n");
556 vm_cmdline_parent_registered = 1;
559 pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
561 (unsigned long long)resources[0].start,
562 (unsigned long long)resources[0].end,
563 (int)resources[1].start);
565 pdev = platform_device_register_resndata(&vm_cmdline_parent,
566 "virtio-mmio", vm_cmdline_id++,
567 resources, ARRAY_SIZE(resources), NULL, 0);
569 return PTR_ERR(pdev);
574 static int vm_cmdline_get_device(struct device *dev, void *data)
577 unsigned int len = strlen(buffer);
578 struct platform_device *pdev = to_platform_device(dev);
580 snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
581 pdev->resource[0].end - pdev->resource[0].start + 1ULL,
582 (unsigned long long)pdev->resource[0].start,
583 (unsigned long long)pdev->resource[1].start,
588 static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
591 device_for_each_child(&vm_cmdline_parent, buffer,
592 vm_cmdline_get_device);
593 return strlen(buffer) + 1;
596 static struct kernel_param_ops vm_cmdline_param_ops = {
597 .set = vm_cmdline_set,
598 .get = vm_cmdline_get,
601 device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
603 static int vm_unregister_cmdline_device(struct device *dev,
606 platform_device_unregister(to_platform_device(dev));
611 static void vm_unregister_cmdline_devices(void)
613 if (vm_cmdline_parent_registered) {
614 device_for_each_child(&vm_cmdline_parent, NULL,
615 vm_unregister_cmdline_device);
616 device_unregister(&vm_cmdline_parent);
617 vm_cmdline_parent_registered = 0;
623 static void vm_unregister_cmdline_devices(void)
629 /* Platform driver */
631 static struct of_device_id virtio_mmio_match[] = {
632 { .compatible = "virtio,mmio", },
635 MODULE_DEVICE_TABLE(of, virtio_mmio_match);
637 static struct platform_driver virtio_mmio_driver = {
638 .probe = virtio_mmio_probe,
639 .remove = virtio_mmio_remove,
641 .name = "virtio-mmio",
642 .owner = THIS_MODULE,
643 .of_match_table = virtio_mmio_match,
647 static int __init virtio_mmio_init(void)
649 return platform_driver_register(&virtio_mmio_driver);
652 static void __exit virtio_mmio_exit(void)
654 platform_driver_unregister(&virtio_mmio_driver);
655 vm_unregister_cmdline_devices();
658 module_init(virtio_mmio_init);
659 module_exit(virtio_mmio_exit);
661 MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
662 MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
663 MODULE_LICENSE("GPL");