1/*
2 * Virtio memory mapped device driver
3 *
4 * Copyright 2011-2014, 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 * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
54 *
55 * This work is licensed under the terms of the GNU GPL, version 2 or later.
56 * See the COPYING file in the top-level directory.
57 */
58
59#define pr_fmt(fmt) "virtio-mmio: " fmt
60
61#include <linux/acpi.h>
62#include <linux/highmem.h>
63#include <linux/interrupt.h>
64#include <linux/io.h>
65#include <linux/list.h>
66#include <linux/module.h>
67#include <linux/platform_device.h>
68#include <linux/slab.h>
69#include <linux/spinlock.h>
70#include <linux/virtio.h>
71#include <linux/virtio_config.h>
72#include <linux/virtio_mmio.h>
73#include <linux/virtio_ring.h>
74
75
76
77/* The alignment to use between consumer and producer parts of vring.
78 * Currently hardcoded to the page size. */
79#define VIRTIO_MMIO_VRING_ALIGN		PAGE_SIZE
80
81
82
83#define to_virtio_mmio_device(_plat_dev) \
84	container_of(_plat_dev, struct virtio_mmio_device, vdev)
85
86struct virtio_mmio_device {
87	struct virtio_device vdev;
88	struct platform_device *pdev;
89
90	void __iomem *base;
91	unsigned long version;
92
93	/* a list of queues so we can dispatch IRQs */
94	spinlock_t lock;
95	struct list_head virtqueues;
96};
97
98struct virtio_mmio_vq_info {
99	/* the actual virtqueue */
100	struct virtqueue *vq;
101
102	/* the number of entries in the queue */
103	unsigned int num;
104
105	/* the virtual address of the ring queue */
106	void *queue;
107
108	/* the list node for the virtqueues list */
109	struct list_head node;
110};
111
112
113
114/* Configuration interface */
115
116static u64 vm_get_features(struct virtio_device *vdev)
117{
118	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
119	u64 features;
120
121	writel(1, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
122	features = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
123	features <<= 32;
124
125	writel(0, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
126	features |= readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
127
128	return features;
129}
130
131static int vm_finalize_features(struct virtio_device *vdev)
132{
133	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
134
135	/* Give virtio_ring a chance to accept features. */
136	vring_transport_features(vdev);
137
138	/* Make sure there is are no mixed devices */
139	if (vm_dev->version == 2 &&
140			!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
141		dev_err(&vdev->dev, "New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
142		return -EINVAL;
143	}
144
145	writel(1, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
146	writel((u32)(vdev->features >> 32),
147			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
148
149	writel(0, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
150	writel((u32)vdev->features,
151			vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
152
153	return 0;
154}
155
156static void vm_get(struct virtio_device *vdev, unsigned offset,
157		   void *buf, unsigned len)
158{
159	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
160	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
161	u8 b;
162	__le16 w;
163	__le32 l;
164
165	if (vm_dev->version == 1) {
166		u8 *ptr = buf;
167		int i;
168
169		for (i = 0; i < len; i++)
170			ptr[i] = readb(base + offset + i);
171		return;
172	}
173
174	switch (len) {
175	case 1:
176		b = readb(base + offset);
177		memcpy(buf, &b, sizeof b);
178		break;
179	case 2:
180		w = cpu_to_le16(readw(base + offset));
181		memcpy(buf, &w, sizeof w);
182		break;
183	case 4:
184		l = cpu_to_le32(readl(base + offset));
185		memcpy(buf, &l, sizeof l);
186		break;
187	case 8:
188		l = cpu_to_le32(readl(base + offset));
189		memcpy(buf, &l, sizeof l);
190		l = cpu_to_le32(ioread32(base + offset + sizeof l));
191		memcpy(buf + sizeof l, &l, sizeof l);
192		break;
193	default:
194		BUG();
195	}
196}
197
198static void vm_set(struct virtio_device *vdev, unsigned offset,
199		   const void *buf, unsigned len)
200{
201	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
202	void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
203	u8 b;
204	__le16 w;
205	__le32 l;
206
207	if (vm_dev->version == 1) {
208		const u8 *ptr = buf;
209		int i;
210
211		for (i = 0; i < len; i++)
212			writeb(ptr[i], base + offset + i);
213
214		return;
215	}
216
217	switch (len) {
218	case 1:
219		memcpy(&b, buf, sizeof b);
220		writeb(b, base + offset);
221		break;
222	case 2:
223		memcpy(&w, buf, sizeof w);
224		writew(le16_to_cpu(w), base + offset);
225		break;
226	case 4:
227		memcpy(&l, buf, sizeof l);
228		writel(le32_to_cpu(l), base + offset);
229		break;
230	case 8:
231		memcpy(&l, buf, sizeof l);
232		writel(le32_to_cpu(l), base + offset);
233		memcpy(&l, buf + sizeof l, sizeof l);
234		writel(le32_to_cpu(l), base + offset + sizeof l);
235		break;
236	default:
237		BUG();
238	}
239}
240
241static u32 vm_generation(struct virtio_device *vdev)
242{
243	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
244
245	if (vm_dev->version == 1)
246		return 0;
247	else
248		return readl(vm_dev->base + VIRTIO_MMIO_CONFIG_GENERATION);
249}
250
251static u8 vm_get_status(struct virtio_device *vdev)
252{
253	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
254
255	return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
256}
257
258static void vm_set_status(struct virtio_device *vdev, u8 status)
259{
260	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
261
262	/* We should never be setting status to 0. */
263	BUG_ON(status == 0);
264
265	writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
266}
267
268static void vm_reset(struct virtio_device *vdev)
269{
270	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
271
272	/* 0 status means a reset. */
273	writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
274}
275
276
277
278/* Transport interface */
279
280/* the notify function used when creating a virt queue */
281static bool vm_notify(struct virtqueue *vq)
282{
283	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
284
285	/* We write the queue's selector into the notification register to
286	 * signal the other end */
287	writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
288	return true;
289}
290
291/* Notify all virtqueues on an interrupt. */
292static irqreturn_t vm_interrupt(int irq, void *opaque)
293{
294	struct virtio_mmio_device *vm_dev = opaque;
295	struct virtio_mmio_vq_info *info;
296	unsigned long status;
297	unsigned long flags;
298	irqreturn_t ret = IRQ_NONE;
299
300	/* Read and acknowledge interrupts */
301	status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
302	writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
303
304	if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
305		virtio_config_changed(&vm_dev->vdev);
306		ret = IRQ_HANDLED;
307	}
308
309	if (likely(status & VIRTIO_MMIO_INT_VRING)) {
310		spin_lock_irqsave(&vm_dev->lock, flags);
311		list_for_each_entry(info, &vm_dev->virtqueues, node)
312			ret |= vring_interrupt(irq, info->vq);
313		spin_unlock_irqrestore(&vm_dev->lock, flags);
314	}
315
316	return ret;
317}
318
319
320
321static void vm_del_vq(struct virtqueue *vq)
322{
323	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
324	struct virtio_mmio_vq_info *info = vq->priv;
325	unsigned long flags, size;
326	unsigned int index = vq->index;
327
328	spin_lock_irqsave(&vm_dev->lock, flags);
329	list_del(&info->node);
330	spin_unlock_irqrestore(&vm_dev->lock, flags);
331
332	vring_del_virtqueue(vq);
333
334	/* Select and deactivate the queue */
335	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
336	if (vm_dev->version == 1) {
337		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
338	} else {
339		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
340		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
341	}
342
343	size = PAGE_ALIGN(vring_size(info->num, VIRTIO_MMIO_VRING_ALIGN));
344	free_pages_exact(info->queue, size);
345	kfree(info);
346}
347
348static void vm_del_vqs(struct virtio_device *vdev)
349{
350	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
351	struct virtqueue *vq, *n;
352
353	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
354		vm_del_vq(vq);
355
356	free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
357}
358
359
360
361static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
362				  void (*callback)(struct virtqueue *vq),
363				  const char *name)
364{
365	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
366	struct virtio_mmio_vq_info *info;
367	struct virtqueue *vq;
368	unsigned long flags, size;
369	int err;
370
371	if (!name)
372		return NULL;
373
374	/* Select the queue we're interested in */
375	writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
376
377	/* Queue shouldn't already be set up. */
378	if (readl(vm_dev->base + (vm_dev->version == 1 ?
379			VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
380		err = -ENOENT;
381		goto error_available;
382	}
383
384	/* Allocate and fill out our active queue description */
385	info = kmalloc(sizeof(*info), GFP_KERNEL);
386	if (!info) {
387		err = -ENOMEM;
388		goto error_kmalloc;
389	}
390
391	/* Allocate pages for the queue - start with a queue as big as
392	 * possible (limited by maximum size allowed by device), drop down
393	 * to a minimal size, just big enough to fit descriptor table
394	 * and two rings (which makes it "alignment_size * 2")
395	 */
396	info->num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
397
398	/* If the device reports a 0 entry queue, we won't be able to
399	 * use it to perform I/O, and vring_new_virtqueue() can't create
400	 * empty queues anyway, so don't bother to set up the device.
401	 */
402	if (info->num == 0) {
403		err = -ENOENT;
404		goto error_alloc_pages;
405	}
406
407	while (1) {
408		size = PAGE_ALIGN(vring_size(info->num,
409				VIRTIO_MMIO_VRING_ALIGN));
410		/* Did the last iter shrink the queue below minimum size? */
411		if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
412			err = -ENOMEM;
413			goto error_alloc_pages;
414		}
415
416		info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
417		if (info->queue)
418			break;
419
420		info->num /= 2;
421	}
422
423	/* Create the vring */
424	vq = vring_new_virtqueue(index, info->num, VIRTIO_MMIO_VRING_ALIGN, vdev,
425				 true, info->queue, vm_notify, callback, name);
426	if (!vq) {
427		err = -ENOMEM;
428		goto error_new_virtqueue;
429	}
430
431	/* Activate the queue */
432	writel(info->num, vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
433	if (vm_dev->version == 1) {
434		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
435		writel(virt_to_phys(info->queue) >> PAGE_SHIFT,
436				vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
437	} else {
438		u64 addr;
439
440		addr = virt_to_phys(info->queue);
441		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
442		writel((u32)(addr >> 32),
443				vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
444
445		addr = virt_to_phys(virtqueue_get_avail(vq));
446		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
447		writel((u32)(addr >> 32),
448				vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
449
450		addr = virt_to_phys(virtqueue_get_used(vq));
451		writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
452		writel((u32)(addr >> 32),
453				vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
454
455		writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
456	}
457
458	vq->priv = info;
459	info->vq = vq;
460
461	spin_lock_irqsave(&vm_dev->lock, flags);
462	list_add(&info->node, &vm_dev->virtqueues);
463	spin_unlock_irqrestore(&vm_dev->lock, flags);
464
465	return vq;
466
467error_new_virtqueue:
468	if (vm_dev->version == 1) {
469		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
470	} else {
471		writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
472		WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
473	}
474	free_pages_exact(info->queue, size);
475error_alloc_pages:
476	kfree(info);
477error_kmalloc:
478error_available:
479	return ERR_PTR(err);
480}
481
482static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
483		       struct virtqueue *vqs[],
484		       vq_callback_t *callbacks[],
485		       const char *names[])
486{
487	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
488	unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
489	int i, err;
490
491	err = request_irq(irq, vm_interrupt, IRQF_SHARED,
492			dev_name(&vdev->dev), vm_dev);
493	if (err)
494		return err;
495
496	for (i = 0; i < nvqs; ++i) {
497		vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
498		if (IS_ERR(vqs[i])) {
499			vm_del_vqs(vdev);
500			return PTR_ERR(vqs[i]);
501		}
502	}
503
504	return 0;
505}
506
507static const char *vm_bus_name(struct virtio_device *vdev)
508{
509	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
510
511	return vm_dev->pdev->name;
512}
513
514static const struct virtio_config_ops virtio_mmio_config_ops = {
515	.get		= vm_get,
516	.set		= vm_set,
517	.generation	= vm_generation,
518	.get_status	= vm_get_status,
519	.set_status	= vm_set_status,
520	.reset		= vm_reset,
521	.find_vqs	= vm_find_vqs,
522	.del_vqs	= vm_del_vqs,
523	.get_features	= vm_get_features,
524	.finalize_features = vm_finalize_features,
525	.bus_name	= vm_bus_name,
526};
527
528
529
530/* Platform device */
531
532static int virtio_mmio_probe(struct platform_device *pdev)
533{
534	struct virtio_mmio_device *vm_dev;
535	struct resource *mem;
536	unsigned long magic;
537
538	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
539	if (!mem)
540		return -EINVAL;
541
542	if (!devm_request_mem_region(&pdev->dev, mem->start,
543			resource_size(mem), pdev->name))
544		return -EBUSY;
545
546	vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
547	if (!vm_dev)
548		return  -ENOMEM;
549
550	vm_dev->vdev.dev.parent = &pdev->dev;
551	vm_dev->vdev.config = &virtio_mmio_config_ops;
552	vm_dev->pdev = pdev;
553	INIT_LIST_HEAD(&vm_dev->virtqueues);
554	spin_lock_init(&vm_dev->lock);
555
556	vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
557	if (vm_dev->base == NULL)
558		return -EFAULT;
559
560	/* Check magic value */
561	magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
562	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
563		dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
564		return -ENODEV;
565	}
566
567	/* Check device version */
568	vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
569	if (vm_dev->version < 1 || vm_dev->version > 2) {
570		dev_err(&pdev->dev, "Version %ld not supported!\n",
571				vm_dev->version);
572		return -ENXIO;
573	}
574
575	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
576	if (vm_dev->vdev.id.device == 0) {
577		/*
578		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
579		 * with no function. End probing now with no error reported.
580		 */
581		return -ENODEV;
582	}
583	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
584
585	if (vm_dev->version == 1)
586		writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
587
588	platform_set_drvdata(pdev, vm_dev);
589
590	return register_virtio_device(&vm_dev->vdev);
591}
592
593static int virtio_mmio_remove(struct platform_device *pdev)
594{
595	struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
596
597	unregister_virtio_device(&vm_dev->vdev);
598
599	return 0;
600}
601
602
603
604/* Devices list parameter */
605
606#if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
607
608static struct device vm_cmdline_parent = {
609	.init_name = "virtio-mmio-cmdline",
610};
611
612static int vm_cmdline_parent_registered;
613static int vm_cmdline_id;
614
615static int vm_cmdline_set(const char *device,
616		const struct kernel_param *kp)
617{
618	int err;
619	struct resource resources[2] = {};
620	char *str;
621	long long int base, size;
622	unsigned int irq;
623	int processed, consumed = 0;
624	struct platform_device *pdev;
625
626	/* Consume "size" part of the command line parameter */
627	size = memparse(device, &str);
628
629	/* Get "@<base>:<irq>[:<id>]" chunks */
630	processed = sscanf(str, "@%lli:%u%n:%d%n",
631			&base, &irq, &consumed,
632			&vm_cmdline_id, &consumed);
633
634	/*
635	 * sscanf() must processes at least 2 chunks; also there
636	 * must be no extra characters after the last chunk, so
637	 * str[consumed] must be '\0'
638	 */
639	if (processed < 2 || str[consumed])
640		return -EINVAL;
641
642	resources[0].flags = IORESOURCE_MEM;
643	resources[0].start = base;
644	resources[0].end = base + size - 1;
645
646	resources[1].flags = IORESOURCE_IRQ;
647	resources[1].start = resources[1].end = irq;
648
649	if (!vm_cmdline_parent_registered) {
650		err = device_register(&vm_cmdline_parent);
651		if (err) {
652			pr_err("Failed to register parent device!\n");
653			return err;
654		}
655		vm_cmdline_parent_registered = 1;
656	}
657
658	pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
659		       vm_cmdline_id,
660		       (unsigned long long)resources[0].start,
661		       (unsigned long long)resources[0].end,
662		       (int)resources[1].start);
663
664	pdev = platform_device_register_resndata(&vm_cmdline_parent,
665			"virtio-mmio", vm_cmdline_id++,
666			resources, ARRAY_SIZE(resources), NULL, 0);
667	if (IS_ERR(pdev))
668		return PTR_ERR(pdev);
669
670	return 0;
671}
672
673static int vm_cmdline_get_device(struct device *dev, void *data)
674{
675	char *buffer = data;
676	unsigned int len = strlen(buffer);
677	struct platform_device *pdev = to_platform_device(dev);
678
679	snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
680			pdev->resource[0].end - pdev->resource[0].start + 1ULL,
681			(unsigned long long)pdev->resource[0].start,
682			(unsigned long long)pdev->resource[1].start,
683			pdev->id);
684	return 0;
685}
686
687static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
688{
689	buffer[0] = '\0';
690	device_for_each_child(&vm_cmdline_parent, buffer,
691			vm_cmdline_get_device);
692	return strlen(buffer) + 1;
693}
694
695static const struct kernel_param_ops vm_cmdline_param_ops = {
696	.set = vm_cmdline_set,
697	.get = vm_cmdline_get,
698};
699
700device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
701
702static int vm_unregister_cmdline_device(struct device *dev,
703		void *data)
704{
705	platform_device_unregister(to_platform_device(dev));
706
707	return 0;
708}
709
710static void vm_unregister_cmdline_devices(void)
711{
712	if (vm_cmdline_parent_registered) {
713		device_for_each_child(&vm_cmdline_parent, NULL,
714				vm_unregister_cmdline_device);
715		device_unregister(&vm_cmdline_parent);
716		vm_cmdline_parent_registered = 0;
717	}
718}
719
720#else
721
722static void vm_unregister_cmdline_devices(void)
723{
724}
725
726#endif
727
728/* Platform driver */
729
730static struct of_device_id virtio_mmio_match[] = {
731	{ .compatible = "virtio,mmio", },
732	{},
733};
734MODULE_DEVICE_TABLE(of, virtio_mmio_match);
735
736#ifdef CONFIG_ACPI
737static const struct acpi_device_id virtio_mmio_acpi_match[] = {
738	{ "LNRO0005", },
739	{ }
740};
741MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
742#endif
743
744static struct platform_driver virtio_mmio_driver = {
745	.probe		= virtio_mmio_probe,
746	.remove		= virtio_mmio_remove,
747	.driver		= {
748		.name	= "virtio-mmio",
749		.of_match_table	= virtio_mmio_match,
750		.acpi_match_table = ACPI_PTR(virtio_mmio_acpi_match),
751	},
752};
753
754static int __init virtio_mmio_init(void)
755{
756	return platform_driver_register(&virtio_mmio_driver);
757}
758
759static void __exit virtio_mmio_exit(void)
760{
761	platform_driver_unregister(&virtio_mmio_driver);
762	vm_unregister_cmdline_devices();
763}
764
765module_init(virtio_mmio_init);
766module_exit(virtio_mmio_exit);
767
768MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
769MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
770MODULE_LICENSE("GPL");
771