drivers/virtio/virtio_mmio.c - platform/external/u-boot - Gitiles

 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
  * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
  *
  * VirtIO memory-maped I/O transport driver
  * Ported from Linux drivers/virtio/virtio_mmio.c
  */

 #include <common.h>
 #include <dm.h>
 #include <virtio_types.h>
 #include <virtio.h>
 #include <virtio_ring.h>
 #include <linux/compat.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include "virtio_mmio.h"

 static int virtio_mmio_get_config(struct udevice *udev, unsigned int offset,
 				  void *buf, unsigned int len)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);
 	void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
 	u8 b;
 	__le16 w;
 	__le32 l;

 	if (priv->version == 1) {
 		u8 *ptr = buf;
 		int i;

 		for (i = 0; i < len; i++)
 			ptr[i] = readb(base + offset + i);

 		return 0;
 	}

 	switch (len) {
 	case 1:
 		b = readb(base + offset);
 		memcpy(buf, &b, sizeof(b));
 		break;
 	case 2:
 		w = cpu_to_le16(readw(base + offset));
 		memcpy(buf, &w, sizeof(w));
 		break;
 	case 4:
 		l = cpu_to_le32(readl(base + offset));
 		memcpy(buf, &l, sizeof(l));
 		break;
 	case 8:
 		l = cpu_to_le32(readl(base + offset));
 		memcpy(buf, &l, sizeof(l));
 		l = cpu_to_le32(readl(base + offset + sizeof(l)));
 		memcpy(buf + sizeof(l), &l, sizeof(l));
 		break;
 	default:
 		WARN_ON(true);
 	}

 	return 0;
 }

 static int virtio_mmio_set_config(struct udevice *udev, unsigned int offset,
 				  const void *buf, unsigned int len)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);
 	void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
 	u8 b;
 	__le16 w;
 	__le32 l;

 	if (priv->version == 1) {
 		const u8 *ptr = buf;
 		int i;

 		for (i = 0; i < len; i++)
 			writeb(ptr[i], base + offset + i);

 		return 0;
 	}

 	switch (len) {
 	case 1:
 		memcpy(&b, buf, sizeof(b));
 		writeb(b, base + offset);
 		break;
 	case 2:
 		memcpy(&w, buf, sizeof(w));
 		writew(le16_to_cpu(w), base + offset);
 		break;
 	case 4:
 		memcpy(&l, buf, sizeof(l));
 		writel(le32_to_cpu(l), base + offset);
 		break;
 	case 8:
 		memcpy(&l, buf, sizeof(l));
 		writel(le32_to_cpu(l), base + offset);
 		memcpy(&l, buf + sizeof(l), sizeof(l));
 		writel(le32_to_cpu(l), base + offset + sizeof(l));
 		break;
 	default:
 		WARN_ON(true);
 	}

 	return 0;
 }

 static int virtio_mmio_generation(struct udevice *udev, u32 *counter)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	if (priv->version == 1)
 		*counter = 0;
 	else
 		*counter = readl(priv->base + VIRTIO_MMIO_CONFIG_GENERATION);

 	return 0;
 }

 static int virtio_mmio_get_status(struct udevice *udev, u8 *status)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	*status = readl(priv->base + VIRTIO_MMIO_STATUS) & 0xff;

 	return 0;
 }

 static int virtio_mmio_set_status(struct udevice *udev, u8 status)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	/* We should never be setting status to 0 */
 	WARN_ON(status == 0);

 	writel(status, priv->base + VIRTIO_MMIO_STATUS);

 	return 0;
 }

 static int virtio_mmio_reset(struct udevice *udev)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	/* 0 status means a reset */
 	writel(0, priv->base + VIRTIO_MMIO_STATUS);

 	return 0;
 }

 static int virtio_mmio_get_features(struct udevice *udev, u64 *features)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	writel(1, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
 	*features = readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);
 	*features <<= 32;

 	writel(0, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
 	*features |= readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);

 	return 0;
 }

 static int virtio_mmio_set_features(struct udevice *udev)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);
 	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);

 	/* Make sure there is are no mixed devices */
 	if (priv->version == 2 && uc_priv->legacy) {
 		debug("New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
 		return -EINVAL;
 	}

 	writel(1, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
 	writel((u32)(uc_priv->features >> 32),
 	       priv->base + VIRTIO_MMIO_DRIVER_FEATURES);

 	writel(0, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
 	writel((u32)uc_priv->features,
 	       priv->base + VIRTIO_MMIO_DRIVER_FEATURES);

 	return 0;
 }

 static struct virtqueue *virtio_mmio_setup_vq(struct udevice *udev,
 					      unsigned int index)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);
 	struct virtqueue *vq;
 	unsigned int num;
 	int err;

 	/* Select the queue we're interested in */
 	writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);

 	/* Queue shouldn't already be set up */
 	if (readl(priv->base + (priv->version == 1 ?
 	    VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
 		err = -ENOENT;
 		goto error_available;
 	}

 	num = readl(priv->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
 	if (num == 0) {
 		err = -ENOENT;
 		goto error_new_virtqueue;
 	}

 	/* Create the vring */
 	vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, udev);
 	if (!vq) {
 		err = -ENOMEM;
 		goto error_new_virtqueue;
 	}

 	/* Activate the queue */
 	writel(virtqueue_get_vring_size(vq),
 	       priv->base + VIRTIO_MMIO_QUEUE_NUM);
 	if (priv->version == 1) {
 		u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;

 		/*
 		 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
 		 * that doesn't fit in 32bit, fail the setup rather than
 		 * pretending to be successful.
 		 */
 		if (q_pfn >> 32) {
 			debug("platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
 			      0x1ULL << (32 + PAGE_SHIFT - 30));
 			err = -E2BIG;
 			goto error_bad_pfn;
 		}

 		writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_QUEUE_ALIGN);
 		writel(q_pfn, priv->base + VIRTIO_MMIO_QUEUE_PFN);
 	} else {
 		u64 addr;

 		addr = virtqueue_get_desc_addr(vq);
 		writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
 		writel((u32)(addr >> 32),
 		       priv->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);

 		addr = virtqueue_get_avail_addr(vq);
 		writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
 		writel((u32)(addr >> 32),
 		       priv->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);

 		addr = virtqueue_get_used_addr(vq);
 		writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_USED_LOW);
 		writel((u32)(addr >> 32),
 		       priv->base + VIRTIO_MMIO_QUEUE_USED_HIGH);

 		writel(1, priv->base + VIRTIO_MMIO_QUEUE_READY);
 	}

 	return vq;

 error_bad_pfn:
 	vring_del_virtqueue(vq);

 error_new_virtqueue:
 	if (priv->version == 1) {
 		writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
 	} else {
 		writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
 		WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
 	}

 error_available:
 	return ERR_PTR(err);
 }

 static void virtio_mmio_del_vq(struct virtqueue *vq)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(vq->vdev);
 	unsigned int index = vq->index;

 	/* Select and deactivate the queue */
 	writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);
 	if (priv->version == 1) {
 		writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
 	} else {
 		writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
 		WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
 	}

 	vring_del_virtqueue(vq);
 }

 static int virtio_mmio_del_vqs(struct udevice *udev)
 {
 	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
 	struct virtqueue *vq, *n;

 	list_for_each_entry_safe(vq, n, &uc_priv->vqs, list)
 		virtio_mmio_del_vq(vq);

 	return 0;
 }

 static int virtio_mmio_find_vqs(struct udevice *udev, unsigned int nvqs,
 				struct virtqueue *vqs[])
 {
 	int i;

 	for (i = 0; i < nvqs; ++i) {
 		vqs[i] = virtio_mmio_setup_vq(udev, i);
 		if (IS_ERR(vqs[i])) {
 			virtio_mmio_del_vqs(udev);
 			return PTR_ERR(vqs[i]);
 		}
 	}

 	return 0;
 }

 static int virtio_mmio_notify(struct udevice *udev, struct virtqueue *vq)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	/*
 	 * We write the queue's selector into the notification register
 	 * to signal the other end
 	 */
 	writel(vq->index, priv->base + VIRTIO_MMIO_QUEUE_NOTIFY);

 	return 0;
 }

 static int virtio_mmio_ofdata_to_platdata(struct udevice *udev)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);

 	priv->base = (void __iomem *)(ulong)dev_read_addr(udev);
 	if (priv->base == (void __iomem *)FDT_ADDR_T_NONE)
 		return -EINVAL;

 	return 0;
 }

 static int virtio_mmio_probe(struct udevice *udev)
 {
 	struct virtio_mmio_priv *priv = dev_get_priv(udev);
 	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
 	u32 magic;

 	/* Check magic value */
 	magic = readl(priv->base + VIRTIO_MMIO_MAGIC_VALUE);
 	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
 		debug("(%s): wrong magic value 0x%08x!\n", udev->name, magic);
 		return 0;
 	}

 	/* Check device version */
 	priv->version = readl(priv->base + VIRTIO_MMIO_VERSION);
 	if (priv->version < 1 || priv->version > 2) {
 		debug("(%s): version %d not supported!\n",
 		      udev->name, priv->version);
 		return 0;
 	}

 	/* Check device ID */
 	uc_priv->device = readl(priv->base + VIRTIO_MMIO_DEVICE_ID);
 	if (uc_priv->device == 0) {
 		/*
 		 * virtio-mmio device with an ID 0 is a (dummy) placeholder
 		 * with no function. End probing now with no error reported.
 		 */
 		return 0;
 	}
 	uc_priv->vendor = readl(priv->base + VIRTIO_MMIO_VENDOR_ID);

 	if (priv->version == 1)
 		writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);

 	debug("(%s): device (%d) vendor (%08x) version (%d)\n", udev->name,
 	      uc_priv->device, uc_priv->vendor, priv->version);

 	return 0;
 }

 static const struct dm_virtio_ops virtio_mmio_ops = {
 	.get_config	= virtio_mmio_get_config,
 	.set_config	= virtio_mmio_set_config,
 	.generation	= virtio_mmio_generation,
 	.get_status	= virtio_mmio_get_status,
 	.set_status	= virtio_mmio_set_status,
 	.reset		= virtio_mmio_reset,
 	.get_features	= virtio_mmio_get_features,
 	.set_features	= virtio_mmio_set_features,
 	.find_vqs	= virtio_mmio_find_vqs,
 	.del_vqs	= virtio_mmio_del_vqs,
 	.notify		= virtio_mmio_notify,
 };

 static const struct udevice_id virtio_mmio_ids[] = {
 	{ .compatible = "virtio,mmio" },
 	{ }
 };

 U_BOOT_DRIVER(virtio_mmio) = {
 	.name	= "virtio-mmio",
 	.id	= UCLASS_VIRTIO,
 	.of_match = virtio_mmio_ids,
 	.ops	= &virtio_mmio_ops,
 	.probe	= virtio_mmio_probe,
 	.ofdata_to_platdata = virtio_mmio_ofdata_to_platdata,
 	.priv_auto_alloc_size = sizeof(struct virtio_mmio_priv),
 };
	// SPDX-License-Identifier: GPL-2.0+
	/*
	* Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
	* Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
	*
	* VirtIO memory-maped I/O transport driver
	* Ported from Linux drivers/virtio/virtio_mmio.c
	*/

	#include <common.h>
	#include <dm.h>
	#include <virtio_types.h>
	#include <virtio.h>
	#include <virtio_ring.h>
	#include <linux/compat.h>
	#include <linux/err.h>
	#include <linux/io.h>
	#include "virtio_mmio.h"

	static int virtio_mmio_get_config(struct udevice *udev, unsigned int offset,
	void *buf, unsigned int len)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);
	void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
	u8 b;
	__le16 w;
	__le32 l;

	if (priv->version == 1) {
	u8 *ptr = buf;
	int i;

	for (i = 0; i < len; i++)
	ptr[i] = readb(base + offset + i);

	return 0;
	}

	switch (len) {
	case 1:
	b = readb(base + offset);
	memcpy(buf, &b, sizeof(b));
	break;
	case 2:
	w = cpu_to_le16(readw(base + offset));
	memcpy(buf, &w, sizeof(w));
	break;
	case 4:
	l = cpu_to_le32(readl(base + offset));
	memcpy(buf, &l, sizeof(l));
	break;
	case 8:
	l = cpu_to_le32(readl(base + offset));
	memcpy(buf, &l, sizeof(l));
	l = cpu_to_le32(readl(base + offset + sizeof(l)));
	memcpy(buf + sizeof(l), &l, sizeof(l));
	break;
	default:
	WARN_ON(true);
	}

	return 0;
	}

	static int virtio_mmio_set_config(struct udevice *udev, unsigned int offset,
	const void *buf, unsigned int len)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);
	void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
	u8 b;
	__le16 w;
	__le32 l;

	if (priv->version == 1) {
	const u8 *ptr = buf;
	int i;

	for (i = 0; i < len; i++)
	writeb(ptr[i], base + offset + i);

	return 0;
	}

	switch (len) {
	case 1:
	memcpy(&b, buf, sizeof(b));
	writeb(b, base + offset);
	break;
	case 2:
	memcpy(&w, buf, sizeof(w));
	writew(le16_to_cpu(w), base + offset);
	break;
	case 4:
	memcpy(&l, buf, sizeof(l));
	writel(le32_to_cpu(l), base + offset);
	break;
	case 8:
	memcpy(&l, buf, sizeof(l));
	writel(le32_to_cpu(l), base + offset);
	memcpy(&l, buf + sizeof(l), sizeof(l));
	writel(le32_to_cpu(l), base + offset + sizeof(l));
	break;
	default:
	WARN_ON(true);
	}

	return 0;
	}

	static int virtio_mmio_generation(struct udevice udev, u32 counter)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	if (priv->version == 1)
	*counter = 0;
	else
	*counter = readl(priv->base + VIRTIO_MMIO_CONFIG_GENERATION);

	return 0;
	}

	static int virtio_mmio_get_status(struct udevice udev, u8 status)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	*status = readl(priv->base + VIRTIO_MMIO_STATUS) & 0xff;

	return 0;
	}

	static int virtio_mmio_set_status(struct udevice *udev, u8 status)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	/* We should never be setting status to 0 */
	WARN_ON(status == 0);

	writel(status, priv->base + VIRTIO_MMIO_STATUS);

	return 0;
	}

	static int virtio_mmio_reset(struct udevice *udev)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	/* 0 status means a reset */
	writel(0, priv->base + VIRTIO_MMIO_STATUS);

	return 0;
	}

	static int virtio_mmio_get_features(struct udevice udev, u64 features)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	writel(1, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
	*features = readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);
	*features <<= 32;

	writel(0, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
	*features \|= readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);

	return 0;
	}

	static int virtio_mmio_set_features(struct udevice *udev)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);
	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);

	/* Make sure there is are no mixed devices */
	if (priv->version == 2 && uc_priv->legacy) {
	debug("New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
	return -EINVAL;
	}

	writel(1, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
	writel((u32)(uc_priv->features >> 32),
	priv->base + VIRTIO_MMIO_DRIVER_FEATURES);

	writel(0, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
	writel((u32)uc_priv->features,
	priv->base + VIRTIO_MMIO_DRIVER_FEATURES);

	return 0;
	}

	static struct virtqueue virtio_mmio_setup_vq(struct udevice udev,
	unsigned int index)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);
	struct virtqueue *vq;
	unsigned int num;
	int err;

	/* Select the queue we're interested in */
	writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);

	/* Queue shouldn't already be set up */
	if (readl(priv->base + (priv->version == 1 ?
	VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
	err = -ENOENT;
	goto error_available;
	}

	num = readl(priv->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
	if (num == 0) {
	err = -ENOENT;
	goto error_new_virtqueue;
	}

	/* Create the vring */
	vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, udev);
	if (!vq) {
	err = -ENOMEM;
	goto error_new_virtqueue;
	}

	/* Activate the queue */
	writel(virtqueue_get_vring_size(vq),
	priv->base + VIRTIO_MMIO_QUEUE_NUM);
	if (priv->version == 1) {
	u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;

	/*
	* virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
	* that doesn't fit in 32bit, fail the setup rather than
	* pretending to be successful.
	*/
	if (q_pfn >> 32) {
	debug("platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
	0x1ULL << (32 + PAGE_SHIFT - 30));
	err = -E2BIG;
	goto error_bad_pfn;
	}

	writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_QUEUE_ALIGN);
	writel(q_pfn, priv->base + VIRTIO_MMIO_QUEUE_PFN);
	} else {
	u64 addr;

	addr = virtqueue_get_desc_addr(vq);
	writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
	writel((u32)(addr >> 32),
	priv->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);

	addr = virtqueue_get_avail_addr(vq);
	writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
	writel((u32)(addr >> 32),
	priv->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);

	addr = virtqueue_get_used_addr(vq);
	writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_USED_LOW);
	writel((u32)(addr >> 32),
	priv->base + VIRTIO_MMIO_QUEUE_USED_HIGH);

	writel(1, priv->base + VIRTIO_MMIO_QUEUE_READY);
	}

	return vq;

	error_bad_pfn:
	vring_del_virtqueue(vq);

	error_new_virtqueue:
	if (priv->version == 1) {
	writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
	} else {
	writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
	WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
	}

	error_available:
	return ERR_PTR(err);
	}

	static void virtio_mmio_del_vq(struct virtqueue *vq)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(vq->vdev);
	unsigned int index = vq->index;

	/* Select and deactivate the queue */
	writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);
	if (priv->version == 1) {
	writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
	} else {
	writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
	WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
	}

	vring_del_virtqueue(vq);
	}

	static int virtio_mmio_del_vqs(struct udevice *udev)
	{
	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
	struct virtqueue vq, n;

	list_for_each_entry_safe(vq, n, &uc_priv->vqs, list)
	virtio_mmio_del_vq(vq);

	return 0;
	}

	static int virtio_mmio_find_vqs(struct udevice *udev, unsigned int nvqs,
	struct virtqueue *vqs[])
	{
	int i;

	for (i = 0; i < nvqs; ++i) {
	vqs[i] = virtio_mmio_setup_vq(udev, i);
	if (IS_ERR(vqs[i])) {
	virtio_mmio_del_vqs(udev);
	return PTR_ERR(vqs[i]);
	}
	}

	return 0;
	}

	static int virtio_mmio_notify(struct udevice udev, struct virtqueue vq)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	/*
	* We write the queue's selector into the notification register
	* to signal the other end
	*/
	writel(vq->index, priv->base + VIRTIO_MMIO_QUEUE_NOTIFY);

	return 0;
	}

	static int virtio_mmio_ofdata_to_platdata(struct udevice *udev)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);

	priv->base = (void __iomem *)(ulong)dev_read_addr(udev);
	if (priv->base == (void __iomem *)FDT_ADDR_T_NONE)
	return -EINVAL;

	return 0;
	}

	static int virtio_mmio_probe(struct udevice *udev)
	{
	struct virtio_mmio_priv *priv = dev_get_priv(udev);
	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
	u32 magic;

	/* Check magic value */
	magic = readl(priv->base + VIRTIO_MMIO_MAGIC_VALUE);
	if (magic != ('v' \| 'i' << 8 \| 'r' << 16 \| 't' << 24)) {
	debug("(%s): wrong magic value 0x%08x!\n", udev->name, magic);
	return 0;
	}

	/* Check device version */
	priv->version = readl(priv->base + VIRTIO_MMIO_VERSION);
	if (priv->version < 1 \|\| priv->version > 2) {
	debug("(%s): version %d not supported!\n",
	udev->name, priv->version);
	return 0;
	}

	/* Check device ID */
	uc_priv->device = readl(priv->base + VIRTIO_MMIO_DEVICE_ID);
	if (uc_priv->device == 0) {
	/*
	* virtio-mmio device with an ID 0 is a (dummy) placeholder
	* with no function. End probing now with no error reported.
	*/
	return 0;
	}
	uc_priv->vendor = readl(priv->base + VIRTIO_MMIO_VENDOR_ID);

	if (priv->version == 1)
	writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);

	debug("(%s): device (%d) vendor (%08x) version (%d)\n", udev->name,
	uc_priv->device, uc_priv->vendor, priv->version);

	return 0;
	}

	static const struct dm_virtio_ops virtio_mmio_ops = {
	.get_config = virtio_mmio_get_config,
	.set_config = virtio_mmio_set_config,
	.generation = virtio_mmio_generation,
	.get_status = virtio_mmio_get_status,
	.set_status = virtio_mmio_set_status,
	.reset = virtio_mmio_reset,
	.get_features = virtio_mmio_get_features,
	.set_features = virtio_mmio_set_features,
	.find_vqs = virtio_mmio_find_vqs,
	.del_vqs = virtio_mmio_del_vqs,
	.notify = virtio_mmio_notify,
	};

	static const struct udevice_id virtio_mmio_ids[] = {
	{ .compatible = "virtio,mmio" },
	{ }
	};

	U_BOOT_DRIVER(virtio_mmio) = {
	.name = "virtio-mmio",
	.id = UCLASS_VIRTIO,
	.of_match = virtio_mmio_ids,
	.ops = &virtio_mmio_ops,
	.probe = virtio_mmio_probe,
	.ofdata_to_platdata = virtio_mmio_ofdata_to_platdata,
	.priv_auto_alloc_size = sizeof(struct virtio_mmio_priv),
	};