drivers/remoteproc/remoteproc_virtio.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Remote processor messaging transport (OMAP platform-specific bits)
  *
  * Copyright (C) 2011 Texas Instruments, Inc.
  * Copyright (C) 2011 Google, Inc.
  *
  * Ohad Ben-Cohen <[email protected]>
  * Brian Swetland <[email protected]>
  */

 #include <linux/dma-mapping.h>
 #include <linux/export.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/remoteproc.h>
 #include <linux/virtio.h>
 #include <linux/virtio_config.h>
 #include <linux/virtio_ids.h>
 #include <linux/virtio_ring.h>
 #include <linux/err.h>
 #include <linux/kref.h>
 #include <linux/slab.h>

 #include "remoteproc_internal.h"

 /* kick the remote processor, and let it know which virtqueue to poke at */
 static bool rproc_virtio_notify(struct virtqueue *vq)
 {
 	struct rproc_vring *rvring = vq->priv;
 	struct rproc *rproc = rvring->rvdev->rproc;
 	int notifyid = rvring->notifyid;

 	dev_dbg(&rproc->dev, "kicking vq index: %d\n", notifyid);

 	rproc->ops->kick(rproc, notifyid);
 	return true;
 }

 /**
  * rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
  * @rproc: handle to the remote processor
  * @notifyid: index of the signalled virtqueue (unique per this @rproc)
  *
  * This function should be called by the platform-specific rproc driver,
  * when the remote processor signals that a specific virtqueue has pending
  * messages available.
  *
  * Returns IRQ_NONE if no message was found in the @notifyid virtqueue,
  * and otherwise returns IRQ_HANDLED.
  */
 irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
 {
 	struct rproc_vring *rvring;

 	dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);

 	rvring = idr_find(&rproc->notifyids, notifyid);
 	if (!rvring || !rvring->vq)
 		return IRQ_NONE;

 	return vring_interrupt(0, rvring->vq);
 }
 EXPORT_SYMBOL(rproc_vq_interrupt);

 static struct virtqueue *rp_find_vq(struct virtio_device *vdev,
 				    unsigned int id,
 				    void (*callback)(struct virtqueue *vq),
 				    const char *name, bool ctx)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct rproc *rproc = vdev_to_rproc(vdev);
 	struct device *dev = &rproc->dev;
 	struct rproc_mem_entry *mem;
 	struct rproc_vring *rvring;
 	struct fw_rsc_vdev *rsc;
 	struct virtqueue *vq;
 	void *addr;
 	int len, size;

 	/* we're temporarily limited to two virtqueues per rvdev */
 	if (id >= ARRAY_SIZE(rvdev->vring))
 		return ERR_PTR(-EINVAL);

 	if (!name)
 		return NULL;

 	/* Search allocated memory region by name */
 	mem = rproc_find_carveout_by_name(rproc, "vdev%dvring%d", rvdev->index,
 					  id);
 	if (!mem || !mem->va)
 		return ERR_PTR(-ENOMEM);

 	rvring = &rvdev->vring[id];
 	addr = mem->va;
 	len = rvring->len;

 	/* zero vring */
 	size = vring_size(len, rvring->align);
 	memset(addr, 0, size);

 	dev_dbg(dev, "vring%d: va %pK qsz %d notifyid %d\n",
 		id, addr, len, rvring->notifyid);

 	/*
 	 * Create the new vq, and tell virtio we're not interested in
 	 * the 'weak' smp barriers, since we're talking with a real device.
 	 */
 	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, ctx,
 				 addr, rproc_virtio_notify, callback, name);
 	if (!vq) {
 		dev_err(dev, "vring_new_virtqueue %s failed\n", name);
 		rproc_free_vring(rvring);
 		return ERR_PTR(-ENOMEM);
 	}

 	rvring->vq = vq;
 	vq->priv = rvring;

 	/* Update vring in resource table */
 	rsc = (void *)rproc->table_ptr + rvdev->rsc_offset;
 	rsc->vring[id].da = mem->da;

 	return vq;
 }

 static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
 {
 	struct virtqueue *vq, *n;
 	struct rproc_vring *rvring;

 	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
 		rvring = vq->priv;
 		rvring->vq = NULL;
 		vring_del_virtqueue(vq);
 	}
 }

 static void rproc_virtio_del_vqs(struct virtio_device *vdev)
 {
 	__rproc_virtio_del_vqs(vdev);
 }

 static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
 				 struct virtqueue *vqs[],
 				 vq_callback_t *callbacks[],
 				 const char * const names[],
 				 const bool * ctx,
 				 struct irq_affinity *desc)
 {
 	int i, ret, queue_idx = 0;

 	for (i = 0; i < nvqs; ++i) {
 		if (!names[i]) {
 			vqs[i] = NULL;
 			continue;
 		}

 		vqs[i] = rp_find_vq(vdev, queue_idx++, callbacks[i], names[i],
 				    ctx ? ctx[i] : false);
 		if (IS_ERR(vqs[i])) {
 			ret = PTR_ERR(vqs[i]);
 			goto error;
 		}
 	}

 	return 0;

 error:
 	__rproc_virtio_del_vqs(vdev);
 	return ret;
 }

 static u8 rproc_virtio_get_status(struct virtio_device *vdev)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

 	return rsc->status;
 }

 static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

 	rsc->status = status;
 	dev_dbg(&vdev->dev, "status: %d\n", status);
 }

 static void rproc_virtio_reset(struct virtio_device *vdev)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

 	rsc->status = 0;
 	dev_dbg(&vdev->dev, "reset !\n");
 }

 /* provide the vdev features as retrieved from the firmware */
 static u64 rproc_virtio_get_features(struct virtio_device *vdev)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

 	return rsc->dfeatures;
 }

 static void rproc_transport_features(struct virtio_device *vdev)
 {
 	/*
 	 * Packed ring isn't enabled on remoteproc for now,
 	 * because remoteproc uses vring_new_virtqueue() which
 	 * creates virtio rings on preallocated memory.
 	 */
 	__virtio_clear_bit(vdev, VIRTIO_F_RING_PACKED);
 }

 static int rproc_virtio_finalize_features(struct virtio_device *vdev)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

 	/* Give virtio_ring a chance to accept features */
 	vring_transport_features(vdev);

 	/* Give virtio_rproc a chance to accept features. */
 	rproc_transport_features(vdev);

 	/* Make sure we don't have any features > 32 bits! */
 	BUG_ON((u32)vdev->features != vdev->features);

 	/*
 	 * Remember the finalized features of our vdev, and provide it
 	 * to the remote processor once it is powered on.
 	 */
 	rsc->gfeatures = vdev->features;

 	return 0;
 }

 static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset,
 			     void *buf, unsigned int len)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;
 	void *cfg;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
 	cfg = &rsc->vring[rsc->num_of_vrings];

 	if (offset + len > rsc->config_len || offset + len < len) {
 		dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
 		return;
 	}

 	memcpy(buf, cfg + offset, len);
 }

 static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset,
 			     const void *buf, unsigned int len)
 {
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct fw_rsc_vdev *rsc;
 	void *cfg;

 	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
 	cfg = &rsc->vring[rsc->num_of_vrings];

 	if (offset + len > rsc->config_len || offset + len < len) {
 		dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
 		return;
 	}

 	memcpy(cfg + offset, buf, len);
 }

 static const struct virtio_config_ops rproc_virtio_config_ops = {
 	.get_features	= rproc_virtio_get_features,
 	.finalize_features = rproc_virtio_finalize_features,
 	.find_vqs	= rproc_virtio_find_vqs,
 	.del_vqs	= rproc_virtio_del_vqs,
 	.reset		= rproc_virtio_reset,
 	.set_status	= rproc_virtio_set_status,
 	.get_status	= rproc_virtio_get_status,
 	.get		= rproc_virtio_get,
 	.set		= rproc_virtio_set,
 };

 /*
  * This function is called whenever vdev is released, and is responsible
  * to decrement the remote processor's refcount which was taken when vdev was
  * added.
  *
  * Never call this function directly; it will be called by the driver
  * core when needed.
  */
 static void rproc_virtio_dev_release(struct device *dev)
 {
 	struct virtio_device *vdev = dev_to_virtio(dev);
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct rproc *rproc = vdev_to_rproc(vdev);

 	kfree(vdev);

 	kref_put(&rvdev->refcount, rproc_vdev_release);

 	put_device(&rproc->dev);
 }

 /**
  * rproc_add_virtio_dev() - register an rproc-induced virtio device
  * @rvdev: the remote vdev
  *
  * This function registers a virtio device. This vdev's partent is
  * the rproc device.
  *
  * Returns 0 on success or an appropriate error value otherwise.
  */
 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
 {
 	struct rproc *rproc = rvdev->rproc;
 	struct device *dev = &rvdev->dev;
 	struct virtio_device *vdev;
 	struct rproc_mem_entry *mem;
 	int ret;

 	/* Try to find dedicated vdev buffer carveout */
 	mem = rproc_find_carveout_by_name(rproc, "vdev%dbuffer", rvdev->index);
 	if (mem) {
 		phys_addr_t pa;

 		if (mem->of_resm_idx != -1) {
 			struct device_node *np = rproc->dev.parent->of_node;

 			/* Associate reserved memory to vdev device */
 			ret = of_reserved_mem_device_init_by_idx(dev, np,
 								 mem->of_resm_idx);
 			if (ret) {
 				dev_err(dev, "Can't associate reserved memory\n");
 				goto out;
 			}
 		} else {
 			if (mem->va) {
 				dev_warn(dev, "vdev %d buffer already mapped\n",
 					 rvdev->index);
 				pa = rproc_va_to_pa(mem->va);
 			} else {
 				/* Use dma address as carveout no memmapped yet */
 				pa = (phys_addr_t)mem->dma;
 			}

 			/* Associate vdev buffer memory pool to vdev subdev */
 			ret = dma_declare_coherent_memory(dev, pa,
 							   mem->da,
 							   mem->len);
 			if (ret < 0) {
 				dev_err(dev, "Failed to associate buffer\n");
 				goto out;
 			}
 		}
 	}

 	/* Allocate virtio device */
 	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
 	if (!vdev) {
 		ret = -ENOMEM;
 		goto out;
 	}
 	vdev->id.device	= id,
 	vdev->config = &rproc_virtio_config_ops,
 	vdev->dev.parent = dev;
 	vdev->dev.release = rproc_virtio_dev_release;

 	/*
 	 * We're indirectly making a non-temporary copy of the rproc pointer
 	 * here, because drivers probed with this vdev will indirectly
 	 * access the wrapping rproc.
 	 *
 	 * Therefore we must increment the rproc refcount here, and decrement
 	 * it _only_ when the vdev is released.
 	 */
 	get_device(&rproc->dev);

 	/* Reference the vdev and vring allocations */
 	kref_get(&rvdev->refcount);

 	ret = register_virtio_device(vdev);
 	if (ret) {
 		put_device(&vdev->dev);
 		dev_err(dev, "failed to register vdev: %d\n", ret);
 		goto out;
 	}

 	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);

 out:
 	return ret;
 }

 /**
  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
  * @dev: the virtio device
  * @data: must be null
  *
  * This function unregisters an existing virtio device.
  */
 int rproc_remove_virtio_dev(struct device *dev, void *data)
 {
 	struct virtio_device *vdev = dev_to_virtio(dev);

 	unregister_virtio_device(vdev);
 	return 0;
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Remote processor messaging transport (OMAP platform-specific bits)
	*
	* Copyright (C) 2011 Texas Instruments, Inc.
	* Copyright (C) 2011 Google, Inc.
	*
	* Ohad Ben-Cohen <[email protected]>
	* Brian Swetland <[email protected]>
	*/

	#include <linux/dma-mapping.h>
	#include <linux/export.h>
	#include <linux/of_reserved_mem.h>
	#include <linux/remoteproc.h>
	#include <linux/virtio.h>
	#include <linux/virtio_config.h>
	#include <linux/virtio_ids.h>
	#include <linux/virtio_ring.h>
	#include <linux/err.h>
	#include <linux/kref.h>
	#include <linux/slab.h>

	#include "remoteproc_internal.h"

	/* kick the remote processor, and let it know which virtqueue to poke at */
	static bool rproc_virtio_notify(struct virtqueue *vq)
	{
	struct rproc_vring *rvring = vq->priv;
	struct rproc *rproc = rvring->rvdev->rproc;
	int notifyid = rvring->notifyid;

	dev_dbg(&rproc->dev, "kicking vq index: %d\n", notifyid);

	rproc->ops->kick(rproc, notifyid);
	return true;
	}

	/**
	* rproc_vq_interrupt() - tell remoteproc that a virtqueue is interrupted
	* @rproc: handle to the remote processor
	* @notifyid: index of the signalled virtqueue (unique per this @rproc)
	*
	* This function should be called by the platform-specific rproc driver,
	* when the remote processor signals that a specific virtqueue has pending
	* messages available.
	*
	* Returns IRQ_NONE if no message was found in the @notifyid virtqueue,
	* and otherwise returns IRQ_HANDLED.
	*/
	irqreturn_t rproc_vq_interrupt(struct rproc *rproc, int notifyid)
	{
	struct rproc_vring *rvring;

	dev_dbg(&rproc->dev, "vq index %d is interrupted\n", notifyid);

	rvring = idr_find(&rproc->notifyids, notifyid);
	if (!rvring \|\| !rvring->vq)
	return IRQ_NONE;

	return vring_interrupt(0, rvring->vq);
	}
	EXPORT_SYMBOL(rproc_vq_interrupt);

	static struct virtqueue rp_find_vq(struct virtio_device vdev,
	unsigned int id,
	void (callback)(struct virtqueue vq),
	const char *name, bool ctx)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct rproc *rproc = vdev_to_rproc(vdev);
	struct device *dev = &rproc->dev;
	struct rproc_mem_entry *mem;
	struct rproc_vring *rvring;
	struct fw_rsc_vdev *rsc;
	struct virtqueue *vq;
	void *addr;
	int len, size;

	/* we're temporarily limited to two virtqueues per rvdev */
	if (id >= ARRAY_SIZE(rvdev->vring))
	return ERR_PTR(-EINVAL);

	if (!name)
	return NULL;

	/* Search allocated memory region by name */
	mem = rproc_find_carveout_by_name(rproc, "vdev%dvring%d", rvdev->index,
	id);
	if (!mem \|\| !mem->va)
	return ERR_PTR(-ENOMEM);

	rvring = &rvdev->vring[id];
	addr = mem->va;
	len = rvring->len;

	/* zero vring */
	size = vring_size(len, rvring->align);
	memset(addr, 0, size);

	dev_dbg(dev, "vring%d: va %pK qsz %d notifyid %d\n",
	id, addr, len, rvring->notifyid);

	/*
	* Create the new vq, and tell virtio we're not interested in
	* the 'weak' smp barriers, since we're talking with a real device.
	*/
	vq = vring_new_virtqueue(id, len, rvring->align, vdev, false, ctx,
	addr, rproc_virtio_notify, callback, name);
	if (!vq) {
	dev_err(dev, "vring_new_virtqueue %s failed\n", name);
	rproc_free_vring(rvring);
	return ERR_PTR(-ENOMEM);
	}

	rvring->vq = vq;
	vq->priv = rvring;

	/* Update vring in resource table */
	rsc = (void *)rproc->table_ptr + rvdev->rsc_offset;
	rsc->vring[id].da = mem->da;

	return vq;
	}

	static void __rproc_virtio_del_vqs(struct virtio_device *vdev)
	{
	struct virtqueue vq, n;
	struct rproc_vring *rvring;

	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
	rvring = vq->priv;
	rvring->vq = NULL;
	vring_del_virtqueue(vq);
	}
	}

	static void rproc_virtio_del_vqs(struct virtio_device *vdev)
	{
	__rproc_virtio_del_vqs(vdev);
	}

	static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
	struct virtqueue *vqs[],
	vq_callback_t *callbacks[],
	const char * const names[],
	const bool * ctx,
	struct irq_affinity *desc)
	{
	int i, ret, queue_idx = 0;

	for (i = 0; i < nvqs; ++i) {
	if (!names[i]) {
	vqs[i] = NULL;
	continue;
	}

	vqs[i] = rp_find_vq(vdev, queue_idx++, callbacks[i], names[i],
	ctx ? ctx[i] : false);
	if (IS_ERR(vqs[i])) {
	ret = PTR_ERR(vqs[i]);
	goto error;
	}
	}

	return 0;

	error:
	__rproc_virtio_del_vqs(vdev);
	return ret;
	}

	static u8 rproc_virtio_get_status(struct virtio_device *vdev)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

	return rsc->status;
	}

	static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

	rsc->status = status;
	dev_dbg(&vdev->dev, "status: %d\n", status);
	}

	static void rproc_virtio_reset(struct virtio_device *vdev)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

	rsc->status = 0;
	dev_dbg(&vdev->dev, "reset !\n");
	}

	/* provide the vdev features as retrieved from the firmware */
	static u64 rproc_virtio_get_features(struct virtio_device *vdev)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

	return rsc->dfeatures;
	}

	static void rproc_transport_features(struct virtio_device *vdev)
	{
	/*
	* Packed ring isn't enabled on remoteproc for now,
	* because remoteproc uses vring_new_virtqueue() which
	* creates virtio rings on preallocated memory.
	*/
	__virtio_clear_bit(vdev, VIRTIO_F_RING_PACKED);
	}

	static int rproc_virtio_finalize_features(struct virtio_device *vdev)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;

	/* Give virtio_ring a chance to accept features */
	vring_transport_features(vdev);

	/* Give virtio_rproc a chance to accept features. */
	rproc_transport_features(vdev);

	/* Make sure we don't have any features > 32 bits! */
	BUG_ON((u32)vdev->features != vdev->features);

	/*
	* Remember the finalized features of our vdev, and provide it
	* to the remote processor once it is powered on.
	*/
	rsc->gfeatures = vdev->features;

	return 0;
	}

	static void rproc_virtio_get(struct virtio_device *vdev, unsigned int offset,
	void *buf, unsigned int len)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;
	void *cfg;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
	cfg = &rsc->vring[rsc->num_of_vrings];

	if (offset + len > rsc->config_len \|\| offset + len < len) {
	dev_err(&vdev->dev, "rproc_virtio_get: access out of bounds\n");
	return;
	}

	memcpy(buf, cfg + offset, len);
	}

	static void rproc_virtio_set(struct virtio_device *vdev, unsigned int offset,
	const void *buf, unsigned int len)
	{
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct fw_rsc_vdev *rsc;
	void *cfg;

	rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset;
	cfg = &rsc->vring[rsc->num_of_vrings];

	if (offset + len > rsc->config_len \|\| offset + len < len) {
	dev_err(&vdev->dev, "rproc_virtio_set: access out of bounds\n");
	return;
	}

	memcpy(cfg + offset, buf, len);
	}

	static const struct virtio_config_ops rproc_virtio_config_ops = {
	.get_features = rproc_virtio_get_features,
	.finalize_features = rproc_virtio_finalize_features,
	.find_vqs = rproc_virtio_find_vqs,
	.del_vqs = rproc_virtio_del_vqs,
	.reset = rproc_virtio_reset,
	.set_status = rproc_virtio_set_status,
	.get_status = rproc_virtio_get_status,
	.get = rproc_virtio_get,
	.set = rproc_virtio_set,
	};

	/*
	* This function is called whenever vdev is released, and is responsible
	* to decrement the remote processor's refcount which was taken when vdev was
	* added.
	*
	* Never call this function directly; it will be called by the driver
	* core when needed.
	*/
	static void rproc_virtio_dev_release(struct device *dev)
	{
	struct virtio_device *vdev = dev_to_virtio(dev);
	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
	struct rproc *rproc = vdev_to_rproc(vdev);

	kfree(vdev);

	kref_put(&rvdev->refcount, rproc_vdev_release);

	put_device(&rproc->dev);
	}

	/**
	* rproc_add_virtio_dev() - register an rproc-induced virtio device
	* @rvdev: the remote vdev
	*
	* This function registers a virtio device. This vdev's partent is
	* the rproc device.
	*
	* Returns 0 on success or an appropriate error value otherwise.
	*/
	int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
	{
	struct rproc *rproc = rvdev->rproc;
	struct device *dev = &rvdev->dev;
	struct virtio_device *vdev;
	struct rproc_mem_entry *mem;
	int ret;

	/* Try to find dedicated vdev buffer carveout */
	mem = rproc_find_carveout_by_name(rproc, "vdev%dbuffer", rvdev->index);
	if (mem) {
	phys_addr_t pa;

	if (mem->of_resm_idx != -1) {
	struct device_node *np = rproc->dev.parent->of_node;

	/* Associate reserved memory to vdev device */
	ret = of_reserved_mem_device_init_by_idx(dev, np,
	mem->of_resm_idx);
	if (ret) {
	dev_err(dev, "Can't associate reserved memory\n");
	goto out;
	}
	} else {
	if (mem->va) {
	dev_warn(dev, "vdev %d buffer already mapped\n",
	rvdev->index);
	pa = rproc_va_to_pa(mem->va);
	} else {
	/* Use dma address as carveout no memmapped yet */
	pa = (phys_addr_t)mem->dma;
	}

	/* Associate vdev buffer memory pool to vdev subdev */
	ret = dma_declare_coherent_memory(dev, pa,
	mem->da,
	mem->len);
	if (ret < 0) {
	dev_err(dev, "Failed to associate buffer\n");
	goto out;
	}
	}
	}

	/* Allocate virtio device */
	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
	if (!vdev) {
	ret = -ENOMEM;
	goto out;
	}
	vdev->id.device = id,
	vdev->config = &rproc_virtio_config_ops,
	vdev->dev.parent = dev;
	vdev->dev.release = rproc_virtio_dev_release;

	/*
	* We're indirectly making a non-temporary copy of the rproc pointer
	* here, because drivers probed with this vdev will indirectly
	* access the wrapping rproc.
	*
	* Therefore we must increment the rproc refcount here, and decrement
	* it _only_ when the vdev is released.
	*/
	get_device(&rproc->dev);

	/* Reference the vdev and vring allocations */
	kref_get(&rvdev->refcount);

	ret = register_virtio_device(vdev);
	if (ret) {
	put_device(&vdev->dev);
	dev_err(dev, "failed to register vdev: %d\n", ret);
	goto out;
	}

	dev_info(dev, "registered %s (type %d)\n", dev_name(&vdev->dev), id);

	out:
	return ret;
	}

	/**
	* rproc_remove_virtio_dev() - remove an rproc-induced virtio device
	* @dev: the virtio device
	* @data: must be null
	*
	* This function unregisters an existing virtio device.
	*/
	int rproc_remove_virtio_dev(struct device dev, void data)
	{
	struct virtio_device *vdev = dev_to_virtio(dev);

	unregister_virtio_device(vdev);
	return 0;
	}