text: /*
   * Remote processor messaging transport (OMAP platform-specific bits)
   *
   * Copyright (C) 2011 Texas Instruments, Inc.
   * Copyright (C) 2011 Google, Inc.
   *
   * Ohad Ben-Cohen <ohad@wizery.com>
   * Brian Swetland <swetland@google.com>
   *
   * This software is licensed under the terms of the GNU General Public
   * License version 2, as published by the Free Software Foundation, and
   * may be copied, distributed, and modified under those terms.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   */
  
  #include <linux/export.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 void 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);
  }
  
  /**
   * 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 id,
  				    void (*callback)(struct virtqueue *vq),
  				    const char *name)
  {
  	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
  	struct rproc *rproc = vdev_to_rproc(vdev);
  	struct device *dev = &rproc->dev;
  	struct rproc_vring *rvring;
  	struct virtqueue *vq;
  	void *addr;
  	int len, size, ret;
  
  	/* we're temporarily limited to two virtqueues per rvdev */
  	if (id >= ARRAY_SIZE(rvdev->vring))
  		return ERR_PTR(-EINVAL);
  
  	ret = rproc_alloc_vring(rvdev, id);
  	if (ret)
  		return ERR_PTR(ret);
  
  	rvring = &rvdev->vring[id];
  	addr = rvring->va;
  	len = rvring->len;
  
  	/* zero vring */
  	size = vring_size(len, rvring->align);
  	memset(addr, 0, size);
  
  	dev_dbg(dev, "vring%d: va %p 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(len, rvring->align, vdev, false, 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;
  
  	return vq;
  }
  
  static void rproc_virtio_del_vqs(struct virtio_device *vdev)
  {
  	struct virtqueue *vq, *n;
  	struct rproc *rproc = vdev_to_rproc(vdev);
  	struct rproc_vring *rvring;
  
  	/* power down the remote processor before deleting vqs */
  	rproc_shutdown(rproc);
  
  	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {
  		rvring = vq->priv;
  		rvring->vq = NULL;
  		vring_del_virtqueue(vq);
  		rproc_free_vring(rvring);
  	}
  }
  
  static int rproc_virtio_find_vqs(struct virtio_device *vdev, unsigned nvqs,
  		       struct virtqueue *vqs[],
  		       vq_callback_t *callbacks[],
  		       const char *names[])
  {
  	struct rproc *rproc = vdev_to_rproc(vdev);
  	int i, ret;
  
  	for (i = 0; i < nvqs; ++i) {
  		vqs[i] = rp_find_vq(vdev, i, callbacks[i], names[i]);
  		if (IS_ERR(vqs[i])) {
  			ret = PTR_ERR(vqs[i]);
  			goto error;
  		}
  	}
  
  	/* now that the vqs are all set, boot the remote processor */
  	ret = rproc_boot(rproc);
  	if (ret) {
  		dev_err(&rproc->dev, "rproc_boot() failed %d\n", ret);
  		goto error;
  	}
  
  	return 0;
  
  error:
  	rproc_virtio_del_vqs(vdev);
  	return ret;
  }
  
  /*
   * We don't support yet real virtio status semantics.
   *
   * The plan is to provide this via the VDEV resource entry
   * which is part of the firmware: this way the remote processor
   * will be able to access the status values as set by us.
   */
  static u8 rproc_virtio_get_status(struct virtio_device *vdev)
  {
  	return 0;
  }
  
  static void rproc_virtio_set_status(struct virtio_device *vdev, u8 status)
  {
  	dev_dbg(&vdev->dev, "status: %d\n", status);
  }
  
  static void rproc_virtio_reset(struct virtio_device *vdev)
  {
  	dev_dbg(&vdev->dev, "reset !\n");
  }
  
  /* provide the vdev features as retrieved from the firmware */
  static u32 rproc_virtio_get_features(struct virtio_device *vdev)
  {
  	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
  
  	return rvdev->dfeatures;
  }
  
  static void rproc_virtio_finalize_features(struct virtio_device *vdev)
  {
  	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
  
  	/* Give virtio_ring a chance to accept features */
  	vring_transport_features(vdev);
  
  	/*
  	 * Remember the finalized features of our vdev, and provide it
  	 * to the remote processor once it is powered on.
  	 *
  	 * Similarly to the status field, we don't expose yet the negotiated
  	 * features to the remote processors at this point. This will be
  	 * fixed as part of a small resource table overhaul and then an
  	 * extension of the virtio resource entries.
  	 */
  	rvdev->gfeatures = vdev->features[0];
  }
  
  static 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,
  };
  
  /*
   * 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_vdev_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);
  
  	list_del(&rvdev->node);
  	kfree(rvdev);
  
  	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 = &rproc->dev;
  	struct virtio_device *vdev = &rvdev->vdev;
  	int ret;
  
  	vdev->id.device	= id,
  	vdev->config = &rproc_virtio_config_ops,
  	vdev->dev.parent = dev;
  	vdev->dev.release = rproc_vdev_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);
  
  	ret = register_virtio_device(vdev);
  	if (ret) {
  		put_device(&rproc->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
   * @rvdev: the remote vdev
   *
   * This function unregisters an existing virtio device.
   */
  void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
  {
  	unregister_virtio_device(&rvdev->vdev);
  }
  