/*

   * Virtio PCI driver - common functionality for all device versions

   *
   * This module allows virtio devices to be used over a virtual PCI device.
   * This can be used with QEMU based VMMs like KVM or Xen.
   *
   * Copyright IBM Corp. 2007

   * Copyright Red Hat, Inc. 2014

   *
   * Authors:
   *  Anthony Liguori  <aliguori@us.ibm.com>

   *  Rusty Russell <rusty@rustcorp.com.au>
   *  Michael S. Tsirkin <mst@redhat.com>

   *
   * This work is licensed under the terms of the GNU GPL, version 2 or later.
   * See the COPYING file in the top-level directory.
   *
   */

  #include "virtio_pci_common.h"

  static bool force_legacy = false;
  
  #if IS_ENABLED(CONFIG_VIRTIO_PCI_LEGACY)
  module_param(force_legacy, bool, 0444);
  MODULE_PARM_DESC(force_legacy,
  		 "Force legacy mode for transitional virtio 1 devices");
  #endif

  /* wait for pending irq handlers */

  void vp_synchronize_vectors(struct virtio_device *vdev)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	int i;

  	if (vp_dev->intx_enabled)
  		synchronize_irq(vp_dev->pci_dev->irq);
  
  	for (i = 0; i < vp_dev->msix_vectors; ++i)

  		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));

  }

  /* the notify function used when creating a virt queue */

  bool vp_notify(struct virtqueue *vq)

  {

  	/* we write the queue's selector into the notification register to
  	 * signal the other end */

  	iowrite16(vq->index, (void __iomem *)vq->priv);

  	return true;

  }

  /* Handle a configuration change: Tell driver if it wants to know. */
  static irqreturn_t vp_config_changed(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;

  	virtio_config_changed(&vp_dev->vdev);

  	return IRQ_HANDLED;
  }
  
  /* Notify all virtqueues on an interrupt. */
  static irqreturn_t vp_vring_interrupt(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;

  	struct virtio_pci_vq_info *info;

  	irqreturn_t ret = IRQ_NONE;

  	unsigned long flags;

  	spin_lock_irqsave(&vp_dev->lock, flags);
  	list_for_each_entry(info, &vp_dev->virtqueues, node) {
  		if (vring_interrupt(irq, info->vq) == IRQ_HANDLED)

  			ret = IRQ_HANDLED;
  	}

  	spin_unlock_irqrestore(&vp_dev->lock, flags);

  
  	return ret;
  }

  /* A small wrapper to also acknowledge the interrupt when it's handled.
   * I really need an EIO hook for the vring so I can ack the interrupt once we
   * know that we'll be handling the IRQ but before we invoke the callback since
   * the callback may notify the host which results in the host attempting to
   * raise an interrupt that we would then mask once we acknowledged the
   * interrupt. */
  static irqreturn_t vp_interrupt(int irq, void *opaque)
  {
  	struct virtio_pci_device *vp_dev = opaque;

  	u8 isr;
  
  	/* reading the ISR has the effect of also clearing it so it's very
  	 * important to save off the value. */

  	isr = ioread8(vp_dev->isr);

  
  	/* It's definitely not us if the ISR was not high */
  	if (!isr)
  		return IRQ_NONE;
  
  	/* Configuration change?  Tell driver if it wants to know. */

  	if (isr & VIRTIO_PCI_ISR_CONFIG)
  		vp_config_changed(irq, opaque);

  	return vp_vring_interrupt(irq, opaque);

  }

  static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
  				   bool per_vq_vectors, struct irq_affinity *desc)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	const char *name = dev_name(&vp_dev->vdev.dev);

  	unsigned flags = PCI_IRQ_MSIX;

  	unsigned i, v;
  	int err = -ENOMEM;
  
  	vp_dev->msix_vectors = nvectors;
  
  	vp_dev->msix_names = kmalloc(nvectors * sizeof *vp_dev->msix_names,
  				     GFP_KERNEL);
  	if (!vp_dev->msix_names)
  		goto error;
  	vp_dev->msix_affinity_masks
  		= kzalloc(nvectors * sizeof *vp_dev->msix_affinity_masks,
  			  GFP_KERNEL);
  	if (!vp_dev->msix_affinity_masks)
  		goto error;
  	for (i = 0; i < nvectors; ++i)
  		if (!alloc_cpumask_var(&vp_dev->msix_affinity_masks[i],
  					GFP_KERNEL))
  			goto error;

  	if (desc) {
  		flags |= PCI_IRQ_AFFINITY;
  		desc->pre_vectors++; /* virtio config vector */
  	}

  	err = pci_alloc_irq_vectors_affinity(vp_dev->pci_dev, nvectors,

  					     nvectors, flags, desc);

  	if (err < 0)
  		goto error;
  	vp_dev->msix_enabled = 1;
  
  	/* Set the vector used for configuration */
  	v = vp_dev->msix_used_vectors;
  	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
  		 "%s-config", name);
  	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
  			  vp_config_changed, 0, vp_dev->msix_names[v],
  			  vp_dev);
  	if (err)
  		goto error;
  	++vp_dev->msix_used_vectors;
  
  	v = vp_dev->config_vector(vp_dev, v);
  	/* Verify we had enough resources to assign the vector */
  	if (v == VIRTIO_MSI_NO_VECTOR) {
  		err = -EBUSY;
  		goto error;
  	}
  
  	if (!per_vq_vectors) {
  		/* Shared vector for all VQs */
  		v = vp_dev->msix_used_vectors;
  		snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
  			 "%s-virtqueues", name);
  		err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
  				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
  				  vp_dev);
  		if (err)
  			goto error;
  		++vp_dev->msix_used_vectors;
  	}
  	return 0;
  error:
  	return err;
  }

  static struct virtqueue *vp_setup_vq(struct virtio_device *vdev, unsigned index,
  				     void (*callback)(struct virtqueue *vq),
  				     const char *name,

  				     bool ctx,

  				     u16 msix_vec)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	struct virtio_pci_vq_info *info = kmalloc(sizeof *info, GFP_KERNEL);
  	struct virtqueue *vq;
  	unsigned long flags;
  
  	/* fill out our structure that represents an active queue */
  	if (!info)
  		return ERR_PTR(-ENOMEM);

  	vq = vp_dev->setup_vq(vp_dev, info, index, callback, name, ctx,

  			      msix_vec);
  	if (IS_ERR(vq))
  		goto out_info;
  
  	info->vq = vq;
  	if (callback) {
  		spin_lock_irqsave(&vp_dev->lock, flags);
  		list_add(&info->node, &vp_dev->virtqueues);
  		spin_unlock_irqrestore(&vp_dev->lock, flags);
  	} else {
  		INIT_LIST_HEAD(&info->node);
  	}
  
  	vp_dev->vqs[index] = info;
  	return vq;
  
  out_info:
  	kfree(info);
  	return vq;
  }
  
  static void vp_del_vq(struct virtqueue *vq)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
  	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
  	unsigned long flags;
  
  	spin_lock_irqsave(&vp_dev->lock, flags);
  	list_del(&info->node);
  	spin_unlock_irqrestore(&vp_dev->lock, flags);
  
  	vp_dev->del_vq(info);
  	kfree(info);
  }

  /* the config->del_vqs() implementation */
  void vp_del_vqs(struct virtio_device *vdev)

  {

  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	struct virtqueue *vq, *n;

  	int i;

  	list_for_each_entry_safe(vq, n, &vdev->vqs, list) {

  		if (vp_dev->per_vq_vectors) {
  			int v = vp_dev->vqs[vq->index]->msix_vector;

  			if (v != VIRTIO_MSI_NO_VECTOR) {
  				int irq = pci_irq_vector(vp_dev->pci_dev, v);
  
  				irq_set_affinity_hint(irq, NULL);
  				free_irq(irq, vq);
  			}

  		}

  		vp_del_vq(vq);

  	}

  	vp_dev->per_vq_vectors = false;

  	if (vp_dev->intx_enabled) {
  		free_irq(vp_dev->pci_dev->irq, vp_dev);
  		vp_dev->intx_enabled = 0;
  	}

  	for (i = 0; i < vp_dev->msix_used_vectors; ++i)
  		free_irq(pci_irq_vector(vp_dev->pci_dev, i), vp_dev);

  	for (i = 0; i < vp_dev->msix_vectors; i++)
  		if (vp_dev->msix_affinity_masks[i])

  			free_cpumask_var(vp_dev->msix_affinity_masks[i]);

  	if (vp_dev->msix_enabled) {

  		/* Disable the vector used for configuration */
  		vp_dev->config_vector(vp_dev, VIRTIO_MSI_NO_VECTOR);

  		pci_free_irq_vectors(vp_dev->pci_dev);
  		vp_dev->msix_enabled = 0;

  	}

  	vp_dev->msix_vectors = 0;
  	vp_dev->msix_used_vectors = 0;
  	kfree(vp_dev->msix_names);
  	vp_dev->msix_names = NULL;
  	kfree(vp_dev->msix_affinity_masks);
  	vp_dev->msix_affinity_masks = NULL;

  	kfree(vp_dev->vqs);
  	vp_dev->vqs = NULL;

  }

  static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,

  		struct virtqueue *vqs[], vq_callback_t *callbacks[],

  		const char * const names[], bool per_vq_vectors,

  		const bool *ctx,

  		struct irq_affinity *desc)

  {

  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	u16 msix_vec;

  	int i, err, nvectors, allocated_vectors;

  	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
  	if (!vp_dev->vqs)
  		return -ENOMEM;

  	if (per_vq_vectors) {

  		/* Best option: one for change interrupt, one per vq. */
  		nvectors = 1;
  		for (i = 0; i < nvqs; ++i)
  			if (callbacks[i])
  				++nvectors;

  	} else {

  		/* Second best: one for change, shared for all vqs. */
  		nvectors = 2;

  	}

  	err = vp_request_msix_vectors(vdev, nvectors, per_vq_vectors,
  				      per_vq_vectors ? desc : NULL);

  	if (err)

  		goto error_find;

  	vp_dev->per_vq_vectors = per_vq_vectors;

  	allocated_vectors = vp_dev->msix_used_vectors;

  	for (i = 0; i < nvqs; ++i) {

  		if (!names[i]) {
  			vqs[i] = NULL;
  			continue;

  		}

  		if (!callbacks[i])

  			msix_vec = VIRTIO_MSI_NO_VECTOR;

  		else if (vp_dev->per_vq_vectors)

  			msix_vec = allocated_vectors++;
  		else
  			msix_vec = VP_MSIX_VQ_VECTOR;

  		vqs[i] = vp_setup_vq(vdev, i, callbacks[i], names[i],

  				     ctx ? ctx[i] : false,

  				     msix_vec);

  		if (IS_ERR(vqs[i])) {
  			err = PTR_ERR(vqs[i]);

  			goto error_find;

  		}

  		if (!vp_dev->per_vq_vectors || msix_vec == VIRTIO_MSI_NO_VECTOR)

  			continue;

  		/* allocate per-vq irq if available and necessary */
  		snprintf(vp_dev->msix_names[msix_vec],
  			 sizeof *vp_dev->msix_names,
  			 "%s-%s",

  			 dev_name(&vp_dev->vdev.dev), names[i]);

  		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),

  				  vring_interrupt, 0,
  				  vp_dev->msix_names[msix_vec],
  				  vqs[i]);

  		if (err)

  			goto error_find;

  	}
  	return 0;

  error_find:
  	vp_del_vqs(vdev);

  	return err;
  }

  static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned nvqs,
  		struct virtqueue *vqs[], vq_callback_t *callbacks[],

  		const char * const names[], const bool *ctx)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  	int i, err;

  	vp_dev->vqs = kcalloc(nvqs, sizeof(*vp_dev->vqs), GFP_KERNEL);
  	if (!vp_dev->vqs)
  		return -ENOMEM;

  	err = request_irq(vp_dev->pci_dev->irq, vp_interrupt, IRQF_SHARED,
  			dev_name(&vdev->dev), vp_dev);
  	if (err)

  		goto out_del_vqs;

  	vp_dev->intx_enabled = 1;

  	vp_dev->per_vq_vectors = false;

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

  		vqs[i] = vp_setup_vq(vdev, i, callbacks[i], names[i],

  				     ctx ? ctx[i] : false,

  				     VIRTIO_MSI_NO_VECTOR);

  		if (IS_ERR(vqs[i])) {
  			err = PTR_ERR(vqs[i]);

  			goto out_del_vqs;

  		}
  	}
  
  	return 0;

  out_del_vqs:
  	vp_del_vqs(vdev);

  	return err;
  }

  /* the config->find_vqs() implementation */

  int vp_find_vqs(struct virtio_device *vdev, unsigned nvqs,

  		struct virtqueue *vqs[], vq_callback_t *callbacks[],

  		const char * const names[], const bool *ctx,
  		struct irq_affinity *desc)

  {

  	int err;

  	/* Try MSI-X with one vector per queue. */

  	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, true, ctx, desc);

  	if (!err)
  		return 0;
  	/* Fallback: MSI-X with one vector for config, one shared for queues. */

  	err = vp_find_vqs_msix(vdev, nvqs, vqs, callbacks, names, false, ctx, desc);

  	if (!err)
  		return 0;

  	/* Finally fall back to regular interrupts. */

  	return vp_find_vqs_intx(vdev, nvqs, vqs, callbacks, names, ctx);

  }

  const char *vp_bus_name(struct virtio_device *vdev)

  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  
  	return pci_name(vp_dev->pci_dev);
  }

  /* Setup the affinity for a virtqueue:
   * - force the affinity for per vq vector
   * - OR over all affinities for shared MSI
   * - ignore the affinity request if we're using INTX
   */

  int vp_set_vq_affinity(struct virtqueue *vq, int cpu)

  {
  	struct virtio_device *vdev = vq->vdev;
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	struct virtio_pci_vq_info *info = vp_dev->vqs[vq->index];
  	struct cpumask *mask;
  	unsigned int irq;

  
  	if (!vq->callback)
  		return -EINVAL;

  	if (vp_dev->msix_enabled) {

  		mask = vp_dev->msix_affinity_masks[info->msix_vector];
  		irq = pci_irq_vector(vp_dev->pci_dev, info->msix_vector);

  		if (cpu == -1)
  			irq_set_affinity_hint(irq, NULL);
  		else {

  			cpumask_clear(mask);

  			cpumask_set_cpu(cpu, mask);
  			irq_set_affinity_hint(irq, mask);
  		}
  	}
  	return 0;
  }

  const struct cpumask *vp_get_vq_affinity(struct virtio_device *vdev, int index)
  {
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);

  	if (!vp_dev->per_vq_vectors ||
  	    vp_dev->vqs[index]->msix_vector == VIRTIO_MSI_NO_VECTOR)

  		return NULL;

  	return pci_irq_get_affinity(vp_dev->pci_dev,
  				    vp_dev->vqs[index]->msix_vector);

  }

  #ifdef CONFIG_PM_SLEEP

  static int virtio_pci_freeze(struct device *dev)
  {
  	struct pci_dev *pci_dev = to_pci_dev(dev);
  	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);

  	int ret;

  	ret = virtio_device_freeze(&vp_dev->vdev);

  
  	if (!ret)
  		pci_disable_device(pci_dev);
  	return ret;
  }

  static int virtio_pci_restore(struct device *dev)

  {
  	struct pci_dev *pci_dev = to_pci_dev(dev);
  	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
  	int ret;
  
  	ret = pci_enable_device(pci_dev);
  	if (ret)
  		return ret;

  	pci_set_master(pci_dev);

  	return virtio_device_restore(&vp_dev->vdev);

  }

  static const struct dev_pm_ops virtio_pci_pm_ops = {

  	SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)

  };

  #endif

  
  
  /* Qumranet donated their vendor ID for devices 0x1000 thru 0x10FF. */
  static const struct pci_device_id virtio_pci_id_table[] = {

  	{ PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) },

  	{ 0 }
  };
  
  MODULE_DEVICE_TABLE(pci, virtio_pci_id_table);

  static void virtio_pci_release_dev(struct device *_d)
  {
  	struct virtio_device *vdev = dev_to_virtio(_d);
  	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
  
  	/* As struct device is a kobject, it's not safe to
  	 * free the memory (including the reference counter itself)
  	 * until it's release callback. */
  	kfree(vp_dev);
  }

  static int virtio_pci_probe(struct pci_dev *pci_dev,
  			    const struct pci_device_id *id)
  {

  	struct virtio_pci_device *vp_dev;
  	int rc;
  
  	/* allocate our structure and fill it out */
  	vp_dev = kzalloc(sizeof(struct virtio_pci_device), GFP_KERNEL);
  	if (!vp_dev)
  		return -ENOMEM;
  
  	pci_set_drvdata(pci_dev, vp_dev);
  	vp_dev->vdev.dev.parent = &pci_dev->dev;
  	vp_dev->vdev.dev.release = virtio_pci_release_dev;
  	vp_dev->pci_dev = pci_dev;

  	INIT_LIST_HEAD(&vp_dev->virtqueues);
  	spin_lock_init(&vp_dev->lock);

  	/* enable the device */
  	rc = pci_enable_device(pci_dev);
  	if (rc)
  		goto err_enable_device;

  	if (force_legacy) {

  		rc = virtio_pci_legacy_probe(vp_dev);

  		/* Also try modern mode if we can't map BAR0 (no IO space). */
  		if (rc == -ENODEV || rc == -ENOMEM)
  			rc = virtio_pci_modern_probe(vp_dev);
  		if (rc)
  			goto err_probe;
  	} else {
  		rc = virtio_pci_modern_probe(vp_dev);
  		if (rc == -ENODEV)
  			rc = virtio_pci_legacy_probe(vp_dev);
  		if (rc)
  			goto err_probe;
  	}

  
  	pci_set_master(pci_dev);
  
  	rc = register_virtio_device(&vp_dev->vdev);
  	if (rc)
  		goto err_register;
  
  	return 0;
  
  err_register:

  	if (vp_dev->ioaddr)
  	     virtio_pci_legacy_remove(vp_dev);
  	else
  	     virtio_pci_modern_remove(vp_dev);

  err_probe:

  	pci_disable_device(pci_dev);
  err_enable_device:
  	kfree(vp_dev);
  	return rc;

  }
  
  static void virtio_pci_remove(struct pci_dev *pci_dev)
  {

  	struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);

  	struct device *dev = get_device(&vp_dev->vdev.dev);

  
  	unregister_virtio_device(&vp_dev->vdev);

  	if (vp_dev->ioaddr)
  		virtio_pci_legacy_remove(vp_dev);
  	else
  		virtio_pci_modern_remove(vp_dev);

  	pci_disable_device(pci_dev);

  	put_device(dev);

  }
  
  static struct pci_driver virtio_pci_driver = {
  	.name		= "virtio-pci",
  	.id_table	= virtio_pci_id_table,
  	.probe		= virtio_pci_probe,
  	.remove		= virtio_pci_remove,
  #ifdef CONFIG_PM_SLEEP
  	.driver.pm	= &virtio_pci_pm_ops,
  #endif
  };
  
  module_pci_driver(virtio_pci_driver);

  
  MODULE_AUTHOR("Anthony Liguori <aliguori@us.ibm.com>");
  MODULE_DESCRIPTION("virtio-pci");
  MODULE_LICENSE("GPL");
  MODULE_VERSION("1");