/*
 * Virtio PCI driver - legacy device support
 *
 * 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"

/* virtio config->get_features() implementation */
static u64 vp_get_features(struct virtio_device *vdev)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);

        /* When someone needs more than 32 feature bits, we'll need to
         * steal a bit to indicate that the rest are somewhere else. */
        return ioread32(vp_dev->ioaddr + VIRTIO_PCI_HOST_FEATURES);
}

/* virtio config->finalize_features() implementation */
static int vp_finalize_features(struct virtio_device *vdev)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);

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

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

        /* We only support 32 feature bits. */
        iowrite32(vdev->features, vp_dev->ioaddr + VIRTIO_PCI_GUEST_FEATURES);

        return 0;
}

/* virtio config->get() implementation */
static void vp_get(struct virtio_device *vdev, unsigned offset,
                   void *buf, unsigned len)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        void __iomem *ioaddr = vp_dev->ioaddr +
                                VIRTIO_PCI_CONFIG(vp_dev) + offset;
        u8 *ptr = buf;
        int i;

        for (i = 0; i < len; i++)
                ptr[i] = ioread8(ioaddr + i);
}

/* the config->set() implementation.  it's symmetric to the config->get()
 * implementation */
static void vp_set(struct virtio_device *vdev, unsigned offset,
                   const void *buf, unsigned len)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        void __iomem *ioaddr = vp_dev->ioaddr +
                                VIRTIO_PCI_CONFIG(vp_dev) + offset;
        const u8 *ptr = buf;
        int i;

        for (i = 0; i < len; i++)
                iowrite8(ptr[i], ioaddr + i);
}

/* config->{get,set}_status() implementations */
static u8 vp_get_status(struct virtio_device *vdev)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        return ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
}

static void vp_set_status(struct virtio_device *vdev, u8 status)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        /* We should never be setting status to 0. */
        BUG_ON(status == 0);
        iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
}

static void vp_reset(struct virtio_device *vdev)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        /* 0 status means a reset. */
        iowrite8(0, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
        /* Flush out the status write, and flush in device writes,
         * including MSi-X interrupts, if any. */
        ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
        /* Flush pending VQ/configuration callbacks. */
        vp_synchronize_vectors(vdev);
}

static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
{
        /* Setup the vector used for configuration events */
        iowrite16(vector, vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
        /* Verify we had enough resources to assign the vector */
        /* Will also flush the write out to device */
        return ioread16(vp_dev->ioaddr + VIRTIO_MSI_CONFIG_VECTOR);
}

static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
                                  struct virtio_pci_vq_info *info,
                                  unsigned index,
                                  void (*callback)(struct virtqueue *vq),
                                  const char *name,
                                  bool ctx,
                                  u16 msix_vec)
{
        struct virtqueue *vq;
        u16 num;
        int err;

        /* Select the queue we're interested in */
        iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);

        /* Check if queue is either not available or already active. */
        num = ioread16(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NUM);
        if (!num || ioread32(vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN))
                return ERR_PTR(-ENOENT);

        info->msix_vector = msix_vec;

        /* create the vring */
        vq = vring_create_virtqueue(index, num,
                                    VIRTIO_PCI_VRING_ALIGN, &vp_dev->vdev,
                                    true, false, ctx,
                                    vp_notify, callback, name);
        if (!vq)
                return ERR_PTR(-ENOMEM);

        /* activate the queue */
        iowrite32(virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
                  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);

        vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;

        if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
                iowrite16(msix_vec, vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
                msix_vec = ioread16(vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
                if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
                        err = -EBUSY;
                        goto out_deactivate;
                }
        }

        return vq;

out_deactivate:
        iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
        vring_del_virtqueue(vq);
        return ERR_PTR(err);
}

static void del_vq(struct virtio_pci_vq_info *info)
{
        struct virtqueue *vq = info->vq;
        struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);

        iowrite16(vq->index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);

        if (vp_dev->msix_enabled) {
                iowrite16(VIRTIO_MSI_NO_VECTOR,
                          vp_dev->ioaddr + VIRTIO_MSI_QUEUE_VECTOR);
                /* Flush the write out to device */
                ioread8(vp_dev->ioaddr + VIRTIO_PCI_ISR);
        }

        /* Select and deactivate the queue */
        iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);

        vring_del_virtqueue(vq);
}

static const struct virtio_config_ops virtio_pci_config_ops = {
        .get            = vp_get,
        .set            = vp_set,
        .get_status     = vp_get_status,
        .set_status     = vp_set_status,
        .reset          = vp_reset,
        .find_vqs       = vp_find_vqs,
        .del_vqs        = vp_del_vqs,
        .get_features   = vp_get_features,
        .finalize_features = vp_finalize_features,
        .bus_name       = vp_bus_name,
        .set_vq_affinity = vp_set_vq_affinity,
        .get_vq_affinity = vp_get_vq_affinity,
};

/* the PCI probing function */
int virtio_pci_legacy_probe(struct virtio_pci_device *vp_dev)
{
        struct pci_dev *pci_dev = vp_dev->pci_dev;
        int rc;

        /* We only own devices >= 0x1000 and <= 0x103f: leave the rest. */
        if (pci_dev->device < 0x1000 || pci_dev->device > 0x103f)
                return -ENODEV;

        if (pci_dev->revision != VIRTIO_PCI_ABI_VERSION) {
                printk(KERN_ERR "virtio_pci: expected ABI version %d, got %d\n",
                       VIRTIO_PCI_ABI_VERSION, pci_dev->revision);
                return -ENODEV;
        }

        rc = dma_set_mask(&pci_dev->dev, DMA_BIT_MASK(64));
        if (rc) {
                rc = dma_set_mask_and_coherent(&pci_dev->dev, DMA_BIT_MASK(32));
        } else {
                /*
                 * The virtio ring base address is expressed as a 32-bit PFN,
                 * with a page size of 1 << VIRTIO_PCI_QUEUE_ADDR_SHIFT.
                 */
                dma_set_coherent_mask(&pci_dev->dev,
                                DMA_BIT_MASK(32 + VIRTIO_PCI_QUEUE_ADDR_SHIFT));
        }

        if (rc)
                dev_warn(&pci_dev->dev, "Failed to enable 64-bit or 32-bit DMA.  Trying to continue, but this might not work.\n");

        rc = pci_request_region(pci_dev, 0, "virtio-pci-legacy");
        if (rc)
                return rc;

        rc = -ENOMEM;
        vp_dev->ioaddr = pci_iomap(pci_dev, 0, 0);
        if (!vp_dev->ioaddr)
                goto err_iomap;

        vp_dev->isr = vp_dev->ioaddr + VIRTIO_PCI_ISR;

        /* we use the subsystem vendor/device id as the virtio vendor/device
         * id.  this allows us to use the same PCI vendor/device id for all
         * virtio devices and to identify the particular virtio driver by
         * the subsystem ids */
        vp_dev->vdev.id.vendor = pci_dev->subsystem_vendor;
        vp_dev->vdev.id.device = pci_dev->subsystem_device;

        vp_dev->vdev.config = &virtio_pci_config_ops;

        vp_dev->config_vector = vp_config_vector;
        vp_dev->setup_vq = setup_vq;
        vp_dev->del_vq = del_vq;

        return 0;

err_iomap:
        pci_release_region(pci_dev, 0);
        return rc;
}

void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
{
        struct pci_dev *pci_dev = vp_dev->pci_dev;

        pci_iounmap(pci_dev, vp_dev->ioaddr);
        pci_release_region(pci_dev, 0);
}