// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * 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>
 */

#include "linux/virtio_pci_legacy.h"
#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 vp_legacy_get_features(&vp_dev->ldev);
}

/* 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. */
        vp_legacy_set_features(&vp_dev->ldev, vdev->features);

        return 0;
}

/* virtio config->get() implementation */
static void vp_get(struct virtio_device *vdev, unsigned int offset,
                   void *buf, unsigned int len)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        void __iomem *ioaddr = vp_dev->ldev.ioaddr +
                        VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
                        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 int offset,
                   const void *buf, unsigned int len)
{
        struct virtio_pci_device *vp_dev = to_vp_device(vdev);
        void __iomem *ioaddr = vp_dev->ldev.ioaddr +
                        VIRTIO_PCI_CONFIG_OFF(vp_dev->msix_enabled) +
                        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 vp_legacy_get_status(&vp_dev->ldev);
}

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);
        vp_legacy_set_status(&vp_dev->ldev, status);
}

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

static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
{
        return vp_legacy_config_vector(&vp_dev->ldev, vector);
}

static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
                                  struct virtio_pci_vq_info *info,
                                  unsigned int index,
                                  void (*callback)(struct virtqueue *vq),
                                  const char *name,
                                  bool ctx,
                                  u16 msix_vec)
{
        struct virtqueue *vq;
        u16 num;
        int err;
        u64 q_pfn;

        /* Check if queue is either not available or already active. */
        num = vp_legacy_get_queue_size(&vp_dev->ldev, index);
        if (!num || vp_legacy_get_queue_enable(&vp_dev->ldev, index))
                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);

        vq->num_max = num;

        q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
        if (q_pfn >> 32) {
                dev_err(&vp_dev->pci_dev->dev,
                        "platform bug: legacy virtio-pci must not be used with RAM above 0x%llxGB\n",
                        0x1ULL << (32 + PAGE_SHIFT - 30));
                err = -E2BIG;
                goto out_del_vq;
        }

        /* activate the queue */
        vp_legacy_set_queue_address(&vp_dev->ldev, index, q_pfn);

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

        if (msix_vec != VIRTIO_MSI_NO_VECTOR) {
                msix_vec = vp_legacy_queue_vector(&vp_dev->ldev, index, msix_vec);
                if (msix_vec == VIRTIO_MSI_NO_VECTOR) {
                        err = -EBUSY;
                        goto out_deactivate;
                }
        }

        return vq;

out_deactivate:
        vp_legacy_set_queue_address(&vp_dev->ldev, index, 0);
out_del_vq:
        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);

        if (vp_dev->msix_enabled) {
                vp_legacy_queue_vector(&vp_dev->ldev, vq->index,
                                VIRTIO_MSI_NO_VECTOR);
                /* Flush the write out to device */
                ioread8(vp_dev->ldev.ioaddr + VIRTIO_PCI_ISR);
        }

        /* Select and deactivate the queue */
        vp_legacy_set_queue_address(&vp_dev->ldev, vq->index, 0);

        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,
        .synchronize_cbs = vp_synchronize_vectors,
        .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 virtio_pci_legacy_device *ldev = &vp_dev->ldev;
        struct pci_dev *pci_dev = vp_dev->pci_dev;
        int rc;

        ldev->pci_dev = pci_dev;

        rc = vp_legacy_probe(ldev);
        if (rc)
                return rc;

        vp_dev->isr = ldev->isr;
        vp_dev->vdev.id = ldev->id;

        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;
        vp_dev->is_legacy = true;

        return 0;
}

void virtio_pci_legacy_remove(struct virtio_pci_device *vp_dev)
{
        struct virtio_pci_legacy_device *ldev = &vp_dev->ldev;

        vp_legacy_remove(ldev);
}