// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
 * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
 *
 * VirtIO is a virtualization standard for network and disk device drivers
 * where just the guest's device driver "knows" it is running in a virtual
 * environment, and cooperates with the hypervisor. This enables guests to
 * get high performance network and disk operations, and gives most of the
 * performance benefits of paravirtualization. In the U-Boot case, the guest
 * is U-Boot itself, while the virtual environment are normally QEMU targets
 * like ARM, RISC-V and x86.
 *
 * See http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf for
 * the VirtIO specification v1.0.
 */

#include <common.h>
#include <dm.h>
#include <log.h>
#include <malloc.h>
#include <virtio_types.h>
#include <virtio.h>
#include <dm/lists.h>
#include <linux/bug.h>

static const char *const virtio_drv_name[VIRTIO_ID_MAX_NUM] = {
        [VIRTIO_ID_NET]         = VIRTIO_NET_DRV_NAME,
        [VIRTIO_ID_BLOCK]       = VIRTIO_BLK_DRV_NAME,
        [VIRTIO_ID_RNG]         = VIRTIO_RNG_DRV_NAME,
};

int virtio_get_config(struct udevice *vdev, unsigned int offset,
                      void *buf, unsigned int len)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->get_config(vdev->parent, offset, buf, len);
}

int virtio_set_config(struct udevice *vdev, unsigned int offset,
                      void *buf, unsigned int len)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->set_config(vdev->parent, offset, buf, len);
}

int virtio_generation(struct udevice *vdev, u32 *counter)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);
        if (!ops->generation)
                return -ENOSYS;

        return ops->generation(vdev->parent, counter);
}

int virtio_get_status(struct udevice *vdev, u8 *status)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->get_status(vdev->parent, status);
}

int virtio_set_status(struct udevice *vdev, u8 status)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->set_status(vdev->parent, status);
}

int virtio_reset(struct udevice *vdev)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->reset(vdev->parent);
}

int virtio_get_features(struct udevice *vdev, u64 *features)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->get_features(vdev->parent, features);
}

int virtio_set_features(struct udevice *vdev)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->set_features(vdev->parent);
}

int virtio_find_vqs(struct udevice *vdev, unsigned int nvqs,
                    struct virtqueue *vqs[])
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->find_vqs(vdev->parent, nvqs, vqs);
}

int virtio_del_vqs(struct udevice *vdev)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->del_vqs(vdev->parent);
}

int virtio_notify(struct udevice *vdev, struct virtqueue *vq)
{
        struct dm_virtio_ops *ops;

        ops = virtio_get_ops(vdev->parent);

        return ops->notify(vdev->parent, vq);
}

void virtio_add_status(struct udevice *vdev, u8 status)
{
        u8 old;

        if (!virtio_get_status(vdev, &old))
                virtio_set_status(vdev, old | status);
}

int virtio_finalize_features(struct udevice *vdev)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
        u8 status;
        int ret;

        ret = virtio_set_features(vdev);
        if (ret)
                return ret;

        if (uc_priv->legacy)
                return 0;

        virtio_add_status(vdev, VIRTIO_CONFIG_S_FEATURES_OK);
        ret = virtio_get_status(vdev, &status);
        if (ret)
                return ret;
        if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
                debug("(%s): device refuses features %x\n", vdev->name, status);
                return -ENODEV;
        }

        return 0;
}

void virtio_driver_features_init(struct virtio_dev_priv *priv,
                                 const u32 *feature,
                                 u32 feature_size,
                                 const u32 *feature_legacy,
                                 u32 feature_legacy_size)
{
        priv->feature_table = feature;
        priv->feature_table_size = feature_size;
        priv->feature_table_legacy = feature_legacy;
        priv->feature_table_size_legacy = feature_legacy_size;
}

int virtio_init(void)
{
        struct udevice *bus;
        int ret;

        /* Enumerate all known virtio devices */
        ret = uclass_first_device(UCLASS_VIRTIO, &bus);
        if (ret)
                return ret;

        while (bus) {
                ret = uclass_next_device(&bus);
                if (ret)
                        break;
        }

        return ret;
}

static int virtio_uclass_pre_probe(struct udevice *udev)
{
        struct dm_virtio_ops *ops;

        ops = (struct dm_virtio_ops *)(udev->driver->ops);

        /*
         * Check virtio transport driver ops here so that we don't need
         * check these ops each time when the virtio_xxx APIs are called.
         *
         * Only generation op is optional. All other ops are must-have.
         */
        if (!ops->get_config || !ops->set_config ||
            !ops->get_status || !ops->set_status ||
            !ops->get_features || !ops->set_features ||
            !ops->find_vqs || !ops->del_vqs ||
            !ops->reset || !ops->notify)
                return -ENOENT;

        return 0;
}

static int virtio_uclass_post_probe(struct udevice *udev)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
        char dev_name[30], *str;
        struct udevice *vdev;
        int ret;

        if (uc_priv->device > VIRTIO_ID_MAX_NUM) {
                debug("(%s): virtio device ID %d exceeds maximum num\n",
                      udev->name, uc_priv->device);
                return 0;
        }

        if (!virtio_drv_name[uc_priv->device]) {
                debug("(%s): underlying virtio device driver unavailable\n",
                      udev->name);
                return 0;
        }

        snprintf(dev_name, sizeof(dev_name), "%s#%d",
                 virtio_drv_name[uc_priv->device], udev->seq);
        str = strdup(dev_name);
        if (!str)
                return -ENOMEM;

        ret = device_bind_driver(udev, virtio_drv_name[uc_priv->device],
                                 str, &vdev);
        if (ret == -ENOENT) {
                debug("(%s): no driver configured\n", udev->name);
                return 0;
        }
        if (ret) {
                free(str);
                return ret;
        }
        device_set_name_alloced(vdev);

        INIT_LIST_HEAD(&uc_priv->vqs);

        return 0;
}

static int virtio_uclass_child_post_bind(struct udevice *vdev)
{
        /* Acknowledge that we've seen the device */
        virtio_add_status(vdev, VIRTIO_CONFIG_S_ACKNOWLEDGE);

        return 0;
}

static int virtio_uclass_child_pre_probe(struct udevice *vdev)
{
        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
        u64 device_features;
        u64 driver_features;
        u64 driver_features_legacy;
        int i;
        int ret;

        /*
         * Save the real virtio device (eg: virtio-net, virtio-blk) to
         * the transport (parent) device's uclass priv for future use.
         */
        uc_priv->vdev = vdev;

        /*
         * We always start by resetting the device, in case a previous driver
         * messed it up. This also tests that code path a little.
         */
        ret = virtio_reset(vdev);
        if (ret)
                goto err;

        /* We have a driver! */
        virtio_add_status(vdev, VIRTIO_CONFIG_S_DRIVER);

        /* Figure out what features the device supports */
        virtio_get_features(vdev, &device_features);
        debug("(%s) plain device features supported %016llx\n",
              vdev->name, device_features);
        if (!(device_features & (1ULL << VIRTIO_F_VERSION_1)))
                uc_priv->legacy = true;

        /* Figure out what features the driver supports */
        driver_features = 0;
        for (i = 0; i < uc_priv->feature_table_size; i++) {
                unsigned int f = uc_priv->feature_table[i];

                WARN_ON(f >= 64);
                driver_features |= (1ULL << f);
        }

        /* Some drivers have a separate feature table for virtio v1.0 */
        if (uc_priv->feature_table_legacy) {
                driver_features_legacy = 0;
                for (i = 0; i < uc_priv->feature_table_size_legacy; i++) {
                        unsigned int f = uc_priv->feature_table_legacy[i];

                        WARN_ON(f >= 64);
                        driver_features_legacy |= (1ULL << f);
                }
        } else {
                driver_features_legacy = driver_features;
        }

        if (uc_priv->legacy) {
                debug("(%s): legacy virtio device\n", vdev->name);
                uc_priv->features = driver_features_legacy & device_features;
        } else {
                debug("(%s): v1.0 complaint virtio device\n", vdev->name);
                uc_priv->features = driver_features & device_features;
        }

        /* Transport features always preserved to pass to finalize_features */
        for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
                if ((device_features & (1ULL << i)) &&
                    (i == VIRTIO_F_VERSION_1))
                        __virtio_set_bit(vdev->parent, i);

        debug("(%s) final negotiated features supported %016llx\n",
              vdev->name, uc_priv->features);
        ret = virtio_finalize_features(vdev);
        if (ret)
                goto err;

        return 0;

err:
        virtio_add_status(vdev, VIRTIO_CONFIG_S_FAILED);
        return ret;
}

static int virtio_uclass_child_post_probe(struct udevice *vdev)
{
        /* Indicates that the driver is set up and ready to drive the device */
        virtio_add_status(vdev, VIRTIO_CONFIG_S_DRIVER_OK);

        return 0;
}

UCLASS_DRIVER(virtio) = {
        .name   = "virtio",
        .id     = UCLASS_VIRTIO,
        .flags  = DM_UC_FLAG_SEQ_ALIAS,
        .pre_probe = virtio_uclass_pre_probe,
        .post_probe = virtio_uclass_post_probe,
        .child_post_bind = virtio_uclass_child_post_bind,
        .child_pre_probe = virtio_uclass_child_pre_probe,
        .child_post_probe = virtio_uclass_child_post_probe,
        .per_device_auto_alloc_size = sizeof(struct virtio_dev_priv),
};