dm: Add a new uclass driver for VirtIO transport devices

This adds a new virtio uclass driver for “virtio” [1] family of
devices that are are found in virtual environments like QEMU,
yet by design they look like physical devices to the guest.

The uclass driver provides child_pre_probe() and child_post_probe()
methods to do some common operations for virtio device drivers like
device and driver supported feature negotiation, etc.

[1] http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

8 files changed, 1135 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 927a2b87f6..4ac823d962 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -112,6 +112,8 @@ source "drivers/usb/Kconfig"
 
 source "drivers/video/Kconfig"
 
+source "drivers/virtio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/w1-eeprom/Kconfig"
diff --git a/drivers/Makefile b/drivers/Makefile
index fb38b67541..4453c62ad3 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_$(SPL_TPL_)SERIAL_SUPPORT) += serial/
 obj-$(CONFIG_$(SPL_TPL_)SPI_FLASH_SUPPORT) += mtd/spi/
 obj-$(CONFIG_$(SPL_TPL_)SPI_SUPPORT) += spi/
 obj-$(CONFIG_$(SPL_TPL_)TIMER) += timer/
+obj-$(CONFIG_$(SPL_TPL_)VIRTIO) += virtio/
 obj-$(CONFIG_$(SPL_)DM_MAILBOX) += mailbox/
 obj-$(CONFIG_$(SPL_)REMOTEPROC) += remoteproc/
 
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
new file mode 100644
index 0000000000..82fc536831
--- /dev/null
+++ b/drivers/virtio/Kconfig
@@ -0,0 +1,25 @@
+# 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.
+
+menu "VirtIO Drivers"
+
+config VIRTIO
+        bool
+        help
+          This option is selected by any driver which implements the virtio
+          transport, such as CONFIG_VIRTIO_MMIO or CONFIG_VIRTIO_PCI.
+
+endmenu
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
new file mode 100644
index 0000000000..23e7be7165
--- /dev/null
+++ b/drivers/virtio/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+
+obj-y += virtio-uclass.o
diff --git a/drivers/virtio/virtio-uclass.c b/drivers/virtio/virtio-uclass.c
new file mode 100644
index 0000000000..34397d7dbb
--- /dev/null
+++ b/drivers/virtio/virtio-uclass.c
@@ -0,0 +1,369 @@
+// 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 <virtio_types.h>
+#include <virtio.h>
+#include <dm/lists.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,
+};
+
+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),
+};
diff --git a/include/dm/uclass-id.h b/include/dm/uclass-id.h
index 269a2c6e72..c91dca1f82 100644
--- a/include/dm/uclass-id.h
+++ b/include/dm/uclass-id.h
@@ -96,6 +96,7 @@ enum uclass_id {
         UCLASS_VIDEO_BRIDGE,    /* Video bridge, e.g. DisplayPort to LVDS */
         UCLASS_VIDEO_CONSOLE,   /* Text console driver for video device */
         UCLASS_VIDEO_OSD,       /* On-screen display */
+        UCLASS_VIRTIO,          /* VirtIO transport device */
         UCLASS_W1,              /* Dallas 1-Wire bus */
         UCLASS_W1_EEPROM,       /* one-wire EEPROMs */
         UCLASS_WDT,             /* Watchdot Timer driver */
diff --git a/include/virtio.h b/include/virtio.h
new file mode 100644
index 0000000000..654fdf154b
--- /dev/null
+++ b/include/virtio.h
@@ -0,0 +1,707 @@
+/* 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.
+ *
+ * This file is largely based on Linux kernel virtio_*.h files
+ */
+
+#ifndef __VIRTIO_H__
+#define __VIRTIO_H__
+
+#define VIRTIO_ID_NET           1 /* virtio net */
+#define VIRTIO_ID_BLOCK         2 /* virtio block */
+#define VIRTIO_ID_MAX_NUM       3
+
+#define VIRTIO_NET_DRV_NAME     "virtio-net"
+#define VIRTIO_BLK_DRV_NAME     "virtio-blk"
+
+/* Status byte for guest to report progress, and synchronize features */
+
+/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
+#define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
+/* We have found a driver for the device */
+#define VIRTIO_CONFIG_S_DRIVER          2
+/* Driver has used its parts of the config, and is happy */
+#define VIRTIO_CONFIG_S_DRIVER_OK       4
+/* Driver has finished configuring features */
+#define VIRTIO_CONFIG_S_FEATURES_OK     8
+/* Device entered invalid state, driver must reset it */
+#define VIRTIO_CONFIG_S_NEEDS_RESET     0x40
+/* We've given up on this device */
+#define VIRTIO_CONFIG_S_FAILED          0x80
+
+/*
+ * Virtio feature bits VIRTIO_TRANSPORT_F_START through VIRTIO_TRANSPORT_F_END
+ * are reserved for the transport being used (eg: virtio_ring, virtio_pci etc.),
+ * the rest are per-device feature bits.
+ */
+#define VIRTIO_TRANSPORT_F_START        28
+#define VIRTIO_TRANSPORT_F_END          38
+
+#ifndef VIRTIO_CONFIG_NO_LEGACY
+/*
+ * Do we get callbacks when the ring is completely used,
+ * even if we've suppressed them?
+ */
+#define VIRTIO_F_NOTIFY_ON_EMPTY        24
+
+/* Can the device handle any descriptor layout? */
+#define VIRTIO_F_ANY_LAYOUT             27
+#endif /* VIRTIO_CONFIG_NO_LEGACY */
+
+/* v1.0 compliant */
+#define VIRTIO_F_VERSION_1              32
+
+/*
+ * If clear - device has the IOMMU bypass quirk feature.
+ * If set - use platform tools to detect the IOMMU.
+ *
+ * Note the reverse polarity (compared to most other features),
+ * this is for compatibility with legacy systems.
+ */
+#define VIRTIO_F_IOMMU_PLATFORM         33
+
+/* Does the device support Single Root I/O Virtualization? */
+#define VIRTIO_F_SR_IOV                 37
+
+/**
+ * virtio scatter-gather struct
+ *
+ * @addr:               sg buffer address
+ * @lengh:              sg buffer length
+ */
+struct virtio_sg {
+        void *addr;
+        size_t length;
+};
+
+struct virtqueue;
+
+/* virtio bus operations */
+struct dm_virtio_ops {
+        /**
+         * get_config() - read the value of a configuration field
+         *
+         * @vdev:       the real virtio device
+         * @offset:     the offset of the configuration field
+         * @buf:        the buffer to write the field value into
+         * @len:        the length of the buffer
+         * @return 0 if OK, -ve on error
+         */
+        int (*get_config)(struct udevice *vdev, unsigned int offset,
+                          void *buf, unsigned int len);
+        /**
+         * set_config() - write the value of a configuration field
+         *
+         * @vdev:       the real virtio device
+         * @offset:     the offset of the configuration field
+         * @buf:        the buffer to read the field value from
+         * @len:        the length of the buffer
+         * @return 0 if OK, -ve on error
+         */
+        int (*set_config)(struct udevice *vdev, unsigned int offset,
+                          const void *buf, unsigned int len);
+        /**
+         * generation() - config generation counter
+         *
+         * @vdev:       the real virtio device
+         * @counter:    the returned config generation counter
+         * @return 0 if OK, -ve on error
+         */
+        int (*generation)(struct udevice *vdev, u32 *counter);
+        /**
+         * get_status() - read the status byte
+         *
+         * @vdev:       the real virtio device
+         * @status:     the returned status byte
+         * @return 0 if OK, -ve on error
+         */
+        int (*get_status)(struct udevice *vdev, u8 *status);
+        /**
+         * set_status() - write the status byte
+         *
+         * @vdev:       the real virtio device
+         * @status:     the new status byte
+         * @return 0 if OK, -ve on error
+         */
+        int (*set_status)(struct udevice *vdev, u8 status);
+        /**
+         * reset() - reset the device
+         *
+         * @vdev:       the real virtio device
+         * @return 0 if OK, -ve on error
+         */
+        int (*reset)(struct udevice *vdev);
+        /**
+         * get_features() - get the array of feature bits for this device
+         *
+         * @vdev:       the real virtio device
+         * @features:   the first 32 feature bits (all we currently need)
+         * @return 0 if OK, -ve on error
+         */
+        int (*get_features)(struct udevice *vdev, u64 *features);
+        /**
+         * set_features() - confirm what device features we'll be using
+         *
+         * @vdev:       the real virtio device
+         * @return 0 if OK, -ve on error
+         */
+        int (*set_features)(struct udevice *vdev);
+        /**
+         * find_vqs() - find virtqueues and instantiate them
+         *
+         * @vdev:       the real virtio device
+         * @nvqs:       the number of virtqueues to find
+         * @vqs:        on success, includes new virtqueues
+         * @return 0 if OK, -ve on error
+         */
+        int (*find_vqs)(struct udevice *vdev, unsigned int nvqs,
+                        struct virtqueue *vqs[]);
+        /**
+         * del_vqs() - free virtqueues found by find_vqs()
+         *
+         * @vdev:       the real virtio device
+         * @return 0 if OK, -ve on error
+         */
+        int (*del_vqs)(struct udevice *vdev);
+        /**
+         * notify() - notify the device to process the queue
+         *
+         * @vdev:       the real virtio device
+         * @vq:         virtqueue to process
+         * @return 0 if OK, -ve on error
+         */
+        int (*notify)(struct udevice *vdev, struct virtqueue *vq);
+};
+
+/* Get access to a virtio bus' operations */
+#define virtio_get_ops(dev)     ((struct dm_virtio_ops *)(dev)->driver->ops)
+
+/**
+ * virtio uclass per device private data
+ *
+ * @vqs:                        virtualqueue for the virtio device
+ * @vdev:                       the real virtio device underneath
+ * @legacy:                     is it a legacy device?
+ * @device:                     virtio device ID
+ * @vendor:                     virtio vendor ID
+ * @features:                   negotiated supported features
+ * @feature_table:              an array of feature supported by the driver
+ * @feature_table_size:         number of entries in the feature table array
+ * @feature_table_legacy:       same as feature_table but working in legacy mode
+ * @feature_table_size_legacy:  number of entries in feature table legacy array
+ */
+struct virtio_dev_priv {
+        struct list_head vqs;
+        struct udevice *vdev;
+        bool legacy;
+        u32 device;
+        u32 vendor;
+        u64 features;
+        const u32 *feature_table;
+        u32 feature_table_size;
+        const u32 *feature_table_legacy;
+        u32 feature_table_size_legacy;
+};
+
+/**
+ * virtio_get_config() - read the value of a configuration field
+ *
+ * @vdev:       the real virtio device
+ * @offset:     the offset of the configuration field
+ * @buf:        the buffer to write the field value into
+ * @len:        the length of the buffer
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_config(struct udevice *vdev, unsigned int offset,
+                      void *buf, unsigned int len);
+
+/**
+ * virtio_set_config() - write the value of a configuration field
+ *
+ * @vdev:       the real virtio device
+ * @offset:     the offset of the configuration field
+ * @buf:        the buffer to read the field value from
+ * @len:        the length of the buffer
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_config(struct udevice *vdev, unsigned int offset,
+                      void *buf, unsigned int len);
+
+/**
+ * virtio_generation() - config generation counter
+ *
+ * @vdev:       the real virtio device
+ * @counter:    the returned config generation counter
+ * @return 0 if OK, -ve on error
+ */
+int virtio_generation(struct udevice *vdev, u32 *counter);
+
+/**
+ * virtio_get_status() - read the status byte
+ *
+ * @vdev:       the real virtio device
+ * @status:     the returned status byte
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_status(struct udevice *vdev, u8 *status);
+
+/**
+ * virtio_set_status() - write the status byte
+ *
+ * @vdev:       the real virtio device
+ * @status:     the new status byte
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_status(struct udevice *vdev, u8 status);
+
+/**
+ * virtio_reset() - reset the device
+ *
+ * @vdev:       the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_reset(struct udevice *vdev);
+
+/**
+ * virtio_get_features() - get the array of feature bits for this device
+ *
+ * @vdev:       the real virtio device
+ * @features:   the first 32 feature bits (all we currently need)
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_features(struct udevice *vdev, u64 *features);
+
+/**
+ * virtio_set_features() - confirm what device features we'll be using
+ *
+ * @vdev:       the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_features(struct udevice *vdev);
+
+/**
+ * virtio_find_vqs() - find virtqueues and instantiate them
+ *
+ * @vdev:       the real virtio device
+ * @nvqs:       the number of virtqueues to find
+ * @vqs:        on success, includes new virtqueues
+ * @return 0 if OK, -ve on error
+ */
+int virtio_find_vqs(struct udevice *vdev, unsigned int nvqs,
+                    struct virtqueue *vqs[]);
+
+/**
+ * virtio_del_vqs() - free virtqueues found by find_vqs()
+ *
+ * @vdev:       the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_del_vqs(struct udevice *vdev);
+
+/**
+ * virtio_notify() - notify the device to process the queue
+ *
+ * @vdev:       the real virtio device
+ * @vq:         virtqueue to process
+ * @return 0 if OK, -ve on error
+ */
+int virtio_notify(struct udevice *vdev, struct virtqueue *vq);
+
+/**
+ * virtio_add_status() - helper to set a new status code to the device
+ *
+ * @vdev:       the real virtio device
+ * @status:     new status code to be added
+ */
+void virtio_add_status(struct udevice *vdev, u8 status);
+
+/**
+ * virtio_finalize_features() - helper to finalize features
+ *
+ * @vdev:       the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_finalize_features(struct udevice *vdev);
+
+/**
+ * virtio_driver_features_init() - initialize driver supported features
+ *
+ * This fills in the virtio device parent per child private data with the given
+ * information, which contains driver supported features and legacy features.
+ *
+ * This API should be called in the virtio device driver's bind method, so that
+ * later virtio transport uclass driver can utilize the driver supplied features
+ * to negotiate with the device on the final supported features.
+ *
+ * @priv:               virtio uclass per device private data
+ * @feature:            an array of feature supported by the driver
+ * @feature_size:       number of entries in the feature table array
+ * @feature_legacy:     same as feature_table but working in legacy mode
+ * @feature_legacy_size:number of entries in feature table legacy array
+ */
+void virtio_driver_features_init(struct virtio_dev_priv *priv,
+                                 const u32 *feature,
+                                 u32 feature_size,
+                                 const u32 *feature_legacy,
+                                 u32 feature_legacy_size);
+
+/**
+ * virtio_init() - helper to enumerate all known virtio devices
+ *
+ * @return 0 if OK, -ve on error
+ */
+int virtio_init(void);
+
+static inline u16 __virtio16_to_cpu(bool little_endian, __virtio16 val)
+{
+        if (little_endian)
+                return le16_to_cpu((__force __le16)val);
+        else
+                return be16_to_cpu((__force __be16)val);
+}
+
+static inline __virtio16 __cpu_to_virtio16(bool little_endian, u16 val)
+{
+        if (little_endian)
+                return (__force __virtio16)cpu_to_le16(val);
+        else
+                return (__force __virtio16)cpu_to_be16(val);
+}
+
+static inline u32 __virtio32_to_cpu(bool little_endian, __virtio32 val)
+{
+        if (little_endian)
+                return le32_to_cpu((__force __le32)val);
+        else
+                return be32_to_cpu((__force __be32)val);
+}
+
+static inline __virtio32 __cpu_to_virtio32(bool little_endian, u32 val)
+{
+        if (little_endian)
+                return (__force __virtio32)cpu_to_le32(val);
+        else
+                return (__force __virtio32)cpu_to_be32(val);
+}
+
+static inline u64 __virtio64_to_cpu(bool little_endian, __virtio64 val)
+{
+        if (little_endian)
+                return le64_to_cpu((__force __le64)val);
+        else
+                return be64_to_cpu((__force __be64)val);
+}
+
+static inline __virtio64 __cpu_to_virtio64(bool little_endian, u64 val)
+{
+        if (little_endian)
+                return (__force __virtio64)cpu_to_le64(val);
+        else
+                return (__force __virtio64)cpu_to_be64(val);
+}
+
+/**
+ * __virtio_test_bit - helper to test feature bits
+ *
+ * For use by transports. Devices should normally use virtio_has_feature,
+ * which includes more checks.
+ *
+ * @udev: the transport device
+ * @fbit: the feature bit
+ */
+static inline bool __virtio_test_bit(struct udevice *udev, unsigned int fbit)
+{
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+        /* Did you forget to fix assumptions on max features? */
+        if (__builtin_constant_p(fbit))
+                BUILD_BUG_ON(fbit >= 64);
+        else
+                WARN_ON(fbit >= 64);
+
+        return uc_priv->features & BIT_ULL(fbit);
+}
+
+/**
+ * __virtio_set_bit - helper to set feature bits
+ *
+ * For use by transports.
+ *
+ * @udev: the transport device
+ * @fbit: the feature bit
+ */
+static inline void __virtio_set_bit(struct udevice *udev, unsigned int fbit)
+{
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+        /* Did you forget to fix assumptions on max features? */
+        if (__builtin_constant_p(fbit))
+                BUILD_BUG_ON(fbit >= 64);
+        else
+                WARN_ON(fbit >= 64);
+
+        uc_priv->features |= BIT_ULL(fbit);
+}
+
+/**
+ * __virtio_clear_bit - helper to clear feature bits
+ *
+ * For use by transports.
+ *
+ * @vdev: the transport device
+ * @fbit: the feature bit
+ */
+static inline void __virtio_clear_bit(struct udevice *udev, unsigned int fbit)
+{
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+        /* Did you forget to fix assumptions on max features? */
+        if (__builtin_constant_p(fbit))
+                BUILD_BUG_ON(fbit >= 64);
+        else
+                WARN_ON(fbit >= 64);
+
+        uc_priv->features &= ~BIT_ULL(fbit);
+}
+
+/**
+ * virtio_has_feature - helper to determine if this device has this feature
+ *
+ * Note this API is only usable after the virtio device driver's bind phase,
+ * as the feature has been negotiated between the device and the driver.
+ *
+ * @vdev: the virtio device
+ * @fbit: the feature bit
+ */
+static inline bool virtio_has_feature(struct udevice *vdev, unsigned int fbit)
+{
+        if (!(vdev->flags & DM_FLAG_BOUND))
+                WARN_ON(true);
+
+        return __virtio_test_bit(vdev->parent, fbit);
+}
+
+static inline bool virtio_legacy_is_little_endian(void)
+{
+#ifdef __LITTLE_ENDIAN
+        return true;
+#else
+        return false;
+#endif
+}
+
+static inline bool virtio_is_little_endian(struct udevice *vdev)
+{
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
+
+        return !uc_priv->legacy || virtio_legacy_is_little_endian();
+}
+
+/* Memory accessors */
+static inline u16 virtio16_to_cpu(struct udevice *vdev, __virtio16 val)
+{
+        return __virtio16_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio16 cpu_to_virtio16(struct udevice *vdev, u16 val)
+{
+        return __cpu_to_virtio16(virtio_is_little_endian(vdev), val);
+}
+
+static inline u32 virtio32_to_cpu(struct udevice *vdev, __virtio32 val)
+{
+        return __virtio32_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio32 cpu_to_virtio32(struct udevice *vdev, u32 val)
+{
+        return __cpu_to_virtio32(virtio_is_little_endian(vdev), val);
+}
+
+static inline u64 virtio64_to_cpu(struct udevice *vdev, __virtio64 val)
+{
+        return __virtio64_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio64 cpu_to_virtio64(struct udevice *vdev, u64 val)
+{
+        return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
+}
+
+/* Read @count fields, @bytes each */
+static inline void __virtio_cread_many(struct udevice *vdev,
+                                       unsigned int offset,
+                                       void *buf, size_t count, size_t bytes)
+{
+        u32 old, gen;
+        int i;
+
+        /* no need to check return value as generation can be optional */
+        virtio_generation(vdev, &gen);
+        do {
+                old = gen;
+
+                for (i = 0; i < count; i++)
+                        virtio_get_config(vdev, offset + bytes * i,
+                                          buf + i * bytes, bytes);
+
+                virtio_generation(vdev, &gen);
+        } while (gen != old);
+}
+
+static inline void virtio_cread_bytes(struct udevice *vdev,
+                                      unsigned int offset,
+                                      void *buf, size_t len)
+{
+        __virtio_cread_many(vdev, offset, buf, len, 1);
+}
+
+static inline u8 virtio_cread8(struct udevice *vdev, unsigned int offset)
+{
+        u8 ret;
+
+        virtio_get_config(vdev, offset, &ret, sizeof(ret));
+        return ret;
+}
+
+static inline void virtio_cwrite8(struct udevice *vdev,
+                                  unsigned int offset, u8 val)
+{
+        virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u16 virtio_cread16(struct udevice *vdev,
+                                 unsigned int offset)
+{
+        u16 ret;
+
+        virtio_get_config(vdev, offset, &ret, sizeof(ret));
+        return virtio16_to_cpu(vdev, (__force __virtio16)ret);
+}
+
+static inline void virtio_cwrite16(struct udevice *vdev,
+                                   unsigned int offset, u16 val)
+{
+        val = (__force u16)cpu_to_virtio16(vdev, val);
+        virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u32 virtio_cread32(struct udevice *vdev,
+                                 unsigned int offset)
+{
+        u32 ret;
+
+        virtio_get_config(vdev, offset, &ret, sizeof(ret));
+        return virtio32_to_cpu(vdev, (__force __virtio32)ret);
+}
+
+static inline void virtio_cwrite32(struct udevice *vdev,
+                                   unsigned int offset, u32 val)
+{
+        val = (__force u32)cpu_to_virtio32(vdev, val);
+        virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u64 virtio_cread64(struct udevice *vdev,
+                                 unsigned int offset)
+{
+        u64 ret;
+
+        __virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
+        return virtio64_to_cpu(vdev, (__force __virtio64)ret);
+}
+
+static inline void virtio_cwrite64(struct udevice *vdev,
+                                   unsigned int offset, u64 val)
+{
+        val = (__force u64)cpu_to_virtio64(vdev, val);
+        virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+/* Config space read accessor */
+#define virtio_cread(vdev, structname, member, ptr)                     \
+        do {                                                            \
+                /* Must match the member's type, and be integer */      \
+                if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
+                        (*ptr) = 1;                                     \
+                                                                        \
+                switch (sizeof(*ptr)) {                                 \
+                case 1:                                                 \
+                        *(ptr) = virtio_cread8(vdev,                    \
+                                               offsetof(structname, member)); \
+                        break;                                          \
+                case 2:                                                 \
+                        *(ptr) = virtio_cread16(vdev,                   \
+                                                offsetof(structname, member)); \
+                        break;                                          \
+                case 4:                                                 \
+                        *(ptr) = virtio_cread32(vdev,                   \
+                                                offsetof(structname, member)); \
+                        break;                                          \
+                case 8:                                                 \
+                        *(ptr) = virtio_cread64(vdev,                   \
+                                                offsetof(structname, member)); \
+                        break;                                          \
+                default:                                                \
+                        WARN_ON(true);                                  \
+                }                                                       \
+        } while (0)
+
+/* Config space write accessor */
+#define virtio_cwrite(vdev, structname, member, ptr)                    \
+        do {                                                            \
+                /* Must match the member's type, and be integer */      \
+                if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
+                        WARN_ON((*ptr) == 1);                           \
+                                                                        \
+                switch (sizeof(*ptr)) {                                 \
+                case 1:                                                 \
+                        virtio_cwrite8(vdev,                            \
+                                       offsetof(structname, member),    \
+                                       *(ptr));                         \
+                        break;                                          \
+                case 2:                                                 \
+                        virtio_cwrite16(vdev,                           \
+                                        offsetof(structname, member),   \
+                                        *(ptr));                        \
+                        break;                                          \
+                case 4:                                                 \
+                        virtio_cwrite32(vdev,                           \
+                                        offsetof(structname, member),   \
+                                        *(ptr));                        \
+                        break;                                          \
+                case 8:                                                 \
+                        virtio_cwrite64(vdev,                           \
+                                        offsetof(structname, member),   \
+                                        *(ptr));                        \
+                        break;                                          \
+                default:                                                \
+                        WARN_ON(true);                                  \
+                }                                                       \
+        } while (0)
+
+/* Conditional config space accessors */
+#define virtio_cread_feature(vdev, fbit, structname, member, ptr)       \
+        ({                                                              \
+                int _r = 0;                                             \
+                if (!virtio_has_feature(vdev, fbit))                    \
+                        _r = -ENOENT;                                   \
+                else                                                    \
+                        virtio_cread(vdev, structname, member, ptr);    \
+                _r;                                                     \
+        })
+
+#endif /* __VIRTIO_H__ */
diff --git a/include/virtio_types.h b/include/virtio_types.h
new file mode 100644
index 0000000000..d700d1936d
--- /dev/null
+++ b/include/virtio_types.h
@@ -0,0 +1,24 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * From Linux kernel include/uapi/linux/virtio_types.h
+ */
+
+#ifndef _LINUX_VIRTIO_TYPES_H
+#define _LINUX_VIRTIO_TYPES_H
+
+#include <linux/types.h>
+
+/*
+ * __virtio{16,32,64} have the following meaning:
+ * - __u{16,32,64} for virtio devices in legacy mode, accessed in native endian
+ * - __le{16,32,64} for standard-compliant virtio devices
+ */
+
+typedef __u16 __bitwise __virtio16;
+typedef __u32 __bitwise __virtio32;
+typedef __u64 __bitwise __virtio64;
+
+#endif /* _LINUX_VIRTIO_TYPES_H */