initial commit, FreeRTOS_BSP_1.0.0_iMX7D

5 files changed, 1332 insertions, 0 deletions

diff --git a/middleware/multicore/open-amp/virtio/virtio.c b/middleware/multicore/open-amp/virtio/virtio.c
new file mode 100644
index 0000000..b2de79e
--- /dev/null
+++ b/middleware/multicore/open-amp/virtio/virtio.c
@@ -0,0 +1,96 @@
+/*-
+ * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#include "virtio.h"
+
+static const char *virtio_feature_name(unsigned long feature, struct virtio_feature_desc *);
+
+//TODO : This structure may change depending on the types of devices we support.
+static struct virtio_ident {
+    unsigned short  devid;
+    const char  *name;
+} virtio_ident_table[] = {
+    { VIRTIO_ID_NETWORK,    "Network"   },
+    { VIRTIO_ID_BLOCK,  "Block"     },
+    { VIRTIO_ID_CONSOLE,    "Console"   },
+    { VIRTIO_ID_ENTROPY,    "Entropy"   },
+    { VIRTIO_ID_BALLOON,    "Balloon"   },
+    { VIRTIO_ID_IOMEMORY,   "IOMemory"  },
+    { VIRTIO_ID_SCSI,   "SCSI"      },
+    { VIRTIO_ID_9P,     "9P Transport"  },
+
+    { 0, NULL }
+};
+
+/* Device independent features. */
+static struct virtio_feature_desc virtio_common_feature_desc[] = {
+    { VIRTIO_F_NOTIFY_ON_EMPTY, "NotifyOnEmpty" },
+    { VIRTIO_RING_F_INDIRECT_DESC,  "RingIndirect"  },
+    { VIRTIO_RING_F_EVENT_IDX,  "EventIdx"  },
+    { VIRTIO_F_BAD_FEATURE,     "BadFeature"    },
+
+    { 0, NULL }
+};
+
+const char *
+virtio_dev_name(unsigned short devid)
+{
+    struct virtio_ident *ident;
+
+    for (ident = virtio_ident_table; ident->name != NULL; ident++) {
+        if (ident->devid == devid)
+            return (ident->name);
+    }
+
+    return (NULL);
+}
+
+static const char *
+virtio_feature_name(unsigned long val, struct virtio_feature_desc *desc)
+{
+    int i, j;
+    struct virtio_feature_desc *descs[2] = { desc,
+        virtio_common_feature_desc };
+
+    for (i = 0; i < 2; i++) {
+        if (descs[i] == NULL)
+            continue;
+
+        for (j = 0; descs[i][j].vfd_val != 0; j++) {
+            if (val == descs[i][j].vfd_val)
+                return (descs[i][j].vfd_str);
+        }
+    }
+
+    return (NULL);
+}
+
+void virtio_describe(struct virtio_device *dev, const char *msg,
+    uint32_t features, struct virtio_feature_desc *desc)
+{
+    // TODO: Not used currently - keeping it for future use
+    virtio_feature_name(0,desc);
+}
+
diff --git a/middleware/multicore/open-amp/virtio/virtio.h b/middleware/multicore/open-amp/virtio/virtio.h
new file mode 100644
index 0000000..ab11dcd
--- /dev/null
+++ b/middleware/multicore/open-amp/virtio/virtio.h
@@ -0,0 +1,151 @@
+/*-
+ * This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of IBM nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _VIRTIO_H_
+#define _VIRTIO_H_
+
+#include "virtqueue.h"
+
+/* VirtIO device IDs. */
+#define VIRTIO_ID_NETWORK    0x01
+#define VIRTIO_ID_BLOCK      0x02
+#define VIRTIO_ID_CONSOLE    0x03
+#define VIRTIO_ID_ENTROPY    0x04
+#define VIRTIO_ID_BALLOON    0x05
+#define VIRTIO_ID_IOMEMORY   0x06
+#define VIRTIO_ID_RPMSG		 0x07 /* virtio remote remote_proc messaging */
+#define VIRTIO_ID_SCSI       0x08
+#define VIRTIO_ID_9P         0x09
+
+/* Status byte for guest to report progress. */
+#define VIRTIO_CONFIG_STATUS_RESET     0x00
+#define VIRTIO_CONFIG_STATUS_ACK       0x01
+#define VIRTIO_CONFIG_STATUS_DRIVER    0x02
+#define VIRTIO_CONFIG_STATUS_DRIVER_OK 0x04
+#define VIRTIO_CONFIG_STATUS_FAILED    0x80
+
+/*
+ * Generate interrupt when the virtqueue ring is
+ * completely used, even if we've suppressed them.
+ */
+#define VIRTIO_F_NOTIFY_ON_EMPTY (1 << 24)
+
+/*
+ * The guest should never negotiate this feature; it
+ * is used to detect faulty drivers.
+ */
+#define VIRTIO_F_BAD_FEATURE (1 << 30)
+
+/*
+ * Some VirtIO feature bits (currently bits 28 through 31) are
+ * reserved for the transport being used (eg. virtio_ring), the
+ * rest are per-device feature bits.
+ */
+#define VIRTIO_TRANSPORT_F_START      28
+#define VIRTIO_TRANSPORT_F_END        32
+
+typedef struct _virtio_dispatch_ virtio_dispatch;
+
+struct virtio_feature_desc {
+    uint32_t      vfd_val;
+    const char    *vfd_str;
+};
+
+/*
+ * Structure definition for virtio devices for use by the
+ * applications/drivers
+ *
+ */
+
+struct virtio_device {
+    /*
+     * Since there is no generic device structure so
+     * keep its type as void. The driver layer will take
+     * care of it.
+     */
+    void *device;
+
+    /* Device name */
+    char *name;
+
+    /* List of virtqueues encapsulated by virtio device. */
+    //TODO : Need to implement a list service for ipc stack.
+    void *vq_list;
+
+    /* Virtio device specific features */
+    uint32_t features;
+
+    /* Virtio dispatch table */
+    virtio_dispatch *func;
+
+    /*
+     * Pointer to hold some private data, useful
+     * in callbacks.
+     */
+    void *data;
+};
+
+/* 
+ * Helper functions.
+ */ 
+const char *virtio_dev_name(uint16_t devid);
+void       virtio_describe(struct virtio_device *dev, const char *msg,
+           uint32_t features, struct virtio_feature_desc *feature_desc);
+
+/*
+ * Functions for virtio device configuration as defined in Rusty Russell's paper.
+ * Drivers are expected to implement these functions in their respective codes.
+ * 
+ */
+
+struct _virtio_dispatch_ {
+    int (*create_virtqueues)(struct virtio_device *dev, int flags, int nvqs,
+                    const char *names[], vq_callback *callbacks[],
+                    struct virtqueue *vqs[]);
+    uint8_t (*get_status)(struct virtio_device *dev);
+    void (*set_status)(struct virtio_device *dev, uint8_t status);
+    uint32_t (*get_features)(struct virtio_device *dev);
+    void (*set_features)(struct virtio_device *dev, uint32_t feature);
+    uint32_t (*negotiate_features)(struct virtio_device *dev, uint32_t features);
+
+    /*
+     * Read/write a variable amount from the device specific (ie, network)
+     * configuration region. This region is encoded in the same endian as
+     * the guest.
+     */
+    void (*read_config)(struct virtio_device *dev, uint32_t offset, void *dst,
+                    int length);
+    void (*write_config)(struct virtio_device *dev, uint32_t offset, void *src,
+                    int length);
+    void (*reset_device)(struct virtio_device *dev);
+
+};
+
+#endif /* _VIRTIO_H_ */
diff --git a/middleware/multicore/open-amp/virtio/virtio_ring.h b/middleware/multicore/open-amp/virtio/virtio_ring.h
new file mode 100644
index 0000000..5bea08b
--- /dev/null
+++ b/middleware/multicore/open-amp/virtio/virtio_ring.h
@@ -0,0 +1,165 @@
+/*-
+ * Copyright Rusty Russell IBM Corporation 2007.
+ *
+ * This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of IBM nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef VIRTIO_RING_H
+#define	VIRTIO_RING_H
+
+/* This marks a buffer as continuing via the next field. */
+#define VRING_DESC_F_NEXT       1
+/* This marks a buffer as write-only (otherwise read-only). */
+#define VRING_DESC_F_WRITE      2
+/* This means the buffer contains a list of buffer descriptors. */
+#define VRING_DESC_F_INDIRECT	4   /*not used?*/
+
+/* The Host uses this in used->flags to advise the Guest: don't kick me
+ * when you add a buffer.  It's unreliable, so it's simply an
+ * optimization.  Guest will still kick if it's out of buffers. */
+#define VRING_USED_F_NO_NOTIFY  1
+/* The Guest uses this in avail->flags to advise the Host: don't
+ * interrupt me when you consume a buffer.  It's unreliable, so it's
+ * simply an optimization.  */
+#define VRING_AVAIL_F_NO_INTERRUPT      1
+
+/* VirtIO ring descriptors: 16 bytes.
+ * These can chain together via "next". */
+struct vring_desc {
+        /* Address (guest-physical). */
+        uint64_t addr;
+        /* Length. */
+        uint32_t len;
+        /* The flags as indicated above. */
+        uint16_t flags;
+        /* We chain unused descriptors via this, too. */
+        uint16_t next;
+};
+
+struct vring_avail {
+        uint16_t flags;
+        uint16_t idx;
+        uint16_t ring[0];
+};
+
+/* uint32_t is used here for ids for padding reasons. */
+struct vring_used_elem {
+        /* Index of start of used descriptor chain. */
+        uint32_t id;
+        /* Total length of the descriptor chain which was written to. */
+        uint32_t len;
+};
+
+struct vring_used {
+        uint16_t flags;
+        uint16_t idx;
+        struct vring_used_elem ring[0];
+};
+
+struct vring {
+	unsigned int num;
+
+	struct vring_desc *desc;
+	struct vring_avail *avail;
+	struct vring_used *used;
+};
+
+/* The standard layout for the ring is a continuous chunk of memory which
+ * looks like this.  We assume num is a power of 2.
+ *
+ * struct vring {
+ *      // The actual descriptors (16 bytes each)
+ *      struct vring_desc desc[num];
+ *
+ *      // A ring of available descriptor heads with free-running index.
+ *      __u16 avail_flags;
+ *      __u16 avail_idx;
+ *      __u16 available[num];
+ *      __u16 used_event_idx;
+ *
+ *      // Padding to the next align boundary.
+ *      char pad[];
+ *
+ *      // A ring of used descriptor heads with free-running index.
+ *      __u16 used_flags;
+ *      __u16 used_idx;
+ *      struct vring_used_elem used[num];
+ *      __u16 avail_event_idx;
+ * };
+ *
+ * NOTE: for VirtIO PCI, align is 4096.
+ */
+
+/*
+ * We publish the used event index at the end of the available ring, and vice
+ * versa. They are at the end for backwards compatibility.
+ */
+#define vring_used_event(vr)	((vr)->avail->ring[(vr)->num])
+#define vring_avail_event(vr)	(*(uint16_t *)&(vr)->used->ring[(vr)->num])
+
+static inline int
+vring_size(unsigned int num, unsigned long align)
+{
+	int size;
+
+	size = num * sizeof(struct vring_desc);
+	size += sizeof(struct vring_avail) + (num * sizeof(uint16_t)) +
+	    sizeof(uint16_t);
+	size = (size + align - 1) & ~(align - 1);
+	size += sizeof(struct vring_used) +
+	    (num * sizeof(struct vring_used_elem)) + sizeof(uint16_t);
+	return (size);
+}
+
+static inline void
+vring_init(struct vring *vr, unsigned int num, uint8_t *p,
+    unsigned long align)
+{
+        vr->num = num;
+        vr->desc = (struct vring_desc *) p;
+        vr->avail = (struct vring_avail *) (p +
+	    num * sizeof(struct vring_desc));
+        vr->used = (void *)
+	    (((unsigned long) &vr->avail->ring[num] + align-1) & ~(align-1));
+}
+
+/*
+ * The following is used with VIRTIO_RING_F_EVENT_IDX.
+ *
+ * Assuming a given event_idx value from the other size, if we have
+ * just incremented index from old to new_idx, should we trigger an
+ * event?
+ */
+static inline int
+vring_need_event(uint16_t event_idx, uint16_t new_idx, uint16_t old)
+{
+
+	return (uint16_t)(new_idx - event_idx - 1) < (uint16_t)(new_idx - old);
+}
+#endif /* VIRTIO_RING_H */
diff --git a/middleware/multicore/open-amp/virtio/virtqueue.c b/middleware/multicore/open-amp/virtio/virtqueue.c
new file mode 100644
index 0000000..2ea87cd
--- /dev/null
+++ b/middleware/multicore/open-amp/virtio/virtqueue.c
@@ -0,0 +1,693 @@
+/*-
+ * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "virtqueue.h"
+
+/* Prototype for internal functions. */
+static void vq_ring_init(struct virtqueue *);
+static void vq_ring_update_avail(struct virtqueue *, uint16_t);
+static uint16_t vq_ring_add_buffer(struct virtqueue *, struct vring_desc *,
+        uint16_t, struct llist *, int, int);
+static int vq_ring_enable_interrupt(struct virtqueue *, uint16_t);
+static void vq_ring_free_chain(struct virtqueue *, uint16_t);
+static int vq_ring_must_notify_host(struct virtqueue *vq);
+static void vq_ring_notify_host(struct virtqueue *vq);
+static int virtqueue_nused(struct virtqueue *vq);
+
+/**
+ * virtqueue_create - Creates new VirtIO queue
+ *
+ * @param device    - Pointer to VirtIO device
+ * @param id        - VirtIO queue ID , must be unique
+ * @param name      - Name of VirtIO queue
+ * @param ring      - Pointer to vring_alloc_info control block
+ * @param callback  - Pointer to callback function, invoked
+ *                    when message is available on VirtIO queue
+ * @param notify    - Pointer to notify function, used to notify
+ *                    other side that there is job available for it
+ * @param v_queue   - Created VirtIO queue.
+ *
+ * @return          - Function status
+ */
+int virtqueue_create(struct virtio_device *virt_dev, unsigned short id, char *name,
+        struct vring_alloc_info *ring, void (*callback)(struct virtqueue *vq),
+        void (*notify)(struct virtqueue *vq),
+        struct virtqueue **v_queue) {
+
+    struct virtqueue *vq = VQ_NULL;
+    int status = VQUEUE_SUCCESS;
+    uint32_t vq_size = 0;
+
+    VQ_PARAM_CHK(ring == VQ_NULL, status, ERROR_VQUEUE_INVLD_PARAM);
+    VQ_PARAM_CHK(ring->num_descs == 0, status, ERROR_VQUEUE_INVLD_PARAM);
+    VQ_PARAM_CHK(ring->num_descs & (ring->num_descs - 1), status,
+            ERROR_VRING_ALIGN);
+
+    //TODO : Error check for indirect buffer addition
+
+    if (status == VQUEUE_SUCCESS) {
+
+        vq_size = sizeof(struct virtqueue)
+                + (ring->num_descs) * sizeof(struct vq_desc_extra);
+        vq = (struct virtqueue *) env_allocate_memory(vq_size);
+
+
+        if (vq == VQ_NULL) {
+            return (ERROR_NO_MEM);
+        }
+
+        env_memset(vq, 0x00, vq_size);
+
+
+        vq->vq_dev = virt_dev;
+        env_strncpy(vq->vq_name, name, VIRTQUEUE_MAX_NAME_SZ);
+        vq->vq_queue_index = id;
+        vq->vq_alignment = ring->align;         /*ring info comes from proc_table*/
+        vq->vq_nentries = ring->num_descs;
+        vq->vq_free_cnt = vq->vq_nentries;
+        vq->callback = callback;            /*rpmsg_tx_callback, rpmsg_rx_callback*/
+        vq->notify = notify;                /*hil_vring_notify*/
+
+        //TODO : Whether we want to support indirect addition or not.
+        vq->vq_ring_size = vring_size(ring->num_descs, ring->align);
+        vq->vq_ring_mem = (void *) ring->phy_addr;
+
+        /* Initialize vring control block in virtqueue. */
+        vq_ring_init(vq);
+
+        /* Disable callbacks - will be enabled by the application
+         * once initialization is completed.
+         */
+        virtqueue_disable_cb(vq);
+
+        *v_queue = vq;
+
+        //TODO : Need to add cleanup in case of error used with the indirect buffer addition
+        //TODO: do we need to save the new queue in db based on its id
+    }
+
+    return (status);
+}
+
+/**
+ * virtqueue_add_buffer()   - Enqueues new buffer in vring for consumption
+ *                            by other side. Readable buffers are always
+ *                            inserted before writable buffers
+ *
+ * @param vq                - Pointer to VirtIO queue control block.
+ * @param buffer            - Pointer to buffer list
+ * @param readable          - Number of readable buffers
+ * @param writable          - Number of writable buffers
+ * @param cookie            - Pointer to hold call back data
+ *
+ * @return                  - Function status
+ */
+int virtqueue_add_buffer(struct virtqueue *vq, struct llist *buffer,
+        int readable, int writable, void *cookie) {
+
+    struct vq_desc_extra *dxp = VQ_NULL;
+    int status = VQUEUE_SUCCESS;
+    uint16_t head_idx;
+    uint16_t idx;
+    int needed;
+
+    needed = readable + writable;   /*only one can be set to 1*/
+
+    VQ_PARAM_CHK(vq == VQ_NULL, status, ERROR_VQUEUE_INVLD_PARAM);
+    VQ_PARAM_CHK(needed < 1, status, ERROR_VQUEUE_INVLD_PARAM);
+    VQ_PARAM_CHK(vq->vq_free_cnt == 0, status, ERROR_VRING_FULL);
+
+    //TODO: Add parameters validation for indirect buffer addition
+
+    VQUEUE_BUSY(vq);
+
+    if (status == VQUEUE_SUCCESS) {
+
+        //TODO : Indirect buffer addition support
+
+        VQASSERT(vq, cookie != VQ_NULL, "enqueuing with no cookie");
+
+        head_idx = vq->vq_desc_head_idx;
+        VQ_RING_ASSERT_VALID_IDX(vq, head_idx);
+        dxp = &vq->vq_descx[head_idx];
+
+        VQASSERT(vq, (dxp->cookie == VQ_NULL), "cookie already exists for index");
+
+        dxp->cookie = cookie;
+        dxp->ndescs = needed;
+
+        /* Enqueue buffer onto the ring. */
+        idx = vq_ring_add_buffer(vq, vq->vq_ring.desc, head_idx, buffer,        /*idx now "desc.next"*/
+                readable, writable);
+
+        vq->vq_desc_head_idx = idx;
+        vq->vq_free_cnt -= needed;
+
+        if (vq->vq_free_cnt == 0)
+            VQ_RING_ASSERT_CHAIN_TERM(vq);
+        else
+            VQ_RING_ASSERT_VALID_IDX(vq, idx);
+
+        /*
+         * Update vring_avail control block fields so that other
+         * side can get buffer using it.
+         */
+        vq_ring_update_avail(vq, head_idx);
+    }
+
+    VQUEUE_IDLE(vq);
+
+    return (status);
+}
+
+/**
+ * virtqueue_add_single_buffer - Enqueues single buffer in vring
+ *
+ * @param vq                    - Pointer to VirtIO queue control block
+ * @param cookie                - Pointer to hold call back data
+ * @param buffer_addr           - Address of buffer
+ * @param len                   - Length of buffer
+ * @param writable              - If buffer writable
+ * @param has_next              - If buffers for subsequent call are
+ *                                to be chained
+ *
+ * @return                      - Function status
+ */
+int virtqueue_add_single_buffer(struct virtqueue *vq, void *cookie,             /*this function is not used at all*/
+        void *buffer_addr, uint_t len, int writable, boolean has_next) {
+
+    struct vq_desc_extra *dxp;
+    struct vring_desc *dp;
+    uint16_t head_idx;
+    uint16_t idx;
+    int status = VQUEUE_SUCCESS;
+
+    VQ_PARAM_CHK(vq == VQ_NULL, status, ERROR_VQUEUE_INVLD_PARAM);
+    VQ_PARAM_CHK(vq->vq_free_cnt == 0, status, ERROR_VRING_FULL);
+
+    VQUEUE_BUSY(vq);
+
+    if (status == VQUEUE_SUCCESS) {
+
+        VQASSERT(vq, cookie != VQ_NULL, "enqueuing with no cookie");
+
+        head_idx = vq->vq_desc_head_idx;
+        dxp = &vq->vq_descx[head_idx];
+
+        dxp->cookie = cookie;
+        dxp->ndescs = 1;
+        idx = head_idx;
+
+        dp = &vq->vq_ring.desc[idx];
+        dp->addr = env_map_vatopa(buffer_addr);
+        dp->len = len;
+        dp->flags = 0;
+        idx = dp->next;
+
+        if (has_next)
+            dp->flags |= VRING_DESC_F_NEXT;
+        if (writable)
+            dp->flags |= VRING_DESC_F_WRITE;
+
+        vq->vq_desc_head_idx = idx;
+        vq->vq_free_cnt--;
+
+        if (vq->vq_free_cnt == 0)
+            VQ_RING_ASSERT_CHAIN_TERM(vq);
+        else
+            VQ_RING_ASSERT_VALID_IDX(vq, idx);
+
+        vq_ring_update_avail(vq, head_idx);
+    }
+
+    VQUEUE_IDLE(vq);
+
+    return (status);
+}
+
+/**
+ * virtqueue_get_buffer - Returns used buffers from VirtIO queue
+ *
+ * @param vq            - Pointer to VirtIO queue control block
+ * @param len           - Length of conumed buffer
+ *
+ * @return              - Pointer to used buffer
+ */
+void *virtqueue_get_buffer(struct virtqueue *vq, uint32_t *len) {
+    struct vring_used_elem *uep;
+    void *cookie;
+    uint16_t used_idx, desc_idx;
+
+    if ((vq == VQ_NULL) || (vq->vq_used_cons_idx == vq->vq_ring.used->idx))
+        return (VQ_NULL);
+
+    VQUEUE_BUSY(vq);
+
+    used_idx = vq->vq_used_cons_idx++ & (vq->vq_nentries - 1);
+    uep = &vq->vq_ring.used->ring[used_idx];
+
+    env_rmb();
+
+    desc_idx = (uint16_t) uep->id;
+    if (len != VQ_NULL)
+        *len = uep->len;
+
+    vq_ring_free_chain(vq, desc_idx);
+
+    cookie = vq->vq_descx[desc_idx].cookie;
+    vq->vq_descx[desc_idx].cookie = VQ_NULL;
+
+    VQUEUE_IDLE(vq);
+
+    return (cookie);
+}
+
+/**
+ * virtqueue_free   - Frees VirtIO queue resources
+ *
+ * @param vq        - Pointer to VirtIO queue control block
+ *
+ */
+void virtqueue_free(struct virtqueue *vq) {
+
+    if (vq != VQ_NULL) {
+
+        if (vq->vq_free_cnt != vq->vq_nentries) {
+            env_print("\r\nWARNING %s: freeing non-empty virtqueue\r\n", vq->vq_name);
+        }
+
+        //TODO : Need to free indirect buffers here
+
+        if (vq->vq_ring_mem != VQ_NULL) {
+            vq->vq_ring_size = 0;
+            vq->vq_ring_mem = VQ_NULL;
+        }
+
+        env_free_memory(vq);
+    }
+}
+
+/**
+ * virtqueue_get_available_buffer   - Returns buffer available for use in the
+ *                                    VirtIO queue
+ *
+ * @param vq                        - Pointer to VirtIO queue control block
+ * @param avail_idx                 - Pointer to index used in vring desc table
+ * @param len                       - Length of buffer
+ *
+ * @return                          - Pointer to available buffer
+ */
+void *virtqueue_get_available_buffer(struct virtqueue *vq, uint16_t *avail_idx,
+        uint32_t *len) {
+
+    uint16_t head_idx = 0;
+    void *buffer;
+
+    if (vq->vq_available_idx == vq->vq_ring.avail->idx) {       /*vq->vq_ring.avial->idx is updated in "rpmsg_rdev_create_virtqueues" "virtqueue_add_buffer" */
+        return (VQ_NULL);
+    }
+
+    VQUEUE_BUSY(vq);
+
+    head_idx = vq->vq_available_idx++ & (vq->vq_nentries - 1);
+    *avail_idx = vq->vq_ring.avail->ring[head_idx];
+
+    env_rmb();
+
+    buffer = env_map_patova(vq->vq_ring.desc[*avail_idx].addr);
+    *len = vq->vq_ring.desc[*avail_idx].len;
+
+    VQUEUE_IDLE(vq);
+
+    return (buffer);
+}
+
+/**
+ * virtqueue_add_consumed_buffer - Returns consumed buffer back to VirtIO queue
+ *
+ * @param vq                     - Pointer to VirtIO queue control block
+ * @param head_idx               - Index of vring desc containing used buffer
+ * @param len                    - Length of buffer
+ *
+ * @return                       - Function status
+ */
+int virtqueue_add_consumed_buffer(struct virtqueue *vq, uint16_t head_idx,
+        uint_t len) {
+
+    struct vring_used_elem *used_desc = VQ_NULL;
+    uint16_t used_idx;
+
+    if ((head_idx > vq->vq_nentries) || (head_idx < 0)) {
+        return (ERROR_VRING_NO_BUFF);
+    }
+
+    VQUEUE_BUSY(vq);
+
+    used_idx = vq->vq_ring.used->idx & (vq->vq_nentries - 1);
+    used_desc = &(vq->vq_ring.used->ring[used_idx]);
+    used_desc->id = head_idx;
+    used_desc->len = len;
+
+    env_wmb();
+
+    vq->vq_ring.used->idx++;
+
+    VQUEUE_IDLE(vq);
+
+    return (VQUEUE_SUCCESS);
+}
+
+/**
+ * virtqueue_enable_cb  - Enables callback generation
+ *
+ * @param vq            - Pointer to VirtIO queue control block
+ *
+ * @return              - Function status
+ */
+int virtqueue_enable_cb(struct virtqueue *vq) {
+
+    return (vq_ring_enable_interrupt(vq, 0));
+}
+
+/**
+ * virtqueue_enable_cb - Disables callback generation
+ *
+ * @param vq           - Pointer to VirtIO queue control block
+ *
+ */
+void virtqueue_disable_cb(struct virtqueue *vq) {
+
+    VQUEUE_BUSY(vq);
+
+    if (vq->vq_flags & VIRTQUEUE_FLAG_EVENT_IDX) {
+        vring_used_event(&vq->vq_ring)= vq->vq_used_cons_idx - vq->vq_nentries
+        - 1;
+    } else {
+        vq->vq_ring.avail->flags |= VRING_AVAIL_F_NO_INTERRUPT;
+    }
+
+    VQUEUE_IDLE(vq);
+}
+
+/**
+ * virtqueue_kick - Notifies other side that there is buffer available for it.
+ *
+ * @param vq      - Pointer to VirtIO queue control block
+ */
+void virtqueue_kick(struct virtqueue *vq) {
+
+    VQUEUE_BUSY(vq);
+
+    /* Ensure updated avail->idx is visible to host. */
+    env_mb();
+
+    if (vq_ring_must_notify_host(vq))
+        vq_ring_notify_host(vq);
+
+    vq->vq_queued_cnt = 0;
+
+    VQUEUE_IDLE(vq);
+}
+
+/**
+ * virtqueue_dump Dumps important virtqueue fields , use for debugging purposes
+ *
+ * @param vq - Pointer to VirtIO queue control block
+ */
+void virtqueue_dump(struct virtqueue *vq) {
+
+    if (vq == VQ_NULL)
+        return;
+
+    env_print("VQ: %s - size=%d; free=%d; used=%d; queued=%d; "
+            "desc_head_idx=%d; avail.idx=%d; used_cons_idx=%d; "
+            "used.idx=%d; avail.flags=0x%x; used.flags=0x%x\r\n", vq->vq_name,
+            vq->vq_nentries, vq->vq_free_cnt, virtqueue_nused(vq),
+            vq->vq_queued_cnt, vq->vq_desc_head_idx, vq->vq_ring.avail->idx,
+            vq->vq_used_cons_idx, vq->vq_ring.used->idx,
+            vq->vq_ring.avail->flags, vq->vq_ring.used->flags);
+}
+
+/**
+ * virtqueue_get_desc_size - Returns vring descriptor size
+ *
+ * @param vq            - Pointer to VirtIO queue control block
+ *
+ * @return              - Descriptor length
+ */
+uint32_t virtqueue_get_desc_size(struct virtqueue *vq) {
+    uint16_t head_idx = 0;
+    uint16_t avail_idx = 0;
+    uint32_t len = 0;
+
+    if (vq->vq_available_idx == vq->vq_ring.avail->idx) {
+        return (VQ_NULL);
+    }
+
+    VQUEUE_BUSY(vq);
+
+    head_idx = vq->vq_available_idx & (vq->vq_nentries - 1);
+    avail_idx = vq->vq_ring.avail->ring[head_idx];
+    len = vq->vq_ring.desc[avail_idx].len;
+
+    VQUEUE_IDLE(vq);
+
+    return (len);
+}
+/**************************************************************************
+ *                            Helper Functions                            *
+ **************************************************************************/
+
+/**
+ *
+ * vq_ring_add_buffer
+ *
+ */
+static uint16_t vq_ring_add_buffer(struct virtqueue *vq,
+        struct vring_desc *desc, uint16_t head_idx, struct llist *buffer,
+        int readable, int writable) {
+
+    struct vring_desc *dp;
+    int i, needed;
+    uint16_t idx;
+
+    needed = readable + writable;
+
+    for (i = 0, idx = head_idx; (i < needed && buffer != VQ_NULL);
+            i++, idx = dp->next, buffer = buffer->next) {
+
+        VQASSERT(vq, idx != VQ_RING_DESC_CHAIN_END,
+                "premature end of free desc chain");
+
+        dp = &desc[idx];
+        dp->addr = env_map_vatopa(buffer->data);
+        dp->len = buffer->attr;
+        dp->flags = 0;
+
+        if (i < needed - 1)
+            dp->flags |= VRING_DESC_F_NEXT;
+
+        /* Readable buffers are inserted into vring before the writable buffers.*/
+        if (i >= readable)
+            dp->flags |= VRING_DESC_F_WRITE;
+    }
+
+    return (idx);
+}
+
+/**
+ *
+ * vq_ring_free_chain
+ *
+ */
+static void vq_ring_free_chain(struct virtqueue *vq, uint16_t desc_idx) {
+    struct vring_desc *dp;
+    struct vq_desc_extra *dxp;
+
+    VQ_RING_ASSERT_VALID_IDX(vq, desc_idx);
+    dp = &vq->vq_ring.desc[desc_idx];
+    dxp = &vq->vq_descx[desc_idx];
+
+    if (vq->vq_free_cnt == 0)
+        VQ_RING_ASSERT_CHAIN_TERM(vq);
+
+    vq->vq_free_cnt += dxp->ndescs;
+    dxp->ndescs--;
+
+    if ((dp->flags & VRING_DESC_F_INDIRECT) == 0) {
+        while (dp->flags & VRING_DESC_F_NEXT) {
+            VQ_RING_ASSERT_VALID_IDX(vq, dp->next);
+            dp = &vq->vq_ring.desc[dp->next];
+            dxp->ndescs--;
+        }
+    }
+
+    VQASSERT(vq, (dxp->ndescs == 0),
+            "failed to free entire desc chain, remaining");
+
+    /*
+     * We must append the existing free chain, if any, to the end of
+     * newly freed chain. If the virtqueue was completely used, then
+     * head would be VQ_RING_DESC_CHAIN_END (ASSERTed above).
+     */
+    dp->next = vq->vq_desc_head_idx;
+    vq->vq_desc_head_idx = desc_idx;
+}
+
+/**
+ *
+ * vq_ring_init
+ *
+ */
+static void vq_ring_init(struct virtqueue *vq) {
+    struct vring *vr;
+    unsigned char *ring_mem;
+    int i, size;
+
+    ring_mem = vq->vq_ring_mem;
+    size = vq->vq_nentries;
+    vr = &vq->vq_ring;
+
+    vring_init(vr, size, ring_mem, vq->vq_alignment);
+
+    for (i = 0; i < size - 1; i++)
+        vr->desc[i].next = i + 1;
+    vr->desc[i].next = VQ_RING_DESC_CHAIN_END;
+}
+
+/**
+ *
+ * vq_ring_update_avail
+ *
+ */
+static void vq_ring_update_avail(struct virtqueue *vq, uint16_t desc_idx) {
+    uint16_t avail_idx;
+
+    /*
+     * Place the head of the descriptor chain into the next slot and make
+     * it usable to the host. The chain is made available now rather than
+     * deferring to virtqueue_notify() in the hopes that if the host is
+     * currently running on another CPU, we can keep it processing the new
+     * descriptor.
+     */
+    avail_idx = vq->vq_ring.avail->idx & (vq->vq_nentries - 1);
+    vq->vq_ring.avail->ring[avail_idx] = desc_idx;
+
+    env_wmb();
+
+    vq->vq_ring.avail->idx++;
+
+    /* Keep pending count until virtqueue_notify(). */
+    vq->vq_queued_cnt++;
+}
+
+/**
+ *
+ * vq_ring_enable_interrupt
+ *
+ */
+static int vq_ring_enable_interrupt(struct virtqueue *vq, uint16_t ndesc) {
+
+    /*
+     * Enable interrupts, making sure we get the latest index of
+     * what's already been consumed.
+     */
+    if (vq->vq_flags & VIRTQUEUE_FLAG_EVENT_IDX) {
+        vring_used_event(&vq->vq_ring)= vq->vq_used_cons_idx + ndesc;
+    } else {
+        vq->vq_ring.avail->flags &= ~VRING_AVAIL_F_NO_INTERRUPT;
+    }
+
+    env_mb();
+
+    /*
+     * Enough items may have already been consumed to meet our threshold
+     * since we last checked. Let our caller know so it processes the new
+     * entries.
+     */
+    if (virtqueue_nused(vq) > ndesc) {
+        return (1);
+    }
+
+    return (0);
+}
+
+/**
+ *
+ * virtqueue_interrupt
+ *
+ */
+void virtqueue_notification(struct virtqueue *vq) {
+
+    if (vq->callback != VQ_NULL)
+        vq->callback(vq);
+}
+
+/**
+ *
+ * vq_ring_must_notify_host
+ *
+ */
+static int vq_ring_must_notify_host(struct virtqueue *vq) {
+    uint16_t new_idx, prev_idx, event_idx;
+
+    if (vq->vq_flags & VIRTQUEUE_FLAG_EVENT_IDX) {
+        new_idx = vq->vq_ring.avail->idx;
+        prev_idx = new_idx - vq->vq_queued_cnt;
+        event_idx = vring_avail_event(&vq->vq_ring);
+
+        return (vring_need_event(event_idx, new_idx, prev_idx) != 0);
+    }
+
+    return ((vq->vq_ring.used->flags & VRING_USED_F_NO_NOTIFY) == 0);
+}
+
+/**
+ *
+ * vq_ring_notify_host
+ *
+ */
+static void vq_ring_notify_host(struct virtqueue *vq) {
+
+    if (vq->notify != VQ_NULL)
+        vq->notify(vq);     /*hil_vring_notify*/
+}
+
+/**
+ *
+ * virtqueue_nused
+ *
+ */
+static int virtqueue_nused(struct virtqueue *vq) {
+    uint16_t used_idx, nused;
+
+    used_idx = vq->vq_ring.used->idx;
+
+    nused = (uint16_t) (used_idx - vq->vq_used_cons_idx);
+    VQASSERT(vq, nused <= vq->vq_nentries, "used more than available");
+
+    return (nused);
+}
diff --git a/middleware/multicore/open-amp/virtio/virtqueue.h b/middleware/multicore/open-amp/virtio/virtqueue.h
new file mode 100644
index 0000000..4671f6e
--- /dev/null
+++ b/middleware/multicore/open-amp/virtio/virtqueue.h
@@ -0,0 +1,227 @@
+#ifndef VIRTQUEUE_H_
+#define VIRTQUEUE_H_
+
+/*-
+ * Copyright (c) 2011, Bryan Venteicher <bryanv@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice unmodified, this list of conditions, and the following
+ *    disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+#include <stdint.h>
+
+typedef         unsigned int                        uint_t;
+typedef         uint8_t                             boolean;
+
+#include "virtio_ring.h"
+#include "../porting/env/env.h"
+#include "../common/llist/llist.h"
+
+/*Error Codes*/
+#define VQ_ERROR_BASE                                 -3000
+#define ERROR_VRING_FULL                              (VQ_ERROR_BASE - 1)
+#define ERROR_INVLD_DESC_IDX                          (VQ_ERROR_BASE - 2)
+#define ERROR_EMPTY_RING                              (VQ_ERROR_BASE - 3)
+#define ERROR_NO_MEM                                  (VQ_ERROR_BASE - 4)
+#define ERROR_VRING_MAX_DESC                          (VQ_ERROR_BASE - 5)
+#define ERROR_VRING_ALIGN                             (VQ_ERROR_BASE - 6)
+#define ERROR_VRING_NO_BUFF                           (VQ_ERROR_BASE - 7)
+#define ERROR_VQUEUE_INVLD_PARAM                      (VQ_ERROR_BASE - 8)
+
+#define true                                          1
+#define false                                         0
+#define VQUEUE_SUCCESS                                0
+#define VQUEUE_DEBUG                                  false
+
+//TODO:
+/* This is temporary macro to replace C NULL support.
+ * At the moment all the RTL specific functions are present in env.
+ * */
+#define VQ_NULL                                       0
+
+/* The maximum virtqueue size is 2^15. Use that value as the end of
+ * descriptor chain terminator since it will never be a valid index
+ * in the descriptor table. This is used to verify we are correctly
+ * handling vq_free_cnt.
+ */
+#define VQ_RING_DESC_CHAIN_END                         32768
+#define VIRTQUEUE_FLAG_INDIRECT                        0x0001
+#define VIRTQUEUE_FLAG_EVENT_IDX                       0x0002
+#define VIRTQUEUE_MAX_NAME_SZ                          32
+
+/* Support for indirect buffer descriptors. */
+#define VIRTIO_RING_F_INDIRECT_DESC    (1 << 28)
+
+/* Support to suppress interrupt until specific index is reached. */
+#define VIRTIO_RING_F_EVENT_IDX        (1 << 29)
+
+/*
+ * Hint on how long the next interrupt should be postponed. This is
+ * only used when the EVENT_IDX feature is negotiated.
+ */
+typedef enum {
+    VQ_POSTPONE_SHORT,
+    VQ_POSTPONE_LONG,
+    VQ_POSTPONE_EMPTIED    /* Until all available desc are used. */
+} vq_postpone_t;
+
+struct virtqueue {
+    //TODO: Need to define proper structure for
+    //        virtio device with RPmsg and paravirtualization.
+
+    struct virtio_device *vq_dev;
+    char vq_name[VIRTQUEUE_MAX_NAME_SZ];
+    uint16_t vq_queue_index;
+    uint16_t vq_nentries;
+    uint32_t vq_flags;
+    int vq_alignment;
+    int vq_ring_size;       /*Seems not used at all*/
+    boolean vq_inuse;
+    void *vq_ring_mem;
+    void (*callback)(struct virtqueue *vq);
+    void (*notify)(struct virtqueue *vq);
+    int vq_max_indirect_size;
+    int vq_indirect_mem_size;
+    struct vring vq_ring;
+    uint16_t vq_free_cnt;
+    uint16_t vq_queued_cnt;
+
+    /*
+     * Head of the free chain in the descriptor table. If
+     * there are no free descriptors, this will be set to
+     * VQ_RING_DESC_CHAIN_END.
+     */
+    uint16_t vq_desc_head_idx;
+
+    /*
+     * Last consumed descriptor in the used table,
+     * trails vq_ring.used->idx.
+     */
+    uint16_t vq_used_cons_idx;
+
+    /*
+     * Last consumed descriptor in the available table -
+     * used by the consumer side.
+     */
+    uint16_t vq_available_idx;
+
+    uint8_t padd;
+
+    /*
+     * Used by the host side during callback. Cookie
+     * holds the address of buffer received from other side.
+     * Other fields in this structure are not used currently.
+     */
+
+    struct vq_desc_extra {
+        void *cookie;
+        struct vring_desc *indirect;
+        uint32_t indirect_paddr;
+        uint16_t ndescs;
+    } vq_descx[0];
+};
+
+/* struct to hold vring specific information */
+struct vring_alloc_info {
+    void         *phy_addr;
+    uint32_t     align;
+    uint16_t     num_descs;
+    uint16_t     pad;
+};
+
+typedef void   vq_callback(struct virtqueue *);
+typedef void   vq_notify(struct virtqueue *);
+
+#if (VQUEUE_DEBUG == true)
+
+#define VQASSERT(_vq, _exp, _msg) do{ \
+    if (!(_exp)){ env_print("%s: %s - "_msg, __func__, (_vq)->vq_name); while(1);} \
+    } while(0)
+
+#define VQ_RING_ASSERT_VALID_IDX(_vq, _idx)            \
+    VQASSERT((_vq), (_idx) < (_vq)->vq_nentries,        \
+    "invalid ring index")
+
+#define VQ_RING_ASSERT_CHAIN_TERM(_vq)                \
+    VQASSERT((_vq), (_vq)->vq_desc_head_idx ==            \
+    VQ_RING_DESC_CHAIN_END,    "full ring terminated incorrectly: invalid head")
+
+#define VQ_PARAM_CHK(condition, status_var, status_err)                 \
+                       if ((status_var == 0) && (condition))            \
+                       {                                                \
+                           status_var = status_err;                     \
+                       }
+
+#define VQUEUE_BUSY(vq)         if ((vq)->vq_inuse == false)                 \
+                                    (vq)->vq_inuse = true;                   \
+                                else                                         \
+                                    VQASSERT(vq, (vq)->vq_inuse == false,    \
+                                        "VirtQueue already in use")
+
+#define VQUEUE_IDLE(vq)            ((vq)->vq_inuse = false)
+
+#else
+
+#define KASSERT(cond, str)
+#define VQASSERT(_vq, _exp, _msg)
+#define VQ_RING_ASSERT_VALID_IDX(_vq, _idx)
+#define VQ_RING_ASSERT_CHAIN_TERM(_vq)
+#define VQ_PARAM_CHK(condition, status_var, status_err)
+#define VQUEUE_BUSY(vq)
+#define VQUEUE_IDLE(vq)
+
+#endif
+
+int virtqueue_create(struct virtio_device *device, unsigned short id, char *name,
+        struct vring_alloc_info *ring, void (*callback)(struct virtqueue *vq),
+        void (*notify)(struct virtqueue *vq), struct virtqueue **v_queue);
+
+int virtqueue_add_buffer(struct virtqueue *vq, struct llist *buffer,
+        int readable, int writable, void *cookie);
+
+int virtqueue_add_single_buffer(struct virtqueue *vq, void *cookie,
+        void* buffer_addr, uint_t len, int writable, boolean has_next);
+
+void *virtqueue_get_buffer(struct virtqueue *vq, uint32_t *len);
+
+void *virtqueue_get_available_buffer(struct virtqueue *vq, uint16_t *avail_idx,
+        uint32_t *len);
+
+int virtqueue_add_consumed_buffer(struct virtqueue *vq, uint16_t head_idx,
+        uint_t len);
+
+void virtqueue_disable_cb(struct virtqueue *vq);
+
+int virtqueue_enable_cb(struct virtqueue *vq);
+
+void virtqueue_kick(struct virtqueue *vq);
+
+void virtqueue_free(struct virtqueue *vq);
+
+void virtqueue_dump(struct virtqueue *vq);
+
+void virtqueue_notification(struct virtqueue *vq);
+
+uint32_t virtqueue_get_desc_size(struct virtqueue *vq);
+
+#endif /* VIRTQUEUE_H_ */