This sample driver creates mdev device that simulate virtio net device
over virtio mdev transport. The device is implemented through vringh
and workqueue.

Signed-off-by: Jason Wang <jasow...@redhat.com>
---
 samples/Kconfig            |   7 +
 samples/vfio-mdev/Makefile |   1 +
 samples/vfio-mdev/mvnet.c  | 766 +++++++++++++++++++++++++++++++++++++
 3 files changed, 774 insertions(+)
 create mode 100644 samples/vfio-mdev/mvnet.c

diff --git a/samples/Kconfig b/samples/Kconfig
index c8dacb4dda80..a1a1ca2c00b7 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -131,6 +131,13 @@ config SAMPLE_VFIO_MDEV_MDPY
          mediated device.  It is a simple framebuffer and supports
          the region display interface (VFIO_GFX_PLANE_TYPE_REGION).
 
+config SAMPLE_VIRTIO_MDEV_NET
+        tristate "Build virtio mdev net example mediated device sample code -- 
loadable modules only"
+       depends on VIRTIO_MDEV_DEVICE && VHOST_RING && m
+       help
+         Build a networking sample device for use as a virtio
+         mediated device.
+
 config SAMPLE_VFIO_MDEV_MDPY_FB
        tristate "Build VFIO mdpy example guest fbdev driver -- loadable module 
only"
        depends on FB && m
diff --git a/samples/vfio-mdev/Makefile b/samples/vfio-mdev/Makefile
index 10d179c4fdeb..f34af90ed0a0 100644
--- a/samples/vfio-mdev/Makefile
+++ b/samples/vfio-mdev/Makefile
@@ -3,3 +3,4 @@ obj-$(CONFIG_SAMPLE_VFIO_MDEV_MTTY) += mtty.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY) += mdpy.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MDPY_FB) += mdpy-fb.o
 obj-$(CONFIG_SAMPLE_VFIO_MDEV_MBOCHS) += mbochs.o
+obj-$(CONFIG_SAMPLE_VIRTIO_MDEV_NET) += mvnet.o
diff --git a/samples/vfio-mdev/mvnet.c b/samples/vfio-mdev/mvnet.c
new file mode 100644
index 000000000000..da295b41955e
--- /dev/null
+++ b/samples/vfio-mdev/mvnet.c
@@ -0,0 +1,766 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Mediated virtual virtio-net device driver.
+ *
+ * Copyright (c) 2019, Red Hat Inc. All rights reserved.
+ *     Author: Jason Wang <jasow...@redhat.com>
+ *
+ * Sample driver that creates mdev device that simulates ethernet
+ * device virtio mdev transport.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+#include <linux/uuid.h>
+#include <linux/iommu.h>
+#include <linux/sysfs.h>
+#include <linux/file.h>
+#include <linux/etherdevice.h>
+#include <linux/mdev.h>
+#include <uapi/linux/virtio_mdev.h>
+
+#define VERSION_STRING  "0.1"
+#define DRIVER_AUTHOR   "NVIDIA Corporation"
+
+#define MVNET_CLASS_NAME "mvnet"
+
+#define MVNET_NAME       "mvnet"
+
+/*
+ * Global Structures
+ */
+
+static struct mvnet_dev {
+       struct class    *vd_class;
+       struct idr      vd_idr;
+       struct device   dev;
+} mvnet_dev;
+
+struct mvnet_virtqueue {
+       struct vringh vring;
+       struct vringh_kiov iov;
+       unsigned short head;
+       bool ready;
+       u32 desc_addr_lo;
+       u32 desc_addr_hi;
+       u32 device_addr_lo;
+       u32 device_addr_hi;
+       u32 driver_addr_lo;
+       u32 driver_addr_hi;
+       u64 desc_addr;
+       u64 device_addr;
+       u64 driver_addr;
+       void *private;
+       irqreturn_t (*cb)(void *);
+};
+
+#define MVNET_QUEUE_ALIGN PAGE_SIZE
+#define MVNET_QUEUE_MAX 256
+#define MVNET_MAGIC_VALUE ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)
+#define MVNET_VERSION 0x1 /* Implies virtio 1.0 */
+#define MVNET_DEVICE_ID 0x1 /* network card */
+#define MVNET_VENDOR_ID 0 /* is this correct ? */
+#define MVNET_DEVICE_FEATURES VIRTIO_F_VERSION_1
+
+u64 mvnet_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
+                    (1ULL << VIRTIO_F_VERSION_1) |
+                    (1ULL << VIRTIO_F_IOMMU_PLATFORM) ;
+
+/* State of each mdev device */
+struct mvnet_state {
+       struct mvnet_virtqueue vqs[2];
+       struct work_struct work;
+       spinlock_t lock;
+       struct mdev_device *mdev;
+       struct virtio_net_config config;
+       struct virtio_mdev_callback *cbs;
+       void *buffer;
+       u32 queue_sel;
+       u32 driver_features_sel;
+       u32 driver_features[2];
+       u32 device_features_sel;
+       u32 status;
+       u32 generation;
+       u32 num;
+       struct list_head next;
+};
+
+static struct mutex mdev_list_lock;
+static struct list_head mdev_devices_list;
+
+static void mvnet_queue_ready(struct mvnet_state *mvnet, unsigned idx)
+{
+       struct mvnet_virtqueue *vq = &mvnet->vqs[idx];
+       int ret;
+
+       vq->desc_addr = (u64)vq->desc_addr_hi << 32 | vq->desc_addr_lo;
+       vq->device_addr = (u64)vq->device_addr_hi << 32 | vq->device_addr_lo;
+       vq->driver_addr = (u64)vq->driver_addr_hi << 32 | vq->driver_addr_lo;
+
+       ret = vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
+                              false, (struct vring_desc *)vq->desc_addr,
+                              (struct vring_avail *)vq->driver_addr,
+                              (struct vring_used *)vq->device_addr);
+}
+
+static ssize_t mvnet_read_config(struct mdev_device *mdev,
+                                u32 *val, loff_t pos)
+{
+       struct mvnet_state *mvnet;
+       struct mvnet_virtqueue *vq;
+       u32 queue_sel;
+
+       if (!mdev || !val)
+               return -EINVAL;
+
+       mvnet = mdev_get_drvdata(mdev);
+       if (!mvnet) {
+               pr_err("%s mvnet not found\n", __func__);
+               return -EINVAL;
+       }
+
+       queue_sel = mvnet->queue_sel;
+       vq = &mvnet->vqs[queue_sel];
+
+       switch (pos) {
+       case VIRTIO_MDEV_MAGIC_VALUE:
+               *val = MVNET_MAGIC_VALUE;
+               break;
+       case VIRTIO_MDEV_VERSION:
+               *val = MVNET_VERSION;
+               break;
+       case VIRTIO_MDEV_DEVICE_ID:
+               *val = MVNET_DEVICE_ID;
+               break;
+       case VIRTIO_MDEV_VENDOR_ID:
+               *val = MVNET_VENDOR_ID;
+               break;
+       case VIRTIO_MDEV_DEVICE_FEATURES:
+               if (mvnet->device_features_sel)
+                       *val = mvnet_features >> 32;
+               else
+                       *val = mvnet_features;
+               break;
+       case VIRTIO_MDEV_QUEUE_NUM_MAX:
+               *val = MVNET_QUEUE_MAX;
+               break;
+       case VIRTIO_MDEV_QUEUE_READY:
+               *val = vq->ready;
+               break;
+       case VIRTIO_MDEV_QUEUE_ALIGN:
+               *val = MVNET_QUEUE_ALIGN;
+               break;
+       case VIRTIO_MDEV_STATUS:
+               *val = mvnet->status;
+               break;
+       case VIRTIO_MDEV_QUEUE_DESC_LOW:
+               *val = vq->desc_addr_lo;
+               break;
+       case VIRTIO_MDEV_QUEUE_DESC_HIGH:
+               *val = vq->desc_addr_hi;
+               break;
+       case VIRTIO_MDEV_QUEUE_AVAIL_LOW:
+               *val = vq->driver_addr_lo;
+               break;
+       case VIRTIO_MDEV_QUEUE_AVAIL_HIGH:
+               *val = vq->driver_addr_hi;
+               break;
+       case VIRTIO_MDEV_QUEUE_USED_LOW:
+               *val = vq->device_addr_lo;
+               break;
+       case VIRTIO_MDEV_QUEUE_USED_HIGH:
+               *val = vq->device_addr_hi;
+               break;
+       case VIRTIO_MDEV_CONFIG_GENERATION:
+               *val = 1;
+               break;
+       default:
+               pr_err("Unsupported mdev read offset at 0x%x\n", pos);
+               break;
+       }
+
+       return 4;
+}
+
+static ssize_t mvnet_read_net_config(struct mdev_device *mdev,
+                                    char *buf, size_t count, loff_t pos)
+{
+       struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+
+       if (!mvnet) {
+               pr_err("%s mvnet not found\n", __func__);
+               return -EINVAL;
+       }
+
+       if (pos + count > sizeof(mvnet->config))
+               return -EINVAL;
+
+       memcpy(buf, &mvnet->config + (unsigned)pos, count);
+
+       return count;
+}
+
+static void mvnet_vq_reset(struct mvnet_virtqueue *vq)
+{
+       vq->ready = 0;
+       vq->desc_addr_lo = vq->desc_addr_hi = 0;
+       vq->device_addr_lo = vq->device_addr_hi = 0;
+       vq->driver_addr_lo = vq->driver_addr_hi = 0;
+       vq->desc_addr = 0;
+       vq->driver_addr = 0;
+       vq->device_addr = 0;
+       vringh_init_kern(&vq->vring, mvnet_features, MVNET_QUEUE_MAX,
+                       false, 0, 0, 0);
+}
+
+static void mvnet_reset(struct mvnet_state *mvnet)
+{
+       int i;
+
+       for (i = 0; i < 2; i++)
+               mvnet_vq_reset(&mvnet->vqs[i]);
+
+       mvnet->queue_sel = 0;
+       mvnet->driver_features_sel = 0;
+       mvnet->device_features_sel = 0;
+       mvnet->status = 0;
+       ++mvnet->generation;
+}
+
+static ssize_t mvnet_write_config(struct mdev_device *mdev,
+                                 u32 *val, loff_t pos)
+{
+       struct mvnet_state *mvnet;
+       struct mvnet_virtqueue *vq;
+       u32 queue_sel;
+
+       if (!mdev || !val)
+               return -EINVAL;
+
+       mvnet = mdev_get_drvdata(mdev);
+       if (!mvnet) {
+               pr_err("%s mvnet not found\n", __func__);
+               return -EINVAL;
+       }
+
+       queue_sel = mvnet->queue_sel;
+       vq = &mvnet->vqs[queue_sel];
+
+       switch (pos) {
+       case VIRTIO_MDEV_DEVICE_FEATURES_SEL:
+               mvnet->device_features_sel = *val;
+               break;
+       case VIRTIO_MDEV_DRIVER_FEATURES:
+               mvnet->driver_features[mvnet->driver_features_sel] = *val;
+               break;
+       case VIRTIO_MDEV_DRIVER_FEATURES_SEL:
+               mvnet->driver_features_sel = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_SEL:
+               mvnet->queue_sel = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_NUM:
+               mvnet->num = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_READY:
+               vq->ready = *val;
+               if (vq->ready) {
+                       spin_lock(&mvnet->lock);
+                       mvnet_queue_ready(mvnet, queue_sel);
+                       spin_unlock(&mvnet->lock);
+               }
+               break;
+       case VIRTIO_MDEV_QUEUE_NOTIFY:
+               if (vq->ready)
+                       schedule_work(&mvnet->work);
+               break;
+       case VIRTIO_MDEV_STATUS:
+               mvnet->status = *val;
+               if (*val == 0) {
+                       spin_lock(&mvnet->lock);
+                       mvnet_reset(mvnet);
+                       spin_unlock(&mvnet->lock);
+               }
+               break;
+       case VIRTIO_MDEV_QUEUE_DESC_LOW:
+               vq->desc_addr_lo = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_DESC_HIGH:
+               vq->desc_addr_hi = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_AVAIL_LOW:
+               vq->driver_addr_lo = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_AVAIL_HIGH:
+               vq->driver_addr_hi = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_USED_LOW:
+               vq->device_addr_lo = *val;
+               break;
+       case VIRTIO_MDEV_QUEUE_USED_HIGH:
+               vq->device_addr_hi = *val;
+               break;
+       default:
+               pr_err("Unsupported write offset! 0x%x\n", pos);
+               break;
+       }
+       spin_unlock(&mvnet->lock);
+
+       return 4;
+}
+
+static void mvnet_work(struct work_struct *work)
+{
+       struct mvnet_state *mvnet = container_of(work, struct
+                                                mvnet_state, work);
+       struct mvnet_virtqueue *txq = &mvnet->vqs[1];
+       struct mvnet_virtqueue *rxq = &mvnet->vqs[0];
+       size_t read, write, total_write;
+       unsigned long flags;
+       int err;
+       int pkts = 0;
+
+       spin_lock(&mvnet->lock);
+
+       if (!txq->ready || !rxq->ready)
+               goto out;
+
+       while (true) {
+               total_write = 0;
+               err = vringh_getdesc_kern(&txq->vring, &txq->iov, NULL,
+                                         &txq->head, GFP_KERNEL);
+               if (err <= 0)
+                       break;
+
+               err = vringh_getdesc_kern(&rxq->vring, NULL, &rxq->iov,
+                                         &rxq->head, GFP_KERNEL);
+               if (err <= 0) {
+                       vringh_complete_kern(&txq->vring, txq->head, 0);
+                       break;
+               }
+
+               while (true) {
+                       read = vringh_iov_pull_kern(&txq->iov, mvnet->buffer,
+                                                   PAGE_SIZE);
+                       if (read <= 0)
+                               break;
+
+                       write = vringh_iov_push_kern(&rxq->iov, mvnet->buffer,
+                                                    read);
+                       if (write <= 0)
+                               break;
+
+                       total_write += write;
+               }
+
+               /* Make sure data is wrote before advancing index */
+               smp_wmb();
+
+               vringh_complete_kern(&txq->vring, txq->head, 0);
+               vringh_complete_kern(&rxq->vring, rxq->head, total_write);
+
+               /* Make sure used is visible before rasing the
+                  interrupt */
+               smp_wmb();
+
+               local_bh_disable();
+               if (txq->cb)
+                       txq->cb(txq->private);
+               if (rxq->cb)
+                       rxq->cb(rxq->private);
+               local_bh_enable();
+
+               pkts ++;
+               if (pkts > 4) {
+                       schedule_work(&mvnet->work);
+                       goto out;
+               }
+       }
+
+out:
+       spin_unlock(&mvnet->lock);
+}
+
+static dma_addr_t mvnet_map_page(struct device *dev, struct page *page,
+                                unsigned long offset, size_t size,
+                                enum dma_data_direction dir,
+                                unsigned long attrs)
+{
+       /* Vringh can only use VA */
+       return page_address(page) + offset;
+}
+
+static void mvnet_unmap_page(struct device *dev, dma_addr_t dma_addr,
+                            size_t size, enum dma_data_direction dir,
+                            unsigned long attrs)
+{
+       return ;
+}
+
+static void *mvnet_alloc_coherent(struct device *dev, size_t size,
+                                 dma_addr_t *dma_addr, gfp_t flag,
+                                 unsigned long attrs)
+{
+       void *ret = kmalloc(size, flag);
+
+       if (ret == NULL)
+               *dma_addr = DMA_MAPPING_ERROR;
+       else
+               *dma_addr = ret;
+
+       return ret;
+}
+
+static void mvnet_free_coherent(struct device *dev, size_t size,
+                               void *vaddr, dma_addr_t dma_addr,
+                               unsigned long attrs)
+{
+       kfree(dma_addr);
+}
+
+static const struct dma_map_ops mvnet_dma_ops = {
+       .map_page = mvnet_map_page,
+       .unmap_page = mvnet_unmap_page,
+       .alloc = mvnet_alloc_coherent,
+       .free = mvnet_free_coherent,
+};
+
+static int mvnet_create(struct kobject *kobj, struct mdev_device *mdev)
+{
+       struct mvnet_state *mvnet;
+       struct virtio_net_config *config;
+
+       if (!mdev)
+               return -EINVAL;
+
+       mvnet = kzalloc(sizeof(struct mvnet_state), GFP_KERNEL);
+       if (mvnet == NULL)
+               return -ENOMEM;
+
+       mvnet->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
+       if (!mvnet->buffer) {
+               kfree(mvnet);
+               return -ENOMEM;
+       }
+
+       config = &mvnet->config;
+       config->mtu = 1500;
+       config->status = VIRTIO_NET_S_LINK_UP;
+       eth_random_addr(config->mac);
+
+       INIT_WORK(&mvnet->work, mvnet_work);
+
+       spin_lock_init(&mvnet->lock);
+       mvnet->mdev = mdev;
+       mdev_set_drvdata(mdev, mvnet);
+
+       mutex_lock(&mdev_list_lock);
+       list_add(&mvnet->next, &mdev_devices_list);
+       mutex_unlock(&mdev_list_lock);
+
+       mdev_set_dma_ops(mdev, &mvnet_dma_ops);
+
+       return 0;
+}
+
+static int mvnet_remove(struct mdev_device *mdev)
+{
+       struct mvnet_state *mds, *tmp_mds;
+       struct mvnet_state *mvnet = mdev_get_drvdata(mdev);
+       int ret = -EINVAL;
+
+       mutex_lock(&mdev_list_lock);
+       list_for_each_entry_safe(mds, tmp_mds, &mdev_devices_list, next) {
+               if (mvnet == mds) {
+                       list_del(&mvnet->next);
+                       mdev_set_drvdata(mdev, NULL);
+                       kfree(mvnet->buffer);
+                       kfree(mvnet);
+                       ret = 0;
+                       break;
+               }
+       }
+       mutex_unlock(&mdev_list_lock);
+
+       return ret;
+}
+
+static ssize_t mvnet_read(struct mdev_device *mdev, char __user *buf,
+                         size_t count, loff_t *ppos)
+{
+       ssize_t ret;
+
+       if (*ppos < VIRTIO_MDEV_CONFIG) {
+               if (count == 4)
+                       ret = mvnet_read_config(mdev, (u32 *)buf, *ppos);
+               else
+                       ret = -EINVAL;
+               *ppos += 4;
+       } else if (*ppos < VIRTIO_MDEV_CONFIG + sizeof(struct 
virtio_net_config)) {
+               ret = mvnet_read_net_config(mdev, buf, count,
+                                           *ppos - VIRTIO_MDEV_CONFIG);
+               *ppos += count;
+       } else {
+               ret = -EINVAL;
+       }
+
+       return ret;
+}
+
+static ssize_t mvnet_write(struct mdev_device *mdev, const char __user *buf,
+                          size_t count, loff_t *ppos)
+{
+       int ret;
+
+       if (*ppos < VIRTIO_MDEV_CONFIG) {
+               if (count == 4)
+                       ret = mvnet_write_config(mdev, (u32 *)buf, *ppos);
+               else
+                       ret = -EINVAL;
+               *ppos += 4;
+       } else {
+               /* No writable net config */
+               ret = -EINVAL;
+       }
+
+       return ret;
+}
+
+static long mvnet_ioctl(struct mdev_device *mdev, unsigned int cmd,
+                       unsigned long arg)
+{
+       int ret = 0;
+       struct mvnet_state *mvnet;
+       struct virtio_mdev_callback *cb;
+
+       if (!mdev)
+               return -EINVAL;
+
+       mvnet = mdev_get_drvdata(mdev);
+       if (!mvnet)
+               return -ENODEV;
+
+       spin_lock(&mvnet->lock);
+
+       switch (cmd) {
+       case VIRTIO_MDEV_SET_VQ_CALLBACK:
+               cb = (struct virtio_mdev_callback *)arg;
+               mvnet->vqs[mvnet->queue_sel].cb = cb->callback;
+               mvnet->vqs[mvnet->queue_sel].private = cb->private;
+               break;
+       case VIRTIO_MDEV_SET_CONFIG_CALLBACK:
+               break;
+       default:
+               pr_err("Not supportted ioctl cmd 0x%x\n", cmd);
+               ret = -ENOTTY;
+               break;
+       }
+
+       spin_unlock(&mvnet->lock);
+
+       return ret;
+}
+
+static int mvnet_open(struct mdev_device *mdev)
+{
+       pr_info("%s\n", __func__);
+       return 0;
+}
+
+static void mvnet_close(struct mdev_device *mdev)
+{
+       pr_info("%s\n", __func__);
+}
+
+static ssize_t
+sample_mvnet_dev_show(struct device *dev, struct device_attribute *attr,
+                    char *buf)
+{
+       return sprintf(buf, "This is phy device\n");
+}
+
+static DEVICE_ATTR_RO(sample_mvnet_dev);
+
+static struct attribute *mvnet_dev_attrs[] = {
+       &dev_attr_sample_mvnet_dev.attr,
+       NULL,
+};
+
+static const struct attribute_group mvnet_dev_group = {
+       .name  = "mvnet_dev",
+       .attrs = mvnet_dev_attrs,
+};
+
+static const struct attribute_group *mvnet_dev_groups[] = {
+       &mvnet_dev_group,
+       NULL,
+};
+
+static ssize_t
+sample_mdev_dev_show(struct device *dev, struct device_attribute *attr,
+                    char *buf)
+{
+       if (mdev_from_dev(dev))
+               return sprintf(buf, "This is MDEV %s\n", dev_name(dev));
+
+       return sprintf(buf, "\n");
+}
+
+static DEVICE_ATTR_RO(sample_mdev_dev);
+
+static struct attribute *mdev_dev_attrs[] = {
+       &dev_attr_sample_mdev_dev.attr,
+       NULL,
+};
+
+static const struct attribute_group mdev_dev_group = {
+       .name  = "vendor",
+       .attrs = mdev_dev_attrs,
+};
+
+static const struct attribute_group *mdev_dev_groups[] = {
+       &mdev_dev_group,
+       NULL,
+};
+
+#define MVNET_STRING_LEN 16
+
+static ssize_t
+name_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+       char name[MVNET_STRING_LEN];
+       const char *name_str = "virtio-net";
+
+       snprintf(name, MVNET_STRING_LEN, "%s", dev_driver_string(dev));
+       if (!strcmp(kobj->name, name))
+               return sprintf(buf, "%s\n", name_str);
+
+       return -EINVAL;
+}
+
+static MDEV_TYPE_ATTR_RO(name);
+
+static ssize_t
+available_instances_show(struct kobject *kobj, struct device *dev, char *buf)
+{
+       return sprintf(buf, "%d\n", INT_MAX);
+}
+
+static MDEV_TYPE_ATTR_RO(available_instances);
+
+static ssize_t device_api_show(struct kobject *kobj, struct device *dev,
+                              char *buf)
+{
+       return sprintf(buf, "%s\n", VIRTIO_MDEV_DEVICE_API_STRING);
+}
+
+static MDEV_TYPE_ATTR_RO(device_api);
+
+static struct attribute *mdev_types_attrs[] = {
+       &mdev_type_attr_name.attr,
+       &mdev_type_attr_device_api.attr,
+       &mdev_type_attr_available_instances.attr,
+       NULL,
+};
+
+static struct attribute_group mdev_type_group = {
+       .name  = "",
+       .attrs = mdev_types_attrs,
+};
+
+static struct attribute_group *mdev_type_groups[] = {
+       &mdev_type_group,
+       NULL,
+};
+
+static const struct mdev_parent_ops mdev_fops = {
+       .owner                  = THIS_MODULE,
+       .dev_attr_groups        = mvnet_dev_groups,
+       .mdev_attr_groups       = mdev_dev_groups,
+       .supported_type_groups  = mdev_type_groups,
+       .create                 = mvnet_create,
+       .remove                 = mvnet_remove,
+       .open                   = mvnet_open,
+       .release                = mvnet_close,
+       .read                   = mvnet_read,
+       .write                  = mvnet_write,
+       .ioctl                  = mvnet_ioctl,
+};
+
+static void mvnet_device_release(struct device *dev)
+{
+       dev_dbg(dev, "mvnet: released\n");
+}
+
+static int __init mvnet_dev_init(void)
+{
+       int ret = 0;
+
+       pr_info("mvnet_dev: %s\n", __func__);
+
+       memset(&mvnet_dev, 0, sizeof(mvnet_dev));
+
+       idr_init(&mvnet_dev.vd_idr);
+
+       mvnet_dev.vd_class = class_create(THIS_MODULE, MVNET_CLASS_NAME);
+
+       if (IS_ERR(mvnet_dev.vd_class)) {
+               pr_err("Error: failed to register mvnet_dev class\n");
+               ret = PTR_ERR(mvnet_dev.vd_class);
+               goto failed1;
+       }
+
+       mvnet_dev.dev.class = mvnet_dev.vd_class;
+       mvnet_dev.dev.release = mvnet_device_release;
+       dev_set_name(&mvnet_dev.dev, "%s", MVNET_NAME);
+
+       ret = device_register(&mvnet_dev.dev);
+       if (ret)
+               goto failed2;
+
+       ret = mdev_register_device(&mvnet_dev.dev, &mdev_fops);
+       if (ret)
+               goto failed3;
+
+       mutex_init(&mdev_list_lock);
+       INIT_LIST_HEAD(&mdev_devices_list);
+
+       goto all_done;
+
+failed3:
+
+       device_unregister(&mvnet_dev.dev);
+failed2:
+       class_destroy(mvnet_dev.vd_class);
+
+failed1:
+all_done:
+       return ret;
+}
+
+static void __exit mvnet_dev_exit(void)
+{
+       mvnet_dev.dev.bus = NULL;
+       mdev_unregister_device(&mvnet_dev.dev);
+
+       device_unregister(&mvnet_dev.dev);
+       idr_destroy(&mvnet_dev.vd_idr);
+       class_destroy(mvnet_dev.vd_class);
+       mvnet_dev.vd_class = NULL;
+       pr_info("mvnet_dev: Unloaded!\n");
+}
+
+module_init(mvnet_dev_init)
+module_exit(mvnet_dev_exit)
+
+MODULE_LICENSE("GPL v2");
+MODULE_INFO(supported, "Test driver that simulate serial port over PCI");
+MODULE_VERSION(VERSION_STRING);
+MODULE_AUTHOR(DRIVER_AUTHOR);
-- 
2.19.1

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