[PATCH char-misc-next 6/8] misc: mic: Enable VOP card side functionality

[Sudeep Dutt]

From: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>

This patch moves virtio functionality from the MIC card driver into a
separate hardware independent Virtio Over PCIe (VOP) driver. This
functionality was introduced in commit 2141c7c5ee67 ("Intel MIC Card
Driver Changes for Virtio Devices.") in
drivers/misc/mic/card/mic_virtio.c. Apart from being moved into a
separate driver the functionality is essentially unchanged. See the
above mentioned commit for a description of this functionality.

Signed-off-by: Sudeep Dutt <sudeep.dutt@xxxxxxxxx>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>
---
 drivers/misc/mic/vop/vop_main.c | 755 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 755 insertions(+)
 create mode 100644 drivers/misc/mic/vop/vop_main.c

diff --git a/drivers/misc/mic/vop/vop_main.c b/drivers/misc/mic/vop/vop_main.c
new file mode 100644
index 0000000..c86aeeb
--- /dev/null
+++ b/drivers/misc/mic/vop/vop_main.c
@@ -0,0 +1,755 @@
+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2016 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * The full GNU General Public License is included in this distribution in
+ * the file called "COPYING".
+ *
+ * Adapted from:
+ *
+ * virtio for kvm on s390
+ *
+ * Copyright IBM Corp. 2008
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2 only)
+ * as published by the Free Software Foundation.
+ *
+ *    Author(s): Christian Borntraeger <borntraeger@xxxxxxxxxx>
+ *
+ * Intel Virtio Over PCIe (VOP) driver.
+ *
+ */
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/dma-mapping.h>
+
+#include "vop_main.h"
+
+#define VOP_MAX_VRINGS 4
+
+/*
+ * _vop_vdev - Allocated per virtio device instance injected by the peer.
+ *
+ * @vdev: Virtio device
+ * @desc: Virtio device page descriptor
+ * @dc: Virtio device control
+ * @vpdev: VOP device which is the parent for this virtio device
+ * @vr: Buffer for accessing the VRING
+ * @used: Buffer for used
+ * @used_size: Size of the used buffer
+ * @reset_done: Track whether VOP reset is complete
+ * @virtio_cookie: Cookie returned upon requesting a interrupt
+ * @c2h_vdev_db: The doorbell used by the guest to interrupt the host
+ * @h2c_vdev_db: The doorbell used by the host to interrupt the guest
+ * @dnode: The destination node
+ */
+struct _vop_vdev {
+	struct virtio_device vdev;
+	struct mic_device_desc __iomem *desc;
+	struct mic_device_ctrl __iomem *dc;
+	struct vop_device *vpdev;
+	void __iomem *vr[VOP_MAX_VRINGS];
+	dma_addr_t used[VOP_MAX_VRINGS];
+	int used_size[VOP_MAX_VRINGS];
+	struct completion reset_done;
+	struct mic_irq *virtio_cookie;
+	int c2h_vdev_db;
+	int h2c_vdev_db;
+	int dnode;
+};
+
+#define to_vopvdev(vd) container_of(vd, struct _vop_vdev, vdev)
+
+#define _vop_aligned_desc_size(d) __mic_align(_vop_desc_size(d), 8)
+
+/* Helper API to obtain the parent of the virtio device */
+static inline struct device *_vop_dev(struct _vop_vdev *vdev)
+{
+	return vdev->vdev.dev.parent;
+}
+
+static inline unsigned _vop_desc_size(struct mic_device_desc __iomem *desc)
+{
+	return sizeof(*desc)
+		+ ioread8(&desc->num_vq) * sizeof(struct mic_vqconfig)
+		+ ioread8(&desc->feature_len) * 2
+		+ ioread8(&desc->config_len);
+}
+
+static inline struct mic_vqconfig __iomem *
+_vop_vq_config(struct mic_device_desc __iomem *desc)
+{
+	return (struct mic_vqconfig __iomem *)(desc + 1);
+}
+
+static inline u8 __iomem *
+_vop_vq_features(struct mic_device_desc __iomem *desc)
+{
+	return (u8 __iomem *)(_vop_vq_config(desc) + ioread8(&desc->num_vq));
+}
+
+static inline u8 __iomem *
+_vop_vq_configspace(struct mic_device_desc __iomem *desc)
+{
+	return _vop_vq_features(desc) + ioread8(&desc->feature_len) * 2;
+}
+
+static inline unsigned
+_vop_total_desc_size(struct mic_device_desc __iomem *desc)
+{
+	return _vop_aligned_desc_size(desc) + sizeof(struct mic_device_ctrl);
+}
+
+/* This gets the device's feature bits. */
+static u64 vop_get_features(struct virtio_device *vdev)
+{
+	unsigned int i, bits;
+	u32 features = 0;
+	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
+	u8 __iomem *in_features = _vop_vq_features(desc);
+	int feature_len = ioread8(&desc->feature_len);
+
+	bits = min_t(unsigned, feature_len, sizeof(vdev->features)) * 8;
+	for (i = 0; i < bits; i++)
+		if (ioread8(&in_features[i / 8]) & (BIT(i % 8)))
+			features |= BIT(i);
+
+	return features;
+}
+
+static int vop_finalize_features(struct virtio_device *vdev)
+{
+	unsigned int i, bits;
+	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
+	u8 feature_len = ioread8(&desc->feature_len);
+	/* Second half of bitmap is features we accept. */
+	u8 __iomem *out_features =
+		_vop_vq_features(desc) + feature_len;
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	memset_io(out_features, 0, feature_len);
+	bits = min_t(unsigned, feature_len,
+		     sizeof(vdev->features)) * 8;
+	for (i = 0; i < bits; i++) {
+		if (__virtio_test_bit(vdev, i))
+			iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
+				 &out_features[i / 8]);
+	}
+	return 0;
+}
+
+/*
+ * Reading and writing elements in config space
+ */
+static void vop_get(struct virtio_device *vdev, unsigned int offset,
+		    void *buf, unsigned len)
+{
+	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
+
+	if (offset + len > ioread8(&desc->config_len))
+		return;
+	memcpy_fromio(buf, _vop_vq_configspace(desc) + offset, len);
+}
+
+static void vop_set(struct virtio_device *vdev, unsigned int offset,
+		    const void *buf, unsigned len)
+{
+	struct mic_device_desc __iomem *desc = to_vopvdev(vdev)->desc;
+
+	if (offset + len > ioread8(&desc->config_len))
+		return;
+	memcpy_toio(_vop_vq_configspace(desc) + offset, buf, len);
+}
+
+/*
+ * The operations to get and set the status word just access the status
+ * field of the device descriptor. set_status also interrupts the host
+ * to tell about status changes.
+ */
+static u8 vop_get_status(struct virtio_device *vdev)
+{
+	return ioread8(&to_vopvdev(vdev)->desc->status);
+}
+
+static void vop_set_status(struct virtio_device *dev, u8 status)
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+	struct vop_device *vpdev = vdev->vpdev;
+
+	if (!status)
+		return;
+	iowrite8(status, &vdev->desc->status);
+	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
+}
+
+/* Inform host on a virtio device reset and wait for ack from host */
+static void vop_reset_inform_host(struct virtio_device *dev)
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+	struct mic_device_ctrl __iomem *dc = vdev->dc;
+	struct vop_device *vpdev = vdev->vpdev;
+	int retry;
+
+	iowrite8(0, &dc->host_ack);
+	iowrite8(1, &dc->vdev_reset);
+	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
+
+	/* Wait till host completes all card accesses and acks the reset */
+	for (retry = 100; retry--;) {
+		if (ioread8(&dc->host_ack))
+			break;
+		msleep(100);
+	};
+
+	dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);
+
+	/* Reset status to 0 in case we timed out */
+	iowrite8(0, &vdev->desc->status);
+}
+
+static void vop_reset(struct virtio_device *dev)
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+
+	dev_dbg(_vop_dev(vdev), "%s: virtio id %d\n",
+		__func__, dev->id.device);
+
+	vop_reset_inform_host(dev);
+	complete_all(&vdev->reset_done);
+}
+
+/*
+ * The virtio_ring code calls this API when it wants to notify the Host.
+ */
+static bool vop_notify(struct virtqueue *vq)
+{
+	struct _vop_vdev *vdev = vq->priv;
+	struct vop_device *vpdev = vdev->vpdev;
+
+	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
+	return true;
+}
+
+static void vop_del_vq(struct virtqueue *vq, int n)
+{
+	struct _vop_vdev *vdev = to_vopvdev(vq->vdev);
+	struct vring *vr = (struct vring *)(vq + 1);
+	struct vop_device *vpdev = vdev->vpdev;
+
+	dma_unmap_single(&vpdev->dev, vdev->used[n],
+			 vdev->used_size[n], DMA_BIDIRECTIONAL);
+	free_pages((unsigned long)vr->used, get_order(vdev->used_size[n]));
+	vring_del_virtqueue(vq);
+	vpdev->hw_ops->iounmap(vpdev, vdev->vr[n]);
+	vdev->vr[n] = NULL;
+}
+
+static void vop_del_vqs(struct virtio_device *dev)
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+	struct virtqueue *vq, *n;
+	int idx = 0;
+
+	dev_dbg(_vop_dev(vdev), "%s\n", __func__);
+
+	list_for_each_entry_safe(vq, n, &dev->vqs, list)
+		vop_del_vq(vq, idx++);
+}
+
+/*
+ * This routine will assign vring's allocated in host/io memory. Code in
+ * virtio_ring.c however continues to access this io memory as if it were local
+ * memory without io accessors.
+ */
+static struct virtqueue *vop_find_vq(struct virtio_device *dev,
+				     unsigned index,
+				     void (*callback)(struct virtqueue *vq),
+				     const char *name)
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+	struct vop_device *vpdev = vdev->vpdev;
+	struct mic_vqconfig __iomem *vqconfig;
+	struct mic_vqconfig config;
+	struct virtqueue *vq;
+	void __iomem *va;
+	struct _mic_vring_info __iomem *info;
+	void *used;
+	int vr_size, _vr_size, err, magic;
+	struct vring *vr;
+	u8 type = ioread8(&vdev->desc->type);
+
+	if (index >= ioread8(&vdev->desc->num_vq))
+		return ERR_PTR(-ENOENT);
+
+	if (!name)
+		return ERR_PTR(-ENOENT);
+
+	/* First assign the vring's allocated in host memory */
+	vqconfig = _vop_vq_config(vdev->desc) + index;
+	memcpy_fromio(&config, vqconfig, sizeof(config));
+	_vr_size = vring_size(le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN);
+	vr_size = PAGE_ALIGN(_vr_size + sizeof(struct _mic_vring_info));
+	va = vpdev->hw_ops->ioremap(vpdev, le64_to_cpu(config.address),
+			vr_size);
+	if (!va)
+		return ERR_PTR(-ENOMEM);
+	vdev->vr[index] = va;
+	memset_io(va, 0x0, _vr_size);
+	vq = vring_new_virtqueue(
+				index,
+				le16_to_cpu(config.num), MIC_VIRTIO_RING_ALIGN,
+				dev,
+				false,
+				(void __force *)va, vop_notify, callback, name);
+	if (!vq) {
+		err = -ENOMEM;
+		goto unmap;
+	}
+	info = va + _vr_size;
+	magic = ioread32(&info->magic);
+
+	if (WARN(magic != MIC_MAGIC + type + index, "magic mismatch")) {
+		err = -EIO;
+		goto unmap;
+	}
+
+	/* Allocate and reassign used ring now */
+	vdev->used_size[index] = PAGE_ALIGN(sizeof(__u16) * 3 +
+					     sizeof(struct vring_used_elem) *
+					     le16_to_cpu(config.num));
+	used = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
+					get_order(vdev->used_size[index]));
+	if (!used) {
+		err = -ENOMEM;
+		dev_err(_vop_dev(vdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto del_vq;
+	}
+	vdev->used[index] = dma_map_single(&vpdev->dev, used,
+					    vdev->used_size[index],
+					    DMA_BIDIRECTIONAL);
+	if (dma_mapping_error(&vpdev->dev, vdev->used[index])) {
+		err = -ENOMEM;
+		dev_err(_vop_dev(vdev), "%s %d err %d\n",
+			__func__, __LINE__, err);
+		goto free_used;
+	}
+	writeq(vdev->used[index], &vqconfig->used_address);
+	/*
+	 * To reassign the used ring here we are directly accessing
+	 * struct vring_virtqueue which is a private data structure
+	 * in virtio_ring.c. At the minimum, a BUILD_BUG_ON() in
+	 * vring_new_virtqueue() would ensure that
+	 *  (&vq->vring == (struct vring *) (&vq->vq + 1));
+	 */
+	vr = (struct vring *)(vq + 1);
+	vr->used = used;
+
+	vq->priv = vdev;
+	return vq;
+free_used:
+	free_pages((unsigned long)used,
+		   get_order(vdev->used_size[index]));
+del_vq:
+	vring_del_virtqueue(vq);
+unmap:
+	vpdev->hw_ops->iounmap(vpdev, vdev->vr[index]);
+	return ERR_PTR(err);
+}
+
+static int vop_find_vqs(struct virtio_device *dev, unsigned nvqs,
+			struct virtqueue *vqs[],
+			vq_callback_t *callbacks[],
+			const char * const names[])
+{
+	struct _vop_vdev *vdev = to_vopvdev(dev);
+	struct vop_device *vpdev = vdev->vpdev;
+	struct mic_device_ctrl __iomem *dc = vdev->dc;
+	int i, err, retry;
+
+	/* We must have this many virtqueues. */
+	if (nvqs > ioread8(&vdev->desc->num_vq))
+		return -ENOENT;
+
+	for (i = 0; i < nvqs; ++i) {
+		dev_dbg(_vop_dev(vdev), "%s: %d: %s\n",
+			__func__, i, names[i]);
+		vqs[i] = vop_find_vq(dev, i, callbacks[i], names[i]);
+		if (IS_ERR(vqs[i])) {
+			err = PTR_ERR(vqs[i]);
+			goto error;
+		}
+	}
+
+	iowrite8(1, &dc->used_address_updated);
+	/*
+	 * Send an interrupt to the host to inform it that used
+	 * rings have been re-assigned.
+	 */
+	vpdev->hw_ops->send_intr(vpdev, vdev->c2h_vdev_db);
+	for (retry = 100; retry--;) {
+		if (!ioread8(&dc->used_address_updated))
+			break;
+		msleep(100);
+	};
+
+	dev_dbg(_vop_dev(vdev), "%s: retry: %d\n", __func__, retry);
+	if (!retry) {
+		err = -ENODEV;
+		goto error;
+	}
+
+	return 0;
+error:
+	vop_del_vqs(dev);
+	return err;
+}
+
+/*
+ * The config ops structure as defined by virtio config
+ */
+static struct virtio_config_ops vop_vq_config_ops = {
+	.get_features = vop_get_features,
+	.finalize_features = vop_finalize_features,
+	.get = vop_get,
+	.set = vop_set,
+	.get_status = vop_get_status,
+	.set_status = vop_set_status,
+	.reset = vop_reset,
+	.find_vqs = vop_find_vqs,
+	.del_vqs = vop_del_vqs,
+};
+
+static irqreturn_t vop_virtio_intr_handler(int irq, void *data)
+{
+	struct _vop_vdev *vdev = data;
+	struct vop_device *vpdev = vdev->vpdev;
+	struct virtqueue *vq;
+
+	vpdev->hw_ops->ack_interrupt(vpdev, vdev->h2c_vdev_db);
+	list_for_each_entry(vq, &vdev->vdev.vqs, list)
+		vring_interrupt(0, vq);
+
+	return IRQ_HANDLED;
+}
+
+static void vop_virtio_release_dev(struct device *_d)
+{
+	/*
+	 * No need for a release method similar to virtio PCI.
+	 * Provide an empty one to avoid getting a warning from core.
+	 */
+}
+
+/*
+ * adds a new device and register it with virtio
+ * appropriate drivers are loaded by the device model
+ */
+static int _vop_add_device(struct mic_device_desc __iomem *d,
+			   unsigned int offset, struct vop_device *vpdev,
+			   int dnode)
+{
+	struct _vop_vdev *vdev;
+	int ret;
+	u8 type = ioread8(&d->type);
+
+	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
+	if (!vdev)
+		return -ENOMEM;
+
+	vdev->vpdev = vpdev;
+	vdev->vdev.dev.parent = &vpdev->dev;
+	vdev->vdev.dev.release = vop_virtio_release_dev;
+	vdev->vdev.id.device = type;
+	vdev->vdev.config = &vop_vq_config_ops;
+	vdev->desc = d;
+	vdev->dc = (void __iomem *)d + _vop_aligned_desc_size(d);
+	vdev->dnode = dnode;
+	vdev->vdev.priv = (void *)(u64)dnode;
+	init_completion(&vdev->reset_done);
+
+	vdev->h2c_vdev_db = vpdev->hw_ops->next_db(vpdev);
+	vdev->virtio_cookie = vpdev->hw_ops->request_irq(vpdev,
+			vop_virtio_intr_handler, "virtio intr",
+			vdev, vdev->h2c_vdev_db);
+	if (IS_ERR(vdev->virtio_cookie)) {
+		ret = PTR_ERR(vdev->virtio_cookie);
+		goto kfree;
+	}
+	iowrite8((u8)vdev->h2c_vdev_db, &vdev->dc->h2c_vdev_db);
+	vdev->c2h_vdev_db = ioread8(&vdev->dc->c2h_vdev_db);
+
+	ret = register_virtio_device(&vdev->vdev);
+	if (ret) {
+		dev_err(_vop_dev(vdev),
+			"Failed to register vop device %u type %u\n",
+			offset, type);
+		goto free_irq;
+	}
+	writeq((u64)vdev, &vdev->dc->vdev);
+	dev_dbg(_vop_dev(vdev), "%s: registered vop device %u type %u vdev %p\n",
+		__func__, offset, type, vdev);
+
+	return 0;
+
+free_irq:
+	vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
+kfree:
+	kfree(vdev);
+	return ret;
+}
+
+/*
+ * match for a vop device with a specific desc pointer
+ */
+static int vop_match_desc(struct device *dev, void *data)
+{
+	struct virtio_device *_dev = dev_to_virtio(dev);
+	struct _vop_vdev *vdev = to_vopvdev(_dev);
+
+	return vdev->desc == (void __iomem *)data;
+}
+
+static void _vop_handle_config_change(struct mic_device_desc __iomem *d,
+				      unsigned int offset,
+				      struct vop_device *vpdev)
+{
+	struct mic_device_ctrl __iomem *dc
+		= (void __iomem *)d + _vop_aligned_desc_size(d);
+	struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);
+
+	if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
+		return;
+
+	dev_dbg(&vpdev->dev, "%s %d\n", __func__, __LINE__);
+	virtio_config_changed(&vdev->vdev);
+	iowrite8(1, &dc->guest_ack);
+}
+
+/*
+ * removes a virtio device if a hot remove event has been
+ * requested by the host.
+ */
+static int _vop_remove_device(struct mic_device_desc __iomem *d,
+			      unsigned int offset, struct vop_device *vpdev)
+{
+	struct mic_device_ctrl __iomem *dc
+		= (void __iomem *)d + _vop_aligned_desc_size(d);
+	struct _vop_vdev *vdev = (struct _vop_vdev *)readq(&dc->vdev);
+	u8 status;
+	int ret = -1;
+
+	if (ioread8(&dc->config_change) == MIC_VIRTIO_PARAM_DEV_REMOVE) {
+		dev_dbg(&vpdev->dev,
+			"%s %d config_change %d type %d vdev %p\n",
+			__func__, __LINE__,
+			ioread8(&dc->config_change), ioread8(&d->type), vdev);
+		status = ioread8(&d->status);
+		reinit_completion(&vdev->reset_done);
+		unregister_virtio_device(&vdev->vdev);
+		vpdev->hw_ops->free_irq(vpdev, vdev->virtio_cookie, vdev);
+		iowrite8(-1, &dc->h2c_vdev_db);
+		if (status & VIRTIO_CONFIG_S_DRIVER_OK)
+			wait_for_completion(&vdev->reset_done);
+		kfree(vdev);
+		iowrite8(1, &dc->guest_ack);
+		dev_dbg(&vpdev->dev, "%s %d guest_ack %d\n",
+			__func__, __LINE__, ioread8(&dc->guest_ack));
+		iowrite8(-1, &d->type);
+		ret = 0;
+	}
+	return ret;
+}
+
+#define REMOVE_DEVICES true
+
+static void _vop_scan_devices(void __iomem *dp, struct vop_device *vpdev,
+			      bool remove, int dnode)
+{
+	s8 type;
+	unsigned int i;
+	struct mic_device_desc __iomem *d;
+	struct mic_device_ctrl __iomem *dc;
+	struct device *dev;
+	int ret;
+
+	for (i = sizeof(struct mic_bootparam);
+			i < MIC_DP_SIZE; i += _vop_total_desc_size(d)) {
+		d = dp + i;
+		dc = (void __iomem *)d + _vop_aligned_desc_size(d);
+		/*
+		 * This read barrier is paired with the corresponding write
+		 * barrier on the host which is inserted before adding or
+		 * removing a virtio device descriptor, by updating the type.
+		 */
+		rmb();
+		type = ioread8(&d->type);
+
+		/* end of list */
+		if (type == 0)
+			break;
+
+		if (type == -1)
+			continue;
+
+		/* device already exists */
+		dev = device_find_child(&vpdev->dev, (void __force *)d,
+					vop_match_desc);
+		if (dev) {
+			if (remove)
+				iowrite8(MIC_VIRTIO_PARAM_DEV_REMOVE,
+					 &dc->config_change);
+			put_device(dev);
+			_vop_handle_config_change(d, i, vpdev);
+			ret = _vop_remove_device(d, i, vpdev);
+			if (remove) {
+				iowrite8(0, &dc->config_change);
+				iowrite8(0, &dc->guest_ack);
+			}
+			continue;
+		}
+
+		/* new device */
+		dev_dbg(&vpdev->dev, "%s %d Adding new virtio device %p\n",
+			__func__, __LINE__, d);
+		if (!remove)
+			_vop_add_device(d, i, vpdev, dnode);
+	}
+}
+
+static void vop_scan_devices(struct vop_info *vi,
+			     struct vop_device *vpdev, bool remove)
+{
+	void __iomem *dp = vpdev->hw_ops->get_remote_dp(vpdev);
+
+	if (!dp)
+		return;
+	mutex_lock(&vi->vop_mutex);
+	_vop_scan_devices(dp, vpdev, remove, vpdev->dnode);
+	mutex_unlock(&vi->vop_mutex);
+}
+
+/*
+ * vop_hotplug_device tries to find changes in the device page.
+ */
+static void vop_hotplug_devices(struct work_struct *work)
+{
+	struct vop_info *vi = container_of(work, struct vop_info,
+					     hotplug_work);
+
+	vop_scan_devices(vi, vi->vpdev, !REMOVE_DEVICES);
+}
+
+/*
+ * Interrupt handler for hot plug/config changes etc.
+ */
+static irqreturn_t vop_extint_handler(int irq, void *data)
+{
+	struct vop_info *vi = data;
+	struct mic_bootparam __iomem *bp;
+	struct vop_device *vpdev = vi->vpdev;
+
+	bp = vpdev->hw_ops->get_remote_dp(vpdev);
+	dev_dbg(&vpdev->dev, "%s %d hotplug work\n",
+		__func__, __LINE__);
+	vpdev->hw_ops->ack_interrupt(vpdev, ioread8(&bp->h2c_config_db));
+	schedule_work(&vi->hotplug_work);
+	return IRQ_HANDLED;
+}
+
+static int vop_driver_probe(struct vop_device *vpdev)
+{
+	struct vop_info *vi;
+	int rc;
+
+	vi = kzalloc(sizeof(*vi), GFP_KERNEL);
+	if (!vi) {
+		rc = -ENOMEM;
+		goto exit;
+	}
+	vpdev->priv = vi;
+	vi->vpdev = vpdev;
+
+	mutex_init(&vi->vop_mutex);
+	INIT_WORK(&vi->hotplug_work, vop_hotplug_devices);
+	if (vpdev->dnode) {
+		rc = vop_host_init(vi);
+		if (rc < 0)
+			goto free;
+	} else {
+		struct mic_bootparam __iomem *bootparam;
+
+		vop_scan_devices(vi, vpdev, !REMOVE_DEVICES);
+
+		vi->h2c_config_db = vpdev->hw_ops->next_db(vpdev);
+		vi->cookie = vpdev->hw_ops->request_irq(vpdev,
+							vop_extint_handler,
+							"virtio_config_intr",
+							vi, vi->h2c_config_db);
+		if (IS_ERR(vi->cookie)) {
+			rc = PTR_ERR(vi->cookie);
+			goto free;
+		}
+		bootparam = vpdev->hw_ops->get_remote_dp(vpdev);
+		iowrite8(vi->h2c_config_db, &bootparam->h2c_config_db);
+	}
+	vop_init_debugfs(vi);
+	return 0;
+free:
+	kfree(vi);
+exit:
+	return rc;
+}
+
+static void vop_driver_remove(struct vop_device *vpdev)
+{
+	struct vop_info *vi = vpdev->priv;
+
+	if (vpdev->dnode) {
+		vop_host_uninit(vi);
+	} else {
+		struct mic_bootparam __iomem *bootparam =
+			vpdev->hw_ops->get_remote_dp(vpdev);
+		if (bootparam)
+			iowrite8(-1, &bootparam->h2c_config_db);
+		vpdev->hw_ops->free_irq(vpdev, vi->cookie, vi);
+		flush_work(&vi->hotplug_work);
+		vop_scan_devices(vi, vpdev, REMOVE_DEVICES);
+	}
+	vop_exit_debugfs(vi);
+	kfree(vi);
+}
+
+static struct vop_device_id id_table[] = {
+	{ VOP_DEV_TRNSP, VOP_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct vop_driver vop_driver = {
+	.driver.name =	KBUILD_MODNAME,
+	.driver.owner =	THIS_MODULE,
+	.id_table = id_table,
+	.probe = vop_driver_probe,
+	.remove = vop_driver_remove,
+};
+
+module_vop_driver(vop_driver);
+
+MODULE_DEVICE_TABLE(mbus, id_table);
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("Intel(R) Virtio Over PCIe (VOP) driver");
+MODULE_LICENSE("GPL v2");
-- 
1.8.2.1