drivers/misc/mic/card/mic_virtio.c - arm/linux-arm64-legacy - Git at Google

 /*
  * Intel MIC Platform Software Stack (MPSS)
  *
  * Copyright(c) 2013 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".
  *
  * Disclaimer: The codes contained in these modules may be specific to
  * the Intel Software Development Platform codenamed: Knights Ferry, and
  * the Intel product codenamed: Knights Corner, and are not backward
  * compatible with other Intel products. Additionally, Intel will NOT
  * support the codes or instruction set in future products.
  *
  * 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@de.ibm.com>
  *
  * Intel MIC Card driver.
  *
  */
 #include <linux/delay.h>
 #include <linux/slab.h>
 #include <linux/virtio_config.h>

 #include "../common/mic_dev.h"
 #include "mic_virtio.h"

 #define VIRTIO_SUBCODE_64 0x0D00

 #define MIC_MAX_VRINGS                4
 struct mic_vdev {
 	struct virtio_device vdev;
 	struct mic_device_desc __iomem *desc;
 	struct mic_device_ctrl __iomem *dc;
 	struct mic_device *mdev;
 	void __iomem *vr[MIC_MAX_VRINGS];
 	int used_size[MIC_MAX_VRINGS];
 	struct completion reset_done;
 	struct mic_irq *virtio_cookie;
 	int c2h_vdev_db;
 };

 static struct mic_irq *virtio_config_cookie;
 #define to_micvdev(vd) container_of(vd, struct mic_vdev, vdev)

 /* Helper API to obtain the parent of the virtio device */
 static inline struct device *mic_dev(struct mic_vdev *mvdev)
 {
 	return mvdev->vdev.dev.parent;
 }

 /* This gets the device's feature bits. */
 static u32 mic_get_features(struct virtio_device *vdev)
 {
 	unsigned int i, bits;
 	u32 features = 0;
 	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;
 	u8 __iomem *in_features = mic_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 void mic_finalize_features(struct virtio_device *vdev)
 {
 	unsigned int i, bits;
 	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;
 	u8 feature_len = ioread8(&desc->feature_len);
 	/* Second half of bitmap is features we accept. */
 	u8 __iomem *out_features =
 		mic_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 (test_bit(i, vdev->features))
 			iowrite8(ioread8(&out_features[i / 8]) | (1 << (i % 8)),
 				 &out_features[i / 8]);
 	}
 }

 /*
  * Reading and writing elements in config space
  */
 static void mic_get(struct virtio_device *vdev, unsigned int offset,
 		   void *buf, unsigned len)
 {
 	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;

 	if (offset + len > ioread8(&desc->config_len))
 		return;
 	memcpy_fromio(buf, mic_vq_configspace(desc) + offset, len);
 }

 static void mic_set(struct virtio_device *vdev, unsigned int offset,
 		   const void *buf, unsigned len)
 {
 	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;

 	if (offset + len > ioread8(&desc->config_len))
 		return;
 	memcpy_toio(mic_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 mic_get_status(struct virtio_device *vdev)
 {
 	return ioread8(&to_micvdev(vdev)->desc->status);
 }

 static void mic_set_status(struct virtio_device *vdev, u8 status)
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);
 	if (!status)
 		return;
 	iowrite8(status, &mvdev->desc->status);
 	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
 }

 /* Inform host on a virtio device reset and wait for ack from host */
 static void mic_reset_inform_host(struct virtio_device *vdev)
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);
 	struct mic_device_ctrl __iomem *dc = mvdev->dc;
 	int retry;

 	iowrite8(0, &dc->host_ack);
 	iowrite8(1, &dc->vdev_reset);
 	mic_send_intr(mvdev->mdev, mvdev->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(mic_dev(mvdev), "%s: retry: %d\n", __func__, retry);

 	/* Reset status to 0 in case we timed out */
 	iowrite8(0, &mvdev->desc->status);
 }

 static void mic_reset(struct virtio_device *vdev)
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);

 	dev_dbg(mic_dev(mvdev), "%s: virtio id %d\n",
 		__func__, vdev->id.device);

 	mic_reset_inform_host(vdev);
 	complete_all(&mvdev->reset_done);
 }

 /*
  * The virtio_ring code calls this API when it wants to notify the Host.
  */
 static bool mic_notify(struct virtqueue *vq)
 {
 	struct mic_vdev *mvdev = vq->priv;

 	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
 	return true;
 }

 static void mic_del_vq(struct virtqueue *vq, int n)
 {
 	struct mic_vdev *mvdev = to_micvdev(vq->vdev);
 	struct vring *vr = (struct vring *)(vq + 1);

 	free_pages((unsigned long) vr->used, get_order(mvdev->used_size[n]));
 	vring_del_virtqueue(vq);
 	mic_card_unmap(mvdev->mdev, mvdev->vr[n]);
 	mvdev->vr[n] = NULL;
 }

 static void mic_del_vqs(struct virtio_device *vdev)
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);
 	struct virtqueue *vq, *n;
 	int idx = 0;

 	dev_dbg(mic_dev(mvdev), "%s\n", __func__);

 	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
 		mic_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 *mic_find_vq(struct virtio_device *vdev,
 				     unsigned index,
 				     void (*callback)(struct virtqueue *vq),
 				     const char *name)
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);
 	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(&mvdev->desc->type);

 	if (index >= ioread8(&mvdev->desc->num_vq))
 		return ERR_PTR(-ENOENT);

 	if (!name)
 		return ERR_PTR(-ENOENT);

 	/* First assign the vring's allocated in host memory */
 	vqconfig = mic_vq_config(mvdev->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 = mic_card_map(mvdev->mdev, le64_to_cpu(config.address), vr_size);
 	if (!va)
 		return ERR_PTR(-ENOMEM);
 	mvdev->vr[index] = va;
 	memset_io(va, 0x0, _vr_size);
 	vq = vring_new_virtqueue(index, le16_to_cpu(config.num),
 				 MIC_VIRTIO_RING_ALIGN, vdev, false,
 				 (void __force *)va, mic_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 */
 	mvdev->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(mvdev->used_size[index]));
 	if (!used) {
 		err = -ENOMEM;
 		dev_err(mic_dev(mvdev), "%s %d err %d\n",
 			__func__, __LINE__, err);
 		goto del_vq;
 	}
 	iowrite64(virt_to_phys(used), &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 = mvdev;
 	return vq;
 del_vq:
 	vring_del_virtqueue(vq);
 unmap:
 	mic_card_unmap(mvdev->mdev, mvdev->vr[index]);
 	return ERR_PTR(err);
 }

 static int mic_find_vqs(struct virtio_device *vdev, unsigned nvqs,
 			struct virtqueue *vqs[],
 			vq_callback_t *callbacks[],
 			const char *names[])
 {
 	struct mic_vdev *mvdev = to_micvdev(vdev);
 	struct mic_device_ctrl __iomem *dc = mvdev->dc;
 	int i, err, retry;

 	/* We must have this many virtqueues. */
 	if (nvqs > ioread8(&mvdev->desc->num_vq))
 		return -ENOENT;

 	for (i = 0; i < nvqs; ++i) {
 		dev_dbg(mic_dev(mvdev), "%s: %d: %s\n",
 			__func__, i, names[i]);
 		vqs[i] = mic_find_vq(vdev, 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.
 	 */
 	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
 	for (retry = 100; retry--;) {
 		if (!ioread8(&dc->used_address_updated))
 			break;
 		msleep(100);
 	};

 	dev_dbg(mic_dev(mvdev), "%s: retry: %d\n", __func__, retry);
 	if (!retry) {
 		err = -ENODEV;
 		goto error;
 	}

 	return 0;
 error:
 	mic_del_vqs(vdev);
 	return err;
 }

 /*
  * The config ops structure as defined by virtio config
  */
 static struct virtio_config_ops mic_vq_config_ops = {
 	.get_features = mic_get_features,
 	.finalize_features = mic_finalize_features,
 	.get = mic_get,
 	.set = mic_set,
 	.get_status = mic_get_status,
 	.set_status = mic_set_status,
 	.reset = mic_reset,
 	.find_vqs = mic_find_vqs,
 	.del_vqs = mic_del_vqs,
 };

 static irqreturn_t
 mic_virtio_intr_handler(int irq, void *data)
 {
 	struct mic_vdev *mvdev = data;
 	struct virtqueue *vq;

 	mic_ack_interrupt(mvdev->mdev);
 	list_for_each_entry(vq, &mvdev->vdev.vqs, list)
 		vring_interrupt(0, vq);

 	return IRQ_HANDLED;
 }

 static void mic_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 mic_add_device(struct mic_device_desc __iomem *d,
 	unsigned int offset, struct mic_driver *mdrv)
 {
 	struct mic_vdev *mvdev;
 	int ret;
 	int virtio_db;
 	u8 type = ioread8(&d->type);

 	mvdev = kzalloc(sizeof(*mvdev), GFP_KERNEL);
 	if (!mvdev) {
 		dev_err(mdrv->dev, "Cannot allocate mic dev %u type %u\n",
 			offset, type);
 		return -ENOMEM;
 	}

 	mvdev->mdev = &mdrv->mdev;
 	mvdev->vdev.dev.parent = mdrv->dev;
 	mvdev->vdev.dev.release = mic_virtio_release_dev;
 	mvdev->vdev.id.device = type;
 	mvdev->vdev.config = &mic_vq_config_ops;
 	mvdev->desc = d;
 	mvdev->dc = (void __iomem *)d + mic_aligned_desc_size(d);
 	init_completion(&mvdev->reset_done);

 	virtio_db = mic_next_card_db();
 	mvdev->virtio_cookie = mic_request_card_irq(mic_virtio_intr_handler,
 			"virtio intr", mvdev, virtio_db);
 	if (IS_ERR(mvdev->virtio_cookie)) {
 		ret = PTR_ERR(mvdev->virtio_cookie);
 		goto kfree;
 	}
 	iowrite8((u8)virtio_db, &mvdev->dc->h2c_vdev_db);
 	mvdev->c2h_vdev_db = ioread8(&mvdev->dc->c2h_vdev_db);

 	ret = register_virtio_device(&mvdev->vdev);
 	if (ret) {
 		dev_err(mic_dev(mvdev),
 			"Failed to register mic device %u type %u\n",
 			offset, type);
 		goto free_irq;
 	}
 	iowrite64((u64)mvdev, &mvdev->dc->vdev);
 	dev_dbg(mic_dev(mvdev), "%s: registered mic device %u type %u mvdev %p\n",
 		__func__, offset, type, mvdev);

 	return 0;

 free_irq:
 	mic_free_card_irq(mvdev->virtio_cookie, mvdev);
 kfree:
 	kfree(mvdev);
 	return ret;
 }

 /*
  * match for a mic device with a specific desc pointer
  */
 static int mic_match_desc(struct device *dev, void *data)
 {
 	struct virtio_device *vdev = dev_to_virtio(dev);
 	struct mic_vdev *mvdev = to_micvdev(vdev);

 	return mvdev->desc == (void __iomem *)data;
 }

 static void mic_handle_config_change(struct mic_device_desc __iomem *d,
 	unsigned int offset, struct mic_driver *mdrv)
 {
 	struct mic_device_ctrl __iomem *dc
 		= (void __iomem *)d + mic_aligned_desc_size(d);
 	struct mic_vdev *mvdev = (struct mic_vdev *)ioread64(&dc->vdev);
 	struct virtio_driver *drv;

 	if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
 		return;

 	dev_dbg(mdrv->dev, "%s %d\n", __func__, __LINE__);
 	drv = container_of(mvdev->vdev.dev.driver,
 				struct virtio_driver, driver);
 	if (drv->config_changed)
 		drv->config_changed(&mvdev->vdev);
 	iowrite8(1, &dc->guest_ack);
 }

 /*
  * removes a virtio device if a hot remove event has been
  * requested by the host.
  */
 static int mic_remove_device(struct mic_device_desc __iomem *d,
 	unsigned int offset, struct mic_driver *mdrv)
 {
 	struct mic_device_ctrl __iomem *dc
 		= (void __iomem *)d + mic_aligned_desc_size(d);
 	struct mic_vdev *mvdev = (struct mic_vdev *)ioread64(&dc->vdev);
 	u8 status;
 	int ret = -1;

 	if (ioread8(&dc->config_change) == MIC_VIRTIO_PARAM_DEV_REMOVE) {
 		dev_dbg(mdrv->dev,
 			"%s %d config_change %d type %d mvdev %p\n",
 			__func__, __LINE__,
 			ioread8(&dc->config_change), ioread8(&d->type), mvdev);

 		status = ioread8(&d->status);
 		reinit_completion(&mvdev->reset_done);
 		unregister_virtio_device(&mvdev->vdev);
 		mic_free_card_irq(mvdev->virtio_cookie, mvdev);
 		if (status & VIRTIO_CONFIG_S_DRIVER_OK)
 			wait_for_completion(&mvdev->reset_done);
 		kfree(mvdev);
 		iowrite8(1, &dc->guest_ack);
 		dev_dbg(mdrv->dev, "%s %d guest_ack %d\n",
 			__func__, __LINE__, ioread8(&dc->guest_ack));
 		ret = 0;
 	}

 	return ret;
 }

 #define REMOVE_DEVICES true

 static void mic_scan_devices(struct mic_driver *mdrv, bool remove)
 {
 	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 += mic_total_desc_size(d)) {
 		d = mdrv->dp + i;
 		dc = (void __iomem *)d + mic_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(mdrv->dev, (void __force *)d,
 					mic_match_desc);
 		if (dev) {
 			if (remove)
 				iowrite8(MIC_VIRTIO_PARAM_DEV_REMOVE,
 					 &dc->config_change);
 			put_device(dev);
 			mic_handle_config_change(d, i, mdrv);
 			ret = mic_remove_device(d, i, mdrv);
 			if (!ret && !remove)
 				iowrite8(-1, &d->type);
 			if (remove) {
 				iowrite8(0, &dc->config_change);
 				iowrite8(0, &dc->guest_ack);
 			}
 			continue;
 		}

 		/* new device */
 		dev_dbg(mdrv->dev, "%s %d Adding new virtio device %p\n",
 			__func__, __LINE__, d);
 		if (!remove)
 			mic_add_device(d, i, mdrv);
 	}
 }

 /*
  * mic_hotplug_device tries to find changes in the device page.
  */
 static void mic_hotplug_devices(struct work_struct *work)
 {
 	struct mic_driver *mdrv = container_of(work,
 		struct mic_driver, hotplug_work);

 	mic_scan_devices(mdrv, !REMOVE_DEVICES);
 }

 /*
  * Interrupt handler for hot plug/config changes etc.
  */
 static irqreturn_t
 mic_extint_handler(int irq, void *data)
 {
 	struct mic_driver *mdrv = (struct mic_driver *)data;

 	dev_dbg(mdrv->dev, "%s %d hotplug work\n",
 		__func__, __LINE__);
 	mic_ack_interrupt(&mdrv->mdev);
 	schedule_work(&mdrv->hotplug_work);
 	return IRQ_HANDLED;
 }

 /*
  * Init function for virtio
  */
 int mic_devices_init(struct mic_driver *mdrv)
 {
 	int rc;
 	struct mic_bootparam __iomem *bootparam;
 	int config_db;

 	INIT_WORK(&mdrv->hotplug_work, mic_hotplug_devices);
 	mic_scan_devices(mdrv, !REMOVE_DEVICES);

 	config_db = mic_next_card_db();
 	virtio_config_cookie = mic_request_card_irq(mic_extint_handler,
 			"virtio_config_intr", mdrv, config_db);
 	if (IS_ERR(virtio_config_cookie)) {
 		rc = PTR_ERR(virtio_config_cookie);
 		goto exit;
 	}

 	bootparam = mdrv->dp;
 	iowrite8(config_db, &bootparam->h2c_config_db);
 	return 0;
 exit:
 	return rc;
 }

 /*
  * Uninit function for virtio
  */
 void mic_devices_uninit(struct mic_driver *mdrv)
 {
 	struct mic_bootparam __iomem *bootparam = mdrv->dp;
 	iowrite8(-1, &bootparam->h2c_config_db);
 	mic_free_card_irq(virtio_config_cookie, mdrv);
 	flush_work(&mdrv->hotplug_work);
 	mic_scan_devices(mdrv, REMOVE_DEVICES);
 }
	/*
	* Intel MIC Platform Software Stack (MPSS)
	*
	* Copyright(c) 2013 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".
	*
	* Disclaimer: The codes contained in these modules may be specific to
	* the Intel Software Development Platform codenamed: Knights Ferry, and
	* the Intel product codenamed: Knights Corner, and are not backward
	* compatible with other Intel products. Additionally, Intel will NOT
	* support the codes or instruction set in future products.
	*
	* 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@de.ibm.com>
	*
	* Intel MIC Card driver.
	*
	*/
	#include <linux/delay.h>
	#include <linux/slab.h>
	#include <linux/virtio_config.h>

	#include "../common/mic_dev.h"
	#include "mic_virtio.h"

	#define VIRTIO_SUBCODE_64 0x0D00

	#define MIC_MAX_VRINGS 4
	struct mic_vdev {
	struct virtio_device vdev;
	struct mic_device_desc __iomem *desc;
	struct mic_device_ctrl __iomem *dc;
	struct mic_device *mdev;
	void __iomem *vr[MIC_MAX_VRINGS];
	int used_size[MIC_MAX_VRINGS];
	struct completion reset_done;
	struct mic_irq *virtio_cookie;
	int c2h_vdev_db;
	};

	static struct mic_irq *virtio_config_cookie;
	#define to_micvdev(vd) container_of(vd, struct mic_vdev, vdev)

	/* Helper API to obtain the parent of the virtio device */
	static inline struct device mic_dev(struct mic_vdev mvdev)
	{
	return mvdev->vdev.dev.parent;
	}

	/* This gets the device's feature bits. */
	static u32 mic_get_features(struct virtio_device *vdev)
	{
	unsigned int i, bits;
	u32 features = 0;
	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;
	u8 __iomem *in_features = mic_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 void mic_finalize_features(struct virtio_device *vdev)
	{
	unsigned int i, bits;
	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;
	u8 feature_len = ioread8(&desc->feature_len);
	/* Second half of bitmap is features we accept. */
	u8 __iomem *out_features =
	mic_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 (test_bit(i, vdev->features))
	iowrite8(ioread8(&out_features[i / 8]) \| (1 << (i % 8)),
	&out_features[i / 8]);
	}
	}

	/*
	* Reading and writing elements in config space
	*/
	static void mic_get(struct virtio_device *vdev, unsigned int offset,
	void *buf, unsigned len)
	{
	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;

	if (offset + len > ioread8(&desc->config_len))
	return;
	memcpy_fromio(buf, mic_vq_configspace(desc) + offset, len);
	}

	static void mic_set(struct virtio_device *vdev, unsigned int offset,
	const void *buf, unsigned len)
	{
	struct mic_device_desc __iomem *desc = to_micvdev(vdev)->desc;

	if (offset + len > ioread8(&desc->config_len))
	return;
	memcpy_toio(mic_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 mic_get_status(struct virtio_device *vdev)
	{
	return ioread8(&to_micvdev(vdev)->desc->status);
	}

	static void mic_set_status(struct virtio_device *vdev, u8 status)
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);
	if (!status)
	return;
	iowrite8(status, &mvdev->desc->status);
	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
	}

	/* Inform host on a virtio device reset and wait for ack from host */
	static void mic_reset_inform_host(struct virtio_device *vdev)
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);
	struct mic_device_ctrl __iomem *dc = mvdev->dc;
	int retry;

	iowrite8(0, &dc->host_ack);
	iowrite8(1, &dc->vdev_reset);
	mic_send_intr(mvdev->mdev, mvdev->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(mic_dev(mvdev), "%s: retry: %d\n", __func__, retry);

	/* Reset status to 0 in case we timed out */
	iowrite8(0, &mvdev->desc->status);
	}

	static void mic_reset(struct virtio_device *vdev)
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);

	dev_dbg(mic_dev(mvdev), "%s: virtio id %d\n",
	__func__, vdev->id.device);

	mic_reset_inform_host(vdev);
	complete_all(&mvdev->reset_done);
	}

	/*
	* The virtio_ring code calls this API when it wants to notify the Host.
	*/
	static bool mic_notify(struct virtqueue *vq)
	{
	struct mic_vdev *mvdev = vq->priv;

	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
	return true;
	}

	static void mic_del_vq(struct virtqueue *vq, int n)
	{
	struct mic_vdev *mvdev = to_micvdev(vq->vdev);
	struct vring vr = (struct vring )(vq + 1);

	free_pages((unsigned long) vr->used, get_order(mvdev->used_size[n]));
	vring_del_virtqueue(vq);
	mic_card_unmap(mvdev->mdev, mvdev->vr[n]);
	mvdev->vr[n] = NULL;
	}

	static void mic_del_vqs(struct virtio_device *vdev)
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);
	struct virtqueue vq, n;
	int idx = 0;

	dev_dbg(mic_dev(mvdev), "%s\n", __func__);

	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
	mic_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 mic_find_vq(struct virtio_device vdev,
	unsigned index,
	void (callback)(struct virtqueue vq),
	const char *name)
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);
	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(&mvdev->desc->type);

	if (index >= ioread8(&mvdev->desc->num_vq))
	return ERR_PTR(-ENOENT);

	if (!name)
	return ERR_PTR(-ENOENT);

	/* First assign the vring's allocated in host memory */
	vqconfig = mic_vq_config(mvdev->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 = mic_card_map(mvdev->mdev, le64_to_cpu(config.address), vr_size);
	if (!va)
	return ERR_PTR(-ENOMEM);
	mvdev->vr[index] = va;
	memset_io(va, 0x0, _vr_size);
	vq = vring_new_virtqueue(index, le16_to_cpu(config.num),
	MIC_VIRTIO_RING_ALIGN, vdev, false,
	(void __force *)va, mic_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 */
	mvdev->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(mvdev->used_size[index]));
	if (!used) {
	err = -ENOMEM;
	dev_err(mic_dev(mvdev), "%s %d err %d\n",
	__func__, __LINE__, err);
	goto del_vq;
	}
	iowrite64(virt_to_phys(used), &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 = mvdev;
	return vq;
	del_vq:
	vring_del_virtqueue(vq);
	unmap:
	mic_card_unmap(mvdev->mdev, mvdev->vr[index]);
	return ERR_PTR(err);
	}

	static int mic_find_vqs(struct virtio_device *vdev, unsigned nvqs,
	struct virtqueue *vqs[],
	vq_callback_t *callbacks[],
	const char *names[])
	{
	struct mic_vdev *mvdev = to_micvdev(vdev);
	struct mic_device_ctrl __iomem *dc = mvdev->dc;
	int i, err, retry;

	/* We must have this many virtqueues. */
	if (nvqs > ioread8(&mvdev->desc->num_vq))
	return -ENOENT;

	for (i = 0; i < nvqs; ++i) {
	dev_dbg(mic_dev(mvdev), "%s: %d: %s\n",
	__func__, i, names[i]);
	vqs[i] = mic_find_vq(vdev, 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.
	*/
	mic_send_intr(mvdev->mdev, mvdev->c2h_vdev_db);
	for (retry = 100; retry--;) {
	if (!ioread8(&dc->used_address_updated))
	break;
	msleep(100);
	};

	dev_dbg(mic_dev(mvdev), "%s: retry: %d\n", __func__, retry);
	if (!retry) {
	err = -ENODEV;
	goto error;
	}

	return 0;
	error:
	mic_del_vqs(vdev);
	return err;
	}

	/*
	* The config ops structure as defined by virtio config
	*/
	static struct virtio_config_ops mic_vq_config_ops = {
	.get_features = mic_get_features,
	.finalize_features = mic_finalize_features,
	.get = mic_get,
	.set = mic_set,
	.get_status = mic_get_status,
	.set_status = mic_set_status,
	.reset = mic_reset,
	.find_vqs = mic_find_vqs,
	.del_vqs = mic_del_vqs,
	};

	static irqreturn_t
	mic_virtio_intr_handler(int irq, void *data)
	{
	struct mic_vdev *mvdev = data;
	struct virtqueue *vq;

	mic_ack_interrupt(mvdev->mdev);
	list_for_each_entry(vq, &mvdev->vdev.vqs, list)
	vring_interrupt(0, vq);

	return IRQ_HANDLED;
	}

	static void mic_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 mic_add_device(struct mic_device_desc __iomem *d,
	unsigned int offset, struct mic_driver *mdrv)
	{
	struct mic_vdev *mvdev;
	int ret;
	int virtio_db;
	u8 type = ioread8(&d->type);

	mvdev = kzalloc(sizeof(*mvdev), GFP_KERNEL);
	if (!mvdev) {
	dev_err(mdrv->dev, "Cannot allocate mic dev %u type %u\n",
	offset, type);
	return -ENOMEM;
	}

	mvdev->mdev = &mdrv->mdev;
	mvdev->vdev.dev.parent = mdrv->dev;
	mvdev->vdev.dev.release = mic_virtio_release_dev;
	mvdev->vdev.id.device = type;
	mvdev->vdev.config = &mic_vq_config_ops;
	mvdev->desc = d;
	mvdev->dc = (void __iomem *)d + mic_aligned_desc_size(d);
	init_completion(&mvdev->reset_done);

	virtio_db = mic_next_card_db();
	mvdev->virtio_cookie = mic_request_card_irq(mic_virtio_intr_handler,
	"virtio intr", mvdev, virtio_db);
	if (IS_ERR(mvdev->virtio_cookie)) {
	ret = PTR_ERR(mvdev->virtio_cookie);
	goto kfree;
	}
	iowrite8((u8)virtio_db, &mvdev->dc->h2c_vdev_db);
	mvdev->c2h_vdev_db = ioread8(&mvdev->dc->c2h_vdev_db);

	ret = register_virtio_device(&mvdev->vdev);
	if (ret) {
	dev_err(mic_dev(mvdev),
	"Failed to register mic device %u type %u\n",
	offset, type);
	goto free_irq;
	}
	iowrite64((u64)mvdev, &mvdev->dc->vdev);
	dev_dbg(mic_dev(mvdev), "%s: registered mic device %u type %u mvdev %p\n",
	__func__, offset, type, mvdev);

	return 0;

	free_irq:
	mic_free_card_irq(mvdev->virtio_cookie, mvdev);
	kfree:
	kfree(mvdev);
	return ret;
	}

	/*
	* match for a mic device with a specific desc pointer
	*/
	static int mic_match_desc(struct device dev, void data)
	{
	struct virtio_device *vdev = dev_to_virtio(dev);
	struct mic_vdev *mvdev = to_micvdev(vdev);

	return mvdev->desc == (void __iomem *)data;
	}

	static void mic_handle_config_change(struct mic_device_desc __iomem *d,
	unsigned int offset, struct mic_driver *mdrv)
	{
	struct mic_device_ctrl __iomem *dc
	= (void __iomem *)d + mic_aligned_desc_size(d);
	struct mic_vdev mvdev = (struct mic_vdev )ioread64(&dc->vdev);
	struct virtio_driver *drv;

	if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
	return;

	dev_dbg(mdrv->dev, "%s %d\n", __func__, __LINE__);
	drv = container_of(mvdev->vdev.dev.driver,
	struct virtio_driver, driver);
	if (drv->config_changed)
	drv->config_changed(&mvdev->vdev);
	iowrite8(1, &dc->guest_ack);
	}

	/*
	* removes a virtio device if a hot remove event has been
	* requested by the host.
	*/
	static int mic_remove_device(struct mic_device_desc __iomem *d,
	unsigned int offset, struct mic_driver *mdrv)
	{
	struct mic_device_ctrl __iomem *dc
	= (void __iomem *)d + mic_aligned_desc_size(d);
	struct mic_vdev mvdev = (struct mic_vdev )ioread64(&dc->vdev);
	u8 status;
	int ret = -1;

	if (ioread8(&dc->config_change) == MIC_VIRTIO_PARAM_DEV_REMOVE) {
	dev_dbg(mdrv->dev,
	"%s %d config_change %d type %d mvdev %p\n",
	__func__, __LINE__,
	ioread8(&dc->config_change), ioread8(&d->type), mvdev);

	status = ioread8(&d->status);
	reinit_completion(&mvdev->reset_done);
	unregister_virtio_device(&mvdev->vdev);
	mic_free_card_irq(mvdev->virtio_cookie, mvdev);
	if (status & VIRTIO_CONFIG_S_DRIVER_OK)
	wait_for_completion(&mvdev->reset_done);
	kfree(mvdev);
	iowrite8(1, &dc->guest_ack);
	dev_dbg(mdrv->dev, "%s %d guest_ack %d\n",
	__func__, __LINE__, ioread8(&dc->guest_ack));
	ret = 0;
	}

	return ret;
	}

	#define REMOVE_DEVICES true

	static void mic_scan_devices(struct mic_driver *mdrv, bool remove)
	{
	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 += mic_total_desc_size(d)) {
	d = mdrv->dp + i;
	dc = (void __iomem *)d + mic_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(mdrv->dev, (void __force *)d,
	mic_match_desc);
	if (dev) {
	if (remove)
	iowrite8(MIC_VIRTIO_PARAM_DEV_REMOVE,
	&dc->config_change);
	put_device(dev);
	mic_handle_config_change(d, i, mdrv);
	ret = mic_remove_device(d, i, mdrv);
	if (!ret && !remove)
	iowrite8(-1, &d->type);
	if (remove) {
	iowrite8(0, &dc->config_change);
	iowrite8(0, &dc->guest_ack);
	}
	continue;
	}

	/* new device */
	dev_dbg(mdrv->dev, "%s %d Adding new virtio device %p\n",
	__func__, __LINE__, d);
	if (!remove)
	mic_add_device(d, i, mdrv);
	}
	}

	/*
	* mic_hotplug_device tries to find changes in the device page.
	*/
	static void mic_hotplug_devices(struct work_struct *work)
	{
	struct mic_driver *mdrv = container_of(work,
	struct mic_driver, hotplug_work);

	mic_scan_devices(mdrv, !REMOVE_DEVICES);
	}

	/*
	* Interrupt handler for hot plug/config changes etc.
	*/
	static irqreturn_t
	mic_extint_handler(int irq, void *data)
	{
	struct mic_driver mdrv = (struct mic_driver )data;

	dev_dbg(mdrv->dev, "%s %d hotplug work\n",
	__func__, __LINE__);
	mic_ack_interrupt(&mdrv->mdev);
	schedule_work(&mdrv->hotplug_work);
	return IRQ_HANDLED;
	}

	/*
	* Init function for virtio
	*/
	int mic_devices_init(struct mic_driver *mdrv)
	{
	int rc;
	struct mic_bootparam __iomem *bootparam;
	int config_db;

	INIT_WORK(&mdrv->hotplug_work, mic_hotplug_devices);
	mic_scan_devices(mdrv, !REMOVE_DEVICES);

	config_db = mic_next_card_db();
	virtio_config_cookie = mic_request_card_irq(mic_extint_handler,
	"virtio_config_intr", mdrv, config_db);
	if (IS_ERR(virtio_config_cookie)) {
	rc = PTR_ERR(virtio_config_cookie);
	goto exit;
	}

	bootparam = mdrv->dp;
	iowrite8(config_db, &bootparam->h2c_config_db);
	return 0;
	exit:
	return rc;
	}

	/*
	* Uninit function for virtio
	*/
	void mic_devices_uninit(struct mic_driver *mdrv)
	{
	struct mic_bootparam __iomem *bootparam = mdrv->dp;
	iowrite8(-1, &bootparam->h2c_config_db);
	mic_free_card_irq(virtio_config_cookie, mdrv);
	flush_work(&mdrv->hotplug_work);
	mic_scan_devices(mdrv, REMOVE_DEVICES);
	}