[PATCH 3/4] s390/kvm: Add a channel I/O based virtio transport driver.

[Cornelia Huck <cornelia.huck@de.ibm.com>]

Add a driver for kvm guests that matches virtual ccw devices provided
by the host as virtio bridge devices.

These virtio-ccw devices use a special set of channel commands in order
to perform virtio functions.

Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
---
 arch/s390/include/asm/irq.h   |   1 +
 arch/s390/kernel/irq.c        |   1 +
 drivers/s390/kvm/Makefile     |   2 +-
 drivers/s390/kvm/virtio_ccw.c | 761 ++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 764 insertions(+), 1 deletion(-)
 create mode 100644 drivers/s390/kvm/virtio_ccw.c

diff --git a/arch/s390/include/asm/irq.h b/arch/s390/include/asm/irq.h
index 2b9d418..b4bea53 100644
--- a/arch/s390/include/asm/irq.h
+++ b/arch/s390/include/asm/irq.h
@@ -31,6 +31,7 @@ enum interruption_class {
 	IOINT_CTC,
 	IOINT_APB,
 	IOINT_CSC,
+	IOINT_VIR,
 	NMI_NMI,
 	NR_IRQS,
 };
diff --git a/arch/s390/kernel/irq.c b/arch/s390/kernel/irq.c
index dd7630d..2cc7eed 100644
--- a/arch/s390/kernel/irq.c
+++ b/arch/s390/kernel/irq.c
@@ -56,6 +56,7 @@ static const struct irq_class intrclass_names[] = {
 	{.name = "CTC", .desc = "[I/O] CTC" },
 	{.name = "APB", .desc = "[I/O] AP Bus" },
 	{.name = "CSC", .desc = "[I/O] CHSC Subchannel" },
+	{.name = "VIR", .desc = "[I/O] Virtual I/O Devices" },
 	{.name = "NMI", .desc = "[NMI] Machine Check" },
 };
 
diff --git a/drivers/s390/kvm/Makefile b/drivers/s390/kvm/Makefile
index 0815690..241891a 100644
--- a/drivers/s390/kvm/Makefile
+++ b/drivers/s390/kvm/Makefile
@@ -6,4 +6,4 @@
 # it under the terms of the GNU General Public License (version 2 only)
 # as published by the Free Software Foundation.
 
-obj-$(CONFIG_S390_GUEST) += kvm_virtio.o
+obj-$(CONFIG_S390_GUEST) += kvm_virtio.o virtio_ccw.o
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
new file mode 100644
index 0000000..df0f994
--- /dev/null
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -0,0 +1,761 @@
+/*
+ * ccw based virtio transport
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * 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): Cornelia Huck <cornelia.huck@de.ibm.com>
+ */
+
+#include <linux/kernel_stat.h>
+#include <linux/init.h>
+#include <linux/bootmem.h>
+#include <linux/err.h>
+#include <linux/virtio.h>
+#include <linux/virtio_config.h>
+#include <linux/slab.h>
+#include <linux/virtio_console.h>
+#include <linux/interrupt.h>
+#include <linux/virtio_ring.h>
+#include <linux/pfn.h>
+#include <linux/async.h>
+#include <linux/wait.h>
+#include <linux/list.h>
+#include <linux/bitops.h>
+#include <linux/module.h>
+#include <asm/io.h>
+#include <asm/kvm_para.h>
+#include <asm/setup.h>
+#include <asm/irq.h>
+#include <asm/cio.h>
+#include <asm/ccwdev.h>
+
+/*
+ * virtio related functions
+ */
+
+struct vq_config_block {
+	__u16 index;
+	__u16 num;
+} __attribute__ ((packed));
+
+#define VIRTIO_CCW_CONFIG_SIZE 0x100
+/* same as PCI config space size, should be enough for all drivers */
+
+struct virtio_ccw_device {
+	struct virtio_device vdev;
+	__u8 status;
+	__u8 config[VIRTIO_CCW_CONFIG_SIZE];
+	struct ccw_device *cdev;
+	struct ccw1 ccw;
+	__u32 area;
+	__u32 curr_io;
+	int err;
+	wait_queue_head_t wait_q;
+	spinlock_t lock;
+	struct list_head virtqueues;
+	unsigned long indicators; /* XXX - works because we're under 64 bit */
+	struct vq_config_block *config_block;
+};
+
+struct vq_info_block {
+	__u64 queue;
+	__u16 num;
+} __attribute__ ((packed));
+
+struct virtio_ccw_vq_info {
+	struct virtqueue *vq;
+	int num;
+	int queue_index;
+	void *queue;
+	struct vq_info_block *info_block;
+	struct list_head node;
+};
+
+#define KVM_VIRTIO_CCW_RING_ALIGN 4096
+
+#define CCW_CMD_SET_VQ 0x13
+#define CCW_CMD_VDEV_RESET 0x33
+#define CCW_CMD_SET_IND 0x43
+#define CCW_CMD_READ_FEAT 0x12
+#define CCW_CMD_WRITE_FEAT 0x11
+#define CCW_CMD_READ_CONF 0x22
+#define CCW_CMD_WRITE_CONF 0x21
+#define CCW_CMD_WRITE_STATUS 0x31
+#define CCW_CMD_READ_VQ_CONF 0x32
+
+#define VIRTIO_CCW_DOING_SET_VQ 0x00010000
+#define VIRTIO_CCW_DOING_RESET 0x00040000
+#define VIRTIO_CCW_DOING_READ_FEAT 0x00080000
+#define VIRTIO_CCW_DOING_WRITE_FEAT 0x00100000
+#define VIRTIO_CCW_DOING_READ_CONFIG 0x00200000
+#define VIRTIO_CCW_DOING_WRITE_CONFIG 0x00400000
+#define VIRTIO_CCW_DOING_WRITE_STATUS 0x00800000
+#define VIRTIO_CCW_DOING_SET_IND 0x01000000
+#define VIRTIO_CCW_DOING_READ_VQ_CONF 0x02000000
+#define VIRTIO_CCW_INTPARM_MASK 0xffff0000
+
+static struct virtio_ccw_device *to_vc_device(struct virtio_device *vdev)
+{
+	return container_of(vdev, struct virtio_ccw_device, vdev);
+}
+
+static int doing_io(struct virtio_ccw_device *vcdev, __u32 flag)
+{
+	unsigned long flags;
+	__u32 ret;
+
+	spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+	if (vcdev->err)
+		ret = vcdev->err;
+	else
+		ret = vcdev->curr_io & flag;
+	spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+	return ret;
+}
+
+static int ccw_io_helper(struct virtio_ccw_device *vcdev, __u32 intparm)
+{
+	int ret;
+	unsigned long flags;
+	int flag = intparm & VIRTIO_CCW_INTPARM_MASK;
+
+	spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+	ret = ccw_device_start(vcdev->cdev, &vcdev->ccw, intparm, 0, 0);
+	if (!ret)
+		vcdev->curr_io |= flag;
+	spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+	wait_event(vcdev->wait_q, doing_io(vcdev, flag) == 0);
+	return ret ? ret : vcdev->err;
+}
+
+static void virtio_ccw_kvm_notify(struct virtqueue *vq)
+{
+	struct virtio_ccw_vq_info *info = vq->priv;
+	struct virtio_ccw_device *vcdev;
+	struct subchannel_id schid;
+	__u32 reg2;
+
+	vcdev = to_vc_device(info->vq->vdev);
+	ccw_device_get_schid(vcdev->cdev, &schid);
+	reg2 = *(__u32 *)&schid;
+	kvm_hypercall2(3 /* CCW_NOTIFY */, reg2, info->queue_index);
+}
+
+static int virtio_ccw_read_vq_conf(struct virtio_ccw_device *vcdev, int index)
+{
+	vcdev->config_block->index = index;
+	vcdev->ccw.cmd_code = CCW_CMD_READ_VQ_CONF;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(struct vq_config_block);
+	vcdev->ccw.cda = (__u32)(unsigned long)(vcdev->config_block);
+	ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_VQ_CONF);
+	return vcdev->config_block->num;
+}
+
+static void virtio_ccw_del_vq(struct virtqueue *vq)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vq->vdev);
+	struct virtio_ccw_vq_info *info = vq->priv;
+	unsigned long flags;
+	unsigned long size;
+	int ret;
+
+	/* Remove from our list. */
+	spin_lock_irqsave(&vcdev->lock, flags);
+	list_del(&info->node);
+	spin_unlock_irqrestore(&vcdev->lock, flags);
+
+	/* Release from host. */
+	info->info_block->queue = 0;
+	info->info_block->num = info->queue_index;
+	vcdev->ccw.cmd_code = CCW_CMD_SET_VQ;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(*info->info_block);
+	vcdev->ccw.cda = (__u32)(unsigned long)(info->info_block);
+	ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_VQ | info->queue_index);
+	if (ret)
+		dev_warn(&vq->vdev->dev, "Error %x while deleting queue %d",
+			 ret, info->queue_index);
+
+	vring_del_virtqueue(vq);
+	size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
+	free_pages_exact(info->queue, size);
+	kfree(info->info_block);
+	kfree(info);
+}
+
+static void virtio_ccw_del_vqs(struct virtio_device *vdev)
+{
+	struct virtqueue *vq, *n;
+
+	list_for_each_entry_safe(vq, n, &vdev->vqs, list)
+		virtio_ccw_del_vq(vq);
+}
+
+static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev,
+					     int i, vq_callback_t *callback,
+					     const char *name)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+	int err;
+	struct virtqueue *vq;
+	struct virtio_ccw_vq_info *info;
+	unsigned long size;
+	unsigned long flags;
+
+	/* Allocate queue. */
+	info = kzalloc(sizeof(struct virtio_ccw_vq_info), GFP_KERNEL);
+	if (!info) {
+		dev_warn(&vcdev->cdev->dev, "no info\n");
+		err = -ENOMEM;
+		goto out_err;
+	}
+	info->info_block = kzalloc(sizeof(*info->info_block),
+				   GFP_DMA | GFP_KERNEL);
+	if (!info->info_block) {
+		dev_warn(&vcdev->cdev->dev, "no info block\n");
+		err = -ENOMEM;
+		goto out_err;
+	}
+	info->queue_index = i;
+	info->num = virtio_ccw_read_vq_conf(vcdev, i);
+	size = PAGE_ALIGN(vring_size(info->num, KVM_VIRTIO_CCW_RING_ALIGN));
+	info->queue = alloc_pages_exact(size, GFP_KERNEL | __GFP_ZERO);
+	if (info->queue == NULL) {
+		dev_warn(&vcdev->cdev->dev, "no queue\n");
+		err = -ENOMEM;
+		goto out_err;
+	}
+	vq = vring_new_virtqueue(info->num, KVM_VIRTIO_CCW_RING_ALIGN, vdev,
+				 true, info->queue, virtio_ccw_kvm_notify,
+				 callback, name);
+	if (!vq) {
+		dev_warn(&vcdev->cdev->dev, "no vq\n");
+		err = -ENOMEM;
+		free_pages_exact(info->queue, size);
+		goto out_err;
+	}
+	info->vq = vq;
+	vq->priv = info;
+
+	/* Register it with the host. */
+	info->info_block->queue = (__u64)info->queue;
+	info->info_block->num = info->queue_index;
+	vcdev->ccw.cmd_code = CCW_CMD_SET_VQ;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(*info->info_block);
+	vcdev->ccw.cda = (__u32)(unsigned long)(info->info_block);
+	err = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_VQ | info->queue_index);
+	if (err) {
+		dev_warn(&vcdev->cdev->dev, "SET_VQ failed\n");
+		free_pages_exact(info->queue, size);
+		info->vq = NULL;
+		vq->priv = NULL;
+		goto out_err;
+	}
+
+	/* Save it to our list. */
+	spin_lock_irqsave(&vcdev->lock, flags);
+	list_add(&info->node, &vcdev->virtqueues);
+	spin_unlock_irqrestore(&vcdev->lock, flags);
+
+	return vq;
+
+out_err:
+	if (info)
+		kfree(info->info_block);
+	kfree(info);
+	return ERR_PTR(err);
+}
+
+static int virtio_ccw_find_vqs(struct virtio_device *vdev, unsigned nvqs,
+			       struct virtqueue *vqs[],
+			       vq_callback_t *callbacks[],
+			       const char *names[])
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+	int ret, i;
+
+	for (i = 0; i < nvqs; ++i) {
+		vqs[i] = virtio_ccw_setup_vq(vdev, i, callbacks[i], names[i]);
+		if (IS_ERR(vqs[i])) {
+			ret = PTR_ERR(vqs[i]);
+			vqs[i] = NULL;
+			goto out;
+		}
+	}
+	/* Register queue indicators with host. */
+	vcdev->indicators = 0;
+	vcdev->ccw.cmd_code = CCW_CMD_SET_IND;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(vcdev->indicators);
+	vcdev->ccw.cda = (__u32)(unsigned long)(&vcdev->indicators);
+	ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_SET_IND);
+	if (ret)
+		goto out;
+	return 0;
+out:
+	virtio_ccw_del_vqs(vdev);
+	return ret;
+}
+
+static void virtio_ccw_reset(struct virtio_device *vdev)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	/* Send a reset ccw on device. */
+	vcdev->ccw.cmd_code = CCW_CMD_VDEV_RESET;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = 0;
+	vcdev->ccw.cda = 0;
+	ccw_io_helper(vcdev, VIRTIO_CCW_DOING_RESET);
+}
+
+static u32 virtio_ccw_get_features(struct virtio_device *vdev)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+	u32 features;
+	int ret;
+
+	/* Read the feature bits from the host. */
+	vcdev->ccw.cmd_code = CCW_CMD_READ_FEAT;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(features);
+	vcdev->ccw.cda = vcdev->area;
+	ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_FEAT);
+	if (ret)
+		return 0;
+
+	memcpy(&features, (void *)(unsigned long)vcdev->area,
+	       sizeof(features));
+	return le32_to_cpu(features);
+}
+
+static void virtio_ccw_finalize_features(struct virtio_device *vdev)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	/* Give virtio_ring a chance to accept features. */
+	vring_transport_features(vdev);
+
+	memcpy((void *)(unsigned long)vcdev->area, vdev->features,
+	       sizeof(*vdev->features));
+	/* Write the feature bits to the host. */
+	vcdev->ccw.cmd_code = CCW_CMD_WRITE_FEAT;
+	/* Sigh. The kernel's features may be longer than the host's. */
+	vcdev->ccw.flags = CCW_FLAG_SLI;
+	vcdev->ccw.count = sizeof(*vdev->features);
+	vcdev->ccw.cda = vcdev->area;
+	ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_FEAT);
+}
+
+static void virtio_ccw_get_config(struct virtio_device *vdev,
+				  unsigned int offset, void *buf, unsigned len)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+	int ret;
+
+	/* Read the config area from the host. */
+	vcdev->ccw.cmd_code = CCW_CMD_READ_CONF;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = offset + len;
+	vcdev->ccw.cda = vcdev->area;
+	ret = ccw_io_helper(vcdev, VIRTIO_CCW_DOING_READ_CONFIG);
+	if (ret)
+		return;
+
+	memcpy(vcdev->config, (void *)(unsigned long)vcdev->area,
+	       sizeof(vcdev->config));
+	memcpy(buf, &vcdev->config[offset], len);
+}
+
+static void virtio_ccw_set_config(struct virtio_device *vdev,
+				  unsigned int offset, const void *buf,
+				  unsigned len)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	memcpy(&vcdev->config[offset], buf, len);
+	/* Write the config area to the host. */
+	memcpy((void *)(unsigned long)vcdev->area, vcdev->config,
+	       sizeof(vcdev->config));
+	vcdev->ccw.cmd_code = CCW_CMD_WRITE_CONF;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = offset + len;
+	vcdev->ccw.cda = vcdev->area;
+	ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_CONFIG);
+}
+
+static u8 virtio_ccw_get_status(struct virtio_device *vdev)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	return vcdev->status;
+}
+
+static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status)
+{
+	struct virtio_ccw_device *vcdev = to_vc_device(vdev);
+
+	/* Write the status to the host. */
+	vcdev->status = status;
+	memcpy((void *)(unsigned long)vcdev->area, &status, sizeof(status));
+	vcdev->ccw.cmd_code = CCW_CMD_WRITE_STATUS;
+	vcdev->ccw.flags = 0;
+	vcdev->ccw.count = sizeof(status);
+	vcdev->ccw.cda = vcdev->area;
+	ccw_io_helper(vcdev, VIRTIO_CCW_DOING_WRITE_STATUS);
+}
+
+static struct virtio_config_ops virtio_ccw_config_ops = {
+	.get_features = virtio_ccw_get_features,
+	.finalize_features = virtio_ccw_finalize_features,
+	.get = virtio_ccw_get_config,
+	.set = virtio_ccw_set_config,
+	.get_status = virtio_ccw_get_status,
+	.set_status = virtio_ccw_set_status,
+	.reset = virtio_ccw_reset,
+	.find_vqs = virtio_ccw_find_vqs,
+	.del_vqs = virtio_ccw_del_vqs,
+};
+
+
+/*
+ * ccw bus driver related functions
+ */
+
+static void virtio_ccw_release_dev(struct device *_d)
+{
+	struct virtio_device *dev = container_of(_d, struct virtio_device,
+						 dev);
+	struct virtio_ccw_device *vcdev = to_vc_device(dev);
+
+	kfree((void *)(unsigned long)vcdev->area);
+	kfree(vcdev->config_block);
+	kfree(vcdev);
+}
+
+static int irb_is_error(struct irb *irb)
+{
+	if (scsw_cstat(&irb->scsw) != 0)
+		return 1;
+	if (scsw_dstat(&irb->scsw) & ~(DEV_STAT_CHN_END | DEV_STAT_DEV_END))
+		return 1;
+	if (scsw_cc(&irb->scsw) != 0)
+		return 1;
+	return 0;
+}
+
+static struct virtqueue *virtio_ccw_vq_by_ind(struct virtio_ccw_device *vcdev,
+					      int index)
+{
+	struct virtio_ccw_vq_info *info;
+	unsigned long flags;
+	struct virtqueue *vq;
+
+	vq = NULL;
+	spin_lock_irqsave(&vcdev->lock, flags);
+	list_for_each_entry(info, &vcdev->virtqueues, node) {
+		if (info->queue_index == index) {
+			vq = info->vq;
+			break;
+		}
+	}
+	spin_unlock_irqrestore(&vcdev->lock, flags);
+	return vq;
+}
+
+static void virtio_ccw_int_handler(struct ccw_device *cdev,
+				   unsigned long intparm,
+				   struct irb *irb)
+{
+	__u32 activity = intparm & VIRTIO_CCW_INTPARM_MASK;
+	struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+	int i;
+	struct virtqueue *vq;
+
+	/* Check if it's a notification from the host. */
+	if ((intparm == 0) &&
+	    (scsw_stctl(&irb->scsw) ==
+	     (SCSW_STCTL_ALERT_STATUS | SCSW_STCTL_STATUS_PEND))) {
+		/* OK */
+	}
+	if (irb_is_error(irb))
+		vcdev->err = -EIO; /* XXX - use real error */
+	if (vcdev->curr_io & activity) {
+		switch (activity) {
+		case VIRTIO_CCW_DOING_READ_FEAT:
+		case VIRTIO_CCW_DOING_WRITE_FEAT:
+		case VIRTIO_CCW_DOING_READ_CONFIG:
+		case VIRTIO_CCW_DOING_WRITE_CONFIG:
+		case VIRTIO_CCW_DOING_WRITE_STATUS:
+		case VIRTIO_CCW_DOING_SET_VQ:
+		case VIRTIO_CCW_DOING_SET_IND:
+		case VIRTIO_CCW_DOING_RESET:
+		case VIRTIO_CCW_DOING_READ_VQ_CONF:
+			vcdev->curr_io &= ~activity;
+			wake_up(&vcdev->wait_q);
+			break;
+		default:
+			/* don't know what to do... */
+			dev_warn(&cdev->dev, "Suspicious activity '%08x'\n",
+				 activity);
+			WARN_ON(1);
+			break;
+		}
+	}
+	for_each_set_bit(i, &vcdev->indicators,
+			 sizeof(vcdev->indicators)) {
+		vq = virtio_ccw_vq_by_ind(vcdev, i);
+		vring_interrupt(0, vq);
+		clear_bit(i, &vcdev->indicators);
+	}
+}
+
+/*
+ * We usually want to autoonline all devices, but give the admin
+ * a way to exempt devices from this.
+ */
+#define __DEV_WORDS ((__MAX_SUBCHANNEL + (8*sizeof(long) - 1)) / \
+		     (8*sizeof(long)))
+static unsigned long devs_no_auto[__MAX_SSID + 1][__DEV_WORDS];
+
+static char *no_auto = "";
+
+module_param(no_auto, charp, 0444);
+MODULE_PARM_DESC(no_auto, "list of ccw bus id ranges not to be auto-onlined");
+
+static int virtio_ccw_check_autoonline(struct ccw_device *cdev)
+{
+	struct ccw_dev_id id;
+
+	ccw_device_get_id(cdev, &id);
+	if (test_bit(id.devno, devs_no_auto[id.ssid]))
+		return 0;
+	return 1;
+}
+
+static void virtio_ccw_auto_online(void *data, async_cookie_t cookie)
+{
+	struct ccw_device *cdev = data;
+	int ret;
+
+	ret = ccw_device_set_online(cdev);
+	if (ret)
+		dev_warn(&cdev->dev, "Failed to set online: %d\n", ret);
+}
+
+static int virtio_ccw_probe(struct ccw_device *cdev)
+{
+	cdev->handler = virtio_ccw_int_handler;
+
+	if (virtio_ccw_check_autoonline(cdev))
+		async_schedule(virtio_ccw_auto_online, cdev);
+	return 0;
+}
+
+static void virtio_ccw_remove(struct ccw_device *cdev)
+{
+	cdev->handler = NULL;
+}
+
+static int virtio_ccw_offline(struct ccw_device *cdev)
+{
+	struct virtio_ccw_device *vcdev = dev_get_drvdata(&cdev->dev);
+
+	unregister_virtio_device(&vcdev->vdev);
+	dev_set_drvdata(&cdev->dev, NULL);
+	return 0;
+}
+
+
+/* Area needs to be big enough to fit status, features or configuration. */
+#define VIRTIO_AREA_SIZE VIRTIO_CCW_CONFIG_SIZE /* biggest possible use */
+
+static int virtio_ccw_online(struct ccw_device *cdev)
+{
+	int ret;
+	struct virtio_ccw_device *vcdev;
+
+	vcdev = kzalloc(sizeof(*vcdev), GFP_KERNEL);
+	if (!vcdev) {
+		dev_warn(&cdev->dev, "Could not get memory for virtio\n");
+		ret = -ENOMEM;
+		goto out_free;
+	}
+	vcdev->area = (__u32)(unsigned long)kzalloc(VIRTIO_AREA_SIZE,
+						    GFP_DMA | GFP_KERNEL);
+	if (!vcdev->area) {
+		dev_warn(&cdev->dev, "Cound not get memory for virtio\n");
+		ret = -ENOMEM;
+		goto out_free;
+	}
+	vcdev->config_block = kzalloc(sizeof(*vcdev->config_block),
+				   GFP_DMA | GFP_KERNEL);
+	if (!vcdev->config_block) {
+		ret = -ENOMEM;
+		goto out_free;
+	}
+	vcdev->vdev.dev.parent = &cdev->dev;
+	vcdev->vdev.dev.release = virtio_ccw_release_dev;
+	vcdev->vdev.config = &virtio_ccw_config_ops;
+	vcdev->cdev = cdev;
+	init_waitqueue_head(&vcdev->wait_q);
+	INIT_LIST_HEAD(&vcdev->virtqueues);
+
+	dev_set_drvdata(&cdev->dev, vcdev);
+	vcdev->vdev.id.vendor = cdev->id.cu_type;
+	vcdev->vdev.id.device = cdev->id.cu_model;
+	ret = register_virtio_device(&vcdev->vdev);
+	if (ret) {
+		dev_warn(&cdev->dev, "Failed to register virtio device: %d\n",
+			 ret);
+		goto out_put;
+	}
+	return 0;
+out_put:
+	dev_set_drvdata(&cdev->dev, NULL);
+	put_device(&vcdev->vdev.dev);
+	return ret;
+out_free:
+	if (vcdev) {
+		kfree((void *)(unsigned long)vcdev->area);
+		kfree(vcdev->config_block);
+	}
+	kfree(vcdev);
+	return ret;
+}
+
+static int virtio_ccw_cio_notify(struct ccw_device *cdev, int event)
+{
+	/* TODO: Check whether we need special handling here. */
+	return 0;
+}
+
+static struct ccw_device_id virtio_ids[] = {
+	{ CCW_DEVICE(0x3832, 0) },
+	{},
+};
+MODULE_DEVICE_TABLE(ccw, virtio_ids);
+
+static struct ccw_driver virtio_ccw_driver = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name = "virtio_ccw",
+	},
+	.ids = virtio_ids,
+	.probe = virtio_ccw_probe,
+	.remove = virtio_ccw_remove,
+	.set_offline = virtio_ccw_offline,
+	.set_online = virtio_ccw_online,
+	.notify = virtio_ccw_cio_notify,
+	.int_class = IOINT_VIR,
+};
+
+static int __init pure_hex(char **cp, unsigned int *val, int min_digit,
+			   int max_digit, int max_val)
+{
+	int diff;
+
+	diff = 0;
+	*val = 0;
+
+	while (diff <= max_digit) {
+		int value = hex_to_bin(**cp);
+
+		if (value < 0)
+			break;
+		*val = *val * 16 + value;
+		(*cp)++;
+		diff++;
+	}
+
+	if ((diff < min_digit) || (diff > max_digit) || (*val > max_val))
+		return 1;
+
+	return 0;
+}
+
+static int __init parse_busid(char *str, unsigned int *cssid,
+			      unsigned int *ssid, unsigned int *devno)
+{
+	char *str_work;
+	int rc, ret;
+
+	rc = 1;
+
+	if (*str == '\0')
+		goto out;
+
+	str_work = str;
+	ret = pure_hex(&str_work, cssid, 1, 2, __MAX_CSSID);
+	if (ret || (str_work[0] != '.'))
+		goto out;
+	str_work++;
+	ret = pure_hex(&str_work, ssid, 1, 1, __MAX_SSID);
+	if (ret || (str_work[0] != '.'))
+		goto out;
+	str_work++;
+	ret = pure_hex(&str_work, devno, 4, 4, __MAX_SUBCHANNEL);
+	if (ret || (str_work[0] != '\0'))
+		goto out;
+
+	rc = 0;
+out:
+	return rc;
+}
+
+static void __init no_auto_parse(void)
+{
+	unsigned int from_cssid, to_cssid, from_ssid, to_ssid, from, to;
+	char *parm, *str;
+	int rc;
+
+	str = no_auto;
+	while ((parm = strsep(&str, ","))) {
+		rc = parse_busid(strsep(&parm, "-"), &from_cssid,
+				 &from_ssid, &from);
+		if (rc)
+			continue;
+		if (parm != NULL) {
+			rc = parse_busid(parm, &to_cssid,
+					 &to_ssid, &to);
+			if ((from_ssid > to_ssid) ||
+			    ((from_ssid == to_ssid) && (from > to)))
+				rc = -EINVAL;
+		} else {
+			to_cssid = from_cssid;
+			to_ssid = from_ssid;
+			to = from;
+		}
+		if (rc)
+			continue;
+		while ((from_ssid < to_ssid) ||
+		       ((from_ssid == to_ssid) && (from <= to))) {
+			set_bit(from, devs_no_auto[from_ssid]);
+			from++;
+			if (from > __MAX_SUBCHANNEL) {
+				from_ssid++;
+				from = 0;
+			}
+		}
+	}
+}
+
+static int __init virtio_ccw_init(void)
+{
+	/* parse no_auto string before we do anything further */
+	no_auto_parse();
+	return ccw_driver_register(&virtio_ccw_driver);
+}
+module_init(virtio_ccw_init);
+
+static void __exit virtio_ccw_exit(void)
+{
+	ccw_driver_unregister(&virtio_ccw_driver);
+}
+module_exit(virtio_ccw_exit);
-- 
1.7.11.4