1 files changed, 786 insertions, 0 deletions

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
new file mode 100644
index 00000000000..0c048dd8013
--- /dev/null
+++ b/drivers/hv/vmbus_drv.c
@@ -0,0 +1,786 @@
+/*
+ * Copyright (c) 2009, Microsoft Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * You should have received a copy of the GNU General Public License along with
+ * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
+ * Place - Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * Authors:
+ *   Haiyang Zhang <haiyangz@microsoft.com>
+ *   Hank Janssen  <hjanssen@microsoft.com>
+ *   K. Y. Srinivasan <kys@microsoft.com>
+ *
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/sysctl.h>
+#include <linux/slab.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
+#include <linux/completion.h>
+#include <linux/hyperv.h>
+#include <asm/hyperv.h>
+#include "hyperv_vmbus.h"
+
+
+static struct acpi_device  *hv_acpi_dev;
+
+static struct tasklet_struct msg_dpc;
+static struct tasklet_struct event_dpc;
+static struct completion probe_event;
+static int irq;
+
+struct hv_device_info {
+	u32 chn_id;
+	u32 chn_state;
+	uuid_le chn_type;
+	uuid_le chn_instance;
+
+	u32 monitor_id;
+	u32 server_monitor_pending;
+	u32 server_monitor_latency;
+	u32 server_monitor_conn_id;
+	u32 client_monitor_pending;
+	u32 client_monitor_latency;
+	u32 client_monitor_conn_id;
+
+	struct hv_dev_port_info inbound;
+	struct hv_dev_port_info outbound;
+};
+
+
+static void get_channel_info(struct hv_device *device,
+			     struct hv_device_info *info)
+{
+	struct vmbus_channel_debug_info debug_info;
+
+	if (!device->channel)
+		return;
+
+	vmbus_get_debug_info(device->channel, &debug_info);
+
+	info->chn_id = debug_info.relid;
+	info->chn_state = debug_info.state;
+	memcpy(&info->chn_type, &debug_info.interfacetype,
+	       sizeof(uuid_le));
+	memcpy(&info->chn_instance, &debug_info.interface_instance,
+	       sizeof(uuid_le));
+
+	info->monitor_id = debug_info.monitorid;
+
+	info->server_monitor_pending = debug_info.servermonitor_pending;
+	info->server_monitor_latency = debug_info.servermonitor_latency;
+	info->server_monitor_conn_id = debug_info.servermonitor_connectionid;
+
+	info->client_monitor_pending = debug_info.clientmonitor_pending;
+	info->client_monitor_latency = debug_info.clientmonitor_latency;
+	info->client_monitor_conn_id = debug_info.clientmonitor_connectionid;
+
+	info->inbound.int_mask = debug_info.inbound.current_interrupt_mask;
+	info->inbound.read_idx = debug_info.inbound.current_read_index;
+	info->inbound.write_idx = debug_info.inbound.current_write_index;
+	info->inbound.bytes_avail_toread =
+		debug_info.inbound.bytes_avail_toread;
+	info->inbound.bytes_avail_towrite =
+		debug_info.inbound.bytes_avail_towrite;
+
+	info->outbound.int_mask =
+		debug_info.outbound.current_interrupt_mask;
+	info->outbound.read_idx = debug_info.outbound.current_read_index;
+	info->outbound.write_idx = debug_info.outbound.current_write_index;
+	info->outbound.bytes_avail_toread =
+		debug_info.outbound.bytes_avail_toread;
+	info->outbound.bytes_avail_towrite =
+		debug_info.outbound.bytes_avail_towrite;
+}
+
+#define VMBUS_ALIAS_LEN ((sizeof((struct hv_vmbus_device_id *)0)->guid) * 2)
+static void print_alias_name(struct hv_device *hv_dev, char *alias_name)
+{
+	int i;
+	for (i = 0; i < VMBUS_ALIAS_LEN; i += 2)
+		sprintf(&alias_name[i], "%02x", hv_dev->dev_type.b[i/2]);
+}
+
+/*
+ * vmbus_show_device_attr - Show the device attribute in sysfs.
+ *
+ * This is invoked when user does a
+ * "cat /sys/bus/vmbus/devices/<busdevice>/<attr name>"
+ */
+static ssize_t vmbus_show_device_attr(struct device *dev,
+				      struct device_attribute *dev_attr,
+				      char *buf)
+{
+	struct hv_device *hv_dev = device_to_hv_device(dev);
+	struct hv_device_info *device_info;
+	char alias_name[VMBUS_ALIAS_LEN + 1];
+	int ret = 0;
+
+	device_info = kzalloc(sizeof(struct hv_device_info), GFP_KERNEL);
+	if (!device_info)
+		return ret;
+
+	get_channel_info(hv_dev, device_info);
+
+	if (!strcmp(dev_attr->attr.name, "class_id")) {
+		ret = sprintf(buf, "{%02x%02x%02x%02x-%02x%02x-%02x%02x-"
+			       "%02x%02x%02x%02x%02x%02x%02x%02x}\n",
+			       device_info->chn_type.b[3],
+			       device_info->chn_type.b[2],
+			       device_info->chn_type.b[1],
+			       device_info->chn_type.b[0],
+			       device_info->chn_type.b[5],
+			       device_info->chn_type.b[4],
+			       device_info->chn_type.b[7],
+			       device_info->chn_type.b[6],
+			       device_info->chn_type.b[8],
+			       device_info->chn_type.b[9],
+			       device_info->chn_type.b[10],
+			       device_info->chn_type.b[11],
+			       device_info->chn_type.b[12],
+			       device_info->chn_type.b[13],
+			       device_info->chn_type.b[14],
+			       device_info->chn_type.b[15]);
+	} else if (!strcmp(dev_attr->attr.name, "device_id")) {
+		ret = sprintf(buf, "{%02x%02x%02x%02x-%02x%02x-%02x%02x-"
+			       "%02x%02x%02x%02x%02x%02x%02x%02x}\n",
+			       device_info->chn_instance.b[3],
+			       device_info->chn_instance.b[2],
+			       device_info->chn_instance.b[1],
+			       device_info->chn_instance.b[0],
+			       device_info->chn_instance.b[5],
+			       device_info->chn_instance.b[4],
+			       device_info->chn_instance.b[7],
+			       device_info->chn_instance.b[6],
+			       device_info->chn_instance.b[8],
+			       device_info->chn_instance.b[9],
+			       device_info->chn_instance.b[10],
+			       device_info->chn_instance.b[11],
+			       device_info->chn_instance.b[12],
+			       device_info->chn_instance.b[13],
+			       device_info->chn_instance.b[14],
+			       device_info->chn_instance.b[15]);
+	} else if (!strcmp(dev_attr->attr.name, "modalias")) {
+		print_alias_name(hv_dev, alias_name);
+		ret = sprintf(buf, "vmbus:%s\n", alias_name);
+	} else if (!strcmp(dev_attr->attr.name, "state")) {
+		ret = sprintf(buf, "%d\n", device_info->chn_state);
+	} else if (!strcmp(dev_attr->attr.name, "id")) {
+		ret = sprintf(buf, "%d\n", device_info->chn_id);
+	} else if (!strcmp(dev_attr->attr.name, "out_intr_mask")) {
+		ret = sprintf(buf, "%d\n", device_info->outbound.int_mask);
+	} else if (!strcmp(dev_attr->attr.name, "out_read_index")) {
+		ret = sprintf(buf, "%d\n", device_info->outbound.read_idx);
+	} else if (!strcmp(dev_attr->attr.name, "out_write_index")) {
+		ret = sprintf(buf, "%d\n", device_info->outbound.write_idx);
+	} else if (!strcmp(dev_attr->attr.name, "out_read_bytes_avail")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->outbound.bytes_avail_toread);
+	} else if (!strcmp(dev_attr->attr.name, "out_write_bytes_avail")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->outbound.bytes_avail_towrite);
+	} else if (!strcmp(dev_attr->attr.name, "in_intr_mask")) {
+		ret = sprintf(buf, "%d\n", device_info->inbound.int_mask);
+	} else if (!strcmp(dev_attr->attr.name, "in_read_index")) {
+		ret = sprintf(buf, "%d\n", device_info->inbound.read_idx);
+	} else if (!strcmp(dev_attr->attr.name, "in_write_index")) {
+		ret = sprintf(buf, "%d\n", device_info->inbound.write_idx);
+	} else if (!strcmp(dev_attr->attr.name, "in_read_bytes_avail")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->inbound.bytes_avail_toread);
+	} else if (!strcmp(dev_attr->attr.name, "in_write_bytes_avail")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->inbound.bytes_avail_towrite);
+	} else if (!strcmp(dev_attr->attr.name, "monitor_id")) {
+		ret = sprintf(buf, "%d\n", device_info->monitor_id);
+	} else if (!strcmp(dev_attr->attr.name, "server_monitor_pending")) {
+		ret = sprintf(buf, "%d\n", device_info->server_monitor_pending);
+	} else if (!strcmp(dev_attr->attr.name, "server_monitor_latency")) {
+		ret = sprintf(buf, "%d\n", device_info->server_monitor_latency);
+	} else if (!strcmp(dev_attr->attr.name, "server_monitor_conn_id")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->server_monitor_conn_id);
+	} else if (!strcmp(dev_attr->attr.name, "client_monitor_pending")) {
+		ret = sprintf(buf, "%d\n", device_info->client_monitor_pending);
+	} else if (!strcmp(dev_attr->attr.name, "client_monitor_latency")) {
+		ret = sprintf(buf, "%d\n", device_info->client_monitor_latency);
+	} else if (!strcmp(dev_attr->attr.name, "client_monitor_conn_id")) {
+		ret = sprintf(buf, "%d\n",
+			       device_info->client_monitor_conn_id);
+	}
+
+	kfree(device_info);
+	return ret;
+}
+
+/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
+static struct device_attribute vmbus_device_attrs[] = {
+	__ATTR(id, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(state, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(class_id, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(device_id, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(monitor_id, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(modalias, S_IRUGO, vmbus_show_device_attr, NULL),
+
+	__ATTR(server_monitor_pending, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(server_monitor_latency, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(server_monitor_conn_id, S_IRUGO, vmbus_show_device_attr, NULL),
+
+	__ATTR(client_monitor_pending, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(client_monitor_latency, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(client_monitor_conn_id, S_IRUGO, vmbus_show_device_attr, NULL),
+
+	__ATTR(out_intr_mask, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(out_read_index, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(out_write_index, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(out_read_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(out_write_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
+
+	__ATTR(in_intr_mask, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(in_read_index, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(in_write_index, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(in_read_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR(in_write_bytes_avail, S_IRUGO, vmbus_show_device_attr, NULL),
+	__ATTR_NULL
+};
+
+
+/*
+ * vmbus_uevent - add uevent for our device
+ *
+ * This routine is invoked when a device is added or removed on the vmbus to
+ * generate a uevent to udev in the userspace. The udev will then look at its
+ * rule and the uevent generated here to load the appropriate driver
+ *
+ * The alias string will be of the form vmbus:guid where guid is the string
+ * representation of the device guid (each byte of the guid will be
+ * represented with two hex characters.
+ */
+static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
+{
+	struct hv_device *dev = device_to_hv_device(device);
+	int ret;
+	char alias_name[VMBUS_ALIAS_LEN + 1];
+
+	print_alias_name(dev, alias_name);
+	ret = add_uevent_var(env, "MODALIAS=vmbus:%s", alias_name);
+	return ret;
+}
+
+static uuid_le null_guid;
+
+static inline bool is_null_guid(const __u8 *guid)
+{
+	if (memcmp(guid, &null_guid, sizeof(uuid_le)))
+		return false;
+	return true;
+}
+
+/*
+ * Return a matching hv_vmbus_device_id pointer.
+ * If there is no match, return NULL.
+ */
+static const struct hv_vmbus_device_id *hv_vmbus_get_id(
+					const struct hv_vmbus_device_id *id,
+					__u8 *guid)
+{
+	for (; !is_null_guid(id->guid); id++)
+		if (!memcmp(&id->guid, guid, sizeof(uuid_le)))
+			return id;
+
+	return NULL;
+}
+
+
+
+/*
+ * vmbus_match - Attempt to match the specified device to the specified driver
+ */
+static int vmbus_match(struct device *device, struct device_driver *driver)
+{
+	struct hv_driver *drv = drv_to_hv_drv(driver);
+	struct hv_device *hv_dev = device_to_hv_device(device);
+
+	if (hv_vmbus_get_id(drv->id_table, hv_dev->dev_type.b))
+		return 1;
+
+	return 0;
+}
+
+/*
+ * vmbus_probe - Add the new vmbus's child device
+ */
+static int vmbus_probe(struct device *child_device)
+{
+	int ret = 0;
+	struct hv_driver *drv =
+			drv_to_hv_drv(child_device->driver);
+	struct hv_device *dev = device_to_hv_device(child_device);
+	const struct hv_vmbus_device_id *dev_id;
+
+	dev_id = hv_vmbus_get_id(drv->id_table, dev->dev_type.b);
+	if (drv->probe) {
+		ret = drv->probe(dev, dev_id);
+		if (ret != 0)
+			pr_err("probe failed for device %s (%d)\n",
+			       dev_name(child_device), ret);
+
+	} else {
+		pr_err("probe not set for driver %s\n",
+		       dev_name(child_device));
+		ret = -ENODEV;
+	}
+	return ret;
+}
+
+/*
+ * vmbus_remove - Remove a vmbus device
+ */
+static int vmbus_remove(struct device *child_device)
+{
+	struct hv_driver *drv = drv_to_hv_drv(child_device->driver);
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+	if (drv->remove)
+		drv->remove(dev);
+	else
+		pr_err("remove not set for driver %s\n",
+			dev_name(child_device));
+
+	return 0;
+}
+
+
+/*
+ * vmbus_shutdown - Shutdown a vmbus device
+ */
+static void vmbus_shutdown(struct device *child_device)
+{
+	struct hv_driver *drv;
+	struct hv_device *dev = device_to_hv_device(child_device);
+
+
+	/* The device may not be attached yet */
+	if (!child_device->driver)
+		return;
+
+	drv = drv_to_hv_drv(child_device->driver);
+
+	if (drv->shutdown)
+		drv->shutdown(dev);
+
+	return;
+}
+
+
+/*
+ * vmbus_device_release - Final callback release of the vmbus child device
+ */
+static void vmbus_device_release(struct device *device)
+{
+	struct hv_device *hv_dev = device_to_hv_device(device);
+
+	kfree(hv_dev);
+
+}
+
+/* The one and only one */
+static struct bus_type  hv_bus = {
+	.name =		"vmbus",
+	.match =		vmbus_match,
+	.shutdown =		vmbus_shutdown,
+	.remove =		vmbus_remove,
+	.probe =		vmbus_probe,
+	.uevent =		vmbus_uevent,
+	.dev_attrs =	vmbus_device_attrs,
+};
+
+static const char *driver_name = "hyperv";
+
+
+struct onmessage_work_context {
+	struct work_struct work;
+	struct hv_message msg;
+};
+
+static void vmbus_onmessage_work(struct work_struct *work)
+{
+	struct onmessage_work_context *ctx;
+
+	ctx = container_of(work, struct onmessage_work_context,
+			   work);
+	vmbus_onmessage(&ctx->msg);
+	kfree(ctx);
+}
+
+static void vmbus_on_msg_dpc(unsigned long data)
+{
+	int cpu = smp_processor_id();
+	void *page_addr = hv_context.synic_message_page[cpu];
+	struct hv_message *msg = (struct hv_message *)page_addr +
+				  VMBUS_MESSAGE_SINT;
+	struct onmessage_work_context *ctx;
+
+	while (1) {
+		if (msg->header.message_type == HVMSG_NONE) {
+			/* no msg */
+			break;
+		} else {
+			ctx = kmalloc(sizeof(*ctx), GFP_ATOMIC);
+			if (ctx == NULL)
+				continue;
+			INIT_WORK(&ctx->work, vmbus_onmessage_work);
+			memcpy(&ctx->msg, msg, sizeof(*msg));
+			queue_work(vmbus_connection.work_queue, &ctx->work);
+		}
+
+		msg->header.message_type = HVMSG_NONE;
+
+		/*
+		 * Make sure the write to MessageType (ie set to
+		 * HVMSG_NONE) happens before we read the
+		 * MessagePending and EOMing. Otherwise, the EOMing
+		 * will not deliver any more messages since there is
+		 * no empty slot
+		 */
+		smp_mb();
+
+		if (msg->header.message_flags.msg_pending) {
+			/*
+			 * This will cause message queue rescan to
+			 * possibly deliver another msg from the
+			 * hypervisor
+			 */
+			wrmsrl(HV_X64_MSR_EOM, 0);
+		}
+	}
+}
+
+static irqreturn_t vmbus_isr(int irq, void *dev_id)
+{
+	int cpu = smp_processor_id();
+	void *page_addr;
+	struct hv_message *msg;
+	union hv_synic_event_flags *event;
+	bool handled = false;
+
+	/*
+	 * Check for events before checking for messages. This is the order
+	 * in which events and messages are checked in Windows guests on
+	 * Hyper-V, and the Windows team suggested we do the same.
+	 */
+
+	page_addr = hv_context.synic_event_page[cpu];
+	event = (union hv_synic_event_flags *)page_addr + VMBUS_MESSAGE_SINT;
+
+	/* Since we are a child, we only need to check bit 0 */
+	if (sync_test_and_clear_bit(0, (unsigned long *) &event->flags32[0])) {
+		handled = true;
+		tasklet_schedule(&event_dpc);
+	}
+
+	page_addr = hv_context.synic_message_page[cpu];
+	msg = (struct hv_message *)page_addr + VMBUS_MESSAGE_SINT;
+
+	/* Check if there are actual msgs to be processed */
+	if (msg->header.message_type != HVMSG_NONE) {
+		handled = true;
+		tasklet_schedule(&msg_dpc);
+	}
+
+	if (handled)
+		return IRQ_HANDLED;
+	else
+		return IRQ_NONE;
+}
+
+/*
+ * vmbus_bus_init -Main vmbus driver initialization routine.
+ *
+ * Here, we
+ *	- initialize the vmbus driver context
+ *	- invoke the vmbus hv main init routine
+ *	- get the irq resource
+ *	- retrieve the channel offers
+ */
+static int vmbus_bus_init(int irq)
+{
+	int ret;
+	unsigned int vector;
+
+	/* Hypervisor initialization...setup hypercall page..etc */
+	ret = hv_init();
+	if (ret != 0) {
+		pr_err("Unable to initialize the hypervisor - 0x%x\n", ret);
+		return ret;
+	}
+
+	tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
+	tasklet_init(&event_dpc, vmbus_on_event, 0);
+
+	ret = bus_register(&hv_bus);
+	if (ret)
+		goto err_cleanup;
+
+	ret = request_irq(irq, vmbus_isr, IRQF_SAMPLE_RANDOM,
+			driver_name, hv_acpi_dev);
+
+	if (ret != 0) {
+		pr_err("Unable to request IRQ %d\n",
+			   irq);
+		goto err_unregister;
+	}
+
+	vector = IRQ0_VECTOR + irq;
+
+	/*
+	 * Notify the hypervisor of our irq and
+	 * connect to the host.
+	 */
+	on_each_cpu(hv_synic_init, (void *)&vector, 1);
+	ret = vmbus_connect();
+	if (ret)
+		goto err_irq;
+
+	vmbus_request_offers();
+
+	return 0;
+
+err_irq:
+	free_irq(irq, hv_acpi_dev);
+
+err_unregister:
+	bus_unregister(&hv_bus);
+
+err_cleanup:
+	hv_cleanup();
+
+	return ret;
+}
+
+/**
+ * __vmbus_child_driver_register - Register a vmbus's driver
+ * @drv: Pointer to driver structure you want to register
+ * @owner: owner module of the drv
+ * @mod_name: module name string
+ *
+ * Registers the given driver with Linux through the 'driver_register()' call
+ * and sets up the hyper-v vmbus handling for this driver.
+ * It will return the state of the 'driver_register()' call.
+ *
+ */
+int __vmbus_driver_register(struct hv_driver *hv_driver, struct module *owner, const char *mod_name)
+{
+	int ret;
+
+	pr_info("registering driver %s\n", hv_driver->name);
+
+	hv_driver->driver.name = hv_driver->name;
+	hv_driver->driver.owner = owner;
+	hv_driver->driver.mod_name = mod_name;
+	hv_driver->driver.bus = &hv_bus;
+
+	ret = driver_register(&hv_driver->driver);
+
+	vmbus_request_offers();
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__vmbus_driver_register);
+
+/**
+ * vmbus_driver_unregister() - Unregister a vmbus's driver
+ * @drv: Pointer to driver structure you want to un-register
+ *
+ * Un-register the given driver that was previous registered with a call to
+ * vmbus_driver_register()
+ */
+void vmbus_driver_unregister(struct hv_driver *hv_driver)
+{
+	pr_info("unregistering driver %s\n", hv_driver->name);
+
+	driver_unregister(&hv_driver->driver);
+
+}
+EXPORT_SYMBOL_GPL(vmbus_driver_unregister);
+
+/*
+ * vmbus_device_create - Creates and registers a new child device
+ * on the vmbus.
+ */
+struct hv_device *vmbus_device_create(uuid_le *type,
+					    uuid_le *instance,
+					    struct vmbus_channel *channel)
+{
+	struct hv_device *child_device_obj;
+
+	child_device_obj = kzalloc(sizeof(struct hv_device), GFP_KERNEL);
+	if (!child_device_obj) {
+		pr_err("Unable to allocate device object for child device\n");
+		return NULL;
+	}
+
+	child_device_obj->channel = channel;
+	memcpy(&child_device_obj->dev_type, type, sizeof(uuid_le));
+	memcpy(&child_device_obj->dev_instance, instance,
+	       sizeof(uuid_le));
+
+
+	return child_device_obj;
+}
+
+/*
+ * vmbus_device_register - Register the child device
+ */
+int vmbus_device_register(struct hv_device *child_device_obj)
+{
+	int ret = 0;
+
+	static atomic_t device_num = ATOMIC_INIT(0);
+
+	dev_set_name(&child_device_obj->device, "vmbus_0_%d",
+		     atomic_inc_return(&device_num));
+
+	child_device_obj->device.bus = &hv_bus;
+	child_device_obj->device.parent = &hv_acpi_dev->dev;
+	child_device_obj->device.release = vmbus_device_release;
+
+	/*
+	 * Register with the LDM. This will kick off the driver/device
+	 * binding...which will eventually call vmbus_match() and vmbus_probe()
+	 */
+	ret = device_register(&child_device_obj->device);
+
+	if (ret)
+		pr_err("Unable to register child device\n");
+	else
+		pr_info("child device %s registered\n",
+			dev_name(&child_device_obj->device));
+
+	return ret;
+}
+
+/*
+ * vmbus_device_unregister - Remove the specified child device
+ * from the vmbus.
+ */
+void vmbus_device_unregister(struct hv_device *device_obj)
+{
+	/*
+	 * Kick off the process of unregistering the device.
+	 * This will call vmbus_remove() and eventually vmbus_device_release()
+	 */
+	device_unregister(&device_obj->device);
+
+	pr_info("child device %s unregistered\n",
+		dev_name(&device_obj->device));
+}
+
+
+/*
+ * VMBUS is an acpi enumerated device. Get the the IRQ information
+ * from DSDT.
+ */
+
+static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *irq)
+{
+
+	if (res->type == ACPI_RESOURCE_TYPE_IRQ) {
+		struct acpi_resource_irq *irqp;
+		irqp = &res->data.irq;
+
+		*((unsigned int *)irq) = irqp->interrupts[0];
+	}
+
+	return AE_OK;
+}
+
+static int vmbus_acpi_add(struct acpi_device *device)
+{
+	acpi_status result;
+
+	hv_acpi_dev = device;
+
+	result = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
+					vmbus_walk_resources, &irq);
+
+	if (ACPI_FAILURE(result)) {
+		complete(&probe_event);
+		return -ENODEV;
+	}
+	complete(&probe_event);
+	return 0;
+}
+
+static const struct acpi_device_id vmbus_acpi_device_ids[] = {
+	{"VMBUS", 0},
+	{"VMBus", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
+
+static struct acpi_driver vmbus_acpi_driver = {
+	.name = "vmbus",
+	.ids = vmbus_acpi_device_ids,
+	.ops = {
+		.add = vmbus_acpi_add,
+	},
+};
+
+static int __init hv_acpi_init(void)
+{
+	int ret, t;
+
+	init_completion(&probe_event);
+
+	/*
+	 * Get irq resources first.
+	 */
+
+	ret = acpi_bus_register_driver(&vmbus_acpi_driver);
+
+	if (ret)
+		return ret;
+
+	t = wait_for_completion_timeout(&probe_event, 5*HZ);
+	if (t == 0) {
+		ret = -ETIMEDOUT;
+		goto cleanup;
+	}
+
+	if (irq <= 0) {
+		ret = -ENODEV;
+		goto cleanup;
+	}
+
+	ret = vmbus_bus_init(irq);
+	if (ret)
+		goto cleanup;
+
+	return 0;
+
+cleanup:
+	acpi_bus_unregister_driver(&vmbus_acpi_driver);
+	return ret;
+}
+
+
+MODULE_LICENSE("GPL");
+MODULE_VERSION(HV_DRV_VERSION);
+
+module_init(hv_acpi_init);