/*
 * 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>
 */
#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/pci.h>
#include <linux/dmi.h>
#include "osd.h"
#include "logging.h"
#include "vmbus.h"


/* FIXME! We need to do this dynamically for PIC and APIC system */
#define VMBUS_IRQ		0x5
#define VMBUS_IRQ_VECTOR	IRQ5_VECTOR

/* Main vmbus driver data structure */
struct vmbus_driver_context {
	/* !! These must be the first 2 fields !! */
	/* FIXME, this is a bug */
	/* The driver field is not used in here. Instead, the bus field is */
	/* used to represent the driver */
	struct driver_context drv_ctx;
	struct vmbus_driver drv_obj;

	struct bus_type bus;
	struct tasklet_struct msg_dpc;
	struct tasklet_struct event_dpc;

	/* The bus root device */
	struct device_context device_ctx;
};

static int vmbus_match(struct device *device, struct device_driver *driver);
static int vmbus_probe(struct device *device);
static int vmbus_remove(struct device *device);
static void vmbus_shutdown(struct device *device);
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env);
static void vmbus_msg_dpc(unsigned long data);
static void vmbus_event_dpc(unsigned long data);

static irqreturn_t vmbus_isr(int irq, void *dev_id);

static void vmbus_device_release(struct device *device);
static void vmbus_bus_release(struct device *device);

static struct hv_device *vmbus_child_device_create(struct hv_guid *type,
						   struct hv_guid *instance,
						   void *context);
static void vmbus_child_device_destroy(struct hv_device *device_obj);
static int vmbus_child_device_register(struct hv_device *root_device_obj,
				       struct hv_device *child_device_obj);
static void vmbus_child_device_unregister(struct hv_device *child_device_obj);
static void vmbus_child_device_get_info(struct hv_device *device_obj,
					struct hv_device_info *device_info);
static ssize_t vmbus_show_device_attr(struct device *dev,
				      struct device_attribute *dev_attr,
				      char *buf);


unsigned int vmbus_loglevel = (ALL_MODULES << 16 | INFO_LVL);
EXPORT_SYMBOL(vmbus_loglevel);
	/* (ALL_MODULES << 16 | DEBUG_LVL_ENTEREXIT); */
	/* (((VMBUS | VMBUS_DRV)<<16) | DEBUG_LVL_ENTEREXIT); */

static int vmbus_irq = VMBUS_IRQ;

/* 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(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
};

/* The one and only one */
static struct vmbus_driver_context g_vmbus_drv = {
	.bus.name =		"vmbus",
	.bus.match =		vmbus_match,
	.bus.shutdown =		vmbus_shutdown,
	.bus.remove =		vmbus_remove,
	.bus.probe =		vmbus_probe,
	.bus.uevent =		vmbus_uevent,
	.bus.dev_attrs =	vmbus_device_attrs,
};

/**
 * 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 device_context *device_ctx = device_to_device_context(dev);
	struct hv_device_info device_info;

	memset(&device_info, 0, sizeof(struct hv_device_info));

	vmbus_child_device_get_info(&device_ctx->device_obj, &device_info);

	if (!strcmp(dev_attr->attr.name, "class_id")) {
		return sprintf(buf, "{%02x%02x%02x%02x-%02x%02x-%02x%02x-"
			       "%02x%02x%02x%02x%02x%02x%02x%02x}\n",
			       device_info.ChannelType.data[3],
			       device_info.ChannelType.data[2],
			       device_info.ChannelType.data[1],
			       device_info.ChannelType.data[0],
			       device_info.ChannelType.data[5],
			       device_info.ChannelType.data[4],
			       device_info.ChannelType.data[7],
			       device_info.ChannelType.data[6],
			       device_info.ChannelType.data[8],
			       device_info.ChannelType.data[9],
			       device_info.ChannelType.data[10],
			       device_info.ChannelType.data[11],
			       device_info.ChannelType.data[12],
			       device_info.ChannelType.data[13],
			       device_info.ChannelType.data[14],
			       device_info.ChannelType.data[15]);
	} else if (!strcmp(dev_attr->attr.name, "device_id")) {
		return sprintf(buf, "{%02x%02x%02x%02x-%02x%02x-%02x%02x-"
			       "%02x%02x%02x%02x%02x%02x%02x%02x}\n",
			       device_info.ChannelInstance.data[3],
			       device_info.ChannelInstance.data[2],
			       device_info.ChannelInstance.data[1],
			       device_info.ChannelInstance.data[0],
			       device_info.ChannelInstance.data[5],
			       device_info.ChannelInstance.data[4],
			       device_info.ChannelInstance.data[7],
			       device_info.ChannelInstance.data[6],
			       device_info.ChannelInstance.data[8],
			       device_info.ChannelInstance.data[9],
			       device_info.ChannelInstance.data[10],
			       device_info.ChannelInstance.data[11],
			       device_info.ChannelInstance.data[12],
			       device_info.ChannelInstance.data[13],
			       device_info.ChannelInstance.data[14],
			       device_info.ChannelInstance.data[15]);
	} else if (!strcmp(dev_attr->attr.name, "state")) {
		return sprintf(buf, "%d\n", device_info.ChannelState);
	} else if (!strcmp(dev_attr->attr.name, "id")) {
		return sprintf(buf, "%d\n", device_info.ChannelId);
	} else if (!strcmp(dev_attr->attr.name, "out_intr_mask")) {
		return sprintf(buf, "%d\n", device_info.Outbound.InterruptMask);
	} else if (!strcmp(dev_attr->attr.name, "out_read_index")) {
		return sprintf(buf, "%d\n", device_info.Outbound.ReadIndex);
	} else if (!strcmp(dev_attr->attr.name, "out_write_index")) {
		return sprintf(buf, "%d\n", device_info.Outbound.WriteIndex);
	} else if (!strcmp(dev_attr->attr.name, "out_read_bytes_avail")) {
		return sprintf(buf, "%d\n",
			       device_info.Outbound.BytesAvailToRead);
	} else if (!strcmp(dev_attr->attr.name, "out_write_bytes_avail")) {
		return sprintf(buf, "%d\n",
			       device_info.Outbound.BytesAvailToWrite);
	} else if (!strcmp(dev_attr->attr.name, "in_intr_mask")) {
		return sprintf(buf, "%d\n", device_info.Inbound.InterruptMask);
	} else if (!strcmp(dev_attr->attr.name, "in_read_index")) {
		return sprintf(buf, "%d\n", device_info.Inbound.ReadIndex);
	} else if (!strcmp(dev_attr->attr.name, "in_write_index")) {
		return sprintf(buf, "%d\n", device_info.Inbound.WriteIndex);
	} else if (!strcmp(dev_attr->attr.name, "in_read_bytes_avail")) {
		return sprintf(buf, "%d\n",
			       device_info.Inbound.BytesAvailToRead);
	} else if (!strcmp(dev_attr->attr.name, "in_write_bytes_avail")) {
		return sprintf(buf, "%d\n",
			       device_info.Inbound.BytesAvailToWrite);
	} else if (!strcmp(dev_attr->attr.name, "monitor_id")) {
		return sprintf(buf, "%d\n", device_info.MonitorId);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_pending")) {
		return sprintf(buf, "%d\n", device_info.ServerMonitorPending);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_latency")) {
		return sprintf(buf, "%d\n", device_info.ServerMonitorLatency);
	} else if (!strcmp(dev_attr->attr.name, "server_monitor_conn_id")) {
		return sprintf(buf, "%d\n",
			       device_info.ServerMonitorConnectionId);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_pending")) {
		return sprintf(buf, "%d\n", device_info.ClientMonitorPending);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_latency")) {
		return sprintf(buf, "%d\n", device_info.ClientMonitorLatency);
	} else if (!strcmp(dev_attr->attr.name, "client_monitor_conn_id")) {
		return sprintf(buf, "%d\n",
			       device_info.ClientMonitorConnectionId);
	} else {
		return 0;
	}
}

/**
 * vmbus_bus_init -Main vmbus driver initialization routine.
 *
 * Here, we
 * 	- initialize the vmbus driver context
 * 	- setup various driver entry points
 * 	- invoke the vmbus hv main init routine
 * 	- get the irq resource
 * 	- invoke the vmbus to add the vmbus root device
 * 	- setup the vmbus root device
 * 	- retrieve the channel offers
 */
static int vmbus_bus_init(int (*drv_init)(struct hv_driver *drv))
{
	struct vmbus_driver_context *vmbus_drv_ctx = &g_vmbus_drv;
	struct vmbus_driver *vmbus_drv_obj = &g_vmbus_drv.drv_obj;
	struct device_context *dev_ctx = &g_vmbus_drv.device_ctx;
	int ret;
	unsigned int vector;

	DPRINT_ENTER(VMBUS_DRV);

	/*
	 * Set this up to allow lower layer to callback to add/remove child
	 * devices on the bus
	 */
	vmbus_drv_obj->OnChildDeviceCreate = vmbus_child_device_create;
	vmbus_drv_obj->OnChildDeviceDestroy = vmbus_child_device_destroy;
	vmbus_drv_obj->OnChildDeviceAdd = vmbus_child_device_register;
	vmbus_drv_obj->OnChildDeviceRemove = vmbus_child_device_unregister;

	/* Call to bus driver to initialize */
	ret = drv_init(&vmbus_drv_obj->Base);
	if (ret != 0) {
		DPRINT_ERR(VMBUS_DRV, "Unable to initialize vmbus (%d)", ret);
		goto cleanup;
	}

	/* Sanity checks */
	if (!vmbus_drv_obj->Base.OnDeviceAdd) {
		DPRINT_ERR(VMBUS_DRV, "OnDeviceAdd() routine not set");
		ret = -1;
		goto cleanup;
	}

	vmbus_drv_ctx->bus.name = vmbus_drv_obj->Base.name;

	/* Initialize the bus context */
	tasklet_init(&vmbus_drv_ctx->msg_dpc, vmbus_msg_dpc,
		     (unsigned long)vmbus_drv_obj);
	tasklet_init(&vmbus_drv_ctx->event_dpc, vmbus_event_dpc,
		     (unsigned long)vmbus_drv_obj);

	/* Now, register the bus driver with LDM */
	ret = bus_register(&vmbus_drv_ctx->bus);
	if (ret) {
		ret = -1;
		goto cleanup;
	}

	/* Get the interrupt resource */
	ret = request_irq(vmbus_irq, vmbus_isr, IRQF_SAMPLE_RANDOM,
			  vmbus_drv_obj->Base.name, NULL);

	if (ret != 0) {
		DPRINT_ERR(VMBUS_DRV, "ERROR - Unable to request IRQ %d",
			   vmbus_irq);

		bus_unregister(&vmbus_drv_ctx->bus);

		ret = -1;
		goto cleanup;
	}
	vector = VMBUS_IRQ_VECTOR;

	DPRINT_INFO(VMBUS_DRV, "irq 0x%x vector 0x%x", vmbus_irq, vector);

	/* Call to bus driver to add the root device */
	memset(dev_ctx, 0, sizeof(struct device_context));

	ret = vmbus_drv_obj->Base.OnDeviceAdd(&dev_ctx->device_obj, &vector);
	if (ret != 0) {
		DPRINT_ERR(VMBUS_DRV,
			   "ERROR - Unable to add vmbus root device");

		free_irq(vmbus_irq, NULL);

		bus_unregister(&vmbus_drv_ctx->bus);

		ret = -1;
		goto cleanup;
	}
	/* strcpy(dev_ctx->device.bus_id, dev_ctx->device_obj.name); */
	dev_set_name(&dev_ctx->device, "vmbus_0_0");
	memcpy(&dev_ctx->class_id, &dev_ctx->device_obj.deviceType,
		sizeof(struct hv_guid));
	memcpy(&dev_ctx->device_id, &dev_ctx->device_obj.deviceInstance,
		sizeof(struct hv_guid));

	/* No need to bind a driver to the root device. */
	dev_ctx->device.parent = NULL;
	/* NULL; vmbus_remove() does not get invoked */
	dev_ctx->device.bus = &vmbus_drv_ctx->bus;

	/* Setup the device dispatch table */
	dev_ctx->device.release = vmbus_bus_release;

	/* Setup the bus as root device */
	ret = device_register(&dev_ctx->device);
	if (ret) {
		DPRINT_ERR(VMBUS_DRV,
			   "ERROR - Unable to register vmbus root device");

		free_irq(vmbus_irq, NULL);
		bus_unregister(&vmbus_drv_ctx->bus);

		ret = -1;
		goto cleanup;
	}


	vmbus_drv_obj->GetChannelOffers();

cleanup:
	DPRINT_EXIT(VMBUS_DRV);

	return ret;
}

/**
 * vmbus_bus_exit - Terminate the vmbus driver.
 *
 * This routine is opposite of vmbus_bus_init()
 */
static void vmbus_bus_exit(void)
{
	struct vmbus_driver *vmbus_drv_obj = &g_vmbus_drv.drv_obj;
	struct vmbus_driver_context *vmbus_drv_ctx = &g_vmbus_drv;

	struct device_context *dev_ctx = &g_vmbus_drv.device_ctx;

	DPRINT_ENTER(VMBUS_DRV);

	/* Remove the root device */
	if (vmbus_drv_obj->Base.OnDeviceRemove)
		vmbus_drv_obj->Base.OnDeviceRemove(&dev_ctx->device_obj);

	if (vmbus_drv_obj->Base.OnCleanup)
		vmbus_drv_obj->Base.OnCleanup(&vmbus_drv_obj->Base);

	/* Unregister the root bus device */
	device_unregister(&dev_ctx->device);

	bus_unregister(&vmbus_drv_ctx->bus);

	free_irq(vmbus_irq, NULL);

	tasklet_kill(&vmbus_drv_ctx->msg_dpc);
	tasklet_kill(&vmbus_drv_ctx->event_dpc);

	DPRINT_EXIT(VMBUS_DRV);

	return;
}

/**
 * vmbus_child_driver_register - Register a vmbus's child driver
 */
int vmbus_child_driver_register(struct driver_context *driver_ctx)
{
	struct vmbus_driver *vmbus_drv_obj = &g_vmbus_drv.drv_obj;
	int ret;

	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_INFO(VMBUS_DRV, "child driver (%p) registering - name %s",
		    driver_ctx, driver_ctx->driver.name);

	/* The child driver on this vmbus */
	driver_ctx->driver.bus = &g_vmbus_drv.bus;

	ret = driver_register(&driver_ctx->driver);

	vmbus_drv_obj->GetChannelOffers();

	DPRINT_EXIT(VMBUS_DRV);

	return ret;
}
EXPORT_SYMBOL(vmbus_child_driver_register);

/**
 * vmbus_child_driver_unregister Unregister a vmbus's child driver
 */
void vmbus_child_driver_unregister(struct driver_context *driver_ctx)
{
	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_INFO(VMBUS_DRV, "child driver (%p) unregistering - name %s",
		    driver_ctx, driver_ctx->driver.name);

	driver_unregister(&driver_ctx->driver);

	driver_ctx->driver.bus = NULL;

	DPRINT_EXIT(VMBUS_DRV);
}
EXPORT_SYMBOL(vmbus_child_driver_unregister);

/**
 * vmbus_get_interface - Get the vmbus channel interface.
 *
 * This is invoked by child/client driver that sits above vmbus
 */
void vmbus_get_interface(struct vmbus_channel_interface *interface)
{
	struct vmbus_driver *vmbus_drv_obj = &g_vmbus_drv.drv_obj;

	vmbus_drv_obj->GetChannelInterface(interface);
}
EXPORT_SYMBOL(vmbus_get_interface);

/**
 * vmbus_child_device_get_info - Get the vmbus child device info.
 *
 * This is invoked to display various device attributes in sysfs.
 */
static void vmbus_child_device_get_info(struct hv_device *device_obj,
					struct hv_device_info *device_info)
{
	struct vmbus_driver *vmbus_drv_obj = &g_vmbus_drv.drv_obj;

	vmbus_drv_obj->GetChannelInfo(device_obj, device_info);
}

/**
 * vmbus_child_device_create - Creates and registers a new child device on the vmbus.
 */
static struct hv_device *vmbus_child_device_create(struct hv_guid *type,
						   struct hv_guid *instance,
						   void *context)
{
	struct device_context *child_device_ctx;
	struct hv_device *child_device_obj;

	DPRINT_ENTER(VMBUS_DRV);

	/* Allocate the new child device */
	child_device_ctx = kzalloc(sizeof(struct device_context), GFP_KERNEL);
	if (!child_device_ctx) {
		DPRINT_ERR(VMBUS_DRV,
			"unable to allocate device_context for child device");
		DPRINT_EXIT(VMBUS_DRV);

		return NULL;
	}

	DPRINT_DBG(VMBUS_DRV, "child device (%p) allocated - "
		"type {%02x%02x%02x%02x-%02x%02x-%02x%02x-"
		"%02x%02x%02x%02x%02x%02x%02x%02x},"
		"id {%02x%02x%02x%02x-%02x%02x-%02x%02x-"
		"%02x%02x%02x%02x%02x%02x%02x%02x}",
		&child_device_ctx->device,
		type->data[3], type->data[2], type->data[1], type->data[0],
		type->data[5], type->data[4], type->data[7], type->data[6],
		type->data[8], type->data[9], type->data[10], type->data[11],
		type->data[12], type->data[13], type->data[14], type->data[15],
		instance->data[3], instance->data[2],
		instance->data[1], instance->data[0],
		instance->data[5], instance->data[4],
		instance->data[7], instance->data[6],
		instance->data[8], instance->data[9],
		instance->data[10], instance->data[11],
		instance->data[12], instance->data[13],
		instance->data[14], instance->data[15]);

	child_device_obj = &child_device_ctx->device_obj;
	child_device_obj->context = context;
	memcpy(&child_device_obj->deviceType, type, sizeof(struct hv_guid));
	memcpy(&child_device_obj->deviceInstance, instance,
	       sizeof(struct hv_guid));

	memcpy(&child_device_ctx->class_id, type, sizeof(struct hv_guid));
	memcpy(&child_device_ctx->device_id, instance, sizeof(struct hv_guid));

	DPRINT_EXIT(VMBUS_DRV);

	return child_device_obj;
}

/**
 * vmbus_child_device_register - Register the child device on the specified bus
 */
static int vmbus_child_device_register(struct hv_device *root_device_obj,
				       struct hv_device *child_device_obj)
{
	int ret = 0;
	struct device_context *root_device_ctx =
				to_device_context(root_device_obj);
	struct device_context *child_device_ctx =
				to_device_context(child_device_obj);
	static atomic_t device_num = ATOMIC_INIT(0);

	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_DBG(VMBUS_DRV, "child device (%p) registering",
		   child_device_ctx);

	/* Set the device name. Otherwise, device_register() will fail. */
	dev_set_name(&child_device_ctx->device, "vmbus_0_%d",
		     atomic_inc_return(&device_num));

	/* The new device belongs to this bus */
	child_device_ctx->device.bus = &g_vmbus_drv.bus; /* device->dev.bus; */
	child_device_ctx->device.parent = &root_device_ctx->device;
	child_device_ctx->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_ctx->device);

	/* vmbus_probe() error does not get propergate to device_register(). */
	ret = child_device_ctx->probe_error;

	if (ret)
		DPRINT_ERR(VMBUS_DRV, "unable to register child device (%p)",
			   &child_device_ctx->device);
	else
		DPRINT_INFO(VMBUS_DRV, "child device (%p) registered",
			    &child_device_ctx->device);

	DPRINT_EXIT(VMBUS_DRV);

	return ret;
}

/**
 * vmbus_child_device_unregister - Remove the specified child device from the vmbus.
 */
static void vmbus_child_device_unregister(struct hv_device *device_obj)
{
	struct device_context *device_ctx = to_device_context(device_obj);

	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_INFO(VMBUS_DRV, "unregistering child device (%p)",
		    &device_ctx->device);

	/*
	 * Kick off the process of unregistering the device.
	 * This will call vmbus_remove() and eventually vmbus_device_release()
	 */
	device_unregister(&device_ctx->device);

	DPRINT_INFO(VMBUS_DRV, "child device (%p) unregistered",
		    &device_ctx->device);

	DPRINT_EXIT(VMBUS_DRV);
}

/**
 * vmbus_child_device_destroy - Destroy the specified child device on the vmbus.
 */
static void vmbus_child_device_destroy(struct hv_device *device_obj)
{
	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_EXIT(VMBUS_DRV);
}

/**
 * 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
 */
static int vmbus_uevent(struct device *device, struct kobj_uevent_env *env)
{
	struct device_context *device_ctx = device_to_device_context(device);
	int ret;

	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_INFO(VMBUS_DRV, "generating uevent - VMBUS_DEVICE_CLASS_GUID={"
		    "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
		    "%02x%02x%02x%02x%02x%02x%02x%02x}",
		    device_ctx->class_id.data[3], device_ctx->class_id.data[2],
		    device_ctx->class_id.data[1], device_ctx->class_id.data[0],
		    device_ctx->class_id.data[5], device_ctx->class_id.data[4],
		    device_ctx->class_id.data[7], device_ctx->class_id.data[6],
		    device_ctx->class_id.data[8], device_ctx->class_id.data[9],
		    device_ctx->class_id.data[10],
		    device_ctx->class_id.data[11],
		    device_ctx->class_id.data[12],
		    device_ctx->class_id.data[13],
		    device_ctx->class_id.data[14],
		    device_ctx->class_id.data[15]);

	ret = add_uevent_var(env, "VMBUS_DEVICE_CLASS_GUID={"
			     "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
			     "%02x%02x%02x%02x%02x%02x%02x%02x}",
			     device_ctx->class_id.data[3],
			     device_ctx->class_id.data[2],
			     device_ctx->class_id.data[1],
			     device_ctx->class_id.data[0],
			     device_ctx->class_id.data[5],
			     device_ctx->class_id.data[4],
			     device_ctx->class_id.data[7],
			     device_ctx->class_id.data[6],
			     device_ctx->class_id.data[8],
			     device_ctx->class_id.data[9],
			     device_ctx->class_id.data[10],
			     device_ctx->class_id.data[11],
			     device_ctx->class_id.data[12],
			     device_ctx->class_id.data[13],
			     device_ctx->class_id.data[14],
			     device_ctx->class_id.data[15]);

	if (ret)
		return ret;

	ret = add_uevent_var(env, "VMBUS_DEVICE_DEVICE_GUID={"
			     "%02x%02x%02x%02x-%02x%02x-%02x%02x-"
			     "%02x%02x%02x%02x%02x%02x%02x%02x}",
			     device_ctx->device_id.data[3],
			     device_ctx->device_id.data[2],
			     device_ctx->device_id.data[1],
			     device_ctx->device_id.data[0],
			     device_ctx->device_id.data[5],
			     device_ctx->device_id.data[4],
			     device_ctx->device_id.data[7],
			     device_ctx->device_id.data[6],
			     device_ctx->device_id.data[8],
			     device_ctx->device_id.data[9],
			     device_ctx->device_id.data[10],
			     device_ctx->device_id.data[11],
			     device_ctx->device_id.data[12],
			     device_ctx->device_id.data[13],
			     device_ctx->device_id.data[14],
			     device_ctx->device_id.data[15]);
	if (ret)
		return ret;

	DPRINT_EXIT(VMBUS_DRV);

	return 0;
}

/**
 * vmbus_match - Attempt to match the specified device to the specified driver
 */
static int vmbus_match(struct device *device, struct device_driver *driver)
{
	int match = 0;
	struct driver_context *driver_ctx = driver_to_driver_context(driver);
	struct device_context *device_ctx = device_to_device_context(device);

	DPRINT_ENTER(VMBUS_DRV);

	/* We found our driver ? */
	if (memcmp(&device_ctx->class_id, &driver_ctx->class_id,
		   sizeof(struct hv_guid)) == 0) {
		/*
		 * !! NOTE: The driver_ctx is not a vmbus_drv_ctx. We typecast
		 * it here to access the struct hv_driver field
		 */
		struct vmbus_driver_context *vmbus_drv_ctx =
			(struct vmbus_driver_context *)driver_ctx;

		device_ctx->device_obj.Driver = &vmbus_drv_ctx->drv_obj.Base;
		DPRINT_INFO(VMBUS_DRV,
			    "device object (%p) set to driver object (%p)",
			    &device_ctx->device_obj,
			    device_ctx->device_obj.Driver);

		match = 1;
	}

	DPRINT_EXIT(VMBUS_DRV);

	return match;
}

/**
 * vmbus_probe_failed_cb - Callback when a driver probe failed in vmbus_probe()
 *
 * We need a callback because we cannot invoked device_unregister() inside
 * vmbus_probe() since vmbus_probe() may be invoked inside device_register()
 * i.e. we cannot call device_unregister() inside device_register()
 */
static void vmbus_probe_failed_cb(struct work_struct *context)
{
	struct device_context *device_ctx = (struct device_context *)context;

	DPRINT_ENTER(VMBUS_DRV);

	/*
	 * Kick off the process of unregistering the device.
	 * This will call vmbus_remove() and eventually vmbus_device_release()
	 */
	device_unregister(&device_ctx->device);

	/* put_device(&device_ctx->device); */
	DPRINT_EXIT(VMBUS_DRV);
}

/**
 * vmbus_probe - Add the new vmbus's child device
 */
static int vmbus_probe(struct device *child_device)
{
	int ret = 0;
	struct driver_context *driver_ctx =
			driver_to_driver_context(child_device->driver);
	struct device_context *device_ctx =
			device_to_device_context(child_device);

	DPRINT_ENTER(VMBUS_DRV);

	/* Let the specific open-source driver handles the probe if it can */
	if (driver_ctx->probe) {
		ret = device_ctx->probe_error = driver_ctx->probe(child_device);
		if (ret != 0) {
			DPRINT_ERR(VMBUS_DRV, "probe() failed for device %s "
				   "(%p) on driver %s (%d)...",
				   dev_name(child_device), child_device,
				   child_device->driver->name, ret);

			INIT_WORK(&device_ctx->probe_failed_work_item,
				  vmbus_probe_failed_cb);
			schedule_work(&device_ctx->probe_failed_work_item);
		}
	} else {
		DPRINT_ERR(VMBUS_DRV, "probe() method not set for driver - %s",
			   child_device->driver->name);
		ret = -1;
	}

	DPRINT_EXIT(VMBUS_DRV);
	return ret;
}

/**
 * vmbus_remove - Remove a vmbus device
 */
static int vmbus_remove(struct device *child_device)
{
	int ret;
	struct driver_context *driver_ctx;

	DPRINT_ENTER(VMBUS_DRV);

	/* Special case root bus device */
	if (child_device->parent == NULL) {
		/*
		 * No-op since it is statically defined and handle in
		 * vmbus_bus_exit()
		 */
		DPRINT_EXIT(VMBUS_DRV);
		return 0;
	}

	if (child_device->driver) {
		driver_ctx = driver_to_driver_context(child_device->driver);

		/*
		 * Let the specific open-source driver handles the removal if
		 * it can
		 */
		if (driver_ctx->remove) {
			ret = driver_ctx->remove(child_device);
		} else {
			DPRINT_ERR(VMBUS_DRV,
				   "remove() method not set for driver - %s",
				   child_device->driver->name);
			ret = -1;
		}
	}

	DPRINT_EXIT(VMBUS_DRV);

	return 0;
}

/**
 * vmbus_shutdown - Shutdown a vmbus device
 */
static void vmbus_shutdown(struct device *child_device)
{
	struct driver_context *driver_ctx;

	DPRINT_ENTER(VMBUS_DRV);

	/* Special case root bus device */
	if (child_device->parent == NULL) {
		/*
		 * No-op since it is statically defined and handle in
		 * vmbus_bus_exit()
		 */
		DPRINT_EXIT(VMBUS_DRV);
		return;
	}

	/* The device may not be attached yet */
	if (!child_device->driver) {
		DPRINT_EXIT(VMBUS_DRV);
		return;
	}

	driver_ctx = driver_to_driver_context(child_device->driver);

	/* Let the specific open-source driver handles the removal if it can */
	if (driver_ctx->shutdown)
		driver_ctx->shutdown(child_device);

	DPRINT_EXIT(VMBUS_DRV);

	return;
}

/**
 * vmbus_bus_release - Final callback release of the vmbus root device
 */
static void vmbus_bus_release(struct device *device)
{
	DPRINT_ENTER(VMBUS_DRV);
	/* FIXME */
	/* Empty release functions are a bug, or a major sign
	 * of a problem design, this MUST BE FIXED! */
	dev_err(device, "%s needs to be fixed!\n", __func__);
	WARN_ON(1);
	DPRINT_EXIT(VMBUS_DRV);
}

/**
 * vmbus_device_release - Final callback release of the vmbus child device
 */
static void vmbus_device_release(struct device *device)
{
	struct device_context *device_ctx = device_to_device_context(device);

	DPRINT_ENTER(VMBUS_DRV);

	/* vmbus_child_device_destroy(&device_ctx->device_obj); */
	kfree(device_ctx);

	/* !!DO NOT REFERENCE device_ctx anymore at this point!! */
	DPRINT_EXIT(VMBUS_DRV);

	return;
}

/**
 * vmbus_msg_dpc - Tasklet routine to handle hypervisor messages
 */
static void vmbus_msg_dpc(unsigned long data)
{
	struct vmbus_driver *vmbus_drv_obj = (struct vmbus_driver *)data;

	DPRINT_ENTER(VMBUS_DRV);

	ASSERT(vmbus_drv_obj->OnMsgDpc != NULL);

	/* Call to bus driver to handle interrupt */
	vmbus_drv_obj->OnMsgDpc(&vmbus_drv_obj->Base);

	DPRINT_EXIT(VMBUS_DRV);
}

/**
 * vmbus_msg_dpc - Tasklet routine to handle hypervisor events
 */
static void vmbus_event_dpc(unsigned long data)
{
	struct vmbus_driver *vmbus_drv_obj = (struct vmbus_driver *)data;

	DPRINT_ENTER(VMBUS_DRV);

	ASSERT(vmbus_drv_obj->OnEventDpc != NULL);

	/* Call to bus driver to handle interrupt */
	vmbus_drv_obj->OnEventDpc(&vmbus_drv_obj->Base);

	DPRINT_EXIT(VMBUS_DRV);
}

static irqreturn_t vmbus_isr(int irq, void *dev_id)
{
	struct vmbus_driver *vmbus_driver_obj = &g_vmbus_drv.drv_obj;
	int ret;

	DPRINT_ENTER(VMBUS_DRV);

	ASSERT(vmbus_driver_obj->OnIsr != NULL);

	/* Call to bus driver to handle interrupt */
	ret = vmbus_driver_obj->OnIsr(&vmbus_driver_obj->Base);

	/* Schedules a dpc if necessary */
	if (ret > 0) {
		if (test_bit(0, (unsigned long *)&ret))
			tasklet_schedule(&g_vmbus_drv.msg_dpc);

		if (test_bit(1, (unsigned long *)&ret))
			tasklet_schedule(&g_vmbus_drv.event_dpc);

		DPRINT_EXIT(VMBUS_DRV);
		return IRQ_HANDLED;
	} else {
		DPRINT_EXIT(VMBUS_DRV);
		return IRQ_NONE;
	}
}

static struct dmi_system_id __initdata microsoft_hv_dmi_table[] = {
	{
		.ident = "Hyper-V",
		.matches = {
			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft Corporation"),
			DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
			DMI_MATCH(DMI_BOARD_NAME, "Virtual Machine"),
		},
	},
	{ },
};
MODULE_DEVICE_TABLE(dmi, microsoft_hv_dmi_table);

static int __init vmbus_init(void)
{
	int ret = 0;

	DPRINT_ENTER(VMBUS_DRV);

	DPRINT_INFO(VMBUS_DRV,
		"Vmbus initializing.... current log level 0x%x (%x,%x)",
		vmbus_loglevel, HIWORD(vmbus_loglevel), LOWORD(vmbus_loglevel));
	/* Todo: it is used for loglevel, to be ported to new kernel. */

	if (!dmi_check_system(microsoft_hv_dmi_table))
		return -ENODEV;

	ret = vmbus_bus_init(VmbusInitialize);

	DPRINT_EXIT(VMBUS_DRV);
	return ret;
}

static void __exit vmbus_exit(void)
{
	DPRINT_ENTER(VMBUS_DRV);

	vmbus_bus_exit();
	/* Todo: it is used for loglevel, to be ported to new kernel. */
	DPRINT_EXIT(VMBUS_DRV);
	return;
}

/*
 * We use a PCI table to determine if we should autoload this driver  This is
 * needed by distro tools to determine if the hyperv drivers should be
 * installed and/or configured.  We don't do anything else with the table, but
 * it needs to be present.
 */
const static struct pci_device_id microsoft_hv_pci_table[] = {
	{ PCI_DEVICE(0x1414, 0x5353) },	/* VGA compatible controller */
	{ 0 }
};
MODULE_DEVICE_TABLE(pci, microsoft_hv_pci_table);

MODULE_LICENSE("GPL");
module_param(vmbus_irq, int, S_IRUGO);
module_param(vmbus_loglevel, int, S_IRUGO);

module_init(vmbus_init);
module_exit(vmbus_exit);