Staging: hv: Make event_dpc a stand alone variable

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / staging / hv / vmbus_drv.c

/*
 * 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>
 *
 * 3/9/2011: K. Y. Srinivasan   - Significant restructuring and cleanup
 */
#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/pci.h>
#include <linux/dmi.h>
#include <linux/slab.h>
#include <linux/completion.h>
#include "version_info.h"
#include "hv_api.h"
#include "logging.h"
#include "vmbus.h"
#include "channel.h"
#include "vmbus_private.h"


static struct pci_dev *hv_pci_dev;

static struct tasklet_struct msg_dpc;
static struct tasklet_struct event_dpc;

/* Main vmbus driver data structure */
struct hv_bus {
        struct bus_type bus;
};

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 pci_probe_error;
static struct completion probe_event;

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(struct hv_guid));
        memcpy(&info->chn_instance, &debug_info.interface_instance,
               sizeof(struct hv_guid));

        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;
}

/*
 * 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 *device_ctx = device_to_hv_device(dev);
        struct hv_device_info device_info;

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

        get_channel_info(device_ctx, &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.chn_type.data[3],
                               device_info.chn_type.data[2],
                               device_info.chn_type.data[1],
                               device_info.chn_type.data[0],
                               device_info.chn_type.data[5],
                               device_info.chn_type.data[4],
                               device_info.chn_type.data[7],
                               device_info.chn_type.data[6],
                               device_info.chn_type.data[8],
                               device_info.chn_type.data[9],
                               device_info.chn_type.data[10],
                               device_info.chn_type.data[11],
                               device_info.chn_type.data[12],
                               device_info.chn_type.data[13],
                               device_info.chn_type.data[14],
                               device_info.chn_type.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.chn_instance.data[3],
                               device_info.chn_instance.data[2],
                               device_info.chn_instance.data[1],
                               device_info.chn_instance.data[0],
                               device_info.chn_instance.data[5],
                               device_info.chn_instance.data[4],
                               device_info.chn_instance.data[7],
                               device_info.chn_instance.data[6],
                               device_info.chn_instance.data[8],
                               device_info.chn_instance.data[9],
                               device_info.chn_instance.data[10],
                               device_info.chn_instance.data[11],
                               device_info.chn_instance.data[12],
                               device_info.chn_instance.data[13],
                               device_info.chn_instance.data[14],
                               device_info.chn_instance.data[15]);
        } else if (!strcmp(dev_attr->attr.name, "state")) {
                return sprintf(buf, "%d\n", device_info.chn_state);
        } else if (!strcmp(dev_attr->attr.name, "id")) {
                return sprintf(buf, "%d\n", device_info.chn_id);
        } else if (!strcmp(dev_attr->attr.name, "out_intr_mask")) {
                return sprintf(buf, "%d\n", device_info.outbound.int_mask);
        } else if (!strcmp(dev_attr->attr.name, "out_read_index")) {
                return sprintf(buf, "%d\n", device_info.outbound.read_idx);
        } else if (!strcmp(dev_attr->attr.name, "out_write_index")) {
                return sprintf(buf, "%d\n", device_info.outbound.write_idx);
        } else if (!strcmp(dev_attr->attr.name, "out_read_bytes_avail")) {
                return sprintf(buf, "%d\n",
                               device_info.outbound.bytes_avail_toread);
        } else if (!strcmp(dev_attr->attr.name, "out_write_bytes_avail")) {
                return sprintf(buf, "%d\n",
                               device_info.outbound.bytes_avail_towrite);
        } else if (!strcmp(dev_attr->attr.name, "in_intr_mask")) {
                return sprintf(buf, "%d\n", device_info.inbound.int_mask);
        } else if (!strcmp(dev_attr->attr.name, "in_read_index")) {
                return sprintf(buf, "%d\n", device_info.inbound.read_idx);
        } else if (!strcmp(dev_attr->attr.name, "in_write_index")) {
                return sprintf(buf, "%d\n", device_info.inbound.write_idx);
        } else if (!strcmp(dev_attr->attr.name, "in_read_bytes_avail")) {
                return sprintf(buf, "%d\n",
                               device_info.inbound.bytes_avail_toread);
        } else if (!strcmp(dev_attr->attr.name, "in_write_bytes_avail")) {
                return sprintf(buf, "%d\n",
                               device_info.inbound.bytes_avail_towrite);
        } else if (!strcmp(dev_attr->attr.name, "monitor_id")) {
                return sprintf(buf, "%d\n", device_info.monitor_id);
        } else if (!strcmp(dev_attr->attr.name, "server_monitor_pending")) {
                return sprintf(buf, "%d\n", device_info.server_monitor_pending);
        } else if (!strcmp(dev_attr->attr.name, "server_monitor_latency")) {
                return sprintf(buf, "%d\n", device_info.server_monitor_latency);
        } else if (!strcmp(dev_attr->attr.name, "server_monitor_conn_id")) {
                return sprintf(buf, "%d\n",
                               device_info.server_monitor_conn_id);
        } else if (!strcmp(dev_attr->attr.name, "client_monitor_pending")) {
                return sprintf(buf, "%d\n", device_info.client_monitor_pending);
        } else if (!strcmp(dev_attr->attr.name, "client_monitor_latency")) {
                return sprintf(buf, "%d\n", device_info.client_monitor_latency);
        } else if (!strcmp(dev_attr->attr.name, "client_monitor_conn_id")) {
                return sprintf(buf, "%d\n",
                               device_info.client_monitor_conn_id);
        } else {
                return 0;
        }
}

/* 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
};


/*
 * 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 hv_device *dev = device_to_hv_device(device);
        int ret;

        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}",
                             dev->dev_type.data[3],
                             dev->dev_type.data[2],
                             dev->dev_type.data[1],
                             dev->dev_type.data[0],
                             dev->dev_type.data[5],
                             dev->dev_type.data[4],
                             dev->dev_type.data[7],
                             dev->dev_type.data[6],
                             dev->dev_type.data[8],
                             dev->dev_type.data[9],
                             dev->dev_type.data[10],
                             dev->dev_type.data[11],
                             dev->dev_type.data[12],
                             dev->dev_type.data[13],
                             dev->dev_type.data[14],
                             dev->dev_type.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}",
                             dev->dev_instance.data[3],
                             dev->dev_instance.data[2],
                             dev->dev_instance.data[1],
                             dev->dev_instance.data[0],
                             dev->dev_instance.data[5],
                             dev->dev_instance.data[4],
                             dev->dev_instance.data[7],
                             dev->dev_instance.data[6],
                             dev->dev_instance.data[8],
                             dev->dev_instance.data[9],
                             dev->dev_instance.data[10],
                             dev->dev_instance.data[11],
                             dev->dev_instance.data[12],
                             dev->dev_instance.data[13],
                             dev->dev_instance.data[14],
                             dev->dev_instance.data[15]);
        if (ret)
                return ret;

        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 hv_driver *drv = drv_to_hv_drv(driver);
        struct hv_device *device_ctx = device_to_hv_device(device);

        /* We found our driver ? */
        if (memcmp(&device_ctx->dev_type, &drv->dev_type,
                   sizeof(struct hv_guid)) == 0)
                match = 1;

        return match;
}

/*
 * 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);

        /* Let the specific open-source driver handles the probe if it can */
        if (drv->driver.probe) {
                ret = drv->driver.probe(child_device);
                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 = -1;
        }
        return ret;
}

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


        if (child_device->driver) {
                drv = drv_to_hv_drv(child_device->driver);

                /*
                 * Let the specific open-source driver handles the removal if
                 * it can
                 */
                if (drv->driver.remove) {
                        ret = drv->driver.remove(child_device);
                } else {
                        pr_err("remove not set for driver %s\n",
                                dev_name(child_device));
                        ret = -1;
                }
        }

        return 0;
}


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


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

        drv = drv_to_hv_drv(child_device->driver);

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

        return;
}


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

        kfree(device_ctx);

}

/* The one and only one */
static struct hv_bus  hv_bus = {
        .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,
};

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);
}

/*
 * vmbus_on_msg_dpc - DPC routine to handle messages from the hypervisior
 */
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
                 */
                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);
                }
        }
}

/*
 * vmbus_on_isr - ISR routine
 */
static int vmbus_on_isr(void)
{
        int ret = 0;
        int cpu = smp_processor_id();
        void *page_addr;
        struct hv_message *msg;
        union hv_synic_event_flags *event;

        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 process */
        if (msg->header.message_type != HVMSG_NONE)
                ret |= 0x1;

        /* TODO: Check if there are events to be process */
        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]))
                ret |= 0x2;

        return ret;
}


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

        ret = vmbus_on_isr();

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

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

                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(struct pci_dev *pdev)
{
        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);
                goto cleanup;
        }

        hv_bus.bus.name = driver_name;

        /* Initialize the bus context */
        tasklet_init(&msg_dpc, vmbus_on_msg_dpc, 0);
        tasklet_init(&event_dpc, vmbus_on_event, 0);

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

        /* Get the interrupt resource */
        ret = request_irq(pdev->irq, vmbus_isr,
                          IRQF_SHARED | IRQF_SAMPLE_RANDOM,
                          driver_name, pdev);

        if (ret != 0) {
                pr_err("Unable to request IRQ %d\n",
                           pdev->irq);

                bus_unregister(&hv_bus.bus);

                ret = -1;
                goto cleanup;
        }

        vector = IRQ0_VECTOR + pdev->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) {
                free_irq(pdev->irq, pdev);
                bus_unregister(&hv_bus.bus);
                goto cleanup;
        }


        vmbus_request_offers();
        wait_for_completion(&hv_channel_ready);

cleanup:
        return ret;
}

/**
 * vmbus_child_driver_register() - Register a vmbus's child driver
 * @drv:        Pointer to driver structure you want to register
 *
 *
 * 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.
 *
 * Mainly used by Hyper-V drivers.
 */
int vmbus_child_driver_register(struct device_driver *drv)
{
        int ret;

        pr_info("child driver registering - name %s\n", drv->name);

        /* The child driver on this vmbus */
        drv->bus = &hv_bus.bus;

        ret = driver_register(drv);

        vmbus_request_offers();

        return ret;
}
EXPORT_SYMBOL(vmbus_child_driver_register);

/**
 * vmbus_child_driver_unregister() - Unregister a vmbus's child driver
 * @drv:        Pointer to driver structure you want to un-register
 *
 *
 * Un-register the given driver with Linux through the 'driver_unregister()'
 * call. And ungegisters the driver from the Hyper-V vmbus handler.
 *
 * Mainly used by Hyper-V drivers.
 */
void vmbus_child_driver_unregister(struct device_driver *drv)
{
        pr_info("child driver unregistering - name %s\n", drv->name);

        driver_unregister(drv);

        drv->bus = NULL;
}
EXPORT_SYMBOL(vmbus_child_driver_unregister);

/*
 * vmbus_child_device_create - Creates and registers a new child device
 * on the vmbus.
 */
struct hv_device *vmbus_child_device_create(struct hv_guid *type,
                                            struct hv_guid *instance,
                                            struct vmbus_channel *channel)
{
        struct hv_device *child_device_obj;

        /* Allocate the new child device */
        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(struct hv_guid));
        memcpy(&child_device_obj->dev_instance, instance,
               sizeof(struct hv_guid));


        return child_device_obj;
}

/*
 * vmbus_child_device_register - Register the child device
 */
int vmbus_child_device_register(struct hv_device *child_device_obj)
{
        int ret = 0;

        static atomic_t device_num = ATOMIC_INIT(0);

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

        /* The new device belongs to this bus */
        child_device_obj->device.bus = &hv_bus.bus; /* device->dev.bus; */
        child_device_obj->device.parent = &hv_pci_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_child_device_unregister - Remove the specified child device
 * from the vmbus.
 */
void vmbus_child_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));
}


static int __devinit hv_pci_probe(struct pci_dev *pdev,
                                const struct pci_device_id *ent)
{
        hv_pci_dev = pdev;

        pci_probe_error = pci_enable_device(pdev);
        if (pci_probe_error)
                goto probe_cleanup;

        pci_probe_error = vmbus_bus_init(pdev);
        if (pci_probe_error)
                pci_disable_device(pdev);

probe_cleanup:
        complete(&probe_event);
        return pci_probe_error;
}

/*
 * 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.
 */
static const struct pci_device_id microsoft_hv_pci_table[] = {
        { PCI_DEVICE(0x1414, 0x5353) }, /* VGA compatible controller */
        { 0 }
};
MODULE_DEVICE_TABLE(pci, microsoft_hv_pci_table);

static struct pci_driver hv_bus_driver = {
        .name =           "hv_bus",
        .probe =          hv_pci_probe,
        .id_table =       microsoft_hv_pci_table,
};

static int __init hv_pci_init(void)
{
        int ret;
        init_completion(&probe_event);
        ret = pci_register_driver(&hv_bus_driver);
        if (ret)
                return ret;
        /*
         * All the vmbus initialization occurs within the
         * hv_pci_probe() function. Wait for hv_pci_probe()
         * to complete.
         */
        wait_for_completion(&probe_event);

        if (pci_probe_error)
                pci_unregister_driver(&hv_bus_driver);
        return pci_probe_error;
}


MODULE_LICENSE("GPL");
MODULE_VERSION(HV_DRV_VERSION);
module_param(vmbus_loglevel, int, S_IRUGO|S_IWUSR);

module_init(hv_pci_init);