slub: fix high order page allocation problem with __GFP_NOFAIL

[linux-2.6/btrfs-unstable.git] / drivers / 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>
 *   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 <linux/completion.h>
#include <linux/hyperv.h>
#include <linux/kernel_stat.h>
#include <asm/hyperv.h>
#include <asm/hypervisor.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"

static struct acpi_device  *hv_acpi_dev;

static struct tasklet_struct msg_dpc;
static struct completion probe_event;
static int irq;

static int vmbus_exists(void)
{
        if (hv_acpi_dev == NULL)
                return -ENODEV;

        return 0;
}

#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]);
}

static u8 channel_monitor_group(struct vmbus_channel *channel)
{
        return (u8)channel->offermsg.monitorid / 32;
}

static u8 channel_monitor_offset(struct vmbus_channel *channel)
{
        return (u8)channel->offermsg.monitorid % 32;
}

static u32 channel_pending(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        return monitor_page->trigger_group[monitor_group].pending;
}

static u32 channel_latency(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        u8 monitor_offset = channel_monitor_offset(channel);
        return monitor_page->latency[monitor_group][monitor_offset];
}

static u32 channel_conn_id(struct vmbus_channel *channel,
                           struct hv_monitor_page *monitor_page)
{
        u8 monitor_group = channel_monitor_group(channel);
        u8 monitor_offset = channel_monitor_offset(channel);
        return monitor_page->parameter[monitor_group][monitor_offset].connectionid.u.id;
}

static ssize_t id_show(struct device *dev, struct device_attribute *dev_attr,
                       char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->offermsg.child_relid);
}
static DEVICE_ATTR_RO(id);

static ssize_t state_show(struct device *dev, struct device_attribute *dev_attr,
                          char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->state);
}
static DEVICE_ATTR_RO(state);

static ssize_t monitor_id_show(struct device *dev,
                               struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n", hv_dev->channel->offermsg.monitorid);
}
static DEVICE_ATTR_RO(monitor_id);

static ssize_t class_id_show(struct device *dev,
                               struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "{%pUl}\n",
                       hv_dev->channel->offermsg.offer.if_type.b);
}
static DEVICE_ATTR_RO(class_id);

static ssize_t device_id_show(struct device *dev,
                              struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "{%pUl}\n",
                       hv_dev->channel->offermsg.offer.if_instance.b);
}
static DEVICE_ATTR_RO(device_id);

static ssize_t modalias_show(struct device *dev,
                             struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        char alias_name[VMBUS_ALIAS_LEN + 1];

        print_alias_name(hv_dev, alias_name);
        return sprintf(buf, "vmbus:%s\n", alias_name);
}
static DEVICE_ATTR_RO(modalias);

static ssize_t server_monitor_pending_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_pending(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(server_monitor_pending);

static ssize_t client_monitor_pending_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_pending(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_pending);

static ssize_t server_monitor_latency_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_latency(hv_dev->channel,
                                       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_latency);

static ssize_t client_monitor_latency_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_latency(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_latency);

static ssize_t server_monitor_conn_id_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_conn_id(hv_dev->channel,
                                       vmbus_connection.monitor_pages[0]));
}
static DEVICE_ATTR_RO(server_monitor_conn_id);

static ssize_t client_monitor_conn_id_show(struct device *dev,
                                           struct device_attribute *dev_attr,
                                           char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);

        if (!hv_dev->channel)
                return -ENODEV;
        return sprintf(buf, "%d\n",
                       channel_conn_id(hv_dev->channel,
                                       vmbus_connection.monitor_pages[1]));
}
static DEVICE_ATTR_RO(client_monitor_conn_id);

static ssize_t out_intr_mask_show(struct device *dev,
                                  struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(out_intr_mask);

static ssize_t out_read_index_show(struct device *dev,
                                   struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_read_index);
}
static DEVICE_ATTR_RO(out_read_index);

static ssize_t out_write_index_show(struct device *dev,
                                    struct device_attribute *dev_attr,
                                    char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.current_write_index);
}
static DEVICE_ATTR_RO(out_write_index);

static ssize_t out_read_bytes_avail_show(struct device *dev,
                                         struct device_attribute *dev_attr,
                                         char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(out_read_bytes_avail);

static ssize_t out_write_bytes_avail_show(struct device *dev,
                                          struct device_attribute *dev_attr,
                                          char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info outbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->outbound, &outbound);
        return sprintf(buf, "%d\n", outbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(out_write_bytes_avail);

static ssize_t in_intr_mask_show(struct device *dev,
                                 struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_interrupt_mask);
}
static DEVICE_ATTR_RO(in_intr_mask);

static ssize_t in_read_index_show(struct device *dev,
                                  struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_read_index);
}
static DEVICE_ATTR_RO(in_read_index);

static ssize_t in_write_index_show(struct device *dev,
                                   struct device_attribute *dev_attr, char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.current_write_index);
}
static DEVICE_ATTR_RO(in_write_index);

static ssize_t in_read_bytes_avail_show(struct device *dev,
                                        struct device_attribute *dev_attr,
                                        char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.bytes_avail_toread);
}
static DEVICE_ATTR_RO(in_read_bytes_avail);

static ssize_t in_write_bytes_avail_show(struct device *dev,
                                         struct device_attribute *dev_attr,
                                         char *buf)
{
        struct hv_device *hv_dev = device_to_hv_device(dev);
        struct hv_ring_buffer_debug_info inbound;

        if (!hv_dev->channel)
                return -ENODEV;
        hv_ringbuffer_get_debuginfo(&hv_dev->channel->inbound, &inbound);
        return sprintf(buf, "%d\n", inbound.bytes_avail_towrite);
}
static DEVICE_ATTR_RO(in_write_bytes_avail);

/* Set up per device attributes in /sys/bus/vmbus/devices/<bus device> */
static struct attribute *vmbus_attrs[] = {
        &dev_attr_id.attr,
        &dev_attr_state.attr,
        &dev_attr_monitor_id.attr,
        &dev_attr_class_id.attr,
        &dev_attr_device_id.attr,
        &dev_attr_modalias.attr,
        &dev_attr_server_monitor_pending.attr,
        &dev_attr_client_monitor_pending.attr,
        &dev_attr_server_monitor_latency.attr,
        &dev_attr_client_monitor_latency.attr,
        &dev_attr_server_monitor_conn_id.attr,
        &dev_attr_client_monitor_conn_id.attr,
        &dev_attr_out_intr_mask.attr,
        &dev_attr_out_read_index.attr,
        &dev_attr_out_write_index.attr,
        &dev_attr_out_read_bytes_avail.attr,
        &dev_attr_out_write_bytes_avail.attr,
        &dev_attr_in_intr_mask.attr,
        &dev_attr_in_read_index.attr,
        &dev_attr_in_write_index.attr,
        &dev_attr_in_read_bytes_avail.attr,
        &dev_attr_in_write_bytes_avail.attr,
        NULL,
};
ATTRIBUTE_GROUPS(vmbus);

/*
 * 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_groups =           vmbus_groups,
};

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
                 */
                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;

        page_addr = hv_context.synic_event_page[cpu];
        if (page_addr == NULL)
                return IRQ_NONE;

        event = (union hv_synic_event_flags *)page_addr +
                                         VMBUS_MESSAGE_SINT;
        /*
         * 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.
         */

        if ((vmbus_proto_version == VERSION_WS2008) ||
                (vmbus_proto_version == VERSION_WIN7)) {

                /* 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;
                }
        } else {
                /*
                 * Our host is win8 or above. The signaling mechanism
                 * has changed and we can directly look at the event page.
                 * If bit n is set then we have an interrup on the channel
                 * whose id is n.
                 */
                handled = true;
        }

        if (handled)
                tasklet_schedule(hv_context.event_dpc[cpu]);


        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 interrupt flow handler:
 * vmbus interrupts can concurrently occur on multiple CPUs and
 * can be handled concurrently.
 */

static void vmbus_flow_handler(unsigned int irq, struct irq_desc *desc)
{
        kstat_incr_irqs_this_cpu(irq, desc);

        desc->action->handler(irq, desc->action->dev_id);
}

/*
 * 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;

        /* 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);

        ret = bus_register(&hv_bus);
        if (ret)
                goto err_cleanup;

        ret = request_irq(irq, vmbus_isr, 0, driver_name, hv_acpi_dev);

        if (ret != 0) {
                pr_err("Unable to request IRQ %d\n",
                           irq);
                goto err_unregister;
        }

        /*
         * Vmbus interrupts can be handled concurrently on
         * different CPUs. Establish an appropriate interrupt flow
         * handler that can support this model.
         */
        irq_set_handler(irq, vmbus_flow_handler);

        /*
         * Register our interrupt handler.
         */
        hv_register_vmbus_handler(irq, vmbus_isr);

        ret = hv_synic_alloc();
        if (ret)
                goto err_alloc;
        /*
         * Initialize the per-cpu interrupt state and
         * connect to the host.
         */
        on_each_cpu(hv_synic_init, NULL, 1);
        ret = vmbus_connect();
        if (ret)
                goto err_alloc;

        vmbus_request_offers();

        return 0;

err_alloc:
        hv_synic_free();
        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);

        ret = vmbus_exists();
        if (ret < 0)
                return ret;

        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);

        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);

        if (!vmbus_exists())
                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_debug("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)
{
        pr_debug("child device %s unregistered\n",
                dev_name(&device_obj->device));

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

        if (x86_hyper != &x86_hyper_ms_hyperv)
                return -ENODEV;

        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);
        hv_acpi_dev = NULL;
        return ret;
}

static void __exit vmbus_exit(void)
{

        free_irq(irq, hv_acpi_dev);
        vmbus_free_channels();
        bus_unregister(&hv_bus);
        hv_cleanup();
        acpi_bus_unregister_driver(&vmbus_acpi_driver);
}


MODULE_LICENSE("GPL");

subsys_initcall(hv_acpi_init);
module_exit(vmbus_exit);