Linux-2.6.12-rc2

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / block / viodasd.c

/* -*- linux-c -*-
 * viodasd.c
 *  Authors: Dave Boutcher <boutcher@us.ibm.com>
 *           Ryan Arnold <ryanarn@us.ibm.com>
 *           Colin Devilbiss <devilbis@us.ibm.com>
 *           Stephen Rothwell <sfr@au1.ibm.com>
 *
 * (C) Copyright 2000-2004 IBM Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that 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
 *
 * This routine provides access to disk space (termed "DASD" in historical
 * IBM terms) owned and managed by an OS/400 partition running on the
 * same box as this Linux partition.
 *
 * All disk operations are performed by sending messages back and forth to
 * the OS/400 partition.
 */
#include <linux/major.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/genhd.h>
#include <linux/hdreg.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/dma-mapping.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/kernel.h>

#include <asm/uaccess.h>
#include <asm/vio.h>
#include <asm/iSeries/HvTypes.h>
#include <asm/iSeries/HvLpEvent.h>
#include <asm/iSeries/HvLpConfig.h>
#include <asm/iSeries/vio.h>

MODULE_DESCRIPTION("iSeries Virtual DASD");
MODULE_AUTHOR("Dave Boutcher");
MODULE_LICENSE("GPL");

/*
 * We only support 7 partitions per physical disk....so with minor
 * numbers 0-255 we get a maximum of 32 disks.
 */
#define VIOD_GENHD_NAME         "iseries/vd"
#define VIOD_GENHD_DEVFS_NAME   "iseries/disc"

#define VIOD_VERS               "1.64"

#define VIOD_KERN_WARNING       KERN_WARNING "viod: "
#define VIOD_KERN_INFO          KERN_INFO "viod: "

enum {
        PARTITION_SHIFT = 3,
        MAX_DISKNO = HVMAXARCHITECTEDVIRTUALDISKS,
        MAX_DISK_NAME = sizeof(((struct gendisk *)0)->disk_name)
};

static DEFINE_SPINLOCK(viodasd_spinlock);

#define VIOMAXREQ               16
#define VIOMAXBLOCKDMA          12

#define DEVICE_NO(cell) ((struct viodasd_device *)(cell) - &viodasd_devices[0])

struct open_data {
        u64     disk_size;
        u16     max_disk;
        u16     cylinders;
        u16     tracks;
        u16     sectors;
        u16     bytes_per_sector;
};

struct rw_data {
        u64     offset;
        struct {
                u32     token;
                u32     reserved;
                u64     len;
        } dma_info[VIOMAXBLOCKDMA];
};

struct vioblocklpevent {
        struct HvLpEvent        event;
        u32                     reserved;
        u16                     version;
        u16                     sub_result;
        u16                     disk;
        u16                     flags;
        union {
                struct open_data        open_data;
                struct rw_data          rw_data;
                u64                     changed;
        } u;
};

#define vioblockflags_ro   0x0001

enum vioblocksubtype {
        vioblockopen = 0x0001,
        vioblockclose = 0x0002,
        vioblockread = 0x0003,
        vioblockwrite = 0x0004,
        vioblockflush = 0x0005,
        vioblockcheck = 0x0007
};

struct viodasd_waitevent {
        struct completion       com;
        int                     rc;
        u16                     sub_result;
        int                     max_disk;       /* open */
};

static const struct vio_error_entry viodasd_err_table[] = {
        { 0x0201, EINVAL, "Invalid Range" },
        { 0x0202, EINVAL, "Invalid Token" },
        { 0x0203, EIO, "DMA Error" },
        { 0x0204, EIO, "Use Error" },
        { 0x0205, EIO, "Release Error" },
        { 0x0206, EINVAL, "Invalid Disk" },
        { 0x0207, EBUSY, "Cant Lock" },
        { 0x0208, EIO, "Already Locked" },
        { 0x0209, EIO, "Already Unlocked" },
        { 0x020A, EIO, "Invalid Arg" },
        { 0x020B, EIO, "Bad IFS File" },
        { 0x020C, EROFS, "Read Only Device" },
        { 0x02FF, EIO, "Internal Error" },
        { 0x0000, 0, NULL },
};

/*
 * Figure out the biggest I/O request (in sectors) we can accept
 */
#define VIODASD_MAXSECTORS (4096 / 512 * VIOMAXBLOCKDMA)

/*
 * Number of disk I/O requests we've sent to OS/400
 */
static int num_req_outstanding;

/*
 * This is our internal structure for keeping track of disk devices
 */
struct viodasd_device {
        u16             cylinders;
        u16             tracks;
        u16             sectors;
        u16             bytes_per_sector;
        u64             size;
        int             read_only;
        spinlock_t      q_lock;
        struct gendisk  *disk;
        struct device   *dev;
} viodasd_devices[MAX_DISKNO];

/*
 * External open entry point.
 */
static int viodasd_open(struct inode *ino, struct file *fil)
{
        struct viodasd_device *d = ino->i_bdev->bd_disk->private_data;
        HvLpEvent_Rc hvrc;
        struct viodasd_waitevent we;
        u16 flags = 0;

        if (d->read_only) {
                if ((fil != NULL) && (fil->f_mode & FMODE_WRITE))
                        return -EROFS;
                flags = vioblockflags_ro;
        }

        init_completion(&we.com);

        /* Send the open event to OS/400 */
        hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_blockio | vioblockopen,
                        HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(viopath_hostLp),
                        viopath_targetinst(viopath_hostLp),
                        (u64)(unsigned long)&we, VIOVERSION << 16,
                        ((u64)DEVICE_NO(d) << 48) | ((u64)flags << 32),
                        0, 0, 0);
        if (hvrc != 0) {
                printk(VIOD_KERN_WARNING "HV open failed %d\n", (int)hvrc);
                return -EIO;
        }

        wait_for_completion(&we.com);

        /* Check the return code */
        if (we.rc != 0) {
                const struct vio_error_entry *err =
                        vio_lookup_rc(viodasd_err_table, we.sub_result);

                printk(VIOD_KERN_WARNING
                                "bad rc opening disk: %d:0x%04x (%s)\n",
                                (int)we.rc, we.sub_result, err->msg);
                return -EIO;
        }

        return 0;
}

/*
 * External release entry point.
 */
static int viodasd_release(struct inode *ino, struct file *fil)
{
        struct viodasd_device *d = ino->i_bdev->bd_disk->private_data;
        HvLpEvent_Rc hvrc;

        /* Send the event to OS/400.  We DON'T expect a response */
        hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_blockio | vioblockclose,
                        HvLpEvent_AckInd_NoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(viopath_hostLp),
                        viopath_targetinst(viopath_hostLp),
                        0, VIOVERSION << 16,
                        ((u64)DEVICE_NO(d) << 48) /* | ((u64)flags << 32) */,
                        0, 0, 0);
        if (hvrc != 0)
                printk(VIOD_KERN_WARNING "HV close call failed %d\n",
                                (int)hvrc);
        return 0;
}


/* External ioctl entry point.
 */
static int viodasd_ioctl(struct inode *ino, struct file *fil,
                         unsigned int cmd, unsigned long arg)
{
        unsigned char sectors;
        unsigned char heads;
        unsigned short cylinders;
        struct hd_geometry *geo;
        struct gendisk *gendisk;
        struct viodasd_device *d;

        switch (cmd) {
        case HDIO_GETGEO:
                geo = (struct hd_geometry *)arg;
                if (geo == NULL)
                        return -EINVAL;
                if (!access_ok(VERIFY_WRITE, geo, sizeof(*geo)))
                        return -EFAULT;
                gendisk = ino->i_bdev->bd_disk;
                d = gendisk->private_data;
                sectors = d->sectors;
                if (sectors == 0)
                        sectors = 32;
                heads = d->tracks;
                if (heads == 0)
                        heads = 64;
                cylinders = d->cylinders;
                if (cylinders == 0)
                        cylinders = get_capacity(gendisk) / (sectors * heads);
                if (__put_user(sectors, &geo->sectors) ||
                    __put_user(heads, &geo->heads) ||
                    __put_user(cylinders, &geo->cylinders) ||
                    __put_user(get_start_sect(ino->i_bdev), &geo->start))
                        return -EFAULT;
                return 0;
        }

        return -EINVAL;
}

/*
 * Our file operations table
 */
static struct block_device_operations viodasd_fops = {
        .owner = THIS_MODULE,
        .open = viodasd_open,
        .release = viodasd_release,
        .ioctl = viodasd_ioctl,
};

/*
 * End a request
 */
static void viodasd_end_request(struct request *req, int uptodate,
                int num_sectors)
{
        if (end_that_request_first(req, uptodate, num_sectors))
                return;
        add_disk_randomness(req->rq_disk);
        end_that_request_last(req);
}

/*
 * Send an actual I/O request to OS/400
 */
static int send_request(struct request *req)
{
        u64 start;
        int direction;
        int nsg;
        u16 viocmd;
        HvLpEvent_Rc hvrc;
        struct vioblocklpevent *bevent;
        struct scatterlist sg[VIOMAXBLOCKDMA];
        int sgindex;
        int statindex;
        struct viodasd_device *d;
        unsigned long flags;

        start = (u64)req->sector << 9;

        if (rq_data_dir(req) == READ) {
                direction = DMA_FROM_DEVICE;
                viocmd = viomajorsubtype_blockio | vioblockread;
                statindex = 0;
        } else {
                direction = DMA_TO_DEVICE;
                viocmd = viomajorsubtype_blockio | vioblockwrite;
                statindex = 1;
        }

        d = req->rq_disk->private_data;

        /* Now build the scatter-gather list */
        nsg = blk_rq_map_sg(req->q, req, sg);
        nsg = dma_map_sg(d->dev, sg, nsg, direction);

        spin_lock_irqsave(&viodasd_spinlock, flags);
        num_req_outstanding++;

        /* This optimization handles a single DMA block */
        if (nsg == 1)
                hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                                HvLpEvent_Type_VirtualIo, viocmd,
                                HvLpEvent_AckInd_DoAck,
                                HvLpEvent_AckType_ImmediateAck,
                                viopath_sourceinst(viopath_hostLp),
                                viopath_targetinst(viopath_hostLp),
                                (u64)(unsigned long)req, VIOVERSION << 16,
                                ((u64)DEVICE_NO(d) << 48), start,
                                ((u64)sg_dma_address(&sg[0])) << 32,
                                sg_dma_len(&sg[0]));
        else {
                bevent = (struct vioblocklpevent *)
                        vio_get_event_buffer(viomajorsubtype_blockio);
                if (bevent == NULL) {
                        printk(VIOD_KERN_WARNING
                               "error allocating disk event buffer\n");
                        goto error_ret;
                }

                /*
                 * Now build up the actual request.  Note that we store
                 * the pointer to the request in the correlation
                 * token so we can match the response up later
                 */
                memset(bevent, 0, sizeof(struct vioblocklpevent));
                bevent->event.xFlags.xValid = 1;
                bevent->event.xFlags.xFunction = HvLpEvent_Function_Int;
                bevent->event.xFlags.xAckInd = HvLpEvent_AckInd_DoAck;
                bevent->event.xFlags.xAckType = HvLpEvent_AckType_ImmediateAck;
                bevent->event.xType = HvLpEvent_Type_VirtualIo;
                bevent->event.xSubtype = viocmd;
                bevent->event.xSourceLp = HvLpConfig_getLpIndex();
                bevent->event.xTargetLp = viopath_hostLp;
                bevent->event.xSizeMinus1 =
                        offsetof(struct vioblocklpevent, u.rw_data.dma_info) +
                        (sizeof(bevent->u.rw_data.dma_info[0]) * nsg) - 1;
                bevent->event.xSourceInstanceId =
                        viopath_sourceinst(viopath_hostLp);
                bevent->event.xTargetInstanceId =
                        viopath_targetinst(viopath_hostLp);
                bevent->event.xCorrelationToken = (u64)req;
                bevent->version = VIOVERSION;
                bevent->disk = DEVICE_NO(d);
                bevent->u.rw_data.offset = start;

                /*
                 * Copy just the dma information from the sg list
                 * into the request
                 */
                for (sgindex = 0; sgindex < nsg; sgindex++) {
                        bevent->u.rw_data.dma_info[sgindex].token =
                                sg_dma_address(&sg[sgindex]);
                        bevent->u.rw_data.dma_info[sgindex].len =
                                sg_dma_len(&sg[sgindex]);
                }

                /* Send the request */
                hvrc = HvCallEvent_signalLpEvent(&bevent->event);
                vio_free_event_buffer(viomajorsubtype_blockio, bevent);
        }

        if (hvrc != HvLpEvent_Rc_Good) {
                printk(VIOD_KERN_WARNING
                       "error sending disk event to OS/400 (rc %d)\n",
                       (int)hvrc);
                goto error_ret;
        }
        spin_unlock_irqrestore(&viodasd_spinlock, flags);
        return 0;

error_ret:
        num_req_outstanding--;
        spin_unlock_irqrestore(&viodasd_spinlock, flags);
        dma_unmap_sg(d->dev, sg, nsg, direction);
        return -1;
}

/*
 * This is the external request processing routine
 */
static void do_viodasd_request(request_queue_t *q)
{
        struct request *req;

        /*
         * If we already have the maximum number of requests
         * outstanding to OS/400 just bail out. We'll come
         * back later.
         */
        while (num_req_outstanding < VIOMAXREQ) {
                req = elv_next_request(q);
                if (req == NULL)
                        return;
                /* dequeue the current request from the queue */
                blkdev_dequeue_request(req);
                /* check that request contains a valid command */
                if (!blk_fs_request(req)) {
                        viodasd_end_request(req, 0, req->hard_nr_sectors);
                        continue;
                }
                /* Try sending the request */
                if (send_request(req) != 0)
                        viodasd_end_request(req, 0, req->hard_nr_sectors);
        }
}

/*
 * Probe a single disk and fill in the viodasd_device structure
 * for it.
 */
static void probe_disk(struct viodasd_device *d)
{
        HvLpEvent_Rc hvrc;
        struct viodasd_waitevent we;
        int dev_no = DEVICE_NO(d);
        struct gendisk *g;
        struct request_queue *q;
        u16 flags = 0;

retry:
        init_completion(&we.com);

        /* Send the open event to OS/400 */
        hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_blockio | vioblockopen,
                        HvLpEvent_AckInd_DoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(viopath_hostLp),
                        viopath_targetinst(viopath_hostLp),
                        (u64)(unsigned long)&we, VIOVERSION << 16,
                        ((u64)dev_no << 48) | ((u64)flags<< 32),
                        0, 0, 0);
        if (hvrc != 0) {
                printk(VIOD_KERN_WARNING "bad rc on HV open %d\n", (int)hvrc);
                return;
        }

        wait_for_completion(&we.com);

        if (we.rc != 0) {
                if (flags != 0)
                        return;
                /* try again with read only flag set */
                flags = vioblockflags_ro;
                goto retry;
        }
        if (we.max_disk > (MAX_DISKNO - 1)) {
                static int warned;

                if (warned == 0) {
                        warned++;
                        printk(VIOD_KERN_INFO
                                "Only examining the first %d "
                                "of %d disks connected\n",
                                MAX_DISKNO, we.max_disk + 1);
                }
        }

        /* Send the close event to OS/400.  We DON'T expect a response */
        hvrc = HvCallEvent_signalLpEventFast(viopath_hostLp,
                        HvLpEvent_Type_VirtualIo,
                        viomajorsubtype_blockio | vioblockclose,
                        HvLpEvent_AckInd_NoAck, HvLpEvent_AckType_ImmediateAck,
                        viopath_sourceinst(viopath_hostLp),
                        viopath_targetinst(viopath_hostLp),
                        0, VIOVERSION << 16,
                        ((u64)dev_no << 48) | ((u64)flags << 32),
                        0, 0, 0);
        if (hvrc != 0) {
                printk(VIOD_KERN_WARNING
                       "bad rc sending event to OS/400 %d\n", (int)hvrc);
                return;
        }
        /* create the request queue for the disk */
        spin_lock_init(&d->q_lock);
        q = blk_init_queue(do_viodasd_request, &d->q_lock);
        if (q == NULL) {
                printk(VIOD_KERN_WARNING "cannot allocate queue for disk %d\n",
                                dev_no);
                return;
        }
        g = alloc_disk(1 << PARTITION_SHIFT);
        if (g == NULL) {
                printk(VIOD_KERN_WARNING
                                "cannot allocate disk structure for disk %d\n",
                                dev_no);
                blk_cleanup_queue(q);
                return;
        }

        d->disk = g;
        blk_queue_max_hw_segments(q, VIOMAXBLOCKDMA);
        blk_queue_max_phys_segments(q, VIOMAXBLOCKDMA);
        blk_queue_max_sectors(q, VIODASD_MAXSECTORS);
        g->major = VIODASD_MAJOR;
        g->first_minor = dev_no << PARTITION_SHIFT;
        if (dev_no >= 26)
                snprintf(g->disk_name, sizeof(g->disk_name),
                                VIOD_GENHD_NAME "%c%c",
                                'a' + (dev_no / 26) - 1, 'a' + (dev_no % 26));
        else
                snprintf(g->disk_name, sizeof(g->disk_name),
                                VIOD_GENHD_NAME "%c", 'a' + (dev_no % 26));
        snprintf(g->devfs_name, sizeof(g->devfs_name),
                        "%s%d", VIOD_GENHD_DEVFS_NAME, dev_no);
        g->fops = &viodasd_fops;
        g->queue = q;
        g->private_data = d;
        g->driverfs_dev = d->dev;
        set_capacity(g, d->size >> 9);

        printk(VIOD_KERN_INFO "disk %d: %lu sectors (%lu MB) "
                        "CHS=%d/%d/%d sector size %d%s\n",
                        dev_no, (unsigned long)(d->size >> 9),
                        (unsigned long)(d->size >> 20),
                        (int)d->cylinders, (int)d->tracks,
                        (int)d->sectors, (int)d->bytes_per_sector,
                        d->read_only ? " (RO)" : "");

        /* register us in the global list */
        add_disk(g);
}

/* returns the total number of scatterlist elements converted */
static int block_event_to_scatterlist(const struct vioblocklpevent *bevent,
                struct scatterlist *sg, int *total_len)
{
        int i, numsg;
        const struct rw_data *rw_data = &bevent->u.rw_data;
        static const int offset =
                offsetof(struct vioblocklpevent, u.rw_data.dma_info);
        static const int element_size = sizeof(rw_data->dma_info[0]);

        numsg = ((bevent->event.xSizeMinus1 + 1) - offset) / element_size;
        if (numsg > VIOMAXBLOCKDMA)
                numsg = VIOMAXBLOCKDMA;

        *total_len = 0;
        memset(sg, 0, sizeof(sg[0]) * VIOMAXBLOCKDMA);

        for (i = 0; (i < numsg) && (rw_data->dma_info[i].len > 0); ++i) {
                sg_dma_address(&sg[i]) = rw_data->dma_info[i].token;
                sg_dma_len(&sg[i]) = rw_data->dma_info[i].len;
                *total_len += rw_data->dma_info[i].len;
        }
        return i;
}

/*
 * Restart all queues, starting with the one _after_ the disk given,
 * thus reducing the chance of starvation of higher numbered disks.
 */
static void viodasd_restart_all_queues_starting_from(int first_index)
{
        int i;

        for (i = first_index + 1; i < MAX_DISKNO; ++i)
                if (viodasd_devices[i].disk)
                        blk_run_queue(viodasd_devices[i].disk->queue);
        for (i = 0; i <= first_index; ++i)
                if (viodasd_devices[i].disk)
                        blk_run_queue(viodasd_devices[i].disk->queue);
}

/*
 * For read and write requests, decrement the number of outstanding requests,
 * Free the DMA buffers we allocated.
 */
static int viodasd_handle_read_write(struct vioblocklpevent *bevent)
{
        int num_sg, num_sect, pci_direction, total_len;
        struct request *req;
        struct scatterlist sg[VIOMAXBLOCKDMA];
        struct HvLpEvent *event = &bevent->event;
        unsigned long irq_flags;
        struct viodasd_device *d;
        int error;
        spinlock_t *qlock;

        num_sg = block_event_to_scatterlist(bevent, sg, &total_len);
        num_sect = total_len >> 9;
        if (event->xSubtype == (viomajorsubtype_blockio | vioblockread))
                pci_direction = DMA_FROM_DEVICE;
        else
                pci_direction = DMA_TO_DEVICE;
        req = (struct request *)bevent->event.xCorrelationToken;
        d = req->rq_disk->private_data;

        dma_unmap_sg(d->dev, sg, num_sg, pci_direction);

        /*
         * Since this is running in interrupt mode, we need to make sure
         * we're not stepping on any global I/O operations
         */
        spin_lock_irqsave(&viodasd_spinlock, irq_flags);
        num_req_outstanding--;
        spin_unlock_irqrestore(&viodasd_spinlock, irq_flags);

        error = event->xRc != HvLpEvent_Rc_Good;
        if (error) {
                const struct vio_error_entry *err;
                err = vio_lookup_rc(viodasd_err_table, bevent->sub_result);
                printk(VIOD_KERN_WARNING "read/write error %d:0x%04x (%s)\n",
                                event->xRc, bevent->sub_result, err->msg);
                num_sect = req->hard_nr_sectors;
        }
        qlock = req->q->queue_lock;
        spin_lock_irqsave(qlock, irq_flags);
        viodasd_end_request(req, !error, num_sect);
        spin_unlock_irqrestore(qlock, irq_flags);

        /* Finally, try to get more requests off of this device's queue */
        viodasd_restart_all_queues_starting_from(DEVICE_NO(d));

        return 0;
}

/* This routine handles incoming block LP events */
static void handle_block_event(struct HvLpEvent *event)
{
        struct vioblocklpevent *bevent = (struct vioblocklpevent *)event;
        struct viodasd_waitevent *pwe;

        if (event == NULL)
                /* Notification that a partition went away! */
                return;
        /* First, we should NEVER get an int here...only acks */
        if (event->xFlags.xFunction == HvLpEvent_Function_Int) {
                printk(VIOD_KERN_WARNING
                       "Yikes! got an int in viodasd event handler!\n");
                if (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck) {
                        event->xRc = HvLpEvent_Rc_InvalidSubtype;
                        HvCallEvent_ackLpEvent(event);
                }
        }

        switch (event->xSubtype & VIOMINOR_SUBTYPE_MASK) {
        case vioblockopen:
                /*
                 * Handle a response to an open request.  We get all the
                 * disk information in the response, so update it.  The
                 * correlation token contains a pointer to a waitevent
                 * structure that has a completion in it.  update the
                 * return code in the waitevent structure and post the
                 * completion to wake up the guy who sent the request
                 */
                pwe = (struct viodasd_waitevent *)event->xCorrelationToken;
                pwe->rc = event->xRc;
                pwe->sub_result = bevent->sub_result;
                if (event->xRc == HvLpEvent_Rc_Good) {
                        const struct open_data *data = &bevent->u.open_data;
                        struct viodasd_device *device =
                                &viodasd_devices[bevent->disk];
                        device->read_only =
                                bevent->flags & vioblockflags_ro;
                        device->size = data->disk_size;
                        device->cylinders = data->cylinders;
                        device->tracks = data->tracks;
                        device->sectors = data->sectors;
                        device->bytes_per_sector = data->bytes_per_sector;
                        pwe->max_disk = data->max_disk;
                }
                complete(&pwe->com);
                break;
        case vioblockclose:
                break;
        case vioblockread:
        case vioblockwrite:
                viodasd_handle_read_write(bevent);
                break;

        default:
                printk(VIOD_KERN_WARNING "invalid subtype!");
                if (event->xFlags.xAckInd == HvLpEvent_AckInd_DoAck) {
                        event->xRc = HvLpEvent_Rc_InvalidSubtype;
                        HvCallEvent_ackLpEvent(event);
                }
        }
}

/*
 * Get the driver to reprobe for more disks.
 */
static ssize_t probe_disks(struct device_driver *drv, const char *buf,
                size_t count)
{
        struct viodasd_device *d;

        for (d = viodasd_devices; d < &viodasd_devices[MAX_DISKNO]; d++) {
                if (d->disk == NULL)
                        probe_disk(d);
        }
        return count;
}
static DRIVER_ATTR(probe, S_IWUSR, NULL, probe_disks);

static int viodasd_probe(struct vio_dev *vdev, const struct vio_device_id *id)
{
        struct viodasd_device *d = &viodasd_devices[vdev->unit_address];

        d->dev = &vdev->dev;
        probe_disk(d);
        if (d->disk == NULL)
                return -ENODEV;
        return 0;
}

static int viodasd_remove(struct vio_dev *vdev)
{
        struct viodasd_device *d;

        d = &viodasd_devices[vdev->unit_address];
        if (d->disk) {
                del_gendisk(d->disk);
                blk_cleanup_queue(d->disk->queue);
                put_disk(d->disk);
                d->disk = NULL;
        }
        d->dev = NULL;
        return 0;
}

/**
 * viodasd_device_table: Used by vio.c to match devices that we
 * support.
 */
static struct vio_device_id viodasd_device_table[] __devinitdata = {
        { "viodasd", "" },
        { 0, }
};

MODULE_DEVICE_TABLE(vio, viodasd_device_table);
static struct vio_driver viodasd_driver = {
        .name = "viodasd",
        .id_table = viodasd_device_table,
        .probe = viodasd_probe,
        .remove = viodasd_remove
};

/*
 * Initialize the whole device driver.  Handle module and non-module
 * versions
 */
static int __init viodasd_init(void)
{
        int rc;

        /* Try to open to our host lp */
        if (viopath_hostLp == HvLpIndexInvalid)
                vio_set_hostlp();

        if (viopath_hostLp == HvLpIndexInvalid) {
                printk(VIOD_KERN_WARNING "invalid hosting partition\n");
                return -EIO;
        }

        printk(VIOD_KERN_INFO "vers " VIOD_VERS ", hosting partition %d\n",
                        viopath_hostLp);

        /* register the block device */
        if (register_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME)) {
                printk(VIOD_KERN_WARNING
                                "Unable to get major number %d for %s\n",
                                VIODASD_MAJOR, VIOD_GENHD_NAME);
                return -EIO;
        }
        /* Actually open the path to the hosting partition */
        if (viopath_open(viopath_hostLp, viomajorsubtype_blockio,
                                VIOMAXREQ + 2)) {
                printk(VIOD_KERN_WARNING
                       "error opening path to host partition %d\n",
                       viopath_hostLp);
                unregister_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME);
                return -EIO;
        }

        /* Initialize our request handler */
        vio_setHandler(viomajorsubtype_blockio, handle_block_event);

        rc = vio_register_driver(&viodasd_driver);
        if (rc == 0)
                driver_create_file(&viodasd_driver.driver, &driver_attr_probe);
        return rc;
}
module_init(viodasd_init);

void viodasd_exit(void)
{
        driver_remove_file(&viodasd_driver.driver, &driver_attr_probe);
        vio_unregister_driver(&viodasd_driver);
        vio_clearHandler(viomajorsubtype_blockio);
        unregister_blkdev(VIODASD_MAJOR, VIOD_GENHD_NAME);
        viopath_close(viopath_hostLp, viomajorsubtype_blockio, VIOMAXREQ + 2);
}

module_exit(viodasd_exit);