/* sunvdc.c: Sun LDOM Virtual Disk Client.
   *

   * Copyright (C) 2007, 2008 David S. Miller <davem@davemloft.net>

   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/types.h>
  #include <linux/blkdev.h>
  #include <linux/hdreg.h>
  #include <linux/genhd.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/delay.h>
  #include <linux/init.h>
  #include <linux/list.h>

  #include <linux/scatterlist.h>

  
  #include <asm/vio.h>
  #include <asm/ldc.h>
  
  #define DRV_MODULE_NAME		"sunvdc"
  #define PFX DRV_MODULE_NAME	": "
  #define DRV_MODULE_VERSION	"1.0"
  #define DRV_MODULE_RELDATE	"June 25, 2007"

  static char version[] =

  	DRV_MODULE_NAME ".c:v" DRV_MODULE_VERSION " (" DRV_MODULE_RELDATE ")
  ";
  MODULE_AUTHOR("David S. Miller (davem@davemloft.net)");
  MODULE_DESCRIPTION("Sun LDOM virtual disk client driver");
  MODULE_LICENSE("GPL");
  MODULE_VERSION(DRV_MODULE_VERSION);
  
  #define VDC_TX_RING_SIZE	256
  
  #define WAITING_FOR_LINK_UP	0x01
  #define WAITING_FOR_TX_SPACE	0x02
  #define WAITING_FOR_GEN_CMD	0x04
  #define WAITING_FOR_ANY		-1
  
  struct vdc_req_entry {
  	struct request		*req;
  };
  
  struct vdc_port {
  	struct vio_driver_state	vio;

  	struct gendisk		*disk;
  
  	struct vdc_completion	*cmp;
  
  	u64			req_id;
  	u64			seq;
  	struct vdc_req_entry	rq_arr[VDC_TX_RING_SIZE];
  
  	unsigned long		ring_cookies;
  
  	u64			max_xfer_size;
  	u32			vdisk_block_size;
  
  	/* The server fills these in for us in the disk attribute
  	 * ACK packet.
  	 */
  	u64			operations;
  	u32			vdisk_size;
  	u8			vdisk_type;

  
  	char			disk_name[32];
  
  	struct vio_disk_geom	geom;
  	struct vio_disk_vtoc	label;

  };
  
  static inline struct vdc_port *to_vdc_port(struct vio_driver_state *vio)
  {
  	return container_of(vio, struct vdc_port, vio);
  }

  /* Ordered from largest major to lowest */
  static struct vio_version vdc_versions[] = {
  	{ .major = 1, .minor = 0 },
  };
  
  #define VDCBLK_NAME	"vdisk"
  static int vdc_major;
  #define PARTITION_SHIFT	3
  
  static inline u32 vdc_tx_dring_avail(struct vio_dring_state *dr)
  {
  	return vio_dring_avail(dr, VDC_TX_RING_SIZE);
  }
  
  static int vdc_getgeo(struct block_device *bdev, struct hd_geometry *geo)
  {
  	struct gendisk *disk = bdev->bd_disk;
  	struct vdc_port *port = disk->private_data;
  
  	geo->heads = (u8) port->geom.num_hd;
  	geo->sectors = (u8) port->geom.num_sec;
  	geo->cylinders = port->geom.num_cyl;
  
  	return 0;
  }

  static const struct block_device_operations vdc_fops = {

  	.owner		= THIS_MODULE,
  	.getgeo		= vdc_getgeo,
  };
  
  static void vdc_finish(struct vio_driver_state *vio, int err, int waiting_for)
  {
  	if (vio->cmp &&
  	    (waiting_for == -1 ||
  	     vio->cmp->waiting_for == waiting_for)) {
  		vio->cmp->err = err;
  		complete(&vio->cmp->com);
  		vio->cmp = NULL;
  	}
  }
  
  static void vdc_handshake_complete(struct vio_driver_state *vio)
  {
  	vdc_finish(vio, 0, WAITING_FOR_LINK_UP);
  }
  
  static int vdc_handle_unknown(struct vdc_port *port, void *arg)
  {
  	struct vio_msg_tag *pkt = arg;
  
  	printk(KERN_ERR PFX "Received unknown msg [%02x:%02x:%04x:%08x]
  ",
  	       pkt->type, pkt->stype, pkt->stype_env, pkt->sid);
  	printk(KERN_ERR PFX "Resetting connection.
  ");
  
  	ldc_disconnect(port->vio.lp);
  
  	return -ECONNRESET;
  }
  
  static int vdc_send_attr(struct vio_driver_state *vio)
  {
  	struct vdc_port *port = to_vdc_port(vio);
  	struct vio_disk_attr_info pkt;
  
  	memset(&pkt, 0, sizeof(pkt));
  
  	pkt.tag.type = VIO_TYPE_CTRL;
  	pkt.tag.stype = VIO_SUBTYPE_INFO;
  	pkt.tag.stype_env = VIO_ATTR_INFO;
  	pkt.tag.sid = vio_send_sid(vio);
  
  	pkt.xfer_mode = VIO_DRING_MODE;
  	pkt.vdisk_block_size = port->vdisk_block_size;
  	pkt.max_xfer_size = port->max_xfer_size;

  	viodbg(HS, "SEND ATTR xfer_mode[0x%x] blksz[%u] max_xfer[%llu]
  ",

  	       pkt.xfer_mode, pkt.vdisk_block_size, pkt.max_xfer_size);
  
  	return vio_ldc_send(&port->vio, &pkt, sizeof(pkt));
  }
  
  static int vdc_handle_attr(struct vio_driver_state *vio, void *arg)
  {
  	struct vdc_port *port = to_vdc_port(vio);
  	struct vio_disk_attr_info *pkt = arg;

  	viodbg(HS, "GOT ATTR stype[0x%x] ops[%llx] disk_size[%llu] disk_type[%x] "
  	       "xfer_mode[0x%x] blksz[%u] max_xfer[%llu]
  ",

  	       pkt->tag.stype, pkt->operations,
  	       pkt->vdisk_size, pkt->vdisk_type,
  	       pkt->xfer_mode, pkt->vdisk_block_size,
  	       pkt->max_xfer_size);
  
  	if (pkt->tag.stype == VIO_SUBTYPE_ACK) {
  		switch (pkt->vdisk_type) {
  		case VD_DISK_TYPE_DISK:
  		case VD_DISK_TYPE_SLICE:
  			break;
  
  		default:
  			printk(KERN_ERR PFX "%s: Bogus vdisk_type 0x%x
  ",
  			       vio->name, pkt->vdisk_type);
  			return -ECONNRESET;
  		}
  
  		if (pkt->vdisk_block_size > port->vdisk_block_size) {
  			printk(KERN_ERR PFX "%s: BLOCK size increased "
  			       "%u --> %u
  ",
  			       vio->name,
  			       port->vdisk_block_size, pkt->vdisk_block_size);
  			return -ECONNRESET;
  		}
  
  		port->operations = pkt->operations;
  		port->vdisk_size = pkt->vdisk_size;
  		port->vdisk_type = pkt->vdisk_type;
  		if (pkt->max_xfer_size < port->max_xfer_size)
  			port->max_xfer_size = pkt->max_xfer_size;
  		port->vdisk_block_size = pkt->vdisk_block_size;
  		return 0;
  	} else {
  		printk(KERN_ERR PFX "%s: Attribute NACK
  ", vio->name);
  
  		return -ECONNRESET;
  	}
  }
  
  static void vdc_end_special(struct vdc_port *port, struct vio_disk_desc *desc)
  {
  	int err = desc->status;
  
  	vdc_finish(&port->vio, -err, WAITING_FOR_GEN_CMD);
  }

  static void vdc_end_one(struct vdc_port *port, struct vio_dring_state *dr,
  			unsigned int index)
  {
  	struct vio_disk_desc *desc = vio_dring_entry(dr, index);
  	struct vdc_req_entry *rqe = &port->rq_arr[index];
  	struct request *req;
  
  	if (unlikely(desc->hdr.state != VIO_DESC_DONE))
  		return;
  
  	ldc_unmap(port->vio.lp, desc->cookies, desc->ncookies);
  	desc->hdr.state = VIO_DESC_FREE;
  	dr->cons = (index + 1) & (VDC_TX_RING_SIZE - 1);
  
  	req = rqe->req;
  	if (req == NULL) {
  		vdc_end_special(port, desc);
  		return;
  	}
  
  	rqe->req = NULL;

  	__blk_end_request(req, (desc->status ? -EIO : 0), desc->size);

  
  	if (blk_queue_stopped(port->disk->queue))
  		blk_start_queue(port->disk->queue);
  }
  
  static int vdc_ack(struct vdc_port *port, void *msgbuf)
  {
  	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  	struct vio_dring_data *pkt = msgbuf;
  
  	if (unlikely(pkt->dring_ident != dr->ident ||
  		     pkt->start_idx != pkt->end_idx ||
  		     pkt->start_idx >= VDC_TX_RING_SIZE))
  		return 0;
  
  	vdc_end_one(port, dr, pkt->start_idx);
  
  	return 0;
  }
  
  static int vdc_nack(struct vdc_port *port, void *msgbuf)
  {
  	/* XXX Implement me XXX */
  	return 0;
  }
  
  static void vdc_event(void *arg, int event)
  {
  	struct vdc_port *port = arg;
  	struct vio_driver_state *vio = &port->vio;
  	unsigned long flags;
  	int err;
  
  	spin_lock_irqsave(&vio->lock, flags);
  
  	if (unlikely(event == LDC_EVENT_RESET ||
  		     event == LDC_EVENT_UP)) {
  		vio_link_state_change(vio, event);
  		spin_unlock_irqrestore(&vio->lock, flags);
  		return;
  	}
  
  	if (unlikely(event != LDC_EVENT_DATA_READY)) {
  		printk(KERN_WARNING PFX "Unexpected LDC event %d
  ", event);
  		spin_unlock_irqrestore(&vio->lock, flags);
  		return;
  	}
  
  	err = 0;
  	while (1) {
  		union {
  			struct vio_msg_tag tag;
  			u64 raw[8];
  		} msgbuf;
  
  		err = ldc_read(vio->lp, &msgbuf, sizeof(msgbuf));
  		if (unlikely(err < 0)) {
  			if (err == -ECONNRESET)
  				vio_conn_reset(vio);
  			break;
  		}
  		if (err == 0)
  			break;
  		viodbg(DATA, "TAG [%02x:%02x:%04x:%08x]
  ",
  		       msgbuf.tag.type,
  		       msgbuf.tag.stype,
  		       msgbuf.tag.stype_env,
  		       msgbuf.tag.sid);
  		err = vio_validate_sid(vio, &msgbuf.tag);
  		if (err < 0)
  			break;
  
  		if (likely(msgbuf.tag.type == VIO_TYPE_DATA)) {
  			if (msgbuf.tag.stype == VIO_SUBTYPE_ACK)
  				err = vdc_ack(port, &msgbuf);
  			else if (msgbuf.tag.stype == VIO_SUBTYPE_NACK)
  				err = vdc_nack(port, &msgbuf);
  			else
  				err = vdc_handle_unknown(port, &msgbuf);
  		} else if (msgbuf.tag.type == VIO_TYPE_CTRL) {
  			err = vio_control_pkt_engine(vio, &msgbuf);
  		} else {
  			err = vdc_handle_unknown(port, &msgbuf);
  		}
  		if (err < 0)
  			break;
  	}
  	if (err < 0)
  		vdc_finish(&port->vio, err, WAITING_FOR_ANY);
  	spin_unlock_irqrestore(&vio->lock, flags);
  }
  
  static int __vdc_tx_trigger(struct vdc_port *port)
  {
  	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  	struct vio_dring_data hdr = {
  		.tag = {
  			.type		= VIO_TYPE_DATA,
  			.stype		= VIO_SUBTYPE_INFO,
  			.stype_env	= VIO_DRING_DATA,
  			.sid		= vio_send_sid(&port->vio),
  		},
  		.dring_ident		= dr->ident,
  		.start_idx		= dr->prod,
  		.end_idx		= dr->prod,
  	};
  	int err, delay;
  
  	hdr.seq = dr->snd_nxt;
  	delay = 1;
  	do {
  		err = vio_ldc_send(&port->vio, &hdr, sizeof(hdr));
  		if (err > 0) {
  			dr->snd_nxt++;
  			break;
  		}
  		udelay(delay);
  		if ((delay <<= 1) > 128)
  			delay = 128;
  	} while (err == -EAGAIN);
  
  	return err;
  }
  
  static int __send_request(struct request *req)
  {
  	struct vdc_port *port = req->rq_disk->private_data;
  	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  	struct scatterlist sg[port->ring_cookies];
  	struct vdc_req_entry *rqe;
  	struct vio_disk_desc *desc;
  	unsigned int map_perm;
  	int nsg, err, i;
  	u64 len;
  	u8 op;
  
  	map_perm = LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;
  
  	if (rq_data_dir(req) == READ) {
  		map_perm |= LDC_MAP_W;
  		op = VD_OP_BREAD;
  	} else {
  		map_perm |= LDC_MAP_R;
  		op = VD_OP_BWRITE;
  	}

  	sg_init_table(sg, port->ring_cookies);

  	nsg = blk_rq_map_sg(req->q, req, sg);
  
  	len = 0;
  	for (i = 0; i < nsg; i++)
  		len += sg[i].length;
  
  	if (unlikely(vdc_tx_dring_avail(dr) < 1)) {
  		blk_stop_queue(port->disk->queue);
  		err = -ENOMEM;
  		goto out;
  	}
  
  	desc = vio_dring_cur(dr);
  
  	err = ldc_map_sg(port->vio.lp, sg, nsg,
  			 desc->cookies, port->ring_cookies,
  			 map_perm);
  	if (err < 0) {
  		printk(KERN_ERR PFX "ldc_map_sg() failure, err=%d.
  ", err);
  		return err;
  	}
  
  	rqe = &port->rq_arr[dr->prod];
  	rqe->req = req;
  
  	desc->hdr.ack = VIO_ACK_ENABLE;
  	desc->req_id = port->req_id;
  	desc->operation = op;
  	if (port->vdisk_type == VD_DISK_TYPE_DISK) {

  		desc->slice = 0xff;

  	} else {
  		desc->slice = 0;
  	}
  	desc->status = ~0;

  	desc->offset = (blk_rq_pos(req) << 9) / port->vdisk_block_size;

  	desc->size = len;
  	desc->ncookies = err;
  
  	/* This has to be a non-SMP write barrier because we are writing
  	 * to memory which is shared with the peer LDOM.
  	 */
  	wmb();
  	desc->hdr.state = VIO_DESC_READY;
  
  	err = __vdc_tx_trigger(port);
  	if (err < 0) {
  		printk(KERN_ERR PFX "vdc_tx_trigger() failure, err=%d
  ", err);
  	} else {
  		port->req_id++;
  		dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
  	}
  out:
  
  	return err;
  }

  static void do_vdc_request(struct request_queue *q)

  {
  	while (1) {

  		struct request *req = blk_fetch_request(q);

  
  		if (!req)
  			break;

  		if (__send_request(req) < 0)

  			__blk_end_request_all(req, -EIO);

  	}
  }
  
  static int generic_request(struct vdc_port *port, u8 op, void *buf, int len)
  {
  	struct vio_dring_state *dr;
  	struct vio_completion comp;
  	struct vio_disk_desc *desc;
  	unsigned int map_perm;
  	unsigned long flags;
  	int op_len, err;
  	void *req_buf;

  	if (!(((u64)1 << (u64)op) & port->operations))

  		return -EOPNOTSUPP;
  
  	switch (op) {
  	case VD_OP_BREAD:
  	case VD_OP_BWRITE:
  	default:
  		return -EINVAL;
  
  	case VD_OP_FLUSH:
  		op_len = 0;
  		map_perm = 0;
  		break;
  
  	case VD_OP_GET_WCE:
  		op_len = sizeof(u32);
  		map_perm = LDC_MAP_W;
  		break;
  
  	case VD_OP_SET_WCE:
  		op_len = sizeof(u32);
  		map_perm = LDC_MAP_R;
  		break;
  
  	case VD_OP_GET_VTOC:
  		op_len = sizeof(struct vio_disk_vtoc);
  		map_perm = LDC_MAP_W;
  		break;
  
  	case VD_OP_SET_VTOC:
  		op_len = sizeof(struct vio_disk_vtoc);
  		map_perm = LDC_MAP_R;
  		break;
  
  	case VD_OP_GET_DISKGEOM:
  		op_len = sizeof(struct vio_disk_geom);
  		map_perm = LDC_MAP_W;
  		break;
  
  	case VD_OP_SET_DISKGEOM:
  		op_len = sizeof(struct vio_disk_geom);
  		map_perm = LDC_MAP_R;
  		break;
  
  	case VD_OP_SCSICMD:
  		op_len = 16;
  		map_perm = LDC_MAP_RW;
  		break;
  
  	case VD_OP_GET_DEVID:
  		op_len = sizeof(struct vio_disk_devid);
  		map_perm = LDC_MAP_W;
  		break;
  
  	case VD_OP_GET_EFI:
  	case VD_OP_SET_EFI:
  		return -EOPNOTSUPP;
  		break;
  	};
  
  	map_perm |= LDC_MAP_SHADOW | LDC_MAP_DIRECT | LDC_MAP_IO;
  
  	op_len = (op_len + 7) & ~7;
  	req_buf = kzalloc(op_len, GFP_KERNEL);
  	if (!req_buf)
  		return -ENOMEM;
  
  	if (len > op_len)
  		len = op_len;
  
  	if (map_perm & LDC_MAP_R)
  		memcpy(req_buf, buf, len);
  
  	spin_lock_irqsave(&port->vio.lock, flags);
  
  	dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  
  	/* XXX If we want to use this code generically we have to
  	 * XXX handle TX ring exhaustion etc.
  	 */
  	desc = vio_dring_cur(dr);
  
  	err = ldc_map_single(port->vio.lp, req_buf, op_len,
  			     desc->cookies, port->ring_cookies,
  			     map_perm);
  	if (err < 0) {
  		spin_unlock_irqrestore(&port->vio.lock, flags);
  		kfree(req_buf);
  		return err;
  	}
  
  	init_completion(&comp.com);
  	comp.waiting_for = WAITING_FOR_GEN_CMD;
  	port->vio.cmp = &comp;
  
  	desc->hdr.ack = VIO_ACK_ENABLE;
  	desc->req_id = port->req_id;
  	desc->operation = op;
  	desc->slice = 0;
  	desc->status = ~0;
  	desc->offset = 0;
  	desc->size = op_len;
  	desc->ncookies = err;
  
  	/* This has to be a non-SMP write barrier because we are writing
  	 * to memory which is shared with the peer LDOM.
  	 */
  	wmb();
  	desc->hdr.state = VIO_DESC_READY;
  
  	err = __vdc_tx_trigger(port);
  	if (err >= 0) {
  		port->req_id++;
  		dr->prod = (dr->prod + 1) & (VDC_TX_RING_SIZE - 1);
  		spin_unlock_irqrestore(&port->vio.lock, flags);
  
  		wait_for_completion(&comp.com);
  		err = comp.err;
  	} else {
  		port->vio.cmp = NULL;
  		spin_unlock_irqrestore(&port->vio.lock, flags);
  	}
  
  	if (map_perm & LDC_MAP_W)
  		memcpy(buf, req_buf, len);
  
  	kfree(req_buf);
  
  	return err;
  }

  static int vdc_alloc_tx_ring(struct vdc_port *port)

  {
  	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  	unsigned long len, entry_size;
  	int ncookies;
  	void *dring;
  
  	entry_size = sizeof(struct vio_disk_desc) +
  		(sizeof(struct ldc_trans_cookie) * port->ring_cookies);
  	len = (VDC_TX_RING_SIZE * entry_size);
  
  	ncookies = VIO_MAX_RING_COOKIES;
  	dring = ldc_alloc_exp_dring(port->vio.lp, len,
  				    dr->cookies, &ncookies,
  				    (LDC_MAP_SHADOW |
  				     LDC_MAP_DIRECT |
  				     LDC_MAP_RW));
  	if (IS_ERR(dring))
  		return PTR_ERR(dring);
  
  	dr->base = dring;
  	dr->entry_size = entry_size;
  	dr->num_entries = VDC_TX_RING_SIZE;
  	dr->prod = dr->cons = 0;
  	dr->pending = VDC_TX_RING_SIZE;
  	dr->ncookies = ncookies;
  
  	return 0;
  }
  
  static void vdc_free_tx_ring(struct vdc_port *port)
  {
  	struct vio_dring_state *dr = &port->vio.drings[VIO_DRIVER_TX_RING];
  
  	if (dr->base) {
  		ldc_free_exp_dring(port->vio.lp, dr->base,
  				   (dr->entry_size * dr->num_entries),
  				   dr->cookies, dr->ncookies);
  		dr->base = NULL;
  		dr->entry_size = 0;
  		dr->num_entries = 0;
  		dr->pending = 0;
  		dr->ncookies = 0;
  	}
  }
  
  static int probe_disk(struct vdc_port *port)
  {
  	struct vio_completion comp;
  	struct request_queue *q;
  	struct gendisk *g;
  	int err;
  
  	init_completion(&comp.com);
  	comp.err = 0;
  	comp.waiting_for = WAITING_FOR_LINK_UP;
  	port->vio.cmp = ∁
  
  	vio_port_up(&port->vio);
  
  	wait_for_completion(&comp.com);
  	if (comp.err)
  		return comp.err;
  
  	err = generic_request(port, VD_OP_GET_VTOC,
  			      &port->label, sizeof(port->label));
  	if (err < 0) {
  		printk(KERN_ERR PFX "VD_OP_GET_VTOC returns error %d
  ", err);
  		return err;
  	}
  
  	err = generic_request(port, VD_OP_GET_DISKGEOM,
  			      &port->geom, sizeof(port->geom));
  	if (err < 0) {
  		printk(KERN_ERR PFX "VD_OP_GET_DISKGEOM returns "
  		       "error %d
  ", err);
  		return err;
  	}
  
  	port->vdisk_size = ((u64)port->geom.num_cyl *
  			    (u64)port->geom.num_hd *
  			    (u64)port->geom.num_sec);
  
  	q = blk_init_queue(do_vdc_request, &port->vio.lock);
  	if (!q) {
  		printk(KERN_ERR PFX "%s: Could not allocate queue.
  ",
  		       port->vio.name);
  		return -ENOMEM;
  	}
  	g = alloc_disk(1 << PARTITION_SHIFT);
  	if (!g) {
  		printk(KERN_ERR PFX "%s: Could not allocate gendisk.
  ",
  		       port->vio.name);
  		blk_cleanup_queue(q);
  		return -ENOMEM;
  	}
  
  	port->disk = g;

  	blk_queue_max_segments(q, port->ring_cookies);

  	blk_queue_max_hw_sectors(q, port->max_xfer_size);

  	g->major = vdc_major;

  	g->first_minor = port->vio.vdev->dev_no << PARTITION_SHIFT;

  	strcpy(g->disk_name, port->disk_name);
  
  	g->fops = &vdc_fops;
  	g->queue = q;
  	g->private_data = port;
  	g->driverfs_dev = &port->vio.vdev->dev;
  
  	set_capacity(g, port->vdisk_size);
  
  	printk(KERN_INFO PFX "%s: %u sectors (%u MB)
  ",
  	       g->disk_name,
  	       port->vdisk_size, (port->vdisk_size >> (20 - 9)));
  
  	add_disk(g);
  
  	return 0;
  }
  
  static struct ldc_channel_config vdc_ldc_cfg = {
  	.event		= vdc_event,
  	.mtu		= 64,
  	.mode		= LDC_MODE_UNRELIABLE,
  };
  
  static struct vio_driver_ops vdc_vio_ops = {
  	.send_attr		= vdc_send_attr,
  	.handle_attr		= vdc_handle_attr,
  	.handshake_complete	= vdc_handshake_complete,
  };

  static void print_version(void)

  {
  	static int version_printed;
  
  	if (version_printed++ == 0)
  		printk(KERN_INFO "%s", version);
  }

  static int vdc_port_probe(struct vio_dev *vdev, const struct vio_device_id *id)

  {

  	struct mdesc_handle *hp;

  	struct vdc_port *port;

  	int err;

  	print_version();

  	hp = mdesc_grab();

  	err = -ENODEV;

  	if ((vdev->dev_no << PARTITION_SHIFT) & ~(u64)MINORMASK) {

  		printk(KERN_ERR PFX "Port id [%llu] too large.
  ",

  		       vdev->dev_no);

  		goto err_out_release_mdesc;

  	}
  
  	port = kzalloc(sizeof(*port), GFP_KERNEL);

  	err = -ENOMEM;

  	if (!port) {
  		printk(KERN_ERR PFX "Cannot allocate vdc_port.
  ");

  		goto err_out_release_mdesc;

  	}

  	if (vdev->dev_no >= 26)

  		snprintf(port->disk_name, sizeof(port->disk_name),
  			 VDCBLK_NAME "%c%c",

  			 'a' + ((int)vdev->dev_no / 26) - 1,
  			 'a' + ((int)vdev->dev_no % 26));

  	else
  		snprintf(port->disk_name, sizeof(port->disk_name),

  			 VDCBLK_NAME "%c", 'a' + ((int)vdev->dev_no % 26));

  	err = vio_driver_init(&port->vio, vdev, VDEV_DISK,

  			      vdc_versions, ARRAY_SIZE(vdc_versions),
  			      &vdc_vio_ops, port->disk_name);
  	if (err)
  		goto err_out_free_port;
  
  	port->vdisk_block_size = 512;
  	port->max_xfer_size = ((128 * 1024) / port->vdisk_block_size);
  	port->ring_cookies = ((port->max_xfer_size *
  			       port->vdisk_block_size) / PAGE_SIZE) + 2;
  
  	err = vio_ldc_alloc(&port->vio, &vdc_ldc_cfg, port);
  	if (err)
  		goto err_out_free_port;
  
  	err = vdc_alloc_tx_ring(port);
  	if (err)
  		goto err_out_free_ldc;
  
  	err = probe_disk(port);
  	if (err)
  		goto err_out_free_tx_ring;

  	dev_set_drvdata(&vdev->dev, port);

  	mdesc_release(hp);

  	return 0;
  
  err_out_free_tx_ring:
  	vdc_free_tx_ring(port);
  
  err_out_free_ldc:
  	vio_ldc_free(&port->vio);
  
  err_out_free_port:
  	kfree(port);

  err_out_release_mdesc:
  	mdesc_release(hp);

  	return err;
  }
  
  static int vdc_port_remove(struct vio_dev *vdev)
  {
  	struct vdc_port *port = dev_get_drvdata(&vdev->dev);
  
  	if (port) {
  		del_timer_sync(&port->vio.timer);
  
  		vdc_free_tx_ring(port);
  		vio_ldc_free(&port->vio);
  
  		dev_set_drvdata(&vdev->dev, NULL);
  
  		kfree(port);
  	}
  	return 0;
  }

  static const struct vio_device_id vdc_port_match[] = {

  	{
  		.type = "vdc-port",
  	},
  	{},
  };

  MODULE_DEVICE_TABLE(vio, vdc_port_match);

  
  static struct vio_driver vdc_port_driver = {
  	.id_table	= vdc_port_match,
  	.probe		= vdc_port_probe,
  	.remove		= vdc_port_remove,

  	.name		= "vdc_port",

  };

  static int __init vdc_init(void)
  {
  	int err;
  
  	err = register_blkdev(0, VDCBLK_NAME);
  	if (err < 0)
  		goto out_err;
  
  	vdc_major = err;

  
  	err = vio_register_driver(&vdc_port_driver);
  	if (err)

  		goto out_unregister_blkdev;

  
  	return 0;

  out_unregister_blkdev:
  	unregister_blkdev(vdc_major, VDCBLK_NAME);
  	vdc_major = 0;
  
  out_err:
  	return err;
  }
  
  static void __exit vdc_exit(void)
  {
  	vio_unregister_driver(&vdc_port_driver);

  	unregister_blkdev(vdc_major, VDCBLK_NAME);
  }
  
  module_init(vdc_init);
  module_exit(vdc_exit);