linux-next/drivers/message/i2o/i2o_block.c

/*
 *	Block OSM
 *
 * 	Copyright (C) 1999-2002	Red Hat Software
 *
 *	Written by Alan Cox, Building Number Three Ltd
 *
 *	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.
 *
 *	For the purpose of avoiding doubt the preferred form of the work
 *	for making modifications shall be a standards compliant form such
 *	gzipped tar and not one requiring a proprietary or patent encumbered
 *	tool to unpack.
 *
 *	Fixes/additions:
 *		Steve Ralston:
 *			Multiple device handling error fixes,
 *			Added a queue depth.
 *		Alan Cox:
 *			FC920 has an rmw bug. Dont or in the end marker.
 *			Removed queue walk, fixed for 64bitness.
 *			Rewrote much of the code over time
 *			Added indirect block lists
 *			Handle 64K limits on many controllers
 *			Don't use indirects on the Promise (breaks)
 *			Heavily chop down the queue depths
 *		Deepak Saxena:
 *			Independent queues per IOP
 *			Support for dynamic device creation/deletion
 *			Code cleanup
 *	    		Support for larger I/Os through merge* functions
 *			(taken from DAC960 driver)
 *		Boji T Kannanthanam:
 *			Set the I2O Block devices to be detected in increasing
 *			order of TIDs during boot.
 *			Search and set the I2O block device that we boot off
 *			from as the first device to be claimed (as /dev/i2o/hda)
 *			Properly attach/detach I2O gendisk structure from the
 *			system gendisk list. The I2O block devices now appear in
 *			/proc/partitions.
 *		Markus Lidel <Markus.Lidel@shadowconnect.com>:
 *			Minor bugfixes for 2.6.
 */

#include <linux/module.h>
#include <linux/i2o.h>

#include <linux/mempool.h>

#include <linux/genhd.h>
#include <linux/blkdev.h>
#include <linux/hdreg.h>

#include "i2o_block.h"

#define OSM_NAME	"block-osm"
#define OSM_VERSION	"$Rev$"
#define OSM_DESCRIPTION	"I2O Block Device OSM"

static struct i2o_driver i2o_block_driver;

/* global Block OSM request mempool */
static struct i2o_block_mempool i2o_blk_req_pool;

/* Block OSM class handling definition */
static struct i2o_class_id i2o_block_class_id[] = {
	{I2O_CLASS_RANDOM_BLOCK_STORAGE},
	{I2O_CLASS_END}
};

/**
 *	i2o_block_device_free - free the memory of the I2O Block device
 *	@dev: I2O Block device, which should be cleaned up
 *
 *	Frees the request queue, gendisk and the i2o_block_device structure.
 */
static void i2o_block_device_free(struct i2o_block_device *dev)
{
	blk_cleanup_queue(dev->gd->queue);

	put_disk(dev->gd);

	kfree(dev);
};

/**
 *	i2o_block_remove - remove the I2O Block device from the system again
 *	@dev: I2O Block device which should be removed
 *
 *	Remove gendisk from system and free all allocated memory.
 *
 *	Always returns 0.
 */
static int i2o_block_remove(struct device *dev)
{
	struct i2o_device *i2o_dev = to_i2o_device(dev);
	struct i2o_block_device *i2o_blk_dev = dev_get_drvdata(dev);

	osm_info("device removed (TID: %03x): %s\n", i2o_dev->lct_data.tid,
		 i2o_blk_dev->gd->disk_name);

	i2o_event_register(i2o_dev, &i2o_block_driver, 0, 0);

	del_gendisk(i2o_blk_dev->gd);

	dev_set_drvdata(dev, NULL);

	i2o_device_claim_release(i2o_dev);

	i2o_block_device_free(i2o_blk_dev);

	return 0;
};

/**
 *	i2o_block_device flush - Flush all dirty data of I2O device dev
 *	@dev: I2O device which should be flushed
 *
 *	Flushes all dirty data on device dev.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_device_flush(struct i2o_device *dev)
{
	struct i2o_message __iomem *msg;
	u32 m;

	m = i2o_msg_get_wait(dev->iop, &msg, I2O_TIMEOUT_MESSAGE_GET);
	if (m == I2O_QUEUE_EMPTY)
		return -ETIMEDOUT;

	writel(FIVE_WORD_MSG_SIZE | SGL_OFFSET_0, &msg->u.head[0]);
	writel(I2O_CMD_BLOCK_CFLUSH << 24 | HOST_TID << 12 | dev->lct_data.tid,
	       &msg->u.head[1]);
	writel(60 << 16, &msg->body[0]);
	osm_debug("Flushing...\n");

	return i2o_msg_post_wait(dev->iop, m, 60);
};

/**
 *	i2o_block_issue_flush - device-flush interface for block-layer
 *	@queue: the request queue of the device which should be flushed
 *	@disk: gendisk
 *	@error_sector: error offset
 *
 *	Helper function to provide flush functionality to block-layer.
 *
 *	Returns 0 on success or negative error code on failure.
 */

static int i2o_block_issue_flush(request_queue_t * queue, struct gendisk *disk,
				 sector_t * error_sector)
{
	struct i2o_block_device *i2o_blk_dev = queue->queuedata;
	int rc = -ENODEV;

	if (likely(i2o_blk_dev))
		rc = i2o_block_device_flush(i2o_blk_dev->i2o_dev);

	return rc;
}

/**
 *	i2o_block_device_mount - Mount (load) the media of device dev
 *	@dev: I2O device which should receive the mount request
 *	@media_id: Media Identifier
 *
 *	Load a media into drive. Identifier should be set to -1, because the
 *	spec does not support any other value.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_device_mount(struct i2o_device *dev, u32 media_id)
{
	struct i2o_message __iomem *msg;
	u32 m;

	m = i2o_msg_get_wait(dev->iop, &msg, I2O_TIMEOUT_MESSAGE_GET);
	if (m == I2O_QUEUE_EMPTY)
		return -ETIMEDOUT;

	writel(FIVE_WORD_MSG_SIZE | SGL_OFFSET_0, &msg->u.head[0]);
	writel(I2O_CMD_BLOCK_MMOUNT << 24 | HOST_TID << 12 | dev->lct_data.tid,
	       &msg->u.head[1]);
	writel(-1, &msg->body[0]);
	writel(0, &msg->body[1]);
	osm_debug("Mounting...\n");

	return i2o_msg_post_wait(dev->iop, m, 2);
};

/**
 *	i2o_block_device_lock - Locks the media of device dev
 *	@dev: I2O device which should receive the lock request
 *	@media_id: Media Identifier
 *
 *	Lock media of device dev to prevent removal. The media identifier
 *	should be set to -1, because the spec does not support any other value.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_device_lock(struct i2o_device *dev, u32 media_id)
{
	struct i2o_message __iomem *msg;
	u32 m;

	m = i2o_msg_get_wait(dev->iop, &msg, I2O_TIMEOUT_MESSAGE_GET);
	if (m == I2O_QUEUE_EMPTY)
		return -ETIMEDOUT;

	writel(FIVE_WORD_MSG_SIZE | SGL_OFFSET_0, &msg->u.head[0]);
	writel(I2O_CMD_BLOCK_MLOCK << 24 | HOST_TID << 12 | dev->lct_data.tid,
	       &msg->u.head[1]);
	writel(-1, &msg->body[0]);
	osm_debug("Locking...\n");

	return i2o_msg_post_wait(dev->iop, m, 2);
};

/**
 *	i2o_block_device_unlock - Unlocks the media of device dev
 *	@dev: I2O device which should receive the unlocked request
 *	@media_id: Media Identifier
 *
 *	Unlocks the media in device dev. The media identifier should be set to
 *	-1, because the spec does not support any other value.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_device_unlock(struct i2o_device *dev, u32 media_id)
{
	struct i2o_message __iomem *msg;
	u32 m;

	m = i2o_msg_get_wait(dev->iop, &msg, I2O_TIMEOUT_MESSAGE_GET);
	if (m == I2O_QUEUE_EMPTY)
		return -ETIMEDOUT;

	writel(FIVE_WORD_MSG_SIZE | SGL_OFFSET_0, &msg->u.head[0]);
	writel(I2O_CMD_BLOCK_MUNLOCK << 24 | HOST_TID << 12 | dev->lct_data.tid,
	       &msg->u.head[1]);
	writel(media_id, &msg->body[0]);
	osm_debug("Unlocking...\n");

	return i2o_msg_post_wait(dev->iop, m, 2);
};

/**
 *	i2o_block_device_power - Power management for device dev
 *	@dev: I2O device which should receive the power management request
 *	@operation: Operation which should be send
 *
 *	Send a power management request to the device dev.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_device_power(struct i2o_block_device *dev, u8 op)
{
	struct i2o_device *i2o_dev = dev->i2o_dev;
	struct i2o_controller *c = i2o_dev->iop;
	struct i2o_message __iomem *msg;
	u32 m;
	int rc;

	m = i2o_msg_get_wait(c, &msg, I2O_TIMEOUT_MESSAGE_GET);
	if (m == I2O_QUEUE_EMPTY)
		return -ETIMEDOUT;

	writel(FOUR_WORD_MSG_SIZE | SGL_OFFSET_0, &msg->u.head[0]);
	writel(I2O_CMD_BLOCK_POWER << 24 | HOST_TID << 12 | i2o_dev->lct_data.
	       tid, &msg->u.head[1]);
	writel(op << 24, &msg->body[0]);
	osm_debug("Power...\n");

	rc = i2o_msg_post_wait(c, m, 60);
	if (!rc)
		dev->power = op;

	return rc;
};

/**
 *	i2o_block_request_alloc - Allocate an I2O block request struct
 *
 *	Allocates an I2O block request struct and initialize the list.
 *
 *	Returns a i2o_block_request pointer on success or negative error code
 *	on failure.
 */
static inline struct i2o_block_request *i2o_block_request_alloc(void)
{
	struct i2o_block_request *ireq;

	ireq = mempool_alloc(i2o_blk_req_pool.pool, GFP_ATOMIC);
	if (!ireq)
		return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&ireq->queue);

	return ireq;
};

/**
 *	i2o_block_request_free - Frees a I2O block request
 *	@ireq: I2O block request which should be freed
 *
 *	Fres the allocated memory (give it back to the request mempool).
 */
static inline void i2o_block_request_free(struct i2o_block_request *ireq)
{
	mempool_free(ireq, i2o_blk_req_pool.pool);
};

/**
 *	i2o_block_sglist_alloc - Allocate the SG list and map it
 *	@c: I2O controller to which the request belongs
 *	@ireq: I2O block request
 *
 *	Builds the SG list and map it to be accessable by the controller.
 *
 *	Returns 0 on failure or 1 on success.
 */
static inline int i2o_block_sglist_alloc(struct i2o_controller *c,
					 struct i2o_block_request *ireq,
					 u32 __iomem ** mptr)
{
	int nents;
	enum dma_data_direction direction;

	ireq->dev = &c->pdev->dev;
	nents = blk_rq_map_sg(ireq->req->q, ireq->req, ireq->sg_table);

	if (rq_data_dir(ireq->req) == READ)
		direction = PCI_DMA_FROMDEVICE;
	else
		direction = PCI_DMA_TODEVICE;

	ireq->sg_nents = nents;

	return i2o_dma_map_sg(c, ireq->sg_table, nents, direction, mptr);
};

/**
 *	i2o_block_sglist_free - Frees the SG list
 *	@ireq: I2O block request from which the SG should be freed
 *
 *	Frees the SG list from the I2O block request.
 */
static inline void i2o_block_sglist_free(struct i2o_block_request *ireq)
{
	enum dma_data_direction direction;

	if (rq_data_dir(ireq->req) == READ)
		direction = PCI_DMA_FROMDEVICE;
	else
		direction = PCI_DMA_TODEVICE;

	dma_unmap_sg(ireq->dev, ireq->sg_table, ireq->sg_nents, direction);
};

/**
 *	i2o_block_prep_req_fn - Allocates I2O block device specific struct
 *	@q: request queue for the request
 *	@req: the request to prepare
 *
 *	Allocate the necessary i2o_block_request struct and connect it to
 *	the request. This is needed that we not loose the SG list later on.
 *
 *	Returns BLKPREP_OK on success or BLKPREP_DEFER on failure.
 */
static int i2o_block_prep_req_fn(struct request_queue *q, struct request *req)
{
	struct i2o_block_device *i2o_blk_dev = q->queuedata;
	struct i2o_block_request *ireq;

	if (unlikely(!i2o_blk_dev)) {
		osm_err("block device already removed\n");
		return BLKPREP_KILL;
	}

	/* request is already processed by us, so return */
	if (req->flags & REQ_SPECIAL) {
		osm_debug("REQ_SPECIAL already set!\n");
		req->flags |= REQ_DONTPREP;
		return BLKPREP_OK;
	}

	/* connect the i2o_block_request to the request */
	if (!req->special) {
		ireq = i2o_block_request_alloc();
		if (unlikely(IS_ERR(ireq))) {
			osm_debug("unable to allocate i2o_block_request!\n");
			return BLKPREP_DEFER;
		}

		ireq->i2o_blk_dev = i2o_blk_dev;
		req->special = ireq;
		ireq->req = req;
	} else
		ireq = req->special;

	/* do not come back here */
	req->flags |= REQ_DONTPREP | REQ_SPECIAL;

	return BLKPREP_OK;
};

/**
 *	i2o_block_delayed_request_fn - delayed request queue function
 *	delayed_request: the delayed request with the queue to start
 *
 *	If the request queue is stopped for a disk, and there is no open
 *	request, a new event is created, which calls this function to start
 *	the queue after I2O_BLOCK_REQUEST_TIME. Otherwise the queue will never
 *	be started again.
 */
static void i2o_block_delayed_request_fn(void *delayed_request)
{
	struct i2o_block_delayed_request *dreq = delayed_request;
	struct request_queue *q = dreq->queue;
	unsigned long flags;

	spin_lock_irqsave(q->queue_lock, flags);
	blk_start_queue(q);
	spin_unlock_irqrestore(q->queue_lock, flags);
	kfree(dreq);
};

/**
 *	i2o_block_end_request - Post-processing of completed commands
 *	@req: request which should be completed
 *	@uptodate: 1 for success, 0 for I/O error, < 0 for specific error
 *	@nr_bytes: number of bytes to complete
 *
 *	Mark the request as complete. The lock must not be held when entering.
 *
 */
static void i2o_block_end_request(struct request *req, int uptodate,
				  int nr_bytes)
{
	struct i2o_block_request *ireq = req->special;
	struct i2o_block_device *dev = ireq->i2o_blk_dev;
	request_queue_t *q = req->q;
	unsigned long flags;

	if (end_that_request_chunk(req, uptodate, nr_bytes)) {
		int leftover = (req->hard_nr_sectors << KERNEL_SECTOR_SHIFT);

		if (blk_pc_request(req))
			leftover = req->data_len;

		if (end_io_error(uptodate))
			end_that_request_chunk(req, 0, leftover);
	}

	add_disk_randomness(req->rq_disk);

	spin_lock_irqsave(q->queue_lock, flags);

	end_that_request_last(req);

	if (likely(dev)) {
		dev->open_queue_depth--;
		list_del(&ireq->queue);
	}

	blk_start_queue(q);

	spin_unlock_irqrestore(q->queue_lock, flags);

	i2o_block_sglist_free(ireq);
	i2o_block_request_free(ireq);
};

/**
 *	i2o_block_reply - Block OSM reply handler.
 *	@c: I2O controller from which the message arrives
 *	@m: message id of reply
 *	qmsg: the actuall I2O message reply
 *
 *	This function gets all the message replies.
 *
 */
static int i2o_block_reply(struct i2o_controller *c, u32 m,
			   struct i2o_message *msg)
{
	struct request *req;
	int uptodate = 1;

	req = i2o_cntxt_list_get(c, le32_to_cpu(msg->u.s.tcntxt));
	if (unlikely(!req)) {
		osm_err("NULL reply received!\n");
		return -1;
	}

	/*
	 *      Lets see what is cooking. We stuffed the
	 *      request in the context.
	 */

	if ((le32_to_cpu(msg->body[0]) >> 24) != 0) {
		u32 status = le32_to_cpu(msg->body[0]);
		/*
		 *      Device not ready means two things. One is that the
		 *      the thing went offline (but not a removal media)
		 *
		 *      The second is that you have a SuperTrak 100 and the
		 *      firmware got constipated. Unlike standard i2o card
		 *      setups the supertrak returns an error rather than
		 *      blocking for the timeout in these cases.
		 *
		 *      Don't stick a supertrak100 into cache aggressive modes
		 */

		osm_err("TID %03x error status: 0x%02x, detailed status: "
			"0x%04x\n", (le32_to_cpu(msg->u.head[1]) >> 12 & 0xfff),
			status >> 24, status & 0xffff);

		req->errors++;

		uptodate = 0;
	}

	i2o_block_end_request(req, uptodate, le32_to_cpu(msg->body[1]));

	return 1;
};

static void i2o_block_event(struct i2o_event *evt)
{
	osm_info("event received\n");
	kfree(evt);
};

/*
 *	SCSI-CAM for ioctl geometry mapping
 *	Duplicated with SCSI - this should be moved into somewhere common
 *	perhaps genhd ?
 *
 * LBA -> CHS mapping table taken from:
 *
 * "Incorporating the I2O Architecture into BIOS for Intel Architecture
 *  Platforms"
 *
 * This is an I2O document that is only available to I2O members,
 * not developers.
 *
 * From my understanding, this is how all the I2O cards do this
 *
 * Disk Size      | Sectors | Heads | Cylinders
 * ---------------+---------+-------+-------------------
 * 1 < X <= 528M  | 63      | 16    | X/(63 * 16 * 512)
 * 528M < X <= 1G | 63      | 32    | X/(63 * 32 * 512)
 * 1 < X <528M    | 63      | 16    | X/(63 * 16 * 512)
 * 1 < X <528M    | 63      | 16    | X/(63 * 16 * 512)
 *
 */
#define	BLOCK_SIZE_528M		1081344
#define	BLOCK_SIZE_1G		2097152
#define	BLOCK_SIZE_21G		4403200
#define	BLOCK_SIZE_42G		8806400
#define	BLOCK_SIZE_84G		17612800

static void i2o_block_biosparam(unsigned long capacity, unsigned short *cyls,
				unsigned char *hds, unsigned char *secs)
{
	unsigned long heads, sectors, cylinders;

	sectors = 63L;		/* Maximize sectors per track */
	if (capacity <= BLOCK_SIZE_528M)
		heads = 16;
	else if (capacity <= BLOCK_SIZE_1G)
		heads = 32;
	else if (capacity <= BLOCK_SIZE_21G)
		heads = 64;
	else if (capacity <= BLOCK_SIZE_42G)
		heads = 128;
	else
		heads = 255;

	cylinders = (unsigned long)capacity / (heads * sectors);

	*cyls = (unsigned short)cylinders;	/* Stuff return values */
	*secs = (unsigned char)sectors;
	*hds = (unsigned char)heads;
}

/**
 *	i2o_block_open - Open the block device
 *
 *	Power up the device, mount and lock the media. This function is called,
 *	if the block device is opened for access.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_open(struct inode *inode, struct file *file)
{
	struct i2o_block_device *dev = inode->i_bdev->bd_disk->private_data;

	if (!dev->i2o_dev)
		return -ENODEV;

	if (dev->power > 0x1f)
		i2o_block_device_power(dev, 0x02);

	i2o_block_device_mount(dev->i2o_dev, -1);

	i2o_block_device_lock(dev->i2o_dev, -1);

	osm_debug("Ready.\n");

	return 0;
};

/**
 *	i2o_block_release - Release the I2O block device
 *
 *	Unlock and unmount the media, and power down the device. Gets called if
 *	the block device is closed.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_release(struct inode *inode, struct file *file)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct i2o_block_device *dev = disk->private_data;
	u8 operation;

	/*
	 * This is to deail with the case of an application
	 * opening a device and then the device dissapears while
	 * it's in use, and then the application tries to release
	 * it.  ex: Unmounting a deleted RAID volume at reboot.
	 * If we send messages, it will just cause FAILs since
	 * the TID no longer exists.
	 */
	if (!dev->i2o_dev)
		return 0;

	i2o_block_device_flush(dev->i2o_dev);

	i2o_block_device_unlock(dev->i2o_dev, -1);

	if (dev->flags & (1 << 3 | 1 << 4))	/* Removable */
		operation = 0x21;
	else
		operation = 0x24;

	i2o_block_device_power(dev, operation);

	return 0;
}

/**
 *	i2o_block_ioctl - Issue device specific ioctl calls.
 *	@cmd: ioctl command
 *	@arg: arg
 *
 *	Handles ioctl request for the block device.
 *
 *	Return 0 on success or negative error on failure.
 */
static int i2o_block_ioctl(struct inode *inode, struct file *file,
			   unsigned int cmd, unsigned long arg)
{
	struct gendisk *disk = inode->i_bdev->bd_disk;
	struct i2o_block_device *dev = disk->private_data;
	void __user *argp = (void __user *)arg;

	/* Anyone capable of this syscall can do *real bad* things */

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	switch (cmd) {
	case HDIO_GETGEO:
		{
			struct hd_geometry g;
			i2o_block_biosparam(get_capacity(disk),
					    &g.cylinders, &g.heads, &g.sectors);
			g.start = get_start_sect(inode->i_bdev);
			return copy_to_user(argp, &g, sizeof(g)) ? -EFAULT : 0;
		}

	case BLKI2OGRSTRAT:
		return put_user(dev->rcache, (int __user *)arg);
	case BLKI2OGWSTRAT:
		return put_user(dev->wcache, (int __user *)arg);
	case BLKI2OSRSTRAT:
		if (arg < 0 || arg > CACHE_SMARTFETCH)
			return -EINVAL;
		dev->rcache = arg;
		break;
	case BLKI2OSWSTRAT:
		if (arg != 0
		    && (arg < CACHE_WRITETHROUGH || arg > CACHE_SMARTBACK))
			return -EINVAL;
		dev->wcache = arg;
		break;
	}
	return -ENOTTY;
};

/**
 *	i2o_block_media_changed - Have we seen a media change?
 *	@disk: gendisk which should be verified
 *
 *	Verifies if the media has changed.
 *
 *	Returns 1 if the media was changed or 0 otherwise.
 */
static int i2o_block_media_changed(struct gendisk *disk)
{
	struct i2o_block_device *p = disk->private_data;

	if (p->media_change_flag) {
		p->media_change_flag = 0;
		return 1;
	}
	return 0;
}

/**
 *	i2o_block_transfer - Transfer a request to/from the I2O controller
 *	@req: the request which should be transfered
 *
 *	This function converts the request into a I2O message. The necessary
 *	DMA buffers are allocated and after everything is setup post the message
 *	to the I2O controller. No cleanup is done by this function. It is done
 *	on the interrupt side when the reply arrives.
 *
 *	Return 0 on success or negative error code on failure.
 */
static int i2o_block_transfer(struct request *req)
{
	struct i2o_block_device *dev = req->rq_disk->private_data;
	struct i2o_controller *c;
	int tid = dev->i2o_dev->lct_data.tid;
	struct i2o_message __iomem *msg;
	u32 __iomem *mptr;
	struct i2o_block_request *ireq = req->special;
	u32 m;
	u32 tcntxt;
	u32 sgl_offset = SGL_OFFSET_8;
	u32 ctl_flags = 0x00000000;
	int rc;
	u32 cmd;

	if (unlikely(!dev->i2o_dev)) {
		osm_err("transfer to removed drive\n");
		rc = -ENODEV;
		goto exit;
	}

	c = dev->i2o_dev->iop;

	m = i2o_msg_get(c, &msg);
	if (m == I2O_QUEUE_EMPTY) {
		rc = -EBUSY;
		goto exit;
	}

	tcntxt = i2o_cntxt_list_add(c, req);
	if (!tcntxt) {
		rc = -ENOMEM;
		goto nop_msg;
	}

	writel(i2o_block_driver.context, &msg->u.s.icntxt);
	writel(tcntxt, &msg->u.s.tcntxt);

	mptr = &msg->body[0];

	if (rq_data_dir(req) == READ) {
		cmd = I2O_CMD_BLOCK_READ << 24;

		switch (dev->rcache) {
		case CACHE_PREFETCH:
			ctl_flags = 0x201F0008;
			break;

		case CACHE_SMARTFETCH:
			if (req->nr_sectors > 16)
				ctl_flags = 0x201F0008;
			else
				ctl_flags = 0x001F0000;
			break;

		default:
			break;
		}
	} else {
		cmd = I2O_CMD_BLOCK_WRITE << 24;

		switch (dev->wcache) {
		case CACHE_WRITETHROUGH:
			ctl_flags = 0x001F0008;
			break;
		case CACHE_WRITEBACK:
			ctl_flags = 0x001F0010;
			break;
		case CACHE_SMARTBACK:
			if (req->nr_sectors > 16)
				ctl_flags = 0x001F0004;
			else
				ctl_flags = 0x001F0010;
			break;
		case CACHE_SMARTTHROUGH:
			if (req->nr_sectors > 16)
				ctl_flags = 0x001F0004;
			else
				ctl_flags = 0x001F0010;
		default:
			break;
		}
	}

#ifdef CONFIG_I2O_EXT_ADAPTEC
	if (c->adaptec) {
		u8 cmd[10];
		u32 scsi_flags;
		u16 hwsec = queue_hardsect_size(req->q) >> KERNEL_SECTOR_SHIFT;

		memset(cmd, 0, 10);

		sgl_offset = SGL_OFFSET_12;

		writel(I2O_CMD_PRIVATE << 24 | HOST_TID << 12 | tid,
		       &msg->u.head[1]);

		writel(I2O_VENDOR_DPT << 16 | I2O_CMD_SCSI_EXEC, mptr++);
		writel(tid, mptr++);

		/*
		 * ENABLE_DISCONNECT
		 * SIMPLE_TAG
		 * RETURN_SENSE_DATA_IN_REPLY_MESSAGE_FRAME
		 */
		if (rq_data_dir(req) == READ) {
			cmd[0] = 0x28;
			scsi_flags = 0x60a0000a;
		} else {
			cmd[0] = 0x2A;
			scsi_flags = 0xa0a0000a;
		}

		writel(scsi_flags, mptr++);

		*((u32 *) & cmd[2]) = cpu_to_be32(req->sector * hwsec);
		*((u16 *) & cmd[7]) = cpu_to_be16(req->nr_sectors * hwsec);

		memcpy_toio(mptr, cmd, 10);
		mptr += 4;
		writel(req->nr_sectors << KERNEL_SECTOR_SHIFT, mptr++);
	} else
#endif
	{
		writel(cmd | HOST_TID << 12 | tid, &msg->u.head[1]);
		writel(ctl_flags, mptr++);
		writel(req->nr_sectors << KERNEL_SECTOR_SHIFT, mptr++);
		writel((u32) (req->sector << KERNEL_SECTOR_SHIFT), mptr++);
		writel(req->sector >> (32 - KERNEL_SECTOR_SHIFT), mptr++);
	}

	if (!i2o_block_sglist_alloc(c, ireq, &mptr)) {
		rc = -ENOMEM;
		goto context_remove;
	}

	writel(I2O_MESSAGE_SIZE(mptr - &msg->u.head[0]) |
	       sgl_offset, &msg->u.head[0]);

	list_add_tail(&ireq->queue, &dev->open_queue);
	dev->open_queue_depth++;

	i2o_msg_post(c, m);

	return 0;

      context_remove:
	i2o_cntxt_list_remove(c, req);

      nop_msg:
	i2o_msg_nop(c, m);

      exit:
	return rc;
};

/**
 *	i2o_block_request_fn - request queue handling function
 *	q: request queue from which the request could be fetched
 *
 *	Takes the next request from the queue, transfers it and if no error
 *	occurs dequeue it from the queue. On arrival of the reply the message
 *	will be processed further. If an error occurs requeue the request.
 */
static void i2o_block_request_fn(struct request_queue *q)
{
	struct request *req;

	while (!blk_queue_plugged(q)) {
		req = elv_next_request(q);
		if (!req)
			break;

		if (blk_fs_request(req)) {
			struct i2o_block_delayed_request *dreq;
			struct i2o_block_request *ireq = req->special;
			unsigned int queue_depth;

			queue_depth = ireq->i2o_blk_dev->open_queue_depth;

			if (queue_depth < I2O_BLOCK_MAX_OPEN_REQUESTS) {
				if (!i2o_block_transfer(req)) {
					blkdev_dequeue_request(req);
					continue;
				} else
					osm_info("transfer error\n");
			}

			if (queue_depth)
				break;

			/* stop the queue and retry later */
			dreq = kmalloc(sizeof(*dreq), GFP_ATOMIC);
			if (!dreq)
				continue;

			dreq->queue = q;
			INIT_WORK(&dreq->work, i2o_block_delayed_request_fn,
				  dreq);

			osm_info("transfer error\n");
			if (!queue_delayed_work(i2o_block_driver.event_queue,
						&dreq->work,
						I2O_BLOCK_RETRY_TIME))
				kfree(dreq);
			else {
				blk_stop_queue(q);
				break;
			}
		} else
			end_request(req, 0);
	}
};

/* I2O Block device operations definition */
static struct block_device_operations i2o_block_fops = {
	.owner = THIS_MODULE,
	.open = i2o_block_open,
	.release = i2o_block_release,
	.ioctl = i2o_block_ioctl,
	.media_changed = i2o_block_media_changed
};

/**
 *	i2o_block_device_alloc - Allocate memory for a I2O Block device
 *
 *	Allocate memory for the i2o_block_device struct, gendisk and request
 *	queue and initialize them as far as no additional information is needed.
 *
 *	Returns a pointer to the allocated I2O Block device on succes or a
 *	negative error code on failure.
 */
static struct i2o_block_device *i2o_block_device_alloc(void)
{
	struct i2o_block_device *dev;
	struct gendisk *gd;
	struct request_queue *queue;
	int rc;

	dev = kmalloc(sizeof(*dev), GFP_KERNEL);
	if (!dev) {
		osm_err("Insufficient memory to allocate I2O Block disk.\n");
		rc = -ENOMEM;
		goto exit;
	}
	memset(dev, 0, sizeof(*dev));

	INIT_LIST_HEAD(&dev->open_queue);
	spin_lock_init(&dev->lock);
	dev->rcache = CACHE_PREFETCH;
	dev->wcache = CACHE_WRITEBACK;

	/* allocate a gendisk with 16 partitions */
	gd = alloc_disk(16);
	if (!gd) {
		osm_err("Insufficient memory to allocate gendisk.\n");
		rc = -ENOMEM;
		goto cleanup_dev;
	}

	/* initialize the request queue */
	queue = blk_init_queue(i2o_block_request_fn, &dev->lock);
	if (!queue) {
		osm_err("Insufficient memory to allocate request queue.\n");
		rc = -ENOMEM;
		goto cleanup_queue;
	}

	blk_queue_prep_rq(queue, i2o_block_prep_req_fn);
	blk_queue_issue_flush_fn(queue, i2o_block_issue_flush);

	gd->major = I2O_MAJOR;
	gd->queue = queue;
	gd->fops = &i2o_block_fops;
	gd->private_data = dev;

	dev->gd = gd;

	return dev;

      cleanup_queue:
	put_disk(gd);

      cleanup_dev:
	kfree(dev);

      exit:
	return ERR_PTR(rc);
};

/**
 *	i2o_block_probe - verify if dev is a I2O Block device and install it
 *	@dev: device to verify if it is a I2O Block device
 *
 *	We only verify if the user_tid of the device is 0xfff and then install
 *	the device. Otherwise it is used by some other device (e. g. RAID).
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int i2o_block_probe(struct device *dev)
{
	struct i2o_device *i2o_dev = to_i2o_device(dev);
	struct i2o_block_device *i2o_blk_dev;
	struct i2o_controller *c = i2o_dev->iop;
	struct gendisk *gd;
	struct request_queue *queue;
	static int unit = 0;
	int rc;
	u64 size;
	u32 blocksize;
	u32 flags, status;
	u16 body_size = 4;
	unsigned short max_sectors;

#ifdef CONFIG_I2O_EXT_ADAPTEC
	if (c->adaptec)
		body_size = 8;
#endif

	if (c->limit_sectors)
		max_sectors = I2O_MAX_SECTORS_LIMITED;
	else
		max_sectors = I2O_MAX_SECTORS;

	/* skip devices which are used by IOP */
	if (i2o_dev->lct_data.user_tid != 0xfff) {
		osm_debug("skipping used device %03x\n", i2o_dev->lct_data.tid);
		return -ENODEV;
	}

	if (i2o_device_claim(i2o_dev)) {
		osm_warn("Unable to claim device. Installation aborted\n");
		rc = -EFAULT;
		goto exit;
	}

	i2o_blk_dev = i2o_block_device_alloc();
	if (IS_ERR(i2o_blk_dev)) {
		osm_err("could not alloc a new I2O block device");
		rc = PTR_ERR(i2o_blk_dev);
		goto claim_release;
	}

	i2o_blk_dev->i2o_dev = i2o_dev;
	dev_set_drvdata(dev, i2o_blk_dev);

	/* setup gendisk */
	gd = i2o_blk_dev->gd;
	gd->first_minor = unit << 4;
	sprintf(gd->disk_name, "i2o/hd%c", 'a' + unit);
	sprintf(gd->devfs_name, "i2o/hd%c", 'a' + unit);
	gd->driverfs_dev = &i2o_dev->device;

	/* setup request queue */
	queue = gd->queue;
	queue->queuedata = i2o_blk_dev;

	blk_queue_max_phys_segments(queue, I2O_MAX_PHYS_SEGMENTS);
	blk_queue_max_sectors(queue, max_sectors);
	blk_queue_max_hw_segments(queue, i2o_sg_tablesize(c, body_size));

	osm_debug("max sectors = %d\n", queue->max_phys_segments);
	osm_debug("phys segments = %d\n", queue->max_sectors);
	osm_debug("max hw segments = %d\n", queue->max_hw_segments);

	/*
	 *      Ask for the current media data. If that isn't supported
	 *      then we ask for the device capacity data
	 */
	if (i2o_parm_field_get(i2o_dev, 0x0004, 1, &blocksize, 4) ||
	    i2o_parm_field_get(i2o_dev, 0x0000, 3, &blocksize, 4)) {
		blk_queue_hardsect_size(queue, blocksize);
	} else
		osm_warn("unable to get blocksize of %s\n", gd->disk_name);

	if (i2o_parm_field_get(i2o_dev, 0x0004, 0, &size, 8) ||
	    i2o_parm_field_get(i2o_dev, 0x0000, 4, &size, 8)) {
		set_capacity(gd, size >> KERNEL_SECTOR_SHIFT);
	} else
		osm_warn("could not get size of %s\n", gd->disk_name);

	if (!i2o_parm_field_get(i2o_dev, 0x0000, 2, &i2o_blk_dev->power, 2))
		i2o_blk_dev->power = 0;
	i2o_parm_field_get(i2o_dev, 0x0000, 5, &flags, 4);
	i2o_parm_field_get(i2o_dev, 0x0000, 6, &status, 4);

	i2o_event_register(i2o_dev, &i2o_block_driver, 0, 0xffffffff);

	add_disk(gd);

	unit++;

	osm_info("device added (TID: %03x): %s\n", i2o_dev->lct_data.tid,
		 i2o_blk_dev->gd->disk_name);

	return 0;

      claim_release:
	i2o_device_claim_release(i2o_dev);

      exit:
	return rc;
};

/* Block OSM driver struct */
static struct i2o_driver i2o_block_driver = {
	.name = OSM_NAME,
	.event = i2o_block_event,
	.reply = i2o_block_reply,
	.classes = i2o_block_class_id,
	.driver = {
		   .probe = i2o_block_probe,
		   .remove = i2o_block_remove,
		   },
};

/**
 *	i2o_block_init - Block OSM initialization function
 *
 *	Allocate the slab and mempool for request structs, registers i2o_block
 *	block device and finally register the Block OSM in the I2O core.
 *
 *	Returns 0 on success or negative error code on failure.
 */
static int __init i2o_block_init(void)
{
	int rc;
	int size;

	printk(KERN_INFO OSM_DESCRIPTION " v" OSM_VERSION "\n");

	/* Allocate request mempool and slab */
	size = sizeof(struct i2o_block_request);
	i2o_blk_req_pool.slab = kmem_cache_create("i2o_block_req", size, 0,
						  SLAB_HWCACHE_ALIGN, NULL,
						  NULL);
	if (!i2o_blk_req_pool.slab) {
		osm_err("can't init request slab\n");
		rc = -ENOMEM;
		goto exit;
	}

	i2o_blk_req_pool.pool = mempool_create(I2O_BLOCK_REQ_MEMPOOL_SIZE,
					       mempool_alloc_slab,
					       mempool_free_slab,
					       i2o_blk_req_pool.slab);
	if (!i2o_blk_req_pool.pool) {
		osm_err("can't init request mempool\n");
		rc = -ENOMEM;
		goto free_slab;
	}

	/* Register the block device interfaces */
	rc = register_blkdev(I2O_MAJOR, "i2o_block");
	if (rc) {
		osm_err("unable to register block device\n");
		goto free_mempool;
	}
#ifdef MODULE
	osm_info("registered device at major %d\n", I2O_MAJOR);
#endif

	/* Register Block OSM into I2O core */
	rc = i2o_driver_register(&i2o_block_driver);
	if (rc) {
		osm_err("Could not register Block driver\n");
		goto unregister_blkdev;
	}

	return 0;

      unregister_blkdev:
	unregister_blkdev(I2O_MAJOR, "i2o_block");

      free_mempool:
	mempool_destroy(i2o_blk_req_pool.pool);

      free_slab:
	kmem_cache_destroy(i2o_blk_req_pool.slab);

      exit:
	return rc;
};

/**
 *	i2o_block_exit - Block OSM exit function
 *
 *	Unregisters Block OSM from I2O core, unregisters i2o_block block device
 *	and frees the mempool and slab.
 */
static void __exit i2o_block_exit(void)
{
	/* Unregister I2O Block OSM from I2O core */
	i2o_driver_unregister(&i2o_block_driver);

	/* Unregister block device */
	unregister_blkdev(I2O_MAJOR, "i2o_block");

	/* Free request mempool and slab */
	mempool_destroy(i2o_blk_req_pool.pool);
	kmem_cache_destroy(i2o_blk_req_pool.slab);
};

MODULE_AUTHOR("Red Hat");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION(OSM_DESCRIPTION);
MODULE_VERSION(OSM_VERSION);

module_init(i2o_block_init);
module_exit(i2o_block_exit);