Merge branch 'master' of /pub/scm/linux/kernel/git/torvalds/linux-2.6

[linux-2.6] / drivers / firewire / fw-sbp2.c

/*
 * SBP2 driver (SCSI over IEEE1394)
 *
 * Copyright (C) 2005-2007  Kristian Hoegsberg <krh@bitplanet.net>
 *
 * 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.
 */

/*
 * The basic structure of this driver is based on the old storage driver,
 * drivers/ieee1394/sbp2.c, originally written by
 *     James Goodwin <jamesg@filanet.com>
 * with later contributions and ongoing maintenance from
 *     Ben Collins <bcollins@debian.org>,
 *     Stefan Richter <stefanr@s5r6.in-berlin.de>
 * and many others.
 */

#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/scatterlist.h>
#include <linux/string.h>
#include <linux/stringify.h>
#include <linux/timer.h>
#include <linux/workqueue.h>
#include <asm/system.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>

#include "fw-device.h"
#include "fw-topology.h"
#include "fw-transaction.h"

/*
 * So far only bridges from Oxford Semiconductor are known to support
 * concurrent logins. Depending on firmware, four or two concurrent logins
 * are possible on OXFW911 and newer Oxsemi bridges.
 *
 * Concurrent logins are useful together with cluster filesystems.
 */
static int sbp2_param_exclusive_login = 1;
module_param_named(exclusive_login, sbp2_param_exclusive_login, bool, 0644);
MODULE_PARM_DESC(exclusive_login, "Exclusive login to sbp2 device "
                 "(default = Y, use N for concurrent initiators)");

/*
 * Flags for firmware oddities
 *
 * - 128kB max transfer
 *   Limit transfer size. Necessary for some old bridges.
 *
 * - 36 byte inquiry
 *   When scsi_mod probes the device, let the inquiry command look like that
 *   from MS Windows.
 *
 * - skip mode page 8
 *   Suppress sending of mode_sense for mode page 8 if the device pretends to
 *   support the SCSI Primary Block commands instead of Reduced Block Commands.
 *
 * - fix capacity
 *   Tell sd_mod to correct the last sector number reported by read_capacity.
 *   Avoids access beyond actual disk limits on devices with an off-by-one bug.
 *   Don't use this with devices which don't have this bug.
 *
 * - delay inquiry
 *   Wait extra SBP2_INQUIRY_DELAY seconds after login before SCSI inquiry.
 *
 * - override internal blacklist
 *   Instead of adding to the built-in blacklist, use only the workarounds
 *   specified in the module load parameter.
 *   Useful if a blacklist entry interfered with a non-broken device.
 */
#define SBP2_WORKAROUND_128K_MAX_TRANS  0x1
#define SBP2_WORKAROUND_INQUIRY_36      0x2
#define SBP2_WORKAROUND_MODE_SENSE_8    0x4
#define SBP2_WORKAROUND_FIX_CAPACITY    0x8
#define SBP2_WORKAROUND_DELAY_INQUIRY   0x10
#define SBP2_INQUIRY_DELAY              12
#define SBP2_WORKAROUND_OVERRIDE        0x100

static int sbp2_param_workarounds;
module_param_named(workarounds, sbp2_param_workarounds, int, 0644);
MODULE_PARM_DESC(workarounds, "Work around device bugs (default = 0"
        ", 128kB max transfer = " __stringify(SBP2_WORKAROUND_128K_MAX_TRANS)
        ", 36 byte inquiry = "    __stringify(SBP2_WORKAROUND_INQUIRY_36)
        ", skip mode page 8 = "   __stringify(SBP2_WORKAROUND_MODE_SENSE_8)
        ", fix capacity = "       __stringify(SBP2_WORKAROUND_FIX_CAPACITY)
        ", delay inquiry = "      __stringify(SBP2_WORKAROUND_DELAY_INQUIRY)
        ", override internal blacklist = " __stringify(SBP2_WORKAROUND_OVERRIDE)
        ", or a combination)");

/* I don't know why the SCSI stack doesn't define something like this... */
typedef void (*scsi_done_fn_t)(struct scsi_cmnd *);

static const char sbp2_driver_name[] = "sbp2";

/*
 * We create one struct sbp2_logical_unit per SBP-2 Logical Unit Number Entry
 * and one struct scsi_device per sbp2_logical_unit.
 */
struct sbp2_logical_unit {
        struct sbp2_target *tgt;
        struct list_head link;
        struct fw_address_handler address_handler;
        struct list_head orb_list;

        u64 command_block_agent_address;
        u16 lun;
        int login_id;

        /*
         * The generation is updated once we've logged in or reconnected
         * to the logical unit.  Thus, I/O to the device will automatically
         * fail and get retried if it happens in a window where the device
         * is not ready, e.g. after a bus reset but before we reconnect.
         */
        int generation;
        int retries;
        struct delayed_work work;
        bool has_sdev;
        bool blocked;
};

/*
 * We create one struct sbp2_target per IEEE 1212 Unit Directory
 * and one struct Scsi_Host per sbp2_target.
 */
struct sbp2_target {
        struct kref kref;
        struct fw_unit *unit;
        const char *bus_id;
        struct list_head lu_list;

        u64 management_agent_address;
        u64 guid;
        int directory_id;
        int node_id;
        int address_high;
        unsigned int workarounds;
        unsigned int mgt_orb_timeout;

        int dont_block; /* counter for each logical unit */
        int blocked;    /* ditto */
};

/*
 * Per section 7.4.8 of the SBP-2 spec, a mgt_ORB_timeout value can be
 * provided in the config rom. Most devices do provide a value, which
 * we'll use for login management orbs, but with some sane limits.
 */
#define SBP2_MIN_LOGIN_ORB_TIMEOUT      5000U   /* Timeout in ms */
#define SBP2_MAX_LOGIN_ORB_TIMEOUT      40000U  /* Timeout in ms */
#define SBP2_ORB_TIMEOUT                2000U   /* Timeout in ms */
#define SBP2_ORB_NULL                   0x80000000
#define SBP2_MAX_SG_ELEMENT_LENGTH      0xf000
#define SBP2_RETRY_LIMIT                0xf             /* 15 retries */
#define SBP2_CYCLE_LIMIT                (0xc8 << 12)    /* 200 125us cycles */

/* Unit directory keys */
#define SBP2_CSR_UNIT_CHARACTERISTICS   0x3a
#define SBP2_CSR_FIRMWARE_REVISION      0x3c
#define SBP2_CSR_LOGICAL_UNIT_NUMBER    0x14
#define SBP2_CSR_LOGICAL_UNIT_DIRECTORY 0xd4

/* Management orb opcodes */
#define SBP2_LOGIN_REQUEST              0x0
#define SBP2_QUERY_LOGINS_REQUEST       0x1
#define SBP2_RECONNECT_REQUEST          0x3
#define SBP2_SET_PASSWORD_REQUEST       0x4
#define SBP2_LOGOUT_REQUEST             0x7
#define SBP2_ABORT_TASK_REQUEST         0xb
#define SBP2_ABORT_TASK_SET             0xc
#define SBP2_LOGICAL_UNIT_RESET         0xe
#define SBP2_TARGET_RESET_REQUEST       0xf

/* Offsets for command block agent registers */
#define SBP2_AGENT_STATE                0x00
#define SBP2_AGENT_RESET                0x04
#define SBP2_ORB_POINTER                0x08
#define SBP2_DOORBELL                   0x10
#define SBP2_UNSOLICITED_STATUS_ENABLE  0x14

/* Status write response codes */
#define SBP2_STATUS_REQUEST_COMPLETE    0x0
#define SBP2_STATUS_TRANSPORT_FAILURE   0x1
#define SBP2_STATUS_ILLEGAL_REQUEST     0x2
#define SBP2_STATUS_VENDOR_DEPENDENT    0x3

#define STATUS_GET_ORB_HIGH(v)          ((v).status & 0xffff)
#define STATUS_GET_SBP_STATUS(v)        (((v).status >> 16) & 0xff)
#define STATUS_GET_LEN(v)               (((v).status >> 24) & 0x07)
#define STATUS_GET_DEAD(v)              (((v).status >> 27) & 0x01)
#define STATUS_GET_RESPONSE(v)          (((v).status >> 28) & 0x03)
#define STATUS_GET_SOURCE(v)            (((v).status >> 30) & 0x03)
#define STATUS_GET_ORB_LOW(v)           ((v).orb_low)
#define STATUS_GET_DATA(v)              ((v).data)

struct sbp2_status {
        u32 status;
        u32 orb_low;
        u8 data[24];
};

struct sbp2_pointer {
        __be32 high;
        __be32 low;
};

struct sbp2_orb {
        struct fw_transaction t;
        struct kref kref;
        dma_addr_t request_bus;
        int rcode;
        struct sbp2_pointer pointer;
        void (*callback)(struct sbp2_orb * orb, struct sbp2_status * status);
        struct list_head link;
};

#define MANAGEMENT_ORB_LUN(v)                   ((v))
#define MANAGEMENT_ORB_FUNCTION(v)              ((v) << 16)
#define MANAGEMENT_ORB_RECONNECT(v)             ((v) << 20)
#define MANAGEMENT_ORB_EXCLUSIVE(v)             ((v) ? 1 << 28 : 0)
#define MANAGEMENT_ORB_REQUEST_FORMAT(v)        ((v) << 29)
#define MANAGEMENT_ORB_NOTIFY                   ((1) << 31)

#define MANAGEMENT_ORB_RESPONSE_LENGTH(v)       ((v))
#define MANAGEMENT_ORB_PASSWORD_LENGTH(v)       ((v) << 16)

struct sbp2_management_orb {
        struct sbp2_orb base;
        struct {
                struct sbp2_pointer password;
                struct sbp2_pointer response;
                __be32 misc;
                __be32 length;
                struct sbp2_pointer status_fifo;
        } request;
        __be32 response[4];
        dma_addr_t response_bus;
        struct completion done;
        struct sbp2_status status;
};

struct sbp2_login_response {
        __be32 misc;
        struct sbp2_pointer command_block_agent;
        __be32 reconnect_hold;
};
#define COMMAND_ORB_DATA_SIZE(v)        ((v))
#define COMMAND_ORB_PAGE_SIZE(v)        ((v) << 16)
#define COMMAND_ORB_PAGE_TABLE_PRESENT  ((1) << 19)
#define COMMAND_ORB_MAX_PAYLOAD(v)      ((v) << 20)
#define COMMAND_ORB_SPEED(v)            ((v) << 24)
#define COMMAND_ORB_DIRECTION           ((1) << 27)
#define COMMAND_ORB_REQUEST_FORMAT(v)   ((v) << 29)
#define COMMAND_ORB_NOTIFY              ((1) << 31)

struct sbp2_command_orb {
        struct sbp2_orb base;
        struct {
                struct sbp2_pointer next;
                struct sbp2_pointer data_descriptor;
                __be32 misc;
                u8 command_block[12];
        } request;
        struct scsi_cmnd *cmd;
        scsi_done_fn_t done;
        struct sbp2_logical_unit *lu;

        struct sbp2_pointer page_table[SG_ALL] __attribute__((aligned(8)));
        dma_addr_t page_table_bus;
};

/*
 * List of devices with known bugs.
 *
 * The firmware_revision field, masked with 0xffff00, is the best
 * indicator for the type of bridge chip of a device.  It yields a few
 * false positives but this did not break correctly behaving devices
 * so far.  We use ~0 as a wildcard, since the 24 bit values we get
 * from the config rom can never match that.
 */
static const struct {
        u32 firmware_revision;
        u32 model;
        unsigned int workarounds;
} sbp2_workarounds_table[] = {
        /* DViCO Momobay CX-1 with TSB42AA9 bridge */ {
                .firmware_revision      = 0x002800,
                .model                  = 0x001010,
                .workarounds            = SBP2_WORKAROUND_INQUIRY_36 |
                                          SBP2_WORKAROUND_MODE_SENSE_8,
        },
        /* DViCO Momobay FX-3A with TSB42AA9A bridge */ {
                .firmware_revision      = 0x002800,
                .model                  = 0x000000,
                .workarounds            = SBP2_WORKAROUND_DELAY_INQUIRY,
        },
        /* Initio bridges, actually only needed for some older ones */ {
                .firmware_revision      = 0x000200,
                .model                  = ~0,
                .workarounds            = SBP2_WORKAROUND_INQUIRY_36,
        },
        /* Symbios bridge */ {
                .firmware_revision      = 0xa0b800,
                .model                  = ~0,
                .workarounds            = SBP2_WORKAROUND_128K_MAX_TRANS,
        },
        /* Datafab MD2-FW2 with Symbios/LSILogic SYM13FW500 bridge */ {
                .firmware_revision      = 0x002600,
                .model                  = ~0,
                .workarounds            = SBP2_WORKAROUND_128K_MAX_TRANS,
        },

        /*
         * There are iPods (2nd gen, 3rd gen) with model_id == 0, but
         * these iPods do not feature the read_capacity bug according
         * to one report.  Read_capacity behaviour as well as model_id
         * could change due to Apple-supplied firmware updates though.
         */

        /* iPod 4th generation. */ {
                .firmware_revision      = 0x0a2700,
                .model                  = 0x000021,
                .workarounds            = SBP2_WORKAROUND_FIX_CAPACITY,
        },
        /* iPod mini */ {
                .firmware_revision      = 0x0a2700,
                .model                  = 0x000023,
                .workarounds            = SBP2_WORKAROUND_FIX_CAPACITY,
        },
        /* iPod Photo */ {
                .firmware_revision      = 0x0a2700,
                .model                  = 0x00007e,
                .workarounds            = SBP2_WORKAROUND_FIX_CAPACITY,
        }
};

static void
free_orb(struct kref *kref)
{
        struct sbp2_orb *orb = container_of(kref, struct sbp2_orb, kref);

        kfree(orb);
}

static void
sbp2_status_write(struct fw_card *card, struct fw_request *request,
                  int tcode, int destination, int source,
                  int generation, int speed,
                  unsigned long long offset,
                  void *payload, size_t length, void *callback_data)
{
        struct sbp2_logical_unit *lu = callback_data;
        struct sbp2_orb *orb;
        struct sbp2_status status;
        size_t header_size;
        unsigned long flags;

        if (tcode != TCODE_WRITE_BLOCK_REQUEST ||
            length == 0 || length > sizeof(status)) {
                fw_send_response(card, request, RCODE_TYPE_ERROR);
                return;
        }

        header_size = min(length, 2 * sizeof(u32));
        fw_memcpy_from_be32(&status, payload, header_size);
        if (length > header_size)
                memcpy(status.data, payload + 8, length - header_size);
        if (STATUS_GET_SOURCE(status) == 2 || STATUS_GET_SOURCE(status) == 3) {
                fw_notify("non-orb related status write, not handled\n");
                fw_send_response(card, request, RCODE_COMPLETE);
                return;
        }

        /* Lookup the orb corresponding to this status write. */
        spin_lock_irqsave(&card->lock, flags);
        list_for_each_entry(orb, &lu->orb_list, link) {
                if (STATUS_GET_ORB_HIGH(status) == 0 &&
                    STATUS_GET_ORB_LOW(status) == orb->request_bus) {
                        orb->rcode = RCODE_COMPLETE;
                        list_del(&orb->link);
                        break;
                }
        }
        spin_unlock_irqrestore(&card->lock, flags);

        if (&orb->link != &lu->orb_list)
                orb->callback(orb, &status);
        else
                fw_error("status write for unknown orb\n");

        kref_put(&orb->kref, free_orb);

        fw_send_response(card, request, RCODE_COMPLETE);
}

static void
complete_transaction(struct fw_card *card, int rcode,
                     void *payload, size_t length, void *data)
{
        struct sbp2_orb *orb = data;
        unsigned long flags;

        /*
         * This is a little tricky.  We can get the status write for
         * the orb before we get this callback.  The status write
         * handler above will assume the orb pointer transaction was
         * successful and set the rcode to RCODE_COMPLETE for the orb.
         * So this callback only sets the rcode if it hasn't already
         * been set and only does the cleanup if the transaction
         * failed and we didn't already get a status write.
         */
        spin_lock_irqsave(&card->lock, flags);

        if (orb->rcode == -1)
                orb->rcode = rcode;
        if (orb->rcode != RCODE_COMPLETE) {
                list_del(&orb->link);
                spin_unlock_irqrestore(&card->lock, flags);
                orb->callback(orb, NULL);
        } else {
                spin_unlock_irqrestore(&card->lock, flags);
        }

        kref_put(&orb->kref, free_orb);
}

static void
sbp2_send_orb(struct sbp2_orb *orb, struct sbp2_logical_unit *lu,
              int node_id, int generation, u64 offset)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        unsigned long flags;

        orb->pointer.high = 0;
        orb->pointer.low = cpu_to_be32(orb->request_bus);

        spin_lock_irqsave(&device->card->lock, flags);
        list_add_tail(&orb->link, &lu->orb_list);
        spin_unlock_irqrestore(&device->card->lock, flags);

        /* Take a ref for the orb list and for the transaction callback. */
        kref_get(&orb->kref);
        kref_get(&orb->kref);

        fw_send_request(device->card, &orb->t, TCODE_WRITE_BLOCK_REQUEST,
                        node_id, generation, device->max_speed, offset,
                        &orb->pointer, sizeof(orb->pointer),
                        complete_transaction, orb);
}

static int sbp2_cancel_orbs(struct sbp2_logical_unit *lu)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        struct sbp2_orb *orb, *next;
        struct list_head list;
        unsigned long flags;
        int retval = -ENOENT;

        INIT_LIST_HEAD(&list);
        spin_lock_irqsave(&device->card->lock, flags);
        list_splice_init(&lu->orb_list, &list);
        spin_unlock_irqrestore(&device->card->lock, flags);

        list_for_each_entry_safe(orb, next, &list, link) {
                retval = 0;
                if (fw_cancel_transaction(device->card, &orb->t) == 0)
                        continue;

                orb->rcode = RCODE_CANCELLED;
                orb->callback(orb, NULL);
        }

        return retval;
}

static void
complete_management_orb(struct sbp2_orb *base_orb, struct sbp2_status *status)
{
        struct sbp2_management_orb *orb =
                container_of(base_orb, struct sbp2_management_orb, base);

        if (status)
                memcpy(&orb->status, status, sizeof(*status));
        complete(&orb->done);
}

static int
sbp2_send_management_orb(struct sbp2_logical_unit *lu, int node_id,
                         int generation, int function, int lun_or_login_id,
                         void *response)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        struct sbp2_management_orb *orb;
        unsigned int timeout;
        int retval = -ENOMEM;

        if (function == SBP2_LOGOUT_REQUEST && fw_device_is_shutdown(device))
                return 0;

        orb = kzalloc(sizeof(*orb), GFP_ATOMIC);
        if (orb == NULL)
                return -ENOMEM;

        kref_init(&orb->base.kref);
        orb->response_bus =
                dma_map_single(device->card->device, &orb->response,
                               sizeof(orb->response), DMA_FROM_DEVICE);
        if (dma_mapping_error(orb->response_bus))
                goto fail_mapping_response;

        orb->request.response.high = 0;
        orb->request.response.low  = cpu_to_be32(orb->response_bus);

        orb->request.misc = cpu_to_be32(
                MANAGEMENT_ORB_NOTIFY |
                MANAGEMENT_ORB_FUNCTION(function) |
                MANAGEMENT_ORB_LUN(lun_or_login_id));
        orb->request.length = cpu_to_be32(
                MANAGEMENT_ORB_RESPONSE_LENGTH(sizeof(orb->response)));

        orb->request.status_fifo.high =
                cpu_to_be32(lu->address_handler.offset >> 32);
        orb->request.status_fifo.low  =
                cpu_to_be32(lu->address_handler.offset);

        if (function == SBP2_LOGIN_REQUEST) {
                /* Ask for 2^2 == 4 seconds reconnect grace period */
                orb->request.misc |= cpu_to_be32(
                        MANAGEMENT_ORB_RECONNECT(2) |
                        MANAGEMENT_ORB_EXCLUSIVE(sbp2_param_exclusive_login));
                timeout = lu->tgt->mgt_orb_timeout;
        } else {
                timeout = SBP2_ORB_TIMEOUT;
        }

        init_completion(&orb->done);
        orb->base.callback = complete_management_orb;

        orb->base.request_bus =
                dma_map_single(device->card->device, &orb->request,
                               sizeof(orb->request), DMA_TO_DEVICE);
        if (dma_mapping_error(orb->base.request_bus))
                goto fail_mapping_request;

        sbp2_send_orb(&orb->base, lu, node_id, generation,
                      lu->tgt->management_agent_address);

        wait_for_completion_timeout(&orb->done, msecs_to_jiffies(timeout));

        retval = -EIO;
        if (sbp2_cancel_orbs(lu) == 0) {
                fw_error("%s: orb reply timed out, rcode=0x%02x\n",
                         lu->tgt->bus_id, orb->base.rcode);
                goto out;
        }

        if (orb->base.rcode != RCODE_COMPLETE) {
                fw_error("%s: management write failed, rcode 0x%02x\n",
                         lu->tgt->bus_id, orb->base.rcode);
                goto out;
        }

        if (STATUS_GET_RESPONSE(orb->status) != 0 ||
            STATUS_GET_SBP_STATUS(orb->status) != 0) {
                fw_error("%s: error status: %d:%d\n", lu->tgt->bus_id,
                         STATUS_GET_RESPONSE(orb->status),
                         STATUS_GET_SBP_STATUS(orb->status));
                goto out;
        }

        retval = 0;
 out:
        dma_unmap_single(device->card->device, orb->base.request_bus,
                         sizeof(orb->request), DMA_TO_DEVICE);
 fail_mapping_request:
        dma_unmap_single(device->card->device, orb->response_bus,
                         sizeof(orb->response), DMA_FROM_DEVICE);
 fail_mapping_response:
        if (response)
                memcpy(response, orb->response, sizeof(orb->response));
        kref_put(&orb->base.kref, free_orb);

        return retval;
}

static void
complete_agent_reset_write(struct fw_card *card, int rcode,
                           void *payload, size_t length, void *done)
{
        complete(done);
}

static void sbp2_agent_reset(struct sbp2_logical_unit *lu)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        DECLARE_COMPLETION_ONSTACK(done);
        struct fw_transaction t;
        static u32 z;

        fw_send_request(device->card, &t, TCODE_WRITE_QUADLET_REQUEST,
                        lu->tgt->node_id, lu->generation, device->max_speed,
                        lu->command_block_agent_address + SBP2_AGENT_RESET,
                        &z, sizeof(z), complete_agent_reset_write, &done);
        wait_for_completion(&done);
}

static void
complete_agent_reset_write_no_wait(struct fw_card *card, int rcode,
                                   void *payload, size_t length, void *data)
{
        kfree(data);
}

static void sbp2_agent_reset_no_wait(struct sbp2_logical_unit *lu)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        struct fw_transaction *t;
        static u32 z;

        t = kmalloc(sizeof(*t), GFP_ATOMIC);
        if (t == NULL)
                return;

        fw_send_request(device->card, t, TCODE_WRITE_QUADLET_REQUEST,
                        lu->tgt->node_id, lu->generation, device->max_speed,
                        lu->command_block_agent_address + SBP2_AGENT_RESET,
                        &z, sizeof(z), complete_agent_reset_write_no_wait, t);
}

static void sbp2_set_generation(struct sbp2_logical_unit *lu, int generation)
{
        struct fw_card *card = fw_device(lu->tgt->unit->device.parent)->card;
        unsigned long flags;

        /* serialize with comparisons of lu->generation and card->generation */
        spin_lock_irqsave(&card->lock, flags);
        lu->generation = generation;
        spin_unlock_irqrestore(&card->lock, flags);
}

static inline void sbp2_allow_block(struct sbp2_logical_unit *lu)
{
        /*
         * We may access dont_block without taking card->lock here:
         * All callers of sbp2_allow_block() and all callers of sbp2_unblock()
         * are currently serialized against each other.
         * And a wrong result in sbp2_conditionally_block()'s access of
         * dont_block is rather harmless, it simply misses its first chance.
         */
        --lu->tgt->dont_block;
}

/*
 * Blocks lu->tgt if all of the following conditions are met:
 *   - Login, INQUIRY, and high-level SCSI setup of all of the target's
 *     logical units have been finished (indicated by dont_block == 0).
 *   - lu->generation is stale.
 *
 * Note, scsi_block_requests() must be called while holding card->lock,
 * otherwise it might foil sbp2_[conditionally_]unblock()'s attempt to
 * unblock the target.
 */
static void sbp2_conditionally_block(struct sbp2_logical_unit *lu)
{
        struct sbp2_target *tgt = lu->tgt;
        struct fw_card *card = fw_device(tgt->unit->device.parent)->card;
        struct Scsi_Host *shost =
                container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
        unsigned long flags;

        spin_lock_irqsave(&card->lock, flags);
        if (!tgt->dont_block && !lu->blocked &&
            lu->generation != card->generation) {
                lu->blocked = true;
                if (++tgt->blocked == 1)
                        scsi_block_requests(shost);
        }
        spin_unlock_irqrestore(&card->lock, flags);
}

/*
 * Unblocks lu->tgt as soon as all its logical units can be unblocked.
 * Note, it is harmless to run scsi_unblock_requests() outside the
 * card->lock protected section.  On the other hand, running it inside
 * the section might clash with shost->host_lock.
 */
static void sbp2_conditionally_unblock(struct sbp2_logical_unit *lu)
{
        struct sbp2_target *tgt = lu->tgt;
        struct fw_card *card = fw_device(tgt->unit->device.parent)->card;
        struct Scsi_Host *shost =
                container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
        unsigned long flags;
        bool unblock = false;

        spin_lock_irqsave(&card->lock, flags);
        if (lu->blocked && lu->generation == card->generation) {
                lu->blocked = false;
                unblock = --tgt->blocked == 0;
        }
        spin_unlock_irqrestore(&card->lock, flags);

        if (unblock)
                scsi_unblock_requests(shost);
}

/*
 * Prevents future blocking of tgt and unblocks it.
 * Note, it is harmless to run scsi_unblock_requests() outside the
 * card->lock protected section.  On the other hand, running it inside
 * the section might clash with shost->host_lock.
 */
static void sbp2_unblock(struct sbp2_target *tgt)
{
        struct fw_card *card = fw_device(tgt->unit->device.parent)->card;
        struct Scsi_Host *shost =
                container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
        unsigned long flags;

        spin_lock_irqsave(&card->lock, flags);
        ++tgt->dont_block;
        spin_unlock_irqrestore(&card->lock, flags);

        scsi_unblock_requests(shost);
}

static int sbp2_lun2int(u16 lun)
{
        struct scsi_lun eight_bytes_lun;

        memset(&eight_bytes_lun, 0, sizeof(eight_bytes_lun));
        eight_bytes_lun.scsi_lun[0] = (lun >> 8) & 0xff;
        eight_bytes_lun.scsi_lun[1] = lun & 0xff;

        return scsilun_to_int(&eight_bytes_lun);
}

static void sbp2_release_target(struct kref *kref)
{
        struct sbp2_target *tgt = container_of(kref, struct sbp2_target, kref);
        struct sbp2_logical_unit *lu, *next;
        struct Scsi_Host *shost =
                container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
        struct scsi_device *sdev;
        struct fw_device *device = fw_device(tgt->unit->device.parent);

        /* prevent deadlocks */
        sbp2_unblock(tgt);

        list_for_each_entry_safe(lu, next, &tgt->lu_list, link) {
                sdev = scsi_device_lookup(shost, 0, 0, sbp2_lun2int(lu->lun));
                if (sdev) {
                        scsi_remove_device(sdev);
                        scsi_device_put(sdev);
                }
                sbp2_send_management_orb(lu, tgt->node_id, lu->generation,
                                SBP2_LOGOUT_REQUEST, lu->login_id, NULL);

                fw_core_remove_address_handler(&lu->address_handler);
                list_del(&lu->link);
                kfree(lu);
        }
        scsi_remove_host(shost);
        fw_notify("released %s\n", tgt->bus_id);

        fw_unit_put(tgt->unit);
        scsi_host_put(shost);
        fw_device_put(device);
}

static struct workqueue_struct *sbp2_wq;

/*
 * Always get the target's kref when scheduling work on one its units.
 * Each workqueue job is responsible to call sbp2_target_put() upon return.
 */
static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
{
        if (queue_delayed_work(sbp2_wq, &lu->work, delay))
                kref_get(&lu->tgt->kref);
}

static void sbp2_target_put(struct sbp2_target *tgt)
{
        kref_put(&tgt->kref, sbp2_release_target);
}

static void
complete_set_busy_timeout(struct fw_card *card, int rcode,
                          void *payload, size_t length, void *done)
{
        complete(done);
}

/*
 * Write retransmit retry values into the BUSY_TIMEOUT register.
 * - The single-phase retry protocol is supported by all SBP-2 devices, but the
 *   default retry_limit value is 0 (i.e. never retry transmission). We write a
 *   saner value after logging into the device.
 * - The dual-phase retry protocol is optional to implement, and if not
 *   supported, writes to the dual-phase portion of the register will be
 *   ignored. We try to write the original 1394-1995 default here.
 * - In the case of devices that are also SBP-3-compliant, all writes are
 *   ignored, as the register is read-only, but contains single-phase retry of
 *   15, which is what we're trying to set for all SBP-2 device anyway, so this
 *   write attempt is safe and yields more consistent behavior for all devices.
 *
 * See section 8.3.2.3.5 of the 1394-1995 spec, section 6.2 of the SBP-2 spec,
 * and section 6.4 of the SBP-3 spec for further details.
 */
static void sbp2_set_busy_timeout(struct sbp2_logical_unit *lu)
{
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        DECLARE_COMPLETION_ONSTACK(done);
        struct fw_transaction t;
        static __be32 busy_timeout;

        busy_timeout = cpu_to_be32(SBP2_CYCLE_LIMIT | SBP2_RETRY_LIMIT);

        fw_send_request(device->card, &t, TCODE_WRITE_QUADLET_REQUEST,
                        lu->tgt->node_id, lu->generation, device->max_speed,
                        CSR_REGISTER_BASE + CSR_BUSY_TIMEOUT, &busy_timeout,
                        sizeof(busy_timeout), complete_set_busy_timeout, &done);
        wait_for_completion(&done);
}

static void sbp2_reconnect(struct work_struct *work);

static void sbp2_login(struct work_struct *work)
{
        struct sbp2_logical_unit *lu =
                container_of(work, struct sbp2_logical_unit, work.work);
        struct sbp2_target *tgt = lu->tgt;
        struct fw_device *device = fw_device(tgt->unit->device.parent);
        struct Scsi_Host *shost;
        struct scsi_device *sdev;
        struct sbp2_login_response response;
        int generation, node_id, local_node_id;

        if (fw_device_is_shutdown(device))
                goto out;

        generation    = device->generation;
        smp_rmb();    /* node_id must not be older than generation */
        node_id       = device->node_id;
        local_node_id = device->card->node_id;

        /* If this is a re-login attempt, log out, or we might be rejected. */
        if (lu->has_sdev)
                sbp2_send_management_orb(lu, device->node_id, generation,
                                SBP2_LOGOUT_REQUEST, lu->login_id, NULL);

        if (sbp2_send_management_orb(lu, node_id, generation,
                                SBP2_LOGIN_REQUEST, lu->lun, &response) < 0) {
                if (lu->retries++ < 5) {
                        sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
                } else {
                        fw_error("%s: failed to login to LUN %04x\n",
                                 tgt->bus_id, lu->lun);
                        /* Let any waiting I/O fail from now on. */
                        sbp2_unblock(lu->tgt);
                }
                goto out;
        }

        tgt->node_id      = node_id;
        tgt->address_high = local_node_id << 16;
        sbp2_set_generation(lu, generation);

        lu->command_block_agent_address =
                ((u64)(be32_to_cpu(response.command_block_agent.high) & 0xffff)
                      << 32) | be32_to_cpu(response.command_block_agent.low);
        lu->login_id = be32_to_cpu(response.misc) & 0xffff;

        fw_notify("%s: logged in to LUN %04x (%d retries)\n",
                  tgt->bus_id, lu->lun, lu->retries);

        /* set appropriate retry limit(s) in BUSY_TIMEOUT register */
        sbp2_set_busy_timeout(lu);

        PREPARE_DELAYED_WORK(&lu->work, sbp2_reconnect);
        sbp2_agent_reset(lu);

        /* This was a re-login. */
        if (lu->has_sdev) {
                sbp2_cancel_orbs(lu);
                sbp2_conditionally_unblock(lu);
                goto out;
        }

        if (lu->tgt->workarounds & SBP2_WORKAROUND_DELAY_INQUIRY)
                ssleep(SBP2_INQUIRY_DELAY);

        shost = container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
        sdev = __scsi_add_device(shost, 0, 0, sbp2_lun2int(lu->lun), lu);
        /*
         * FIXME:  We are unable to perform reconnects while in sbp2_login().
         * Therefore __scsi_add_device() will get into trouble if a bus reset
         * happens in parallel.  It will either fail or leave us with an
         * unusable sdev.  As a workaround we check for this and retry the
         * whole login and SCSI probing.
         */

        /* Reported error during __scsi_add_device() */
        if (IS_ERR(sdev))
                goto out_logout_login;

        /* Unreported error during __scsi_add_device() */
        smp_rmb(); /* get current card generation */
        if (generation != device->card->generation) {
                scsi_remove_device(sdev);
                scsi_device_put(sdev);
                goto out_logout_login;
        }

        /* No error during __scsi_add_device() */
        lu->has_sdev = true;
        scsi_device_put(sdev);
        sbp2_allow_block(lu);
        goto out;

 out_logout_login:
        smp_rmb(); /* generation may have changed */
        generation = device->generation;
        smp_rmb(); /* node_id must not be older than generation */

        sbp2_send_management_orb(lu, device->node_id, generation,
                                 SBP2_LOGOUT_REQUEST, lu->login_id, NULL);
        /*
         * If a bus reset happened, sbp2_update will have requeued
         * lu->work already.  Reset the work from reconnect to login.
         */
        PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
 out:
        sbp2_target_put(tgt);
}

static int sbp2_add_logical_unit(struct sbp2_target *tgt, int lun_entry)
{
        struct sbp2_logical_unit *lu;

        lu = kmalloc(sizeof(*lu), GFP_KERNEL);
        if (!lu)
                return -ENOMEM;

        lu->address_handler.length           = 0x100;
        lu->address_handler.address_callback = sbp2_status_write;
        lu->address_handler.callback_data    = lu;

        if (fw_core_add_address_handler(&lu->address_handler,
                                        &fw_high_memory_region) < 0) {
                kfree(lu);
                return -ENOMEM;
        }

        lu->tgt      = tgt;
        lu->lun      = lun_entry & 0xffff;
        lu->retries  = 0;
        lu->has_sdev = false;
        lu->blocked  = false;
        ++tgt->dont_block;
        INIT_LIST_HEAD(&lu->orb_list);
        INIT_DELAYED_WORK(&lu->work, sbp2_login);

        list_add_tail(&lu->link, &tgt->lu_list);
        return 0;
}

static int sbp2_scan_logical_unit_dir(struct sbp2_target *tgt, u32 *directory)
{
        struct fw_csr_iterator ci;
        int key, value;

        fw_csr_iterator_init(&ci, directory);
        while (fw_csr_iterator_next(&ci, &key, &value))
                if (key == SBP2_CSR_LOGICAL_UNIT_NUMBER &&
                    sbp2_add_logical_unit(tgt, value) < 0)
                        return -ENOMEM;
        return 0;
}

static int sbp2_scan_unit_dir(struct sbp2_target *tgt, u32 *directory,
                              u32 *model, u32 *firmware_revision)
{
        struct fw_csr_iterator ci;
        int key, value;
        unsigned int timeout;

        fw_csr_iterator_init(&ci, directory);
        while (fw_csr_iterator_next(&ci, &key, &value)) {
                switch (key) {

                case CSR_DEPENDENT_INFO | CSR_OFFSET:
                        tgt->management_agent_address =
                                        CSR_REGISTER_BASE + 4 * value;
                        break;

                case CSR_DIRECTORY_ID:
                        tgt->directory_id = value;
                        break;

                case CSR_MODEL:
                        *model = value;
                        break;

                case SBP2_CSR_FIRMWARE_REVISION:
                        *firmware_revision = value;
                        break;

                case SBP2_CSR_UNIT_CHARACTERISTICS:
                        /* the timeout value is stored in 500ms units */
                        timeout = ((unsigned int) value >> 8 & 0xff) * 500;
                        timeout = max(timeout, SBP2_MIN_LOGIN_ORB_TIMEOUT);
                        tgt->mgt_orb_timeout =
                                  min(timeout, SBP2_MAX_LOGIN_ORB_TIMEOUT);

                        if (timeout > tgt->mgt_orb_timeout)
                                fw_notify("%s: config rom contains %ds "
                                          "management ORB timeout, limiting "
                                          "to %ds\n", tgt->bus_id,
                                          timeout / 1000,
                                          tgt->mgt_orb_timeout / 1000);
                        break;

                case SBP2_CSR_LOGICAL_UNIT_NUMBER:
                        if (sbp2_add_logical_unit(tgt, value) < 0)
                                return -ENOMEM;
                        break;

                case SBP2_CSR_LOGICAL_UNIT_DIRECTORY:
                        if (sbp2_scan_logical_unit_dir(tgt, ci.p + value) < 0)
                                return -ENOMEM;
                        break;
                }
        }
        return 0;
}

static void sbp2_init_workarounds(struct sbp2_target *tgt, u32 model,
                                  u32 firmware_revision)
{
        int i;
        unsigned int w = sbp2_param_workarounds;

        if (w)
                fw_notify("Please notify linux1394-devel@lists.sourceforge.net "
                          "if you need the workarounds parameter for %s\n",
                          tgt->bus_id);

        if (w & SBP2_WORKAROUND_OVERRIDE)
                goto out;

        for (i = 0; i < ARRAY_SIZE(sbp2_workarounds_table); i++) {

                if (sbp2_workarounds_table[i].firmware_revision !=
                    (firmware_revision & 0xffffff00))
                        continue;

                if (sbp2_workarounds_table[i].model != model &&
                    sbp2_workarounds_table[i].model != ~0)
                        continue;

                w |= sbp2_workarounds_table[i].workarounds;
                break;
        }
 out:
        if (w)
                fw_notify("Workarounds for %s: 0x%x "
                          "(firmware_revision 0x%06x, model_id 0x%06x)\n",
                          tgt->bus_id, w, firmware_revision, model);
        tgt->workarounds = w;
}

static struct scsi_host_template scsi_driver_template;

static int sbp2_probe(struct device *dev)
{
        struct fw_unit *unit = fw_unit(dev);
        struct fw_device *device = fw_device(unit->device.parent);
        struct sbp2_target *tgt;
        struct sbp2_logical_unit *lu;
        struct Scsi_Host *shost;
        u32 model, firmware_revision;

        shost = scsi_host_alloc(&scsi_driver_template, sizeof(*tgt));
        if (shost == NULL)
                return -ENOMEM;

        tgt = (struct sbp2_target *)shost->hostdata;
        unit->device.driver_data = tgt;
        tgt->unit = unit;
        kref_init(&tgt->kref);
        INIT_LIST_HEAD(&tgt->lu_list);
        tgt->bus_id = unit->device.bus_id;
        tgt->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];

        if (fw_device_enable_phys_dma(device) < 0)
                goto fail_shost_put;

        if (scsi_add_host(shost, &unit->device) < 0)
                goto fail_shost_put;

        fw_device_get(device);
        fw_unit_get(unit);

        /* Initialize to values that won't match anything in our table. */
        firmware_revision = 0xff000000;
        model = 0xff000000;

        /* implicit directory ID */
        tgt->directory_id = ((unit->directory - device->config_rom) * 4
                             + CSR_CONFIG_ROM) & 0xffffff;

        if (sbp2_scan_unit_dir(tgt, unit->directory, &model,
                               &firmware_revision) < 0)
                goto fail_tgt_put;

        sbp2_init_workarounds(tgt, model, firmware_revision);

        /* Do the login in a workqueue so we can easily reschedule retries. */
        list_for_each_entry(lu, &tgt->lu_list, link)
                sbp2_queue_work(lu, 0);
        return 0;

 fail_tgt_put:
        sbp2_target_put(tgt);
        return -ENOMEM;

 fail_shost_put:
        scsi_host_put(shost);
        return -ENOMEM;
}

static int sbp2_remove(struct device *dev)
{
        struct fw_unit *unit = fw_unit(dev);
        struct sbp2_target *tgt = unit->device.driver_data;

        sbp2_target_put(tgt);
        return 0;
}

static void sbp2_reconnect(struct work_struct *work)
{
        struct sbp2_logical_unit *lu =
                container_of(work, struct sbp2_logical_unit, work.work);
        struct sbp2_target *tgt = lu->tgt;
        struct fw_device *device = fw_device(tgt->unit->device.parent);
        int generation, node_id, local_node_id;

        if (fw_device_is_shutdown(device))
                goto out;

        generation    = device->generation;
        smp_rmb();    /* node_id must not be older than generation */
        node_id       = device->node_id;
        local_node_id = device->card->node_id;

        if (sbp2_send_management_orb(lu, node_id, generation,
                                     SBP2_RECONNECT_REQUEST,
                                     lu->login_id, NULL) < 0) {
                /*
                 * If reconnect was impossible even though we are in the
                 * current generation, fall back and try to log in again.
                 *
                 * We could check for "Function rejected" status, but
                 * looking at the bus generation as simpler and more general.
                 */
                smp_rmb(); /* get current card generation */
                if (generation == device->card->generation ||
                    lu->retries++ >= 5) {
                        fw_error("%s: failed to reconnect\n", tgt->bus_id);
                        lu->retries = 0;
                        PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
                }
                sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));
                goto out;
        }

        tgt->node_id      = node_id;
        tgt->address_high = local_node_id << 16;
        sbp2_set_generation(lu, generation);

        fw_notify("%s: reconnected to LUN %04x (%d retries)\n",
                  tgt->bus_id, lu->lun, lu->retries);

        sbp2_agent_reset(lu);
        sbp2_cancel_orbs(lu);
        sbp2_conditionally_unblock(lu);
 out:
        sbp2_target_put(tgt);
}

static void sbp2_update(struct fw_unit *unit)
{
        struct sbp2_target *tgt = unit->device.driver_data;
        struct sbp2_logical_unit *lu;

        fw_device_enable_phys_dma(fw_device(unit->device.parent));

        /*
         * Fw-core serializes sbp2_update() against sbp2_remove().
         * Iteration over tgt->lu_list is therefore safe here.
         */
        list_for_each_entry(lu, &tgt->lu_list, link) {
                sbp2_conditionally_block(lu);
                lu->retries = 0;
                sbp2_queue_work(lu, 0);
        }
}

#define SBP2_UNIT_SPEC_ID_ENTRY 0x0000609e
#define SBP2_SW_VERSION_ENTRY   0x00010483

static const struct fw_device_id sbp2_id_table[] = {
        {
                .match_flags  = FW_MATCH_SPECIFIER_ID | FW_MATCH_VERSION,
                .specifier_id = SBP2_UNIT_SPEC_ID_ENTRY,
                .version      = SBP2_SW_VERSION_ENTRY,
        },
        { }
};

static struct fw_driver sbp2_driver = {
        .driver   = {
                .owner  = THIS_MODULE,
                .name   = sbp2_driver_name,
                .bus    = &fw_bus_type,
                .probe  = sbp2_probe,
                .remove = sbp2_remove,
        },
        .update   = sbp2_update,
        .id_table = sbp2_id_table,
};

static unsigned int
sbp2_status_to_sense_data(u8 *sbp2_status, u8 *sense_data)
{
        int sam_status;

        sense_data[0] = 0x70;
        sense_data[1] = 0x0;
        sense_data[2] = sbp2_status[1];
        sense_data[3] = sbp2_status[4];
        sense_data[4] = sbp2_status[5];
        sense_data[5] = sbp2_status[6];
        sense_data[6] = sbp2_status[7];
        sense_data[7] = 10;
        sense_data[8] = sbp2_status[8];
        sense_data[9] = sbp2_status[9];
        sense_data[10] = sbp2_status[10];
        sense_data[11] = sbp2_status[11];
        sense_data[12] = sbp2_status[2];
        sense_data[13] = sbp2_status[3];
        sense_data[14] = sbp2_status[12];
        sense_data[15] = sbp2_status[13];

        sam_status = sbp2_status[0] & 0x3f;

        switch (sam_status) {
        case SAM_STAT_GOOD:
        case SAM_STAT_CHECK_CONDITION:
        case SAM_STAT_CONDITION_MET:
        case SAM_STAT_BUSY:
        case SAM_STAT_RESERVATION_CONFLICT:
        case SAM_STAT_COMMAND_TERMINATED:
                return DID_OK << 16 | sam_status;

        default:
                return DID_ERROR << 16;
        }
}

static void
complete_command_orb(struct sbp2_orb *base_orb, struct sbp2_status *status)
{
        struct sbp2_command_orb *orb =
                container_of(base_orb, struct sbp2_command_orb, base);
        struct fw_device *device = fw_device(orb->lu->tgt->unit->device.parent);
        int result;

        if (status != NULL) {
                if (STATUS_GET_DEAD(*status))
                        sbp2_agent_reset_no_wait(orb->lu);

                switch (STATUS_GET_RESPONSE(*status)) {
                case SBP2_STATUS_REQUEST_COMPLETE:
                        result = DID_OK << 16;
                        break;
                case SBP2_STATUS_TRANSPORT_FAILURE:
                        result = DID_BUS_BUSY << 16;
                        break;
                case SBP2_STATUS_ILLEGAL_REQUEST:
                case SBP2_STATUS_VENDOR_DEPENDENT:
                default:
                        result = DID_ERROR << 16;
                        break;
                }

                if (result == DID_OK << 16 && STATUS_GET_LEN(*status) > 1)
                        result = sbp2_status_to_sense_data(STATUS_GET_DATA(*status),
                                                           orb->cmd->sense_buffer);
        } else {
                /*
                 * If the orb completes with status == NULL, something
                 * went wrong, typically a bus reset happened mid-orb
                 * or when sending the write (less likely).
                 */
                result = DID_BUS_BUSY << 16;
                sbp2_conditionally_block(orb->lu);
        }

        dma_unmap_single(device->card->device, orb->base.request_bus,
                         sizeof(orb->request), DMA_TO_DEVICE);

        if (scsi_sg_count(orb->cmd) > 0)
                dma_unmap_sg(device->card->device, scsi_sglist(orb->cmd),
                             scsi_sg_count(orb->cmd),
                             orb->cmd->sc_data_direction);

        if (orb->page_table_bus != 0)
                dma_unmap_single(device->card->device, orb->page_table_bus,
                                 sizeof(orb->page_table), DMA_TO_DEVICE);

        orb->cmd->result = result;
        orb->done(orb->cmd);
}

static int
sbp2_map_scatterlist(struct sbp2_command_orb *orb, struct fw_device *device,
                     struct sbp2_logical_unit *lu)
{
        struct scatterlist *sg;
        int sg_len, l, i, j, count;
        dma_addr_t sg_addr;

        sg = scsi_sglist(orb->cmd);
        count = dma_map_sg(device->card->device, sg, scsi_sg_count(orb->cmd),
                           orb->cmd->sc_data_direction);
        if (count == 0)
                goto fail;

        /*
         * Handle the special case where there is only one element in
         * the scatter list by converting it to an immediate block
         * request. This is also a workaround for broken devices such
         * as the second generation iPod which doesn't support page
         * tables.
         */
        if (count == 1 && sg_dma_len(sg) < SBP2_MAX_SG_ELEMENT_LENGTH) {
                orb->request.data_descriptor.high =
                        cpu_to_be32(lu->tgt->address_high);
                orb->request.data_descriptor.low  =
                        cpu_to_be32(sg_dma_address(sg));
                orb->request.misc |=
                        cpu_to_be32(COMMAND_ORB_DATA_SIZE(sg_dma_len(sg)));
                return 0;
        }

        /*
         * Convert the scatterlist to an sbp2 page table.  If any
         * scatterlist entries are too big for sbp2, we split them as we
         * go.  Even if we ask the block I/O layer to not give us sg
         * elements larger than 65535 bytes, some IOMMUs may merge sg elements
         * during DMA mapping, and Linux currently doesn't prevent this.
         */
        for (i = 0, j = 0; i < count; i++, sg = sg_next(sg)) {
                sg_len = sg_dma_len(sg);
                sg_addr = sg_dma_address(sg);
                while (sg_len) {
                        /* FIXME: This won't get us out of the pinch. */
                        if (unlikely(j >= ARRAY_SIZE(orb->page_table))) {
                                fw_error("page table overflow\n");
                                goto fail_page_table;
                        }
                        l = min(sg_len, SBP2_MAX_SG_ELEMENT_LENGTH);
                        orb->page_table[j].low = cpu_to_be32(sg_addr);
                        orb->page_table[j].high = cpu_to_be32(l << 16);
                        sg_addr += l;
                        sg_len -= l;
                        j++;
                }
        }

        orb->page_table_bus =
                dma_map_single(device->card->device, orb->page_table,
                               sizeof(orb->page_table), DMA_TO_DEVICE);
        if (dma_mapping_error(orb->page_table_bus))
                goto fail_page_table;

        /*
         * The data_descriptor pointer is the one case where we need
         * to fill in the node ID part of the address.  All other
         * pointers assume that the data referenced reside on the
         * initiator (i.e. us), but data_descriptor can refer to data
         * on other nodes so we need to put our ID in descriptor.high.
         */
        orb->request.data_descriptor.high = cpu_to_be32(lu->tgt->address_high);
        orb->request.data_descriptor.low  = cpu_to_be32(orb->page_table_bus);
        orb->request.misc |= cpu_to_be32(COMMAND_ORB_PAGE_TABLE_PRESENT |
                                         COMMAND_ORB_DATA_SIZE(j));

        return 0;

 fail_page_table:
        dma_unmap_sg(device->card->device, sg, scsi_sg_count(orb->cmd),
                     orb->cmd->sc_data_direction);
 fail:
        return -ENOMEM;
}

/* SCSI stack integration */

static int sbp2_scsi_queuecommand(struct scsi_cmnd *cmd, scsi_done_fn_t done)
{
        struct sbp2_logical_unit *lu = cmd->device->hostdata;
        struct fw_device *device = fw_device(lu->tgt->unit->device.parent);
        struct sbp2_command_orb *orb;
        unsigned int max_payload;
        int retval = SCSI_MLQUEUE_HOST_BUSY;

        /*
         * Bidirectional commands are not yet implemented, and unknown
         * transfer direction not handled.
         */
        if (cmd->sc_data_direction == DMA_BIDIRECTIONAL) {
                fw_error("Can't handle DMA_BIDIRECTIONAL, rejecting command\n");
                cmd->result = DID_ERROR << 16;
                done(cmd);
                return 0;
        }

        orb = kzalloc(sizeof(*orb), GFP_ATOMIC);
        if (orb == NULL) {
                fw_notify("failed to alloc orb\n");
                return SCSI_MLQUEUE_HOST_BUSY;
        }

        /* Initialize rcode to something not RCODE_COMPLETE. */
        orb->base.rcode = -1;
        kref_init(&orb->base.kref);

        orb->lu   = lu;
        orb->done = done;
        orb->cmd  = cmd;

        orb->request.next.high   = cpu_to_be32(SBP2_ORB_NULL);
        /*
         * At speed 100 we can do 512 bytes per packet, at speed 200,
         * 1024 bytes per packet etc.  The SBP-2 max_payload field
         * specifies the max payload size as 2 ^ (max_payload + 2), so
         * if we set this to max_speed + 7, we get the right value.
         */
        max_payload = min(device->max_speed + 7,
                          device->card->max_receive - 1);
        orb->request.misc = cpu_to_be32(
                COMMAND_ORB_MAX_PAYLOAD(max_payload) |
                COMMAND_ORB_SPEED(device->max_speed) |
                COMMAND_ORB_NOTIFY);

        if (cmd->sc_data_direction == DMA_FROM_DEVICE)
                orb->request.misc |= cpu_to_be32(COMMAND_ORB_DIRECTION);

        if (scsi_sg_count(cmd) && sbp2_map_scatterlist(orb, device, lu) < 0)
                goto out;

        memcpy(orb->request.command_block, cmd->cmnd, COMMAND_SIZE(*cmd->cmnd));

        orb->base.callback = complete_command_orb;
        orb->base.request_bus =
                dma_map_single(device->card->device, &orb->request,
                               sizeof(orb->request), DMA_TO_DEVICE);
        if (dma_mapping_error(orb->base.request_bus))
                goto out;

        sbp2_send_orb(&orb->base, lu, lu->tgt->node_id, lu->generation,
                      lu->command_block_agent_address + SBP2_ORB_POINTER);
        retval = 0;
 out:
        kref_put(&orb->base.kref, free_orb);
        return retval;
}

static int sbp2_scsi_slave_alloc(struct scsi_device *sdev)
{
        struct sbp2_logical_unit *lu = sdev->hostdata;

        /* (Re-)Adding logical units via the SCSI stack is not supported. */
        if (!lu)
                return -ENOSYS;

        sdev->allow_restart = 1;

        /* SBP-2 requires quadlet alignment of the data buffers. */
        blk_queue_update_dma_alignment(sdev->request_queue, 4 - 1);

        if (lu->tgt->workarounds & SBP2_WORKAROUND_INQUIRY_36)
                sdev->inquiry_len = 36;

        return 0;
}

static int sbp2_scsi_slave_configure(struct scsi_device *sdev)
{
        struct sbp2_logical_unit *lu = sdev->hostdata;

        sdev->use_10_for_rw = 1;

        if (sdev->type == TYPE_ROM)
                sdev->use_10_for_ms = 1;

        if (sdev->type == TYPE_DISK &&
            lu->tgt->workarounds & SBP2_WORKAROUND_MODE_SENSE_8)
                sdev->skip_ms_page_8 = 1;

        if (lu->tgt->workarounds & SBP2_WORKAROUND_FIX_CAPACITY)
                sdev->fix_capacity = 1;

        if (lu->tgt->workarounds & SBP2_WORKAROUND_128K_MAX_TRANS)
                blk_queue_max_sectors(sdev->request_queue, 128 * 1024 / 512);

        return 0;
}

/*
 * Called by scsi stack when something has really gone wrong.  Usually
 * called when a command has timed-out for some reason.
 */
static int sbp2_scsi_abort(struct scsi_cmnd *cmd)
{
        struct sbp2_logical_unit *lu = cmd->device->hostdata;

        fw_notify("%s: sbp2_scsi_abort\n", lu->tgt->bus_id);
        sbp2_agent_reset(lu);
        sbp2_cancel_orbs(lu);

        return SUCCESS;
}

/*
 * Format of /sys/bus/scsi/devices/.../ieee1394_id:
 * u64 EUI-64 : u24 directory_ID : u16 LUN  (all printed in hexadecimal)
 *
 * This is the concatenation of target port identifier and logical unit
 * identifier as per SAM-2...SAM-4 annex A.
 */
static ssize_t
sbp2_sysfs_ieee1394_id_show(struct device *dev, struct device_attribute *attr,
                            char *buf)
{
        struct scsi_device *sdev = to_scsi_device(dev);
        struct sbp2_logical_unit *lu;

        if (!sdev)
                return 0;

        lu = sdev->hostdata;

        return sprintf(buf, "%016llx:%06x:%04x\n",
                        (unsigned long long)lu->tgt->guid,
                        lu->tgt->directory_id, lu->lun);
}

static DEVICE_ATTR(ieee1394_id, S_IRUGO, sbp2_sysfs_ieee1394_id_show, NULL);

static struct device_attribute *sbp2_scsi_sysfs_attrs[] = {
        &dev_attr_ieee1394_id,
        NULL
};

static struct scsi_host_template scsi_driver_template = {
        .module                 = THIS_MODULE,
        .name                   = "SBP-2 IEEE-1394",
        .proc_name              = sbp2_driver_name,
        .queuecommand           = sbp2_scsi_queuecommand,
        .slave_alloc            = sbp2_scsi_slave_alloc,
        .slave_configure        = sbp2_scsi_slave_configure,
        .eh_abort_handler       = sbp2_scsi_abort,
        .this_id                = -1,
        .sg_tablesize           = SG_ALL,
        .use_clustering         = ENABLE_CLUSTERING,
        .cmd_per_lun            = 1,
        .can_queue              = 1,
        .sdev_attrs             = sbp2_scsi_sysfs_attrs,
};

MODULE_AUTHOR("Kristian Hoegsberg <krh@bitplanet.net>");
MODULE_DESCRIPTION("SCSI over IEEE1394");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(ieee1394, sbp2_id_table);

/* Provide a module alias so root-on-sbp2 initrds don't break. */
#ifndef CONFIG_IEEE1394_SBP2_MODULE
MODULE_ALIAS("sbp2");
#endif

static int __init sbp2_init(void)
{
        sbp2_wq = create_singlethread_workqueue(KBUILD_MODNAME);
        if (!sbp2_wq)
                return -ENOMEM;

        return driver_register(&sbp2_driver.driver);
}

static void __exit sbp2_cleanup(void)
{
        driver_unregister(&sbp2_driver.driver);
        destroy_workqueue(sbp2_wq);
}

module_init(sbp2_init);
module_exit(sbp2_cleanup);