sbp2.c

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/*
 * SBP2 driver (SCSI over IEEE1394)
 *
 * Copyright (C) 2005-2007  Kristian Hoegsberg <[email protected]>
 *
 * 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 <[email protected]>
 * with later contributions and ongoing maintenance from
 *     Ben Collins <[email protected]>,
 *     Stefan Richter <[email protected]>
 * and many others.
 */

#include <linux/blkdev.h>
#include <linux/bug.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/firewire.h>
#include <linux/firewire-constants.h>
#include <linux/init.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/list.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/scatterlist.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/stringify.h>
#include <linux/workqueue.h>

#include <asm/byteorder.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.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 bool 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.
 *
 * - power condition
 *   Set the power condition field in the START STOP UNIT commands sent by
 *   sd_mod on suspend, resume, and shutdown (if manage_start_stop is on).
 *   Some disks need this to spin down or to resume properly.
 *
 * - 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_POWER_CONDITION 0x20
#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)
    ", set power condition in start stop unit = "
                  __stringify(SBP2_WORKAROUND_POWER_CONDITION)
    ", override internal blacklist = " __stringify(SBP2_WORKAROUND_OVERRIDE)
    ", or a combination)");

/*
 * 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;
};

static void sbp2_queue_work(struct sbp2_logical_unit *lu, unsigned long delay)
{
    queue_delayed_work(fw_workqueue, &lu->work, delay);
}

/*
 * We create one struct sbp2_target per IEEE 1212 Unit Directory
 * and one struct Scsi_Host per sbp2_target.
 */
struct sbp2_target {
    struct fw_unit *unit;
    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;
    unsigned int max_payload;

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

static struct fw_device *target_parent_device(struct sbp2_target *tgt)
{
    return fw_parent_device(tgt->unit);
}

static const struct device *tgt_dev(const struct sbp2_target *tgt)
{
    return &tgt->unit->device;
}

static const struct device *lu_dev(const struct sbp2_logical_unit *lu)
{
    return &lu->tgt->unit->device;
}

/* Impossible login_id, to detect logout attempt before successful login */
#define INVALID_LOGIN_ID 0x10000

#define SBP2_ORB_TIMEOUT        2000U       /* Timeout in ms */
#define SBP2_ORB_NULL           0x80000000
#define SBP2_RETRY_LIMIT        0xf     /* 15 retries */
#define SBP2_CYCLE_LIMIT        (0xc8 << 12)    /* 200 125us cycles */

/*
 * There is no transport protocol limit to the CDB length,  but we implement
 * a fixed length only.  16 bytes is enough for disks larger than 2 TB.
 */
#define SBP2_MAX_CDB_SIZE       16

/*
 * The maximum SBP-2 data buffer size is 0xffff.  We quadlet-align this
 * for compatibility with earlier versions of this driver.
 */
#define SBP2_MAX_SEG_SIZE       0xfffc

/* 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_UNIT_UNIQUE_ID     0x8d
#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;
    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[SBP2_MAX_CDB_SIZE];
    } request;
    struct scsi_cmnd *cmd;
    struct sbp2_logical_unit *lu;

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

#define SBP2_ROM_VALUE_WILDCARD ~0         /* match all */
#define SBP2_ROM_VALUE_MISSING  0xff000000 /* not present in the unit dir. */

/*
 * 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.
 */
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 |
                      SBP2_WORKAROUND_POWER_CONDITION,
    },
    /* DViCO Momobay FX-3A with TSB42AA9A bridge */ {
        .firmware_revision  = 0x002800,
        .model          = 0x000000,
        .workarounds        = SBP2_WORKAROUND_POWER_CONDITION,
    },
    /* Initio bridges, actually only needed for some older ones */ {
        .firmware_revision  = 0x000200,
        .model          = SBP2_ROM_VALUE_WILDCARD,
        .workarounds        = SBP2_WORKAROUND_INQUIRY_36,
    },
    /* PL-3507 bridge with Prolific firmware */ {
        .firmware_revision  = 0x012800,
        .model          = SBP2_ROM_VALUE_WILDCARD,
        .workarounds        = SBP2_WORKAROUND_POWER_CONDITION,
    },
    /* Symbios bridge */ {
        .firmware_revision  = 0xa0b800,
        .model          = SBP2_ROM_VALUE_WILDCARD,
        .workarounds        = SBP2_WORKAROUND_128K_MAX_TRANS,
    },
    /* Datafab MD2-FW2 with Symbios/LSILogic SYM13FW500 bridge */ {
        .firmware_revision  = 0x002600,
        .model          = SBP2_ROM_VALUE_WILDCARD,
        .workarounds        = SBP2_WORKAROUND_128K_MAX_TRANS,
    },
    /*
     * iPod 2nd generation: needs 128k max transfer size workaround
     * iPod 3rd generation: needs fix capacity workaround
     */
    {
        .firmware_revision  = 0x0a2700,
        .model          = 0x000000,
        .workarounds        = SBP2_WORKAROUND_128K_MAX_TRANS |
                      SBP2_WORKAROUND_FIX_CAPACITY,
    },
    /* iPod 4th generation */ {
        .firmware_revision  = 0x0a2700,
        .model          = 0x000021,
        .workarounds        = SBP2_WORKAROUND_FIX_CAPACITY,
    },
    /* iPod mini */ {
        .firmware_revision  = 0x0a2700,
        .model          = 0x000022,
        .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, 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;
    unsigned long flags;

    if (tcode != TCODE_WRITE_BLOCK_REQUEST ||
        length < 8 || length > sizeof(status)) {
        fw_send_response(card, request, RCODE_TYPE_ERROR);
        return;
    }

    status.status  = be32_to_cpup(payload);
    status.orb_low = be32_to_cpup(payload + 4);
    memset(status.data, 0, sizeof(status.data));
    if (length > 8)
        memcpy(status.data, payload + 8, length - 8);

    if (STATUS_GET_SOURCE(status) == 2 || STATUS_GET_SOURCE(status) == 3) {
        dev_notice(lu_dev(lu),
               "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);
        kref_put(&orb->kref, free_orb); /* orb callback reference */
    } else {
        dev_err(lu_dev(lu), "status write for unknown ORB\n");
    }

    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);
        kref_put(&orb->kref, free_orb); /* orb callback reference */
    } else {
        spin_unlock_irqrestore(&card->lock, flags);
    }

    kref_put(&orb->kref, free_orb); /* transaction callback reference */
}

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 = target_parent_device(lu->tgt);
    struct sbp2_pointer orb_pointer;
    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);

    kref_get(&orb->kref); /* transaction callback reference */
    kref_get(&orb->kref); /* orb callback reference */

    fw_send_request(device->card, &orb->t, TCODE_WRITE_BLOCK_REQUEST,
            node_id, generation, device->max_speed, offset,
            &orb_pointer, 8, complete_transaction, orb);
}

static int sbp2_cancel_orbs(struct sbp2_logical_unit *lu)
{
    struct fw_device *device = target_parent_device(lu->tgt);
    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);
        kref_put(&orb->kref, free_orb); /* orb callback reference */
    }

    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 = target_parent_device(lu->tgt);
    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_NOIO);
    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(device->card->device, 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(device->card->device, 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) {
        dev_err(lu_dev(lu), "ORB reply timed out, rcode 0x%02x\n",
            orb->base.rcode);
        goto out;
    }

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

    if (STATUS_GET_RESPONSE(orb->status) != 0 ||
        STATUS_GET_SBP_STATUS(orb->status) != 0) {
        dev_err(lu_dev(lu), "error status: %d:%d\n",
             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 sbp2_agent_reset(struct sbp2_logical_unit *lu)
{
    struct fw_device *device = target_parent_device(lu->tgt);
    __be32 d = 0;

    fw_run_transaction(device->card, TCODE_WRITE_QUADLET_REQUEST,
               lu->tgt->node_id, lu->generation, device->max_speed,
               lu->command_block_agent_address + SBP2_AGENT_RESET,
               &d, 4);
}

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 = target_parent_device(lu->tgt);
    struct fw_transaction *t;
    static __be32 d;

    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,
            &d, 4, complete_agent_reset_write_no_wait, t);
}

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 = target_parent_device(tgt)->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 = target_parent_device(tgt)->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 = target_parent_device(tgt)->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);
}

/*
 * 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 = target_parent_device(lu->tgt);
    __be32 d = cpu_to_be32(SBP2_CYCLE_LIMIT | SBP2_RETRY_LIMIT);

    fw_run_transaction(device->card, TCODE_WRITE_QUADLET_REQUEST,
               lu->tgt->node_id, lu->generation, device->max_speed,
               CSR_REGISTER_BASE + CSR_BUSY_TIMEOUT, &d, 4);
}

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 = target_parent_device(tgt);
    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))
        return;

    generation    = device->generation;
    smp_rmb();    /* node IDs 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 {
            dev_err(tgt_dev(tgt), "failed to login to LUN %04x\n",
                lu->lun);
            /* Let any waiting I/O fail from now on. */
            sbp2_unblock(lu->tgt);
        }
        return;
    }

    tgt->node_id      = node_id;
    tgt->address_high = local_node_id << 16;
    smp_wmb();    /* node IDs must not be older than generation */
    lu->generation    = 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;

    dev_notice(tgt_dev(tgt), "logged in to LUN %04x (%d retries)\n",
           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);

        return;
    }

    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);

    return;

 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);
}

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 = target_parent_device(tgt);
    int generation, node_id, local_node_id;

    if (fw_device_is_shutdown(device))
        return;

    generation    = device->generation;
    smp_rmb();    /* node IDs 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) {
            dev_err(tgt_dev(tgt), "failed to reconnect\n");
            lu->retries = 0;
            PREPARE_DELAYED_WORK(&lu->work, sbp2_login);
        }
        sbp2_queue_work(lu, DIV_ROUND_UP(HZ, 5));

        return;
    }

    tgt->node_id      = node_id;
    tgt->address_high = local_node_id << 16;
    smp_wmb();    /* node IDs must not be older than generation */
    lu->generation    = generation;

    dev_notice(tgt_dev(tgt), "reconnected to LUN %04x (%d retries)\n",
           lu->lun, lu->retries);

    sbp2_agent_reset(lu);
    sbp2_cancel_orbs(lu);
    sbp2_conditionally_unblock(lu);
}

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->login_id = INVALID_LOGIN_ID;
    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 void sbp2_get_unit_unique_id(struct sbp2_target *tgt,
                    const u32 *leaf)
{
    if ((leaf[0] & 0xffff0000) == 0x00020000)
        tgt->guid = (u64)leaf[1] << 32 | leaf[2];
}

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

    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 */
            tgt->mgt_orb_timeout = (value >> 8 & 0xff) * 500;
            break;

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

        case SBP2_CSR_UNIT_UNIQUE_ID:
            sbp2_get_unit_unique_id(tgt, ci.p - 1 + value);
            break;

        case SBP2_CSR_LOGICAL_UNIT_DIRECTORY:
            /* Adjust for the increment in the iterator */
            if (sbp2_scan_logical_unit_dir(tgt, ci.p - 1 + value) < 0)
                return -ENOMEM;
            break;
        }
    }
    return 0;
}

/*
 * 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.
 */
static void sbp2_clamp_management_orb_timeout(struct sbp2_target *tgt)
{
    unsigned int timeout = tgt->mgt_orb_timeout;

    if (timeout > 40000)
        dev_notice(tgt_dev(tgt), "%ds mgt_ORB_timeout limited to 40s\n",
               timeout / 1000);

    tgt->mgt_orb_timeout = clamp_val(timeout, 5000, 40000);
}

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

    if (w)
        dev_notice(tgt_dev(tgt),
               "Please notify [email protected] "
               "if you need the workarounds parameter\n");

    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 != SBP2_ROM_VALUE_WILDCARD)
            continue;

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

static struct scsi_host_template scsi_driver_template;
static int sbp2_remove(struct device *dev);

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

    /* cannot (or should not) handle targets on the local node */
    if (device->is_local)
        return -ENODEV;

    if (dma_get_max_seg_size(device->card->device) > SBP2_MAX_SEG_SIZE)
        BUG_ON(dma_set_max_seg_size(device->card->device,
                        SBP2_MAX_SEG_SIZE));

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

    tgt = (struct sbp2_target *)shost->hostdata;
    dev_set_drvdata(&unit->device, tgt);
    tgt->unit = unit;
    INIT_LIST_HEAD(&tgt->lu_list);
    tgt->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];

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

    shost->max_cmd_len = SBP2_MAX_CDB_SIZE;

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

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

    firmware_revision = SBP2_ROM_VALUE_MISSING;
    model         = SBP2_ROM_VALUE_MISSING;

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

    sbp2_clamp_management_orb_timeout(tgt);
    sbp2_init_workarounds(tgt, model, firmware_revision);

    /*
     * At S100 we can do 512 bytes per packet, at S200 1024 bytes,
     * and so on up to 4096 bytes.  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.
     */
    tgt->max_payload = min3(device->max_speed + 7, 10U,
                device->card->max_receive - 1);

    /* 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, DIV_ROUND_UP(HZ, 5));

    return 0;

 fail_remove:
    sbp2_remove(dev);
    return -ENOMEM;

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

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

    fw_device_enable_phys_dma(fw_parent_device(unit));

    /*
     * 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);
    }
}

static int sbp2_remove(struct device *dev)
{
    struct fw_unit *unit = fw_unit(dev);
    struct fw_device *device = fw_parent_device(unit);
    struct sbp2_target *tgt = dev_get_drvdata(&unit->device);
    struct sbp2_logical_unit *lu, *next;
    struct Scsi_Host *shost =
        container_of((void *)tgt, struct Scsi_Host, hostdata[0]);
    struct scsi_device *sdev;

    /* prevent deadlocks */
    sbp2_unblock(tgt);

    list_for_each_entry_safe(lu, next, &tgt->lu_list, link) {
        cancel_delayed_work_sync(&lu->work);
        sdev = scsi_device_lookup(shost, 0, 0, sbp2_lun2int(lu->lun));
        if (sdev) {
            scsi_remove_device(sdev);
            scsi_device_put(sdev);
        }
        if (lu->login_id != INVALID_LOGIN_ID) {
            int generation, node_id;
            /*
             * tgt->node_id may be obsolete here if we failed
             * during initial login or after a bus reset where
             * the topology changed.
             */
            generation = device->generation;
            smp_rmb(); /* node_id vs. generation */
            node_id    = device->node_id;
            sbp2_send_management_orb(lu, node_id, 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);
    dev_notice(dev, "released target %d:0:0\n", shost->host_no);

    scsi_host_put(shost);
    return 0;
}

#define SBP2_UNIT_SPEC_ID_ENTRY 0x0000609e
#define SBP2_SW_VERSION_ENTRY   0x00010483

static const struct ieee1394_device_id sbp2_id_table[] = {
    {
        .match_flags  = IEEE1394_MATCH_SPECIFIER_ID |
                IEEE1394_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   = KBUILD_MODNAME,
        .bus    = &fw_bus_type,
        .probe  = sbp2_probe,
        .remove = sbp2_remove,
    },
    .update   = sbp2_update,
    .id_table = sbp2_id_table,
};

static void sbp2_unmap_scatterlist(struct device *card_device,
                   struct sbp2_command_orb *orb)
{
    scsi_dma_unmap(orb->cmd);

    if (orb->request.misc & cpu_to_be32(COMMAND_ORB_PAGE_TABLE_PRESENT))
        dma_unmap_single(card_device, orb->page_table_bus,
                 sizeof(orb->page_table), DMA_TO_DEVICE);
}

static unsigned int sbp2_status_to_sense_data(u8 *sbp2_status, u8 *sense_data)
{
    int sam_status;
    int sfmt = (sbp2_status[0] >> 6) & 0x03;

    if (sfmt == 2 || sfmt == 3) {
        /*
         * Reserved for future standardization (2) or
         * Status block format vendor-dependent (3)
         */
        return DID_ERROR << 16;
    }

    sense_data[0] = 0x70 | sfmt | (sbp2_status[1] & 0x80);
    sense_data[1] = 0x0;
    sense_data[2] = ((sbp2_status[1] << 1) & 0xe0) | (sbp2_status[1] & 0x0f);
    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 = target_parent_device(orb->lu->tgt);
    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);
    sbp2_unmap_scatterlist(device->card->device, orb);

    orb->cmd->result = result;
    orb->cmd->scsi_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 = scsi_sglist(orb->cmd);
    int i, n;

    n = scsi_dma_map(orb->cmd);
    if (n <= 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 (n == 1) {
        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;
    }

    for_each_sg(sg, sg, n, i) {
        orb->page_table[i].high = cpu_to_be32(sg_dma_len(sg) << 16);
        orb->page_table[i].low = cpu_to_be32(sg_dma_address(sg));
    }

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

    return 0;

 fail_page_table:
    scsi_dma_unmap(orb->cmd);
 fail:
    return -ENOMEM;
}

/* SCSI stack integration */

static int sbp2_scsi_queuecommand(struct Scsi_Host *shost,
                  struct scsi_cmnd *cmd)
{
    struct sbp2_logical_unit *lu = cmd->device->hostdata;
    struct fw_device *device = target_parent_device(lu->tgt);
    struct sbp2_command_orb *orb;
    int generation, retval = SCSI_MLQUEUE_HOST_BUSY;

    /*
     * Bidirectional commands are not yet implemented, and unknown
     * transfer direction not handled.
     */
    if (cmd->sc_data_direction == DMA_BIDIRECTIONAL) {
        dev_err(lu_dev(lu), "cannot handle bidirectional command\n");
        cmd->result = DID_ERROR << 16;
        cmd->scsi_done(cmd);
        return 0;
    }

    orb = kzalloc(sizeof(*orb), GFP_ATOMIC);
    if (orb == NULL) {
        dev_notice(lu_dev(lu), "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->cmd = cmd;
    orb->request.next.high = cpu_to_be32(SBP2_ORB_NULL);
    orb->request.misc = cpu_to_be32(
        COMMAND_ORB_MAX_PAYLOAD(lu->tgt->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);

    generation = device->generation;
    smp_rmb();    /* sbp2_map_scatterlist looks at tgt->address_high */

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

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

    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(device->card->device, orb->base.request_bus)) {
        sbp2_unmap_scatterlist(device->card->device, orb);
        goto out;
    }

    sbp2_send_orb(&orb->base, lu, lu->tgt->node_id, 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 does not require any alignment, but we set it anyway
     * for compatibility with earlier versions of this driver.
     */
    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;
    sdev->no_report_opcodes = 1;
    sdev->no_write_same = 1;

    if (sbp2_param_exclusive_login)
        sdev->manage_start_stop = 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_POWER_CONDITION)
        sdev->start_stop_pwr_cond = 1;

    if (lu->tgt->workarounds & SBP2_WORKAROUND_128K_MAX_TRANS)
        blk_queue_max_hw_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;

    dev_notice(lu_dev(lu), "sbp2_scsi_abort\n");
    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",
    .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 <[email protected]>");
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)
{
    return driver_register(&sbp2_driver.driver);
}

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

module_init(sbp2_init);
module_exit(sbp2_cleanup);