scsi.c

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/*
 * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
 *
 * 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 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., 51 Franklin Street, Fifth Floor, Boston, MA
 * 02110-1301, USA.
 *
 * You can also choose to distribute this program under the terms of
 * the Unmodified Binary Distribution Licence (as given in the file
 * COPYING.UBDL), provided that you have satisfied its requirements.
 */
 
FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
FILE_SECBOOT ( PERMITTED );
 
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <byteswap.h>
#include <errno.h>
#include <ipxe/list.h>
#include <ipxe/process.h>
#include <ipxe/xfer.h>
#include <ipxe/blockdev.h>
#include <ipxe/scsi.h>
 
/** @file
 *
 * SCSI block device
 *
 */
 
/** Maximum number of TEST UNIT READY retries */
#define SCSI_READY_MAX_RETRIES 10
 
/* Error numbers generated by SCSI sense data */
#define EIO_NO_SENSE __einfo_error ( EINFO_EIO_NO_SENSE )
#define EINFO_EIO_NO_SENSE \
        __einfo_uniqify ( EINFO_EIO, 0x00, "No sense" )
#define EIO_RECOVERED_ERROR __einfo_error ( EINFO_EIO_RECOVERED_ERROR )
#define EINFO_EIO_RECOVERED_ERROR \
        __einfo_uniqify ( EINFO_EIO, 0x01, "Recovered error" )
#define EIO_NOT_READY __einfo_error ( EINFO_EIO_NOT_READY )
#define EINFO_EIO_NOT_READY \
        __einfo_uniqify ( EINFO_EIO, 0x02, "Not ready" )
#define EIO_MEDIUM_ERROR __einfo_error ( EINFO_EIO_MEDIUM_ERROR )
#define EINFO_EIO_MEDIUM_ERROR \
        __einfo_uniqify ( EINFO_EIO, 0x03, "Medium error" )
#define EIO_HARDWARE_ERROR __einfo_error ( EINFO_EIO_HARDWARE_ERROR )
#define EINFO_EIO_HARDWARE_ERROR \
        __einfo_uniqify ( EINFO_EIO, 0x04, "Hardware error" )
#define EIO_ILLEGAL_REQUEST __einfo_error ( EINFO_EIO_ILLEGAL_REQUEST )
#define EINFO_EIO_ILLEGAL_REQUEST \
        __einfo_uniqify ( EINFO_EIO, 0x05, "Illegal request" )
#define EIO_UNIT_ATTENTION __einfo_error ( EINFO_EIO_UNIT_ATTENTION )
#define EINFO_EIO_UNIT_ATTENTION \
        __einfo_uniqify ( EINFO_EIO, 0x06, "Unit attention" )
#define EIO_DATA_PROTECT __einfo_error ( EINFO_EIO_DATA_PROTECT )
#define EINFO_EIO_DATA_PROTECT \
        __einfo_uniqify ( EINFO_EIO, 0x07, "Data protect" )
#define EIO_BLANK_CHECK __einfo_error ( EINFO_EIO_BLANK_CHECK )
#define EINFO_EIO_BLANK_CHECK \
        __einfo_uniqify ( EINFO_EIO, 0x08, "Blank check" )
#define EIO_VENDOR_SPECIFIC __einfo_error ( EINFO_EIO_VENDOR_SPECIFIC )
#define EINFO_EIO_VENDOR_SPECIFIC \
        __einfo_uniqify ( EINFO_EIO, 0x09, "Vendor specific" )
#define EIO_COPY_ABORTED __einfo_error ( EINFO_EIO_COPY_ABORTED )
#define EINFO_EIO_COPY_ABORTED \
        __einfo_uniqify ( EINFO_EIO, 0x0a, "Copy aborted" )
#define EIO_ABORTED_COMMAND __einfo_error ( EINFO_EIO_ABORTED_COMMAND )
#define EINFO_EIO_ABORTED_COMMAND \
        __einfo_uniqify ( EINFO_EIO, 0x0b, "Aborted command" )
#define EIO_RESERVED __einfo_error ( EINFO_EIO_RESERVED )
#define EINFO_EIO_RESERVED \
        __einfo_uniqify ( EINFO_EIO, 0x0c, "Reserved" )
#define EIO_VOLUME_OVERFLOW __einfo_error ( EINFO_EIO_VOLUME_OVERFLOW )
#define EINFO_EIO_VOLUME_OVERFLOW \
        __einfo_uniqify ( EINFO_EIO, 0x0d, "Volume overflow" )
#define EIO_MISCOMPARE __einfo_error ( EINFO_EIO_MISCOMPARE )
#define EINFO_EIO_MISCOMPARE \
        __einfo_uniqify ( EINFO_EIO, 0x0e, "Miscompare" )
#define EIO_COMPLETED __einfo_error ( EINFO_EIO_COMPLETED )
#define EINFO_EIO_COMPLETED \
        __einfo_uniqify ( EINFO_EIO, 0x0f, "Completed" )
#define EIO_SENSE( key )                                                \
        EUNIQ ( EINFO_EIO, (key), EIO_NO_SENSE, EIO_RECOVERED_ERROR,    \
                EIO_NOT_READY, EIO_MEDIUM_ERROR, EIO_HARDWARE_ERROR,    \
                EIO_ILLEGAL_REQUEST, EIO_UNIT_ATTENTION,                \
                EIO_DATA_PROTECT, EIO_BLANK_CHECK, EIO_VENDOR_SPECIFIC, \
                EIO_COPY_ABORTED, EIO_ABORTED_COMMAND, EIO_RESERVED,    \
                EIO_VOLUME_OVERFLOW, EIO_MISCOMPARE, EIO_COMPLETED )
 
/******************************************************************************
 *
 * Utility functions
 *
 ******************************************************************************
 */
 
/**
 * Parse SCSI LUN
 *
 * @v lun_string        LUN string representation
 * @v lun               LUN to fill in
 * @ret rc              Return status code
 */
int scsi_parse_lun ( const char *lun_string, struct scsi_lun *lun ) {
        char *p;
        int i;
 
        memset ( lun, 0, sizeof ( *lun ) );
        if ( lun_string ) {
                p = ( char * ) lun_string;
                for ( i = 0 ; i < 4 ; i++ ) {
                        lun->u16[i] = htons ( strtoul ( p, &p, 16 ) );
                        if ( *p == '\0' )
                                break;
                        if ( *p != '-' )
                                return -EINVAL;
                        p++;
                }
                if ( *p )
                        return -EINVAL;
        }
 
        return 0;
}
 
/**
 * Parse SCSI sense data
 *
 * @v data              Raw sense data
 * @v len               Length of raw sense data
 * @v sense             Descriptor-format sense data to fill in
 */
void scsi_parse_sense ( const void *data, size_t len,
                        struct scsi_sns_descriptor *sense ) {
        const union scsi_sns *sns = data;
 
        /* Avoid returning uninitialised data */
        memset ( sense, 0, sizeof ( *sense ) );
 
        /* Copy, assuming descriptor-format data */
        if ( len < sizeof ( sns->desc ) )
                return;
        memcpy ( sense, &sns->desc, sizeof ( *sense ) );
 
        /* Convert fixed-format to descriptor-format, if applicable */
        if ( len < sizeof ( sns->fixed ) )
                return;
        if ( ! SCSI_SENSE_FIXED ( sns->code ) )
                return;
        sense->additional = sns->fixed.additional;
}
 
/******************************************************************************
 *
 * Interface methods
 *
 ******************************************************************************
 */
 
/**
 * Issue SCSI command
 *
 * @v control           SCSI control interface
 * @v data              SCSI data interface
 * @v command           SCSI command
 * @ret tag             Command tag, or negative error
 */
int scsi_command ( struct interface *control, struct interface *data,
                   struct scsi_cmd *command ) {
        struct interface *dest;
        scsi_command_TYPE ( void * ) *op =
                intf_get_dest_op ( control, scsi_command, &dest );
        void *object = intf_object ( dest );
        int tap;
 
        if ( op ) {
                tap = op ( object, data, command );
        } else {
                /* Default is to fail to issue the command */
                tap = -EOPNOTSUPP;
        }
 
        intf_put ( dest );
        return tap;
}
 
/**
 * Report SCSI response
 *
 * @v interface         SCSI command interface
 * @v response          SCSI response
 */
void scsi_response ( struct interface *intf, struct scsi_rsp *response ) {
        struct interface *dest;
        scsi_response_TYPE ( void * ) *op =
                intf_get_dest_op ( intf, scsi_response, &dest );
        void *object = intf_object ( dest );
 
        if ( op ) {
                op ( object, response );
        } else {
                /* Default is to ignore the response */
        }
 
        intf_put ( dest );
}
 
/******************************************************************************
 *
 * SCSI devices and commands
 *
 ******************************************************************************
 */
 
/** A SCSI device */
struct scsi_device {
        /** Reference count */
        struct refcnt refcnt;
        /** Block control interface */
        struct interface block;
        /** SCSI control interface */
        struct interface scsi;
 
        /** SCSI LUN */
        struct scsi_lun lun;
        /** Flags */
        unsigned int flags;
 
        /** TEST UNIT READY interface */
        struct interface ready;
        /** TEST UNIT READY process */
        struct process process;
        /** TEST UNIT READY retry count */
        unsigned int retries;
 
        /** List of commands */
        struct list_head cmds;
};
 
/** SCSI device flags */
enum scsi_device_flags {
        /** TEST UNIT READY has been issued */
        SCSIDEV_UNIT_TESTED = 0x0001,
        /** TEST UNIT READY has completed successfully */
        SCSIDEV_UNIT_READY = 0x0002,
};
 
/** A SCSI command */
struct scsi_command {
        /** Reference count */
        struct refcnt refcnt;
        /** SCSI device */
        struct scsi_device *scsidev;
        /** List of SCSI commands */
        struct list_head list;
 
        /** Block data interface */
        struct interface block;
        /** SCSI data interface */
        struct interface scsi;
 
        /** Command type */
        struct scsi_command_type *type;
        /** Starting logical block address */
        uint64_t lba;
        /** Number of blocks */
        unsigned int count;
        /** Data buffer */
        void *buffer;
        /** Length of data buffer */
        size_t len;
        /** Command tag */
        uint32_t tag;
 
        /** Private data */
        uint8_t priv[0];
};
 
/** A SCSI command type */
struct scsi_command_type {
        /** Name */
        const char *name;
        /** Additional working space */
        size_t priv_len;
        /**
         * Construct SCSI command IU
         *
         * @v scsicmd           SCSI command
         * @v command           SCSI command IU
         */
        void ( * cmd ) ( struct scsi_command *scsicmd,
                         struct scsi_cmd *command );
        /**
         * Handle SCSI command completion
         *
         * @v scsicmd           SCSI command
         * @v rc                Reason for completion
         */
        void ( * done ) ( struct scsi_command *scsicmd, int rc );
};
 
/**
 * Get reference to SCSI device
 *
 * @v scsidev           SCSI device
 * @ret scsidev         SCSI device
 */
static inline __attribute__ (( always_inline )) struct scsi_device *
scsidev_get ( struct scsi_device *scsidev ) {
        ref_get ( &scsidev->refcnt );
        return scsidev;
}
 
/**
 * Drop reference to SCSI device
 *
 * @v scsidev           SCSI device
 */
static inline __attribute__ (( always_inline )) void
scsidev_put ( struct scsi_device *scsidev ) {
        ref_put ( &scsidev->refcnt );
}
 
/**
 * Get reference to SCSI command
 *
 * @v scsicmd           SCSI command
 * @ret scsicmd         SCSI command
 */
static inline __attribute__ (( always_inline )) struct scsi_command *
scsicmd_get ( struct scsi_command *scsicmd ) {
        ref_get ( &scsicmd->refcnt );
        return scsicmd;
}
 
/**
 * Drop reference to SCSI command
 *
 * @v scsicmd           SCSI command
 */
static inline __attribute__ (( always_inline )) void
scsicmd_put ( struct scsi_command *scsicmd ) {
        ref_put ( &scsicmd->refcnt );
}
 
/**
 * Get SCSI command private data
 *
 * @v scsicmd           SCSI command
 * @ret priv            Private data
 */
static inline __attribute__ (( always_inline )) void *
scsicmd_priv ( struct scsi_command *scsicmd ) {
        return scsicmd->priv;
}
 
/**
 * Free SCSI command
 *
 * @v refcnt            Reference count
 */
static void scsicmd_free ( struct refcnt *refcnt ) {
        struct scsi_command *scsicmd =
                container_of ( refcnt, struct scsi_command, refcnt );
 
        /* Drop reference to SCSI device */
        scsidev_put ( scsicmd->scsidev );
 
        /* Free command */
        free ( scsicmd );
}
 
/**
 * Close SCSI command
 *
 * @v scsicmd           SCSI command
 * @v rc                Reason for close
 */
static void scsicmd_close ( struct scsi_command *scsicmd, int rc ) {
        struct scsi_device *scsidev = scsicmd->scsidev;
 
        if ( rc != 0 ) {
                DBGC ( scsidev, "SCSI %p tag %08x closed: %s\n",
                       scsidev, scsicmd->tag, strerror ( rc ) );
        }
 
        /* Remove from list of commands */
        list_del ( &scsicmd->list );
 
        /* Shut down interfaces */
        intfs_shutdown ( rc, &scsicmd->scsi, &scsicmd->block, NULL );
 
        /* Drop list's reference */
        scsicmd_put ( scsicmd );
}
 
/**
 * Construct and issue SCSI command
 *
 * @ret rc              Return status code
 */
static int scsicmd_command ( struct scsi_command *scsicmd ) {
        struct scsi_device *scsidev = scsicmd->scsidev;
        struct scsi_cmd command;
        int tag;
        int rc;
 
        /* Construct command */
        memset ( &command, 0, sizeof ( command ) );
        memcpy ( &command.lun, &scsidev->lun, sizeof ( command.lun ) );
        xferbuf_void_init ( &command.data_in );
        xferbuf_void_init ( &command.data_out );
        scsicmd->type->cmd ( scsicmd, &command );
 
        /* Issue command */
        if ( ( tag = scsi_command ( &scsidev->scsi, &scsicmd->scsi,
                                    &command ) ) < 0 ) {
                rc = tag;
                DBGC ( scsidev, "SCSI %p could not issue command: %s\n",
                       scsidev, strerror ( rc ) );
                return rc;
        }
 
        /* Record tag */
        if ( scsicmd->tag ) {
                DBGC ( scsidev, "SCSI %p tag %08x is now tag %08x\n",
                       scsidev, scsicmd->tag, tag );
        }
        scsicmd->tag = tag;
        DBGC2 ( scsidev, "SCSI %p tag %08x %s " SCSI_CDB_FORMAT "\n",
                scsidev, scsicmd->tag, scsicmd->type->name,
                SCSI_CDB_DATA ( command.cdb ) );
 
        return 0;
}
 
/**
 * Handle SCSI command completion
 *
 * @v scsicmd           SCSI command
 * @v rc                Reason for close
 */
static void scsicmd_done ( struct scsi_command *scsicmd, int rc ) {
 
        /* Restart SCSI interface */
        intf_restart ( &scsicmd->scsi, rc );
 
        /* Hand over to the command completion handler */
        scsicmd->type->done ( scsicmd, rc );
}
 
/**
 * Handle SCSI response
 *
 * @v scsicmd           SCSI command
 * @v response          SCSI response
 */
static void scsicmd_response ( struct scsi_command *scsicmd,
                               struct scsi_rsp *response ) {
        struct scsi_device *scsidev = scsicmd->scsidev;
        size_t overrun;
        size_t underrun;
        int rc;
 
        if ( response->status == 0 ) {
                scsicmd_done ( scsicmd, 0 );
        } else {
                DBGC ( scsidev, "SCSI %p tag %08x status %02x",
                       scsidev, scsicmd->tag, response->status );
                if ( response->overrun > 0 ) {
                        overrun = response->overrun;
                        DBGC ( scsidev, " overrun +%zd", overrun );
                } else if ( response->overrun < 0 ) {
                        underrun = -(response->overrun);
                        DBGC ( scsidev, " underrun -%zd", underrun );
                }
                DBGC ( scsidev, " sense %02x key %02x additional %04x\n",
                       ( response->sense.code & SCSI_SENSE_CODE_MASK ),
                       ( response->sense.key & SCSI_SENSE_KEY_MASK ),
                       ntohs ( response->sense.additional ) );
 
                /* Construct error number from sense data */
                rc = -EIO_SENSE ( response->sense.key & SCSI_SENSE_KEY_MASK );
                scsicmd_done ( scsicmd, rc );
        }
}
 
/**
 * Construct SCSI READ command
 *
 * @v scsicmd           SCSI command
 * @v command           SCSI command IU
 */
static void scsicmd_read_cmd ( struct scsi_command *scsicmd,
                               struct scsi_cmd *command ) {
 
        if ( ( scsicmd->lba + scsicmd->count ) > SCSI_MAX_BLOCK_10 ) {
                /* Use READ (16) */
                command->cdb.read16.opcode = SCSI_OPCODE_READ_16;
                command->cdb.read16.lba = cpu_to_be64 ( scsicmd->lba );
                command->cdb.read16.len = cpu_to_be32 ( scsicmd->count );
        } else {
                /* Use READ (10) */
                command->cdb.read10.opcode = SCSI_OPCODE_READ_10;
                command->cdb.read10.lba = cpu_to_be32 ( scsicmd->lba );
                command->cdb.read10.len = cpu_to_be16 ( scsicmd->count );
        }
        xferbuf_fixed_init ( &command->data_in, scsicmd->buffer,
                             scsicmd->len );
}
 
/** SCSI READ command type */
static struct scsi_command_type scsicmd_read = {
        .name = "READ",
        .cmd = scsicmd_read_cmd,
        .done = scsicmd_close,
};
 
/**
 * Construct SCSI WRITE command
 *
 * @v scsicmd           SCSI command
 * @v command           SCSI command IU
 */
static void scsicmd_write_cmd ( struct scsi_command *scsicmd,
                                struct scsi_cmd *command ) {
 
        if ( ( scsicmd->lba + scsicmd->count ) > SCSI_MAX_BLOCK_10 ) {
                /* Use WRITE (16) */
                command->cdb.write16.opcode = SCSI_OPCODE_WRITE_16;
                command->cdb.write16.lba = cpu_to_be64 ( scsicmd->lba );
                command->cdb.write16.len = cpu_to_be32 ( scsicmd->count );
        } else {
                /* Use WRITE (10) */
                command->cdb.write10.opcode = SCSI_OPCODE_WRITE_10;
                command->cdb.write10.lba = cpu_to_be32 ( scsicmd->lba );
                command->cdb.write10.len = cpu_to_be16 ( scsicmd->count );
        }
        xferbuf_fixed_init ( &command->data_out, scsicmd->buffer,
                             scsicmd->len );
}
 
/** SCSI WRITE command type */
static struct scsi_command_type scsicmd_write = {
        .name = "WRITE",
        .cmd = scsicmd_write_cmd,
        .done = scsicmd_close,
};
 
/** SCSI READ CAPACITY private data */
struct scsi_read_capacity_private {
        /** Use READ CAPACITY (16) */
        int use16;
        /** Data buffer for READ CAPACITY commands */
        union {
                /** Data buffer for READ CAPACITY (10) */
                struct scsi_capacity_10 capacity10;
                /** Data buffer for READ CAPACITY (16) */
                struct scsi_capacity_16 capacity16;
        } capacity;
};
 
/**
 * Construct SCSI READ CAPACITY command
 *
 * @v scsicmd           SCSI command
 * @v command           SCSI command IU
 */
static void scsicmd_read_capacity_cmd ( struct scsi_command *scsicmd,
                                        struct scsi_cmd *command ) {
        struct scsi_read_capacity_private *priv = scsicmd_priv ( scsicmd );
        struct scsi_cdb_read_capacity_16 *readcap16 = &command->cdb.readcap16;
        struct scsi_cdb_read_capacity_10 *readcap10 = &command->cdb.readcap10;
        struct scsi_capacity_16 *capacity16 = &priv->capacity.capacity16;
        struct scsi_capacity_10 *capacity10 = &priv->capacity.capacity10;
 
        if ( priv->use16 ) {
                /* Use READ CAPACITY (16) */
                readcap16->opcode = SCSI_OPCODE_SERVICE_ACTION_IN;
                readcap16->service_action =
                        SCSI_SERVICE_ACTION_READ_CAPACITY_16;
                readcap16->len = cpu_to_be32 ( sizeof ( *capacity16 ) );
                xferbuf_fixed_init ( &command->data_in, capacity16,
                                     sizeof ( *capacity16 ) );
        } else {
                /* Use READ CAPACITY (10) */
                readcap10->opcode = SCSI_OPCODE_READ_CAPACITY_10;
                xferbuf_fixed_init ( &command->data_in, capacity10,
                                     sizeof ( *capacity10 ) );
        }
}
 
/**
 * Handle SCSI READ CAPACITY command completion
 *
 * @v scsicmd           SCSI command
 * @v rc                Reason for completion
 */
static void scsicmd_read_capacity_done ( struct scsi_command *scsicmd,
                                         int rc ) {
        struct scsi_device *scsidev = scsicmd->scsidev;
        struct scsi_read_capacity_private *priv = scsicmd_priv ( scsicmd );
        struct scsi_capacity_16 *capacity16 = &priv->capacity.capacity16;
        struct scsi_capacity_10 *capacity10 = &priv->capacity.capacity10;
        struct block_device_capacity capacity;
 
        /* Close if command failed */
        if ( rc != 0 ) {
                scsicmd_close ( scsicmd, rc );
                return;
        }
 
        /* Extract capacity */
        if ( priv->use16 ) {
                capacity.blocks = ( be64_to_cpu ( capacity16->lba ) + 1 );
                capacity.blksize = be32_to_cpu ( capacity16->blksize );
        } else {
                capacity.blocks = ( be32_to_cpu ( capacity10->lba ) + 1 );
                capacity.blksize = be32_to_cpu ( capacity10->blksize );
 
                /* If capacity range was exceeded (i.e. capacity.lba
                 * was 0xffffffff, meaning that blockdev->blocks is
                 * now zero), use READ CAPACITY (16) instead.  READ
                 * CAPACITY (16) is not mandatory, so we can't just
                 * use it straight off.
                 */
                if ( capacity.blocks == 0 ) {
                        priv->use16 = 1;
                        if ( ( rc = scsicmd_command ( scsicmd ) ) != 0 ) {
                                scsicmd_close ( scsicmd, rc );
                                return;
                        }
                        return;
                }
        }
        capacity.max_count = -1U;
 
        /* Allow transport layer to update capacity */
        block_capacity ( &scsidev->scsi, &capacity );
 
        /* Return capacity to caller */
        block_capacity ( &scsicmd->block, &capacity );
 
        /* Close command */
        scsicmd_close ( scsicmd, 0 );
}
 
/** SCSI READ CAPACITY command type */
static struct scsi_command_type scsicmd_read_capacity = {
        .name = "READ CAPACITY",
        .priv_len = sizeof ( struct scsi_read_capacity_private ),
        .cmd = scsicmd_read_capacity_cmd,
        .done = scsicmd_read_capacity_done,
};
 
/**
 * Construct SCSI TEST UNIT READY command
 *
 * @v scsicmd           SCSI command
 * @v command           SCSI command IU
 */
static void scsicmd_test_unit_ready_cmd ( struct scsi_command *scsicmd __unused,
                                          struct scsi_cmd *command ) {
        struct scsi_cdb_test_unit_ready *testready = &command->cdb.testready;
 
        testready->opcode = SCSI_OPCODE_TEST_UNIT_READY;
}
 
/** SCSI TEST UNIT READY command type */
static struct scsi_command_type scsicmd_test_unit_ready = {
        .name = "TEST UNIT READY",
        .cmd = scsicmd_test_unit_ready_cmd,
        .done = scsicmd_close,
};
 
/** SCSI command block interface operations */
static struct interface_operation scsicmd_block_op[] = {
        INTF_OP ( intf_close, struct scsi_command *, scsicmd_close ),
};
 
/** SCSI command block interface descriptor */
static struct interface_descriptor scsicmd_block_desc =
        INTF_DESC_PASSTHRU ( struct scsi_command, block,
                             scsicmd_block_op, scsi );
 
/** SCSI command SCSI interface operations */
static struct interface_operation scsicmd_scsi_op[] = {
        INTF_OP ( intf_close, struct scsi_command *, scsicmd_done ),
        INTF_OP ( scsi_response, struct scsi_command *, scsicmd_response ),
};
 
/** SCSI command SCSI interface descriptor */
static struct interface_descriptor scsicmd_scsi_desc =
        INTF_DESC_PASSTHRU ( struct scsi_command, scsi,
                             scsicmd_scsi_op, block );
 
/**
 * Create SCSI command
 *
 * @v scsidev           SCSI device
 * @v block             Block data interface
 * @v type              SCSI command type
 * @v lba               Starting logical block address
 * @v count             Number of blocks to transfer
 * @v buffer            Data buffer
 * @v len               Length of data buffer
 * @ret rc              Return status code
 */
static int scsidev_command ( struct scsi_device *scsidev,
                             struct interface *block,
                             struct scsi_command_type *type,
                             uint64_t lba, unsigned int count,
                             void *buffer, size_t len ) {
        struct scsi_command *scsicmd;
        int rc;
 
        /* Allocate and initialise structure */
        scsicmd = zalloc ( sizeof ( *scsicmd ) + type->priv_len );
        if ( ! scsicmd ) {
                rc = -ENOMEM;
                goto err_zalloc;
        }
        ref_init ( &scsicmd->refcnt, scsicmd_free );
        intf_init ( &scsicmd->block, &scsicmd_block_desc, &scsicmd->refcnt );
        intf_init ( &scsicmd->scsi, &scsicmd_scsi_desc,
                    &scsicmd->refcnt );
        scsicmd->scsidev = scsidev_get ( scsidev );
        list_add ( &scsicmd->list, &scsidev->cmds );
        scsicmd->type = type;
        scsicmd->lba = lba;
        scsicmd->count = count;
        scsicmd->buffer = buffer;
        scsicmd->len = len;
 
        /* Issue SCSI command */
        if ( ( rc = scsicmd_command ( scsicmd ) ) != 0 )
                goto err_command;
 
        /* Attach to parent interface, transfer reference to list, and return */
        intf_plug_plug ( &scsicmd->block, block );
        return 0;
 
 err_command:
        scsicmd_close ( scsicmd, rc );
        ref_put ( &scsicmd->refcnt );
 err_zalloc:
        return rc;
}
 
/**
 * Issue SCSI block read
 *
 * @v scsidev           SCSI device
 * @v block             Block data interface
 * @v lba               Starting logical block address
 * @v count             Number of blocks to transfer
 * @v buffer            Data buffer
 * @v len               Length of data buffer
 * @ret rc              Return status code
 
 */
static int scsidev_read ( struct scsi_device *scsidev,
                          struct interface *block,
                          uint64_t lba, unsigned int count,
                          void *buffer, size_t len ) {
        return scsidev_command ( scsidev, block, &scsicmd_read,
                                 lba, count, buffer, len );
}
 
/**
 * Issue SCSI block write
 *
 * @v scsidev           SCSI device
 * @v block             Block data interface
 * @v lba               Starting logical block address
 * @v count             Number of blocks to transfer
 * @v buffer            Data buffer
 * @v len               Length of data buffer
 * @ret rc              Return status code
 */
static int scsidev_write ( struct scsi_device *scsidev,
                           struct interface *block,
                           uint64_t lba, unsigned int count,
                           void *buffer, size_t len ) {
        return scsidev_command ( scsidev, block, &scsicmd_write,
                                 lba, count, buffer, len );
}
 
/**
 * Read SCSI device capacity
 *
 * @v scsidev           SCSI device
 * @v block             Block data interface
 * @ret rc              Return status code
 */
static int scsidev_read_capacity ( struct scsi_device *scsidev,
                                   struct interface *block ) {
        return scsidev_command ( scsidev, block, &scsicmd_read_capacity,
                                 0, 0, NULL, 0 );
}
 
/**
 * Test to see if SCSI device is ready
 *
 * @v scsidev           SCSI device
 * @v block             Block data interface
 * @ret rc              Return status code
 */
static int scsidev_test_unit_ready ( struct scsi_device *scsidev,
                                     struct interface *block ) {
        return scsidev_command ( scsidev, block, &scsicmd_test_unit_ready,
                                 0, 0, NULL, 0 );
}
 
/**
 * Check SCSI device flow-control window
 *
 * @v scsidev           SCSI device
 * @ret len             Length of window
 */
static size_t scsidev_window ( struct scsi_device *scsidev ) {
 
        /* Refuse commands until unit is confirmed ready */
        if ( ! ( scsidev->flags & SCSIDEV_UNIT_READY ) )
                return 0;
 
        return xfer_window ( &scsidev->scsi );
}
 
/**
 * Close SCSI device
 *
 * @v scsidev           SCSI device
 * @v rc                Reason for close
 */
static void scsidev_close ( struct scsi_device *scsidev, int rc ) {
        struct scsi_command *scsicmd;
        struct scsi_command *tmp;
 
        /* Stop process */
        process_del ( &scsidev->process );
 
        /* Shut down interfaces */
        intfs_shutdown ( rc, &scsidev->block, &scsidev->scsi, &scsidev->ready,
                         NULL );
 
        /* Shut down any remaining commands */
        list_for_each_entry_safe ( scsicmd, tmp, &scsidev->cmds, list )
                scsicmd_close ( scsicmd, rc );
}
 
/** SCSI device block interface operations */
static struct interface_operation scsidev_block_op[] = {
        INTF_OP ( xfer_window, struct scsi_device *, scsidev_window ),
        INTF_OP ( block_read, struct scsi_device *, scsidev_read ),
        INTF_OP ( block_write, struct scsi_device *, scsidev_write ),
        INTF_OP ( block_read_capacity, struct scsi_device *,
                  scsidev_read_capacity ),
        INTF_OP ( intf_close, struct scsi_device *, scsidev_close ),
};
 
/** SCSI device block interface descriptor */
static struct interface_descriptor scsidev_block_desc =
        INTF_DESC_PASSTHRU ( struct scsi_device, block,
                             scsidev_block_op, scsi );
 
/**
 * Handle SCSI TEST UNIT READY response
 *
 * @v scsidev           SCSI device
 * @v rc                Reason for close
 */
static void scsidev_ready ( struct scsi_device *scsidev, int rc ) {
 
        /* Shut down interface */
        intf_restart ( &scsidev->ready, rc );
 
        /* Mark device as ready, if applicable */
        if ( rc == 0 ) {
                DBGC ( scsidev, "SCSI %p unit is ready\n", scsidev );
                scsidev->flags |= SCSIDEV_UNIT_READY;
                xfer_window_changed ( &scsidev->block );
                return;
        }
        DBGC ( scsidev, "SCSI %p not ready: %s\n", scsidev, strerror ( rc ) );
 
        /* SCSI targets have an annoying habit of returning occasional
         * pointless "error" messages such as "power-on occurred", so
         * we have to be prepared to retry commands.
         *
         * For most commands, we rely on the caller (e.g. the generic
         * SAN device layer) to retry commands as needed.  However, a
         * TEST UNIT READY failure is used as an indication that the
         * whole SCSI device is unavailable and should be closed.  We
         * must therefore perform this retry loop within the SCSI
         * layer.
         */
        if ( scsidev->retries++ < SCSI_READY_MAX_RETRIES ) {
                DBGC ( scsidev, "SCSI %p retrying (retry %d)\n",
                       scsidev, scsidev->retries );
                scsidev->flags &= ~SCSIDEV_UNIT_TESTED;
                process_add ( &scsidev->process );
                return;
        }
 
        /* Close device */
        DBGC ( scsidev, "SCSI %p never became ready: %s\n",
               scsidev, strerror ( rc ) );
        scsidev_close ( scsidev, rc );
}
 
/** SCSI device TEST UNIT READY interface operations */
static struct interface_operation scsidev_ready_op[] = {
        INTF_OP ( intf_close, struct scsi_device *, scsidev_ready ),
};
 
/** SCSI device TEST UNIT READY interface descriptor */
static struct interface_descriptor scsidev_ready_desc =
        INTF_DESC ( struct scsi_device, ready, scsidev_ready_op );
 
/**
 * SCSI TEST UNIT READY process
 *
 * @v scsidev           SCSI device
 */
static void scsidev_step ( struct scsi_device *scsidev ) {
        int rc;
 
        /* Do nothing if we have already issued TEST UNIT READY */
        if ( scsidev->flags & SCSIDEV_UNIT_TESTED )
                return;
 
        /* Wait until underlying SCSI device is ready */
        if ( xfer_window ( &scsidev->scsi ) == 0 )
                return;
 
        DBGC ( scsidev, "SCSI %p waiting for unit to become ready\n",
               scsidev );
 
        /* Mark TEST UNIT READY as sent */
        scsidev->flags |= SCSIDEV_UNIT_TESTED;
 
        /* Issue TEST UNIT READY command */
        if ( ( rc = scsidev_test_unit_ready ( scsidev, &scsidev->ready )) !=0){
                scsidev_close ( scsidev, rc );
                return;
        }
}
 
/** SCSI device SCSI interface operations */
static struct interface_operation scsidev_scsi_op[] = {
        INTF_OP ( xfer_window_changed, struct scsi_device *, scsidev_step ),
        INTF_OP ( intf_close, struct scsi_device *, scsidev_close ),
};
 
/** SCSI device SCSI interface descriptor */
static struct interface_descriptor scsidev_scsi_desc =
        INTF_DESC_PASSTHRU ( struct scsi_device, scsi,
                             scsidev_scsi_op, block );
 
/** SCSI device process descriptor */
static struct process_descriptor scsidev_process_desc =
        PROC_DESC_ONCE ( struct scsi_device, process, scsidev_step );
 
/**
 * Open SCSI device
 *
 * @v block             Block control interface
 * @v scsi              SCSI control interface
 * @v lun               SCSI LUN
 * @ret rc              Return status code
 */
int scsi_open ( struct interface *block, struct interface *scsi,
                struct scsi_lun *lun ) {
        struct scsi_device *scsidev;
 
        /* Allocate and initialise structure */
        scsidev = zalloc ( sizeof ( *scsidev ) );
        if ( ! scsidev )
                return -ENOMEM;
        ref_init ( &scsidev->refcnt, NULL );
        intf_init ( &scsidev->block, &scsidev_block_desc, &scsidev->refcnt );
        intf_init ( &scsidev->scsi, &scsidev_scsi_desc, &scsidev->refcnt );
        intf_init ( &scsidev->ready, &scsidev_ready_desc, &scsidev->refcnt );
        process_init ( &scsidev->process, &scsidev_process_desc,
                       &scsidev->refcnt );
        INIT_LIST_HEAD ( &scsidev->cmds );
        memcpy ( &scsidev->lun, lun, sizeof ( scsidev->lun ) );
        DBGC ( scsidev, "SCSI %p created for LUN " SCSI_LUN_FORMAT "\n",
               scsidev, SCSI_LUN_DATA ( scsidev->lun ) );
 
        /* Attach to SCSI and parent interfaces, mortalise self, and return */
        intf_plug_plug ( &scsidev->scsi, scsi );
        intf_plug_plug ( &scsidev->block, block );
        ref_put ( &scsidev->refcnt );
        return 0;
}