attach(9E)

After the probe(9E) routine has verified that the expected device is present, attach(9E) is called. This routine allocates and initializes any per-instance data, creates minor device node information, and restores the hardware state of a device when the device or the system has been suspended. See "attach(9E)" for details of this. In addition to these steps, a SCSI target driver again calls scsi_probe(9F) to retrieve the device's inquiry data and also creates a SCSI request sense packet. If the attach is successful, the attach function should not call scsi_unprobe(9F).

Three routines are used to create the request sense packet: scsi_alloc_consistent_buf(9F), scsi_init_pkt(9F), and scsi_setup_cdb(9F). scsi_alloc_consistent_buf(9F) allocates a buffer suitable for consistent DMA and returns a pointer to a buf(9S) structure. The advantage of a consistent buffer is that no explicit synchronization of the data is required. In other words, the target driver can access the data after the callback. The sd_sense element of the device's scsi_device(9S) structure must be initialized with the address of the sense buffer. scsi_init_pkt(9F) creates and partially initializes a scsi_pkt(9S) structure. scsi_setup_cdb(9F) creates a SCSI command descriptor block, in this case creating a SCSI request sense command.

Note that since a SCSI device is not self-identifying and does not have a reg property, the driver must set the pm-hardware-state property to inform the framework that this device needs to be suspended and resumed.

Example 14-2 shows the SCSI target driver's attach(9E) routine.

Example 14-2 SCSI Target Driver attach(9E) Routine

static int
xxattach(dev_info_t *dip, ddi_attach_cmd_t cmd)
{
    struct xxstate             *xsp;
    struct scsi_pkt            *rqpkt = NULL;
    struct scsi_device         *sdp;
    struct buf                 *bp = NULL;
    int                        instance;
    instance = ddi_get_instance(dip);
    switch (cmd) {
            case DDI_ATTACH:
                break;
            case DDI_RESUME:
                For information, see Chapter 9 
            default:
                return (DDI_FAILURE);
    }
    allocate a state structure and initialize it
    ...
    xsp = ddi_get_soft_state(statep, instance);
    sdp = (struct scsi_device *)ddi_get_driver_private(dip);
    /*
     * Cross-link the state and scsi_device(9S) structures.
     */
    sdp->sd_private = (caddr_t)xsp;
    xsp->sdp = sdp;
    call scsi_probe(9F) again to get and validate inquiry data
    /*
     * Allocate a request sense buffer. The buf(9S) structure
     * is set to NULL to tell the routine to allocate a new
     * one. The callback function is set to NULL_FUNC to tell
     * the routine to return failure immediately if no
     * resources are available.
     */
    bp = scsi_alloc_consistent_buf(&sdp->sd_address, NULL,
        SENSE_LENGTH, B_READ, NULL_FUNC, NULL);
    if (bp == NULL)
            goto failed;
    /*
     * Create a Request Sense scsi_pkt(9S) structure.
     */
    rqpkt = scsi_init_pkt(&sdp->sd_address, NULL, bp,
        CDB_GROUP0, 1, 0, PKT_CONSISTENT, NULL_FUNC, NULL);
    if (rqpkt == NULL)
            goto failed;
    /*
     * scsi_alloc_consistent_buf(9F) returned a buf(9S) structure.
     * The actual buffer address is in b_un.b_addr.
     */
    sdp->sd_sense = (struct scsi_extended_sense *)bp->b_un.b_addr;
    /*
     * Create a Group0 CDB for the Request Sense command
     */
    if (scsi_setup_cdb((union scsi_cdb *)rqpkt->pkt_cdbp,
            SCMD_REQUEST_SENSE, 0, SENSE__LENGTH, 0) == 0)
             goto failed;;
    /*
     * Fill in the rest of the scsi_pkt structure.
     * xxcallback() is the private command completion routine.
     */
    rqpkt->pkt_comp = xxcallback;
    rqpkt->pkt_time = 30; /* 30 second command timeout */
    rqpkt->pkt_flags |= FLAG_SENSING;
    xsp->rqs = rqpkt;
    xsp->rqsbuf = bp;
    create minor nodes, report device, and do any other initialization
    /*
     * Since the device does not have the 'reg' property,
     * cpr will not call its DDI_SUSPEND/DDI_RESUME entries.
     * The following code is to tell cpr that this device
     * needs to be suspended and resumed.
     */
    (void) ddi_prop_update_string(device, dip,
         "pm-hardware-state", "needs-suspend-resume");
    xsp->open = 0;
    return (DDI_SUCCESS);
failed:
    if (bp)
            scsi_free_consistent_buf(bp);
    if (rqpkt)
            scsi_destroy_pkt(rqpkt);
    sdp->sd_private = (caddr_t)NULL;
    sdp->sd_sense = NULL;
    scsi_unprobe(sdp);
    free any other resources, such as the state structure
    return (DDI_FAILURE);
}