After the probe(9E) routine has verified that the expected device is present, attach(9E) is called. attach() performs these tasks:
Allocates and initializes any per-instance data.
Creates minor device node information.
Restores the hardware state of a device after a suspension of the device or the system. See attach() Entry Point for details.
A SCSI target driver needs to call scsi_probe(9F) again to retrieve the device's inquiry data. The driver must also create 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 that is suitable for consistent DMA. scsi_alloc_consistent_buf() then 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 by creating a SCSI request sense command.
Note that a SCSI device is not self-identifying and does not have a reg property. As a result, the driver must set the pm-hardware-state property. Setting pm-hardware-state informs the framework that this device needs to be suspended and then resumed.
The following example shows the SCSI target driver's attach() 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 the "Directory Memory Access (DMA)" */ /* chapter in this book. */ 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); }