Entry Points for Module Initialization

This section describes the entry points for operations that are performed by SCSI HBA drivers.

The following code for a SCSI HBA driver illustrates a representative dev_ops(9S) structure. The driver must initialize the devo_bus_ops field in this structure to NULL. A SCSI HBA driver can provide leaf driver interfaces for special purposes, in which case the devo_cb_ops field might point to a cb_ops(9S) structure. In this example, no leaf driver interfaces are exported, so the devo_cb_ops field is initialized to NULL.

_init() Entry Point (SCSI HBA Drivers)

The _init(9E) function initializes a loadable module. _init() is called before any other routine in the loadable module.

In a SCSI HBA, the _init() function must call scsi_hba_init(9F) to inform the framework of the existence of the HBA driver before calling mod_install(9F). If scsi_hba__init() returns a nonzero value,_init() should return this value. Otherwise, _init() must return the value returned by mod_install(9F).

The driver should initialize any required global state before calling mod_install(9F).

If mod_install() fails, the _init() function must free any global resources allocated. _init() must call scsi_hba_fini(9F) before returning.

The following example uses a global mutex to show how to allocate data that is global to all instances of a driver. The code declares global mutex and soft-state structure information. The global mutex and soft state are initialized during _init().

_fini() Entry Point (SCSI HBA Drivers)

The _fini(9E) function is called when the system is about to try to unload the SCSI HBA driver. The _fini() function must call mod_remove(9F) to determine whether the driver can be unloaded. If mod_remove() returns 0, the module can be unloaded. The HBA driver must deallocate any global resources allocated in _init(9E). The HBA driver must also call scsi_hba_fini(9F).

_fini() must return the value returned by mod_remove().

The HBA driver must not free any resources or call scsi_hba_fini(9F) unless mod_remove(9F) returns 0.

Example 18–1 shows module initialization for SCSI HBA.

Example 18–1 Module Initialization for SCSI HBA

static struct dev_ops isp_dev_ops = {
    DEVO_REV,       /* devo_rev */
    0,              /* refcnt  */
    isp_getinfo,    /* getinfo */
    nulldev,        /* probe */
    isp_attach,     /* attach */
    isp_detach,     /* detach */
    nodev,          /* reset */
    NULL,           /* driver operations */
    NULL,           /* bus operations */
    isp_power,      /* power management */
};

/*
 * Local static data
 */
static kmutex_t      isp_global_mutex;
static void          *isp_state;

int
_init(void)
{
    int     err;
    
    if ((err = ddi_soft_state_init(&isp_state,
        sizeof (struct isp), 0)) != 0) {
        return (err);
    }
    if ((err = scsi_hba_init(&modlinkage)) == 0) {
        mutex_init(&isp_global_mutex, "isp global mutex",
        MUTEX_DRIVER, NULL);
        if ((err = mod_install(&modlinkage)) != 0) {
            mutex_destroy(&isp_global_mutex);
            scsi_hba_fini(&modlinkage);
            ddi_soft_state_fini(&isp_state);    
        }
    }
    return (err);
}

int
_fini(void)
{
    int     err;
    
    if ((err = mod_remove(&modlinkage)) == 0) {
        mutex_destroy(&isp_global_mutex);
        scsi_hba_fini(&modlinkage);
        ddi_soft_state_fini(&isp_state);
    }
    return (err);
}