attach()

	int attach(dev_info_t *dip, ddi_attach_cmd_t cmd);

When a device that has been suspended is needed again, its power(9E) entry point is called to restore the power level of component 0 (entire device) to its normal power. The driver's attach(9E) entry point is then called with an attach command value of DDI_PM_RESUME to restore the device hardware state saved in the detach(9E) routine and unblock any pending operations. Example 8-3 shows an attach(9E) routine with DDI_PM_RESUME implemented.

Example 8-3 attach(9E) Showing the Use of DDI_PM_RESUME

int
xxattach(devinfo_t *dip, ddi_attach_cmd_t cmd)
{
 	struct xxstate *xsp;
 	int	instance;

 	instance = ddi_get_instance(dip);
 	xsp = ddi_get_soft_state(statep, instance);

 	switch (cmd) {
 	case DDI_ATTACH:
	   	see chapter 5, Autoconfiguration for discussion

 	case DDI_RESUME:
	   	see Example 8-5 for DDI_RESUME implementation

 	case DDI_PM_RESUME:
		   /*
		    * We won't be DDI_PM_RESUMEd while DDI_SUSPENDed
		    */
	   	 mutex_enter(&xsp->mu);
	   	 Restore device register contents from xsp->xx_device_state
		
	      	this section is optional, only needed if the driver maintains a running timeout
	   	 /* restart timeouts */
	   	 xsp->xx_timeout_id = timeout({...});
		
	   	 xsp->xx_pm_suspended = 0;	/* allow new operations */
	   	 cv_broadcast(&xsp->cv);
	   	 mutex_exit(&xsp->mu);
	   	 return(DDI_SUCCESS);

 	default:
	   	return(DDI_FAILURE);
 	}
}