detach(9E)							Driver Entry Points							detach(9E)

NAME

       detach - detach or suspend a device

SYNOPSIS

       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int prefix detach(dev_info_t dip, ddi_detach_cmd_t cmd);

INTERFACE LEVEL

       Solaris DDI specific (Solaris DDI)

PARAMETERS

       dip    A pointer to the device's dev_info structure.

       cmd    Type of detach; the driver should return DDI_FAILURE if any value other than DDI_DETACH or DDI_SUSPEND is passed to it.

DESCRIPTION

       The detach() function complements the attach(9E) routine.

   DDI_DETACH
       If cmd is set to DDI_DETACH, detach() is used to remove the state associated with a given instance of a device node prior to the removal of
       that instance from the system.

       The detach() function will be called once for each instance of the device for which there has been a successful attach(), once there are no
       longer any opens on the device. An attached instance of a driver can be successfully detached only once. The detach() function should clean
       up any per instance data initialized in attach(9E) and call kmem_free(9F) to free any heap allocations. For information on how to  unregis-
       ter interrupt handlers, see ddi_add_intr(9F). This should also include putting the underlying device into a quiescent state so that it will
       not generate interrupts.

       Drivers that set up timeout(9F) routines should ensure that they are cancelled before returning DDI_SUCCESS from detach().

       If detach() determines a particular instance of the device cannot be removed when requested because of some exceptional condition, detach()
       must  return  DDI_FAILURE,  which  prevents  the  particular  device instance from being detached. This also prevents the driver from being
       unloaded. A driver instance failing the detach must ensure that no per instance data or state is modified or freed  that  would	compromise
       the system or subsequent driver operation.

       The  system  guarantees that the function will only be called for a particular dev_info node after (and not concurrently with) a successful
       attach(9E) of that device. The system also guarantees that detach() will only be called when there are no outstanding open(9E) calls on the
       device.

   DDI_SUSPEND
       The  DDI_SUSPEND  cmd  is issued when the entire system is being suspended and power removed from it or when the system must be made quies-
       cent. It will be issued only to devices which have a reg property or which export a pm-hardware-state property with  the  value	needs-sus-
       pend-resume.

       If  cmd is set to DDI_SUSPEND, detach() is used to suspend all activity of a device before power is (possibly) removed from the device. The
       steps associated with suspension must include putting the underlying device into a quiescent state so that it will not generate	interrupts
       or  modify or access memory. Once quiescence has been obtained, detach() can be called with outstanding open(9E) requests. It must save the
       hardware state of the device to memory and block incoming or existing requests until attach() is called with DDI_RESUME.

       If the device is used to store file systems, then after DDI_SUSPEND is issued, the device should still  honor  dump(9E)	requests  as  this
       entry point may be used by suspend-resume operation (see cpr(7)) to save state file. It must do this, however, without disturbing the saved
       hardware state of the device.

       If the device driver uses automatic device Power Management interfaces (driver exports pm-components(9P) property), it might need  to  call
       pm_raise_power(9F) if the current power level is lower than required to complete the dump(9E) request.

       Before  returning  successfully	from a call to detach() with a command of DDI_SUSPEND, the driver must cancel any outstanding timeouts and
       make any driver threads quiescent.

       If DDI_FAILURE is returned for the DDI_SUSPEND cmd, either the operation to suspend the system or to make it quiescent will be aborted.

RETURN VALUES

       DDI_SUCCESS    For DDI_DETACH, the state associated with the given device was successfully removed. For DDI_SUSPEND, the  driver  was  suc-
		      cessfully suspended.

       DDI_FAILURE    The operation failed or the request was not understood. The associated state is unchanged.

CONTEXT

       This function is called from user context only.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+

SEE ALSO

       cpr(7),	 pm(7D),   pm(9P),   pm-components(9P),   attach(9E),  dump(9E),  open(9E),  power(9E),  ddi_add_intr(9F),  ddi_dev_is_needed(9F),
       ddi_map_regs(9F), kmem_free(9F), pm_raise_power(9F), timeout(9F)

       Writing Device Drivers

SunOS 5.11							    7 Dec 2003								detach(9E)