Tribblix: manual page: detach.9e

DETACH(9E) Driver Entry Points DETACH(9E)

NAME

detach - detach or suspend a device

SYNOPSIS

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

int prefixdetach(dev_info_t * dip, ddi_detach_cmd_t cmd);

INTERFACE LEVEL

illumos DDI specific (illumos 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
unregister 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
quiescent. It will be issued only to devices which have a reg
property or which export a pm-hardware-state property with the value
needs-suspend-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(4)) 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 successfully 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