Provided by:
kernel-doc-2.4.27_2.4.27-12_all 
NAME
pm_send - send request to a single device
SYNOPSIS
int pm_send (struct pm_dev *dev, pm_request_t rqst, void *data);
ARGUMENTS
dev device to send to
rqst power management request
data data for the callback
DESCRIPTION
Issue a power management request to a given device. The PM_SUSPEND and
PM_RESUME events are handled specially. The data field must hold the
intended next state. No call is made if the state matches.
BUGS
what stops two power management requests occuring in parallel and
conflicting.
WARNING
Calling pm_send directly is not generally recommended, in paticular
there is no locking against the pm_dev going away. The caller must
maintain all needed locking or have ’inside knowledge’ on the safety.
Also remember that this function is not locked against pm_unregister.
This means that you must handle SMP races on callback execution and
unload yourself.