parport_remove_port(9) [centos man page]

PARPORT_REMOVE_PORT(9)					       Parallel Port Devices					    PARPORT_REMOVE_PORT(9)

NAME

       parport_remove_port - deregister a parallel port

SYNOPSIS

       void parport_remove_port(struct parport * port);

ARGUMENTS

       port
	   parallel port to deregister

DESCRIPTION

       When a parallel port driver is forcibly unloaded, or a parallel port becomes inaccessible, the port driver must call this function in order
       to deal with device drivers that still want to use it.

       The parport structure associated with the port has its operations structure replaced with one containing 'null' operations that return
       errors or just don't do anything.

       Any drivers that have registered themselves using parport_register_driver are notified that the port is no longer accessible by having
       their detach routines called with port as the parameter.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						    PARPORT_REMOVE_PORT(9)

PARPORT_REGISTER_DEV(9) 				       Parallel Port Devices					   PARPORT_REGISTER_DEV(9)

NAME

       parport_register_device - register a device on a parallel port

SYNOPSIS

       struct pardevice * parport_register_device(struct parport * port, const char * name, int (*pf) (void *), void (*kf) (void *),
						  void (*irq_func) (void *), int flags, void * handle);

ARGUMENTS

       port
	   port to which the device is attached

       name
	   a name to refer to the device

       pf
	   preemption callback

       kf
	   kick callback (wake-up)

       irq_func
	   interrupt handler

       flags
	   registration flags

       handle
	   data for callback functions

DESCRIPTION

       This function, called by parallel port device drivers, declares that a device is connected to a port, and tells the system all it needs to
       know.

       The name is allocated by the caller and must not be deallocated until the caller calls parport_unregister_device for that device.

       The preemption callback function, pf, is called when this device driver has claimed access to the port but another device driver wants to
       use it. It is given handle as its parameter, and should return zero if it is willing for the system to release the port to another driver
       on its behalf. If it wants to keep control of the port it should return non-zero, and no action will be taken. It is good manners for the
       driver to try to release the port at the earliest opportunity after its preemption callback rejects a preemption attempt. Note that if a
       preemption callback is happy for preemption to go ahead, there is no need to release the port; it is done automatically. This function may
       not block, as it may be called from interrupt context. If the device driver does not support preemption, pf can be NULL.

       The wake-up ("kick") callback function, kf, is called when the port is available to be claimed for exclusive access; that is, parport_claim
       is guaranteed to succeed when called from inside the wake-up callback function. If the driver wants to claim the port it should do so;
       otherwise, it need not take any action. This function may not block, as it may be called from interrupt context. If the device driver does
       not want to be explicitly invited to claim the port in this way, kf can be NULL.

       The interrupt handler, irq_func, is called when an interrupt arrives from the parallel port. Note that if a device driver wants to use
       interrupts it should use parport_enable_irq, and can also check the irq member of the parport structure representing the port.

       The parallel port (lowlevel) driver is the one that has called request_irq and whose interrupt handler is called first. This handler does
       whatever needs to be done to the hardware to acknowledge the interrupt (for PC-style ports there is nothing special to be done). It then
       tells the IEEE 1284 code about the interrupt, which may involve reacting to an IEEE 1284 event depending on the current IEEE 1284 phase.
       After this, it calls irq_func. Needless to say, irq_func will be called from interrupt context, and may not block.

       The PARPORT_DEV_EXCL flag is for preventing port sharing, and so should only be used when sharing the port with other device drivers is
       impossible and would lead to incorrect behaviour. Use it sparingly! Normally, flags will be zero.

       This function returns a pointer to a structure that represents the device on the port, or NULL if there is not enough memory to allocate
       space for that structure.

COPYRIGHT

Kernel Hackers Manual 3.10					     June 2014						   PARPORT_REGISTER_DEV(9)