parport: Add comments for parport_register_dev_model()

	kfree(par_dev);

}

/**

 *	parport_register_dev_model - register a device on a parallel port

 *	@port: port to which the device is attached

 *	@name: a name to refer to the device

 *	@par_dev_cb: struct containing callbacks

 *	@id: device number to be given to the device

 *

 *	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 struct pardev_cb contains pointer to callbacks. preemption

 *	callback function, @preempt, is called when this device driver

 *	has claimed access to the port but another device driver wants

 *	to use it.  It is given, @private, 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, @preempt can be %NULL.

 *

 *	The wake-up ("kick") callback function, @wakeup, 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, @wakeup 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.

 **/

struct pardevice *

parport_register_dev_model(struct parport *port, const char *name,

			   const struct pardev_cb *par_dev_cb, int id)

			  void (*irq_func)(void *), 

			  int flags, void *handle);

/*

 * parport_register_dev_model declares that a device is connected to a

 * port, and tells the kernel all it needs to know.

 */

struct pardevice *

parport_register_dev_model(struct parport *port, const char *name,

			   const struct pardev_cb *par_dev_cb, int cnt);