PARPORT_REGISTER_DEV(9) Parallel Port Devices PARPORT_REGISTER_DEV(9)NAMEparport_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.
COPYRIGHTKernel Hackers Manual 2.6. November 2013 PARPORT_REGISTER_DEV(9)
