| parport_register_device(9) - phpMan
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 4.8. January 2017 PARPORT_REGISTER_DEV(9)
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