1PARPORT_REGISTER_DEV(9) Parallel Port Devices PARPORT_REGISTER_DEV(9)
2
6 parport_register_device - register a device on a parallel port
7
9 struct pardevice * parport_register_device(struct parport * port,
10 const char * name,
11 int (*pf) (void *),
12 void (*kf) (void *),
13 void (*irq_func) (void *),
14 int flags, void * handle);
15
17 port
18 port to which the device is attached
19 name
21 a name to refer to the device
22 pf
24 preemption callback
25 kf
27 kick callback (wake-up)
28 irq_func
30 interrupt handler
31 flags
33 registration flags
34 handle
36 data for callback functions
37
39 This function, called by parallel port device drivers, declares that a
40 device is connected to a port, and tells the system all it needs to
41 know.
42 The name is allocated by the caller and must not be deallocated until
44 the caller calls parport_unregister_device for that device.
45 The preemption callback function, pf, is called when this device driver
47 has claimed access to the port but another device driver wants to use
48 it. It is given handle as its parameter, and should return zero if it
49 is willing for the system to release the port to another driver on its
50 behalf. If it wants to keep control of the port it should return
51 non-zero, and no action will be taken. It is good manners for the
52 driver to try to release the port at the earliest opportunity after its
53 preemption callback rejects a preemption attempt. Note that if a
54 preemption callback is happy for preemption to go ahead, there is no
55 need to release the port; it is done automatically. This function may
56 not block, as it may be called from interrupt context. If the device
57 driver does not support preemption, pf can be NULL.
58 The wake-up (“kick”) callback function, kf, is called when the port is
60 available to be claimed for exclusive access; that is, parport_claim is
61 guaranteed to succeed when called from inside the wake-up callback
62 function. If the driver wants to claim the port it should do so;
63 otherwise, it need not take any action. This function may not block, as
64 it may be called from interrupt context. If the device driver does not
65 want to be explicitly invited to claim the port in this way, kf can be
66 NULL.
67 The interrupt handler, irq_func, is called when an interrupt arrives
69 from the parallel port. Note that if a device driver wants to use
70 interrupts it should use parport_enable_irq, and can also check the irq
71 member of the parport structure representing the port.
72 The parallel port (lowlevel) driver is the one that has called
74 request_irq and whose interrupt handler is called first. This handler
75 does whatever needs to be done to the hardware to acknowledge the
76 interrupt (for PC-style ports there is nothing special to be done). It
77 then tells the IEEE 1284 code about the interrupt, which may involve
78 reacting to an IEEE 1284 event depending on the current IEEE 1284
79 phase. After this, it calls irq_func. Needless to say, irq_func will be
80 called from interrupt context, and may not block.
81 The PARPORT_DEV_EXCL flag is for preventing port sharing, and so should
83 only be used when sharing the port with other device drivers is
84 impossible and would lead to incorrect behaviour. Use it sparingly!
85 Normally, flags will be zero.
86 This function returns a pointer to a structure that represents the
88 device on the port, or NULL if there is not enough memory to allocate
89 space for that structure.
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92Kernel Hackers Manual 3.10 June 2019 PARPORT_REGISTER_DEV(9)