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34 .Nd "user-space interface to ppbus parallel 'geek' port"
38 Minor numbering: Unit numbers correspond directly to ppbus numbers.
42 driver provides a convenient means for user applications to manipulate the
43 state of the parallel port, enabling easy low-speed I/O operations without
44 the security problems inherent with the use of the
47 .Sh PROGRAMMING INTERFACE
48 .In dev/misc/ppi/ppi.h
49 .In bus/ppbus/ppbconf.h
53 interface is performed using
55 calls. Each command takes a single
57 argument, transferring one byte of data. The following commands are
59 .Bl -tag -width indent
60 .It Dv PPIGDATA , PPISDATA
61 Get and set the contents of the data register.
62 .It Dv PPIGSTATUS , PPISSTATUS
63 Get and set the contents of the status register.
64 .It Dv PPIGCTRL , PPISCTRL
65 Get and set the contents of the control register.
66 The following defines correspond to bits in this register. Setting
67 a bit in the control register drives the corresponding output low.
68 .Bl -tag -width indent -compact
75 .It Dv PPIGEPPA , PPISEPPA
76 Get and set the address bits of the EPP control register.
77 .It Dv PPIGEPPD , PPISEPPD
78 Get and set the data bits of the EPP control register.
79 .It Dv PPIGECR , PPISECR
80 Get and set the contents of the ECP control register.
81 .It Dv PPIGFIFO , PPISFIFO
82 Read and write the ECP FIFO (8-bit operations only).
85 To present the value 0x5a to the data port, drive STROBE low and then high
86 again, the following code fragment can be used:
93 ioctl(fd, PPISDATA, &val);
94 ioctl(fd, PPIGCTRL, &val);
96 ioctl(fd, PPISCTRL, &val);
98 ioctl(fd, PPISCTRL, &val);
102 The inverse sense of signals is confusing.
106 interface is slow, and there is no way (yet) to chain multiple operations together.