bpp(7D)
NAME
bpp - bi-directional parallel port driver
SYNOPSIS
SUNW,bpp@slot,offset:bppn
DESCRIPTION
The bpp driver provides a general-purpose bi-directional
interface to parallel devices. It supports a variety of out-
put (printer) and input (scanner) devices, using programm-
able timing relationships between the various handshake sig-
nals.
APPLICATION PROGRAMMING INTERFACE
The bpp driver is an exclusive-use device. If the device
has already been opened, subsequent opens fail with EBUSY.
Default Operation
Each time the bpp device is opened, the default configura-
tion is BPP_ACK_BUSY_HS for read handshake, BPP_ACK_HS for
write handshake, 1 microsecond for all setup times and
strobe widths, and 60 seconds for both timeouts. This confi-
guration (in the write mode) drives many common personal
computer parallel printers with Centronics-type interfaces.
The application should use the BPPIOC_SETPARMS ioctl
request to configure the bpp for the particular device which
is attached, if necessary.
Write Operation
If a failure or error condition occurs during a write(2),
the number of bytes successfully written is returned (short
write). Note that errno will not be set. The contents of
certain status bits will be captured at the time of the
error, and can be retrieved by the application program,
using the BPPIOC_GETERR ioctl request. Subsequent write(2)
calls may fail with the system error ENXIO if the error
condition is not rectified. The captured status information
will be overwritten each time an attempted transfer or a
BPPIOC_TESTIO ioctl request occurs.
Read Operations
If a failure or error condition occurs during a read(2), the
number of bytes successfully read is returned (short read).
Note that errno will not be set. The contents of certain
status bits will be captured at the time of the error, and
can be retrieved by the application, using the BPPIOC_GETERR
ioctl request. Subsequent read(2) calls may fail with ENXIO
if the error condition is not rectified. The captured regis-
ter information will be overwritten each time an attempted
transfer or a BPPIOC_TESTIO ioctl request.
If the read_handshake element of the bpp_transfer_parms
structure (see below) is set to BPP_CLEAR_MEM or
BPP_SET_MEM, zeroes or ones, respectively, are written into
the user buffer.
Read/Write Operation
When the driver is opened for reading and writing, it is
assumed that scanning will take place, as scanners are the
only devices supported by this mode. Most scanners require
that the SLCT_IN or AFX pin be set to tell the scanner the
direction of the transfer. The AFX line is set when the
read_handshake element of the bpp_transfer_parms structure
is set to BPP_HSCAN_HS, otherwise the SLCT_IN pin is set.
Normally, scanning starts by writing a command to the
scanner, at which time the pin is set. When the scan data
is read back, the pin is reset.
IOCTLS
The following ioctl requests are supported:
BPPIOC_SETPARMS
Set transfer parameters.
The argument is a pointer to a bpp_transfer_parms
structure. See below for a description of the elements
of this structure. If a parameter is out of range,
EINVAL is returned.
BPPIOC_GETPARMS
Get current transfer parameters.
The argument is a pointer to a bpp_transfer_parms
structure. See below for a description of the elements
of this structure. If no parameters have been config-
ured since the device was opened, the contents of the
structure will be the default conditions of the param-
eters (see Default Operation above).
BPPIOC_SETOUTPINS
Set output pin values.
The argument is a pointer to a bpp_pins structure.
See below for a description of the elements of this
structure. If a parameter is out of range, EINVAL is
returned.
BPPIOC_GETOUTPINS
Read output pin values. The argument is a pointer to a
bpp_pins structure. See below for a description of the
elements of this structure.
BPPIOC_GETERR
Get last error status.
The argument is a pointer to a bpp_error_status struc-
ture. See below for a description of the elements of
this structure. This structure indicates the status of
all the appropriate
status bits at the time of the most recent error con-
dition during a read(2) or write(2) call, or the
status of the bits at the most recent
BPPIOC_TESTIO ioctl request. Note: The bits in the
pin_status element indicate whether the associated pin
is active, not the actual polarity. The application
can check transfer readiness without attempting
another transfer using the BPPIOC_TESTIO ioctl.
Note: The timeout_occurred and bus_error fields will
never be set by the BPPIOC_TESTIO ioctl, only by an
actual failed transfer.
BPPIOC_TESTIO
Test transfer readiness.
This command checks to see if a read or write transfer
would succeed based on pin status, opened mode, and
handshake selected. If a handshake would succeed, 0
is returned. If a transfer would fail, -1 is
returned, and errno is set to EIO, and the error
status information is captured. The captured status
can be retrieved using the BPPIOC_GETERR ioctl call.
Note that the timeout_occurred and bus_error fields
will never be set by this ioctl.
Transfer Parameters Structure
This structure is defined in <sys/bpp_io.h>.
struct bpp_transfer_parms {
enum handshake_t
read_handshake; /* parallel port read handshake mode */
int read_setup_time; /* DSS register - in nanoseconds */
int read_strobe_width; /* DSW register - in nanoseconds */
int read_timeout; /*
* wait this many seconds
* before aborting a transfer
*/
enum handshake_t
write_handshake; /* parallel port write handshake mode */
int write_setup_time; /* DSS register - in nanoseconds */
int write_strobe_width; /* DSW register - in nanoseconds */
int write_timeout; /*
* wait this many seconds
* before aborting a transfer
*/
};
/* Values for read_handshake and write_handshake fields */
enum handshake_t {
BPP_NO_HS, /* no handshake pins */
BPP_ACK_HS, /* handshake controlled by ACK line */
BPP_BUSY_HS, /* handshake controlled by BSY line */
BPP_ACK_BUSY_HS, /*
* handshake controlled by ACK and BSY lines
* read_handshake only!
*/
BPP_XSCAN_HS, /* xerox scanner mode,
* read_handshake only!
*/
BPP_HSCAN_HS, /*
* HP scanjet scanner mode
* read_handshake only!
*/
BPP_CLEAR_MEM, /* write 0's to memory,
* read_handshake only!
*/
BPP_SET_MEM, /* write 1's to memory,
* read_handshake only!
*/
/* The following handshakes are RESERVED. Do not use. */
BPP_VPRINT_HS, /* valid only in read/write mode */
BPP_VPLOT_HS /* valid only in read/write mode */
};
The read_setup_time field controls the time between dstrb
falling edge to bsy rising edge if the read_handshake field
is set to BPP_NO_HS or BPP_ACK_HS. It controls the time
between dstrb falling edge to ack rising edge if the
read_handshake field is set to BPP_ACK_HS or
BPP_ACK_BUSY_HS. It controls the time between ack falling
edge to dstrb rising edge if the read_handshake field is set
to BPP_XSCAN_HS.
The read_strobe_width field controls the time between ack
rising edge and ack falling edge if the read_handshake field
is set to BPP_NO_HS or BPP_ACK_BUSY_HS. It controls the time
between dstrb rising edge to dstrb falling edge if the
read_handshake field is set to BPP_XSCAN_HS.
The values allowed for the write_handshake field are dupli-
cates of the definitions for the read_handshake field. Note
that some of these handshake definitions are only valid in
one mode or the other.
The write_setup_time field controls the time between data
valid to dstrb rising edge for all values of the
write_handshake field.
The write_strobe_width field controls the time between
dstrb rising edge and dstrb falling edge if the
write_handshake field is not set to BPP_VPRINT_HS or
BPP_VPLOT_HS. It controls the minimum time between dstrb
rising edge to dstrb falling edge if the write_handshake
field is set to BPP_VPRINT_HS or BPP_VPLOT_HS.
Transfer Pins Structure
This structure is defined in <sys/bpp_io.h>.
struct bpp_pins {
uchar_t output_reg_pins; /* pins in P_OR register */
uchar_t input_reg_pins; /* pins in P_IR register */
};
/* Values for output_reg_pins field */
#define BPP_SLCTIN_PIN 0x01 /* Select in pin */
#define BPP_AFX_PIN 0x02 /* Auto feed pin */
#define BPP_INIT_PIN 0x04 /* Initialize pin */
#define BPP_V1_PIN 0x08 /* reserved pin 1 */
#define BPP_V2_PI 0x10 /* reserved pin 2 */
#define BPP_V3_PIN 0x20 /* reserved pin 3 */
#define BPP_ERR_PIN 0x01 /* Error pin */
#define BPP_SLCT_PIN 0x02 /* Select pin */
#define BPP_PE_PIN 0x04 /* Paper empty pin */
Error Pins Structure
This structure is defined in the include file
<sys/bpp_io.h>.
struct bpp_error_status {
char timeout_occurred; /* 1 if a timeout occurred */
char bus_error; /* 1 if an SBus bus error */
uchar_t pin_status; /*
* status of pins which could
* cause an error
*/
};
/* Values for pin_status field */
#define BPP_ERR_ERR 0x01 /* Error pin active */
#define BPP_SLCT_ERR 0x02 /* Select pin active */
#define BPP_PE_ERR 0x04 /* Paper empty pin active */
#define BPP_SLCTIN_ERR 0x10 /* Select in pin active */
#define BPP_BUSY_ERR 0x40 /* Busy pin active */
ERRORS
EBADF The device is opened for write-only access and a read
is attempted, or the device is opened for read-only
access and a write is attempted.
EBUSY The device has been opened and another open is
attempted. An attempt has been made to unload the
driver while one of the units is open.
EINVAL
A BPPIOC_SETPARMS ioctl is attempted with an out of
range value in the bpp_transfer_parms structure. A
BPPIOC_SETOUTPINS ioctl is attempted with an invalid
value in the pins structure. An ioctl is attempted
with an invalid value in the command argument. An
invalid command argument is received during
modload(1M) or modunload(1M).
EIO The driver encountered an SBus bus error when attempt-
ing an access.
A read or write does not complete properly, due to a
peripheral error or a transfer timeout.
A BPPIOC_TESTIO ioctl call is attempted while a condi-
tion exists which would prevent a transfer (such as a
peripheral error).
ENXIO The driver has received an open request for a unit
for which the attach failed. The driver has received a
read or write request for a unit number greater than
the number of units available. The driver has received
a write request for a unit which has an active peri-
pheral error.
FILES
/dev/bppn
bi-directional parallel port devices
SEE ALSO
ioctl(2), read(2), write(2), sbus(4)
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