65 lines
2.3 KiB
C
65 lines
2.3 KiB
C
|
/* SPDX-License-Identifier: GPL-1.0+ WITH Linux-syscall-note */
|
||
|
|
/* pg.h (c) 1998 Grant R. Guenther <grant@torque.net>
|
||
|
|
Under the terms of the GNU General Public License
|
||
|
|
|
||
|
|
|
||
|
|
pg.h defines the user interface to the generic ATAPI packet
|
||
|
|
command driver for parallel port ATAPI devices (pg). The
|
||
|
|
driver is loosely modelled after the generic SCSI driver, sg,
|
||
|
|
although the actual interface is different.
|
||
|
|
|
||
|
|
The pg driver provides a simple character device interface for
|
||
|
|
sending ATAPI commands to a device. With the exception of the
|
||
|
|
ATAPI reset operation, all operations are performed by a pair
|
||
|
|
of read and write operations to the appropriate /dev/pgN device.
|
||
|
|
A write operation delivers a command and any outbound data in
|
||
|
|
a single buffer. Normally, the write will succeed unless the
|
||
|
|
device is offline or malfunctioning, or there is already another
|
||
|
|
command pending. If the write succeeds, it should be followed
|
||
|
|
immediately by a read operation, to obtain any returned data and
|
||
|
|
status information. A read will fail if there is no operation
|
||
|
|
in progress.
|
||
|
|
|
||
|
|
As a special case, the device can be reset with a write operation,
|
||
|
|
and in this case, no following read is expected, or permitted.
|
||
|
|
|
||
|
|
There are no ioctl() operations. Any single operation
|
||
|
|
may transfer at most PG_MAX_DATA bytes. Note that the driver must
|
||
|
|
copy the data through an internal buffer. In keeping with all
|
||
|
|
current ATAPI devices, command packets are assumed to be exactly
|
||
|
|
12 bytes in length.
|
||
|
|
|
||
|
|
To permit future changes to this interface, the headers in the
|
||
|
|
read and write buffers contain a single character "magic" flag.
|
||
|
|
Currently this flag must be the character "P".
|
||
|
|
|
||
|
|
*/
|
||
|
|
|
||
|
|
#define PG_MAGIC 'P'
|
||
|
|
#define PG_RESET 'Z'
|
||
|
|
#define PG_COMMAND 'C'
|
||
|
|
|
||
|
|
#define PG_MAX_DATA 32768
|
||
|
|
|
||
|
|
struct pg_write_hdr {
|
||
|
|
|
||
|
|
char magic; /* == PG_MAGIC */
|
||
|
|
char func; /* PG_RESET or PG_COMMAND */
|
||
|
|
int dlen; /* number of bytes expected to transfer */
|
||
|
|
int timeout; /* number of seconds before timeout */
|
||
|
|
char packet[12]; /* packet command */
|
||
|
|
|
||
|
|
};
|
||
|
|
|
||
|
|
struct pg_read_hdr {
|
||
|
|
|
||
|
|
char magic; /* == PG_MAGIC */
|
||
|
|
char scsi; /* "scsi" status == sense key */
|
||
|
|
int dlen; /* size of device transfer request */
|
||
|
|
int duration; /* time in seconds command took */
|
||
|
|
char pad[12]; /* not used */
|
||
|
|
|
||
|
|
};
|
||
|
|
|
||
|
|
/* end of pg.h */
|