1 /* SPDX-License-Identifier: GPL-1.0+ WITH Linux-syscall-note */
2 /* 	pg.h (c) 1998  Grant R. Guenther <grant@torque.net>
3  		       Under the terms of the GNU General Public License
4 
5 
6 	pg.h defines the user interface to the generic ATAPI packet
7         command driver for parallel port ATAPI devices (pg). The
8 	driver is loosely modelled after the generic SCSI driver, sg,
9 	although the actual interface is different.
10 
11 	The pg driver provides a simple character device interface for
12         sending ATAPI commands to a device.  With the exception of the
13 	ATAPI reset operation, all operations are performed by a pair
14         of read and write operations to the appropriate /dev/pgN device.
15 	A write operation delivers a command and any outbound data in
16         a single buffer.  Normally, the write will succeed unless the
17         device is offline or malfunctioning, or there is already another
18 	command pending.  If the write succeeds, it should be followed
19         immediately by a read operation, to obtain any returned data and
20         status information.  A read will fail if there is no operation
21         in progress.
22 
23 	As a special case, the device can be reset with a write operation,
24         and in this case, no following read is expected, or permitted.
25 
26 	There are no ioctl() operations.  Any single operation
27 	may transfer at most PG_MAX_DATA bytes.  Note that the driver must
28         copy the data through an internal buffer.  In keeping with all
29 	current ATAPI devices, command packets are assumed to be exactly
30 	12 bytes in length.
31 
32 	To permit future changes to this interface, the headers in the
33 	read and write buffers contain a single character "magic" flag.
34         Currently this flag must be the character "P".
35 
36 */
37 
38 #ifndef _UAPI_LINUX_PG_H
39 #define _UAPI_LINUX_PG_H
40 
41 #define PG_MAGIC	'P'
42 #define PG_RESET	'Z'
43 #define PG_COMMAND	'C'
44 
45 #define PG_MAX_DATA	32768
46 
47 struct pg_write_hdr {
48 
49 	char	magic;		/* == PG_MAGIC */
50 	char	func;		/* PG_RESET or PG_COMMAND */
51 	int     dlen;		/* number of bytes expected to transfer */
52 	int     timeout;	/* number of seconds before timeout */
53 	char	packet[12];	/* packet command */
54 
55 };
56 
57 struct pg_read_hdr {
58 
59 	char	magic;		/* == PG_MAGIC */
60 	char	scsi;		/* "scsi" status == sense key */
61 	int	dlen;		/* size of device transfer request */
62 	int     duration;	/* time in seconds command took */
63 	char    pad[12];	/* not used */
64 
65 };
66 
67 #endif /* _UAPI_LINUX_PG_H */
68