2 * This file has been modified for the cdrkit suite.
4 * The behaviour and appearence of the program code below can differ to a major
5 * extent from the version distributed by the original author(s).
7 * For details, see Changelog file distributed with the cdrkit package. If you
8 * received this file from another source then ask the distributing person for
9 * a log of modifications.
13 /* pg.h (c) 1998 Grant R. Guenther <grant@torque.net>
14 Under the terms of the GNU public license
17 pg.h defines the user interface to the generic ATAPI packet
18 command driver for parallel port ATAPI devices (pg). The
19 driver is loosely modelled after the generic SCSI driver, sg,
20 although the actual interface is different.
22 The pg driver provides a simple character device interface for
23 sending ATAPI commands to a device. With the exception of the
24 ATAPI reset operation, all operations are performed by a pair
25 of read and write operations to the appropriate /dev/pgN device.
26 A write operation delivers a command and any outbound data in
27 a single buffer. Normally, the write will succeed unless the
28 device is offline or malfunctioning, or there is already another
29 command pending. If the write succeeds, it should be followed
30 immediately by a read operation, to obtain any returned data and
31 status information. A read will fail if there is no operation
34 As a special case, the device can be reset with a write operation,
35 and in this case, no following read is expected, or permitted.
37 There are no ioctl() operations. Any single operation
38 may transfer at most PG_MAX_DATA bytes. Note that the driver must
39 copy the data through an internal buffer. In keeping with all
40 current ATAPI devices, command packets are assumed to be exactly
43 To permit future changes to this interface, the headers in the
44 read and write buffers contain a single character "magic" flag.
45 Currently this flag must be the character "P".
51 #define PG_COMMAND 'C'
53 #define PG_MAX_DATA 32768
57 char magic; /* == PG_MAGIC */
58 char func; /* PG_RESET or PG_COMMAND */
59 int dlen; /* number of bytes expected to transfer */
60 int timeout; /* number of seconds before timeout */
61 char packet[12]; /* packet command */
67 char magic; /* == PG_MAGIC */
68 char scsi; /* "scsi" status == sense key */
69 int dlen; /* size of device transfer request */
70 int duration; /* time in seconds command took */
71 char pad[12]; /* not used */