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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 |
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