| /* 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". |
| |
| */ |
| |
| #ifndef _UAPI_LINUX_PG_H |
| #define _UAPI_LINUX_PG_H |
| |
| #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 */ |
| |
| }; |
| |
| #endif /* _UAPI_LINUX_PG_H */ |