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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 License4 5 6 pg.h defines the user interface to the generic ATAPI packet7 command driver for parallel port ATAPI devices (pg). The8 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 for12 sending ATAPI commands to a device. With the exception of the13 ATAPI reset operation, all operations are performed by a pair14 of read and write operations to the appropriate /dev/pgN device.15 A write operation delivers a command and any outbound data in16 a single buffer. Normally, the write will succeed unless the17 device is offline or malfunctioning, or there is already another18 command pending. If the write succeeds, it should be followed19 immediately by a read operation, to obtain any returned data and20 status information. A read will fail if there is no operation21 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 operation27 may transfer at most PG_MAX_DATA bytes. Note that the driver must28 copy the data through an internal buffer. In keeping with all29 current ATAPI devices, command packets are assumed to be exactly30 12 bytes in length.31 32 To permit future changes to this interface, the headers in the33 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_H39#define _UAPI_LINUX_PG_H40 41#define PG_MAGIC 'P'42#define PG_RESET 'Z'43#define PG_COMMAND 'C'44 45#define PG_MAX_DATA 3276846 47struct 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 57struct 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