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67 lines
2.4 KiB
67 lines
2.4 KiB
/* SPDX-License-Identifier: GPL-1.0+ WITH Linux-syscall-note */ |
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/* pg.h (c) 1998 Grant R. Guenther <[email protected]> |
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Under the terms of the GNU General Public License |
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pg.h defines the user interface to the generic ATAPI packet |
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command driver for parallel port ATAPI devices (pg). The |
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driver is loosely modelled after the generic SCSI driver, sg, |
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although the actual interface is different. |
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The pg driver provides a simple character device interface for |
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sending ATAPI commands to a device. With the exception of the |
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ATAPI reset operation, all operations are performed by a pair |
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of read and write operations to the appropriate /dev/pgN device. |
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A write operation delivers a command and any outbound data in |
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a single buffer. Normally, the write will succeed unless the |
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device is offline or malfunctioning, or there is already another |
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command pending. If the write succeeds, it should be followed |
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immediately by a read operation, to obtain any returned data and |
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status information. A read will fail if there is no operation |
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in progress. |
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As a special case, the device can be reset with a write operation, |
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and in this case, no following read is expected, or permitted. |
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There are no ioctl() operations. Any single operation |
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may transfer at most PG_MAX_DATA bytes. Note that the driver must |
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copy the data through an internal buffer. In keeping with all |
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current ATAPI devices, command packets are assumed to be exactly |
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12 bytes in length. |
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To permit future changes to this interface, the headers in the |
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read and write buffers contain a single character "magic" flag. |
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Currently this flag must be the character "P". |
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*/ |
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#ifndef _UAPI_LINUX_PG_H |
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#define _UAPI_LINUX_PG_H |
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#define PG_MAGIC 'P' |
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#define PG_RESET 'Z' |
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#define PG_COMMAND 'C' |
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#define PG_MAX_DATA 32768 |
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struct pg_write_hdr { |
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char magic; /* == PG_MAGIC */ |
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char func; /* PG_RESET or PG_COMMAND */ |
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int dlen; /* number of bytes expected to transfer */ |
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int timeout; /* number of seconds before timeout */ |
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char packet[12]; /* packet command */ |
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}; |
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struct pg_read_hdr { |
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char magic; /* == PG_MAGIC */ |
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char scsi; /* "scsi" status == sense key */ |
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int dlen; /* size of device transfer request */ |
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int duration; /* time in seconds command took */ |
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char pad[12]; /* not used */ |
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}; |
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#endif /* _UAPI_LINUX_PG_H */
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