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CAM_CDBPARSE(3) FreeBSD Library Functions Manual CAM_CDBPARSE(3)
NAME
csio_build, csio_build_visit, csio_decode, csio_decode_visit,
buff_decode, buff_decode_visit, csio_encode, csio_encode_visit,
buff_encode_visit - CAM user library SCSI buffer parsing routines
LIBRARY
Common Access Method User Library (libcam, -lcam)
SYNOPSIS
#include <stdio.h>
#include <camlib.h>
int
csio_build(struct ccb_scsiio *csio, uint8_t *data_ptr,
uint32_t dxfer_len, uint32_t flags, int retry_count, int timeout,
const char *cmd_spec, ...);
int
csio_build_visit(struct ccb_scsiio *csio, uint8_t *data_ptr,
uint32_t dxfer_len, uint32_t flags, int retry_count, int timeout,
const char *cmd_spec, int (*arg_get)(void *hook, char *field_name),
void *gethook);
int
csio_decode(struct ccb_scsiio *csio, const char *fmt, ...);
int
csio_decode_visit(struct ccb_scsiio *csio, const char *fmt,
void (*arg_put)(void *hook, int letter, void *val, int count,
char *name), void *puthook);
int
buff_decode(uint8_t *buff, size_t len, const char *fmt, ...);
int
buff_decode_visit(uint8_t *buff, size_t len, const char *fmt,
void (*arg_put)(void *, int, void *, int, char *), void *puthook);
int
csio_encode(struct ccb_scsiio *csio, const char *fmt, ...);
int
csio_encode_visit(struct ccb_scsiio *csio, const char *fmt,
int (*arg_get)(void *hook, char *field_name), void *gethook);
int
buff_encode_visit(uint8_t *buff, size_t len, const char *fmt,
int (*arg_get)(void *hook, char *field_name), void *gethook);
DESCRIPTION
The CAM buffer/CDB encoding and decoding routines provide a relatively
easy migration path for userland SCSI applications written with the
similarly-named scsireq_* functions from the old FreeBSD SCSI layer.
These functions may be used in new applications, but users may find it
easier to use the various SCSI CCB building functions included with the
cam(3) library, e.g., cam_fill_csio(), scsi_start_stop(), and
determined by the flags argument.
data_ptr is the data buffer used during the SCSI data phase. If no data
is to be transferred for the SCSI command in question, this should be set
to NULL. If there is data to transfer for the command, this buffer must
be at least dxfer_len long.
flags are the flags defined in <cam/cam_ccb.h>:
/* Common CCB header */
/* CAM CCB flags */
typedef enum {
CAM_CDB_POINTER = 0x00000001,/* The CDB field is a pointer */
CAM_SCATTER_VALID = 0x00000010,/* Scatter/gather list is valid */
CAM_DIS_AUTOSENSE = 0x00000020,/* Disable autosense feature */
CAM_DIR_RESV = 0x00000000,/* Data direction (00:reserved) */
CAM_DIR_IN = 0x00000040,/* Data direction (01:DATA IN) */
CAM_DIR_OUT = 0x00000080,/* Data direction (10:DATA OUT) */
CAM_DIR_NONE = 0x000000C0,/* Data direction (11:no data) */
CAM_DIR_MASK = 0x000000C0,/* Data direction Mask */
CAM_DEV_QFRZDIS = 0x00000400,/* Disable DEV Q freezing */
CAM_DEV_QFREEZE = 0x00000800,/* Freeze DEV Q on execution */
CAM_HIGH_POWER = 0x00001000,/* Command takes a lot of power */
CAM_SENSE_PTR = 0x00002000,/* Sense data is a pointer */
CAM_SENSE_PHYS = 0x00004000,/* Sense pointer is physical addr*/
CAM_TAG_ACTION_VALID = 0x00008000,/* Use the tag action in this ccb*/
CAM_PASS_ERR_RECOVER = 0x00010000,/* Pass driver does err. recovery*/
CAM_DIS_DISCONNECT = 0x00020000,/* Disable disconnect */
CAM_SG_LIST_PHYS = 0x00040000,/* SG list has physical addrs. */
CAM_DATA_PHYS = 0x00200000,/* SG/Buffer data ptrs are phys. */
CAM_CDB_PHYS = 0x00400000,/* CDB pointer is physical */
/* Host target Mode flags */
CAM_SEND_SENSE = 0x08000000,/* Send sense data with status */
CAM_SEND_STATUS = 0x80000000,/* Send status after data phase */
} ccb_flags;
Multiple flags should be ORed together. Any of the CCB flags may be
used, although it is worth noting several important ones here:
CAM_DIR_IN This indicates that the operation in question is a
read operation. i.e., data is being read from the
SCSI device to the user-supplied buffer.
CAM_DIR_OUT This indicates that the operation is a write
operation. i.e., data is being written from the
user-supplied buffer to the device.
CAM_DIR_NONE This indicates that there is no data to be
transferred for this command.
CAM_DEV_QFRZDIS This flag disables device queue freezing as an
error recovery mechanism.
CAM_PASS_ERR_RECOVER This flag tells the pass(4) driver to enable error
recovery. The default is to not perform error
recovery, which means that the retry count will not
be honored without this flag, among other things.
The timeout tells the kernel how long to wait for the given command to
complete. If the timeout expires and the command has not completed, the
CCB will be returned from the kernel with an appropriate error status.
cmd_spec is a CDB format specifier used to build up the SCSI CDB. This
text string is made up of a list of field specifiers. Field specifiers
specify the value for each CDB field (including indicating that the value
be taken from the next argument in the variable argument list), the width
of the field in bits or bytes, and an optional name. White space is
ignored, and the pound sign ('#') introduces a comment that ends at the
end of the current line.
The optional name is the first part of a field specifier and is in curly
braces. The text in curly braces in this example are the names:
{PS} v:b1 {Reserved} 0:b1 {Page Code} v:b6 # Mode select page
This field specifier has two one bit fields and one six bit field. The
second one bit field is the constant value 0 and the first one bit field
and the six bit field are taken from the variable argument list. Multi
byte fields are swapped into the SCSI byte order in the CDB and white
space is ignored.
When the field is a hex value or the letter v, (e.g., 1A or v) then a
single byte value is copied to the next unused byte of the CDB. When the
letter v is used the next integer argument is taken from the variable
argument list and that value used.
A constant hex value followed by a field width specifier or the letter v
followed by a field width specifier (e.g., 3:4, 3:b4, 3:i3, v:i3)
specifies a field of a given bit or byte width. Either the constant
value or (for the V specifier) the next integer value from the variable
argument list is copied to the next unused bits or bytes of the CDB.
A decimal number or the letter b followed by a decimal number field width
indicates a bit field of that width. The bit fields are packed as
tightly as possible beginning with the high bit (so that it reads the
same as the SCSI spec), and a new byte of the CDB is started whenever a
byte fills completely or when an i field is encountered.
A field width specifier consisting of the letter i followed by either 1,
2, 3 or 4 indicates a 1, 2, 3 or 4 byte integral value that must be
swapped into SCSI byte order (MSB first).
For the v field specifier the next integer argument is taken from the
variable argument list and that value is used swapped into SCSI byte
order.
csio_build_visit() operates similarly to csio_build(), except that the
values to substitute for variable arguments in cmd_spec are retrieved via
the arg_get() function passed in to csio_build_visit() instead of via
stdarg(3). The arg_get() function takes two arguments:
gethook is passed into the arg_get() function at each invocation.
This enables the arg_get() function to keep some state in
between calls without using global or static variables.
field_name is the field name supplied in fmt, if any.
are added. The * suppression modifier (e.g., *i3 or *b4) suppresses
assignment from the field and can be used to skip over bytes or bits in
the data, without having to copy them to a dummy variable in the arg
list.
The seek field type s permits you to skip over data. This seeks to an
absolute position (s3) or a relative position (s+3) in the data, based on
whether or not the presence of the '+' sign. The seek value can be
specified as v and the next integer value from the argument list will be
used as the seek value.
csio_decode_visit() operates like csio_decode() except that instead of
placing the decoded contents of the buffer in variadic arguments, the
decoded buffer contents are returned to the user via the arg_put()
function that is passed in. The arg_put() function takes several
arguments:
hook The "hook" is a mechanism to allow the arg_put() function to save
state in between calls.
letter is the letter describing the format of the argument being passed
into the function.
val is a void pointer to the value being passed into the function.
count is the size of the value being passed into the arg_put()
function. The argument format determines the unit of measure.
name This is a text description of the field, if one was provided in
the fmt.
buff_decode() decodes an arbitrary data buffer using the method described
above for csio_decode().
buff_decode_visit() decodes an arbitrary data buffer using the method
described above for csio_decode_visit().
csio_encode() encodes the data_ptr portion (not the CDB!) of a ccb_scsiio
structure, using the method described above for csio_build().
csio_encode_visit() encodes the data_ptr portion (not the CDB!) of a
ccb_scsiio structure, using the method described above for
csio_build_visit().
buff_encode_visit() encodes an arbitrary data pointer, using the method
described above for csio_build_visit().
RETURN VALUES
csio_build(), csio_build_visit(), csio_encode(), csio_encode_visit(), and
buff_encode_visit() return the number of fields processed.
csio_decode(), csio_decode_visit(), buff_decode(), and
buff_decode_visit() return the number of assignments performed.
SEE ALSO
cam(3), pass(4), camcontrol(8)
HISTORY
The CAM versions of these functions are based upon similar functions
The old scsireq data structure was almost identical to the SGI /dev/scsi
data structure. If anyone knows the name of the authors it should go
here; Peter Dufault first read about it in a 1989 Sun Expert magazine.
The new CCB data structures are derived from the CAM-2 and CAM-3
specifications.
Peter Dufault implemented a clone of SGI's interface in 386BSD that led
to the original FreeBSD SCSI library and the related kernel ioctl. If
anyone needs that for compatibility, contact dufault@hda.com.
AUTHORS
Kenneth Merry <ken@FreeBSD.org> implemented the CAM versions of these
encoding and decoding functions. This current work is based upon earlier
work by Peter Dufault <dufault@hda.com>.
BUGS
There should probably be a function that encodes both the CDB and the
data buffer portions of a SCSI CCB. I discovered this while implementing
the arbitrary command execution code in camcontrol(8), but I have not yet
had time to implement such a function.
Some of the CCB flag descriptions really do not belong here. Rather they
belong in a generic CCB man page. Since that man page has not yet been
written, the shorter descriptions here will have to suffice.
FreeBSD 14.0-RELEASE-p11 March 13, 2017 FreeBSD 14.0-RELEASE-p11