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NAME    [Toc]    [Back]

     cam_open_device, cam_open_spec_device, cam_open_btl, cam_open_pass,
     cam_close_device, cam_close_spec_device, cam_getccb, cam_send_ccb,
     cam_freeccb, cam_path_string, cam_device_dup, cam_device_copy,
     cam_get_device -- CAM user library

LIBRARY    [Toc]    [Back]

     Common Access Method User Library (libcam, -lcam)

SYNOPSIS    [Toc]    [Back]

     #include <stdio.h>
     #include <camlib.h>

     struct cam_device *
     cam_open_device(const char *path, int flags);

     struct cam_device *
     cam_open_spec_device(const char *dev_name, int unit, int flags,
	 struct cam_device *device);

     struct cam_device *
     cam_open_btl(path_id_t path_id, target_id_t target_id,
	 lun_id_t target_lun, int flags, struct cam_device *device);

     struct cam_device *
     cam_open_pass(const char *path, int flags, struct cam_device *device);

     cam_close_device(struct cam_device *dev);

     cam_close_spec_device(struct cam_device *dev);

     union ccb *
     cam_getccb(struct cam_device *dev);

     cam_send_ccb(struct cam_device *device, union ccb *ccb);

     cam_freeccb(union ccb *ccb);

     char *
     cam_path_string(struct cam_device *dev, char *str, int len);

     struct cam_device *
     cam_device_dup(struct cam_device *device);

     cam_device_copy(struct cam_device *src, struct cam_device *dst);

     cam_get_device(const char *path, char *dev_name, int devnamelen,
	 int *unit);

DESCRIPTION    [Toc]    [Back]

     The CAM library consists of a number of functions designed to aid in programming
 with the CAM subsystem.  This man page covers the basic set of
     library functions.  More functions are documented in the man pages listed

     Many of the CAM library functions use the cam_device structure:

     struct cam_device {
	     char	     device_path[MAXPATHLEN+1];/*
							* Pathname of the
							* device given by the
							* user. This may be
							* null if the user
							* states the device
							* name and unit number
							* separately.
	     char	     given_dev_name[DEV_IDLEN+1];/*
							  * Device name given by
							  * the user.
	     u_int32_t	     given_unit_number; 	 /*
							  * Unit number given by
							  * the user.
	     char	     device_name[DEV_IDLEN+1];/*
						       * Name of the device,
						       * e.g. 'pass'
	     u_int32_t	     dev_unit_num;   /* Unit number of the passthrough
					      * device associated with this
					      * particular device.

	     char	     sim_name[SIM_IDLEN+1];/*
						    * Controller name, e.g.'ahc'
	     u_int32_t	     sim_unit_number; /* Controller unit number */
	     u_int32_t	     bus_id;	      /* Controller bus number */
	     lun_id_t	     target_lun;      /* Logical Unit Number */
	     target_id_t     target_id;       /* Target ID */
	     path_id_t	     path_id;	      /* System SCSI bus number */
	     u_int16_t	     pd_type;	      /* type of peripheral device */
	     struct scsi_inquiry_data inq_data;  /* SCSI Inquiry data */
	     u_int8_t	     serial_num[252]; /* device serial number */
	     u_int8_t	     serial_num_len;  /* length of the serial number */
	     u_int8_t	     sync_period;     /* Negotiated sync period */
	     u_int8_t	     sync_offset;     /* Negotiated sync offset */
	     u_int8_t	     bus_width;       /* Negotiated bus width */
	     int	     fd;	      /* file descriptor for device */

     cam_open_device() takes as arguments a string describing the device it is
     to open, and flags suitable for passing to open(2).  The "path" passed in
     may actually be most any type of string that contains a device name and
     unit number to be opened.	The string will be parsed by cam_get_device()
     into a device name and unit number.  Once the device name and unit number
     are determined, a lookup is performed to determine the passthrough device
     that corresponds to the given device.  cam_open_device() is rather simple
     to use, but it isn't really suitable for general use because its behavior
     isn't necessarily deterministic.  Programmers writing new applications
     should make the extra effort to use one of the other open routines documented

     cam_open_spec_device() opens the pass(4) device that corresponds to the
     device name and unit number passed in.  The flags should be flags suitable
 for passing to open(2).  The device argument is optional.  The user
     may supply pre-allocated space for the cam_device structure.  If the
     device argument is NULL, cam_open_spec_device() will allocate space for
     the cam_device structure using malloc(3).

     cam_open_btl() is similar to cam_open_spec_device(), except that it takes
     a SCSI bus, target and logical unit instead of a device name and unit
     number as arguments.  The path_id argument is the CAM equivalent of a
     SCSI bus number.  It represents the logical bus number in the system.
     The flags should be flags suitable for passing to open(2).  As with
     cam_open_spec_device(), the device argument is optional.

     cam_open_pass() takes as an argument the path of a pass(4) device to
     open.  No translation or lookup is performed, so the path passed in must
     be that of a CAM pass(4) device.  The flags should be flags suitable for
     passing to open(2).  The device argument, as with cam_open_spec_device()
     and cam_open_btl(), should be NULL if the user wants the CAM library to
     allocate space for the cam_device structure.  cam_close_device() frees
     the cam_device structure allocated by one of the above open() calls, and
     closes the file descriptor to the passthrough device.  This routine
     should not be called if the user allocated space for the cam_device
     structure.  Instead, the user should call cam_close_spec_device().

     cam_close_spec_device() merely closes the file descriptor opened in one
     of the open() routines described above.  This function should be called
     when the cam_device structure was allocated by the caller, rather than
     the CAM library.

     cam_getccb() allocates a CCB using malloc(3) and sets fields in the CCB
     header using values from the cam_device structure.

     cam_send_ccb() sends the given ccb to the device described in the
     cam_device structure.

     cam_freeccb() frees CCBs allocated by cam_getccb().

     cam_path_string() takes as arguments a cam_device structure, and a string
     with length len.  It creates a colon-terminated printing prefix string
     similar to the ones used by the kernel.  e.g.:  "(cd0:ahc1:0:4:0): ".
     cam_path_string() will place at most len-1 characters into str.  The
     len'th character will be the terminating `\0'.

     cam_device_dup() operates in a fashion similar to strdup(3).  It allocates
 space for a cam_device structure and copies the contents of the
     passed-in device structure to the newly allocated structure.

     cam_device_copy() copies the src structure to dst.

     cam_get_device() takes a path argument containing a string with a device
     name followed by a unit number.  It then breaks the string down into a
     device name and unit number, and passes them back in dev_name and unit,
     respectively.  cam_get_device() can handle strings of the following
     forms, at least:


     cam_get_device() is provided as a convenience function for applications
     that need to provide functionality similar to cam_open_device().  Programmers
 are encouraged to use more deterministic methods of obtaining
     device names and unit numbers if possible.

RETURN VALUES    [Toc]    [Back]

     cam_open_device(), cam_open_spec_device(), cam_open_btl(), and
     cam_open_pass() return a pointer to a cam_device structure, or NULL if
     there was an error.

     cam_getccb() returns an allocated and partially initialized CCB, or NULL
     if allocation of the CCB failed.

     cam_send_ccb() returns a value of -1 if an error occured, and errno is
     set to indicate the error.

     cam_path_string() returns a filled printing prefix string as a convenience.
  This is the same str that is passed into cam_path_string().

     cam_device_dup() returns a copy of the device passed in, or NULL if an
     error occurred.

     cam_get_device() returns 0 for success, and -1 to indicate failure.

     If an error is returned from one of the base CAM library functions
     described here, the reason for the error is generally printed in the
     global string cam_errbuf which is CAM_ERRBUF_SIZE characters long.

SEE ALSO    [Toc]    [Back]

     cam_cdbparse(3), pass(4), camcontrol(8)

HISTORY    [Toc]    [Back]

     The CAM library first appeared in FreeBSD 3.0.

AUTHORS    [Toc]    [Back]

     Kenneth Merry <ken@FreeBSD.org>

BUGS    [Toc]    [Back]

     cam_open_device() doesn't check to see if the path passed in is a symlink
     to something.  It also doesn't check to see if the path passed in is an
     actual pass(4) device.  The former would be rather easy to implement, but
     the latter would require a definitive way to identify a device node as a
     pass(4) device.

     Some of the functions are possibly mis-named or poorly named.

FreeBSD 5.2.1		       October 10, 1998 		 FreeBSD 5.2.1
[ Back ]
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