sunos man page for ddi_dev_regsize

ddi_dev_regsize(9F)					   Kernel Functions for Drivers 				       ddi_dev_regsize(9F)

NAME
       ddi_dev_regsize - return the size of a device's register

SYNOPSIS
       #include <sys/conf.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int ddi_dev_regsize(dev_info_t *dip, uint_t rnumber, off_t *resultp);

INTERFACE LEVEL
       Solaris DDI specific (Solaris DDI).

PARAMETERS
       dip	       A pointer to the device's dev_info structure.

       rnumber	       The ordinal register number. Device registers are associated with a dev_info and are enumerated in arbitrary sets from 0 on
		       up. The number of registers a device has can be determined from a call to ddi_dev_nregs(9F).

       resultp	       Pointer to an integer that holds the size, in bytes, of the described register (if it exists).

DESCRIPTION
       ddi_dev_regsize() returns the size, in bytes, of the device register specified by dip and rnumber. This is useful when, for example, one of
       the registers is a frame buffer with a varying size known only to its proms.

RETURN VALUES
       ddi_dev_regsize() returns:

       DDI_SUCCESS     A successful return. The size, in bytes, of the specified register, is set in resultp.

       DDI_FAILURE     An invalid (nonexistent) register number was specified.

CONTEXT
       ddi_dev_regsize() can be called from user or interrupt context.

SEE ALSO
       ddi_dev_nintrs(9F), ddi_dev_nregs(9F)

       Writing Device Drivers

SunOS 5.10							    24 Oct 1991 					       ddi_dev_regsize(9F)