read(9e) [sunos man page]

read(9E)							Driver Entry Points							  read(9E)

NAME

       read - read data from a device

SYNOPSIS

       #include <sys/types.h>
       #include <sys/errno.h>
       #include <sys/open.h>
       #include <sys/uio.h>
       #include <sys/cred.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       int prefixread(dev_t dev, struct uio *uio_p, cred_t *cred_p);

INTERFACE LEVEL

       Architecture independent level 1 (DDI/DKI). This entry point is optional.

PARAMETERS

       dev	       Device number.

       uio_p	       Pointer to the  uio(9S) structure that describes where the data is to be stored in user space.

       cred_p	       Pointer to the  user credential structure for the I/O transaction.

DESCRIPTION

       The driver  read() routine is called indirectly through cb_ops(9S) by the  read(2) system call. The  read() routine should check the valid-
       ity of the minor number component of dev and the user credential structure pointed to by   cred_p  (if  pertinent).   The   read()  routine
       should supervise the data transfer into the user space described by the	uio(9S) structure.

RETURN VALUES

       The  read() routine should return  0 for success, or the appropriate error number.

EXAMPLES

       Example 1: read() routine using physio()

       The following is an example of a read() routine using physio(9F) to perform reads from a non-seekable device:

	     static int
	     xxread(dev_t dev, struct uio *uiop, cred_t *credp)
	     {
		      int		  rval;
		      offset_t		  off;
		      int		  instance;
		      xx_t		  xx;

		      instance = getminor(dev);
		      xx = ddi_get_soft_state(xxstate, instance);
		      if (xx == NULL)
				return (ENXIO);
		      off = uiop->uio_loffset;
		      rval = physio(xxstrategy, NULL, dev, B_READ,
				xxmin, uiop);
		      uiop->uio_loffset = off;
		      return (rval);
	     }

SEE ALSO

       read(2), write(9E), physio(9F), cb_ops(9S), uio(9S)

       Writing Device Drivers

SunOS 5.10							    19 Nov 1997 							  read(9E)

awrite(9E)							Driver Entry Points							awrite(9E)

NAME

       awrite - asynchronous write to a device

SYNOPSIS

       #include <sys/uio.h>
       #include <sys/aio_req.h>
       #include <sys/cred.h>
       #include <sys/ddi.h>
       #include <sys/sunddi.h>

       intprefixawrite(dev_t dev, struct aio_req *aio_reqp, cred_t *cred_p);

INTERFACE LEVEL

       Solaris	DDI  specific  (Solaris  DDI).	This  entry  point  is	optional.  Drivers that do not support an  awrite() entry point should use
       nodev(9F)

PARAMETERS

       dev	       Device number.

       aio_reqp        Pointer to the  aio_req(9S) structure that describes where the data is stored.

       cred_p	       Pointer to the  credential structure.

DESCRIPTION

       The driver's awrite() routine is called to perform an asynchronous write. getminor(9F) can be used to  access the minor number component of
       the  dev argument. awrite() may use the	credential structure pointed to by  cred_p to check for superuser access by calling  drv_priv(9F).
       The  awrite() routine may also examine the  uio(9S) structure through  the   aio_req  structure	pointer,   aio_reqp.  awrite()	must  call
       aphysio(9F) with the aio_req pointer and a pointer to the driver's strategy(9E) routine.

       No fields of the uio(9S) structure pointed to by aio_req, other than uio_offset or uio_loffset, may be modified for non-seekable devices.

RETURN VALUES

       The  awrite() routine should return   0 for success, or the appropriate error number.

CONTEXT

       This function is called from user context only.

EXAMPLES

       Example 1: Using the awrite routine:

       The following is an example of an  awrite() routine:

       static int
       xxawrite(dev_t dev, struct aio_req *aio, cred_t *cred_p)
       {
	       int instance;
	       struct xxstate *xsp;

	       instance = getminor(dev);
	       xsp = ddi_get_soft_state(statep, instance);
	       /*Verify soft state structure has been allocated */
	       if (xsp == NULL)
			return (ENXIO);
	       return (aphysio(xxstrategy, anocancel, dev, B_WRITE, xxminphys, aio));
       }

SEE ALSO

       write(2),  aiowrite(3AIO),  aread(9E), read(9E), strategy(9E), write(9E), anocancel(9F), aphysio(9F), ddi_get_soft_state(9F), drv_priv(9F),
       getminor(9F), minphys(9F), nodev(9F), aio_req(9S), cb_ops(9S), uio(9S)

       Writing Device Drivers

BUGS

       There is no way other than calling aphysio(9F) to accomplish an asynchronous write.

SunOS 5.10							    28 Mar 1997 							awrite(9E)