Manual Pages for UNIX Operating System command usage for man scsi_alloc_consistent_buf

Kernel Functions for Drivers        scsi_alloc_consistent_buf(9F)



NAME
     scsi_alloc_consistent_buf - allocate an I/O buffer for  SCSI
     DMA

SYNOPSIS
     #include 



     struct buf *scsi_alloc_consistent_buf(structscsi_address*ap,
          struct buf *bp, size_t datalen, uint_t bflags,
          int (*callback)(caddr_t), caddr_t arg);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

PARAMETERS
     ap          Pointer to the scsi_address(9S) structure.


     bp          Pointer to the buf(9S) structure.


     datalen     Number of bytes for the data buffer.


     bflags      Flags setting for the allocated  buffer  header.
                 This should either be B_READ or B_WRITE.


     callback    A pointer to a callback function,  NULL_FUNC  or
                 SLEEP_FUNC.


     arg         The callback function argument.


DESCRIPTION
     The scsi_alloc_consistent_buf() function returns allocates a
     buffer  header  and  the  associated  data buffer for direct
     memory access (DMA) transfer. This buffer is allocated  from
     the  iobp  space, which is considered consistent memory. For
     more     details,     see     ddi_dma_mem_alloc(9F)      and
     ddi_dma_sync(9F).


     For buffers allocated via  scsi_alloc_consistent_buf(),  and
     marked  with  the PKT_CONSISTENT flag via scsi_init_pkt(9F),
     the HBA driver must ensure that the data  transfer  for  the
     command is correctly synchronized before the target driver's
     command completion callback is performed.



SunOS 5.11          Last change: 16 Jan 2006                    1






Kernel Functions for Drivers        scsi_alloc_consistent_buf(9F)



     If bp is NULL, a new buffer header will be  allocated  using
     getrbuf(9F).  In  addition,  if  datalen  is non-zero, a new
     buffer will be allocated using ddi_dma_mem_alloc(9F).


     callback indicates what the  allocator  routines  should  do
     when direct memory access (DMA) resources are not available;
     the valid values are:

     NULL_FUNC       Do not wait for  resources.  Return  a  NULL
                     pointer.


     SLEEP_FUNC      Wait indefinitely for resources.


     Other Values    callback points to a function that is called
                     when  resources  may become available. call-
                     back must return either 0  (indicating  that
                     it   attempted  to  allocate  resources  but
                     failed to do so), in which case  it  is  put
                     back  on a list to be called again later, or
                     1 indicating either  success  in  allocating
                     resources  or  indicating  that it no longer
                     cares for a retry. The last argument arg  is
                     supplied to the callback function when it is
                     invoked.


RETURN VALUES
     The scsi_alloc_consistent_buf() function returns  a  pointer
     to  a  buf(9S)  structure  on  success.  It  returns NULL if
     resources  are  not  available  even  if  waitfunc  was  not
     SLEEP_FUNC.

CONTEXT
     If callback is SLEEP_FUNC, then this routine may  be  called
     only  from  user-level  code.  Otherwise,  it  may be called
     fromuser, interrupt, or kernel context. The  callback  func-
     tion may not block or call routines that block.

EXAMPLES
     Example 1 Allocate a request sense  packet  with  consistent
     DMA resources attached.

          bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
                SENSE_LENGTH, B_READ, SLEEP_FUNC, NULL);
           rqpkt = scsi_init_pkt(&devp->sd_address,
                NULL, bp, CDB_GROUP0, 1, 0,
                PKT_CONSISTENT, SLEEP_FUNC, NULL);





SunOS 5.11          Last change: 16 Jan 2006                    2






Kernel Functions for Drivers        scsi_alloc_consistent_buf(9F)



     Example 2 Allocate an inquiry  packet  with  consistent  DMA
     resources attached.

           bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
                SUN_INQSIZE, B_READ, canwait, NULL);
           if (bp) {
            pkt = scsi_init_pkt(&devp->sd_address, NULL, bp,
                 CDB_GROUP0, 1, PP_LEN, PKT_CONSISTENT,
                 canwait, NULL);
           }


SEE ALSO
     ddi_dma_mem_alloc(9F),    ddi_dma_sync(9F),     getrbuf(9F),
     scsi_destroy_pkt(9F),                     scsi_init_pkt(9F),
     scsi_free_consistent_buf(9F), buf(9S), scsi_address(9S)


     Writing Device Drivers




































SunOS 5.11          Last change: 16 Jan 2006                    3