eni_transmit.c

基于组件方式开发操作系统的OSKIT源代码

	long		j;
	u_long		dma_avail;
	u_long		dma_start;
	Eni_mem		tx_send;
	u_long		*up;
	KBuffer		*m0 = m, *m1, *mprev = NULL;
	caddr_t		cp, bfr;
	u_int		len, align;
	int		compressed = 0;

#ifdef	DIAGNOSTIC
	if ( eni_pdu_print )
		atm_dev_pdu_print ( cup, cvp, m, "eni output" );
#endif

	/*
	 * Re-entry point for after buffer compression (if needed)
	 */
retry:

	/*
	 * We can avoid traversing the buffer list twice by building
	 * the middle (minus header and trailer) dma list at the
	 * same time we massage address and size alignments. Since
	 * this list remains local until we determine we've enough
	 * room, we're not going to trash anything by not checking
	 * sizes, etc. yet. Skip first entry to be used later to skip
	 * descriptor word.
	 */
	j = 2;
	/*
	 * Do data positioning for address and length alignment
	 */
	while ( m ) {
		u_long	buf_addr;	/* For passing addr to eni_set_dma() */

		/*
		 * Get rid of any zero length buffers
		 */
		if ( KB_LEN ( m ) == 0 ) {
			if ( mprev ) {
				KB_UNLINK ( m, mprev, m1 );
			} else {
				KB_UNLINKHEAD ( m, m1 );
				m0 = m1;
			}
			m = m1;
			continue;
		}
		/*
		 * Get start of data onto full-word alignment
		 */
		KB_DATASTART ( m, cp, caddr_t );
		if ( align = ((u_int)cp) & (sizeof(u_long)-1)) {
			/*
			 * Gotta slide the data up
			 */
			eup->eu_stats.eni_st_drv.drv_xm_segnoal++;
			bfr = cp - align;
			KM_COPY ( cp, bfr, KB_LEN ( m ) );
			KB_HEADMOVE ( m, -align );
		} else {
			/*
			 * Data already aligned
			 */
			bfr = cp;
		}
		/*
		 * Now work on getting the data length correct
		 */
		len = KB_LEN ( m );
		while ( ( align = ( len & (sizeof(u_long)-1))) &&
			(m1 = KB_NEXT ( m ) ) ) {

			/*
			 * Have to move some data from following buffer(s)
			 * to word-fill this buffer
			 */
			u_int ncopy = MIN ( sizeof(u_long) - align,
				KB_LEN ( m1 ) );

			if ( ncopy ) {
				/*
				 * Move data to current buffer
				 */
				caddr_t	dest;

				eup->eu_stats.eni_st_drv.drv_xm_seglen++;
				KB_DATASTART ( m1, cp, caddr_t );
				dest = bfr + len;
				KB_HEADADJ ( m1, -ncopy );
				KB_TAILADJ ( m, ncopy );
				len += ncopy;
				while ( ncopy-- ) {
					*dest++ = *cp++;
				}
			}

			/*
			 * If we've drained the buffer, free it
			 */
			if ( KB_LEN ( m1 ) == 0 ) {
				KBuffer *m2;

				KB_UNLINK ( m1, m, m2 );
			}
		}

		/*
		 * Address and size are now aligned. Build dma list
		 * using TX channel 0. Also, round length up to a word
		 * size which should only effect the last buffer in the
		 * chain. This works because the PDU length is maintained
		 * seperately and we're not really adjusting the buffer's
		 * idea of its length.
		 */
		KB_DATASTART ( m, buf_addr, u_long );
		if ( eni_set_dma ( eup, 0, dma, TEMP_DMA_SIZE, &j, 0,
		    buf_addr, KB_LEN ( m ) ) < 0 ) {
			/*
			 * Failed to build DMA list. First, we'll try to
			 * compress the buffer chain into a smaller number
			 * of buffers. After compressing, we'll try to send
			 * the new buffer chain. If we still fail, then
			 * we'll drop the pdu.
			 */
			if ( compressed ) {
#ifdef	DO_LOG
				log ( LOG_ERR,
					"eni_output: eni_set_dma failed\n" );
#endif
				eup->eu_pif.pif_oerrors++;
				KB_FREEALL ( m0 );
				return;
			}

			eup->eu_stats.eni_st_drv.drv_xm_maxpdu++;

			m = atm_dev_compress ( m0 );
			if ( m == NULL ) {
#ifdef	DO_LOG
				log ( LOG_ERR,
				    "eni_output: atm_dev_compress() failed\n" );
#endif
				eup->eu_pif.pif_oerrors++;
				return;
			}

			/*
			 * Reset to new head of buffer chain
			 */
			m0 = m;

			/*
			 * Indicate we've been through here
			 */
			compressed = 1;

			/*
			 * Retry to build the DMA descriptors for the newly
			 *  compressed buffer chain
			 */
			goto retry;

		}

		/*
		 * Now count the length
		 */
		pdulen += KB_LEN ( m );

		/*
		 * Bump counters and get ready for next buffer
		 */
		mprev = m;
		m = KB_NEXT ( m );
	}

	/*
	 * Get a buffer to use in a private queue so that we can
	 * reclaim resources after the DMA has finished.
	 */
	KB_ALLOC ( m, ENI_SMALL_BSIZE, KB_F_NOWAIT, KB_T_DATA );
	if ( m ) {
		/*
		 * Link the PDU onto our new head
		 */
		KB_NEXT ( m ) = m0;
	} else {
		/*
		 * Drop this PDU and let the sender try again.
		 */
		eup->eu_stats.eni_st_drv.drv_xm_norsc++;
#ifdef	DO_LOG
		log(LOG_ERR, "eni_output: Unable to allocate drain buffer.\n");
#endif
		eup->eu_pif.pif_oerrors++;
		KB_FREEALL ( m0 );
		return;
	}

	s = splnet();

	/*
	 * Calculate size of buffer necessary to store PDU. If this
	 * is an AAL5 PDU, we'll need to know where to stuff the length
	 * value in the trailer.
	 */
	/*
	 * AAL5 PDUs need an extra two words for control/length and
	 * CRC. Check for AAL5 and add requirements here.
	 */
	if (aal5 = (evp->ev_connvc->cvc_attr.aal.type == ATM_AAL5))
		size = pdulen + 2 * sizeof(long);
	else
		size = pdulen;
	/*
	 * Pad to next complete cell boundary
	 */
	size += (BYTES_PER_CELL - 1);
	size -= size % BYTES_PER_CELL;
	/*
	 * Convert size to words and add 2 words overhead for every
	 * PDU (descriptor and cell header).
	 */
	size = (size >> 2) + 2;

	/*
	 * First, check to see if there's enough buffer space to
	 * store the PDU. We do this by checking to see if the size
	 * required crosses the eu_txfirst pointer.  However, we don't
	 * want to exactly fill the buffer, because we won't be able to
	 * distinguish between a full and empty buffer.
	 */
	if ( eup->eu_txpos == eup->eu_txfirst )
		buf_avail = eup->eu_txsize;
	else
	    if ( eup->eu_txpos > eup->eu_txfirst )
		buf_avail = eup->eu_txsize - ( eup->eu_txpos - eup->eu_txfirst );
	    else
		buf_avail = eup->eu_txfirst - eup->eu_txpos;

	if ( size >= buf_avail )
	{
		/*
		 * No buffer space in the adapter to store this PDU.
		 * Drop PDU and return.
		 */
		eup->eu_stats.eni_st_drv.drv_xm_nobuf++;
#ifdef	DO_LOG
		log ( LOG_ERR,
			"eni_output: not enough room in buffer\n" );
#endif
		eup->eu_pif.pif_oerrors++;
	 	KB_FREEALL ( m );
		(void) splx(s);
		return;
	}

	/*
	 * Find out where current DMA pointers are at
	 */
	dma_start = dma_wr = eup->eu_midway[MIDWAY_TX_WR];
	dma_rd = eup->eu_midway[MIDWAY_TX_RD];

	/*
	 * Figure out how much DMA room we have available
	 */
	if ( dma_rd == dma_wr )	{		/* Queue is empty */
		dma_avail = DMA_LIST_SIZE;
	} else {
		dma_avail = ( dma_rd + DMA_LIST_SIZE - dma_wr )
		    & ( DMA_LIST_SIZE - 1 );
	}
	/*
	 * Check to see if we can describe this PDU or if we're:
	 * out of room, will wrap past recovered resources.
	 */
	if ( dma_avail < (j / 2 + 4) ||
	    ( dma_wr + (j / 2 + 4) > eup->eu_txdmawr + DMA_LIST_SIZE ) ) {
		/*
		 * No space to insert DMA list into queue. Drop this PDU.
		 */
		eup->eu_stats.eni_st_drv.drv_xm_nodma++;
#ifdef	DO_LOG
		log ( LOG_ERR,
			"eni_output: not enough room in DMA queue\n" );
#endif
		eup->eu_pif.pif_oerrors++;
		KB_FREEALL( m );
		(void) splx(s);
		return;
	}

	/*
	 * Create DMA descriptor for header. There is a descriptor word
	 * and also a cell header word which we'll set manually.
	 */
	dma[0] = (((int)(eup->eu_txpos + 2) & (eup->eu_txsize-1)) <<
	    DMA_COUNT_SHIFT) | DMA_JK;
	dma[1] = 0;

	/*
	 * JK for AAL5 trailer. Set END bit as well.
	 */
	if ( aal5 ) {
	    dma[j++] = (((int)(eup->eu_txpos+size) & (eup->eu_txsize-1)) <<
		DMA_COUNT_SHIFT) | DMA_END_BIT | DMA_JK;
	    dma[j++] = 0;
	} else {
		dma[j-2] |= DMA_END_BIT;	/* Backup and set END bit */
	}

	/*
	 * Find out where in adapter memory this TX buffer starts.
	 */
	tx_send = (Eni_mem)
	    ((((int)eup->eu_midway[MIDWAY_TXPLACE] & 0x7ff) << ENI_LOC_PREDIV) +
		    (int)eup->eu_ram);

	/*
	 * Set descriptor word
	 */
	tx_send[eup->eu_txpos] =
		(MIDWAY_UNQ_ID << 28) | (aal5 ? 1 << 27 : 0)
			| (size / WORDS_PER_CELL);
	/*
	 * Set cell header
	 */
	tx_send[(eup->eu_txpos+1)&(eup->eu_txsize-1)] = 
		evp->ev_connvc->cvc_vcc->vc_vci << 4;

	/*
	 * We've got all our resources, count the stats
	 */
	if ( aal5 ) {
		/*
		 * If this is an AAL5 PDU, we need to set the length
		 */
		tx_send[(eup->eu_txpos+size-2) &
			(eup->eu_txsize-1)] = pdulen;
		/*
		 * Increment AAL5 stats
		 */
		eup->eu_stats.eni_st_aal5.aal5_pdu_xmit++;
		eup->eu_stats.eni_st_aal5.aal5_xmit += (size - 2) / WORDS_PER_CELL;
	} else {
		/*
		 * Increment AAL0 stats
		 */
		eup->eu_stats.eni_st_aal0.aal0_xmit += (size - 2) / WORDS_PER_CELL;
	}
	/*
	 * Increment ATM stats
	 */
	eup->eu_stats.eni_st_atm.atm_xmit += (size - 2) / WORDS_PER_CELL;

	/*
	 * Store the DMA list
	 */
	j = j >> 1;
	for ( i = 0; i < j; i++ ) {
		eup->eu_txdma[dma_wr*2] = dma[i*2];
		eup->eu_txdma[dma_wr*2+1] = dma[i*2+1];
		dma_wr = (dma_wr+1) & (DMA_LIST_SIZE-1);
	}

	/*
	 * Build drain buffer
	 *
	 * We toss four words in to help keep track of this
	 * PDU. The first is a pointer to the VC control block
	 * so we can find which VCI this went out on, the second
	 * is the start and stop pointers for the DMA list which
	 * describes this PDU, the third is the PDU length
	 * since we'll want to know that for stats gathering,
	 * and the fourth is the number of DMA words.
	 */
	KB_DATASTART ( m, up, u_long * );
	*up++ = (u_long)cvp;
	*up++ = dma_start << 16 | dma_wr;
	*up++ = pdulen;
	*up = size;

	/*
	 * Set length of our buffer
	 */
	KB_LEN ( m ) = 4 * sizeof ( long );

	/*
	 * Place buffers onto transmit queue for draining
	 */
	s2 = splimp();
	IF_ENQUEUE ( &eup->eu_txqueue, m );
	(void) splx(s2);

	/*
	 * Update next word to be stored
	 */
	eup->eu_txpos = ((eup->eu_txpos + size) & (eup->eu_txsize - 1));

	/*
	 * Update MIDWAY_TX_WR pointer
	 */
	eup->eu_midway[MIDWAY_TX_WR] = dma_wr;
	
	(void) splx ( s );

	return;
}