static int pdc_rx_list_sg_add()

in bcm-pdc-mailbox.c [874:926]

• 39 lines of code
• 6 McCabe index (conditional complexity)

static int pdc_rx_list_sg_add(struct pdc_state *pdcs, struct scatterlist *sg)
{
	u32 flags = 0;
	u32 rx_avail;

	/*
	 * Num descriptors needed. Conservatively assume we need a descriptor
	 * for every entry from our starting point in the scatterlist.
	 */
	u32 num_desc;
	u32 desc_w = 0;	/* Number of tx descriptors written */
	u32 bufcnt;	/* Number of bytes of buffer pointed to by descriptor */
	dma_addr_t databufptr;	/* DMA address to put in descriptor */

	num_desc = (u32)sg_nents(sg);

	rx_avail = pdcs->nrxpost - NRXDACTIVE(pdcs->rxin, pdcs->rxout,
					      pdcs->nrxpost);
	if (unlikely(num_desc > rx_avail)) {
		pdcs->rxnobuf++;
		return -ENOSPC;
	}

	while (sg) {
		if (unlikely(pdcs->rxout == (pdcs->nrxd - 1)))
			flags = D64_CTRL1_EOT;
		else
			flags = 0;

		/*
		 * If sg buffer larger than PDC limit, split across
		 * multiple descriptors
		 */
		bufcnt = sg_dma_len(sg);
		databufptr = sg_dma_address(sg);
		while (bufcnt > PDC_DMA_BUF_MAX) {
			pdc_build_rxd(pdcs, databufptr, PDC_DMA_BUF_MAX, flags);
			desc_w++;
			bufcnt -= PDC_DMA_BUF_MAX;
			databufptr += PDC_DMA_BUF_MAX;
			if (unlikely(pdcs->rxout == (pdcs->nrxd - 1)))
				flags = D64_CTRL1_EOT;
			else
				flags = 0;
		}
		pdc_build_rxd(pdcs, databufptr, bufcnt, flags);
		desc_w++;
		sg = sg_next(sg);
	}
	pdcs->rx_ctx[pdcs->rx_msg_start].rxin_numd += desc_w;

	return PDC_SUCCESS;
}