+/*
+ * A PaRAM set configuration abstraction used by other modes
+ * @chan: Channel who's PaRAM set we're configuring
+ * @pset: PaRAM set to initialize and setup.
+ * @src_addr: Source address of the DMA
+ * @dst_addr: Destination address of the DMA
+ * @burst: In units of dev_width, how much to send
+ * @dev_width: How much is the dev_width
+ * @dma_length: Total length of the DMA transfer
+ * @direction: Direction of the transfer
+ */
+static int edma_config_pset(struct dma_chan *chan, struct edmacc_param *pset,
+ dma_addr_t src_addr, dma_addr_t dst_addr, u32 burst,
+ enum dma_slave_buswidth dev_width, unsigned int dma_length,
+ enum dma_transfer_direction direction)
+{
+ struct edma_chan *echan = to_edma_chan(chan);
+ struct device *dev = chan->device->dev;
+ int acnt, bcnt, ccnt, cidx;
+ int src_bidx, dst_bidx, src_cidx, dst_cidx;
+ int absync;
+
+ acnt = dev_width;
+ /*
+ * If the maxburst is equal to the fifo width, use
+ * A-synced transfers. This allows for large contiguous
+ * buffer transfers using only one PaRAM set.
+ */
+ if (burst == 1) {
+ /*
+ * For the A-sync case, bcnt and ccnt are the remainder
+ * and quotient respectively of the division of:
+ * (dma_length / acnt) by (SZ_64K -1). This is so
+ * that in case bcnt over flows, we have ccnt to use.
+ * Note: In A-sync tranfer only, bcntrld is used, but it
+ * only applies for sg_dma_len(sg) >= SZ_64K.
+ * In this case, the best way adopted is- bccnt for the
+ * first frame will be the remainder below. Then for
+ * every successive frame, bcnt will be SZ_64K-1. This
+ * is assured as bcntrld = 0xffff in end of function.
+ */
+ absync = false;
+ ccnt = dma_length / acnt / (SZ_64K - 1);
+ bcnt = dma_length / acnt - ccnt * (SZ_64K - 1);
+ /*
+ * If bcnt is non-zero, we have a remainder and hence an
+ * extra frame to transfer, so increment ccnt.
+ */
+ if (bcnt)
+ ccnt++;
+ else
+ bcnt = SZ_64K - 1;
+ cidx = acnt;
+ } else {
+ /*
+ * If maxburst is greater than the fifo address_width,
+ * use AB-synced transfers where A count is the fifo
+ * address_width and B count is the maxburst. In this
+ * case, we are limited to transfers of C count frames
+ * of (address_width * maxburst) where C count is limited
+ * to SZ_64K-1. This places an upper bound on the length
+ * of an SG segment that can be handled.
+ */
+ absync = true;
+ bcnt = burst;
+ ccnt = dma_length / (acnt * bcnt);
+ if (ccnt > (SZ_64K - 1)) {
+ dev_err(dev, "Exceeded max SG segment size\n");
+ return -EINVAL;
+ }
+ cidx = acnt * bcnt;
+ }
+
+ if (direction == DMA_MEM_TO_DEV) {
+ src_bidx = acnt;
+ src_cidx = cidx;
+ dst_bidx = 0;
+ dst_cidx = 0;
+ } else if (direction == DMA_DEV_TO_MEM) {
+ src_bidx = 0;
+ src_cidx = 0;
+ dst_bidx = acnt;
+ dst_cidx = cidx;
+ } else {
+ dev_err(dev, "%s: direction not implemented yet\n", __func__);
+ return -EINVAL;
+ }
+
+ pset->opt = EDMA_TCC(EDMA_CHAN_SLOT(echan->ch_num));
+ /* Configure A or AB synchronized transfers */
+ if (absync)
+ pset->opt |= SYNCDIM;
+
+ pset->src = src_addr;
+ pset->dst = dst_addr;
+
+ pset->src_dst_bidx = (dst_bidx << 16) | src_bidx;
+ pset->src_dst_cidx = (dst_cidx << 16) | src_cidx;
+
+ pset->a_b_cnt = bcnt << 16 | acnt;
+ pset->ccnt = ccnt;
+ /*
+ * Only time when (bcntrld) auto reload is required is for
+ * A-sync case, and in this case, a requirement of reload value
+ * of SZ_64K-1 only is assured. 'link' is initially set to NULL
+ * and then later will be populated by edma_execute.
+ */
+ pset->link_bcntrld = 0xffffffff;
+ return absync;
+}
+