+ return vchan_tx_prep(&c->vc, &txd->vd, flags);
+}
+
+static struct dma_async_tx_descriptor *sa11x0_dma_prep_dma_cyclic(
+ struct dma_chan *chan, dma_addr_t addr, size_t size, size_t period,
+ enum dma_transfer_direction dir, void *context)
+{
+ struct sa11x0_dma_chan *c = to_sa11x0_dma_chan(chan);
+ struct sa11x0_dma_desc *txd;
+ unsigned i, j, k, sglen, sgperiod;
+
+ /* SA11x0 channels can only operate in their native direction */
+ if (dir != (c->ddar & DDAR_RW ? DMA_DEV_TO_MEM : DMA_MEM_TO_DEV)) {
+ dev_err(chan->device->dev, "vchan %p: bad DMA direction: DDAR:%08x dir:%u\n",
+ &c->vc, c->ddar, dir);
+ return NULL;
+ }
+
+ sgperiod = DIV_ROUND_UP(period, DMA_MAX_SIZE & ~DMA_ALIGN);
+ sglen = size * sgperiod / period;
+
+ /* Do not allow zero-sized txds */
+ if (sglen == 0)
+ return NULL;
+
+ txd = kzalloc(sizeof(*txd) + sglen * sizeof(txd->sg[0]), GFP_ATOMIC);
+ if (!txd) {
+ dev_dbg(chan->device->dev, "vchan %p: kzalloc failed\n", &c->vc);
+ return NULL;
+ }
+
+ for (i = k = 0; i < size / period; i++) {
+ size_t tlen, len = period;
+
+ for (j = 0; j < sgperiod; j++, k++) {
+ tlen = len;
+
+ if (tlen > DMA_MAX_SIZE) {
+ unsigned mult = DIV_ROUND_UP(tlen, DMA_MAX_SIZE & ~DMA_ALIGN);
+ tlen = (tlen / mult) & ~DMA_ALIGN;
+ }
+
+ txd->sg[k].addr = addr;
+ txd->sg[k].len = tlen;
+ addr += tlen;
+ len -= tlen;
+ }
+
+ WARN_ON(len != 0);
+ }
+
+ WARN_ON(k != sglen);
+
+ txd->ddar = c->ddar;
+ txd->size = size;
+ txd->sglen = sglen;
+ txd->cyclic = 1;
+ txd->period = sgperiod;
+
+ return vchan_tx_prep(&c->vc, &txd->vd, DMA_PREP_INTERRUPT | DMA_CTRL_ACK);