+static struct dma_async_tx_descriptor *
+mpc_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
+ unsigned int sg_len, enum dma_transfer_direction direction,
+ unsigned long flags, void *context)
+{
+ struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
+ struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+ struct mpc_dma_desc *mdesc = NULL;
+ dma_addr_t per_paddr;
+ u32 tcd_nunits;
+ struct mpc_dma_tcd *tcd;
+ unsigned long iflags;
+ struct scatterlist *sg;
+ size_t len;
+ int iter, i;
+
+ /* Currently there is no proper support for scatter/gather */
+ if (sg_len != 1)
+ return NULL;
+
+ if (!is_slave_direction(direction))
+ return NULL;
+
+ for_each_sg(sgl, sg, sg_len, i) {
+ spin_lock_irqsave(&mchan->lock, iflags);
+
+ mdesc = list_first_entry(&mchan->free,
+ struct mpc_dma_desc, node);
+ if (!mdesc) {
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+ /* Try to free completed descriptors */
+ mpc_dma_process_completed(mdma);
+ return NULL;
+ }
+
+ list_del(&mdesc->node);
+
+ if (direction == DMA_DEV_TO_MEM) {
+ per_paddr = mchan->src_per_paddr;
+ tcd_nunits = mchan->src_tcd_nunits;
+ } else {
+ per_paddr = mchan->dst_per_paddr;
+ tcd_nunits = mchan->dst_tcd_nunits;
+ }
+
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+
+ if (per_paddr == 0 || tcd_nunits == 0)
+ goto err_prep;
+
+ mdesc->error = 0;
+ mdesc->will_access_peripheral = 1;
+
+ /* Prepare Transfer Control Descriptor for this transaction */
+ tcd = mdesc->tcd;
+
+ memset(tcd, 0, sizeof(struct mpc_dma_tcd));
+
+ if (!IS_ALIGNED(sg_dma_address(sg), 4))
+ goto err_prep;
+
+ if (direction == DMA_DEV_TO_MEM) {
+ tcd->saddr = per_paddr;
+ tcd->daddr = sg_dma_address(sg);
+ tcd->soff = 0;
+ tcd->doff = 4;
+ } else {
+ tcd->saddr = sg_dma_address(sg);
+ tcd->daddr = per_paddr;
+ tcd->soff = 4;
+ tcd->doff = 0;
+ }
+
+ tcd->ssize = MPC_DMA_TSIZE_4;
+ tcd->dsize = MPC_DMA_TSIZE_4;
+
+ len = sg_dma_len(sg);
+ tcd->nbytes = tcd_nunits * 4;
+ if (!IS_ALIGNED(len, tcd->nbytes))
+ goto err_prep;
+
+ iter = len / tcd->nbytes;
+ if (iter >= 1 << 15) {
+ /* len is too big */
+ goto err_prep;
+ }
+ /* citer_linkch contains the high bits of iter */
+ tcd->biter = iter & 0x1ff;
+ tcd->biter_linkch = iter >> 9;
+ tcd->citer = tcd->biter;
+ tcd->citer_linkch = tcd->biter_linkch;
+
+ tcd->e_sg = 0;
+ tcd->d_req = 1;
+
+ /* Place descriptor in prepared list */
+ spin_lock_irqsave(&mchan->lock, iflags);
+ list_add_tail(&mdesc->node, &mchan->prepared);
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+ }
+
+ return &mdesc->desc;
+
+err_prep:
+ /* Put the descriptor back */
+ spin_lock_irqsave(&mchan->lock, iflags);
+ list_add_tail(&mdesc->node, &mchan->free);
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+
+ return NULL;
+}
+
+static int mpc_dma_device_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+ unsigned long arg)
+{
+ struct mpc_dma_chan *mchan;
+ struct mpc_dma *mdma;
+ struct dma_slave_config *cfg;
+ unsigned long flags;
+
+ mchan = dma_chan_to_mpc_dma_chan(chan);
+ switch (cmd) {
+ case DMA_TERMINATE_ALL:
+ /* Disable channel requests */
+ mdma = dma_chan_to_mpc_dma(chan);
+
+ spin_lock_irqsave(&mchan->lock, flags);
+
+ out_8(&mdma->regs->dmacerq, chan->chan_id);
+ list_splice_tail_init(&mchan->prepared, &mchan->free);
+ list_splice_tail_init(&mchan->queued, &mchan->free);
+ list_splice_tail_init(&mchan->active, &mchan->free);
+
+ spin_unlock_irqrestore(&mchan->lock, flags);
+
+ return 0;
+
+ case DMA_SLAVE_CONFIG:
+ /*
+ * Software constraints:
+ * - only transfers between a peripheral device and
+ * memory are supported;
+ * - only peripheral devices with 4-byte FIFO access register
+ * are supported;
+ * - minimal transfer chunk is 4 bytes and consequently
+ * source and destination addresses must be 4-byte aligned
+ * and transfer size must be aligned on (4 * maxburst)
+ * boundary;
+ * - during the transfer RAM address is being incremented by
+ * the size of minimal transfer chunk;
+ * - peripheral port's address is constant during the transfer.
+ */
+
+ cfg = (void *)arg;
+
+ if (cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES ||
+ cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES ||
+ !IS_ALIGNED(cfg->src_addr, 4) ||
+ !IS_ALIGNED(cfg->dst_addr, 4)) {
+ return -EINVAL;
+ }
+
+ spin_lock_irqsave(&mchan->lock, flags);
+
+ mchan->src_per_paddr = cfg->src_addr;
+ mchan->src_tcd_nunits = cfg->src_maxburst;
+ mchan->dst_per_paddr = cfg->dst_addr;
+ mchan->dst_tcd_nunits = cfg->dst_maxburst;
+
+ /* Apply defaults */
+ if (mchan->src_tcd_nunits == 0)
+ mchan->src_tcd_nunits = 1;
+ if (mchan->dst_tcd_nunits == 0)
+ mchan->dst_tcd_nunits = 1;
+
+ spin_unlock_irqrestore(&mchan->lock, flags);
+
+ return 0;
+
+ default:
+ /* Unknown command */
+ break;
+ }
+
+ return -ENXIO;
+}
+