+static struct dma_chan *sci_request_dma_chan(struct uart_port *port,
+ enum dma_transfer_direction dir,
+ unsigned int id)
+{
+ dma_cap_mask_t mask;
+ struct dma_chan *chan;
+ struct dma_slave_config cfg;
+ int ret;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
+
+ chan = dma_request_slave_channel_compat(mask, shdma_chan_filter,
+ (void *)(unsigned long)id, port->dev,
+ dir == DMA_MEM_TO_DEV ? "tx" : "rx");
+ if (!chan) {
+ dev_warn(port->dev,
+ "dma_request_slave_channel_compat failed\n");
+ return NULL;
+ }
+
+ memset(&cfg, 0, sizeof(cfg));
+ cfg.direction = dir;
+ if (dir == DMA_MEM_TO_DEV) {
+ cfg.dst_addr = port->mapbase +
+ (sci_getreg(port, SCxTDR)->offset << port->regshift);
+ cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ } else {
+ cfg.src_addr = port->mapbase +
+ (sci_getreg(port, SCxRDR)->offset << port->regshift);
+ cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ }
+
+ ret = dmaengine_slave_config(chan, &cfg);
+ if (ret) {
+ dev_warn(port->dev, "dmaengine_slave_config failed %d\n", ret);
+ dma_release_channel(chan);
+ return NULL;
+ }
+
+ return chan;
+}
+