spi: Save current RX and TX DMA devices

Save the current RX and TX DMA devices to avoid having to duplicate the
logic to pick them, since we'll need access to them in some more
functions to fix a bug in the cache handling.
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Link: https://lore.kernel.org/r/20220927112117.77599-2-vincent.whitchurch@axis.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -1147,6 +1147,8 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
 		}
 	}
 
+	ctlr->cur_rx_dma_dev = rx_dev;
+	ctlr->cur_tx_dma_dev = tx_dev;
 	ctlr->cur_msg_mapped = true;
 
 	return 0;
@@ -1154,26 +1156,13 @@ static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
 
 static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg)
 {
+	struct device *rx_dev = ctlr->cur_rx_dma_dev;
+	struct device *tx_dev = ctlr->cur_tx_dma_dev;
 	struct spi_transfer *xfer;
-	struct device *tx_dev, *rx_dev;
 
 	if (!ctlr->cur_msg_mapped || !ctlr->can_dma)
 		return 0;
 
-	if (ctlr->dma_tx)
-		tx_dev = ctlr->dma_tx->device->dev;
-	else if (ctlr->dma_map_dev)
-		tx_dev = ctlr->dma_map_dev;
-	else
-		tx_dev = ctlr->dev.parent;
-
-	if (ctlr->dma_rx)
-		rx_dev = ctlr->dma_rx->device->dev;
-	else if (ctlr->dma_map_dev)
-		rx_dev = ctlr->dma_map_dev;
-	else
-		rx_dev = ctlr->dev.parent;
-
 	list_for_each_entry(xfer, &msg->transfers, transfer_list) {
 		if (!ctlr->can_dma(ctlr, msg->spi, xfer))
 			continue;

include/linux/spi/spi.h

@@ -378,6 +378,8 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch
  * @cleanup: frees controller-specific state
  * @can_dma: determine whether this controller supports DMA
  * @dma_map_dev: device which can be used for DMA mapping
+ * @cur_rx_dma_dev: device which is currently used for RX DMA mapping
+ * @cur_tx_dma_dev: device which is currently used for TX DMA mapping
  * @queued: whether this controller is providing an internal message queue
  * @kworker: pointer to thread struct for message pump
  * @pump_messages: work struct for scheduling work to the message pump
@@ -609,6 +611,8 @@ struct spi_controller {
 					   struct spi_device *spi,
 					   struct spi_transfer *xfer);
 	struct device *dma_map_dev;
+	struct device *cur_rx_dma_dev;
+	struct device *cur_tx_dma_dev;
 
 	/*
 	 * These hooks are for drivers that want to use the generic