mmc: sdhci: add quirks for be to le byte swapping

Some controller as the ColdFire eshdc may require an endianness
byte swap, because DMA read endianness is not configurable.

Facilitate using the bounce buffer for this by adding
->copy_to_bounce_buffer().
Signed-off-by: Angelo Dureghello <angelo.dureghello@timesys.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200518191742.1251440-2-angelo.dureghello@timesys.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -637,9 +637,13 @@ static int sdhci_pre_dma_transfer(struct sdhci_host *host,
 		}
 		if (mmc_get_dma_dir(data) == DMA_TO_DEVICE) {
 			/* Copy the data to the bounce buffer */
-			sg_copy_to_buffer(data->sg, data->sg_len,
-					  host->bounce_buffer,
-					  length);
+			if (host->ops->copy_to_bounce_buffer) {
+				host->ops->copy_to_bounce_buffer(host,
+								 data, length);
+			} else {
+				sg_copy_to_buffer(data->sg, data->sg_len,
+						  host->bounce_buffer, length);
+			}
 		}
 		/* Switch ownership to the DMA */
 		dma_sync_single_for_device(host->mmc->parent,

drivers/mmc/host/sdhci.h

@@ -645,6 +645,9 @@ struct sdhci_ops {
 	void	(*voltage_switch)(struct sdhci_host *host);
 	void	(*adma_write_desc)(struct sdhci_host *host, void **desc,
 				   dma_addr_t addr, int len, unsigned int cmd);
+	void	(*copy_to_bounce_buffer)(struct sdhci_host *host,
+					 struct mmc_data *data,
+					 unsigned int length);
 	void	(*request_done)(struct sdhci_host *host,
 				struct mmc_request *mrq);
 };