[PATCH 4/4] mmc: sdhci: Add DMA memory boundary workaround

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DMA memory cannot cross specific boundary for some SDHCI controller,
such as DesignWare SDHCI controller. Add DMA memory boundary dt
property and workaround the limitation.

Signed-off-by: Jun Nie <jun.nie@xxxxxxxxxx>
---
 drivers/mmc/host/sdhci.c | 20 +++++++++++++++++++-
 drivers/mmc/host/sdhci.h |  1 +
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index d8a6c1c91448..56c53fbadd9d 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -763,9 +763,25 @@ static void sdhci_adma_table_pre(struct sdhci_host *host,
 		BUG_ON(len > 65536);
 
 		/* tran, valid */
-		if (len)
+		if (len) {
+			unsigned int boundary = host->dma_mem_boundary;
+			/*
+			 * work around for buffer across mem boundary, split
+			 * the buffer.
+			 */
+			if (boundary &&
+			    ((addr & (boundary - 1)) + len) > boundary) {
+				offset = boundary - (addr & (boundary - 1));
+				__sdhci_adma_write_desc(host, &desc,
+							addr, offset,
+							ADMA2_TRAN_VALID);
+				addr += offset;
+				len -= offset;
+			}
+
 			__sdhci_adma_write_desc(host, &desc, addr, len,
 						ADMA2_TRAN_VALID);
+		}
 
 		/*
 		 * If this triggers then we have a calculation bug
@@ -3634,6 +3650,8 @@ void __sdhci_read_caps(struct sdhci_host *host, const u16 *ver,
 			     "sdhci-caps-mask", &dt_caps_mask);
 	of_property_read_u64(mmc_dev(host->mmc)->of_node,
 			     "sdhci-caps", &dt_caps);
+	of_property_read_u32(mmc_dev(host->mmc)->of_node,
+			     "sdhci-dma-mem-boundary", &host->dma_mem_boundary);
 
 	if (of_property_read_u32(mmc_dev(host->mmc)->of_node,
 				 "sdhci-ctrl-hs400", &host->sdhci_ctrl_hs400))
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index cac4d819f62c..954ac08c4fb0 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -608,6 +608,7 @@ struct sdhci_host {
 
 	/* SDHCI_CTRL_HS400 value */
 	u32			sdhci_ctrl_hs400;
+	u32			dma_mem_boundary;
 
 	unsigned long private[0] ____cacheline_aligned;
 };
-- 
2.17.1




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