Index: dev/sdhci/sdhci.h
===================================================================
--- dev/sdhci/sdhci.h	(revision 246886)
+++ dev/sdhci/sdhci.h	(working copy)
@@ -224,8 +224,9 @@
 	device_t	dev;		/* Slot device */
 	u_char		num;		/* Slot number */
 	u_char		opt;		/* Slot options */
+#define SDHCI_HAVE_DMA			1
+#define SDHCI_PLATFORM_TRANSFER		2
 	u_char		version;
-#define SDHCI_HAVE_DMA		1
 	uint32_t	max_clk;	/* Max possible freq */
 	uint32_t	timeout_clk;	/* Timeout freq */
 	bus_dma_tag_t 	dmatag;
@@ -250,6 +251,7 @@
 #define CMD_STARTED		1
 #define STOP_STARTED		2
 #define SDHCI_USE_DMA		4	/* Use DMA for this req. */
+#define PLATFORM_DATA_STARTED	8	/* Data transfer is handled by platform */
 	struct mtx	mtx;		/* Slot mutex */
 };
 
@@ -257,6 +259,8 @@
 int sdhci_generic_write_ivar(device_t bus, device_t child, int which, uintptr_t value);
 int sdhci_init_slot(device_t dev, struct sdhci_slot *slot, int num);
 void sdhci_start_slot(struct sdhci_slot *slot);
+/* performs generic clean-up for platform transfers */
+void sdhci_finish_data(struct sdhci_slot *slot);
 int sdhci_cleanup_slot(struct sdhci_slot *slot);
 int sdhci_generic_suspend(struct sdhci_slot *slot);
 int sdhci_generic_resume(struct sdhci_slot *slot);
Index: dev/sdhci/sdhci_if.m
===================================================================
--- dev/sdhci/sdhci_if.m	(revision 246886)
+++ dev/sdhci/sdhci_if.m	(working copy)
@@ -131,6 +131,22 @@
 	bus_size_t		count;
 }
 
+METHOD int platform_will_handle {
+	device_t		brdev;
+	struct sdhci_slot	*slot;
+}
+
+METHOD void platform_start_transfer {
+	device_t		brdev;
+	struct sdhci_slot	*slot;
+	uint32_t		*intmask;
+}
+
+METHOD void platform_finish_transfer {
+	device_t		brdev;
+	struct sdhci_slot	*slot;
+}
+
 METHOD uint32_t min_freq {
 	device_t		brdev;
 	struct sdhci_slot	*slot;
Index: dev/sdhci/sdhci.c
===================================================================
--- dev/sdhci/sdhci.c	(revision 246891)
+++ dev/sdhci/sdhci.c	(working copy)
@@ -573,6 +573,13 @@
 	if (slot->quirks & SDHCI_QUIRK_FORCE_DMA)
 		slot->opt |= SDHCI_HAVE_DMA;
 
+	/* 
+	 * Use platform-provided transfer backend
+	 * with PIO as a fallback mechanism
+	 */
+	if (slot->opt & SDHCI_PLATFORM_TRANSFER)
+		slot->opt &= ~SDHCI_HAVE_DMA;
+
 	if (bootverbose || sdhci_debug) {
 		slot_printf(slot, "%uMHz%s 4bits%s%s%s %s\n",
 		    slot->max_clk / 1000000,
@@ -909,7 +916,7 @@
 	WR2(slot, SDHCI_BLOCK_COUNT, (data->len + 511) / 512);
 }
 
-static void
+void
 sdhci_finish_data(struct sdhci_slot *slot)
 {
 	struct mmc_data *data = slot->curcmd->data;
@@ -1102,13 +1109,23 @@
 	}
 	if (slot->curcmd->error) {
 		/* No need to continue after any error. */
-		sdhci_finish_data(slot);
+		if (slot->flags & PLATFORM_DATA_STARTED) {
+			slot->flags &= ~PLATFORM_DATA_STARTED;
+			SDHCI_PLATFORM_FINISH_TRANSFER(slot->bus, slot);
+		} else
+			sdhci_finish_data(slot);
 		return;
 	}
 
 	/* Handle PIO interrupt. */
-	if (intmask & (SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL))
-		sdhci_transfer_pio(slot);
+	if (intmask & (SDHCI_INT_DATA_AVAIL | SDHCI_INT_SPACE_AVAIL)) {
+		if ((slot->opt & SDHCI_PLATFORM_TRANSFER) && 
+		    SDHCI_PLATFORM_WILL_HANDLE(slot->bus, slot)) {
+			SDHCI_PLATFORM_START_TRANSFER(slot->bus, slot, &intmask);
+			slot->flags |= PLATFORM_DATA_STARTED;
+		} else
+			sdhci_transfer_pio(slot);
+	}
 	/* Handle DMA border. */
 	if (intmask & SDHCI_INT_DMA_END) {
 		struct mmc_data *data = slot->curcmd->data;
@@ -1147,8 +1164,13 @@
 		WR4(slot, SDHCI_DMA_ADDRESS, slot->paddr);
 	}
 	/* We have got all data. */
-	if (intmask & SDHCI_INT_DATA_END)
-		sdhci_finish_data(slot);
+	if (intmask & SDHCI_INT_DATA_END) {
+		if (slot->flags & PLATFORM_DATA_STARTED) {
+			slot->flags &= ~PLATFORM_DATA_STARTED;
+			SDHCI_PLATFORM_FINISH_TRANSFER(slot->bus, slot);
+		} else
+			sdhci_finish_data(slot);
+	}
 }
 
 static void