Index: sys/dev/mmc/mmcreg.h
===================================================================
--- sys/dev/mmc/mmcreg.h
+++ sys/dev/mmc/mmcreg.h
@@ -190,6 +190,8 @@
 
 struct mmc_data {
 	size_t len;		/* size of the data */
+	size_t block_size;      /* block size for CMD53 */
+	size_t block_count;     /* block count for CMD53 */
 	size_t xfer_len;
 	void *data;		/* data buffer */
 	uint32_t	flags;
@@ -197,6 +199,7 @@
 #define	MMC_DATA_READ	(1UL << 1)
 #define	MMC_DATA_STREAM	(1UL << 2)
 #define	MMC_DATA_MULTI	(1UL << 3)
+#define MMC_DATA_BLOCK_SIZE (1UL << 4)
 	struct mmc_request *mrq;
 };