dm: block: Adjust device calls to go through helpers function

To ease conversion to driver model, add helper functions which deal with
calling each block device method. With driver model we can reimplement these
functions with the same arguments.

Use inline functions to avoid increasing code size on some boards.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Stephen Warren <swarren@nvidia.com>
diff --git a/cmd/disk.c b/cmd/disk.c
index 27ed115..e0219f8 100644
--- a/cmd/disk.c
+++ b/cmd/disk.c
@@ -56,7 +56,7 @@
 	      ", Block Size: %ld\n",
 	      info.start, info.size, info.blksz);
 
-	if (dev_desc->block_read(dev_desc, info.start, 1, (ulong *)addr) != 1) {
+	if (blk_dread(dev_desc, info.start, 1, (ulong *)addr) != 1) {
 		printf("** Read error on %d:%d\n", dev, part);
 		bootstage_error(BOOTSTAGE_ID_IDE_PART_READ);
 		return 1;
@@ -100,8 +100,8 @@
 	cnt /= info.blksz;
 	cnt -= 1;
 
-	if (dev_desc->block_read(dev_desc, info.start + 1, cnt,
-				 (ulong *)(addr + info.blksz)) != cnt) {
+	if (blk_dread(dev_desc, info.start + 1, cnt,
+		      (ulong *)(addr + info.blksz)) != cnt) {
 		printf("** Read error on %d:%d\n", dev, part);
 		bootstage_error(BOOTSTAGE_ID_IDE_READ);
 		return 1;
diff --git a/cmd/ide.c b/cmd/ide.c
index dfd5548..c4c08c8 100644
--- a/cmd/ide.c
+++ b/cmd/ide.c
@@ -10,6 +10,7 @@
  */
 
 #include <common.h>
+#include <blk.h>
 #include <config.h>
 #include <watchdog.h>
 #include <command.h>
@@ -203,8 +204,7 @@
 #endif
 
 			dev_desc = &ide_dev_desc[curr_device];
-			n = dev_desc->block_read(dev_desc, blk, cnt,
-						 (ulong *)addr);
+			n = blk_dread(dev_desc, blk, cnt, (ulong *)addr);
 			/* flush cache after read */
 			flush_cache(addr,
 				    cnt * ide_dev_desc[curr_device].blksz);
diff --git a/cmd/read.c b/cmd/read.c
index f8d766a..61d8ce7 100644
--- a/cmd/read.c
+++ b/cmd/read.c
@@ -66,7 +66,7 @@
 		return 1;
 	}
 
-	if (dev_desc->block_read(dev_desc, offset + blk, cnt, addr) < 0) {
+	if (blk_read(dev_desc, offset + blk, cnt, addr) < 0) {
 		printf("Error reading blocks\n");
 		return 1;
 	}
diff --git a/cmd/usb.c b/cmd/usb.c
index 53fd6ad..9ed5dc6 100644
--- a/cmd/usb.c
+++ b/cmd/usb.c
@@ -759,8 +759,7 @@
 			printf("\nUSB read: device %d block # %ld, count %ld"
 				" ... ", usb_stor_curr_dev, blk, cnt);
 			stor_dev = usb_stor_get_dev(usb_stor_curr_dev);
-			n = stor_dev->block_read(stor_dev, blk, cnt,
-						 (ulong *)addr);
+			n = blk_dread(stor_dev, blk, cnt, (ulong *)addr);
 			printf("%ld blocks read: %s\n", n,
 				(n == cnt) ? "OK" : "ERROR");
 			if (n == cnt)
@@ -781,8 +780,7 @@
 			printf("\nUSB write: device %d block # %ld, count %ld"
 				" ... ", usb_stor_curr_dev, blk, cnt);
 			stor_dev = usb_stor_get_dev(usb_stor_curr_dev);
-			n = stor_dev->block_write(stor_dev, blk, cnt,
-						(ulong *)addr);
+			n = blk_dwrite(stor_dev, blk, cnt, (ulong *)addr);
 			printf("%ld blocks write: %s\n", n,
 				(n == cnt) ? "OK" : "ERROR");
 			if (n == cnt)
diff --git a/common/fb_mmc.c b/common/fb_mmc.c
index da7949f..e3abcc8 100644
--- a/common/fb_mmc.c
+++ b/common/fb_mmc.c
@@ -6,6 +6,7 @@
 
 #include <config.h>
 #include <common.h>
+#include <blk.h>
 #include <errno.h>
 #include <fastboot.h>
 #include <fb_mmc.h>
@@ -58,7 +59,7 @@
 	struct blk_desc *dev_desc = sparse->dev_desc;
 	int ret;
 
-	ret = dev_desc->block_write(dev_desc, offset, size, data);
+	ret = blk_dwrite(dev_desc, offset, size, data);
 	if (!ret)
 		return -EIO;
 
@@ -84,7 +85,7 @@
 
 	puts("Flashing Raw Image\n");
 
-	blks = dev_desc->block_write(dev_desc, info->start, blkcnt, buffer);
+	blks = blk_dwrite(dev_desc, info->start, blkcnt, buffer);
 	if (blks != blkcnt) {
 		error("failed writing to device %d\n", dev_desc->devnum);
 		fastboot_fail(response_str, "failed writing to device");
diff --git a/disk/part_amiga.c b/disk/part_amiga.c
index d323b4b..4a67689 100644
--- a/disk/part_amiga.c
+++ b/disk/part_amiga.c
@@ -140,7 +140,7 @@
 
     for (i=0; i<limit; i++)
     {
-	ulong res = dev_desc->block_read(dev_desc, i, 1, (ulong *)block_buffer);
+	ulong res = blk_dread(dev_desc, i, 1, (ulong *)block_buffer);
 	if (res == 1)
 	{
 	    struct rigid_disk_block *trdb = (struct rigid_disk_block *)block_buffer;
@@ -182,7 +182,7 @@
 
     for (i = 0; i < limit; i++)
     {
-	ulong res = dev_desc->block_read(dev_desc, i, 1, (ulong *)block_buffer);
+	ulong res = blk_dread(dev_desc, i, 1, (ulong *)block_buffer);
 	if (res == 1)
 	{
 	    struct bootcode_block *boot = (struct bootcode_block *)block_buffer;
@@ -258,8 +258,7 @@
 
     while (block != 0xFFFFFFFF)
     {
-	ulong res = dev_desc->block_read(dev_desc, block, 1,
-					 (ulong *)block_buffer);
+	ulong res = blk_dread(dev_desc, block, 1, (ulong *)block_buffer);
 	if (res == 1)
 	{
 	    p = (struct partition_block *)block_buffer;
@@ -355,7 +354,7 @@
 
 	PRINTF("Trying to load block #0x%X\n", block);
 
-	res = dev_desc->block_read(dev_desc, block, 1, (ulong *)block_buffer);
+	res = blk_dread(dev_desc, block, 1, (ulong *)block_buffer);
 	if (res == 1)
 	{
 	    p = (struct partition_block *)block_buffer;
diff --git a/disk/part_dos.c b/disk/part_dos.c
index 5f8d949..0ed1374 100644
--- a/disk/part_dos.c
+++ b/disk/part_dos.c
@@ -91,7 +91,7 @@
 {
 	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, buffer, dev_desc->blksz);
 
-	if (dev_desc->block_read(dev_desc, 0, 1, (ulong *)buffer) != 1)
+	if (blk_dread(dev_desc, 0, 1, (ulong *)buffer) != 1)
 		return -1;
 
 	if (test_block_type(buffer) != DOS_MBR)
@@ -111,8 +111,7 @@
 	dos_partition_t *pt;
 	int i;
 
-	if (dev_desc->block_read(dev_desc, ext_part_sector, 1,
-				 (ulong *)buffer) != 1) {
+	if (blk_dread(dev_desc, ext_part_sector, 1, (ulong *)buffer) != 1) {
 		printf ("** Can't read partition table on %d:" LBAFU " **\n",
 			dev_desc->devnum, ext_part_sector);
 		return;
@@ -177,8 +176,7 @@
 	int i;
 	int dos_type;
 
-	if (dev_desc->block_read(dev_desc, ext_part_sector, 1,
-				 (ulong *)buffer) != 1) {
+	if (blk_dread(dev_desc, ext_part_sector, 1, (ulong *)buffer) != 1) {
 		printf ("** Can't read partition table on %d:" LBAFU " **\n",
 			dev_desc->devnum, ext_part_sector);
 		return -1;
diff --git a/disk/part_efi.c b/disk/part_efi.c
index ae8cd7e..b20907b 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -324,7 +324,7 @@
 	ALLOC_CACHE_ALIGN_BUFFER_PAD(legacy_mbr, legacymbr, 1, dev_desc->blksz);
 
 	/* Read legacy MBR from block 0 and validate it */
-	if ((dev_desc->block_read(dev_desc, 0, 1, (ulong *)legacymbr) != 1)
+	if ((blk_dread(dev_desc, 0, 1, (ulong *)legacymbr) != 1)
 		|| (is_pmbr_valid(legacymbr) != 1)) {
 		return -1;
 	}
@@ -354,7 +354,7 @@
 	p_mbr->partition_record[0].nr_sects = (u32) dev_desc->lba - 1;
 
 	/* Write MBR sector to the MMC device */
-	if (dev_desc->block_write(dev_desc, 0, 1, p_mbr) != 1) {
+	if (blk_dwrite(dev_desc, 0, 1, p_mbr) != 1) {
 		printf("** Can't write to device %d **\n",
 			dev_desc->devnum);
 		return -1;
@@ -386,24 +386,21 @@
 	gpt_h->header_crc32 = cpu_to_le32(calc_crc32);
 
 	/* Write the First GPT to the block right after the Legacy MBR */
-	if (dev_desc->block_write(dev_desc, 1, 1, gpt_h) != 1)
+	if (blk_dwrite(dev_desc, 1, 1, gpt_h) != 1)
 		goto err;
 
-	if (dev_desc->block_write(dev_desc, 2, pte_blk_cnt, gpt_e)
+	if (blk_dwrite(dev_desc, 2, pte_blk_cnt, gpt_e)
 	    != pte_blk_cnt)
 		goto err;
 
 	prepare_backup_gpt_header(gpt_h);
 
-	if (dev_desc->block_write(dev_desc,
-				  (lbaint_t)le64_to_cpu(gpt_h->last_usable_lba)
-				  + 1,
-				  pte_blk_cnt, gpt_e) != pte_blk_cnt)
+	if (blk_dwrite(dev_desc, (lbaint_t)le64_to_cpu(gpt_h->last_usable_lba)
+		       + 1, pte_blk_cnt, gpt_e) != pte_blk_cnt)
 		goto err;
 
-	if (dev_desc->block_write(dev_desc,
-				  (lbaint_t)le64_to_cpu(gpt_h->my_lba), 1,
-				  gpt_h) != 1)
+	if (blk_dwrite(dev_desc, (lbaint_t)le64_to_cpu(gpt_h->my_lba), 1,
+		       gpt_h) != 1)
 		goto err;
 
 	debug("GPT successfully written to block device!\n");
@@ -739,7 +736,7 @@
 	/* write MBR */
 	lba = 0;	/* MBR is always at 0 */
 	cnt = 1;	/* MBR (1 block) */
-	if (dev_desc->block_write(dev_desc, lba, cnt, buf) != cnt) {
+	if (blk_dwrite(dev_desc, lba, cnt, buf) != cnt) {
 		printf("%s: failed writing '%s' (%d blks at 0x" LBAF ")\n",
 		       __func__, "MBR", cnt, lba);
 		return 1;
@@ -748,7 +745,7 @@
 	/* write Primary GPT */
 	lba = GPT_PRIMARY_PARTITION_TABLE_LBA;
 	cnt = 1;	/* GPT Header (1 block) */
-	if (dev_desc->block_write(dev_desc, lba, cnt, gpt_h) != cnt) {
+	if (blk_dwrite(dev_desc, lba, cnt, gpt_h) != cnt) {
 		printf("%s: failed writing '%s' (%d blks at 0x" LBAF ")\n",
 		       __func__, "Primary GPT Header", cnt, lba);
 		return 1;
@@ -756,7 +753,7 @@
 
 	lba = le64_to_cpu(gpt_h->partition_entry_lba);
 	cnt = gpt_e_blk_cnt;
-	if (dev_desc->block_write(dev_desc, lba, cnt, gpt_e) != cnt) {
+	if (blk_dwrite(dev_desc, lba, cnt, gpt_e) != cnt) {
 		printf("%s: failed writing '%s' (%d blks at 0x" LBAF ")\n",
 		       __func__, "Primary GPT Entries", cnt, lba);
 		return 1;
@@ -767,7 +764,7 @@
 	/* write Backup GPT */
 	lba = le64_to_cpu(gpt_h->partition_entry_lba);
 	cnt = gpt_e_blk_cnt;
-	if (dev_desc->block_write(dev_desc, lba, cnt, gpt_e) != cnt) {
+	if (blk_dwrite(dev_desc, lba, cnt, gpt_e) != cnt) {
 		printf("%s: failed writing '%s' (%d blks at 0x" LBAF ")\n",
 		       __func__, "Backup GPT Entries", cnt, lba);
 		return 1;
@@ -775,7 +772,7 @@
 
 	lba = le64_to_cpu(gpt_h->my_lba);
 	cnt = 1;	/* GPT Header (1 block) */
-	if (dev_desc->block_write(dev_desc, lba, cnt, gpt_h) != cnt) {
+	if (blk_dwrite(dev_desc, lba, cnt, gpt_h) != cnt) {
 		printf("%s: failed writing '%s' (%d blks at 0x" LBAF ")\n",
 		       __func__, "Backup GPT Header", cnt, lba);
 		return 1;
@@ -845,7 +842,7 @@
 	}
 
 	/* Read GPT Header from device */
-	if (dev_desc->block_read(dev_desc, (lbaint_t)lba, 1, pgpt_head) != 1) {
+	if (blk_dread(dev_desc, (lbaint_t)lba, 1, pgpt_head) != 1) {
 		printf("*** ERROR: Can't read GPT header ***\n");
 		return 0;
 	}
@@ -913,8 +910,7 @@
 	/* Read GPT Entries from device */
 	blk = le64_to_cpu(pgpt_head->partition_entry_lba);
 	blk_cnt = BLOCK_CNT(count, dev_desc);
-	if (dev_desc->block_read(dev_desc, blk, (lbaint_t)blk_cnt, pte)
-	    != blk_cnt) {
+	if (blk_dread(dev_desc, blk, (lbaint_t)blk_cnt, pte) != blk_cnt) {
 		printf("*** ERROR: Can't read GPT Entries ***\n");
 		free(pte);
 		return NULL;
diff --git a/disk/part_iso.c b/disk/part_iso.c
index c78ae21..76eab39 100644
--- a/disk/part_iso.c
+++ b/disk/part_iso.c
@@ -63,7 +63,7 @@
 
 	/* the first sector (sector 0x10) must be a primary volume desc */
 	blkaddr=PVD_OFFSET;
-	if (dev_desc->block_read(dev_desc, PVD_OFFSET, 1, (ulong *)tmpbuf) != 1)
+	if (blk_dread(dev_desc, PVD_OFFSET, 1, (ulong *)tmpbuf) != 1)
 		return -1;
 	if(ppr->desctype!=0x01) {
 		if(verb)
@@ -85,7 +85,7 @@
 	PRINTF(" Lastsect:%08lx\n",lastsect);
 	for(i=blkaddr;i<lastsect;i++) {
 		PRINTF("Reading block %d\n", i);
-		if (dev_desc->block_read(dev_desc, i, 1, (ulong *)tmpbuf) != 1)
+		if (blk_dread(dev_desc, i, 1, (ulong *)tmpbuf) != 1)
 			return -1;
 		if(ppr->desctype==0x00)
 			break; /* boot entry found */
@@ -105,7 +105,7 @@
 	}
 	bootaddr=le32_to_int(pbr->pointer);
 	PRINTF(" Boot Entry at: %08lX\n",bootaddr);
-	if (dev_desc->block_read(dev_desc, bootaddr, 1, (ulong *)tmpbuf) != 1) {
+	if (blk_dread(dev_desc, bootaddr, 1, (ulong *)tmpbuf) != 1) {
 		if(verb)
 			printf ("** Can't read Boot Entry at %lX on %d:%d **\n",
 				bootaddr, dev_desc->devnum, part_num);
diff --git a/disk/part_mac.c b/disk/part_mac.c
index 07bbc19..ce57b57 100644
--- a/disk/part_mac.c
+++ b/disk/part_mac.c
@@ -53,8 +53,7 @@
 
 	n = 1;	/* assuming at least one partition */
 	for (i=1; i<=n; ++i) {
-		if ((dev_desc->block_read(dev_desc, i, 1,
-					  (ulong *)mpart) != 1) ||
+		if ((blk_dread(dev_desc, i, 1, (ulong *)mpart) != 1) ||
 		    (mpart->signature != MAC_PARTITION_MAGIC) ) {
 			return (-1);
 		}
@@ -106,7 +105,7 @@
 		char c;
 
 		printf ("%4ld: ", i);
-		if (dev_desc->block_read(dev_desc, i, 1, (ulong *)mpart) != 1) {
+		if (blk_dread(dev_desc, i, 1, (ulong *)mpart) != 1) {
 			printf ("** Can't read Partition Map on %d:%ld **\n",
 				dev_desc->devnum, i);
 			return;
@@ -153,7 +152,7 @@
 static int part_mac_read_ddb(struct blk_desc *dev_desc,
 			     mac_driver_desc_t *ddb_p)
 {
-	if (dev_desc->block_read(dev_desc, 0, 1, (ulong *)ddb_p) != 1) {
+	if (blk_dread(dev_desc, 0, 1, (ulong *)ddb_p) != 1) {
 		printf ("** Can't read Driver Desriptor Block **\n");
 		return (-1);
 	}
@@ -182,7 +181,7 @@
 		 * partition 1 first since this is the only way to
 		 * know how many partitions we have.
 		 */
-		if (dev_desc->block_read(dev_desc, n, 1, (ulong *)pdb_p) != 1) {
+		if (blk_dread(dev_desc, n, 1, (ulong *)pdb_p) != 1) {
 			printf ("** Can't read Partition Map on %d:%d **\n",
 				dev_desc->devnum, n);
 			return (-1);
diff --git a/fs/ext4/dev.c b/fs/ext4/dev.c
index 3eef66f..ee84d3f 100644
--- a/fs/ext4/dev.c
+++ b/fs/ext4/dev.c
@@ -24,6 +24,7 @@
  */
 
 #include <common.h>
+#include <blk.h>
 #include <config.h>
 #include <memalign.h>
 #include <ext4fs.h>
@@ -76,9 +77,8 @@
 	if (byte_offset != 0) {
 		int readlen;
 		/* read first part which isn't aligned with start of sector */
-		if (ext4fs_blk_desc->block_read(ext4fs_blk_desc,
-						part_info->start + sector,
-						1, (void *)sec_buf) != 1) {
+		if (blk_dread(ext4fs_blk_desc, part_info->start + sector, 1,
+			      (void *)sec_buf) != 1) {
 			printf(" ** ext2fs_devread() read error **\n");
 			return 0;
 		}
@@ -100,17 +100,15 @@
 		ALLOC_CACHE_ALIGN_BUFFER(u8, p, ext4fs_blk_desc->blksz);
 
 		block_len = ext4fs_blk_desc->blksz;
-		ext4fs_blk_desc->block_read(ext4fs_blk_desc,
-						  part_info->start + sector,
-						  1, (void *)p);
+		blk_dread(ext4fs_blk_desc, part_info->start + sector, 1,
+			  (void *)p);
 		memcpy(buf, p, byte_len);
 		return 1;
 	}
 
-	if (ext4fs_blk_desc->block_read(ext4fs_blk_desc,
-					part_info->start + sector,
-					block_len >> log2blksz, (void *)buf)
-				!= block_len >> log2blksz) {
+	if (blk_dread(ext4fs_blk_desc, part_info->start + sector,
+		      block_len >> log2blksz, (void *)buf) !=
+			block_len >> log2blksz) {
 		printf(" ** %s read error - block\n", __func__);
 		return 0;
 	}
@@ -121,9 +119,8 @@
 
 	if (byte_len != 0) {
 		/* read rest of data which are not in whole sector */
-		if (ext4fs_blk_desc->block_read(ext4fs_blk_desc,
-						part_info->start + sector,
-						1, (void *)sec_buf) != 1) {
+		if (blk_dread(ext4fs_blk_desc, part_info->start + sector, 1,
+			      (void *)sec_buf) != 1) {
 			printf("* %s read error - last part\n", __func__);
 			return 0;
 		}
diff --git a/fs/ext4/ext4_common.c b/fs/ext4/ext4_common.c
index 294a46e..84fba76 100644
--- a/fs/ext4/ext4_common.c
+++ b/fs/ext4/ext4_common.c
@@ -81,29 +81,20 @@
 	}
 
 	if (remainder) {
-		if (fs->dev_desc->block_read) {
-			fs->dev_desc->block_read(fs->dev_desc,
-						 startblock, 1, sec_buf);
-			temp_ptr = sec_buf;
-			memcpy((temp_ptr + remainder),
-			       (unsigned char *)buf, size);
-			fs->dev_desc->block_write(fs->dev_desc,
-						  startblock, 1, sec_buf);
-		}
+		blk_dread(fs->dev_desc, startblock, 1, sec_buf);
+		temp_ptr = sec_buf;
+		memcpy((temp_ptr + remainder), (unsigned char *)buf, size);
+		blk_dwrite(fs->dev_desc, startblock, 1, sec_buf);
 	} else {
 		if (size >> log2blksz != 0) {
-			fs->dev_desc->block_write(fs->dev_desc,
-						  startblock,
-						  size >> log2blksz,
-						  (unsigned long *)buf);
+			blk_dwrite(fs->dev_desc, startblock, size >> log2blksz,
+				   (unsigned long *)buf);
 		} else {
-			fs->dev_desc->block_read(fs->dev_desc,
-						 startblock, 1, sec_buf);
+			blk_dread(fs->dev_desc, startblock, 1, sec_buf);
 			temp_ptr = sec_buf;
 			memcpy(temp_ptr, buf, size);
-			fs->dev_desc->block_write(fs->dev_desc,
-						  startblock, 1,
-						  (unsigned long *)sec_buf);
+			blk_dwrite(fs->dev_desc, startblock, 1,
+				   (unsigned long *)sec_buf);
 		}
 	}
 }
diff --git a/fs/fat/fat.c b/fs/fat/fat.c
index f87ddd7..600a90e 100644
--- a/fs/fat/fat.c
+++ b/fs/fat/fat.c
@@ -10,6 +10,7 @@
  */
 
 #include <common.h>
+#include <blk.h>
 #include <config.h>
 #include <exports.h>
 #include <fat.h>
@@ -48,11 +49,10 @@
 {
 	ulong ret;
 
-	if (!cur_dev || !cur_dev->block_read)
+	if (!cur_dev)
 		return -1;
 
-	ret = cur_dev->block_read(cur_dev, cur_part_info.start + block,
-				  nr_blocks, buf);
+	ret = blk_dread(cur_dev, cur_part_info.start + block, nr_blocks, buf);
 
 	if (nr_blocks && ret == 0)
 		return -1;
diff --git a/fs/fat/fat_write.c b/fs/fat/fat_write.c
index 5ed324c..baa85ec 100644
--- a/fs/fat/fat_write.c
+++ b/fs/fat/fat_write.c
@@ -32,7 +32,7 @@
 {
 	ulong ret;
 
-	if (!cur_dev || !cur_dev->block_write)
+	if (!cur_dev)
 		return -1;
 
 	if (cur_part_info.start + block + nr_blocks >
@@ -41,8 +41,7 @@
 		return -1;
 	}
 
-	ret = cur_dev->block_write(cur_dev, cur_part_info.start + block,
-				   nr_blocks, buf);
+	ret = blk_dwrite(cur_dev, cur_part_info.start + block, nr_blocks, buf);
 	if (nr_blocks && ret == 0)
 		return -1;
 
diff --git a/include/blk.h b/include/blk.h
index 9c54842..7b2e5e2 100644
--- a/include/blk.h
+++ b/include/blk.h
@@ -71,4 +71,33 @@
 #define PAD_TO_BLOCKSIZE(size, blk_desc) \
 	(PAD_SIZE(size, blk_desc->blksz))
 
+/*
+ * These functions should take struct udevice instead of struct blk_desc,
+ * but this is convenient for migration to driver model. Add a 'd' prefix
+ * to the function operations, so that blk_read(), etc. can be reserved for
+ * functions with the correct arguments.
+ */
+static inline ulong blk_dread(struct blk_desc *block_dev, lbaint_t start,
+			      lbaint_t blkcnt, void *buffer)
+{
+	/*
+	 * We could check if block_read is NULL and return -ENOSYS. But this
+	 * bloats the code slightly (cause some board to fail to build), and
+	 * it would be an error to try an operation that does not exist.
+	 */
+	return block_dev->block_read(block_dev, start, blkcnt, buffer);
+}
+
+static inline ulong blk_dwrite(struct blk_desc *block_dev, lbaint_t start,
+			       lbaint_t blkcnt, const void *buffer)
+{
+	return block_dev->block_write(block_dev, start, blkcnt, buffer);
+}
+
+static inline ulong blk_derase(struct blk_desc *block_dev, lbaint_t start,
+			       lbaint_t blkcnt)
+{
+	return block_dev->block_erase(block_dev, start, blkcnt);
+}
+
 #endif
diff --git a/test/dm/usb.c b/test/dm/usb.c
index 0996185..2d20354 100644
--- a/test/dm/usb.c
+++ b/test/dm/usb.c
@@ -50,7 +50,7 @@
 	/* Read a few blocks and look for the string we expect */
 	ut_asserteq(512, dev_desc->blksz);
 	memset(cmp, '\0', sizeof(cmp));
-	ut_asserteq(2, dev_desc->block_read(dev_desc, 0, 2, cmp));
+	ut_asserteq(2, blk_dread(dev_desc, 0, 2, cmp));
 	ut_assertok(strcmp(cmp, "this is a test"));
 
 	return 0;