Patchwork [U-Boot,9/9] dfu: Support larger than memory transfers.

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Submitter Pantelis Antoniou
Date Nov. 30, 2012, 4:51 p.m.
Message ID <1354294293-2801-10-git-send-email-panto@antoniou-consulting.com>
Download mbox | patch
Permalink /patch/202999/
State Superseded
Delegated to: Marek Vasut
Headers show

Comments

Pantelis Antoniou - Nov. 30, 2012, 4:51 p.m.
We didn't support upload/download larger than available memory.
This is pretty bad when you have to update your root filesystem for
example.

This patch removes the limitation (and the crashes when you transfered
any file larger than 4MB).
On top of that reduces the huge dfu buffer from 4MB to just 64K, which
was over the top.

The sequence number is a 16 bit counter; make sure we
handle rollover correctly. This fixes the wrong transfers for
large (> 256MB) images.

Also utilize a variable to handle initialization, so that we
don't rely on just the counter sent by the host.

Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
---
 drivers/dfu/dfu.c     | 244 +++++++++++++++++++++++++++++++++++++++-----------
 drivers/dfu/dfu_mmc.c |  82 +++++++++++------
 include/dfu.h         |  21 ++++-
 3 files changed, 264 insertions(+), 83 deletions(-)
kasim ling - Jan. 3, 2013, 8:30 a.m.
Hi, Pantelis,
A little confusion about FAT fs write supporting,


On Sat, Dec 1, 2012 at 12:51 AM, Pantelis Antoniou
<panto@antoniou-consulting.com> wrote:
>
> We didn't support upload/download larger than available memory.
> This is pretty bad when you have to update your root filesystem for
> example.
>
> This patch removes the limitation (and the crashes when you transfered
> any file larger than 4MB).
> On top of that reduces the huge dfu buffer from 4MB to just 64K, which
> was over the top.
>
> The sequence number is a 16 bit counter; make sure we
> handle rollover correctly. This fixes the wrong transfers for
> large (> 256MB) images.
>
> Also utilize a variable to handle initialization, so that we
> don't rely on just the counter sent by the host.
>
> Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
> ---
>  drivers/dfu/dfu.c     | 244 +++++++++++++++++++++++++++++++++++++++-----------
>  drivers/dfu/dfu_mmc.c |  82 +++++++++++------
>  include/dfu.h         |  21 ++++-
>  3 files changed, 264 insertions(+), 83 deletions(-)

> diff --git a/drivers/dfu/dfu_mmc.c b/drivers/dfu/dfu_mmc.c
> index 083d745..29a2c2e 100644
> --- a/drivers/dfu/dfu_mmc.c
> +++ b/drivers/dfu/dfu_mmc.c
> @@ -22,6 +22,7 @@
>  #include <common.h>
>  #include <malloc.h>
>  #include <errno.h>
> +#include <div64.h>
>  #include <dfu.h>
>
>  enum dfu_mmc_op {
> @@ -30,35 +31,48 @@ enum dfu_mmc_op {
>  };
>
>  static int mmc_block_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
> -                       void *buf, long *len)
> +                       u64 offset, void *buf, long *len)
>  {
>         char cmd_buf[DFU_CMD_BUF_SIZE];
> +       u32 blk_start, blk_count;
>
> -       sprintf(cmd_buf, "mmc %s 0x%x %x %x",
> -               op == DFU_OP_READ ? "read" : "write",
> -               (unsigned int) buf,
> -               dfu->data.mmc.lba_start,
> -               dfu->data.mmc.lba_size);
> -
> -       if (op == DFU_OP_READ)
> +       /* if buf == NULL return total size of the area */
> +       if (buf == NULL) {
>                 *len = dfu->data.mmc.lba_blk_size * dfu->data.mmc.lba_size;
> +               return 0;
> +       }
> +
> +       blk_start = dfu->data.mmc.lba_start +
> +                       (u32)lldiv(offset, dfu->data.mmc.lba_blk_size);
> +       blk_count = *len / dfu->data.mmc.lba_blk_size;
> +       if (blk_start + blk_count >
> +                       dfu->data.mmc.lba_start + dfu->data.mmc.lba_size) {
> +               debug("%s: block_op out of bounds\n", __func__);
> +               return -1;
> +       }
> +
> +       sprintf(cmd_buf, "mmc %s %p %x %x",
> +               op == DFU_OP_READ ? "read" : "write",
> +                buf, blk_start, blk_count);
>
>         debug("%s: %s 0x%p\n", __func__, cmd_buf, cmd_buf);
>         return run_command(cmd_buf, 0);
>  }
>
> -static inline int mmc_block_write(struct dfu_entity *dfu, void *buf, long *len)
> +static inline int mmc_block_write(struct dfu_entity *dfu,
> +               u64 offset, void *buf, long *len)
>  {
> -       return mmc_block_op(DFU_OP_WRITE, dfu, buf, len);
> +       return mmc_block_op(DFU_OP_WRITE, dfu, offset, buf, len);
>  }
>
> -static inline int mmc_block_read(struct dfu_entity *dfu, void *buf, long *len)
> +static inline int mmc_block_read(struct dfu_entity *dfu,
> +               u64 offset, void *buf, long *len)
>  {
> -       return mmc_block_op(DFU_OP_READ, dfu, buf, len);
> +       return mmc_block_op(DFU_OP_READ, dfu, offset, buf, len);
>  }
>
>  static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
> -                       void *buf, long *len)
> +                       u64 offset, void *buf, long *len)
>  {
>         char cmd_buf[DFU_CMD_BUF_SIZE];
>         char *str_env;
> @@ -66,12 +80,17 @@ static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
>
>         switch (dfu->layout) {
>         case DFU_FS_FAT:
> -               sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx",
> +               sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx %llx",
>                         op == DFU_OP_READ ? "load" : "write",
>                         dfu->data.mmc.dev, dfu->data.mmc.part,
> -                       (unsigned int) buf, dfu->name, *len);
> +                       (unsigned int) buf, dfu->name, *len, offset);
Did you tested it on FAT partitions? According to do_fat_fswrite()
defined in common/cmd_fat.c, the "fatwrite" command does not support
"offset" argument.


Thanks,
Alex
Pantelis Antoniou - Jan. 4, 2013, 5:23 p.m.
Hi Kasim,

On Jan 3, 2013, at 10:30 AM, kasim ling wrote:

> Hi, Pantelis,
> A little confusion about FAT fs write supporting,
> 
> 
> On Sat, Dec 1, 2012 at 12:51 AM, Pantelis Antoniou
> <panto@antoniou-consulting.com> wrote:
>> 
>> We didn't support upload/download larger than available memory.
>> This is pretty bad when you have to update your root filesystem for
>> example.
>> 
>> This patch removes the limitation (and the crashes when you transfered
>> any file larger than 4MB).
>> On top of that reduces the huge dfu buffer from 4MB to just 64K, which
>> was over the top.
>> 
>> The sequence number is a 16 bit counter; make sure we
>> handle rollover correctly. This fixes the wrong transfers for
>> large (> 256MB) images.
>> 
>> Also utilize a variable to handle initialization, so that we
>> don't rely on just the counter sent by the host.
>> 
>> Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
>> ---
>> drivers/dfu/dfu.c     | 244 +++++++++++++++++++++++++++++++++++++++-----------
>> drivers/dfu/dfu_mmc.c |  82 +++++++++++------
>> include/dfu.h         |  21 ++++-
>> 3 files changed, 264 insertions(+), 83 deletions(-)
> 
>> diff --git a/drivers/dfu/dfu_mmc.c b/drivers/dfu/dfu_mmc.c
>> index 083d745..29a2c2e 100644
>> --- a/drivers/dfu/dfu_mmc.c
>> +++ b/drivers/dfu/dfu_mmc.c
>> @@ -22,6 +22,7 @@
>> #include <common.h>
>> #include <malloc.h>
>> #include <errno.h>
>> +#include <div64.h>
>> #include <dfu.h>
>> 
>> enum dfu_mmc_op {
>> @@ -30,35 +31,48 @@ enum dfu_mmc_op {
>> };
>> 
>> static int mmc_block_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
>> -                       void *buf, long *len)
>> +                       u64 offset, void *buf, long *len)
>> {
>>        char cmd_buf[DFU_CMD_BUF_SIZE];
>> +       u32 blk_start, blk_count;
>> 
>> -       sprintf(cmd_buf, "mmc %s 0x%x %x %x",
>> -               op == DFU_OP_READ ? "read" : "write",
>> -               (unsigned int) buf,
>> -               dfu->data.mmc.lba_start,
>> -               dfu->data.mmc.lba_size);
>> -
>> -       if (op == DFU_OP_READ)
>> +       /* if buf == NULL return total size of the area */
>> +       if (buf == NULL) {
>>                *len = dfu->data.mmc.lba_blk_size * dfu->data.mmc.lba_size;
>> +               return 0;
>> +       }
>> +
>> +       blk_start = dfu->data.mmc.lba_start +
>> +                       (u32)lldiv(offset, dfu->data.mmc.lba_blk_size);
>> +       blk_count = *len / dfu->data.mmc.lba_blk_size;
>> +       if (blk_start + blk_count >
>> +                       dfu->data.mmc.lba_start + dfu->data.mmc.lba_size) {
>> +               debug("%s: block_op out of bounds\n", __func__);
>> +               return -1;
>> +       }
>> +
>> +       sprintf(cmd_buf, "mmc %s %p %x %x",
>> +               op == DFU_OP_READ ? "read" : "write",
>> +                buf, blk_start, blk_count);
>> 
>>        debug("%s: %s 0x%p\n", __func__, cmd_buf, cmd_buf);
>>        return run_command(cmd_buf, 0);
>> }
>> 
>> -static inline int mmc_block_write(struct dfu_entity *dfu, void *buf, long *len)
>> +static inline int mmc_block_write(struct dfu_entity *dfu,
>> +               u64 offset, void *buf, long *len)
>> {
>> -       return mmc_block_op(DFU_OP_WRITE, dfu, buf, len);
>> +       return mmc_block_op(DFU_OP_WRITE, dfu, offset, buf, len);
>> }
>> 
>> -static inline int mmc_block_read(struct dfu_entity *dfu, void *buf, long *len)
>> +static inline int mmc_block_read(struct dfu_entity *dfu,
>> +               u64 offset, void *buf, long *len)
>> {
>> -       return mmc_block_op(DFU_OP_READ, dfu, buf, len);
>> +       return mmc_block_op(DFU_OP_READ, dfu, offset, buf, len);
>> }
>> 
>> static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
>> -                       void *buf, long *len)
>> +                       u64 offset, void *buf, long *len)
>> {
>>        char cmd_buf[DFU_CMD_BUF_SIZE];
>>        char *str_env;
>> @@ -66,12 +80,17 @@ static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
>> 
>>        switch (dfu->layout) {
>>        case DFU_FS_FAT:
>> -               sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx",
>> +               sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx %llx",
>>                        op == DFU_OP_READ ? "load" : "write",
>>                        dfu->data.mmc.dev, dfu->data.mmc.part,
>> -                       (unsigned int) buf, dfu->name, *len);
>> +                       (unsigned int) buf, dfu->name, *len, offset);
> Did you tested it on FAT partitions? According to do_fat_fswrite()
> defined in common/cmd_fat.c, the "fatwrite" command does not support
> "offset" argument.
> 

No I haven't had a use case either for fat or ext2/3/4.

So I guess it is as broken as it was before.
If you want to write to a file, make sure it's smaller than the
DFU buffer.

One of these days the file access functions must be fixed.
> 
> Thanks,
> Alex

Regards

-- Pantelis

Patch

diff --git a/drivers/dfu/dfu.c b/drivers/dfu/dfu.c
index e8477fb..fb9b417 100644
--- a/drivers/dfu/dfu.c
+++ b/drivers/dfu/dfu.c
@@ -44,90 +44,228 @@  static int dfu_find_alt_num(const char *s)
 static unsigned char __aligned(CONFIG_SYS_CACHELINE_SIZE)
 				     dfu_buf[DFU_DATA_BUF_SIZE];
 
+static int dfu_write_buffer_flush(struct dfu_entity *dfu)
+{
+	long w_size;
+	int ret;
+
+	/* flush size? */
+	w_size = dfu->i_buf - dfu->i_buf_start;
+	if (w_size == 0)
+		return 0;
+
+	/* update CRC32 */
+	dfu->crc = crc32(dfu->crc, dfu->i_buf_start, w_size);
+
+	ret = dfu->write_medium(dfu, dfu->offset, dfu->i_buf_start, &w_size);
+	if (ret)
+		debug("%s: Write error!\n", __func__);
+
+	/* point back */
+	dfu->i_buf = dfu->i_buf_start;
+
+	/* update offset */
+	dfu->offset += w_size;
+
+	puts("#");
+
+	return ret;
+}
+
 int dfu_write(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 {
-	static unsigned char *i_buf;
-	static int i_blk_seq_num;
-	long w_size = 0;
 	int ret = 0;
+	int tret;
+
+	debug("%s: name: %s buf: 0x%p size: 0x%x p_num: 0x%x "
+			"offset: 0x%llx bufoffset: 0x%x\n",
+	       __func__, dfu->name, buf, size, blk_seq_num, dfu->offset,
+	       dfu->i_buf - dfu->i_buf_start);
+
+	if (!dfu->inited) {
+		/* initial state */
+		dfu->crc = 0;
+		dfu->offset = 0;
+		dfu->i_blk_seq_num = 0;
+		dfu->i_buf_start = dfu_buf;
+		dfu->i_buf_end = dfu_buf + sizeof(dfu_buf);
+		dfu->i_buf = dfu->i_buf_start;
+
+		dfu->inited = 1;
+	}
 
-	debug("%s: name: %s buf: 0x%p size: 0x%x p_num: 0x%x i_buf: 0x%p\n",
-	       __func__, dfu->name, buf, size, blk_seq_num, i_buf);
+	if (dfu->i_blk_seq_num != blk_seq_num) {
+		printf("%s: Wrong sequence number! [%d] [%d]\n",
+		       __func__, dfu->i_blk_seq_num, blk_seq_num);
+		return -1;
+	}
 
-	if (blk_seq_num == 0) {
-		i_buf = dfu_buf;
-		i_blk_seq_num = 0;
+	/* DFU 1.1 standard says:
+	 * The wBlockNum field is a block sequence number. It increments each
+	 * time a block is transferred, wrapping to zero from 65,535. It is used
+	 * to provide useful context to the DFU loader in the device."
+	 *
+	 * This means that it's a 16 bit counter that roll-overs at
+	 * 0xffff -> 0x0000. By having a typical 4K transfer block
+	 * we roll-over at exactly 256MB. Not very fun to debug.
+	 *
+	 * Handling rollover, and having an inited variable,
+	 * makes things work.
+	 */
+
+	/* handle rollover */
+	dfu->i_blk_seq_num = (dfu->i_blk_seq_num + 1) & 0xffff;
+
+	/* flush buffer if overflow */
+	if ((dfu->i_buf + size) > dfu->i_buf_end) {
+		tret = dfu_write_buffer_flush(dfu);
+		if (ret == 0)
+			ret = tret;
 	}
 
-	if (i_blk_seq_num++ != blk_seq_num) {
-		printf("%s: Wrong sequence number! [%d] [%d]\n",
-		       __func__, i_blk_seq_num, blk_seq_num);
+	/* we should be in buffer now (if not then size too large) */
+	if ((dfu->i_buf + size) > dfu->i_buf_end) {
+		printf("%s: Wrong size! [%d] [%d] - %d\n",
+		       __func__, dfu->i_blk_seq_num, blk_seq_num, size);
 		return -1;
 	}
 
-	memcpy(i_buf, buf, size);
-	i_buf += size;
+	memcpy(dfu->i_buf, buf, size);
+	dfu->i_buf += size;
 
+	/* if end or if buffer full flush */
+	if (size == 0 || (dfu->i_buf + size) > dfu->i_buf_end) {
+		tret = dfu_write_buffer_flush(dfu);
+		if (ret == 0)
+			ret = tret;
+	}
+
+	/* end? */
 	if (size == 0) {
-		/* Integrity check (if needed) */
-		debug("%s: %s %d [B] CRC32: 0x%x\n", __func__, dfu->name,
-		       i_buf - dfu_buf, crc32(0, dfu_buf, i_buf - dfu_buf));
+		debug("%s: DFU complete CRC32: 0x%x\n", __func__, dfu->crc);
 
-		w_size = i_buf - dfu_buf;
-		ret = dfu->write_medium(dfu, dfu_buf, &w_size);
-		if (ret)
-			debug("%s: Write error!\n", __func__);
+		printf("\nDownload complete (CRC32 0x%04x)\n", dfu->crc);
+
+		/* clear everything */
+		dfu->crc = 0;
+		dfu->offset = 0;
+		dfu->i_blk_seq_num = 0;
+		dfu->i_buf_start = dfu_buf;
+		dfu->i_buf_end = dfu_buf + sizeof(dfu_buf);
+		dfu->i_buf = dfu->i_buf_start;
+
+		dfu->inited = 0;
 
-		i_blk_seq_num = 0;
-		i_buf = NULL;
-		return ret;
 	}
 
-	return ret;
+	return ret = 0 ? size : ret;
+}
+
+static int dfu_read_buffer_fill(struct dfu_entity *dfu, void *buf, int size)
+{
+	long chunk;
+	int ret, readn;
+
+	readn = 0;
+	while (size > 0) {
+
+		/* get chunk that can be read */
+		chunk = min(size, dfu->b_left);
+		/* consume */
+		if (chunk > 0) {
+			memcpy(buf, dfu->i_buf, chunk);
+			dfu->crc = crc32(dfu->crc, buf, chunk);
+			dfu->i_buf += chunk;
+			dfu->b_left -= chunk;
+			size -= chunk;
+			buf += chunk;
+			readn += chunk;
+		}
+
+		/* all done */
+		if (size > 0) {
+			/* no more to read */
+			if (dfu->r_left == 0)
+				break;
+
+			dfu->i_buf = dfu->i_buf_start;
+			dfu->b_left = dfu->i_buf_end - dfu->i_buf_start;
+
+			/* got to read, but buffer is empty */
+			if (dfu->b_left > dfu->r_left)
+				dfu->b_left = dfu->r_left;
+			ret = dfu->read_medium(dfu, dfu->offset, dfu->i_buf,
+					&dfu->b_left);
+			if (ret != 0) {
+				debug("%s: Read error!\n", __func__);
+				return ret;
+			}
+			dfu->offset += dfu->b_left;
+			dfu->r_left -= dfu->b_left;
+
+			puts("#");
+		}
+	}
+
+	return readn;
 }
 
 int dfu_read(struct dfu_entity *dfu, void *buf, int size, int blk_seq_num)
 {
-	static unsigned char *i_buf;
-	static int i_blk_seq_num;
-	static long r_size;
-	static u32 crc;
 	int ret = 0;
 
 	debug("%s: name: %s buf: 0x%p size: 0x%x p_num: 0x%x i_buf: 0x%p\n",
-	       __func__, dfu->name, buf, size, blk_seq_num, i_buf);
-
-	if (blk_seq_num == 0) {
-		i_buf = dfu_buf;
-		ret = dfu->read_medium(dfu, i_buf, &r_size);
-		debug("%s: %s %ld [B]\n", __func__, dfu->name, r_size);
-		i_blk_seq_num = 0;
-		/* Integrity check (if needed) */
-		crc = crc32(0, dfu_buf, r_size);
+	       __func__, dfu->name, buf, size, blk_seq_num, dfu->i_buf);
+
+	if (!dfu->inited) {
+		ret = dfu->read_medium(dfu, 0, NULL, &dfu->r_left);
+		if (ret != 0) {
+			debug("%s: failed to get r_left\n", __func__);
+			return ret;
+		}
+
+		debug("%s: %s %ld [B]\n", __func__, dfu->name, dfu->r_left);
+
+		dfu->i_blk_seq_num = 0;
+		dfu->crc = 0;
+		dfu->offset = 0;
+		dfu->i_buf_start = dfu_buf;
+		dfu->i_buf_end = dfu_buf + sizeof(dfu_buf);
+		dfu->i_buf = dfu->i_buf_start;
+		dfu->b_left = 0;
+
+		dfu->inited = 1;
 	}
 
-	if (i_blk_seq_num++ != blk_seq_num) {
+	if (dfu->i_blk_seq_num != blk_seq_num) {
 		printf("%s: Wrong sequence number! [%d] [%d]\n",
-		       __func__, i_blk_seq_num, blk_seq_num);
+		       __func__, dfu->i_blk_seq_num, blk_seq_num);
 		return -1;
 	}
+	/* handle rollover */
+	dfu->i_blk_seq_num = (dfu->i_blk_seq_num + 1) & 0xffff;
 
-	if (r_size >= size) {
-		memcpy(buf, i_buf, size);
-		i_buf += size;
-		r_size -= size;
-		return size;
-	} else {
-		memcpy(buf, i_buf, r_size);
-		i_buf += r_size;
-		debug("%s: %s CRC32: 0x%x\n", __func__, dfu->name, crc);
-		puts("UPLOAD ... done\nCtrl+C to exit ...\n");
+	ret = dfu_read_buffer_fill(dfu, buf, size);
+	if (ret < 0) {
+		printf("%s: Failed to fill buffer\n", __func__);
+		return -1;
+	}
+
+	if (ret < size) {
+		debug("%s: %s CRC32: 0x%x\n", __func__, dfu->name, dfu->crc);
+		puts("\nUPLOAD ... done\nCtrl+C to exit ...\n");
 
-		i_buf = NULL;
-		i_blk_seq_num = 0;
-		crc = 0;
-		return r_size;
+		dfu->i_blk_seq_num = 0;
+		dfu->crc = 0;
+		dfu->offset = 0;
+		dfu->i_buf_start = dfu_buf;
+		dfu->i_buf_end = dfu_buf + sizeof(dfu_buf);
+		dfu->i_buf = dfu->i_buf_start;
+		dfu->b_left = 0;
+
+		dfu->inited = 0;
 	}
+
 	return ret;
 }
 
diff --git a/drivers/dfu/dfu_mmc.c b/drivers/dfu/dfu_mmc.c
index 083d745..29a2c2e 100644
--- a/drivers/dfu/dfu_mmc.c
+++ b/drivers/dfu/dfu_mmc.c
@@ -22,6 +22,7 @@ 
 #include <common.h>
 #include <malloc.h>
 #include <errno.h>
+#include <div64.h>
 #include <dfu.h>
 
 enum dfu_mmc_op {
@@ -30,35 +31,48 @@  enum dfu_mmc_op {
 };
 
 static int mmc_block_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
-			void *buf, long *len)
+			u64 offset, void *buf, long *len)
 {
 	char cmd_buf[DFU_CMD_BUF_SIZE];
+	u32 blk_start, blk_count;
 
-	sprintf(cmd_buf, "mmc %s 0x%x %x %x",
-		op == DFU_OP_READ ? "read" : "write",
-		(unsigned int) buf,
-		dfu->data.mmc.lba_start,
-		dfu->data.mmc.lba_size);
-
-	if (op == DFU_OP_READ)
+	/* if buf == NULL return total size of the area */
+	if (buf == NULL) {
 		*len = dfu->data.mmc.lba_blk_size * dfu->data.mmc.lba_size;
+		return 0;
+	}
+
+	blk_start = dfu->data.mmc.lba_start +
+			(u32)lldiv(offset, dfu->data.mmc.lba_blk_size);
+	blk_count = *len / dfu->data.mmc.lba_blk_size;
+	if (blk_start + blk_count >
+			dfu->data.mmc.lba_start + dfu->data.mmc.lba_size) {
+		debug("%s: block_op out of bounds\n", __func__);
+		return -1;
+	}
+
+	sprintf(cmd_buf, "mmc %s %p %x %x",
+		op == DFU_OP_READ ? "read" : "write",
+		 buf, blk_start, blk_count);
 
 	debug("%s: %s 0x%p\n", __func__, cmd_buf, cmd_buf);
 	return run_command(cmd_buf, 0);
 }
 
-static inline int mmc_block_write(struct dfu_entity *dfu, void *buf, long *len)
+static inline int mmc_block_write(struct dfu_entity *dfu,
+		u64 offset, void *buf, long *len)
 {
-	return mmc_block_op(DFU_OP_WRITE, dfu, buf, len);
+	return mmc_block_op(DFU_OP_WRITE, dfu, offset, buf, len);
 }
 
-static inline int mmc_block_read(struct dfu_entity *dfu, void *buf, long *len)
+static inline int mmc_block_read(struct dfu_entity *dfu,
+		u64 offset, void *buf, long *len)
 {
-	return mmc_block_op(DFU_OP_READ, dfu, buf, len);
+	return mmc_block_op(DFU_OP_READ, dfu, offset, buf, len);
 }
 
 static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
-			void *buf, long *len)
+			u64 offset, void *buf, long *len)
 {
 	char cmd_buf[DFU_CMD_BUF_SIZE];
 	char *str_env;
@@ -66,12 +80,17 @@  static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
 
 	switch (dfu->layout) {
 	case DFU_FS_FAT:
-		sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx",
+		sprintf(cmd_buf, "fat%s mmc %d:%d 0x%x %s %lx %llx",
 			op == DFU_OP_READ ? "load" : "write",
 			dfu->data.mmc.dev, dfu->data.mmc.part,
-			(unsigned int) buf, dfu->name, *len);
+			(unsigned int) buf, dfu->name, *len, offset);
 		break;
 	case DFU_FS_EXT4:
+		if (offset != 0) {
+			debug("%s: Offset value %llx != 0 not supported!\n",
+					__func__, offset);
+			return -1;
+		}
 		sprintf(cmd_buf, "ext4%s mmc %d:%d /%s 0x%x %ld",
 			op == DFU_OP_READ ? "load" : "write",
 			dfu->data.mmc.dev, dfu->data.mmc.part,
@@ -80,6 +99,7 @@  static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
 	default:
 		printf("%s: Layout (%s) not (yet) supported!\n", __func__,
 		       dfu_get_layout(dfu->layout));
+		return -1;
 	}
 
 	debug("%s: %s 0x%p\n", __func__, cmd_buf, cmd_buf);
@@ -102,27 +122,30 @@  static int mmc_file_op(enum dfu_mmc_op op, struct dfu_entity *dfu,
 	return ret;
 }
 
-static inline int mmc_file_write(struct dfu_entity *dfu, void *buf, long *len)
+static inline int mmc_file_write(struct dfu_entity *dfu,
+		u64 offset, void *buf, long *len)
 {
-	return mmc_file_op(DFU_OP_WRITE, dfu, buf, len);
+	return mmc_file_op(DFU_OP_WRITE, dfu, offset, buf, len);
 }
 
-static inline int mmc_file_read(struct dfu_entity *dfu, void *buf, long *len)
+static inline int mmc_file_read(struct dfu_entity *dfu,
+		u64 offset, void *buf, long *len)
 {
-	return mmc_file_op(DFU_OP_READ, dfu, buf, len);
+	return mmc_file_op(DFU_OP_READ, dfu, offset, buf, len);
 }
 
-int dfu_write_medium_mmc(struct dfu_entity *dfu, void *buf, long *len)
+int dfu_write_medium_mmc(struct dfu_entity *dfu,
+		u64 offset, void *buf, long *len)
 {
 	int ret = -1;
 
 	switch (dfu->layout) {
 	case DFU_RAW_ADDR:
-		ret = mmc_block_write(dfu, buf, len);
+		ret = mmc_block_write(dfu, offset, buf, len);
 		break;
 	case DFU_FS_FAT:
 	case DFU_FS_EXT4:
-		ret = mmc_file_write(dfu, buf, len);
+		ret = mmc_file_write(dfu, offset, buf, len);
 		break;
 	default:
 		printf("%s: Layout (%s) not (yet) supported!\n", __func__,
@@ -132,17 +155,17 @@  int dfu_write_medium_mmc(struct dfu_entity *dfu, void *buf, long *len)
 	return ret;
 }
 
-int dfu_read_medium_mmc(struct dfu_entity *dfu, void *buf, long *len)
+int dfu_read_medium_mmc(struct dfu_entity *dfu, u64 offset, void *buf, long *len)
 {
 	int ret = -1;
 
 	switch (dfu->layout) {
 	case DFU_RAW_ADDR:
-		ret = mmc_block_read(dfu, buf, len);
+		ret = mmc_block_read(dfu, offset, buf, len);
 		break;
 	case DFU_FS_FAT:
 	case DFU_FS_EXT4:
-		ret = mmc_file_read(dfu, buf, len);
+		ret = mmc_file_read(dfu, offset, buf, len);
 		break;
 	default:
 		printf("%s: Layout (%s) not (yet) supported!\n", __func__,
@@ -181,13 +204,15 @@  int dfu_fill_entity_mmc(struct dfu_entity *dfu, char *s)
 
 		mmc = find_mmc_device(dev);
 		if (mmc == NULL || mmc_init(mmc)) {
-			printf("%s: could not find mmc device #%d!\n", __func__, dev);
+			printf("%s: could not find mmc device #%d!\n",
+					__func__, dev);
 			return -ENODEV;
 		}
 
 		blk_dev = &mmc->block_dev;
 		if (get_partition_info(blk_dev, part, &partinfo) != 0) {
-			printf("%s: could not find partition #%d on mmc device #%d!\n",
+			printf("%s: could not find partition #%d "
+					"on mmc device #%d!\n",
 					__func__, part, dev);
 			return -ENODEV;
 		}
@@ -209,5 +234,8 @@  int dfu_fill_entity_mmc(struct dfu_entity *dfu, char *s)
 	dfu->read_medium = dfu_read_medium_mmc;
 	dfu->write_medium = dfu_write_medium_mmc;
 
+	/* initial state */
+	dfu->inited = 0;
+
 	return 0;
 }
diff --git a/include/dfu.h b/include/dfu.h
index 5350d79..2847ef8 100644
--- a/include/dfu.h
+++ b/include/dfu.h
@@ -59,7 +59,7 @@  static inline unsigned int get_mmc_blk_size(int dev)
 
 #define DFU_NAME_SIZE 32
 #define DFU_CMD_BUF_SIZE 128
-#define DFU_DATA_BUF_SIZE (1024*1024*4) /* 4 MiB */
+#define DFU_DATA_BUF_SIZE (1024*64) /* 64 KB (the huge buffer is overkill) */
 
 struct dfu_entity {
 	char			name[DFU_NAME_SIZE];
@@ -73,10 +73,25 @@  struct dfu_entity {
 		struct mmc_internal_data mmc;
 	} data;
 
-	int (*read_medium)(struct dfu_entity *dfu, void *buf, long *len);
-	int (*write_medium)(struct dfu_entity *dfu, void *buf, long *len);
+	int (*read_medium)(struct dfu_entity *dfu,
+			u64 offset, void *buf, long *len);
+
+	int (*write_medium)(struct dfu_entity *dfu,
+			u64 offset, void *buf, long *len);
 
 	struct list_head list;
+
+	/* on the fly state */
+	u32 crc;
+	u64 offset;
+	int i_blk_seq_num;
+	u8 *i_buf;
+	u8 *i_buf_start;
+	u8 *i_buf_end;
+	long r_left;
+	long b_left;
+
+	unsigned int inited : 1;
 };
 
 int dfu_config_entities(char *s, char *interface, int num);