Hi Daniel,

The i2c bus requires 5 bytes to do a 1 byte read (1-byte i2c address + 2
byte offset + 1-byte i2c address + 1 byte data), or 4 bytes to do a
1-byte write (1 byte i2c address + 2 byte offset + 1 byte data).

By taking a length with reads and writes, the driver can amortize
transaction overhead by performing larger transactions where appropriate.

This patch just sets up the new API.  Later patches refactor reads/writes
to take advantage of the larger transactions.

These functions are also now return any errors reported by the i2c layer.

Signed-off-by: Daniel Kurtz <redacted>
---

In the cyttsp a dedicate tx buffer is used, which is a bit easier on
the eyes. OTOH, the write operation seems infrequent enough to not
matter much, so

    Acked-by: Henrik Rydberg [off-list ref]

Thanks for your patience,
Henrik