> +	/* FIXME: only single write request supported to 7-bit addr */

Hmm, this is quite limited. Would it be very hard to support multiple
messages? Or reads? 10 bits don't matter.

> +	if (!dev->pdata->has_alt_cmd)
> +		return -EOPNOTSUPP;

We should handle this in probe(), I think:

	if (dev->pdata->has_alt_cmd)
		at91_twi_algorithm.master_xfer_atomic = at91_twi_xfer_atomic;