Add a return value to the event handler. Some I2C devices will
NAK if they have no data, so allow them to do this. This required
the following changes:
Go through all the event handlers and change them to return int
and return 0.
Modify i2c_start_transfer to terminate the transaction on a NAK.
Modify smbus handing to not assert if a NAK occurs on a second
operation, and terminate the transaction and return -1 instead.
Add some information on semantics to I2CSlaveClass.
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
d307c28ca9