Print a debug() message with the I2C speed is exceeded.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

Add a convenience function to access the private data that a uclass stores
for each of its devices. Convert over most existing uses for consistency
and to provide an example for others.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present we go through various contortions to store the I2C's chip
address in its private data. This only exists when the chip is active so
must be set up when it is probed. Until the device is probed we don't
actually record what address it will appear on.

However, now that we can support per-child platform data, we can use that
instead. This allows us to set up the address when the child is bound,
and avoid the messy contortions.

Unfortunately this is a fairly large change and it seems to be difficult to
break it down further.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>

Rather than assuming that the chip offset length is 1, allow it to be
provided. This allows chips that don't use the default offset length to
be used (at present they are only supported by the command line 'i2c'
command which sets the offset length explicitly).

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>

This driver includes some test features such as only supporting certain
bus speeds. It passes its I2C traffic through to an emulator.

Acked-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Masahiro Yamada <yamada.m@jp.panasonic.com>