ratp: add more build dependencies ...

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

crc: import crc_itu_t() from kernel ...

Our cyc_crc16() function is the same function as crc_itu_t() in the
Linux kernel. Import and use crc_itu_t() from the Kernel for
consistency.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Merge branch 'for-next/ratp'

ratp: select CMDLINE_EDITING ...

ratp seems to send special characters which are not handle correctly
without CDMLINE_EDITING. Without this config, commands run via ratp will
have an erratic behavior and/or incorrect output.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ratp: implement support for GPIO commands ...

Introduce three new RATP commands that allow getting and setting GPIO
values as well as configuring the direction of the GPIO pins.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ratp: implement i2c read/write support ...

Introduce two new RATP commands that allow running i2c read/write
operations, very similar in format to the already existing md/mw
RATP commands.

The messages are defined with a fixed 16-bit long register field, but
it will only be treated as a 16-bit address if I2C_FLAG_WIDE_ADDRESS
is set in the message flags field. If this flag is unset, the start
register address is assumed 8-bit long.

If the message includes the I2C_FLAG_MASTER_MODE flag, the start
register field is ignored and a i2c master send/receive operation is
performed.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ratp: moved logic to its own subdirectory ...

We are going to add new RATP command implementations in separate files
within this subdirectory.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>