net: lora: Add Semtech SX1301

The Semtech SX1301 was the first multi-channel LoRa "concentrator".
It uses a SPI interface to the host as well as a dual SPI interface to
its radios. These two have been implemented as spi_controller, so that
the Device Tree can specify whether the respective module uses two
SX1257, two SX1255 or a combination of these or some unforeseen chipset.

This implementation is the most recent - initialization is not yet
complete, it will need to load firmware into the two on-chip MCUs.

Unfortunately there is no full datasheet with register descriptions,
only a BSD-licensed userspace HAL implementation using spidev devices.
Therefore some register names are unknown.

Cc: Ben Whitten <ben.whitten@lairdtech.com>
Cc: Steve deRosier <derosier@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Michael Röder <michael.roeder@avnet.eu>
Cc: Ken Yu (禹凯) <ken.yu@rakwireless.com>
Cc: linux-spi@vger.kernel.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
3 files changed