ieee802154: Add CA8210 IEEE 802.15.4 device driver

Add driver source and config for softMAC implementation of Cascoda's CA8210
IEEE 802.15.4 transceiver device. The driver mimics a common PHY-only
implementation despite the CA8210 being a hardMAC device which exposes a SAP
interface to the fully integrated MAC.

The chip is a modem-only device with an integrated processor which runs the
802.15.4 MAC. The chip communicates via full-duplex SPI with additional pins
for NIRQ and NRESET. The chip can also output its 16MHz clock to a GPIO with a
configurable divider.

The driver can be configured to implement a debugfs node that provides access
to the SAP-based API to drive mechanisms not currently supported by the
standard kernel interface.

Signed-off-by: Harry Morris <h.morris@cascoda.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

drivers/net/ieee802154/Kconfig

@@ -82,3 +82,25 @@ config IEEE802154_ADF7242
 
 	  This driver can also be built as a module. To do so, say M here.
 	  the module will be called 'adf7242'.
+
+config IEEE802154_CA8210
+	tristate "Cascoda CA8210 transceiver driver"
+	depends on IEEE802154_DRIVERS && MAC802154
+	depends on SPI
+	select COMMON_CLK
+	---help---
+	  Say Y here to enable the CA8210 SPI 802.15.4 wireless
+	  controller.
+
+	  This driver can also be built as a module. To do so, say M here.
+	  the module will be called 'ca8210'.
+
+config IEEE802154_CA8210_DEBUGFS
+	bool "CA8210 debugfs interface"
+	depends on IEEE802154_CA8210
+	depends on DEBUG_FS
+	---help---
+	  This option compiles debugfs code for the ca8210 driver. This
+	  exposes a debugfs node for each CA8210 instance which allows
+	  direct use of the Cascoda API, exposing the 802.15.4 MAC
+	  management entities.

drivers/net/ieee802154/Makefile

@@ -4,3 +4,4 @@ obj-$(CONFIG_IEEE802154_MRF24J40) += mrf24j40.o
 obj-$(CONFIG_IEEE802154_CC2520) += cc2520.o
 obj-$(CONFIG_IEEE802154_ATUSB) += atusb.o
 obj-$(CONFIG_IEEE802154_ADF7242) += adf7242.o
+obj-$(CONFIG_IEEE802154_CA8210) += ca8210.o