net: dsa: add Arrow SpeedChips XRS700x driver

Add a driver with initial support for the Arrow SpeedChips XRS7000
series of gigabit Ethernet switch chips which are typically used in
critical networking applications.

The switches have up to three RGMII ports and one RMII port.
Management to the switches can be performed over i2c or mdio.

Support for advanced features such as PTP and
HSR/PRP (IEC 62439-3 Clause 5 & 4) is not included in this patch and
may be added at a later date.

Signed-off-by: George McCollister <george.mccollister@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/Kconfig

@@ -60,6 +60,8 @@ source "drivers/net/dsa/qca/Kconfig"
 
 source "drivers/net/dsa/sja1105/Kconfig"
 
+source "drivers/net/dsa/xrs700x/Kconfig"
+
 config NET_DSA_QCA8K
 	tristate "Qualcomm Atheros QCA8K Ethernet switch family support"
 	depends on NET_DSA

drivers/net/dsa/Makefile

@@ -24,3 +24,4 @@ obj-y				+= mv88e6xxx/
 obj-y				+= ocelot/
 obj-y				+= qca/
 obj-y				+= sja1105/
+obj-y				+= xrs700x/

drivers/net/dsa/xrs700x/Kconfig

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config NET_DSA_XRS700X
+	tristate
+	depends on NET_DSA
+	select NET_DSA_TAG_XRS700X
+	select REGMAP
+	help
+	  This enables support for Arrow SpeedChips XRS7003/7004 gigabit
+	  Ethernet switches.
+
+config NET_DSA_XRS700X_I2C
+	tristate "Arrow XRS7000X series switch in I2C mode"
+	depends on NET_DSA && I2C
+	select NET_DSA_XRS700X
+	select REGMAP_I2C
+	help
+	  Enable I2C support for Arrow SpeedChips XRS7003/7004 gigabit Ethernet
+	  switches.
+
+config NET_DSA_XRS700X_MDIO
+	tristate "Arrow XRS7000X series switch in MDIO mode"
+	depends on NET_DSA
+	select NET_DSA_XRS700X
+	help
+	  Enable MDIO support for Arrow SpeedChips XRS7003/7004 gigabit Ethernet
+	  switches.

drivers/net/dsa/xrs700x/Makefile

@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_NET_DSA_XRS700X) += xrs700x.o
+obj-$(CONFIG_NET_DSA_XRS700X_I2C) += xrs700x_i2c.o
+obj-$(CONFIG_NET_DSA_XRS700X_MDIO) += xrs700x_mdio.o