net: pse-pd: Add Si3474 PSE controller driver

Add a driver for the Skyworks Si3474 I2C Power Sourcing Equipment
controller.

Driver supports basic features of Si3474 IC:
- get port status,
- get port power,
- get port voltage,
- enable/disable port power.

Only 4p configurations are supported at this moment.

Signed-off-by: Piotr Kubik <piotr.kubik@adtran.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/9b72c8cd-c8d3-4053-9c80-671b9481d166@adtran.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/pse-pd/Kconfig

@@ -32,6 +32,17 @@ config PSE_PD692X0
 	  To compile this driver as a module, choose M here: the
 	  module will be called pd692x0.
 
+config PSE_SI3474
+	tristate "Si3474 PSE controller"
+	depends on I2C
+	help
+	  This module provides support for Si3474 regulator based Ethernet
+	  Power Sourcing Equipment.
+	  Only 4-pair PSE configurations are supported.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called si3474.
+
 config PSE_TPS23881
 	tristate "TPS23881 PSE controller"
 	depends on I2C

drivers/net/pse-pd/Makefile

@@ -5,4 +5,5 @@ obj-$(CONFIG_PSE_CONTROLLER) += pse_core.o
 
 obj-$(CONFIG_PSE_REGULATOR) += pse_regulator.o
 obj-$(CONFIG_PSE_PD692X0) += pd692x0.o
+obj-$(CONFIG_PSE_SI3474) += si3474.o
 obj-$(CONFIG_PSE_TPS23881) += tps23881.o