hwmon: add Texas Instruments TPS23861 driver

Add basic monitoring support as well as port on/off control for Texas
Instruments TPS23861 PoE PSE IC.
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Cc: Luka Perkov <luka.perkov@sartura.hr>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210121134434.2782405-2-robert.marko@sartura.hrSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/index.rst

@@ -177,6 +177,7 @@ Hardware Monitoring Kernel Drivers
    tmp401
    tmp421
    tmp513
+   tps23861
    tps40422
    tps53679
    twl4030-madc-hwmon

Documentation/hwmon/tps23861.rst

+.. SPDX-License-Identifier: GPL-2.0-only
+
+Kernel driver tps23861
+======================
+
+Supported chips:
+  * Texas Instruments TPS23861
+
+    Prefix: 'tps23861'
+
+    Datasheet: https://www.ti.com/lit/gpn/tps23861
+
+Author: Robert Marko <robert.marko@sartura.hr>
+
+Description
+-----------
+
+This driver supports hardware monitoring for Texas Instruments TPS23861 PoE PSE.
+
+TPS23861 is a quad port IEEE802.3at PSE controller with optional I2C control
+and monitoring capabilities.
+
+TPS23861 offers three modes of operation: Auto, Semi-Auto and Manual.
+
+This driver only supports the Auto mode of operation providing monitoring
+as well as enabling/disabling the four ports.
+
+Sysfs entries
+-------------
+
+======================= =====================================================================
+in[0-3]_input		Voltage on ports [1-4]
+in[0-3]_label		"Port[1-4]"
+in4_input		IC input voltage
+in4_label		"Input"
+temp1_input		IC die temperature
+temp1_label		"Die"
+curr[1-4]_input		Current on ports [1-4]
+in[1-4]_label		"Port[1-4]"
+in[0-3]_enable		Enable/disable ports [1-4]
+======================= =====================================================================

drivers/hwmon/Kconfig

@@ -1133,6 +1133,17 @@ config SENSORS_TC654
 	  This driver can also be built as a module. If so, the module
 	  will be called tc654.
 
+config SENSORS_TPS23861
+	tristate "Texas Instruments TPS23861 PoE PSE"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for Texas Instruments
+	  TPS23861 802.3at PoE PSE chips.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called tps23861.
+
 config SENSORS_MENF21BMC_HWMON
 	tristate "MEN 14F021P00 BMC Hardware Monitoring"
 	depends on MFD_MENF21BMC

drivers/hwmon/Makefile

@@ -144,6 +144,7 @@ obj-$(CONFIG_SENSORS_MAX31790)	+= max31790.o
 obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
 obj-$(CONFIG_SENSORS_MCP3021)	+= mcp3021.o
 obj-$(CONFIG_SENSORS_TC654)	+= tc654.o
+obj-$(CONFIG_SENSORS_TPS23861)	+= tps23861.o
 obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
 obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
 obj-$(CONFIG_SENSORS_MR75203)	+= mr75203.o