hwmon: Add support for INA3221 Triple Current/Voltage Monitors

Add support for the the INA3221 26v capable, Triple channel,
Bi-Directional, Zero-Drift, Low-/High-Side, Current/Voltage Monitor
with I2C interface.
Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/ina3221

+Kernel driver ina3221
+=====================
+
+Supported chips:
+  * Texas Instruments INA3221
+    Prefix: 'ina3221'
+    Addresses: I2C 0x40 - 0x43
+    Datasheet: Publicly available at the Texas Instruments website
+               http://www.ti.com/
+
+Author: Andrew F. Davis <afd@ti.com>
+
+Description
+-----------
+
+The Texas Instruments INA3221 monitors voltage, current, and power on the high
+side of up to three D.C. power supplies. The INA3221 monitors both shunt drop
+and supply voltage, with programmable conversion times and averaging, current
+and power are calculated host-side from these.
+
+Sysfs entries
+-------------
+
+in[123]_input           Bus voltage(mV) channels
+curr[123]_input         Current(mA) measurement channels
+shunt[123]_resistor     Shunt resistance(uOhm) channels
+curr[123]_crit          Critical alert current(mA) setting, activates the
+                          corresponding alarm when the respective current
+                          is above this value
+curr[123]_crit_alarm    Critical alert current limit exceeded
+curr[123]_max           Warning alert current(mA) setting, activates the
+                          corresponding alarm when the respective current
+                          average is above this value.
+curr[123]_max_alarm     Warning alert current limit exceeded
+in[456]_input           Shunt voltage(uV) for channels 1, 2, and 3 respectively

drivers/hwmon/Kconfig

@@ -1525,6 +1525,17 @@ config SENSORS_INA2XX
 	  This driver can also be built as a module.  If so, the module
 	  will be called ina2xx.
 
+config SENSORS_INA3221
+	tristate "Texas Instruments INA3221 Triple Power Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for  the TI INA3221 Triple Power
+	  Monitor.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ina3221.
+
 config SENSORS_TC74
 	tristate "Microchip TC74"
 	depends on I2C

drivers/hwmon/Makefile

@@ -77,6 +77,7 @@ obj-$(CONFIG_SENSORS_IBMPOWERNV)+= ibmpowernv.o
 obj-$(CONFIG_SENSORS_IIO_HWMON) += iio_hwmon.o
 obj-$(CONFIG_SENSORS_INA209)	+= ina209.o
 obj-$(CONFIG_SENSORS_INA2XX)	+= ina2xx.o
+obj-$(CONFIG_SENSORS_INA3221)	+= ina3221.o
 obj-$(CONFIG_SENSORS_IT87)	+= it87.o
 obj-$(CONFIG_SENSORS_JC42)	+= jc42.o
 obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o