hwmon: Add support for Lattice's POWR1220 power manager IC

This patch adds support for Lattice's POWR1220 power manager IC. Read
access to all the ADCs on the chip are supported through the hwmon
sysfs files.
Signed-off-by: Scott Kanowitz <skanowitz@echo360.com>
[Guenter Roeck: Removed some extra ( )]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/powr1220

+Kernel driver powr1220
+==================
+
+Supported chips:
+  * Lattice POWR1220AT8
+    Prefix: 'powr1220'
+    Addresses scanned: none
+    Datasheet: Publicly available at the Lattice website
+               http://www.latticesemi.com/
+
+Author: Scott Kanowitz <scott.kanowitz@gmail.com>
+
+Description
+-----------
+
+This driver supports the Lattice POWR1220AT8 chip. The POWR1220
+includes voltage monitoring for 14 inputs as well as trim settings
+for output voltages and GPIOs. This driver implements the voltage
+monitoring portion of the chip.
+
+Voltages are sampled by a 12-bit ADC with a step size of 2 mV.
+An in-line attenuator allows measurements from 0 to 6 V. The
+attenuator is enabled or disabled depending on the setting of the
+input's max value. The driver will enable the attenuator for any
+value over the low measurement range maximum of 2 V.
+
+The input naming convention is as follows:
+
+driver name    pin name
+in0            VMON1
+in1            VMON2
+in2            VMON3
+in2            VMON4
+in4            VMON5
+in5            VMON6
+in6            VMON7
+in7            VMON8
+in8            VMON9
+in9            VMON10
+in10           VMON11
+in11           VMON12
+in12           VCCA
+in13           VCCINP
+
+The ADC readings are updated on request with a minimum period of 1s.

drivers/hwmon/Kconfig

@@ -608,6 +608,18 @@ config SENSORS_JC42
 	  This driver can also be built as a module.  If so, the module
 	  will be called jc42.
 
+config SENSORS_POWR1220
+	tristate "Lattice POWR1220 Power Monitoring"
+	depends on I2C
+	default n
+	help
+	  If you say yes here you get access to the hardware monitoring
+	  functions of the Lattice POWR1220 isp Power Supply Monitoring,
+	  Sequencing and Margining Controller.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called powr1220.
+
 config SENSORS_LINEAGE
 	tristate "Lineage Compact Power Line Power Entry Module"
 	depends on I2C

drivers/hwmon/Makefile

@@ -120,6 +120,7 @@ obj-$(CONFIG_SENSORS_NTC_THERMISTOR)	+= ntc_thermistor.o
 obj-$(CONFIG_SENSORS_PC87360)	+= pc87360.o
 obj-$(CONFIG_SENSORS_PC87427)	+= pc87427.o
 obj-$(CONFIG_SENSORS_PCF8591)	+= pcf8591.o
+obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o