hwmon: Add driver for ADT7411 voltage and temperature sensor

Add basic support for the ADT7411. Reads out all conversion results (via I2C,
SPI yet missing) and allows some on-the-fly configuration. Tested with a
custom board.
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

Documentation/hwmon/adt7411

+Kernel driver adt7411
+=====================
+
+Supported chips:
+  * Analog Devices ADT7411
+    Prefix: 'adt7411'
+    Addresses scanned: 0x48, 0x4a, 0x4b
+    Datasheet: Publicly available at the Analog Devices website
+
+Author: Wolfram Sang (based on adt7470 by Darrick J. Wong)
+
+Description
+-----------
+
+This driver implements support for the Analog Devices ADT7411 chip. There may
+be other chips that implement this interface.
+
+The ADT7411 can use an I2C/SMBus compatible 2-wire interface or an
+SPI-compatible 4-wire interface. It provides a 10-bit analog to digital
+converter which measures 1 temperature, vdd and 8 input voltages. It has an
+internal temperature sensor, but an external one can also be connected (one
+loses 2 inputs then). There are high- and low-limit registers for all inputs.
+
+Check the datasheet for details.
+
+sysfs-Interface
+---------------
+
+in0_input	- vdd voltage input
+in[1-8]_input	- analog 1-8 input
+temp1_input	- temperature input
+
+Besides standard interfaces, this driver adds (0 = off, 1 = on):
+
+  adc_ref_vdd	- Use vdd as reference instead of 2.25 V
+  fast_sampling	- Sample at 22.5 kHz instead of 1.4 kHz, but drop filters
+  no_average	- Turn off averaging over 16 samples
+
+Notes
+-----
+
+SPI, external temperature sensor and limit registers are not supported yet.

drivers/hwmon/Kconfig

@@ -170,6 +170,16 @@ config SENSORS_ADM9240
 	  This driver can also be built as a module.  If so, the module
 	  will be called adm9240.
 
+config SENSORS_ADT7411
+	tristate "Analog Devices ADT7411"
+	depends on I2C && EXPERIMENTAL
+	help
+	  If you say yes here you get support for the Analog Devices
+	  ADT7411 voltage and temperature monitoring chip.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called adt7411.
+
 config SENSORS_ADT7462
 	tristate "Analog Devices ADT7462"
 	depends on I2C && EXPERIMENTAL

drivers/hwmon/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_SENSORS_ADM1029)	+= adm1029.o
 obj-$(CONFIG_SENSORS_ADM1031)	+= adm1031.o
 obj-$(CONFIG_SENSORS_ADM9240)	+= adm9240.o
 obj-$(CONFIG_SENSORS_ADS7828)	+= ads7828.o
+obj-$(CONFIG_SENSORS_ADT7411)	+= adt7411.o
 obj-$(CONFIG_SENSORS_ADT7462)	+= adt7462.o
 obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
 obj-$(CONFIG_SENSORS_ADT7473)	+= adt7473.o