hwmon: Driver for ADT7410

This patch brings basic support for the Analog Devices ADT7410 temperature
sensor. The following functionality has been implemented:

  * get current temperature
  * get/set minimum, maximum and critical temperature
  * get/set hysteresis
  * get alarm events for minimum, maximum and critical temperature

All implemented sysfs attributes have been sucessfully tested at temperatures
of 15°C to 40°C.

Signed-off-by: Hartmut Knaack <knaack.h@gmx.de>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/adt7410

@@ -0,0 +1,51 @@
+Kernel driver adt7410
+=====================
+
+Supported chips:
+  * Analog Devices ADT7410
+    Prefix: 'adt7410'
+    Addresses scanned: I2C 0x48 - 0x4B
+    Datasheet: Publicly available at the Analog Devices website
+               http://www.analog.com/static/imported-files/data_sheets/ADT7410.pdf
+
+Author: Hartmut Knaack <knaack.h@gmx.de>
+
+Description
+-----------
+
+The ADT7410 is a temperature sensor with rated temperature range of -55°C to
++150°C. It has a high accuracy of +/-0.5°C and can be operated at a resolution
+of 13 bits (0.0625°C) or 16 bits (0.0078°C). The sensor provides an INT pin to
+indicate that a minimum or maximum temperature set point has been exceeded, as
+well as a critical temperature (CT) pin to indicate that the critical
+temperature set point has been exceeded. Both pins can be set up with a common
+hysteresis of 0°C - 15°C and a fault queue, ranging from 1 to 4 events. Both
+pins can individually set to be active-low or active-high, while the whole
+device can either run in comparator mode or interrupt mode. The ADT7410
+supports continous temperature sampling, as well as sampling one temperature
+value per second or even justget one sample on demand for power saving.
+Besides, it can completely power down its ADC, if power management is
+required.
+
+Configuration Notes
+-------------------
+
+Since the device uses one hysteresis value, which is an offset to minimum,
+maximum and critical temperature, it can only be set for temp#_max_hyst.
+However, temp#_min_hyst and temp#_crit_hyst show their corresponding
+hysteresis.
+The device is set to 16 bit resolution and comparator mode.
+
+sysfs-Interface
+---------------
+
+temp#_input		- temperature input
+temp#_min		- temperature minimum setpoint
+temp#_max		- temperature maximum setpoint
+temp#_crit		- critical temperature setpoint
+temp#_min_hyst		- hysteresis for temperature minimum (read-only)
+temp#_max_hyst		- hysteresis for temperature maximum (read/write)
+temp#_crit_hyst		- hysteresis for critical temperature (read-only)
+temp#_min_alarm		- temperature minimum alarm flag
+temp#_max_alarm		- temperature maximum alarm flag
+temp#_crit_alarm	- critical temperature alarm flag