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authorYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 12:17:53 -0700
committerYunhong Jiang <yunhong.jiang@intel.com>2015-08-04 15:44:42 -0700
commit9ca8dbcc65cfc63d6f5ef3312a33184e1d726e00 (patch)
tree1c9cafbcd35f783a87880a10f85d1a060db1a563 /kernel/Documentation/hwmon/lm80
parent98260f3884f4a202f9ca5eabed40b1354c489b29 (diff)
Add the rt linux 4.1.3-rt3 as base
Import the rt linux 4.1.3-rt3 as OPNFV kvm base. It's from git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git linux-4.1.y-rt and the base is: commit 0917f823c59692d751951bf5ea699a2d1e2f26a2 Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Date: Sat Jul 25 12:13:34 2015 +0200 Prepare v4.1.3-rt3 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> We lose all the git history this way and it's not good. We should apply another opnfv project repo in future. Change-Id: I87543d81c9df70d99c5001fbdf646b202c19f423 Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
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+Kernel driver lm80
+==================
+
+Supported chips:
+ * National Semiconductor LM80
+ Prefix: 'lm80'
+ Addresses scanned: I2C 0x28 - 0x2f
+ Datasheet: Publicly available at the National Semiconductor website
+ http://www.national.com/
+ * National Semiconductor LM96080
+ Prefix: 'lm96080'
+ Addresses scanned: I2C 0x28 - 0x2f
+ Datasheet: Publicly available at the National Semiconductor website
+ http://www.national.com/
+
+Authors:
+ Frodo Looijaard <frodol@dds.nl>,
+ Philip Edelbrock <phil@netroedge.com>
+
+Description
+-----------
+
+This driver implements support for the National Semiconductor LM80.
+It is described as a 'Serial Interface ACPI-Compatible Microprocessor
+System Hardware Monitor'. The LM96080 is a more recent incarnation,
+it is pin and register compatible, with a few additional features not
+yet supported by the driver.
+
+The LM80 implements one temperature sensor, two fan rotation speed sensors,
+seven voltage sensors, alarms, and some miscellaneous stuff.
+
+Temperatures are measured in degrees Celsius. There are two sets of limits
+which operate independently. When the HOT Temperature Limit is crossed,
+this will cause an alarm that will be reasserted until the temperature
+drops below the HOT Hysteresis. The Overtemperature Shutdown (OS) limits
+should work in the same way (but this must be checked; the datasheet
+is unclear about this). Measurements are guaranteed between -55 and
++125 degrees. The current temperature measurement has a resolution of
+0.0625 degrees; the limits have a resolution of 1 degree.
+
+Fan rotation speeds are reported in RPM (rotations per minute). An alarm is
+triggered if the rotation speed has dropped below a programmable limit. Fan
+readings can be divided by a programmable divider (1, 2, 4 or 8) to give
+the readings more range or accuracy. Not all RPM values can accurately be
+represented, so some rounding is done. With a divider of 2, the lowest
+representable value is around 2600 RPM.
+
+Voltage sensors (also known as IN sensors) report their values in volts.
+An alarm is triggered if the voltage has crossed a programmable minimum
+or maximum limit. Note that minimum in this case always means 'closest to
+zero'; this is important for negative voltage measurements. All voltage
+inputs can measure voltages between 0 and 2.55 volts, with a resolution
+of 0.01 volt.
+
+If an alarm triggers, it will remain triggered until the hardware register
+is read at least once. This means that the cause for the alarm may
+already have disappeared! Note that in the current implementation, all
+hardware registers are read whenever any data is read (unless it is less
+than 2.0 seconds since the last update). This means that you can easily
+miss once-only alarms.
+
+The LM80 only updates its values each 1.5 seconds; reading it more often
+will do no harm, but will return 'old' values.