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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/pc87427
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 pc87427
+=====================
+
+Supported chips:
+ * National Semiconductor PC87427
+ Prefix: 'pc87427'
+ Addresses scanned: none, address read from Super I/O config space
+ Datasheet: No longer available
+
+Author: Jean Delvare <jdelvare@suse.de>
+
+Thanks to Amir Habibi at Candelis for setting up a test system, and to
+Michael Kress for testing several iterations of this driver.
+
+
+Description
+-----------
+
+The National Semiconductor Super I/O chip includes complete hardware
+monitoring capabilities. It can monitor up to 18 voltages, 8 fans and
+6 temperature sensors. Only the fans and temperatures are supported at
+the moment, voltages aren't.
+
+This chip also has fan controlling features (up to 4 PWM outputs),
+which are partly supported by this driver.
+
+The driver assumes that no more than one chip is present, which seems
+reasonable.
+
+
+Fan Monitoring
+--------------
+
+Fan rotation speeds are reported as 14-bit values from a gated clock
+signal. Speeds down to 83 RPM can be measured.
+
+An alarm is triggered if the rotation speed drops below a programmable
+limit. Another alarm is triggered if the speed is too low to be measured
+(including stalled or missing fan).
+
+
+Fan Speed Control
+-----------------
+
+Fan speed can be controlled by PWM outputs. There are 4 possible modes:
+always off, always on, manual and automatic. The latter isn't supported
+by the driver: you can only return to that mode if it was the original
+setting, and the configuration interface is missing.
+
+
+Temperature Monitoring
+----------------------
+
+The PC87427 relies on external sensors (following the SensorPath
+standard), so the resolution and range depend on the type of sensor
+connected. The integer part can be 8-bit or 9-bit, and can be signed or
+not. I couldn't find a way to figure out the external sensor data
+temperature format, so user-space adjustment (typically by a factor 2)
+may be required.